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Copyright of Guangdong Architecture Civil Engineering is the property of Guangdong Architecture Civil Engineering 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.)

Copyright of Urban Geology is the property of Urban Geology 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.)

Copyright of Fly Ash Comprehensive Utilization is the property of Hebei Fly Ash Comprehensive Utilization Magazine Co., Ltd. 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.)

AbstractIn this study, combined empirical, numerical, and in-situ monitoring methods were combined to carry out stability analyses and support design for a haulage drift subjected to mining activity. The rock mass quality of the haulage drift was characterized by the RMR, Q, and GSI, and the rock mass properties were calculated. The support requirements for haulage drift during mining were determined by rock mass classification systems. RS2 was used to analyze the plastic zone and displacement of the haulage drift during mining. After the stope was mined, the surrounding rock exhibited a butterfly plastic zone with an asymmetric distribution, and the roof damage was most severe near the stope side. Overall, the haulage drift tended to move in the stope direction, which is consistent with engineering expectations. The support systems determined using the empirical method were analyzed using RS2 and UNWEDGE software. The maximum plastic zone depth of the roof decreased from 4.2 to 2.01 m, and the safety factor of the unstable wedge block increased from 0 to 10.2 after support. In-situ drilling detection shows that the failure depth of the haulage drift roof is 2.37 m. Therefore, a combination of empirical, numerical, and in-situ monitoring methods can be effective for quantitative stability assessments and support design optimization of haulage drifts in the vicinity of mined stopes.

During the construction of a diversion tunnel, geological problems often include faults, fragile strata, hard rock formations, karst landforms, etc., which may have adverse effects on the excavation and construction of the diversion tunnel. Based on the analysis of the engineering overview, this study designed a new construction technology for the excavation of water diversion tunnels in hard rock layers and high-karst areas. Based on tunnel seismic prediction (TSP) technology to achieve advanced geological prediction, combined with actual geological conditions, construction difficulties are analyzed. Then, detection technology is used to collect two-way travel time, amplitude, and waveform data. By processing and analyzing the detection image, the spatial orientation and length of the main tunnel during the construction of the diversion tunnel are calculated. After completing the construction ventilation and wind, water, and electricity layout, the excavation construction procedure is designed. In the specific excavation design, the tunnel curtain excavation technology, tunnel body excavation and support technology, excavation grouting technology, important unfavorable geological tunnel section excavation technology, upper/lower flat section excavation technology, upper/lower curved section excavation technology, and vertical shaft section excavation technology were elaborated. Finally, a plan was made for the reuse process of slag material and a construction quality control system was established. During the testing process, it was found that the antidamage coefficient of the side wall was above 0.9 after using the technology described in this article. Therefore, it indicates that the excavation construction technology designed in this article can ensure the support capacity of the side wall of the diversion tunnel, which is suitable for the excavation of the main tunnel during the construction of the diversion tunnel. [ABSTRACT FROM AUTHOR]

Copyright of Tunnel Construction / Suidao Jianshe (Zhong-Yingwen Ban) is the property of Tunnel Construction 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.)

Coal resources have always been the focus of attention in the field of sustainable development. Based on the problem of surrounding rock control in close-distance coal seams, first, a mechanical model of floor failure was established based on the 29204 working face in Dongqu Mine; the failure mechanism of the floor was revealed by the zero displacement line, and a method to judge the occurrence state of the roof in the lower coal seam was put forward. Furthermore, by FLAC3D numerical simulation software, the mechanical model is verified, and the optimal support parameters are optimized, and the optimal water–cement ratio and grouting pressure are determined to be 0.6 and 3 MPa respectively. The application shows that the roof displacement is reduced by about 73.48% compared with the control group. Compared with the control group, the cable stress decreased by about 50.68%, and the application effect is remarkable. The research results provide an effective solution to ensure the sustainable development of coal resources and disaster prevention. [ABSTRACT FROM AUTHOR]

The transportation of oil and gas in Russia's northern and Arctic regions has seen significant growth in recent years. However, the presence of permafrost in these areas can cause malfunctions in the main pipelines due to soil frost heaving. The operational pipelines also often suffer from various defects in their body and surface. To mitigate these issues, above-ground trunkline supports are utilized to protect the pipelines from cryogenic processes. Nevertheless, these supports are subjected to ground loads caused by cryogenic frost heaving, which poses a threat to the pipeline's integrity and the environment. In response to these challenges, this study presents a design for pipeline support to maintain the pipeline's stability in the face of soil displacement caused by unequal frost-heaving forces. A numerical model was created to evaluate the fracture of frozen rock and the resulting stresses in the soil and support structure. The input data for the model includes coefficients that describe the soil's state during the cryogenic process and the proposed support's parameters. The experimental results showed the proposed design to be effective in protecting the pipeline from soil frost heaving. The paper also provides the results of numerical and experimental studies on soil fracture stresses depending on the rock type and temperature. This design promises to increase both the safety of above-ground trunk pipelines and their technological efficiency. [ABSTRACT FROM AUTHOR]

