Geosynthetic-reinforced pile-supported (GRPS) embankment has been widely utilized in the railways and highways subgrade of soft clay area. The load transfer platform (LTP), consisting of sand layers and one or more layers of geosynthetic, is constantly used at the base of embankment to increase the load transfer to piles and reduce the differential settlement of embankment surface. However, the effect of different reinforced LTPs on the performances of GRPS embankment has not been fully understood. Eight centrifuge model tests were conducted to investigate the effect of five influence factors on deformation and load transfer of embankment, and tensile force of geogrid: placing geogrid or not, the number of geogrid layers, geogrid reinforced position, geogrid stiffness, wrapped-back geogrid setting in LTP. The results showed that the wrapped-back geogrid setting in the LTP was equivalent to anchoring the geogrid at the slope toe of embankment, which strengthened the reinforcement-soil interaction and restricted the pull-out displacement of geogrid to enhance the stiffness for LTP The LTP reinforced with stiffer geogrid or multi-layer geogrid contributed to increase the stability and load transfer of embankment due to the increase of the integrity stiffness for LTP. When the geogrid was set at the middle of LTP, the performances of the GRPS embankment was enhanced due to the more interfaces between the geogrid and soil to improve the integrity stiffness of the LTP. The two-layer geogrid reinforced in the LTP could be the best choice to enhance the performance of the GRPS embankment under the comprehensive consideration of the performance and economy. The five setting ways of the reinforcement in LTP increased the integrity stiffness of LTP, which provided more methods to enhance the performances of the GRPS embankment.

The use of a geotextile to treat subgrade subsidence after subsidence has occurred is investigated in this paper. To optimize the anchorage length and buried depth of the geotextile and evaluate the influences of the two factors on subgrade subsidence treatment, finite element analysis is performed and validated with existing model tests. The soil pressure, displacement, tensile force and deformation of the geotextile are studied. The results showed that the geotextile prevented an upward development of subsidence and stabilized the upper soil. The increase of the anchorage length of the geotextile transferred greater soil pressure from the subsidence to a stable area, induced a greater tensile force in the geotextile, and resulted in less soil displacement. As the anchorage length of the geotextile increased from 375 mm to 1500 mm, the surface settlement was effectively reduced from 1.05% to 34.18% when comparing to the situation without a geotextile. As the buried depth of the geotextile increased from 2 m to 6 m, the percentage of surface settlement was effectively reduced from 29.14% to 65.91% when comparing with the settlement corresponding to a buried depth of 2 m. It is suggested that the anchorage length of a geotextile should be the length of the subsidence with respect to width and that the buried depth of the geotextile should be 3–4 m for subsidence treatment. This provides insight into the treatment of sinkholes using geosynthetic approaches in karst areas.

The rigid pile composite foundation method is the most commonly used method for strengthening weak soil foundations. In this method, piles usually need to pass through weak soil layers, and the pile end falls on a bearing layer with good bearing capacity. Under existing technical conditions, the thicker the weak soil layer, the longer the pile body, and the more difficult it is to ensure the construction quality of the pile. In response to this issue, some scholars have adopted the rigid pile composite foundation method with a thick cushion layer for reinforcement treatment. This article uses PLAXIS 3D (V20.04.00.790) software to establish a finite element model of rigid pile composite foundation with a thick cushion layer and simulate the process of foundation reinforcement. The influence of parameters such as thickness, compression modulus, and shear strength index of the cushion layer on foundation settlement and pile–soil stress distribution is studied, and the reasonable range of these parameters is analyzed under the condition of considering reinforcement effect. Through comparative analysis, it can be concluded that for deep and weak soil areas, the thickness of the cushion layer can range from 0.5 to 2.6. The thickness and compressive modulus of the cushion layer have a significant impact on the settlement of the foundation, the pile–soil stress ratio, and the stress of the pile body, while the shear strength index of the cushion layer has a relatively small impact on these parameters. Reasonably selecting the geometric and mechanical parameters of the cushion layer can effectively reduce stress concentration at the pile top and better play the role of the soil between piles.

A new in-soil tensile test apparatus was developed to simulate the in-soil stress condition of geosynthetics in a real working state. An in-soil tensile test with or without friction was conducted, along with in-air tensile tests of eight types of geosynthetics, to evaluate tensile properties, including tensile load and secant tensile stiffness under different confining stresses using various methods. Under confinement, the tensile properties of geosynthetics increased with growing confinement, which were greater than those for the in-air tensile test, and the tensile properties were similar for tests with or without friction. The tensile load improvement factors F_T−σ and f_T−σ were introduced to quantify the confinement and reinforcement–soil friction differences between different tests, and the improvement ratios γ₁ and γ₂ were proposed to quantify the improvement of tensile load under confinement for the test with and without friction, respectively. Two formulas were proposed to predict the confined tensile properties of geosynthetics. The results showed that confinement was the major factor that improved the tensile properties of geosynthetics compared to reinforcement–soil friction. When the improvement ratio is not less than 1.5, the confined tensile load should replace the in-air tensile load with the tensile strength design of geosynthetics, which provides an insight into the design of reinforced soil structures.

In deep roadway mining, high water pressure causes rock mass cracking and weakens the overall strength, affecting the stability of underground metal mine mining roadways. Therefore, using a numerical simulation method, we analyzed the strain softening characteristics of rocks after the inflexion point of elasticity and studied the strain distribution and the minimum support resistance under high‐pressure groundwater conditions. Considering the groundwater pressure and effective porosity on the strain softening characteristics of the surrounding rocks, we investigated the critical groundwater pressure under which the surrounding rocks would remain stable. Actual engineering verification helps to obtain the supporting characteristic curves under different influencing factors. We found that water pressure and effective porosity are the significant factors that decide the development scope of the plastic zone. The more significant the increase of the plastic zone, the more notable the changes in the support curve. Moreover, the plastic zone is likely to occur when the hydraulic head is between 30 and 50 m; when the hydraulic head exceeds 50 m, it is likely to produce a relaxation zone.

To investigate the pitting evolution behavior of carbon steel in industrial–coastal atmospheric environments, a multiphysics numerical model was established by coupling tertiary current distribution, mass transport, and deforming geometry based on electrochemical corrosion mechanisms. Based on this framework, the effects of pH, salt concentration, and relative humidity (RH) on the pitting corrosion rate were systematically analyzed, and a predictive model for the pitting rate was subsequently developed. The results indicate that the pitting morphology gradually evolves from an initial conical shape to a hemispherical morphology and eventually develops into a quasi-cylindrical form. When the pH value increases from 6.0 to 7.0, the pitting rate decreases significantly, with a maximum reduction of 23.96%. Within the salt concentration range of 0.5%–1% (mass fraction), increasing salt concentration markedly accelerates the pitting process, resulting in a maximum increase in the pitting rate of 10%. In addition, the pitting rate exhibits a pronounced peak within the RH range of 72%–77%. The corrosion rates predicted by the proposed model are in good agreement with the experimental results, with relative errors within 5%. These results indicate that the numerical model and prediction formula established in the present study can reasonably predict the pitting evolution behavior and corrosion rate of carbon steel.