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Hybrid rice needs to prevent lodging due to excessive grain weight during maturity, which can lead to yield loss, grain quality deterioration and difficulty in harvesting. Breeding excellent parents (restorer and male-sterile lines) is the foundation for cultivating lodging-resistant hybrid rice. However, there is still limited information about restorers with improved lodging resistance. To identify a new restorer with significantly enhanced resistance to lodging, the restorer line Huazhan, which has been used for many years in hybrid rice breeding in China, was used as the control, to evaluate the lodging resistance of the new restorer R382. A two-year field experiment was executed to investigate the difference on lodging-related traits of the basal two internodes above-ground, such as out diameters of stems with or without leaf sheath (DWS, DWOS), culm thickness (CT), the section modulus (SM), bending stress (BS), and bending moment at break (M). The results indicated that DWS, CT, BS, M of R382 was at least 19.9%, 13.3%, 36.5% and 52.6% higher than that of Huazhan. However, the negative indicator lodging index of R382 was over 17.5% lower. The number and area of vascular bundles, and the contents of the chemical components of the cell wall including cellulose, lignin, and hemicellulose, together with the accumulation of starch granules, were significantly greater in R382. Furthermore, in the basal stems during the jointing stage, a series of genes that promote cell wall formation exhibited significantly higher expression levels in R382. Meanwhile, there was no significant difference in the yield of R382 and Huazhan. Thus, this new restorer could be a valuable donor in the future hybrid rice breeding programs for improving lodging resistance. [ABSTRACT FROM AUTHOR]

With the continuous development of underground engineering to the deep, complex geologic conditions such as high stress, extremely soft rock and fault fracture zone usually occurred in the construction process. The accurate calculation of confined concrete arch bearing capacity is the key to support design. At present, the theoretical value of the bearing capacity for the confined concrete arch is oppositely deduced according to the axial compression bearing capacity of basic component, and the bending moment effect of surrounding rock on arch is neglected. It does not consider the structural characteristics of inconsistent stiffness between the arch joints and segments. To obtain accurate calculation results, a theoretical calculation model of arch with arbitrary section numbers and unequal stiffness is established. By the full-scale laboratory and numerical tests, the deformation and failure characteristics of the confined concrete arch are analyzed. The results show that the vault position, bottom position and waist position are the key failure positions of the arch. The difference rates of theoretical calculation results compared with laboratory test results of ultimate bearing capacity are within 5%, which verifies the rationality and correctness of theoretical calculation model. On the basis of the above research, the support design method of confined concrete arch is proposed. The support parameters of on-site confined concrete arch are designed based on the engineering background of the typical deep mine with high stress—Liangjia coal mine located in China. The surrounding rock of the roadway is stably controlled. [ABSTRACT FROM AUTHOR]

Precision hill-drop direct seeding using mechanical drilling is a unique direct seeding technique employed in south China that offers advantages such as excellent grain yield and high lodging resistance. Improving yield and lodging-related traits is essential for efforts to improve mechanically direct-seeded rice (MDSR) production. Seeding rates (SR) and nitrogen (N) fertilization rate are two of the main factors affecting grain yield and lodging resistance under MDSR production. However, little information about double-season MDSR production in south China is available. Here, we evaluated yield and lodging risk for two rice cultivars Huanghuazhan, HHZ, lodging-resistant; Xiangyaxiangzhan, XYXZ, lodging-susceptible across two consecutive growing seasons under two under two seeding rates (LSR, 30 cm × 18 cm; HSR, 30 cm × 12 cm) and three N fertilization rates (N1 = 100 kg ha−1, reduced N; N2 = 150 kg ha−1, normal N; and N3 = 200 kg ha−1, enhanced N). We found that increased SR and N fertilization rate improved grain yield and increased lodging risk. SR and N were consistently and positively related to plant height (PH), gravity center height (GCH), the length from the broken basal internode to the panicle tip (SL), the fresh plant weight of the plant part above the broken point (FW), and the length of the two basal internodes. SR and N decreased breaking force (F) and breaking strength (BM), driving increased lodging risk as reflected by increases in lodging index (LI) values. Culm diameter (CD) and culm wall thickness (CWT) did not respond consistently to SR and N treatments. Correlation analysis revealed that PH, GCH, the length of first and second basal internodes, FW, and bending moment for the whole plant (WP) were positively correlated with LI, while F and BM were negatively associated with LI. These findings suggest that the increased lodging risk resulting from high SR could be mitigated by applying appropriate rates of N; that is, this work suggests that grain yield can be maximized and lodging risk minimized by increasing SR while decreasing N fertilization rate. Seasonal differences in the effects of SR and N fertilization should be considered to achieve a high grain yield and maintain high lodging resistance. Our study suggests that increasing SR and decreasing N fertilization can enhance rice grain yield while improving lodging resistance for both varieties. Optimizing grain yield by increasing SR while reducing lodging risk by lowering N application rates may maintain lodging resistance and improve grain yield. [ABSTRACT FROM AUTHOR]

During pipeline construction and operation, the occurrence of surface dents presents a critical concern, primarily arising from factors such as pipeline installation and geological forces exerted upon the pipeline, particularly in the form of rock protrusion. These dents pose a significant threat to the pipeline's safe functionality and have the potential to diminish its load-bearing capacity. Presently, China's oil and gas pipelines predominantly employ X80 high-grade steel. It is noteworthy that prior research into the ultimate load capacity of dented pipelines has largely centered on medium and low-grade steels. The implications of these findings for the suitability of the X80 pipeline remain inconclusive. Consequently, it is imperative to undertake a comprehensive investigation into the load-bearing capacity of high-grade steel pipelines with dent defects. In addition to internal pressure, variations in the pipeline's transported medium, ambient temperature fluctuations, soil displacement, and other factors introduce additional loading effects, including bending moments and axial loads. These supplementary loads introduce latent hazards to the pipeline's operational safety. Hence, this research endeavors to investigate the ultimate load-bearing capacity of X80-grade dented pipelines under the influence of typical loading conditions and to identify pertinent factors that affect this capacity. Finite element analysis (FEA) is deployed to study the behavior of the dented pipelines under typical loads. Failure criterion for ascertaining the ultimate load is proposed and verified by the comparison to test results. Furthermore, the impact of varying dent sizes on the ultimate load capacity of X80-grade dented pipelines is examined. These findings serve as a robust foundation for the safety assessment of dented pipelines, ensuring the sustained safe operation of these vital infrastructures. [ABSTRACT FROM AUTHOR]

Hard roof's 3D breaking characteristics is vital for mining pressure control. However, the research concerning a longwall face that employs an innovative roof-cutting technology via a chainsaw arm machine (RCTCAM) is scant. To address this gap, this paper thoroughly analyzes RCTCAM's core equipment and roof-cutting procedures. Firstly, the thin elastic plate theory and the superposition principle were applied to establish the first and periodic break mechanical models of hard roofs using the RCTCAM. These mechanical models elucidated the distribution laws of the first and third principal bending moments in a hard roof. Following this, based on tensile failure criteria and crack expansion criteria, the study uncovered that the hard roof's first break transitioned from an 'O–X' shape to a 'U–Y' shape, while its periodic break morphed from a 'C–ン' shape to an 'L–ノ' shape. This transformation led to a unique phenomenon. The rotation of arc-shaped triangular plates formed during the 'O–X' and 'C–ン' -shaped breaks resulted in severe damage to a gob-side roadway. However, a longwall face employing the RCTCAM did not produce such plates, effectively avoiding the associated damage. By implementing the RCTCAM in Workface 8311 of the Yanya Mine in China, the stress peaks of the coal pillars were reduced on average by 22.8%, and the deformation of the roadway decreased by 27.8%. These findings underline the success of the RCTCAM in achieving pressure relief for a gob-side roadway. Highlights: It was given that the theoretical calculation method for deflection, bending moment, and stress of a hard roof with the RCTCAM under the first and periodic breaks. When with the RCTCAM, hard roof's first break exhibits a transition from an 'O-X' shape to an 'U-Y' shape, while its periodic break changes from a 'C-ン' shape to an 'L-ノ' shape. Due to rotation of arc-shaped triangular plates formed in the 'O-X' and 'C-ン'-shaped breaks, a gob-side roadway bear severe damage. However, a longwall face with the RCTCAM has no such plates, thus avoiding damage. With the RCTCAM in Workface 8311 of the Yanya Mine, China, the stress peaks of a gob-side roadway's coal pillars dropped averagely by 22.8%, indicating that the RCTCAM achieve pressure relief for a gob-side roadway. [ABSTRACT FROM AUTHOR]