In Selective Laser Melting, the design of efficient support structures is the key to enable the production of high-quality functional parts exhibiting complex shapes with improved geometrical accuracy. Nonetheless, from a process point of view, supports are waste material that must be minimized to reduce production costs and post-processing. Despite the recent technological advances, support optimization is based on time- and resource-consuming trial-and-error experimental campaigns, while support removal is primarily a manual operation which requires a consistent human effort and consumable consumption. Nowadays, the industry is demanding a tool capable to optimize support design and placement based on part geometry and building orientation, by ensuring high part geometrical accuracy along with reduced timing for post-processing operations. Specifically, the purpose of this experimental campaign, is to evaluate the influence of support thickness and tooth length on the dimensional accuracy of AISI 316 l cantilever specimens in order to form a solid baseline of knowledge for the future realization of an automated algorithm for optimized support structure generation based on both part and process requirements. The experimental results show that the support thickness strongly affects the final part distortion, reducing the as-built geometrical deviation by 72.6% when wall thickness increases up to 0.7 mm, whereas tooth length has a higher impact on post-processing when decreased from 0.7 mm to 0.3 mm, reducing support time removal and consumables usage respectively up to 40.5% and 72.7%. The achieved results highlight that the implementation of optimized support structures ensuring low geometrical deviation and involving reduced resource consumption in post-processing is feasible. These findings provide the starting design rules for the engineering of an empirical methodology, based on thermomechanical modelling, enabling optimized design and implementation of SLM support structures.

Aiming at the problems of severe ground pressure behavior during final mining and poor roof maintenance effect in B10 coal face of Shajihai Coal Mine, a systematic study was carried out by means of field measurement, numerical simulation and theoretical analysis. The roof structure and crack development of the withdrawal channel were mastered through the roof drilling peep. The FLAC3D numerical model of withdrawal channel was established, and the stress distribution and plastic zone evolution law of surrounding rock in withdrawal space were compared and analyzed under the two schemes of pre-excavation single withdrawal channel and self-excavation withdrawal channel. The roof hierarchical control principle of large fracture depth in withdrawal space was proposed, and a roof hierarchical control method dominated by medium and long anchor cables was formed. Based on this, the roof support scheme design of withdrawal channel in B1003W03 working face and the surface displacement monitoring of surrounding rock were carried out. The results show that compared with the layout of pre-excavation single withdrawal channel, the supporting stress distribution and plastic failure range of surrounding rock in the withdrawal space under the form of self-excavation withdrawal channel have been improved. The design of support scheme can effectively control the roof of shallow-middle-deep layer. The monitoring data show that the withdrawal channel deformation is small and the support effect is good.

Considering the harsh environment of deep, fully mechanized working faces and the acutely imbalanced time distribution among excavation, support and anchoring, this paper designed a new type of highly adaptable advance support for fully mechanized roadways that boasts high adaptability, great support strength and a large working space. Firstly, the structure composition and working principle of the advance support were introduced. The structures and mechanical characteristics were then emphatically discussed. Subsequently, with the geological conditions of the 8224-machine roadway in the XT Coal Mine taken as an example, the loads of the advance support were obtained and then imported into the Ansys software to obtain the stress distribution and displacement distribution of the whole advance support and its parts through calculation. Based on the distribution, the stress and strain of the advance support were analyzed. The simulation results are as follows: Under various working conditions, the maximum displacement of the advance support was 4.5 mm, which is negligible compared to the overall size of the support; the maximum stress was 72.8 MPa, which is lower than the yield strength of the material (235 MPa). Therefore, the designed support can bear the pressure from the surrounding rock in the mine. Moreover, the roof beam, which is a weak link in the support, deserves more attention in subsequent engineering designs. This method conduces to not only parallel operations of excavation, support and anchoring, but also to rapid excavation and the safe production of roadways, providing fresh ideas for the advance support for fully mechanized roadways. [ABSTRACT FROM AUTHOR]

Large deformation and support failure of a tunnel with poor lithology, which significantly threaten the stability of the tunnel, have always been major difficulties in underground engineering construction. This paper describes a case study of the failure mechanisms and support design for tailrace tunnels that cross a wide fracture zone in the Wuyue pumped storage power station in Henan Province, China. Geological investigation and mechanical experiments, including large-scale triaxial tests, X-ray diffraction, and free swell tests, were performed to reveal the failure mechanism of the tailrace tunnel. It was observed that the surrounding rock of the tunnel is a completely weathered granite that is characterized by extremely poor rock mass quality, severe deformation, and significant expansibility. Based on the failure mechanism and combined with the concept of “inner and outer load-bearing structures”, a multilevel support system with “long anchor bolts + anchor bolts + rigid arch” as a core is proposed with consideration of the rotation of the principal stress axis. Numerical simulation was adopted to verify the rationality of the proposed support system compared with other support conditions, i.e. no support and uniform support. The results indicate that the proposed support system effectively improves the principal stress state of a tunnel with poor lithology and controls the large deformation of the surrounding rock, especially in the floor and inclined sidewall. Additionally, three successful application cases were introduced to promote the utilization of the proposed support, and possible improvements in enhancing engineering applications were evaluated. The support methodology presented in this paper can support the design of other engineering projects in complex geological environments. [ABSTRACT FROM AUTHOR]

