The reasonable value of good gradation characteristic parameters is key in designing and optimising soil-rock mixed high fill embankment materials. Firstly, the DJSZ-150 dynamic-static large-scale triaxial testing instrument was used for triaxial compression shear tests on compacted skeleton structure soil-rock mixture standard specimens. The changes in strength and deformation indicators under different gradation parameters and confining pressure were analysed. Then, based on the Janbu empirical formula, relationships between parameters K, n, and (sigma 1-sigma 3)ult and the coefficient of uniformity Cu and coefficient of curvature Cc were explored. Empirical fitting formulas for Duncan-Chang model constants a and b were proposed, establishing an improved Duncan-Chang model for soil-rock mixtures considering gradation characteristics and stress states. Finally, based on significant differences in particle spatial distribution caused by gradation changes, three generalised models of matrix-block stone motion from different particle aggregation forms were proposed. Results indicate the standard specimen's strength and deformation indicators exhibit significant gradation effects and stress-state correlations. The improved Duncan-Chang model effectively simulates the stress-strain relationship curve under different gradations and confining pressure, with its characteristics explainable based on the matrix block stone motion generalised model.

A series of large-scale (1:13) model tests of multi-stage loading and unidirectional multi-cycle loading were conducted on semi-rigid piles before and after cement-soil reinforcement in clay. The difference of ultimate bearing capacity between unreinforced and reinforced piles under different criterions is discussed, and their bending moment and displacement distribution rules are revealed. Meanwhile, the cyclic bearing behaviour of the unreinforced and reinforced piles are compared and analyzed, including cyclic load-displacement response, unloading stiffness, cumulative peak & residual displacement, peak & locked in moment. The test results show that the ultimate bearing capacity of the large diameter pile is increased by 34.4 % and the initial stiffness is increased by 56.8 % (reinforced width is 3D and depth is 1D) in the multistage loading test. Comparing the monotonic and cyclic load-displacement curves of unreinforced and reinforced piles obtained by multi-stage loading test and unidirectional multi-cycle loading test respectively, it is found that when the applied load is small, the curve obtained from multistage loading test is almost coincident with the first cycle envelope of all load levels in 1-way multi-cycle loading test, indicating that the cyclic effect is not significant. As the load increases, the difference between the curves becomes larger, indicating that the cyclic loading of higher amplitude causes greater soil disturbance. In addition, after applying cement-soil to the shallow soil around monopile, cement-soil reinforced pile exhibits a more rigid response, specifically manifested as an initial unloading stiffness of 1.76 times that of unreinforced pile, and a slower stiffness degradation rate. Meanwhile, the cyclic peak displacement & residual displacement accumulation of reinforced piles are smaller than that of the unreinforced pile, thereby reducing the development of the locked in moment.

The shear behavior of gravel-block soil (GBS) is unique and significant for evaluation the failure mechanism of GBS landslide on the Qinghai-Tibet Plateau. This study focuses on interpreting the shear behavior observed in the GBS during large-scale direct shear tests conducted on a landslide in Jiacha County, Tibet, China. The tests considered coarse particle content (CPC), dry density, and moisture conditions. Additionally, a discrete element numerical model, scaled to match the laboratory testing dimensions, was developed to simulate the large-scale direct shear tests on GBS. Results indicated that an increase in CPC improves the strength of the GBS, as it enhances the framework strength through interlocking between gravel blocks and between gravel blocks and the soil mass. The critical CPC for shear failure of the GBS exhibits a decreasing trend as the dry density increases. Furthermore, particle crushing rate (PCR) of the GBS is positively correlated with CPC, vertical pressure, and dry density. The simulation results show good agreement with the test results, providing insights into the damage-shear fracture mechanism of typical GBS under large-scale direct shear tests. The research outcomes provide a theoretical basis for the prevention and control of geological hazards in the Qinghai-Tibet Plateau.