There are many problems in the development of urban space in China. Among them, urban tunnels generally pass through many sections with very complicated geological conditions, and the construction will encounter great difficulties, so the mechanical behavior of shield segments in different complex strata is worth discussing. In this paper, the axial force, bending moment and pore water pressure of shield tunnel segments in the soft and hard uneven stratum, clay stratum and fully weathered granite stratum of overlying buildings are studied by establishing a rectangular element mechanical model based on the field test method. The analysis shows that the mechanical properties of shield tunnels in different strata are quite different, but their mechanical properties change stages are the same. The earth pressure on the left and right sides of the test ring is asymmetric in the soft and hard uneven stratum, and the vault pressure is much greater than the vault bottom pressure. The distribution of earth pressure in each position of the segment ring in clay stratum is relatively balanced, and the earth pressure on both sides is relatively small; in the fully weathered granite layer of the overlying building, the segment ring of the test ring is subjected to greater additional stress, and the internal force of the segment is much greater than that without the overlying building. Exploring the similarities and differences of segment stress in these three complex strata can provide an important basis for the design and construction of shield segments in complex strata. [ABSTRACT FROM AUTHOR]

A water delivery system can be gradually away from the normal state of the canal operation in northern China in winter. Water diversion projects can be launched to meet the harsh requirement on the large and medium-sized city's residents living water and industrial water consumption, as the guaranteed rates increased. However, the existing mechanical model of the canal with the water delivery cannot fully consider the difference between the freezing and underwater non-freezing areas in winter, particularly for the continuity of soil. It is a high demand to combine the difference in shear stiffness between frozen soil and non-frozen soil. Pasternak model with two parameters can be expected to consider the soil continuity in the freezing area, whereas, the traditional Winkler model can be adopted in the non-freezing area. By contrast, the Winkler model with only a few parameters can be easily calculated for definite physical significance. In this study, the combined Winkler-Pasternak model was proposed for the frost-heaving mechanical analysis of the trapezoidal canal with water delivery in winter. Taking a trapezoidal canal with water delivery in winter in the Manas River basin in Xinjiang of western China as a prototype, the real normal frost-heaving amount, and subsidence deformation of the canal lining plate were also calculated using the improved model, Winkler and Pasternak model. Then, the bending moment was calculated with the upper surface stress of each section of the lining plate. The results indicate that the lining plate was divided into three parts of frost heave, subsidence and frost heavesubsidence transition section. Three models better represented the basic change trend of normal displacement of the lining plate. Meanwhile, the improved model was in better agreement with the measurement. A comparative analysis showed that the improved model was much more accurate than the traditional Winkler model in the freezing area, whereas, some errors but trivial differences were compared with the Pasternak model in the non-freezing area. Furthermore, the improved model shared the excellent performance of the Winkler model, such as simple calculation, clear physical meaning, and few required parameters. The bending moment of sections decreased rapidly in the freezing area with the increase of groundwater depth. The risk of frost-heaving damage to the canal lining plate was dramatically reduced at the groundwater level by appropriate drainage measures. The position in the frozen soil area of the lining plate easy to crack was located at 10.0%~23.3% of the lining plate length away from the waterline. The optimal operation conditions were adopted in the ice-free water delivery of the trapezoidal canal in winter. The improved model can be also applied to the ever-increasingly common situation of water delivery with the ice cover. The finding can provide a strong reference to design the frost heave resistance of the trapezoidal canal with water delivery in winter. [ABSTRACT FROM AUTHOR]

High-speed railways often run over underground metro stations. Dynamic load induced by high-speed train can influence the internal force of underground structure and hence can pose danger to the underground structure. Hence, it is necessary to estimate the safety of underground structure due to high-speed train load. In this paper, the effects of dynamic load induced by high-speed train on metro station are investigated by carrying out three-dimensional numerical analysis. Guinan high-speed railway, which is designed to run over Jinqiao metro station in Nanning, Guangxi province of China are adopted as the background of this case study. The hardening soil model with small-strain stiffness was adopted to model the behaviour of soil. Two typical speed of railway train (i.e., 160 km/h and 350 km/h) are considered in this study. Based on the numerical analysis, vertical vibration acceleration and bending moment of the structure of the metro station are presented and analysed. [ABSTRACT FROM AUTHOR]

Due to the complexity of pile–soil interaction, there is little research on active–passive piles that bear the pile-top load transmitted from the superstructure and the pile shaft load caused by the lateral soil movement around the pile simultaneously. The purpose of this study is to analyze the displacement and internal force of active–passive piles. Most of the pile design codes in China use the elastic resistance method to describe the relationship between the lateral soil resistance and the horizontal displacement of the pile, but this is not accurate enough to analyze the internal force and deformation of the pile when the pile displacement is large. For this case, the passive load on the pile shaft caused by the adjacent surcharge load can be described in stages, and the p–y curve method can be used to express the relationship between the lateral soil resistance and the horizontal displacement of the pile. Additionally, taking both the active load (vertical force, horizontal force, and bending moment on the pile top) and the passive load into account, the deflection differential equation of the pile shaft is herein established, and a corresponding finite difference method program is implemented to obtain the calculations pursuant to the equation. The correctness of the analysis method and program was verified by two test cases. The results show that our calculation method can effectively judge the flow state of the soil around piles and accurately reflect the nonlinear characteristics of pile-soil interaction. Moreover, the influence depth of the pile displacement under the passive pile condition caused by the adjacent load is significantly greater than that under active pile condition, and the maximum pile-bending moment appears near the interface of soft and hard soil layer. [ABSTRACT FROM AUTHOR]

The Wan Jiang Bridge in China was damaged by ship impact and subsequently restored. This paper presents a detailed evaluation of the residual service life (RSL) of the bridge using the reliability analysis method of the Joint Committee on Structural Safety, based on the structural load-bearing capacity (LBC) of the bridge and the design load. Data were collected from bridge design codes, field loading tests and finite-element (FE) analysis. The LBC was initially calculated and subsequently revised using specific coefficients. Using FE analysis, the bending moment on the control section of the bridge was determined under the most unfavourable loading conditions and the ultimate LBC of the bridge was checked. Subsequently, static and dynamic loading tests on the restored bridge were conducted, with the load and capacity determined for the control section based on FE analysis. The loads considered were dead load, vehicle load and crowd load. A time-dependent reliability index was developed for the restored bridge using the probability distributions of capacity and design load variables, and the RSL was determined. This case study, predicting the RSL of the bridge based on a multitude of data, should be valuable for future bridge maintenance and management. [ABSTRACT FROM AUTHOR]

The multi-row stabilizing piles have been applied in the stabilization of large-scale reservoir landslides in recent years. However, the mechanical behavior and deformation characteristics of the multi-row stabilizing piles reinforced reservoir landslides have rarely been investigated. This study takes the Taping landslide, a large-scale reservoir landslide in China, as a prototype. Two centrifuge tests were conducted to study the deformation and failure characteristics of the multi-row stabilizing piles reinforced reservoir landslide with two different row spacings. The result shows that the reservoir water level (RWL) drawdown operation induced the soil movement and high downslope driving force, further causing a significant increase in bending moments at the lower section of the piles, with peaking near the sliding zone; eventually, bending deformation and failure occurred more easily near the sliding zone. The downslope part of the piles can change the mechanical transmission behavior of the multi-row stabilizing piles in reservoir landslides. Small row spacing can enhance the mechanical connection between the rows of piles and raise the overall reinforcement capacity of the piles. The large row spacing weakens the mechanical connection between the rows of piles, and the mechanical states of the pile in different rows are relatively independent. As a result, the piles are easily damaged one by one from the first row to the last row, and the overall reinforcement capacity of the multi-row stabilizing piles is poor. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Harbin Institute of Technology. Social Sciences Edition / Haerbin Gongye Daxue Xuebao. Shehui Kexue Ban is the property of Harbin Institute of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Hydrogeology Journal is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To study the adaptation of the current automobile design load of highway bridges in China in case of separation of passenger cars and trucks, a statistical method is proposed in this paper to study the load data of special lanes for trucks. Four typical truck-based lanes were selected as the study object, from which information of continuous truck fleet was selected as the study of truck-specific lane load flow samples, and technical parameters of truck vehicles were determined. Finally, the load flow was introduced into simply supported bridges and continuous bridges of different spans, and the load effect at the control section was calculated and compared with the effect of the design load at the control section according to the current code. The results show that under the operation mode of "passenger car and truck separation," when the truck fleet passes through the simple support beam, the load effect at the control section generally does not exceed the effect of the vehicle load calculated according to the code design load. When the truck fleet passes through the continuous beam, the midspan bending moment of the continuous beam side span and the midspan bending moment of the middle span do not exceed the effect of the vehicle load calculated according to the code design load. However, the bending moment effect of the continuous beam support section exceeds the effect of the vehicle load calculated according to the design load of the code. To ensure the safety and durability of the bridge structure, the proposed lane load standard value is increased by 1.1 times and rounded up from the current Highway Bridge and Culvert Design Code. [ABSTRACT FROM AUTHOR]