Serious games are considered an effective method to engage students in programming education and have been increasingly used in classrooms. An important part of the learning process with serious games involves the presentation of the new concepts and the provided support to encounter student difficulties. Although the most common approach is the use of instructional text, it comes with some drawbacks. This paper proposes an alternative method for user support in serious games about programming which mitigates current problems and provides improved learning efficiency. An experiment was conducted (N = 291) to test textual instructions learning efficiency compared to in-game worked examples. Two randomly assigned groups used different types of support in a block-based game, developed for the study. Our implementation provided support through a non-player character who executed worked examples inside the game world. The analysis showed a significant statistical difference in score performance between the two supports on both novice and experienced students. The results point to increased learning efficiency by students, when in-game worked examples and problem-solving are combined. We further argue that the Cognitive load theory can provide adequate justification for the outcomes. [ABSTRACT FROM AUTHOR]

Convergence-confinement method (CCM) has become a common method for tunnel design due to its simplicity and practicality. The ground reaction curve (GRC), the support characteristic curve (SCC) and the longitudinal deformation profile (LDP) are all considered in this method. One of these is the LDP which serves as a unique identifier for the location of the tunnel support. The installation point of the tunnel support is one of the most important outcomes of the method. LDP is more impacted by the reinforcement of the tunnel face. However, more existing LDP calculation methods do not consider the reinforcement of the tunnel face. A study on methods for calculating LDP considering the tunnel face reinforcement was carried out to address this constraint of CCM. Firstly, the transformation of tunnel face extrusion deformation and pre-convergence deformation at the tunnel face is realized in accordance with equivalent volume. Then a model of LDP with the tunnel face extrusion deformation as the variable was established considering the tunnel face reinforcement effect. The proposed model's accuracy is assessed in comparison with other typical models. We conclude with parametric analyses concerning the tunnel face reinforcement's effects on the point of support installation, as well as convergence deformation of the tunnel. By taking into account tunnel faces' reinforcement effects, tunnel support design can be more accurate, and the construction costs can be reduced. [ABSTRACT FROM AUTHOR]

During the construction of a diversion tunnel, geological problems often include faults, fragile strata, hard rock formations, karst landforms, etc., which may have adverse effects on the excavation and construction of the diversion tunnel. Based on the analysis of the engineering overview, this study designed a new construction technology for the excavation of water diversion tunnels in hard rock layers and high-karst areas. Based on tunnel seismic prediction (TSP) technology to achieve advanced geological prediction, combined with actual geological conditions, construction difficulties are analyzed. Then, detection technology is used to collect two-way travel time, amplitude, and waveform data. By processing and analyzing the detection image, the spatial orientation and length of the main tunnel during the construction of the diversion tunnel are calculated. After completing the construction ventilation and wind, water, and electricity layout, the excavation construction procedure is designed. In the specific excavation design, the tunnel curtain excavation technology, tunnel body excavation and support technology, excavation grouting technology, important unfavorable geological tunnel section excavation technology, upper/lower flat section excavation technology, upper/lower curved section excavation technology, and vertical shaft section excavation technology were elaborated. Finally, a plan was made for the reuse process of slag material and a construction quality control system was established. During the testing process, it was found that the antidamage coefficient of the side wall was above 0.9 after using the technology described in this article. Therefore, it indicates that the excavation construction technology designed in this article can ensure the support capacity of the side wall of the diversion tunnel, which is suitable for the excavation of the main tunnel during the construction of the diversion tunnel.

Storage ponds (storm detention ponds) are an important part of sponge city construction, and the construction process involves deep and large pit excavation in a complex and sensitive environment. Combined with a large storage pond pit engineering design and practice process, in this study, the complex environment of the design of the large storage pond pit method has been explored, using the field measurement data to test the support design of the deformation control effect and to summarize the practice of the key, difficult points of treatment measures. The results show that the procedure adopted in this project is a successful practice for using the pit characteristics, and the special treatment carried out for addressing the difficult points can effectively control the deformation, thus achieving waterproofing and deformation requirements of large-capacity water storage ponds. The design of the support is very effective in controlling the duration and deformation. The cover-cut excavation method, in combination with the support system, is highly effective in deformation control, whereas the open-cut excavation method is more likely to shorten the duration. However, there is an uncertainty in the deformation control during the removal of temporary structures in this method. The deformation characteristics of the pit enclosure and the surrounding ground surface are within the design requirements. The horizontal displacement of the wall and the surrounding settlement are mainly developed during the stage of dismantling the temporary support structure after excavating the first basement level and during the construction of the first and second slabs. The other stages benefit from the strong integrity of the support system, which can efficiently control the deformation. The treatment measures, support types, and component connection methods summarized in this article can provide a reference for the construction of similar underground storage ponds. [ABSTRACT FROM AUTHOR]

As per most other earth science engineering problems, the underground coal geotechnical environment and the way in which roof and rib support interacts with the rock mass are complex issues. It is therefore generally recognised that without prudent simplification, the complexity of the problem will overwhelm all current geotechnical methods of modelling, not least for the reason that a rock mass can never be characterised to a level that allows a “non-simplified” analysis. The fact that numerical models, which are commonly purported to be a “simulation” tool and the so-called epitome of advanced geotechnical engineering, always need to be “calibrated” to a known reality is taken to be conclusive proof of this statement. While the problem should not be oversimplified (i.e. the dominant failure mechanisms or critical data input parameters should not be ignored), without question judicious simplification is at the heart of all engineering design, to the point that it has a well-established name – “reductionism”. The hypothesis addressed in this paper, is that horizontal and vertical stress-driven slender beam and column behaviour (which includes unstable Euler Buckling) are respectively the dominant (but not only) roadway roof and ribline behavioural mechanism that (if not controlled) can lead to excessive deformation, failure and eventual collapse. As a part of the Scientific Method, a hypothesis can only be tested via real-world observations, measurements and analyses in establishing it is a credible Theory. Utilising the Scientific Method, this paper demonstrates that slender beam/column behaviour is the dominant instability mechanism within a coal mine roof/rib subject to elevated horizontal/vertical stress conditions and therefore, must be representatively accounted for in any credible empirical, analytical, or numerical approach to coal mine roof/rib stability assessment and associated ground support design.

