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A new luminescent CdII compound, poly[[μ2-1,4-bis(1H-imidazol-1-yl)benzene]{μ2-5-[(3-carboxylphenoxy)methyl]isophthalato}cadmium(II)], [Cd(C16H10O7)(C12H10N4)] n or [Cd(HL)(1,4-bib)] n {H3 L is 5-[(3-carboxyphenoxy)methyl]isophthalic acid and 1,4-bib is 1,4-bis(1H-imidazol-1-yl)benzene}, I, has been synthesized successfully from CdII and a semirigid tricarboxylic ligand under hydrothermal conditions. Structure analysis shows that I is a two-dimensional structure with the point symbol {44.62}. The three-dimensional framework is constructed by O—H...O hydrogen bonds and π–π stacking interactions. Furthermore, the obtained CdII compound displays high solvent stability and excellent thermal stability, as shown by powder X-ray diffraction and thermogravimetry measurements. Studies of the luminescence properties reveal that compound I can act as a promising luminescent sensor for detecting FeIII cations and CrVI oxyanions with high selectivity and low detection limits (0.19 µM for Fe3+ and 1.13 µM for Cr2O7 2−), and is additionally free from the interference of other ions. The mechanism of selective quenching was studied by measuring the UV–Vis absorption of the host compound and the target analytes.

The performance of a structurally dissipating rock-shed (SDR) depends largely on the capacity of its energy dissipators. At present, most energy dissipators are made of metals, which dissipate energy by unrecoverable plastic deformation. Therefore, they are not able to recover their energy-dissipation capacity after deformation under rockfall impact. However, a rockfall usually disintegrates into pieces when it rolls down from a higher position and results in multiple rockfall impacts. An energy dissipator with self-recovery capability is therefore more suitable for ensuring the safety of SDRs. Replacing metal with polyurethane (a hyperelastic material with remarkable self-recovery capability) can provide self-recovery capability for energy dissipators, making them more suitable for resisting multiple rockfall impacts. In this work, polyurethane was manufactured into two types of energy dissipators: cylindrical and cubical. Full-scale falling rock impact tests and dynamic numerical simulations were conducted to study the mechanical response of the energy dissipators. In addition, in order to ensure the accuracy of the simulation, the dynamic mechanical properties of the polyurethane were tested and its dynamic constitutive model was established. The experimental and simulation tests have clarified the advantages of the polyurethane energy dissipator. We also summarized the practical considerations in the design of energy dissipators.

This paper presents a study in which triaxial tests were performed on loess soil reinforced with natural roots. Triaxial compression tests were performed on soil specimens with root biomass of 0.25, 0.5, 1.0, and 1.25% and subsequently consolidated at various confining stresses under drained and undrained conditions. The results are presented in terms of monotonic stress–strain behavior, volumetric behavior, failure envelope, and shear strength parameters. The test results showed that the inclusion of roots required higher confining stress to prevent failure. The reinforced specimen showed continued mobilization of dilatancy in drained and undrained conditions and resulted in exhibiting higher peak deviator stress compared to the unreinforced specimen. The specimen with the lowest root biomass exhibited the least increments in the hardening response, while the specimen with the largest root biomass showed the highest hardening response. The addition of roots decreased the contractancy of soil in both drained and undrained condition. Under the same root content and confining pressure, the shear strength in an undrained condition is much higher as compared to drained conditions. The largest improvement in soil's mechanical behavior was observed at smaller confining pressure, i.e., 100 kPa in both drained and undrained conditions. The addition of roots also increases the initial yielding of the soil, which is the function of roots biomass. The output of this research will provide a foundation for the future development of the predictive constitutive model for soil–root composite and its applications to slope stability.

As a common phenomenon in granular flow, grain segregation plays a great role in affecting the behavior of granular soil by causing a great change of grain-void distribution in granular soil. This paper presents an experimental study on the influence of grain segregation on the behavior of sand, by a number of triaxial tests to interpret the characteristic behavior, friction and dilatancy behavior, excess pore water pressure behavior and critical state behavior of sand incorporating grain segregation. An index - grain segregation index Igs was proposed to quantify grain segregation. Grain segregation affected greatly the characteristic behavior of sand, causing the movement of void ratio-dilatancy relation of sand towards the increase of void ratio and dilatancy of sand. In the drained tests, the mobilized friction angle of sand showed a decrease followed by an increase but the mobilized dilatancy angle of sand increased, with increasing grain segregation index. An increase in grain segregation index impaired the basic friction of sand. In the undrained tests, the mobilized friction angle of sand showed an increase followed by a decrease with increasing grain segregation index. However, grain segregation caused an increase of the mobilized dilatancy of sand followed by a different development. An increase in grain segregation resulted in a higher summit of the dilatancy of sand but with a faster decrease along axial strain. In the q-p′ plane, grain segregation caused a reciprocating rotation of the dilatancy line and failure line of sand. Grain segregation resulted in enhancement of the peak-state dilatancy of sand, affecting greatly peak-state friction angle and peak-state basic friction angle of sand as well as the normalized excess pore water pressure. The excess friction angle of sand showed an increase followed by a decrease in the drained tests but increased linearly in the undrained tests, with increasing grain segregation index. The excess friction angle-over-maximum dilatancy angle of sand decreased in up convexity while increasing grain segregation index. Grain segregation resulted in rotation and translation of the critical state line of sand in the e-p′α=0.7 plane. However, in the q-p′ plane, the critical state line of sand showed an anticlockwise rotation followed by a clockwise rotation with increasing grain segregation index.