The rapid development towards automated construction has been witnessed in recent years mainly due to the growing shortage of skilled labor. Against that backdrop, an accelerated method, with the aid of robotic cranes, is emerging in China to speed up the construction of industrial facilities such as warehouse structures. This method requires that the steel bars in the precast beams do not extend beyond the beam ends to facilitate the temporary fixation of the robotic crane at the top of cast-in-place columns. This, nonetheless, brings a series of new problems, one of which is how to choose a suitable anchoring type for the beam bottom bars. To address this issue, three large-scale exterior beam-to-column connections were fabricated and tested under lateral load reversals. Two anchorage forms, namely, mechanical splices and grouted sleeves, were adopted and compared with the monolithically cast specimen. The test results showed that the specimen using the grouted sleeves had similar seismic performance to that of the cast-in-place specimen, whereas the specimen using the mechanical splices presented significant post-peak deterioration under positive beam bending moments. This happened because the congestion of steel bars within the joint core made it difficult to fully tighten the beam bottom bars into the threaded couplers; consequently, a "slop" was formed which could substantially impair the cyclic behavior of the specimen. As such, it is suggested that grouted sleeves should be more applicable and reliable for the new construction method. This counter-intuitive finding also indicates that, for intelligent construction, no detail should be taken for granted, but rather needs due consideration. [ABSTRACT FROM AUTHOR]

Urban utility tunnels (UUTs) can significantly alleviate the problem of repeated excavation of traditional municipal pipelines and make full use of underground space resources. There are many challenges in the construction of UUTs in special soil areas, particularly in loess areas. The approach of a similarity model test is used to analyze the effect mechanism of loess stratum wetting on a UUT in detail. The stress variation and surface settlement of the joint and lining of the UUT under different wetting conditions are studied. The testing results demonstrated that the stress changes at the joints of a UUT are relatively uniform. The maximum value is 1.81 MPa, and meeting the requirements of the standard and the structural form of the joints will not affect the overall stability of the UUT. For the tunnel lining, the non-uniform subsidence caused by non-uniform wetting is the main reason for tunnel structure collapse and deformation. The bending moment and axial force near the collapsing region were larger than on the non-wet side. For the surface subsidence, that caused by full immersion is much larger than that caused by local immersion, with a maximum value of 48.24 mm. The existence and dissipation of the soil arching effect have an important influence on the surface settlement. [ABSTRACT FROM AUTHOR]

Improving coal resource mining rates has long been a focus of coal industry research. The gob-side entry retaining by roof cutting (GERRC) is a new coal mining technology that has gained popularity in China due to its high mining rate and safety. Based on the GERRC technology, the precise technical procedure is elaborated, and the fundamental idea of pressure relief is explored through creating a structural mechanics model of the surrounding rock in this paper. The results of mechanical analysis show that the primary mechanism of roof pressure release is to weaken the integrity of the roof, thereby reducing the ultimate bending moment of the rock stratum. In addition, an additional strategy for pressure release is suggested in this research, involving the weakening of the roof rock by the creation of dense pressure-released holes. The results of the engineering field experimentation demonstrate that the dense pressure-released holes can completely replace the conventional blasting technology of the past to achieve the effect of releasing the roof pressure, thus avoiding the use of hazardous and challenging-to-obtain explosives and demonstrating safety, reliability, and feasibility. [ABSTRACT FROM AUTHOR]

An innovative composite deck system has recently been proposed for improved structural performance. To study the fatigue behavior of a steel-concrete composite bridge deck, we took a newly-constructed rail-cum-road steel truss bridge as a case study. The transverse stress history of the bridge deck near the main truss under the action of a standard fatigue vehicle was calculated using finite element analysis. Due to the fact that fatigue provision remains unavailable in the governing code of highway concrete bridges in China, a preliminary fatigue evaluation was conducted according to the fib Model Code. The results indicate that flexural failure of the bridge deck in the transverse negative bending moment region is the controlling fatigue failure mode. The fatigue life associated with the fatigue fracture of steel reinforcement is 56 years. However, while the top surface of the bridge deck concrete near the truss cracks after just six years, the bridge deck performs with fatigue cracks during most of its design service life. Although fatigue capacity is acceptable under design situations, overloading or understrength may increase its risk of failure. The method presented in this work can be applied to similar bridges for preliminary fatigue assessment. [ABSTRACT FROM AUTHOR]

With the rapid development of transmission-line engineering in western China and the frequent occurrence of extreme natural disasters, a great deal of attention has been paid to the bearing capacity of foundation systems. The uplift capacity is still the controlling factor in the design, but neglecting the horizontal load component will induce great potential risks to the stability of the foundation. This paper describes the model test of rock-socketed piles (with soil overlying rock) that were subjected to axial and oblique tension impacts. Furthermore, the load displacement response, failure mode, and load transfer mechanism of the model piles were compared and discussed. The research indicates that the uplift capacity of the model pile under the oblique load can be remarkably reduced by up to 27.3% in comparison with the vertical uplift. Moreover, the load–displacement curve of the model pile under axial and oblique loads present abrupt failure. Notably, the failure mode under the axial tension is an inverted cone-shaped axisymmetric failure, and the failure mode under the oblique tension shows the wedge failure on the compression side and the interface separation on the tension side. The compression side and tension side show the opposite load transfer mechanism, thus inducing the presence of a bending moment in oblique tension pile. The position of the maximum bending moment occurs at the depth of 2.3–2.8d below ground surface. In summary, the research results of this paper have important guiding significance for design of transmission tower foundation in similar geological settings. [ABSTRACT FROM AUTHOR]

High steep landslides are a major concern for infrastructure construction in the mountainous areas of Western China. The micro-pile technique has been gradually used to prevent landslides, due to convenient construction and good performance. However, the application of the micro-pile technique on landslide prevention was generally implemented on the front edge of landslides, which is not applicable for the high steep landslides due to the limited operation space. In this study, a large-scale model test on the performance of a micro steep pile group on the prevention of high steep landsides was conducted in order to implement the micro-pile on the top of landslides. The force-deformation characteristics and failure modes of the steel pipe micro-pile group reinforcing high steep landslides were investigated. The test results showed that the landslide thrusts acting on the micro-pile group showed a triangle distribution. The maximum soil earth pressure was observed near the slip surface during landsides. The resistance of the micro pole group was distributed in an inverted triangle, mainly in the upper half of the loaded section. The sliding bed resistance is unevenly distributed along the height direction, and is larger near the slip surface. Once the landslide occurred, the force distribution of each row of steel pipe micro-piles was basically the same. The bending moment of the loaded section of the steel pipe micro-pile was mostly negative, with a larger bending moment in the range of eight times the pile diameter above the slip surface. The largest bending moment value is located at two times the pile diameter on the slip surface. On the other hand, the bending moment of the embedded section of the steel pipe micro-pile is mostly positive, showing a tension state with a maximum value at four times the pile diameter under the slip surface. This implies that the role of loaded and embedded sections of the micro-pile group on the landsides is different. The failure mode of the micro-pile group was mainly attributable to the bending failure within eight times the pile diameter above and below the slip surface. [ABSTRACT FROM AUTHOR]