Copyright of Nonferrous Metals (Mining Section) is the property of Beijing Research Institute of Mining & Metallurgy Technology Group 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.)

Longwall gateroad entries are subject to changing horizontal and vertical stress induced by redistribution of loads around the extracted panel. The stress changes can result in significant deformation of the entries that may include roof sag, rib dilation, and floor heave. Mine operators install different types of supports to control the ground response and maintain safe access and ventilation of the longwall face. This paper describes recent research aimed at quantifying the effect of longwall-induced stress changes on ground stability and using the information to assess support alternatives. The research included monitoring of ground and support interaction at several operating longwall mines in the U.S., analysis and calibration of numerical models that adequately represent the bedded rock mass, and observation of the support systems and their response to changes in stress. The models were then used to investigate the impact of geology and stress conditions on ground deformation and support response for various depths of cover and geologic scenarios. The research results were summarized in two regression equations that can be used to estimate the likely roof deformation and height of roof yield due to longwall-induced stress changes. This information is then used to assess the ability of support systems to maintain the stability of the roof. The application of the method is demonstrated with a retrospective analysis of the support performance at an operating longwall mine that experienced a headgate roof fall. The method is shown to produce realistic estimates of gateroad entry stability and support performance, allowing alternative support systems to be assessed during the design and planning stage of longwall operations.

Aiming at the problems of roadway deformation and support difficulty under the influence of lateral mining, taking 22304 return air roadway of Bulianta Coal Mine as the research background, through theoretical analysis and numerical simulation method, the distribution law of surrounding rock stress is obtained, and the relationship among different positions of surrounding rock, main stress difference and plastic area is analyzed from multi-dimensional perspective, and the failure mechanism of surrounding rock is obtained, and the control effect of surrounding rock reinforcement is further analyzed. The results show that the stress distribution of the surrounding rock in the side entry of the goaf shows a certain regularity in space, the main stress changes a lot in the rear of the working face, and the main stress difference is stable about 300 m behind the coal wall; the main stress difference has a positive correlation with the size of the plastic area; the main stress size and direction change of the surrounding rock behind the working face lead to the asymmetric distribution characteristics of the plastic area; then, the key parts of the reinforcement support are determined. Through analysis, the reinforcement scheme is highly targeted and can achieve the purpose of synergistic control of the two sides and the roof to ensure the stability of surrounding rocks.

High slope stability control is a crucial technical issue in water conservancy and hydropower project construction. This issue is relevant throughout the entire engineering-related survey, design, construction, and operation process. This paper reports a recent case in which significant deep-seated deformation occurred during slope excavation. Several unfavorable structural surfaces were revealed throughout the slope’s undercutting process, particularly fault fz39, which ran diagonally through the entire slope from top to bottom. On the slope surface, damage such as cracking, bulging, and local slippage appeared. The measured value of multipoint displacement meters increased in a stepwise pattern with each blast, and the maximum measured value exceeded 100 mm. The studied slope’s whole excavation and reinforcement process is described in detail. We analyzed the deformation mechanism of the excavation slope by combining the geological conditions, real-time safety monitoring findings, and site deformation characteristics. The slope reinforcement scheme was optimized based on the preceding analyses. We used a three-dimensional numerical calculation program to simulate the slope excavation and unloading process to reproduce the current mechanical state of the slope, evaluate the reinforcement measures, and provide a useful reference for decision making. The analysis shows that the deformation behavior of the studied slope is closely related to fault fz39 and fracture L920, and presents a typical wedge failure mode. The deep-seated deformation of the excavation slope occurs at the junction of the wedge and bedrock, which is mainly affected by unfavorable geological structure surfaces, excavation unloading, and blasting vibration. The reinforcement scheme of unloading at the top of the slope and large-tonnage cables are established. The numerical analysis results showed that the design of the slope reinforcement measures was appropriate and ensured slope stability. The work described in this paper deepens our understanding of the occurrence of large deep-seated deformation on the structural-controlled slope under the action of excavation and improves the design philosophy.

Copyright of Tunnel Construction / Suidao Jianshe (Zhong-Yingwen Ban) is the property of Tunnel Construction 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.)

To solve the problems of large deformation and supporting difficulties in soft rock roadway in strongly weathering zone, and taking the soft rock roadway along the wind oxidation zone edge of No. 7 coal seam in a mine as the engineering background, the causes of deformation and instability of roadway surrounding rock are summarized according to the characteristics of deformation and failure. Based on the above analysis, we propose the design scheme of strengthening support with the shed for the excavated roadway, and design the roadway section as rectangle for the non-excavated roadways, and adopt the combined support mode of bolt-mesh as the basic support in roadway + strengthening support with the shed + shotcrete. The industrial test shows that the optimized support scheme can effectively control the deformation of surrounding rock and maintain the roadway long-term stability, which effectively solves the problem of large deformation and difficult support in strongly weathering zone.