Be aimed at the development and application of aerospace high-temperature resistant ceramic fiber felt, in this paper, as the common ceramic fiber felt in the field of high temperature resistance, quartz fiber felt, high silica fiber felt and mullite fiber felt were compared. The microstructure, thermal insulation, temperature resistance and mechanical properties were analyzed respectively, the performance advantages and disadvantages of three kinds of ceramic fiber felt were given, and its internal causes were studied. The results show that, the temperature resistance of mullite fiber felt is better than that of quartz fiber felt and high silica fiber felt, mainly due to its polycrystalline mullite structure, the thermal insulation performance of mullite fiber felt and high silica fiber felt is better than quartz fiber felt at high temperature, mainly due to the thermal reflection of polycrystalline mullite and the small pore structure of high silica fiber felt, the compressibility of quartz fiber felt is better than high silica fiber felt and mullite fiber felt.

Glacial debris flows (GDFs) often occur in alpine regions that are subject to rapid climate change, and pose a serious threat to road systems. However, the ways that climate change impacts GDF risks along road systems remain poorly understood. Aierkuran Gully, located in eastern Pamir along Karakoram Highway (KKH), is a hotspot for GDF activity and climate change, and was thus selected to investigate the GDF risk to road systems under climate change conditions. RegCM4.6 climate data for northwestern China were selected as climate projections during baseline (2011–2020) and future periods (2031–2040) under the Representative Concentration Pathway (RCP) 8.5. To reflect the coupling effect of rainfall and melt water that triggers GDF, a glacial hydrological model DETIM that considers both factors was applied to calculate the peak debris flow discharge. A FLO-2D model was calibrated based on high-quality data collected from a detailed field investigation and historical debris flow event. The FLO-2D model was used to simulate the debris flow depth and velocity during baseline and future periods under RCP8.5. The debris flow hazard was analyzed by integrating the maximum flow depth and momentum. Road structure vulnerability was further determined based on the economic value and susceptibility of hazard-affected objects. The GDF risk along KKH was assessed based on the GDF hazard and vulnerability analysis. Our results show that climate change would lead to amplified peak debris flow discharge, trigger higher-magnitude GDF, and induce more severe damage and threats to the road system. Compared with the baseline period, the debris flow damage risk for culverts and bridges would increase and the areas that inundate the road and pavement would expand. Our findings provide valuable insights for the development of mitigation strategies to adapt road systems to climate change, especially in alpine regions with highly active GDFs.

A new luminescent Cd

This paper presents a laboratory experimental study on particle breakage of sand subjected to friction and collision, by a number of drum tests on granular materials (silica sand No. 3 and ceramic balls) to investigate the characteristics of particle breakage and its effect on the characteristics of grain size distribution of sand. Particle breakage increased in up convexity with increasing duration of drum tests, but increased linearly with increasing number of balls. Particle breakage showed an increase, followed by a decrease while increasing the amount of sand. There may be existence of a characteristic amount of sand causing a maximum particle breakage. Friction tests caused much less particle breakage than collision tests did. Friction and collision resulted in different mechanisms of particle breakage, mainly by abrasion for friction and by splitting for collision. The fines content increased with increasing relative breakage. Particle breakage in the friction tests (abrasion) resulted in a sharper increase but with a smaller total amount of fines content in comparison with that in the collision tests (splitting). For the collision tests, the fines content showed a decrease followed by an increase as the amount of sand increased, whereas it increased in up convexity with increasing number of balls. The characteristic grain sizes D 10 and D 30 decreased in down convexity with increasing relative breakage, which could be described by a natural exponential function. However, the characteristic grain sizes D 50 and D 60 decreased linearly while increasing the relative breakage. In addition, the coefficients of uniformity and curvature of sand showed an increase followed by a decrease while increasing the relative breakage.

This paper presents an experimental investigation of mobility and deposition characteristics of dry granular flow, by a number of flume tests on silica sand no. 3 and silica sand no. 7, to interpret the effects of angle of slope, granular volume, cushion, granular structure, and granular size on the mobility and deposition characteristics of granular flow. Along a given slope, an increase of the amount of sand impaired its mobility. However, for a given amount of sand along a slope, an increase of the angle of slope resulted in a V-shaped change of the angle of mass center movement, implying the existence of a characteristic combination of the angle of slope and the amount of sand to yield the maximum mobility of granular flow. The angle of mass center movement increased while increasing the thickness of cushion, showing that the cushion impaired the mobility of granular flow. Granular structure using the mixed structures of silica sand no. 3 and silica sand no. 7 affected greatly the mobility of granular flow, by showing an inverted structure in the near runout area with the deposition of the materials in the upper half of original grading structure in the far runout area for the inverse grading structure and normal grading structure. The mobility of granular flow increased with the change in turn of the inverse grading structure, the uniform structure, and the normal grading structure. The increase of the grain sizes of granular material enhanced its mobility. In addition, the angle of mass center movement showed a more reliable assessment for the mobility of granular flow in comparison with the angle of maximum mass movement.