High-filled cut-and-cover tunnels (HFCCTs) provide an ideal solution for reclaiming usable land in northwestern China due to the unique landforms of the Loess Plateau. To improve the safety and minimize the cost of such tunnels, most current methods focus on load reduction or a soil arching effect to reduce the earth pressure on cut-and-cover tunnels (CCTs). Although optimizing the design of HFCCTs is an important topic, very few studies have focused on modifying the cross-section of CCTs to improve their design. The modifications of cross-sectional design were proposed, and the vault optimization factor, F, was introduced. The optimal cross-sectional design of a CCT was determined using the finite element method. The experimental results verify that changes to the cross-section of a CCT’s lining structure can both reduce the required thickness of the CCT’s structure and increase the allowable backfill height above the CCT. The optimization is accomplished by modifying the cross-sectional design of a CCT to minimize the bending moment and allow the CCT to carry a more axially compressive load. [ABSTRACT FROM AUTHOR]

To further improve the transportation level of China's high-speed railway, it is urgent to research on the key technology of speed in for the existing 250 km/h high-speed railway. The track structure directly bears the train load, the adaptability of the track after the train speed increase is an important factor affecting the safe and stable operation of the train. Based on the field investigation, finite element analysis, numerical calculation and other methods, this paper studies the adaptability of ballasted track, ballastless track and designed track superelevation, and the technical conditions for the speed-increase track of 250 km/h high-speed railway are put forward. The main conclusions are as follows: the speed increase of ballasted track lines will cause the increase of dynamic indexes of the fastener and track bed, which will reduce the service performance of structures; the speed increase of ballastless tracks will cause the increase of the longitudinal and transverse bending moments of track slab and concrete base slab, and the longitudinal bending moment of track slab in subgrade section increases the most, which is 4. 7 kN · m/ m; considering the safety margin, the reinforcement of track slab and concrete base slab in the subgrade, bridge and tunnel sections meets the requirements of strength and crack width; after the speed increases, the track design curve superelevation should be adjusted to meet the requirements of minimum curve radius and transition curve length under different speed levels; after the speed increase, attention should be paid to the drainage of track slab structure, track smoothness, etc., and the relevant requirements of the current specifications should be satisfied. [ABSTRACT FROM AUTHOR]

Copyright of Advanced Engineering Science / Gongcheng Kexue Yu Jishu is the property of Advanced Engineering Science Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A large number of drainage pipes and canals in China have been in disrepair for a long time and there have been problems such as leakage and corrosion. In response to these problems, this paper studies a non-excavation technology for repairing the arched canal structure—the in-situ spraying method. To study the influence of the original canal structure on the mechanical characteristics of the lining structure by in-situ spraying and the restraint effect on the lining structure, a field model test with a similar ratio of 1:2 was conducted in the field test pit. By conducting four stages of three-point concentrated load loading tests, the mechanical characteristics of the lining structure were investigated to reveal the influence of the canal structure on the force of the lining structure. The test results show that: the maximum crack width of the newly added lining structure is 0.27 mm and the normal service ultimate bearing capacity of the arched structure repaired by H-70 reaches 150 kN; comparing the loading test and the numerical simulation results, the difference between the two vault displacement results is 4.65% and the results are relatively consistent. The displacement of the bottom of the lining structure is small and the participation of the bottom plate is small, while the displacement of the upper arch structure of the lining is significantly larger than the lateral displacement, indicating that the canal structure can effectively limit the lateral displacement of the newly added lining and that the canal structure is greatly reduced. The bending moment of the lining structure is improved and the restraint effect on the arch foot is more obvious. This paper proposes the use of H-70 to repair arched canal structures by the in-situ spraying method and seeks to prove the feasibility of this method and fill the gap of research in this area. This paper provides the structural design basis and experimental knowledge for the construction of the repair method, which has important practical significance for the pipeline repair project in the future. [ABSTRACT FROM AUTHOR]

Rice–crayfish rotation expanded rapidly in China, as it provides considerable profit and reduces pesticide application. This study investigated the impact of different mechanical transplanting methods and planting geometry on the yield and lodging resistance of an indica rice variety under a rice–crayfish rotation system in 2018 and 2019 in Hongze Lake district, using an excellent-quality variety Taoyouxiangzhan. Seedlings were mechanically transplanted using two mechanically transplanted carpet seedling (MTCS) with equal spacing (30 cm) at five spacings and mechanically transplanted pot seedling (MTPS) with wide and narrow rows (23 cm + 33 cm) at five spacings. The yield of MTPS was 8.3% higher across 2 years under the most optimum density than MTCS using the same density, mainly due to a significantly increased number of spikelets per panicle. Accompanied by the decrease in planting density, rice yield first increased and then decreased under each mechanically transplanting method, and reached the maximum in the A4 and B4 treatments (63.9 × 104 seedlings ha−1), respectively. Compared with MTCS, MTPS significantly increased the fresh weight of single stem, plant height, gravity center height, ear weight, length and area of the upper three leaves, so as to increase the bending moment at basal internodes by whole plant (WP), while it also increased the stem diameter, wall thickness and stem and leaf sheath dry weight per unit length of the second internode at the base, resulting in a significant increase in the force applied to break the base segment (F) and the bending moment of whole plant (M). The higher increase percentage in M than WP led to a decreased lodging index. The lodging index of both mechanically transplanting methods reduced with declined planting density in virtue of the improved breaking load of the basal internode, and it was primarily a result of increased stem diameter, wall thickness and plumpness of basal internode. The balance between the high yield and lodging resistance of Taoyouxiangzhan under a rice–crayfish rotation system can be realized at 63.9 × 104 seedlings ha−1, with MTCS at 15.7 cm plant spacing and MTPS at 16.8 cm. Generally, MTPS showed obvious advantages in yield and lodging resistance than MTCS. [ABSTRACT FROM AUTHOR]

The floating platform-mooring system-pile-soil interactions under wave loadings represent a complex yet understudied aspect of floating offshore wind turbines (FOWTs). This paper presents the development and application of an Incompressible Material Point Method-Finite Element Method-Material Point Method (IMPM-FEM-MPM) model to simulate these interactions for a triangle-shaped semi-submersible platform (Tri-SSP), which serves as the foundation of China's first deep-sea FOWT, named 'Fuyao.' The proposed model is validated by studying the hydrodynamic responses of the OC4-DeepCwind platform. Under regular waves, increasing wave heights lead to heightened motion amplitudes, with the Tri-SSP exhibiting distinct phase differences between surge, pitch, and heave motions. Anchor Group 1 experiences significant peak tensions, ranging from 2.26 MN to 4.47 MN, which influence soil displacement, shear forces and bending moments along the pile shaft, emphasizing the impact of wave loading on pile-soil interactions. Under 1-h irregular waves, tension in Anchor Group 1 reaches extreme levels, with tensions up to 8 MN observed, underscoring the critical role of mooring systems in mitigating wave-induced forces. The calculated maximum stress within the pile indicates the structural integrity of the DH36 steel pile under these conditions. Comparisons of hydrodynamic responses, both with and without pile-soil interactions, show minimal discrepancies in motion amplitudes, indicating a minor influence on the dynamics of the platform and mooring system. These findings contribute to the understanding of complex interactions in deep-sea FOWTs, informing design and operational strategies for enhanced stability and performance. • The IMPM-FEM-MPM model properly evaluates platform and mooring hydrodynamics. • Hydrodynamic responses of a triangle-shaped semi-submersible platform are examined. • The wave-floating platform-mooring system-pile-soil interactions are analyzed. • The deflection and stability of piles are greatly influenced by the mooring system. • Impacts of pile-soil interactions on platform and mooring hydrodynamics are minor. [ABSTRACT FROM AUTHOR]

