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Filters are critical components of hydraulic structures such as earth-rock dams and tailings dams, functioning to prevent soil particle loss and control phreatic levels. Clogging failure in filters can severely compromise the seepage stability of dam slopes. This study simulates the clogging process using a CFD-DEM fluid–solid coupling method, focusing on three key factors: sediment particle size, fine particle concentration in muddy water, and seepage pressure. The spatiotemporal evolution of void ratio, hydraulic conductivity, and dry density during clogging is systematically investigated. Key findings include: (1) Surface clogging occurs when the particle size ratio Ra (filter-to-sediment diameter ratio) is less than 2.2, while particle penetration dominates when Ra exceeds 8.8. Internal clogging emerges at intermediate Ra values (2.2–8.8), with numerical results showing strong agreement with empirical criteria and pore network modeling (PNM). (2) Higher Ra values enhance particle penetration, whereas lower values promote clogging. Increased sediment concentration accelerates clogging stabilization, while fluid pressure gradients exhibit negligible influence on clogging patterns. (3) Under internal clogging, the void ratio follows an exponential decay pattern over time and depth. These findings provide theoretical and technical support for optimizing filter design and construction in geotechnical engineering.

An experimental study of the failure behavior of sandstone specimens containing a single flaw under true triaxial compression was conducted. The main objective was to investigate the influences of the intermediate principal stress on the cracking pattern, stress–strain response, and acoustic emission (AE) activities. The results revealed that a higher intermediate principal stress resulted in higher specimen strength for constant minimum principal stress. The peak load of the test specimens generally increased with an increase in the flaw inclination angle. The crack initiation stress under true triaxial compression initially increased and then decreased with an increase in the intermediate principal stress at a constant minimum principal stress. The flawed specimens typically failed due to anti-wing cracks, regardless of the flaw inclination angle and the intermediate principal stress. The crack initiation angle was primarily determined by the flaw inclination angle. The rise time/maximum amplitude (RA) and the average frequency (AF) were used to identify the cracking type. The proportion of shear cracks was much higher than that of the tensile cracks during the cracking process. The proportion of shear cracks increased with the external load, whereas that of the tensile cracks decreased. The number of crack events decreased and then increased with an increase in the intermediate principal stress. A damage model that considered microscopic damage resulting from microcracks and macroscopic damage resulting from the pre-existing flaw was proposed to describe the failure behavior of rock specimens containing a single flaw under true triaxial compression.HighlightsThe influences of the intermediate principal stress on the failure behavior are discussed.The cracking mechanism for rock specimens under true triaxial compression is explored.A damage model that considered microscopic and macroscopic damage is proposed.

This paper develops a new method for calculating the passive earth pressure (PEP) on retaining walls under ultimate stress conditions. First, it is assumed that when the sliding wedge is in the limit equilibrium state, the soil elements on the slip surface, at the wall-soil interface, and within the wedge all reach the ultimate stress state obeying the Mohr–Coulomb criterion. The trajectory of principal stresses within the wedge takes the form of a circular arc. Subsequently, the PEP calculation equation for the retaining wall under ultimate stress conditions is derived based on the circular arc thin-layer unit method, with the unit obtained by layering along the principal stress trajectory. Furthermore, a formula for calculating the maximum friction angle ( δ max ) at the wall-soil interface is proposed under passive conditions. The influence of the wall-soil interface friction angle on the distribution form, magnitude, resultant force action point of PEP, and overturning moment at the base of the retaining wall is then analyzed. Additionally, the stress state of soil elements within the sliding wedge is determined according to the Mohr–Coulomb failure criterion. Finally, the proposed method was validated against numerical simulations and model test data. The PEP under ultimate stress conditions represents the plastic upper-bound solution, while Coulomb’s earth pressure serves as the plastic lower-bound solution, providing new insights for accurate assessment of PEP. The maximum wall-soil interface friction angle formulation established in this study offers a theoretical basis for determining the interface friction angle under passive conditions, particularly resolving the selection of interface friction angle when the backfill has a large internal friction angle ( φ  > 30°).