On June 17, 2020, an unexpected rainstorm struck the Meilong valley, which is located in Danba County, Sichuan Province, China. The cumulative rainfall of this short-duration event reached 38.1–42.4 mm and triggered the Meilong debris flow. The Meilong debris flow rushed into the valley and forced the Xiaojinchuan (XJC) River to flow along the foot of the ancient Aniangzhai (ANZ) landslide. Intense erosion reactivated the ancient ANZ landslide, producing a reactivated area of 0.62 km2. Subsequently, emergency investigation and monitoring were conducted to monitor its deformation because unstable landslide conditions could pose a serious threat to the safety of lives and property downstream. Emergency monitoring over 20 days (June 23, 2020–July 12, 2020) indicated that the reactivated deposit decelerated and entered the constant deformation state; careful attention should be paid to this reactivated deposit.

The maximum impact force of granular flow and its action point on a rigid barrier are the key indices of the anti-slip and the anti-overturning calculation, respectively. On the basis of the present impact force models and the observation in model experiments, this paper proposes a new semi-empirical impact force model focusing on the normal impact force and its point of action. By comparing the analytical solution and the experimental results, the new semi-empirical analytical model can estimate the normal impact force composed of both dynamic and static components with an error margin within ± 20% compared with the experimental results and so is for the corresponding point of action and tangential force. To calculate the residual force generated only by the static dead zone, the static friction angle between the dead zone and the chute base should be less than what was measured under kinetic conditions. Based on a large number of tests, it was found that assuming that the reaction force generated by the chute base operates at 2/3 of the deposition length makes the estimated normal impact force best suited to the experimental results.

Plant roots mechanically enhance the strength of soil and improve slope stability through anchoring. Given the popularization of ecological slope-protection technology, a quantitative study of how roots help to anchor soil is highly pertinent. The object of the present study is thus to investigate how roots and soil combine to affect the mechanical properties of the root-soil interface. Toward this end, pullout experiments of cedar roots of different diameters in soils of different density were conducted. The experimental results show that the maximum pullout force increases significantly with increasing root diameter, but only slightly increases with increasing soil density, which indicates that the root diameter has a greater impact on the maximum pullout force than soil density. Next, based on studies of fiber-reinforced composites, a root-soil pull-out model was proposed to study the evolution of shear stress on root-soil interface. This approach ensures that the model accurately reflects the dynamic stress distribution evolution at the root-soil interface and can calculate the pullout process of embedded root from soil. The accuracy of the model is verified by comparing the calculated results with experimental results. Finally, how soil density and root diameter affect the anchoring force was analyzed. The results indicate that the maximum anchoring force increases linearly with increasing root diameter, but nonlinearly with increasing soil density until reaching a fixed value. These results show that the root soil pull-out model has significant practical value in slope protection.

Kathmandu Kyirong Highway (KKH) is one of the most strategic Sino-Nepal highways. Low-cost mitigation measures are common in Nepalese highways, however, they are not even applied sufficiently to control slope instability since the major part of this highway falls still under the category of feeder road, and thus less resources are made available for its maintenance. It is subjected to frequent landslide events in an annual basis, especially during monsoon season. The Gorkha earthquake, 2015 further mobilized substantial hillslope materials and damaged the road in several locations. The aim of this research is to access the dynamic landslide susceptibility considering pre, co and post seismic mass failures. We mapped 5,349 multi-temporal landslides of 15 years (2004–2018), using high resolution satellite images and field data, and grouped them in aforementioned three time periods. Landslide susceptibility was assessed with the application of ‘certainty factor’ (CF). Seventy percent landslides were used for susceptibility modelling and 30% for validation. The obtained results were evaluated by plotting ‘receiver operative characteristic’ (ROC) curves. The CF performed well with the ‘area under curve’ (AUC) 0.820, 0.875 and 0.817 for the success rates, and 0.809, 0.890 and 0.760 for the prediction rates for respective pre, co and post seismic landslide susceptibility. The accuracy for seismic landslide susceptibility was better than pre and post-quake ones. It might be because of the differences on completeness of the landslide inventory, which might have been possibly done better for the single event based co-seismic landslide mapping in comparison with multitemporal inventories in pre and post-quake situations. The results obtained in this study provide insights on dynamic spatial probability of landslide occurrences in the changing condition of triggering agents. This work can be a good contribution to the methodologies for the evaluation of the dynamic landslide hazard and risk, which will further help to design the efficient mitigation measures along the mountain highways.