The construction industry faces significant challenges, including the urgent need to minimize environmental impact and develop more efficient building methods. Additive manufacturing, commonly known as 3D-printing, has emerged as a promising solution due to its advantages, such as rapid fabrication, design flexibility, cost reduction, and enhanced safety. This technology enables the creation of structures from digital models through automated layering, presenting opportunities for mass production with innovative materials and architectural designs. This article focuses on developing eco-friendly earthen-based materials stabilized with 9 % cement and 2 % rice husk (RH) for large-scale 3D-printed construction. The raw materials were characterized using geotechnical tests for soil, water absorption tests for natural fibers, and SEM-EDS to examine their microstructure and elemental composition. Key properties such as rheology, printability (pumpability and extrudability), buildability, and compressive strength were evaluated to ensure the material's optimal performance in both fresh and hardened states. By utilizing locally sourced materials such as soil and rice husk, the mixture significantly reduces environmental impact and production costs, making it a sustainable alternative for large-scale 3D-printed construction. The material was integrated into architectural and digital fabrication techniques to construct a bioinspired housing prototype showcases the practical application of the developed material, demonstrating its scalability, adaptability, and suitability for innovative and costeffective real housing solutions. The article highlights the feasibility of using earthen-based materials for sustainable 3D-printed housing, thereby opening new possibilities for advancing greener construction practices in the future.

Lakes are commonly accepted as a sensitive indicator of regional climate change, including the Tibetan Plateau (TP). This study took the Ranwu Lake, located in the southeastern TP, as the research object to investigate the relationship between the lake and regional hydroclimatological regimes. The well-known Budyko framework was utilized to explore the relationship and its causes. The results showed air temperature, evapotranspiration and potential evapotranspiration in the Ranwu Lake Basin generally increased, while precipitation, soil moisture, and glacier area decreased. The Budyko space indicated that the basin experienced an obviously drying phase first, and then a slightly wetting phase. An overall increase in lake area appears inconsistent with the drying phase of the basin climate. The inconsistency is attributable to the significant expansion of proglacial lakes due to glacial melting, possibly driven by the Atlantic Multidecadal Oscillation. Our findings should be helpful for understanding the complicated relationships between lakes and climate, and beneficial to water resources management under changing climates, especially in glacier basins.

The recent upsurge in metro construction emphasizes the necessity of understanding the mechanical performance of metro shield tunnel subjected to the influence of ground fissures. In this study, a largescale experiment, in combination with numerical simulation, was conducted to investigate the influence of ground fissures on a metro shield tunnel. The results indicate that the lining contact pressure at the vault increases in the hanging wall while decreases in the footwall, resulting in a two-dimensional stress state of vertical shear and axial tension-compression, and simultaneous vertical dislocation and axial tilt for the segments around the ground fissure. In addition, the damage to curved bolts includes tensile yield, flexural yield, and shear twist, leading to obvious concrete lining damage, particularly at the vault, arch bottom, and hance, indicating that the joints in these positions are weak areas. The shield tunnel orthogonal to the ground fissure ultimately experiences shear failure, suggesting that the maximum actual dislocation of ground fissure that the structure can withstand is approximately 20 cm, and five segment rings in the hanging wall and six segment rings in the footwall also need to be reinforced. This study could provide a reference for metro design in ground fissure sites. (c) 2025 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/ 4.0/).

This article presents the authors' experience with large-scale shaking table tests conducted in Japan using the E-Defense shaking table. The discussion focuses on four criticisms often addressed regarding the utilities of large-scale shaking table tests. Potential solutions to mitigate such criticisms are discussed based on shaking table tests conducted for a pair of three-story wooden houses. The first criticism is that the test specimen anchored rigidly to a rigid shaking table is not a reproduction of actual structures supported by soils and foundations. A model ground was developed in a large sandbox, which occupied about 85% of the total specimen weight, supported the house, and the entire soil-structure system was shaken. Considerable sliding occurred, having lessened the earthquake forces exerted and resultant damage to the superstructure. The second criticism is that a single specimen test, regardless of its size, cannot provide sufficient information for generalizing the behavior and performance. Empirical equations between the maximum story drift and the change in the natural frequency were developed from a series of shaking table tests. Using such empirical equations might promote quick damage assessment of individual houses when suffering from actual earthquakes. The third criticism is the importance of public appeal and eventual support from the general public to secure the budget to operate large-scale testing facilities. The example test featured two nearly identical specimens placed on the table with different support conditions. The apparent difference in response revealed the effect of support conditions on seismic performance. The fourth criticism is the importance of increasing the number of experimental projects to balance the operation budget. Most of the preparation in the example test was accomplished in an open yard adjacent to the shaking table, and the test specimens were quickly assembled on the table using indoor cranes. The table occupation was four out of 35 weeks of the entire test duration.