• Shear tests evaluating behavior of Fe-SMA/steel single lap joints are conducted. • Effects of adhesive types, adhesive layer thicknesses and overlap lengths on the interfacial behavior are investigated. • Distribution of surface strain and interfacial shear stress are obtained, and the effective overlap length of the single lap joints is assessed. • Load-transfer mechanisms and damage evolution process are discussed. • Cohesive zone models with different adhesive types and adhesive layer thicknesses are established. The activated iron-based shape memory alloy (Fe-SMA) can introduce considerable prestress in the damaged zone of deteriorated steel structures through bonding technologies. In China, it has been successfully applied to several kilometer-span steel bridges, such as Sutong Bridge and Hangzhou Bay Bridge. The shear and interfacial performance of steel-to-Fe-SMA plates are crucial issues in bonding Fe-SMA to reinforce deteriorated steel structures, which remain unclear. This paper investigates the shear characteristics of Fe-SMA/steel single lap joints (SLJs), considering the effects of adhesive types, adhesive layer thicknesses and overlap lengths. The stress distribution and the interfacial shear stress at the overlap zone are obtained through experiments, and the damage evolution and load-transfer mechanisms of adhesive layers are analyzed. The experimental outcomes indicate that the maximum tensile stresses of Fe-SMA plates can reach 61 % of their ultimate strength. The failure modes and ultimate load of Fe-SMA/steel SLJs are affected by adhesive types. Interface failure occurs in CH 120 and PCMdur™-15 specimens, whereas interface, cohesive and mixing failure are formed in Sika 31 specimens. Due to the adverse effects of adhesive layer defects, out-of-plane bending moment, and damage accumulation of the adhesive layers, the distribution of surface strain and interfacial shear stress of all specimens are mainly at the effective overlap zone. For an efficient engineering design, the linear and polynomial fitting models of cohesive zone models with different adhesive types and adhesive layer thicknesses are proposed based on experiments. The experimental and theoretical achievements can provide design recommendations for deteriorated steel structures rehabilitated by bonding Fe-SMA. [ABSTRACT FROM AUTHOR]

• The wooden drum-tower exhibits poor ductility, and the premature withdrawal of tenon-mortise joints in components adjacent to the failure zone is a triggering factor for the collapse of the structure. • After component failure, the structure undergoes internal force redistribution. The beam in the failure zone is forced to bear tension, bending, and torsion simultaneously, leading to the failure of the tenon-mortise joints. At the moment of mortise-tenon joints failure, the columns within the failure zone gradually tilt under the influence of gravity, eventually leading to progressive collapse. • The failure of mortise-tenon joints in the failure zone is characterized by compression deformation of the tenon in the transverse direction and splitting of the mortise edges. Non-collapsed structure tilts as a whole, with slight detachment of tenon heads and uplift of column bases. The drum-tower belongs to the category of towering structures, and the overall collapse is a common accident in such structures. In order to study the anti-collapse performance of drum-towers, this research used the bottom floor of a wooden drum-tower in the southwest China as a prototype, designing and producing a 1/3 scale structural model. The sudden-column-removal (SCR) method was employed to simulate the structural collapse process, observe collapse characteristics, and analyze the dynamic response of the structure. A finite element model was established, and on the basis of verifying its accuracy, a parameter expansion analysis was conducted. The study indicates that the ductility of wooden drum-towers is relatively poor, and the pulling out of mortise- tenon joints in adjacent components in the failure area is a primary factor for the progressive collapse of the structure. Due to the redistribution of internal forces, the load-bearing status of beams in the failure area changes, experiencing tension, bending moment, and torsion simultaneously, leading to the pulling out, compression, and splitting of mortise-tenon joints. After the failure of these joints, the structure undergoes progressive collapse under the influence of gravity. The dimensions of mortise-tenon joints and the friction coefficient have a significant impact on the anti-collapse performance of the structure. Larger dimensions and friction coefficients result in slower structural damage and more stable structural response. Among these factors, increasing the depth of mortise-tenon joints has the most significant effect. [ABSTRACT FROM AUTHOR]

Poor light stress causes lodging risks in hybrid indica rice (Oryza sativa L.) in Sichuan Basin, China. However, the effective way of improving lodging resistance of hybrid indica rice by plant regulation strategy under poor light stress has not yet been investigated. A 2‐yr field study, comparing the three foliar application uniconazole rates under normal light and shading condition, was conducted to determine the lodging resistance and its physiological mechanism by using two hybrid rice varieties (Yuxiang203 [YX203] and Cliangyouhuazhan [CLYHZ]). The results showed that shading significantly decreased grain yield, but, increased lodging index (LI) due to poor stem breaking strength (M). Also, shading increased the non‐structural carbohydrates (NSC), but reduced structural carbohydrate (SC), especially for lignin in basal culm and thus, weakened the stem stiffness. Grain yield was first increased, and then declined with increasing foliar uniconazole rates. And, LI decreased sharply owing to improvement of M while reduction of bending moment by whole plant (WP). Larger section modulus (SM) of YX203 and higher bending stress (BS) of CLYHZ were contributed to higher M. Correlation analysis showed that M was significantly correlated with culm diameter, culm wall thickness and SC content for YX203, and that with SC content for CLYHZ, respectively. The results indicated that foliar application of uniconazole increased lodging resistance of hybrid indica rice for larger M and SC accumulation in basal stem. Uniconazole foliar application at 40 mg L–1 can increase lodging resistance while maintaining grain yield of hybrid indica rice in the Sichuan Basin, China. Core Ideas: Shading rapidly raised lodging risks of hybrid indica rice due to poor stem strength of basal stem.The foliar application uniconazole increased lodging resistance of hybrid indica rice.The higher stem strength of Yuxiang203 rely on section modulus and structural carbohydrates.Uniconazole rate at 40 mg L–1 rose lodging resistance and yield of hybrid indica rice in the Sichuan Basin. [ABSTRACT FROM AUTHOR]

During the construction of deep-buried diversion tunnels, many uncertainties exist in the variables governing the safety of the support structure, which will affect the safety of the tunnel. Therefore, the probability analysis of the deep tunnel based on Monte Carlo simulation is analyzed. For that a case study of diversion tunnels at Jinping II hydropower station, southwestern China is selected and analyzed. First, the dispersions of geostress and marble mechanical parameters are studied based on the field monitoring of the bolt stress and the laboratory testing of the Jinping marble. Subsequently, the statistical characteristics of the radial subgrade modulus are obtained considering the 100,000-fold sampling. Finally, the influence of the main uncertain factors on the internal force and deformation of the supporting structure is examined through the establishment of a numerical model. The maximum bending moment and axial force appear in the vault and invert of the tunnel, respectively. When the design requires the reliability of the tunnel support structure to achieve 90% in the case of Jinping II hydropower station, the value of the bending moment and the axial force cannot be higher than 0.57 MPa and 8.0 MN, respectively. The factors those having a greater impact on the safety of the tunnel support structure are the vertical load and the radial subgrade modulus. [ABSTRACT FROM AUTHOR]

Y-shaped piles are a new type of pile whose cross-section is like the letter Y: they are often used in ground improvement for road or train subgrades in the eastern coastal region of China. To investigate the bearing behaviour of Y-shaped piles in saturated sand, a series of model tests under compressive and horizontal load for Y-shaped piles, C 1 circular pile (the same cross-sectional area of Y-shaped pile), and C 2 circular pile (the same perimeter of Y-shaped pile) were carried out. Comparative analysis was conducted on bearing capacity, axial force and side resistance distribution, load sharing ratio, bending moment, and lateral soil pressure distribution along the embedded length. The results show that the bearing capacity of a Y-shaped pile does not increase in proportion, and the shaft resistance is weakened to some extent in saturated sand; Y-shaped pile can effectively improve the compressive bearing capacity for the same amount of concrete. The lateral bearing capacity of a Y-shaped pile has directionality, and hanging a circular section into a Y-shaped section may improve the horizontal bearing capacity for the same amount concrete, but cannot give full play to the advantage of the larger side area for horizontal bearing capacity in saturated sand. [ABSTRACT FROM AUTHOR]

At present, specific earthquake motion is often used for analyzing the influence of trains on high-speed railway structure; however, the uncertainty of earthquake motion is rarely taken into consideration. In this study, on the basis of considering the uncertainty of earthquake motion, and taking a simply-supported beam with CRTS II track system and CRH2 high-speed train in China as the research objects, a finite element analysis model of vehicle-bridge coupled model was established and verified by tests. The influencing mechanism of the trains on structural response under the action of uncertain earthquake was analyzed, and the range of the influence levels of trains on seismic response of structure was calculated. The research findings show that under the effect of earthquake, the presence of trains decreases the responses of piers and bearings, while increases the response of track structure. With increasing peak ground acceleration, the effect of trains on the track structure deformation increases, while that on the bending moment of piers, shearing force, and bearing deformation all decrease. The increase in train speed will not significantly affect the seismic response of structures. The ratio of seismic response between the operating conditions with and without vehicles was kept within a certain range, so that the demand range for seismic response under the operating condition with vehicles can be approximately simplified. [ABSTRACT FROM AUTHOR]