This study aimed to illustrate the seismic response and instability process of a double-row anti-slide pile-reinforced bridge foundation and gravel landslide. Selecting the gravel slope of Jiuzhai Valley along the under-construction Chengdu-Lanzhou high-speed railway as the site prototype, large-scale shaking table tests were first conducted at a similitude ratio of 1:70, with sine waves and El Centro waves as the seismic wave inputs. The amplitudes of the input seismic waves were increased, while the acceleration, dynamic earth pressure, and strain distribution were monitored in the gravel landslide. The dynamic response patterns of anti-slide pile-reinforced bridge foundations in gravel landslides were illustrated. The front-row and back-row anti-slide piles should be a reasonable distance from the bridge foundation. The response acceleration manifested an elevation amplification effect with an increasing elevation in the slope behind the anti-slide piles. Back-row anti-slide piles reinforcing the bridge foundation can reduce the effect of landslide thrust on the bridge foundation and maintain a uniform distribution of earth pressure behind the bridge foundation, mitigating seismic effects. The dynamic earth pressure peaked at the top of the bridge foundation and then decreased along the depth. The back-row anti-slide piles displayed greater resonance coupling and unloading effects before and after reaching the load-carrying limit, respectively. In seismic strengthening design involving bridge foundations and gravel landslides, when the earthquake-induced resonance coupling effect on inclined, loosely packed land masses is fully considered, pre-reinforcement measures (e.g., high-pressure grouting and anchor spraying) should be carried out on the gravel slopes.

Frequent landslide events affect the Kathmandu Kyirong Highway (KKH), one of the most strategic Sino-Nepal highways, with multiple social effects. Amongst them, the impacts on local tourism, although being substantial, have not been studied so far. The aim of this research is to analyze the characteristics of such landslides and their influence on road damages and/or blockages as well as on local tourism industry. We analyzed the co-seismic landslides triggered by the Gorkha Earthquake, 2015 (7.8 Mw), the post-seismic landslides that occurred during the monsoons following the earthquake, as well as landslides which occurred or reactivated in 2018, with relation to the damage that they caused to the highway. High resolution satellite images from 2015 to 2018, and field data were used for the analysis. The Langtang avalanche that locates off the highway was also mapped due to its high impacts on tourism. Between 2015 and 2018, the number of road damaging landslides in the Betrawati-Rasuwagadhi section of KKH (where Dhunche and Syafrubesi towns are located) was 101 in the main track (MT) and 103 in the new track (NT), with respective average density of 1.46/km and 3.63/km. The dominant observed landslide types were debris slides and rock falls. Landslides were mostly concentrated in the locations with the following characteristics: 1) having higher elevated area, 2) being located with the ‘main central thrust’ and other lineaments’ belts, 3) belonging to the Proterozoic lesser Himalayan rocks, 4) having a slope gradient of 25°–45°, 5) having northern, western and southern slope aspect, 6) being subjected to average annual rainfall of higher than 1,000 mm, and 7) having less than 4 km distance from the past earthquake epicenters. The results further indicated that 7 rain-induced and 4 co- and post-seismic landslides have great impact on tourist flows. An impact analysis was also assessed through a door to door questionnaire survey with local hotel operators from Dhunche and Syafrubesi towns (n = 29 + 31). The results reveal that out of six rigorously affected sectors by landslides leading to road blockage, tourism business is the most impacted livelihood sector in these towns. The reduction of visitors in different hotels ranged from 50%–100% in Dhunche and 70%–100% in Syafrubesi for the first year aftermath of the tremor. This is higher than the respective 5%–50% tourist reduction due to rain-induced landslides. Using as a reference the base year 2014, the income loss of hotels in both towns was found to be 50%–100% in 2015, 20%–100% in 2016, 5%–75% in 2017, and similar to 35% in 2018. These results provide insights on the synergic effect of contributing factors for cut slope as well as down slope instability along mountainous motorways and their impact on income sources for local communities.

Landslides are prevalent, regular, and expensive hazards in the Karakoram Highway (KKH) region. The KKH connects Pakistan with China in the present China-Pakistan Economic Corridor (CPEC) context. This region has not only immense economic importance but also ecological significance. The purpose of the study was to map the landslide-prone areas along KKH using two different techniques-Analytical Hierarchy Process (AHP) and Scoops 3D model. The causative parameters for running AHP include the lithology, presence of thrust, land use land cover, precipitation, and Digital Elevation Model (DEM) derived variables (slope, curvature, aspect, and elevation). The AHP derived final landslide susceptibility map was classified into four zones, i.e., low, moderate, high, and extremely high. Over 80% of the study area falls under the moderate (43%) and high (40%) landslide susceptible zones. To assess the slope stability of the study area, the Scoops 3D model was used by integrating with the earthquake loading data. The results of the limit equilibrium analysis categorized the area into four groups (low, moderate, high, and extremely high mass) of slope failure. The areas around Main Mantle Thrust (MMT) including Dubair, Jijal, and Kohistan regions, had high volumes of potential slope failures. The results from AHP and Scoops 3D techniques were validated with the landslides inventory record of the Geological Survey of Pakistan and Google Earth. The results from both the techniques showed similar output that coincides with the known landslides areas. However, Scoops 3D provides not only susceptible zones but also the range of volume of the potential slope failures. Further, these techniques could be used in other mountainous areas, which could help in the landslide mitigation measures.