The transportation of oil and gas in Russia’s northern and Arctic regions has seen significant growth in recent years. However, the presence of permafrost in these areas can cause malfunctions in the main pipelines due to soil frost heaving. The operational pipelines also often suffer from various defects in their body and surface. To mitigate these issues, above-ground trunkline supports are utilized to protect the pipelines from cryogenic processes. Nevertheless, these supports are subjected to ground loads caused by cryogenic frost heaving, which poses a threat to the pipeline’s integrity and the environment. In response to these challenges, this study presents a design for pipeline support to maintain the pipeline’s stability in the face of soil displacement caused by unequal frost-heaving forces. A numerical model was created to evaluate the fracture of frozen rock and the resulting stresses in the soil and support structure. The input data for the model includes coefficients that describe the soil’s state during the cryogenic process and the proposed support’s parameters. The experimental results showed the proposed design to be effective in protecting the pipeline from soil frost heaving. The paper also provides the results of numerical and experimental studies on soil fracture stresses depending on the rock type and temperature. This design promises to increase both the safety of above-ground trunk pipelines and their technological efficiency.

Considering the harsh environment of deep, fully mechanized working faces and the acutely imbalanced time distribution among excavation, support and anchoring, this paper designed a new type of highly adaptable advance support for fully mechanized roadways that boasts high adaptability, great support strength and a large working space. Firstly, the structure composition and working principle of the advance support were introduced. The structures and mechanical characteristics were then emphatically discussed. Subsequently, with the geological conditions of the 8224-machine roadway in the XT Coal Mine taken as an example, the loads of the advance support were obtained and then imported into the Ansys software to obtain the stress distribution and displacement distribution of the whole advance support and its parts through calculation. Based on the distribution, the stress and strain of the advance support were analyzed. The simulation results are as follows: Under various working conditions, the maximum displacement of the advance support was 4.5 mm, which is negligible compared to the overall size of the support; the maximum stress was 72.8 MPa, which is lower than the yield strength of the material (235 MPa). Therefore, the designed support can bear the pressure from the surrounding rock in the mine. Moreover, the roof beam, which is a weak link in the support, deserves more attention in subsequent engineering designs. This method conduces to not only parallel operations of excavation, support and anchoring, but also to rapid excavation and the safe production of roadways, providing fresh ideas for the advance support for fully mechanized roadways.

The excellent thermal and chemical stability of monolayer graphene makes it an ideal material for separations at high temperatures and in harsh organic solvents. Here, based on understanding of solvent permeation through nanoporous graphene via molecular dynamics simulation, a resistance model was established to guide the design of a defect-tolerant graphene composite membrane consisting of monolayer graphene on a porous supporting substrate. Guided by the model, we experimentally engineered polyimide (PI) supporting substrates with appropriate pore size, permeance, and excellent solvent resistance and investigated transport across the resulting graphene-covered membranes. The cross-linked PI substrate could effectively mitigate the impacts of leakage through defects across graphene to allow selective transport without defect sealing. The graphene-covered membrane showed pure solvent permeance of 24.1 L m-2 h-1 bar-1 and stable rejection (~90%) of Allura Red AC (496.42 g mol-1) in a harsh polar solvent, dimethylformamide (DMF), at 100 °C for 10 d. [ABSTRACT FROM AUTHOR]

To overcome the problems existing in the application of the traditional stability control method of the surrounding rock of deep shafts, in this paper, a stability control method for the surrounding rock of deep shafts is presented based on the New Austrian Tunnelling Method (NATM) and the Norwegian Method of Tunnelling (NMT), and a support design method of deep shafts is also proposed. In addition, taking a deep shaft construction project as an example, the support design process of a deep shaft is presented: the engineering geology and in situ stress of the deep shaft are collected and processed to evaluate the rock mass quality with the Q-system, rock mass rating (RMR), and geological strength index (GSI). The strength and deformation parameters of the intact rock are obtained via laboratory tests, and the rock mass mechanical parameters are calculated using the generalized Hoek–Brown method. Then, a variety of support design methods based on rock mass classification systems are applied to determine the primary and permanent support, and the support time is obtained on the basis of a convergence-confinement analysis and engineering experience. A two-dimensional plane-strain model is constructed to analyze and evaluate the safety of the proposed support system, incorporating the major geological discontinuities and non-hydrostatic in situ stress state prior to excavation. [ABSTRACT FROM AUTHOR]

Rock-support interaction is one of the most core issues in underground engineering, which is of major interest to supporting structure design, construction safety and cost, as well as environmental protection. In order to study the rock-support interaction in deep tunnel under complex geological conditions, taking Xianglushan Tunnel of Yunnan Water Diversion Project in China as the engineering background, two true three-dimensional physical model tests were conducted. The model test results show: (1) the surrounding rock and support are a pair of opposite and united contradictions, which are both antagonistic and cooperative; (2) the rock-lining interaction and rock-bolt interaction are distinctly different. The lining is a type of outside supporting structure to bear the load from surrounding rock and the bolt is a kind of inside supporting structure to reinforce and protect surrounding rock; (3) the impacts of weak fault on mechanical behavior of surrounding rock and supporting structure are significant. The load bearing effects of surrounding rock and support system exhibit different characteristic depending on the corresponding geological conditions. The results can contribute to the development of construction scheme and optimization of support design, and also provide an ideal data set for the calibration and validation of numerical models to simulate the rock-support interaction. [ABSTRACT FROM AUTHOR]