This paper describes the seismic performance of a steel frame with additional LYP steel dampers. LYP steel dampers provides passive energy dissipation device in a structure, it also reduces the lateral forces in efficient way which is produced by seismic wave. The seismic performance of structures is needed in the design of structure, especially in countries where seismic activities occur. This analysis is accomplished with the FEM and software called SAP2000. The steel frame is only analyzed using numerical simulation. This paper describes two steel frames, the first steel frame is a two story steel frame without LYP steel dampers while the second steel frame has with LYP steel dampers. The seismic mechanism analysis was accomplished with the help of nonlinear time history analysis technique and the results for inter-story drift, steel frames, base shear, the displacement of the top story and the stress of the dampers was obtained. The time history analysis was taken out with three different earthquake waves according to the Chinese code for the seismic design of buildings; the earthquake waves were divided into the three different earthquake levels in China which include the frequent, moderate and rare earthquake level. The seismic mechanism analysis was accomplished on the three different earthquakes and three different earthquake levels in China. The modal analysis was taken to obtain the frequency and the period of the steel frames. The steel frames were examined under the different load combination which is also described in the code for the seismic design of buildings to obtain the internal forces of the members of the steel frame which include the axial force, shear force and bending moment. The different load combinations are used to get the stress of the dampers. We notice that the addition of LYP steel dampers increases the seismic resistance of the steel frame as we can observe by a reduction in the displacement of the top story, base shear, and inter-story drift angle by the addition of LYP steel dampers on the steel frame. We can be able to observe the behavior of the frames under the different earthquake levels in China using the pushover analysis. [ABSTRACT FROM AUTHOR]

Passive tuned mass dampers (TMDs) have been increasingly investigated for vibration control of wind turbines. However, TMD designs based on individual or a few operating conditions may result in insufficient consideration of the TMD's impact on wind turbines. For instance, the influence of end-stop collision forces on the main structural damage may be significantly underestimated, thereby affecting the overall lifecycle evaluation. In this study, focusing on large offshore fixed-bottom monopile wind turbines, we propose an integrated TMD design methodology taking the damper displacement constraints into full account. A comprehensive optimization of the passive omnidirectional pendulum-type TMD is conducted considering large number of operating conditions in the offshore environment. Next, a real-world application of the optimally designed TMD is performed for a 6450 kW monopile offshore wind on the Yellow Sea, China. We develop an on-site testing methodology and evaluation criteria for assessing the effectiveness of the TMD offshore. The results of resonance, emergency stop, operatingand reliability test conditions demonstrate the following: under the optimized TMD design taking into account all operating conditions, the TMD with a mass ratio of 1.56% can offer added damping in the fore-aft and side-side directions of the turbine, and provides the desired damping ratio of 1%; within a 4% frequency range around the design frequency, the TMD achieves effective vibration control; at rated power, the TMD achieves a reduction of more than 50% in the amplitude of the tower base side-side bending moment (Mx). The integrated TMD design with displacement constraints allows for the optimal TMD design across all operating conditions, thereby achieving superior overall vibration control and reduction in fatigue loads. The successful real-world application of the TMD based on integrated design methodology is of high value to the research community. • An integrated design method proposed for offshore wind turbine TMD considering damper displacement constraints. • An overall optimal TMD is obtained covering full operating conditions with performance and cost balanced. • Successful real-world application of the in-house designed and manufactured TMD in a 6.45 MW monopile wind turbine. • The effectiveness of TMD assessed through on-site tests conducted under various conditions. • Analysis of large amount of data from long-term measurement confirms the reliability of the designed TMD. [ABSTRACT FROM AUTHOR]

In recent years, massive interbedded sandstone and slate anti-dip slopes have been discovered in the southwest and northwest regions of China. The distinct mechanical properties of different rock layers make these slopes particularly unique. In this paper, the finite-discrete element method (FDEM) is used to study the toppling failure mechanism of soft-hard interbedded anti-dip rock slopes (SHIADRSs). Firstly, the numerical model of soft-hard interbedded anti-dip rock slope (SHIADRS) is established based on a centrifugal loading test. Then, the stress state, evolution of displacement and cracks, and progress of toppling failure in the SHIADRS are analyzed. Besides, the effect of rock structure, slope angle, dip angle, and rock mechanical properties on the toppling failure of SHIADRS is discussed. The simulation results show that the toppling failure process of SHIADRS can be divided into three stages. The stress distribution in hard rock (HR) is obviously different from that in soft rock (SR) layers. HR layers bear greater bending moments than HR layer during the toppling failure of the soft-hard interbedded anti-dip rock slopes. In addition, the stability of SHIADRS is negatively correlated with the slope angle and the dip angle of rock layer. Compared to the inclination angle of rock layers, the slope angle has a more significant impact on the stability of slopes. The internal friction angle of the rock layer has almost no effect on the toppling failure of SHIADRS. [ABSTRACT FROM AUTHOR]

Coal mining-induced ground subsidence often causes buried oil-gas pipeline failure. Insight the evolution of pipeline failure length and inflection points under the influence of adjustable factors (the distance between the panel pipe, panel width, internal pressure, and burial depth) has become increasingly essential for pipeline maintenance and operation. At present, the pipeline's failure length, failure time series, and inflection point distribution in subsidence areas are vague, which is not perfect in terms of specificity and clarity. Thus, a novel method to distinguish local failure and inflection points of pipelines is proposed by combining its moment and volume strain. Taking Panel 22102 of Ordos in western China as an example, the pipeline failure length and time series characteristics, as well as the inflection point spacing (IPS) are analyzed under the influence of adjustable factors by numerical simulation. The results show that (ⅰ) By increasing the distance between the panel pipe, and reducing the panel width, burial depth, and internal pressure, we can effectively mitigate or prevent pipe failures. For Panel 22102, the distance between the panel pipe should be less than 120 m to prevent failure. When it is unavoidable for the panel to pass underneath the pipeline, the width of the panel needs to be reduced to less than 120 m. (ⅱ) The pipeline failure length decreases by 2.9% for every 10 m reduction in the panel-to-pipeline distance. For every 10 m reduction in panel width, the pipeline failure length decreases by 5.7%. For every 0.1 m decrease in the burial depth, the pipeline failure length decreases by 2.16%. For each 1 MPa increase in internal pressure, the pipeline failure length increased by 0.48%. (ⅲ) The IPS is proportional to the panel width, burial depth, and internal pressure while exhibiting an exponential relationship with the distance between the panel and pipe. (ⅳ) The failure first spreads from the pipeline's subsidence center towards both ends, followed by spreading from both ends and the center towards inflection points simultaneously. (ⅴ) A multi-level and multi-faceted resilient management and collaborative operating pattern is established for the gas-coal integrated mining field. The research results provide scenario guidance and decision support for managers to develop adjusting measures to maintain pipelines, and also promote the coordinated mining of gas and coal resources. • The method was established to judge pipeline local failure and inflection points. • The length, proportion, and time series of pipeline failures were elucidated. • The inflection point and bending moment of the pipeline were clarified. • Multi-level and multi-faceted pipeline management schemes were proposed. [ABSTRACT FROM AUTHOR]

Project Oufei is the largest individual reclamation project in Wenzhou city, China, and the main infrastructure consists of seawalls, sluices and separation dikes. These infrastructures face repeated horizontal forces from wind and waves; thus, it is essential to evaluate the lateral bearing of single pile used for sluice gates. This paper presents a case study on lateral monotonic and cyclic behaviour of bored piles in soft soils. Four instrumented piles were loaded monotonically and cyclically to assess the contribution of soil improvement by vacuum preloading with prefabricated vertical drains. The test results show that the ultimate horizontal capacities were 200 kPa and 100 kPa for piles in the treated zone and untreated zone, respectively, under monotonic loading and up to 220 kPa and 120 kPa for piles in the treated zone and untreated zone, respectively, under cyclic loading, indicating that the ultimate horizontal capacity of piles in the treated zone can meet the design requirement of 130 kPa. Moreover, soil improvement decreased the maximum bending moment of the bored piles and enhanced the pile head stiffness, and the influence depth of soil improvement is up to 10 m. This indicates that soil improvement by vacuum preloading with prefabricated vertical drains is effective and can be used for lateral loading in reclamation project. [ABSTRACT FROM AUTHOR]