Carbon aerogel composites have been prepared by condensation polymerization and high temperature pyrolysis. The morphology of carbon aerogel is characterized by SEM. The pore structure is characterized by N2 adsorption-desorption technique. The thermal insulation properties of carbon aerogel composites are tested. Carbon aerogel composites show good thermal insulation and high temperature resistance in inert atmosphere The results show that they are suitable for applications in aerospace thermal protection industry.

As its much lower thermal conductivity than other usual materials, Silica aerogel is a potentially efficient heat insulation material with the lowest bulk density. However, it is transparent for infrared light when used in high temperature. Herein, titanium oxide was added in the silica aerogel by in-situ blending. The dispersion property of titanium oxide particles, microstructure mechanical property, thermal conductivity, and thermal insulation were investigated. The results of this in-situ blending process indicated a potential application value in aerospace thermal protection industry.

Landslide events in Karakorum ranges are frequent and have already damaged local infrastructures and roads. In the hilly regions, landslide characterization and predicting its deposition pattern are essential for accurate engineering hazard assessment. To this end, numerical simulation models are commonly used tools. However, appropriate model parameters are often not available to predict and generate real landslide scenarios. This work describes the use of multidisciplinary techniques to estimate the model parameters for a slope prone to landslide and simulate the hazard level. The first important parameter, landslide boundary, and dynamics were estimated from temporal satellite images by identifying the areas with prominent deformations using the Interferometric Synthetic Aperture Radar (InSAR) technique. The susceptible subsurface strata volume and the possible landslide initiation depth were determined with the electrical resistivity method. In addition, voxel 3D electrical resistivity models were created to present the depth of the existing rupture and the nature of subsurface strata. The soil mechanical parameters were calculated during field visits and laboratory tests. The parameters adopted from different techniques helped simulate the susceptible landslide volume and initiation depth. These parameters are a critical factor in developing an accurate high-speed landslide model through numerical simulation. The applied methodology is vital to understand the dynamics of a particular slope and perform accurate engineering hazard assessment with numerical simulation. The results are essential to predict the potential deposition areas of the landslide event accurately, minimize the risk level, and take proactive mitigation measures.

According to field investigations, the failure surfaces of a large number of hard thin-layered anaclinal rock slopes are bilinear-type surfaces, and the overall failure of such slopes is the results of the evolution of cross joints in most cases. In order to realize accurate positioning of such actual failure surfaces, an optimal method, developed by the limit equilibrium theory and the minimum principle of Pan Jiazheng, for searching the bilinear-type failure surfaces of such slopes, was established. The failure surface was considered to be a surface at which the external force triggering the overall failure of a slope was the minimum value. The failure modes (shear sliding and bending tension failure) of rock strata were determined strictly by the failure criteria, and the amount of the failed strata was obtained accurately through a theoretical derivation with justifiable assumptions. The effects of cross joints on the stability of such slopes were taken fully into account. Based on the present computational framework, comparisons with other studies were carried out by taking Yangtai landslide. The results showed that the failure surface obtained with the proposed method compared well with the actual failure surface of Yangtai landslide and the safety factor of the stability of the slope was credible. Through the sensitivity analysis of the continuous ratio of rock strata, we found that with the decrease of the continuous ratio of rock strata, the safety factor of the stability of the slope decreased, and the slope was subjected to shallow damage.

This study aimed to illustrate the seismic performances of anti-slide pile-reinforced bridge foundations in landslides. Based on the anti-slide reinforcement project at Yousuotun along the Chengdu-Lanzhou high-speed railway under construction, shaking table tests were performed on a double-row anti-slide pile-reinforced bridge foundation and landslide model with a 1:40 similitude ratio. Given that the similitude law was satisfied, seismic waves with different frequencies and acceleration amplitudes were input as base excitations to monitor the responses of dynamic parameters: slope acceleration, earth pressure, and pile strain. The amplification effect of peak ground acceleration (PGA) was analyzed. The landslide thrust distribution characteristics and slope response processes were further studied to verify the seismic design of such bridge foundations in landslide-prone areas. The response acceleration of the slope subjected to seismic loads showed a nonlinear amplification “elevation effect”, “surface effect”, and “geological structure effect”. When the distance between the bridge foundation and the back-row anti-slide pile was small, the pier maintained a relatively large PGA amplification factor and was subjected to strong seismic loads. The landslide thrust was mainly borne by the upper part of the back-row anti-slide piles as its distribution changed from spoon-shaped to bow-shaped. Under high-intensity earthquake events, the load-bearing section of the bridge foundation should be strengthened at the sliding surface. Anti-slide piles can effectively limit the dynamic response of the landslide and weaken the seismic response of the slope. The results of testing this reinforcement are the first results proving that the seismic design of reinforced bridge foundations with anti-slide piles can be reliable.