The roadways with top coal are a common type of roadways in thick coal seam mining. After excavation of such roadways, the top-coal rock mass is often loose and broken, and the roof deformation and failure are serious. Thus, the stability control of such roadways is a major concern of engineering design and construction personnel. In this paper, we take the typical roadways with top coal in Zhaolou coal mine of China's Juye mining area as an example and propose a composite failure mechanism for roadway roof supported by rock bolting. The roof stratification and nonlinear failure characteristics of rock masses are incorporated in it. Then, a simplified design method of roof bolting support is proposed on the basis of the upper bound theorem. Furthermore, this paper shows the influence laws of varying parameters on the required supporting force of roof bolts and provides several practical recommendations for engineering applications. In addition, the effectiveness of the proposed method in this paper is further verified through a specific case analysis on a site typical roadway. The research work in this paper can provide theoretical guidance for support design and construction in roadways with top coal. [ABSTRACT FROM AUTHOR]

Ground control is multi-tasking and continuous process for the stability of underground openings. Balya underground lead and zinc mine is an important case study area due to its deepest working condition and the highest production amount among Turkish underground metalliferous mines. Mining-induced seismicity needs to be investigated especially for deep as well as tectonically active mine sites. Increasing depth will increase the stress around an underground opening that is a key factor of rock-burst hazard. Rock burst potential can be estimated from analytical approaches based on the relation between rock mass strength and stress around openings; however, one of the best way is to monitor the mining-induced seismicity. The support system is designed based on the actual geotechnical conditions determined from the excavated working face prior to support applications in the mine. Empirical methods are then used to make a decision about the support system. If the location is designated as a seismically active region based on micro-seismic event results, support components are selected as a dynamic support system that must absorb the energy released from the surrounding rock masses. The purpose of this study is to investigate seismically active locations according to mining-induced seismicity and the support system design principles for that locations to protect the openings against seismic loads. [ABSTRACT FROM AUTHOR]

The Muzhailing extra-long highway tunnel and corresponding inclined shafts in Lanzhou, Gansu Province, China passes through structurally complex carbonaceous slate that is under high ground stress. Rationally-designed and effective support is of high importance for achieving safe and efficient tunnel construction. The No. 2 inclined shaft of Muzhailing Tunnel was taken as the engineering background prototype, for which, a similar model test was conducted to evaluate the effect of highly pre-tightened constant resistance (NPR, Negative Poisson's Ratio) anchor cable support provision to the geologically complex carbonaceous slate at different depths. Two schemes were proposed during testing: one scheme was without support and the second was with asymmetric support from highly pre-tightened constant resistance anchor cable. Digital speckle displacement analysis system and micro-ground-stress sensors were employed to measure the deformation and shear stress distribution of the tunnel. The results demonstrated that through the second support scheme, the deformation of the surrounding rock could be effectively ameliorated, while this support scheme was applied on the project site of the No.2 inclined shaft, to explore the rationality of the scheme through field engineering tests. On-site monitoring indicated that the deformation of the surrounding rock was within the reasonable design range and the problem of severe tunnel deformation was effectively controlled. The research methods and related conclusions can be used as a reference for the treatment of large deformation problems in deep-buried soft rock tunnels. [ABSTRACT FROM AUTHOR]

In this work, the sup port of two general galleries located in poor quality rock mass and subjected to the influence of high thickness coal layer exploitations is designed and optimized. The process is carried out in four phases: A first preliminary support is defined employing different geomechanical classifications and applying the New Austrian Tunnelling Method (NATM) using bolts and shotcrete. An instrumentation campaign is carried out with the goal of analysing the behaviour of the support. The study noticed the failure of the support due to the time of placement of the different elements. A back-analysis using the Flac and Phases software has allowed the evaluation of the properties of the rock mass and the support, the study of the influence of the time of placement on the component elements (bolts and shotcrete), and the redefinition of that support. Subsequently, a new support is designed and optimized through numerical modeling after the start of mining without experience in these sizes of sublevel caving that caused the failure of the previously designed support. The new support is formed by yieldable steel arches that are more suitable to withstand the stresses generated by nearby mining work. [ABSTRACT FROM AUTHOR]

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The purpose of this study is to investigate the slope stability problem that occurred in the Ulubey (NE Turkey) during the construction of a hospital building and to propose a reliable support design. The borehole applications, geophysical surveys, groundwater measurements, soil sampling and SPT were performed to establish the geotechnical model. Based on the site characterization investigations, three units were defined as sliding material, residual regolith and volcanic rocks. Strength parameters of the sliding and residual soil materials were obtained from the back analysis. The long-term performance of the double row-bore piles was proposed as support measures and was controlled using the limit equilibrium (LE) and finite element (FEM) analyses methods under a dynamic condition. The 2D-LE and 2D-FEM analysis results showed that the suggested support design is reliable for long-term stability. The locations of the critical shear surface determined by 2D methods were almost the same as those obtained from 3D-FEM method and the total displacement values obtained from the 3D-FEM model were smaller than those obtained from the 2D-FEM model. These results indicated that 2D and 3D stability analyses were sufficient to evaluate the stability of uncomplex slope geometry when a reliable design with simple solutions was required. [ABSTRACT FROM AUTHOR]