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With increasing traffic volume, the traffic load grade given by design codes has gradually increased. For new bridges, there is no problem, and the traffic load can be met through the requirements of the new code. However, for existing bridges, there is a lack of uniform standards on whether they can continue to be used. It is not clear whether these bridges will be judged according to the new code or the original design code. The traffic loading effects of different codes on medium- and small-span girder bridges in China are investigated in this study. Three codes are introduced: JTJ 021-89, JTG D60-2004, and JTG D60-2015. Simply supported girder bridges and continuous girder bridges are discussed. The traffic loading effects calculated based on JTG D60-2015 are significantly larger than those calculated based on JTJ 021-89. For simply supported girder bridges, most of the differences range from 20% to 40%, and the maximum value is almost larger than 60%. For continuous girder bridges, most of the differences in the positive bending moments are concentrated in the 20%∼40% range, while the differences in the negative bending moments range from 10% to 20%. Therefore, the differences in traffic loading effects calculated based on various codes cannot be ignored in actual bridge engineering. The conclusion in this study can provide a basis for bridge structure evaluation and life prediction. [ABSTRACT FROM AUTHOR]

The Yuanzishan landslide is an unstable slope in Langzhong County, located in northeast Sichuan province, China. The Guangyuan-Nanchong expressway passes through the front edge of the unstable slope, and subgrade excavation has resulted in slope deformation, which threatens the safety of the highway construction. Emergency landslide control requires reduction of the slope disturbance. This study aims to investigate the use of buried-boring piles as a potential method for emergency landslide control. A simplified calculation method was used for the design of the buried-boring piles, according to the limit equilibrium of the soil and the elastic foundation coefficient method. The measured internal force changes of the pile were compared, in order to determine the distribution coefficients of the driving force. A relationship between the driving force of the shared pile ratio and the buried depth ratios was then established. Furthermore, a variety of factors affecting the internal forces of the buried-boring pile and the lateral reaction of the soil were also studied. The results revealed that (1) there was a quadratic relationship between the driving force of the pile-shared ratio and the sliding depth ratios; (2) the maximum bending moment of the pile increased with an increase in the sliding depth ratio of the pile, following a power law relationship; (3) increasing the buried depth of the pile head reduced the influence of the pile diameter on the maximum internal forces; (4) increasing the pile diameter decreased the maximum lateral reaction of the soil. The buried-boring piles can be used in similarly unstable regions for emergency control of deforming slopes. [ABSTRACT FROM AUTHOR]

It has generally been believed that the serious seismic damage of tunnel mainly occurred in portal section and fault dislocation zone. However, the survey of seismic damage showed that the seismic damage of tunnel also mainly occurred in geological section at interface of soft and hard rock. Currently, merely scholars have made some research studies on characteristics of seismic damage and damping technology of tunnel crossing the vertical interface between soft and hard rock in high intensity area, and the mechanism of seismic damage has not been clearly revealed. Therefore, based on the Urumqi Metro Tunnel project in China, a three-dimensional six-degree-of-freedom shaking table model test was carried out. Through comparative analysis of peak ground acceleration (PGA), displacement difference at the interface between soft and hard rock, and structural safety factor under 5 kinds of conditions, the seismic damage characteristics of tunnel crossing interface of soft and hard rock were revealed, and a new damping technology of absorbing joint was proposed. The following findings can be drawn. (1) The seismic damage of tunnel is mainly affected by stratum inertial force under the homogeneous stratum of soft rock. The seismic damage of tunnel is mainly caused by the forced displacement (the displacement difference between the two sides of interface of soft and hard rock), followed by stratum inertial force under the geological condition of interface between soft and hard rock. (2) The conventional type of absorbing joint (only the second lining is set with absorbing joint) is used in tunnel lining structure, and the damping ratios of principal tensile stress, bending moment, and axial force of lining are above 47.5%, 40.7%, and 72.7%, respectively. Compared with conventional type of absorbing joint, the damping effect of new type of absorbing joint (staggered absorbing joints of primary support and secondary lining) is 19.9% higher than that of conventional type. (3) The new type of absorbing joint is recommended for tunnel crossing interface section of soft and hard rock. The specific implementation suggestions are as follows: the setting interval of second lining absorbing joint is the same as the length of lining formwork trolley, and the interval of primary support absorbing joint can be set according to excavation footage length. The filling materials in second lining absorbing joint can be shared with the rubber waterstop set in construction joint, and the primary support absorbing joint can be realized by injecting mixtures of rubber particles and shotcrete. [ABSTRACT FROM AUTHOR]

For tunnels excavated in soft layered rock strata, the secondary lining is susceptible to asymmetrical pressure and substantial concrete cracking. To solve this problem, a supporting system that combines a secondary lining with a highly deformable layer is proposed. First, field investigations were conducted to reveal the mechanical behaviors of the secondary lining of two typical tunnels situated in phyllite formation in China. Then, similarity model tests were used to analyze the mechanical responses of the secondary lining in layered rock stratum with different inclination angles. Finally, numerical simulation was adopted to systemically investigate the yielding mechanism of yielding layer in different cases. The results show that: (1) The distribution of inner force and deformation of lining is non-uniform due to the anisotropy of rock mass and geo-stress field, with the positive bending moment and larger axial force appearing mainly in the region where the tangent of the tunnel contour is parallel or vertical to the weak planes, respectively. (2) The existence of yielding layer has no influence on the distributed feature of inner force and displacement around tunnel perimeter, while it can significantly lower the magnitude of inner force and displacement of the lining. (3) The distinctly compressive zones of yielding layer coincide with the zones of positive bending moment, and the line connecting the central points of the evidently compressive zones on both sides will deflect towards the direction of minor principal stress to a certain extent. (4) The inner force and deformation of lining increase with the increase in the strength or decrease in the thickness of yielding layer, and this changing trend is related to the different supporting curves for linings with yielding layer of different strength and thickness. [ABSTRACT FROM AUTHOR]

High-filled cut-and-cover tunnels (HFCCTs) are common in northwestern China because their construction allows usable land over the CCT to be reclaimed. However, due to the unique landforms of the Loess Plateau in this region of China, the amount of backfill soil that is needed for HFCCTs is enormous, and the backfill must be high enough to maximize the usable land. Currently, the main challenges for the construction of HFCCTs are ultrahigh earth pressure and safety concerns related to the existing CCT lining structure. This paper discusses physical modeling tests that were conducted to investigate (1) load reduction methods that utilize expanded polystyrene (EPS) in the backfill soil; and (2) structural modifications to CCTs. The experimental results agree well with the numerical analysis results. The numerical analysis helped to determine suitable thicknesses of EPS material for load reduction when the CCT was subjected to different backfill heights. Also, by modifying the cross-sectional shape of the lining structure of CCT, the internal forces could be altered to make the concrete structure support more compressive loads rather than succumb to bending moments. This study found that the coupled effects of load reduction using EPS and cross-sectional modifications of the CCT lining structure can significantly reduce the required thickness of the CCT lining structure, enhance the safety of the CCT, and increase the allowable backfill height. [ABSTRACT FROM AUTHOR]