In valley regions where high-fill embankments are constructed, inadequate foundation bearing capacity is a frequently encountered challenge. At the Ankang Airport relocation site, expansive soils primarily originating from the Upper to Middle Pleistocene are widely distributed, which introduces substantial safety concerns for the stability of high-fill embankments. Prior to large-scale filling, a field experimental site was selected within the project area to conduct in-situ tests for ground improvement. Two ground reinforcement techniques—dynamic compaction and gravel pile compaction using driven casing—were implemented and assessed. Evaluations of physical and mechanical properties, including plate load and standard penetration tests (SPT), were carried out before and after the improvement procedures. Test results showed that the natural foundation soil had a characteristic bearing capacity of 260 kPa. Among the applied techniques, dynamic compaction replacement proved most effective, enhancing the bearing capacity to 580 kPa. However, due to the complex stratigraphy and shallow bedrock in certain zones, dynamic compaction may negatively impact bedrock stability. Numerical modeling further validated that dynamic compaction replacement induced the smallest settlement deformation. Targeted solutions were proposed in response to the issues identified during testing, offering practical guidance for similar foundation treatments in high-fill embankments over expansive soils.

High slope simulation analysis is an essential means of slope engineering design, construction, and operation management. It is necessary to master slope dynamics, ensure slope safety, analyze slope instability mechanisms, and carry out slope stability early warning and prediction. This paper, aiming at the landslide phenomenon of the high slope on the left bank of a reservoir project, considering the influence of stratum lithology, fault, excavation unloading, rainfall, and water storage, establishes a refined finite element model that reflects the internal structure of the slope. The fluid-solid coupling numerical simulation analysis of the high slope is carried out. Based on this, the failure mechanism of the slope under excavation unloading and heavy rainfall is explained. The application of an engineering example shows that under the combined action of excavation unloading and rainfall infiltration, the in-plane saturation of the structure formed at fault at the trailing edge of the excavation slope surface increases, the pore water pressure increases, and the shear strain concentration area appears at the internal structural surface of the slope. The shear strain concentration area extends along the structural surface to the front and rear edges of the slope, resulting in landslide damage.

The pumped storage power station (PSPS) is an important measure to achieve the strategic goal of “dual carbon”. As one of the preferred types for the upper reservoir dams of PSPSs, the concrete-faced rockfill dam (CFRD) often has a dam foundation on a steep transverse slop and is prone to produce slip deformation along the slope, resulting in poor anti-sliding stability of the dam slope. It is dangerous for the operation safety of PSPSs. Therefore, the slip deformation of CFRDs on dam foundations with large dip angles is investigated. The mechanism for the initiation of slip deformation is revealed. The design measures of physical mechanic and geometric structure are proposed to reduce slip deformation. The results show that the larger sliding forces and smaller anti-sliding forces are the fundamental reasons that CFRDs on dam foundations with large dip angles are prone to produce slip deformation. The larger the dip angle of the dam foundation, the larger the slip deformation of the dam body and face slab, and the smaller the safety factor of the dam slope. When the dip angle of the dam foundation is greater than 15°, the safety factor of the dam slope is less than the minimum value of 1.5 required by codes. The addition of pressure slopes can effectively reduce the slip deformation of the dam body or face slab and significantly improve the anti-sliding stability of the dam slope. When the height or width of the pressure slope platform is greater and the cohesion or internal friction angle of the pressure slope is larger, the slip deformations of the dam body and face slab are smaller, and the safety factor of the dam slope is greater. It is recommended that the height and width of the pressure slope platform be 1/2 times the maximum height of the main dam, and the density (cohesion and internal friction angle) of the pressure slope be equivalent to that of the main dam’s rockfill material. The research results can provide theoretical and technical support for the design and construction of CFRDs for the upper reservoir of PSPSs.