Although weathered red mudstone (WRM) is widely distributed in the southwest of China, its suitability as a fill material for the subgrade bed of a high-speed railway (HSR) has not been comprehensively investigated. This paper presents the results of a field full-scale model testing of the cyclic loading and response of a railway track-subgrade system for the Dazhou-Chengdu Railway, where some WRM has been used in a newly designed subgrade structure. A control section of the HSR was also built using a traditional subgrade bed (Group A&B material) to compare the performances of the different sections. To better understand the dynamic characteristics and cumulative deformation of the two types of subgrade, the dynamic actions of different axle loads and different train speeds were simulated using specifically designed track-cyclic-loading equipment. The transverse and vertical distributions of the dynamic stress, dynamic displacement and acceleration of the track-subgrade system were measured and evaluated. The influence of the wheel axle load on the growth factor of the dynamic parameters, the vertical attenuation coefficient of the dynamic stress, and the effect of using WRM in the subgrade on the post-construction settlements were investigated. The tests enabled the development of cumulative settlement laws with railway loading for the two types of subgrade. Although the dynamic parameters and cumulative settlement of the WRM subgrade are always greater than those of better-quality material (Group A&B subgrade), they comply with HSR regulations. In conclusion, the results demonstrated that weathered red mudstone can be used as a filling material in the newly designed subgrade structure for HSRs.

The degree of mechanical reinforcement provided by plants depends upon its roots distribution in the soil and mechanical properties of the roots. The mechanical properties and distribution of root traits (root diameter and number) in the soil of the standing forest depends on the tree stem diameter. This variation of root traits with tree stem diameter is rarely investigated. Therefore, this research presents the effect of tree stem diameter on the distribution of roots within the standing forest of Cunninghamia in the Longchi forest area, Sichuan province, China. In this area, shallow landslides take place frequently. We investigated the root traits distribution for trees with different stem diameters, i.e., 220 mm, 320 mm, 450 mm, and 468 mm, to show the variation of roots distribution in the soil with stem diameter. The root architecture of the selected trees was studied by step excavation method of the root zone accompanied by measurement of roots physical parameters (roots number and roots diameter) and indices (roots area ratio (RAR), roots biomass (RB), and roots distribution (RD)). We measured the root&rsquo, s maximum tensile strength by performing root tensile tests in the laboratory. The field and laboratory-measured data were used to estimate the root cohesion by both the commonly used model Wu and Waldron Model (WWM) and Fiber Bundle Model (FBM). The results indicate that the tree stem diameter correlates with both the root distribution and the tensile strength. The roots indices and root cohesion increase with an increase in the diameter of the tree. Further, RAR decreases with depth and lateral distance from the tree stem, while the maximum values were observed in 10 cm depth. The relationship between roots diameter and roots tensile strength is established through power function. The average root cohesion estimated for a tree with stem diameter 220 mm is 23 kPa, 29 kPa for 320 mm, 54 kPa for 450 mm, and 63 kPa for 460 mm. This effect of stem diameter on the increase of soil shear resistance should be considered while evaluating the stability of slopes in standing forests. The comparison between WWM and FBM for investigated species suggests that WWM estimates the cohesion values greater than FBM by 65%.

Xinmo landslide buried the village and caused many casualties and property damage. After the landslide, a deformed block came into being on the left side of the landslide. Researchers mainly concentrated on the main body and the causes of the landslide without a systematic analysis of this block. This work is to discuss this block based on field investigation and UAV images. In the investigation, four scarps and three cracks were found. The lower two scarps indicated a downslope movement of the foot of the block, while the other two scarps and three cracks showed that main displacement of the block was towards to the free face formed in the landslide. Combined previous researches, it can be inferred that bedrock in the lower two scarps was the locking section, which stopped the movement of the block and the formation of the block can be divided into three stages. Then, two potential slipping direction were concluded and the FOS (Factor of Safety) were calculated with the Finite Element Method (FEM). Results show that the slip is more easily towards the free face which would do less harm. But it cannot be excluded that it would slip down the slope which could do much harm to the village and the road. So, monitoring is recommended on the foot of the block to get an advanced notice.

Gyirong serves as an important channel to Chine-Nepal Economic Corridor, which is also the only land route for China-Nepal trade since the 2015 earthquake. However, the Gyirong corridor suffers from glacier-related debris flow from every April to September because of the complex topographic features and the changing climate. Therefore, a susceptibility map in response to precipitation and temperature change is timely, not only to ensure the safe operation of this corridor, but also to provide decision-makers a guidance for hazard mitigation and environmental remediation. Conventional method is difficult to consider and link the meteorological factors (e.g. temperature and precipitation), topographies, ecological, geological conditions all together to produce the susceptibility map, as such, machine learning is utilised to conduct the analysis. Logistic Regression (LR) and Support Vector Machine (SVM) were firstly applied to evaluate their efficiency and effectiveness of the performance of producing the susceptibility map. In order to improve the fitting and prediction accuracy (ACC), genetic algorithm - support vector machine (GA-SVM) and certainty factor - genetic algorithm - support vector machine (CF-GA-SVM) were conducted based on the initial analysis results of receiver operating characteristics curve (ROC) and ACC. Through the analysis, it can be seen that over 61% of the study areas have a high susceptibility to debris flow, requiring an intensive attention from the local government. To further optimise the computational time, when dealing with small amounts of sample data, SVM is more efficient than LR, but CF-GA-SVM can achieve the highest AUC (Area Under Curve) and ACC values, 0.945 and 0.800, respectively. Overall, CF-GA-SVM model presents a relatively high robustness according to sensitivity analysis.