Net enclosure aquaculture is a newly developed eco-friendly marine aquaculture method and has been applied extensively in China because of the advantages of large water body, wide space for fish activities, closer to nature culture environment and closer to wild culture objects. Pile-type and floating-rope-type are two main construction types of enclosure engineering, and the pile-type is more preferable owing to its higher performance in withstanding harsh ocean environment. The pile-type aquaculture engineering consists of net panel system and pile system configured in mono or multi rows. In practice, the overturn and breakage of the piles have occurred and lead to the escape of cultured fishes, resulting in great economic loss. In order to solve these problems and improve the stability and safety of piles, the mechanical characteristics of piles in marine dynamic environment were analyzed in this study, and the pile-type aquaculture site located at Taohua island, Zhoushan was chosen as the study case. The subgrade reaction method, representing the soil surrounding of the pile by a series of discrete horizontal springs was adopted to investigate the effects of water depth, current velocity, wave height and combined action of wave and current, together with the embedded depth on the dynamic response of piles. The results showed that the maximum displacement was found at the top of the pile and increased with the increase of current velocity, wave height and water depth, and decreased with the increase of embedded depth. The positive and negative bending moment in the sides of the vertical line of zero bending moment increased first and then decreased along the pile, showing a shape of symmetrical S. The maximum bending moment was found about 2 m underneath the sea bed and exhibited a similar dynamic tendency to that of the maximum lateral deflection. As for the case of pure current, the piles kept stable and safety at the current velocity of 0.8, 1.0, 1.2 and 1.5 m/s. However, it could be damaged when the wave height exceeded 5 m or in the combined action of wave height of 3.0 m and current velocity of 1.0 m/s. For the engineering case in this study, the embedded depth should be larger than 17 m when the wave height of 5 m was considered as the lateral loading. In addition, a ratio of the length above the sea bed surface and embedded in the sea bed of the pile not more than 0.8 was advisable. Filed observation of the piles lateral deflection and stress force should be monitored in a long period so as to improve the analytical method specially used for net enclosure engineering. The results can provide guidance for the net enclosure design and construction. [ABSTRACT FROM AUTHOR]

A new form of retaining system for use in deep excavations in crowded cities is proposed in this paper. The new system, which we have coined the herringbone retaining system (HRS) involves the use of vertical and batter piles, capping beams, and wales. A numerical study was conducted (using the finite difference tool FLAC3D) to investigate various aspects of the behavior of the new system and reveal the mechanisms responsible for it. The HRS method was compared subsequently to two other commonly-used systems: the cantilever retaining structure (CRS) and horizontal-strutted retaining structure (HSRS). The results show that using the HRS method significantly reduces the deformation of the vertical piles and bending moments acting on them. More specifically, the maximum values of the deformation and bending moment were calculated to be 4.5% and 23.1% of the corresponding CRS values, respectively (the corresponding figures calculated for the HSRS method are 5.3% and 19.7%, respectively), so the HRS and HSRS methods provide similar levels of support. Finally, a real-world application of the system was presented to provide a valuable reference for the future use of HRS. [ABSTRACT FROM AUTHOR]

Square confined concrete arch is increasingly used in deep soft rock roadway support because of its advantages of high strength and construction convenience. However, the design of confined concrete arch in underground engineering still remains in experience-based method and lacks quantitative analysis. As a connecting component between arch sections, the connection joints have an important influence on the internal force distribution and failure mechanism of support arch. Therefore, a reasonable design of arch joints is the premise of rational support design. Taking Liangjia Coal Mine, a typical deep soft rock mine in China, as research background, this paper fully compared the most widely used joint types of confined concrete arch as analytical objects: flange joints and casing joints. The main failure modes of these two kinds of joints under bending moment are defined. Laboratory and numerical tests are carried out to study the mechanical characteristics of joints. Based on the M–θ curve, the influence law of different design parameters is analyzed, and the design principles of joints are proposed. The research results could provide a theoretical basis for the design and application of confined concrete arch in related projects. [ABSTRACT FROM AUTHOR]

During the construction of suspension bridges, the stress state of the pylon (tower) is improved by pushing the pylon saddle by an appropriate distance at the proper time. An analytical algorithm for the assessment of the required timing and displacements for the pylon saddle pushing at particular construction stages is proposed and verified in this study. The timing calculation is based on the assessment of current hanger tensile forces at each construction stage and the pylon stress state, while the pushing distance/displacement is derived from the conditions of elevation difference closure and the conservation of unstrained length of the main cable segments. This algorithm was successfully applied during the construction of a particular suspension bridge in China with a main span of 730 m. The results obtained strongly indicate that the bending moment in the pylon bottom is contributed by both horizontal and vertical forces of the main cable. The horizontal constituent is dominant and its share gradually increases in the bridge construction process. In a suspension bridge with side spans of various lengths, the stresses in the pylon bottom on the side with a larger side span is more likely to exceed the limit. Therefore, the respective strength criterion controls the pylon saddle-pushing schedule. The proposed analytical algorithm is quite straightforward and is recommended for wider application. [ABSTRACT FROM AUTHOR]

Large squeezing deformation has always been a critical concern in the construction of deep-buried tunnels in soft-weak rock masses. This paper describes a case study on the large deformation mechanism and supporting method of the Maoxian tunnel in Sichuan Province, China, which is located in the core area influenced by the 2008 Wenchuan earthquake and suffered severe large deformation in broken phyllite under high geo-stress. Through a survey on the geological features, the deformation mechanism of surrounding rock and the failure characteristics of supporting structures of the Maoxian tunnel in F1 fault zone were studied. It was found that the occurrence of large deformation was due to the combined action of the high geo-stress and poor self-stability of carbonaceous phyllite. In order to control the squeezing deformation, single and double primary support methods were adopted in succession. A comparative field test was conducted to study their supporting mechanism and mechanical behavior in terms of surrounding rock pressure, internal stress of the steel arch, and axial force and bending moment of the secondary lining. The results revealed that the single primary support method cannot ensure the long-term safety of the tunnel, since many cracks in concrete occurred after about 180 days. The double primary support method, however, was able to control the large deformation and rheological effects of broken phyllite under high geo-stress effectively. [ABSTRACT FROM AUTHOR]

For the subsea reinforced concrete (RC) shield tunnels in China, the use of super large tunnel section and the presence of high hydrostatic pressure from seawater have been becoming increasingly common in practical engineering. However, owing to the combined effects of complex structural systems, extreme external loads and aggressive environments, it is a great challenge to sustain a reliable structural performance of these subsea shield tunnels within the prescribed service life. In this study, a novel approach for evaluating the structural safety of a deteriorated large-section subsea RC shield tunnel is presented with an emphasis on the spatial correlation and variation of corrosion damages and the impact of high hydrostatic pressure. Gumbel distributed random fields are established to simulate the spatial variability of steel corrosion in the segmental linings. A random field-based numerical model for the deteriorated RC segmental linings is developed in conjunction with the modeling of nonuniform steel corrosion and local-regional material degradation. In an illustrative example, the effects of the corrosion degree of internal and external steel reinforcements and the level of applied hydrostatic pressure on the structural safety of a large-section subsea RC shield tunnel are investigated. • Random field-based modeling for nonuniform steel corrosion is introduced. • Deteriorated performance of shield tunnels with a super large cross-section is revealed. • Bending moment is much sensitive to the change of corrosion state in segment. • Steel corrosion in tunnel extrados can cause a greater deterioration deformation. • High hydrostatic pressure exacerbates the serviceability and safety of degraded tunnels. [ABSTRACT FROM AUTHOR]

The stability of landslides in reservoir areas is significantly influenced by water level fluctuations and seasonal precipitation events. To mitigate these landslides, a pile-anchor (PA) structure has been developed by adding anchors to common anti-slide piles. However, limited research has been conducted on the behaviours of PA reinforced reservoir landslides under changing environmental conditions. In this study, model tests of PA reinforced landslide were carried out using a multi-field monitoring technique to investigate the behaviours of PA reinforced landslides. The study utilized the Majiagou landslide in the Three Gorges Reservoir region of China as a prototype. Three sets of model tests were conducted to simulate the three different triggers of varying water level, rainfall, and thrust load experienced by landslides in reservoir areas. Furthermore, the performance of PA structures was compared to that of pile structures to demonstrate the superiority of the PA structure reinforced landslide. The results indicated that the behaviours of PA remain consistent regardless of the three different triggers, and their general performance can be divided into three stages: stable, fast-deformed, and slow-deformed stage. The distribution of the bending moment exhibits an S-shaped curve, with the maximum bending moment near the slip surface. The maximum negative shear force in the bedrock indicates that part of the structure embedded in the bedrock can effectively resist sliding thrust. In addition, the softening effect can lead to the different responses of PA reinforced landslides under different triggers. This study may provide a deeper understanding of the behaviors of the PA reinforced landslides in response to evolving environmental conditions in reservoir areas. • Tests of pile-anchor (PA) reinforced slope are conducted through multi-field monitoring • Triggers of varying water level, rainfall and thrust load are considered in the tests. • Behaviour of PA can be divided into stable, fast-deformed and slow-deformed stages. • PA presents S-shape distribution of bending moment and lower displacement ratios. • The softening effect leads to the different responses of PA reinforced landslide. [ABSTRACT FROM AUTHOR]