The Wudongde Hydropower Station is constructed in layered strata that typically have steep dip angles. These features, together with the folds and faults that have developed in the strata, directly threaten the stability of the underground powerhouse. In this work, the behavior of the surrounding rocks under the original support measures is detailed in terms of rock mass deformation, anchor bolt stress, and extent of the excavation-disturbed zone, as obtained from safety monitoring and field testing. The characteristics of deformation and cracking of the surrounding rocks were also interpreted. To enhance rock mass stability, the support design and construction process were optimized and the positions liable to cracking treated. The efficiency of suggested scheme is verified by subsequent safety monitoring data and field testing. Then, a transversely-isotropic elastoplastic constitutive model for the layered rock masses was established. Numerical simulations are performed during the construction process to provide reference for decision making. The calculated deformations are in good agreement with the monitored values and they tended to be more stable. The plastic zones of the surrounding rocks fall within the range controllable using cables. Thus, the proposed measures are necessary and ensure sufficient stability. Finally, the mechanisms for the deformation and cracking of the surrounding rocks during the construction process are discussed. The work described aims to deepen our understanding of the mechanical properties of layered rock masses with steep dip angles and to improve the design philosophy. [ABSTRACT FROM AUTHOR]

At present, there is no unified support design criterion for the construction of super-large cross-section tunnel. The design of initial supporting components is based on engineering analogy method, lacking theoretical and experimental guidance. The spacing of arch and longitudinal connection strength have significant influence on the bearing capacity of initial support system, so in-depth study in this area is very important. Therefore, based on the typical super-large cross-section tunnel-Letuan Tunnel of Binlai Expressway in China, laboratory test and numerical test are carried out in this paper to study the combinational bearing mechanism of multiple spatial arches in initial supporting system. This paper also clarifies the mechanical characteristics of spatial supporting system and the influence mechanism different designing parameters such as arch spacing, longitudinal connection spacing. The cost performance of each design scheme of the spatial supporting arch system is established. The research results show that the influence of arch spacing and longitudinal connection spacing on arch bearing capacity is remarkable. Strength of combined arch structures is 3.14–3.92 times of single arch frame. The influence of arch spacing is more obvious than that of longitudinal connection spacing. The research results can provide reference for related projects. [ABSTRACT FROM AUTHOR]

The stability of the entries of longwall panels is a major concern in underground coal mines. While panel entries have a short service life, they must be well supported to sustain the mining-induced loads during panel extraction. In this paper, a panel-wide numerical model was built with FLAC3D to examine a longwall panel entry with poor stability. The processes of entry development and panel retreat mining are simulated with three different entry support designs: the original design in the field and two newly proposed designs. The ground stability in each support condition was examined and compared in terms of ground deformation and extent of failure. A field test was then conducted to compare the three support designs. An instrumentation program was put in place in the field, and monitoring results were used to validate the numerical models. An optimal support design under the associated geological and geotechnical conditions was obtained. The underlying support mechanism was further analyzed with numerical modeling in the view of support-induced stress distribution in the surrounding rock mass. The results suggest that employing proper support with pre-tension generates a large area of support-induced stress in the surrounding rock mass, thereby improving the ground stability in terms of eliminating rock failure and limiting deformation. The results of this study contribute to the understanding of the role of pre-tensioned supports and can be utilized for support design and optimization under similar geological and geotechnical circumstances. [ABSTRACT FROM AUTHOR]

This work study the auxiliary shaft in Jinchuan No. 3 mining area. A numerical calculation method is adopted in this study to optimize retention space to yield for the support of the shaft and to analyze the stability of the surrounding rock mass to solve the large deformation problem occurring in shaft excavation. Firstly, three different sections are investigated, including the shaft wellhead section, main body and cross-cut under the shaft. Support and reinforcement solutions based on the retention space to yield support technology of shaft are proposed twice to resolve the corresponding problems appearing during construction. The relationship between the thickness of the lining and the convergence of the lining, the thickness of the plastic zone and the maximum principal stress of the lining is then identified through a planar model analysis on the shaft cross-section with the depth of 250 m, 400 m, 500 m, and 650 m. Lastly, a three-dimensional numerical simulation and safety evaluation of the first support design (50 mm bolt–shotcrete mesh + 450 mm plain concrete), as well as a stability analysis on the adjusted support solution (50 mm bolt–shotcrete mesh + 750 mm plain concrete) for a stratum of poor conditions are carried out using software FLAC3D. [ABSTRACT FROM AUTHOR]