This study uses a geophysical technique to predict the future availability of water resources in Pakistan. When combined with pumping test data, this method can be used to delineate an aquifer system to determine the aquifer parameters, which can then be used for a region where pumping test data are not obtainable. For this purpose, an analytical relationship is applied with support from interpreted aquifer parameters and pumping test data. The results are verified by vertical electrical sounding (VES) in the Mandi Bahauddin District of Pakistan. Altogether, 28 sequences were carried out using the Schlumberger configuration, with the results showing that the subsurface formation consists of an alluvium lithology up to 183 m. The pumping tests of boreholes and VESs show that the aquifer strata include clay, silt, sand, kankar, and minor gravel mixed facies. The low hydraulic conductivity and transmissivity imply the presence of silt and clay, whereas high conductivity and transmissivity confirm the existence of sand or gravel. The results from pumping test data and resistivity data were used in a regression technique to develop a relationship for an aquifer system. The findings should contribute to the rapid estimation of the hydraulic properties of an aquifer and the rapid determination of aquifer characteristics.

Kathmandu-Kyirong highway, forced to bear recurrent mass failures, is currently the most important Sino-Nepal land route that built in difficult terrain of high tectonic belt, and extreme weather and climate system. Besides, young and weak geological settings and ongoing developmental activities further increase the frequency of landslide hazard. This route is also under the plan of upgrading not only as a high grade highway but also a strategic transboundary railway line. We mapped mass failure events of fifteen years (2004 to 2018) using multi-temporal high resolution satellite images and field investigation to analyze characteristics of landslides. Key informant interview (40), focus group discussion (5) and questionnaire survey (296) were done amongst residents of 8 on-road towns for the societal impact assessment. Four thousands five hundred and seventy seven landslides (31.68 km2) were mapped within the transportation corridor of 1682.5 km2. Mass failures of continuous activation for different time periods were of 6.3 km2 area. The density of landslides is high in late Paleozoic and pre-Cambrian lithological formations. Landslide occurrences were increased with incremental slope and relative relief. In steep slopes rock falls were dominant. Southern slopes that receive more solar radiation and rainfall have more mass failures. Most of the landslide events occurred in grassland, bushes and barren land. The runout that reached to the river system was 0.5% of the total failures. Stream proximity has shown reverse relation with land sliding, whereas distance from road has positive relation. It happened because most of the roads are in urban and sub-urban areas of flat landscape with few connections to mountainous belt. The epicenter proximity has also shown negative relationship with slope failures. Pre and post-quake events were increased with annual normal rainfall amount up to 3,000mm. Then slope failure started decreasing. In case of co-seismic landslides of 2015 Gorkha Nepal earthquake, the rainfall has negative influence because the earthquake event itself had occurred before the monsoon begun. Six major sectors – mobility of people, transportation of goods, health and education facilities, price hike and shortage of goods, tourism or other business loss, and agriculture production and market access were identified as the most influenced sectors when road blocked by mass failures. Effect on agriculture production and market access is major in Ramche, Grang-Mulkharka and Mahadevbensi and reduction of tourists flow is dominant in Dhunche and Syabrubensi towns. Responders considered the constantly road blocking landslides in the past, co-seismic mass failures of 2015 tremor and landslides of 2018 while evaluating the impacts. Because of annual cycle of concentrated landslide incidences, town dwellers have developed a coping mechanism for road blockage time which includes operation of one way vehicles to avoid damaged area, carry goods by foot from nearby markets, mentally prepare themselves for daily mobility by walking, keep stock of goods, and proper savings for buying expensive stuffs in local shops during road blockage.

As it is very difficult to construct conforming plate elements and the solutions achieved with conforming elements yield inferior accuracy to those achieved with nonconforming elements on many occasions, nonconforming elements, especially Adini’s element (ACM element), are often recommended for practical usage. However, the convergence, good numerical accuracy, and high computing efficiency of ACM element with irregular physical boundaries cannot be achieved using either the finite element method (FEM) or the numerical manifold method (NMM). The mixed-order NMM with background cells for integration was developed to analyze the bending of nonconforming thin plates with irregular physical boundaries. Regular meshes were selected to improve the convergence performance; background cells were used to improve the integration accuracy without increasing the degrees of freedom, retaining the efficiency as well; the mixed-order local displacement function was taken to improve the interpolation accuracy. With the penalized formulation fitted to the NMM for Kirchhoff’s thin plate bending, a new scheme was proposed to deal with irregular domain boundaries. Based on the present computational framework, comparisons with other studies were performed by taking several typical examples. The results indicated that the solutions achieved with the proposed NMM rapidly converged to the analytical solutions and their accuracy was vastly superior to that achieved with the FEM and the traditional NMM.