This study investigates the use of Ultra-High Molecular Weight Polyethylene (UHMWPE) fibers and fabric to enhance the flexural performance of Ultra-High-Performance Concrete (UHPC). A total of 45 specimens were tested to examine the effects of fiber type, fabric material, adhesive, and various combined strengthening techniques. The main findings are that incorporating UHMWPE fiber into the ultra-high-strength mortar (HSM) matrix provides superior performance compared to steel fiber, particularly in enhancing crack resistance and energy absorption. UHMWPE fiber-reinforced UHPC achieved a flexural toughness of 307 KJ/m3, over three times higher than that of steel fiber-reinforced UHPC (98 KJ/m3). The use of UHMWPE fabrics was more effective in improving the ductility and toughness of the composites than the use of glass fabrics. The bonding effect of using epoxy resin with UHMWPE fabric is better than using magnesium phosphate cement (MPC). Increasing the number of fabric layers improved the flexural properties of externally bonded fabric but had no impact on internal reinforcement techniques. The best strengthening method in this study was a combination of incorporating UHMWPE fiber internally and externally bonded fabric on a concrete surface, yielding the highest toughness of 580 KJ/m3.

Seepage flow is one of the primary factors that trigger slopes and landslides’ failure. In this study, the slope stability under saturated or unsaturated conditions is analyzed. The influence of a complex stress state on the slope stability with the saturated or unsaturated seepage flow is proposed in this paper. Firstly, an elastoplastic constituted model for the soil under a complex stress state is established and as a user subroutine of the finite element method code of FLAC. Secondly, the 2D and 3D problems of slope stability influenced by the saturated or unsaturated seepage flow are analyzed via the finite difference method with the influence of the complex stress state. Finally, the influence of the intermediate principal stress and the saturated or unsaturated seepage flow on the slope stability is analyzed in this study.

In order to study the compressive deformation and energy evolution characteristics of concrete under dynamic loading, impact compression tests with impact velocities of 5, 6, and 7 m/s were carried out on concrete samples with aggregate volume ratios of 0, 32%, 37%, and 42%, respectively, using a split Hopkinson pressure bar test apparatus. The broken concrete pieces after destruction were collected and arranged. The fractal characteristics of fragmentation distribution of concrete specimens with different aggregate rates under impact were discussed, and the roughness of the fragment surface was characterized by the fractal dimension of the broken fragment and the crack surface energy was calculated. In addition, the analytical equation of the fractal dimension of the broken fragment and the crack surface energy was established. The relationship between the specimen energy absorption and the crack surface energy was compared and analyzed. The results show that the concrete specimens are mainly tensile split failure modes under different impact speeds. The fractal dimension, absorption energy, and crack surface energy all increase with the increase in impact speed and decrease with the increase in the aggregate rate. When the aggregate rate is different, the effective utilization rate of the absorbed energy is the largest when the aggregate content is 37%. The surface energy of the crack can be used to estimate the concrete dynamic intensity.

To study the influence of consolidation stress ratio and stress history on 1-D consolidation permeability of saturated clay, one-dimensional consolidation permeability tests were carried out with GDS triaxial device. The results indicated that the permeability coefficient and void ratio of normally and overconsolidated saturated clay decreased with the increase of consolidation stress ratio under different consolidation stress ratios but the same stress history. And the amount of final sample’s compression increased with the increase of the consolidation stress ratio. Under the condition of the same consolidation stress ratio but different stress history, the amount of final compression of the overconsolidated saturated clay was smaller than that of the normally consolidated saturated clay. Besides, the stress difference σdv between consolidation pressure σ and gravity stress σcz was fitted to the amount of the final sample’s compression, and a good linear relationship between the stress difference σdv and the amount of the final sample’s compression under each consolidation pressure was obtained. The results showed that it is necessary to consider the influence of consolidation stress ratio and stress history simultaneously on 1-D consolidation permeability of saturated clay. Meanwhile, it can accurately predict the amount of the final sample’s compression after knowing the gravity stress. Moreover, a model prediction analysis was conducted on the saturated clay and recommended to use the modified Kozeny-Carman’s equation to predict the permeability coefficient of Luochuan saturated clay during one-dimensional consolidation.