Physical adsorption by mesoporous silica support has been widely used as a stabilization strategy of enzymes. The characteristics of support influence loading amount, activity and stability of enzymes. Considering size and charge on surface of DhaA, a suitable support based on molecular sieve SBA-15 was designed. The preparation process included hydrothermal synthesis, pore expansion and surface functionalization. An amino-modified support with disordered structure was finally achieved; whose pore size and window size were 5.6 nm and 3.8 nm respectively. The high loading and low leakage amount of DhaA were achieved by being adsorbed in this designed support. The catalytic activity and conformation of DhaA were still kept after adsorption. More importantly, the adsorbed DhaA had significant stability improvement in extreme denaturation conditions such as low pH, 3M of urea, 40% DMSO, and 30 days storage at room temperature. All the results suggested that it's feasible to enhance the stability of enzymes by designing the appropriate adsorption support. [ABSTRACT FROM AUTHOR]

The Løren tunnel is a road tunnel at Ring road 3 in Oslo, Norway. The tunnel has a length of 915 m in rock, has two tubes with three lanes and breakdown fields, and was first opened in 2013. For rock support in the case of weak rock masses, ribs of reinforced sprayed concrete (RRS) were used. The scope of this article is to present and analyse the results of a measurement programme carried out on three of these ribs. This is done by focusing on deformations in the rock and the support function of the ribs due to these deformations. The instrumented RRS had strain meters installed in the reinforcement and the concrete. From the surface above the RRS, multipoint borehole extensometers were placed to survey the soil and rock mass deformations caused by tunnel advancement. In addition, 2D and 3D rock stress measurements and rock property testing were conducted. The measurements and numerical modelling show that the deformations are too small to cause a considerable load on the installed support construction and that the 2D stress measurements seem to best fit the in-situ stress conditions. The rock mass quality in the area of this study is on the verge of where one usually starts using reinforced ribs. It is concluded that the RRS are not required because of deformations in the rock but, rather, because of the need to lock blocks, increase the friction in joints and prevent movement in larger filled joints. For this purpose, the RRS should probably be designed differently to get the most out of the materials used. [ABSTRACT FROM AUTHOR]

Based on the measured in-situ stress, the stress, displacement and plastic zone distribution in surrounding rock of the eastern 2# ventilation roadway of a mine in Shanxi are analyzed by using the generalized plane strain model, Mohr-Coulomb strength criterion and FLAC3D software. And it is considered that the stress concentration of surrounding rock is significantly affected by the circumferential stress in the range of 0~3m and the radius of plastic zone is 5m. Both of them have strong uniformity in distribution and it is approximately located in the direction of 135°-315°, showing the asymmetric characteristics. Combining with the influence characteristics of in-situ stress on the coal seam roadway, an asymmetric support scheme for roadway section is proposed. The practice shows that the support is effective, which provides theoretical guidance for the design and optimization of support parameters of roadway with similar engineering conditions. [ABSTRACT FROM AUTHOR]

This paper aims at studying the mechanism of deformation and instability of coal roadway subjected to largespan complex roof under deep-buried condition. Based on a case study of the reconstructed roadway of Cheji Coal Mine 2614 working face, the deformation of roadway surrounding, which combines pressure arching theory and numerical simulation method is studied. The roadway support scheme with "anchor (cable) + metal mesh + M-strip + single-prop" is designed and used for in-situ testing. The results show that the instability of the surrounding rock mass with large-span complex roof tunnel is composed of four stages: layered shearing, flexural separation, breakage breaking and arching. The height of the roadway arching reaches 2.5-3.8 m. Furthermore, after the span of roadway is larger than 6 m, the deformation of the surrounding rock and the development of the plastic zone significantly increased. The in-situ measurements show that the deformation of the surrounding rock with proposed support scheme is less than 100 mm. The tension stresses of bolt and anchor cable are less than 60 kN and 350 kN. The pressure of the single-prop with this support scheme is less than 13 MPa. A good support result is obtained with the proposed support design. [ABSTRACT FROM AUTHOR]

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• The deformation and failure characteristics of tunnels in Chengdu-Lanzhou railway are studied. • A modeling method is proposed considering both interlayer bedding planes and intralayer joints. • The evolution mechanism and inducement of four types of crack distribution are analyzed. • Case studies are conducted by using the proposed method. • Provide reference for support designs in layered surrounding rock. Tunnelling through layered rock mass with high geo-stress often leads to large deformation disasters, including rock collapses and structural failures. This study investigates the asymmetrical deformation and failure behaviors of deep tunnels in layered phyllite strata in Chengdu-Lanzhou railway (China). It has been observed that the mechanical behavior of these tunnels exhibits evident correlations with the orientations between geo-stress conditions and bedding plane. For in-depth analysis, a modeling method was first proposed considering the difference between interlayer bedding planes and intralayer joints. The excavation disturbance behaviors of unsupported tunnels with various bedding angles, such as deformation characteristics, crack generation and propagation, and stress distribution, were simulated and compared with on-site phenomena. Afterward, the crack distributions were classified into four typical types based on simulation results, and their causes, differences, characteristics, and evolutionary process mechanisms were also systematically analyzed. Additionally, the asymmetric failure caused by the weak plane effect was investigated and discussed. The results revealed that the bedding angle, the direction of principal stress and the effect of layer thickness primarily influenced the failure patterns of layered surrounding rock, which resulted in variations in both the direction and depth of failure. Engineering practice demonstrated that the classification method, based on the proposed numerical modeling approach, can serve as a valuable reference for tunnel support design. [ABSTRACT FROM AUTHOR]