Based on a prototype of the Beijing subway tunnel, this research conducts large-scale model experiments to systematically investigate the vibration response patterns of tunnels with different damage levels under the influence of measured train loads. Initially, the polynomial fitting modal identification method (Levy) and the model test preparation process are introduced. Then, using time-domain peak acceleration, frequency response function, frequency-domain modal frequency, and modal shape indicators, a detailed analysis of the tunnel's dynamic response is conducted. The results indicate that damage significantly amplifies vibration acceleration, with the amplification increasing with the severity of the damage. When the crack lengths are 2 cm, 4 cm, and 6 cm, the peak acceleration increases by 25.12%, 36.35%, and 50.29%, respectively, while adjacent segments show increases of 13%, 29%, and 45%. Damage decreases the tunnel structure's modal frequency, with the first two modal frequencies showing the most significant reductions of 9.87% and 7.34%, respectively. The adjacent segments show reductions of 7.7% and 4.2%. As the severity of the damage increases, the amplitude of the modal shape at the damaged location also increases, with the first modal shape rising by 43.37% for 4 cm damage compared to 2 cm damage and by 72.21% for 6 cm damage. The second modal shape increases by 9.04% and 26.51%, respectively. Additionally, the effectiveness of the polynomial fitting modal identification method (Levy) for tunnel structural damage detection was validated. Finally, based on the methods outlined above, the tunnel responses measured on-site in the Beijing metro were also analyzed. The findings of this study provide important theoretical support for the assessment and routine maintenance of metro tunnels.

Particle size distribution (PSD) of coral sand is a critical factor that influences the mechanical properties at the coral sand-geogrid (CS-GG) interface, which is affected by both particle breakage and various temperatures. However, relevant researches are scarce currently. This study conducts a series of large-scale interface shear tests on coral sand with three PSD ranges (0.25 similar to 1mm, 1 similar to 2mm, and 2 similar to 4mm) at varying temperatures (5 degrees C similar to 80 degrees C). Experimental results demonstrate that the IB value at the CS-GG interface ascends and then descends with the increase of PSD from 20 degrees C to 40 degrees C. The IB value at the interface descends and then ascends with the increase of PSD from 60 degrees C to 80 degrees C; The PSD curves at the interface indicate that the particle breakage degree of coral sand increases with rising temperature (5 degrees C similar to 40 degrees C); The larger PSD of coral sand, the smaller fractal dimensions (D) of the interface; A mathematical formulation of the relationship between the relative breakage rate (Br) and the D value at interfaces is presented, which considers temperature effects; The relationship between the total input energy (E) and the Br value has been expressed by empirical formulations with different PSD ranges, where the fitting curve for 2 similar to 4 mm coral sand exhibits a hyperbolic pattern.

Fault fracture zones, characterized by high weathering, low strength, and a high degree of fragmentation, are common adverse geological phenomena encountered in tunneling projects. This paper performed a series of large-scale triaxial compression tests on the cohesive soil-rock mixture (SRM) samples with dimensions of 500 mm x 1000 mm to investigate the influence of rock content P-BV (20, 40, and 60% by volume), rock orientation angle alpha, and confining pressure on their macro-mechanical properties. Furthermore, a triaxial numerical model, which takes into account P-BV and alpha, was constructed by means of PFC3D to investigate the evolution of the mechanical properties of the cohesive SRM. The results indicated that (1) the influence of the alpha is significant at high confining pressures. For the sample with an alpha of 0 degrees, shear failure was inhibited, and the rock blocks tended to break more easily, while the samples with an alpha of 30 degrees and 60 degrees exhibited fewer fragmentations. (2) P-BV significantly affected the shear behaviors of the cohesive SRM. The peak deviatoric stress of the sample with an alpha of 0 degrees was minimized at lower P-BV (60%). Based on these findings, an equation correlating shear strength and P-BV was proposed under consistent alpha and matrix strength conditions. This equation effectively predicts the shear strength of the cohesive SRM with different P-BV values.