Loess has the characteristics of loose, large pore ratio, and strong water sensitivity. Once it encounters water, its structure is damaged easily and its strength is degraded, causing a degree of subgrade settlement. The water sensitivity of loess can be evaluated by permeability and disintegration tests. This study analyzes the effects of guar gum content, basalt fiber content, and basalt fiber length on the permeability and disintegration characteristics of solidified loess. The microstructure of loess was studied through scanning electron microscopy (SEM) testing, revealing the synergistic solidification mechanism of guar gum and basalt fibers. A permeability model was established through regression analysis with guar gum content, confining pressure, basalt fiber content, and length. The research results indicate that the addition of guar gum reduces the permeability of solidified loess, the addition of fiber improves the overall strength, and the addition of guar gum and basalt fiber improves the disintegration resistance. When the guar gum content is 1.00%, the permeability coefficient and disintegration rate of solidified soil are reduced by 50.50% and 94.10%, respectively. When the guar gum content is 1.00%, the basalt fiber length is 12 mm, and the fiber content is 1.00%, the permeability of the solidified soil decreases by 31.9%, and the disintegration rate is 4.80%. The permeability model has a good fitting effect and is suitable for predicting the permeability of loess reinforced with guar gum and basalt fiber composite. This research is of vital theoretical worth and great scientific significance for guidelines on practicing loess solidification engineering.

Loess is widely distributed in the northwest and other regions, and its unique structural forms such as large pores and strong water sensitivity lead to its collapsibility and collapse, which can easily induce slope instability. Guar gum and basalt fiber are natural green materials. For these reasons, this study investigated the solidification of loess by combining guar gum and basalt fiber and analyzed the impact of the guar gum content, fiber length, and fiber content on the soil shearing strength. Using scanning electron microscopy (SEM), the microstructure of loess was examined, revealing the synergistic solidification mechanism of guar gum and basalt fibers. On this basis, a shear strength model was established through regression analysis with fiber length, guar gum content, and fiber content. The results indicate that adding guar gum and basalt fiber increases soil cohesion, as do fiber length, guar gum content, and fiber content. When the fiber length was 12 mm, the fiber content was 1.00%, and the guar gum content was equal to 0.50%, 0.75%, or 1.00%, the peak strength of the solidified loess increased by 82.80%, 85.90%, and 90.40%, respectively. According to the shear strength model, the predicted and test data of the shear strength of solidified loess are evenly distributed on both sides of parallel lines, indicating a good fit. These findings are theoretically significant and provide practical guidance for loess solidification engineering.

In order to make clear the cracking reasons in arch dam of Xiaowan Hydropower Station during operation period, the approach to combine ANSYS with finite element program COCE‐3D is adopted. Firstly, the influence by element type and mesh size for the temperature field simulation result is analyzed. Subsequently, the three typical dam segments cut from Xiaowan arch dam are selected and the relevant finite element model is established; the effect of the measured diurnal air temperature on temperature field and temperature stress of arch dam is analyzed thoroughly. The results indicate that the temperature gradient in mass concrete becomes lower, whereas the affecting depth becomes deeper when the mesh size is too large. Therefore, it is advisable to use smaller size mesh to study the influence of the measured diurnal air temperature on the surface temperature distribution in mass concrete. The temperature of downstream zone in arch dam is significantly affected by air temperature; the changing laws of temperature field and temperature stress with the air temperature are basically consistent, which is sensitive to lower temperature. When the temperature sharply decreased, the temperature stress in the downstream zone is mainly in tensile stress state. The calculated results are basically consistent with the measured results, and the temperature stress induced by the day‐night temperature difference is the important reason for the horizontal cracks on the downstream surface. The submodel analysis method is an important alternative approach to study the changing laws of temperature field of arch dam. The research results not only provide an evidence for temperature control and crack prevention of Xiaowan arch dam but also provide a reference for temperature field simulation of similar projects.

Numerical simulation is an important method for analyzing the behavior of supports under complex geological conditions. FLAC3D, a widely used analysis tool, assumes the anchor structural unit to be an ideal elastoplastic material, which limits its ability to simulate strength decay in situations involving large deformation. In this study, we enhanced the anchor structural unit in FLAC3D software by developing a nonlinear convergent model of the anchor structure. This modification improved the simulation accuracy of anchor behavior in real-world engineering scenarios. The new model was verified through careful numerical pullout tests. In the numerical pullout tests, the predicted engineering conditions, including the deformation, axial force, and failure conditions of the Poisson’s ratio (PR) and negative Poisson’s ratio (NPR) anchors corresponded to the actual conditions in both the elastic and plastic stages. The model was then applied to compare the stress distributions in the surrounding rock during back mining using the conventional 121 method and the 110 method. The peak stresses were generally higher for the 121 method compared with the 110 method. The shear stresses of the two methods differed by 2.48 times in the XZ direction and by 6.41 times in the YZ direction, while the vertical stress differed by 1.3 times. For the rock mass outside the roadway, the shear stresses differed by up to 6.7 times in the XZ direction and by up to 3.5 times in YZ direction, while the vertical stress differed by up to 1.88 times. These findings confirm the advantages of the 110 method and demonstrate the key role of NPR anchors in improving the stress distribution of the surrounding rock. This research provides a reliable strategy for the large-scale numerical simulation of NPR and PR anchors.

A “random-type” sand–concrete interface shear test was developed based on the sand cone method, with a focus on the most commonly encountered triangular contact surface morphology. A “regular-type” triangular interface, matched in roughness to the “random-type”, was meticulously designed. This “regular-type” interface features five distinct triangular groove inclinations: 18°, 33°, 50°, 70°, and 90°. A series of sand–concrete interface direct shear tests were conducted under consistent compaction conditions to investigate the impact of varying compaction densities and triangular groove inclinations on the shear strength at the interface. Particle flow simulations were utilized to examine the morphology of the shear band and the characteristics of particle migration influenced by the triangular contact surface. This analysis is aimed at elucidating the influence of the inclination of the triangular groove on the shear failure mechanism at the sand–concrete interface. The findings indicate that: (1) The morphology of the interface significantly impacts the shear strength of the sand–concrete interface, while the shape of the stress-displacement curve experiences minimal alteration. (2) At smaller inclination angles, particle contact forces are arranged in a wave-like configuration around the sawtooth tip, resulting in a non-uniform stress distribution along the sawtooth slope. However, as the inclination angle grows, the stress concentration at the sawtooth tip diminishes, and the stress distribution across the sawtooth slope becomes more consistent. (3) Particle migration is significantly influenced by the sawtooth’s inclination angle. At lower angles, particles climb the structure’s tip through sliding and rolling. As the angle increases, particle motion shifts to shear, accompanied by a transition in friction from surface friction to internal shear friction. This leads to the formation of a wider shear band and an increase in shear strength.

The effects of sand grain size and interface groove spacing on the shear behavior of the sand-concrete interface were investigated under consistent roughness conditions through a series of interface shear tests. Tests utilized different grain sizes of sand and concrete slabs with varying surface textures, based on the sand pouring method. The results were compared with those of pure sand shear tests to evaluate variation characteristics in parameters such as shear stress and friction angle in the interface shear tests. Additionally, the particle flow model was employed to comprehensively analyze rotation characteristics of sand particles and the development trend of shear band width. The findings indicate that: (1) interface shear strength is closely linked to grain size distribution range and groove spacing; (2) thickness of the shear band is positively correlated with particle size, while its correlation with groove spacing is weaker.