The objective of this study is to verify the feasibility of using centrifugal model tests to characterize the ground reaction response of a high-speed railway embankment to predict its ground settlement. To do so, a series of Centrifugal Model Tests (CMTs) of the embankment were performed to investigate the variation of ground reaction and corresponding derived modulus at different embankment ratios. The ground reaction determined from the CMTs was compared with those obtained from corresponding full-scale field tests of instrumented embankment. The results show that the ground reaction at the embankment centreline gradually approaches the embankment weight (γH) with increasing embankment ratio. Considering the embankment filling process with different embankment ratios, it seems inappropriate to employ the value of γH as the ground reaction without any correction in settlement prediction. Finally, the predictive capability of the proposed approach for embankment settlement estimation was assessed against the corresponding field measurements and those determined based on the calculation methods suggested in the current design standard in China. The results show that the proposed simple approach satisfactorily estimates the ground settlement of HSR embankments and its deviation of predicted settlements is below 11.9% compared with the data obtained from the field full-scale tests. However, the deviation of the result calculated by the current recommend design standard is 17.7%-148.3%.

The construction of a high-speed railway (HSR) in Southwest China is being hindered by a severe shortage of high-quality subgrade materials. However, red mudstone is widely distributed in the Sichuan Basin of China. The ability to use weathered red mudstone (WRM) to fill subgrade beds by controlling its critical stress and cumulative strain would enable substantial savings in project investments and mitigate damage to the ecological environment. To better understand the dynamic behaviour of WRM, both monotonic and cyclic triaxial tests were performed. The evolution of the cumulative strain vs. increased loading cycles was measured. The influences of confining pressure and loading cycles on the dynamic modulus, damping ratio, critical cyclic stress ratio (CSR), and dynamic stress level (DSL) were investigated. The relationship between the CSR and loading cycles under different failure strain criteria (0.1%-1.0%) was analysed. The prediction model of cumulative strain was also evaluated. The results indicated that the shear strength of WRM sufficiently meets the static strength requirements of subgrade. The critical dynamic stress of WRM can thus satisfy the dynamic stress-bearing requirement of the HSR subgrade. The critical CSR decreases and displays a power function with increasing confining pressure. As the confining pressure increases, the DSL remains relatively stable, ranging between 0.153 and 0.163. Furthermore, the relationship between the dynamic strength and loading cycles required to cause failure was established. Finally, a newly developed model for determining cumulative strain was established. A prediction exercise showed that the model is in good agreement with the experimental data.

In an effort to investigate the effects of relative roughness R n and mean particle size D50 on interface shear behavior between sand and steel, a series of monotonic interface were undertaken using a modified direct shear apparatus on various types of sand (having three different mean particle sizes (samples A [ D 50 = 1.590 mm], B [ D 50 = 1.020 mm], and C [ D 50 = 0.638 mm]) and steel plates (having five levels of relative roughness Rn varying from 0 to 2)). Various mechanical responses from the interface shear test, such as shear stress, vertical deformation, and friction angle, were evaluated through comparisons with the trends observed in the pure soil shear test. Similar shear behavior is found among the interface shear tests having different levels of R n . The maximum vertical deformation of interface shear test is less than that seen in the pure soil test, and the rough interface shear test also exhibits weaker shearing resistance than the pure soil shear test does. Furthermore, there exists a critical value of relative roughness R cr whose value is between 0.5 and 1 in the present study, such that the peak shear stress or friction angle φ can no longer be readily enlarged when Rn exceeds R cr . Moreover, the friction angles φ of samples A ( D 50 = 1.590 mm), B ( D 50 = 1.020 mm), and C ( D 50 = 0.638 mm) are approximately equal for any given R n , even though the specimens having different D 50 were used in the interface shear test. However, for the pure soil shear test, φ apparently increases with D 50 , indicating that D 50 directly affects φ obtained from the pure soil test. φ obtained from the interface shear test may be not of direct interest to D 50 but could depend on the coupling factor characterized by R n .

Quaternary silt is widely distributed in China and easily liquefies during earthquakes. To identify the influence of the dry density on the liquefaction behaviour of Quaternary silt, 40 cyclic triaxial liquefaction tests were performed on loose silt (dry density ρd=1.460 g/cm3) and dense silt (ρd=1.586 g/cm3) under different cyclic stress ratios (CSRs) to obtain liquefaction assessment criteria, determine the liquefaction resistance, improve the excess pore water pressure (EPWP) growth model and clarify the relationship between the shear modulus and damping ratio. The results indicate that the initial liquefaction assessment criteria for the loose and dense silts are a double-amplitude axial strain of 5% and an EPWP ratio of 1. The increase in the anti-liquefaction ability for the dense silt is more significant under lower confining pressures. The CSR of loose silt falls well within the results of the sandy silt and Fraser River silt, and the dense silt exhibits a higher liquefaction resistance than the sand-silt mixture. The relationships between the CSR and loading cycles were obtained at a failure strain of 1%. The EPWP development in the dense and loose silts complies with the “fast-stable” and “fast-gentle-sharp” growth modes, respectively. The power function model can effectively describe the EPWP growth characteristics of the dense silt. Finally, based on the liquefaction behaviour of silt, a suggestion for reinforcing silt slopes or foundations is proposed.