Extensive numerical and experimental studies have been conducted to investigate the behavior of soft ground improved with geosynthetic-encased stone columns (ESCs). However, almost no studies have been performed to evaluate the use of ESC in mitigating the liquefaction hazard of saturated sand strata. For this purpose, three-dimensional nonlinear finite element (FE) analyses using the open-source computational platform OpenSees was performed to evaluate the mitigation of mildly sloping saturated cohesionless strata improved with the ESCs. A systematic parametric study was conducted to investigate the potential influence of geosynthetic/encasement length (L_enc), soft clay interlayer, and ground motion characteristics on improved efficiency. ESC remediation in various types of sand strata is also addressed. In addition, the effect of ground slope angle on the deployed remediation is discussed. Generally, ESC remediation was observed to be effective in reducing lateral deformation of the sand strata. It was found that improved efficiency also seemed to be definitely influenced by the geosynthetic/encasement length L_enc, the various types of sand strata, the thickness of the soft clay interlayers, and ground motion characteristics. Overall, ESC remediation may be used to achieve a reliable solution through the provided approaches.

For rigorous understanding the shallow landslide mechanisms and deformation characteristics of expansive soil slopes, a comprehensive in-situ monitoring platform is established. Triaxial creep tests and microstructure analysis with scanning electron microscopy are also conducted on expansive soil samples obtained from Binxi station. Field monitoring data indicates that freeze–thaw (F–T) cycle and snowmelt infiltration significantly increase the creep deformation of expansive soil slope during spring melting period. Due to the influence of F–T cycle and snowmelt infiltration, more soil grains are involved in the shear deformation contributing to a large, localized shearing. Additionally, the microstructural analysis shows that F–T cycle influences the relationship between expansive soil grains that gradually change from face–face contact to point–face contact or edge–edge contact form. The shallow landslide mechanisms of expansive soil slope are revealed from creep deformation and microstructure characteristics of soils after the F–T cycle and snowmelt infiltration, which can be summarized into two stages, namely, the snowfall accumulation state and snow melt-shallow infiltration stage. These results can serve as a good reference for the prevention of expansive soil slopes in seasonally frozen regions.

Reductions in bleeding rates and bulk shrinkage of grouting repair materials comprise the key to solving the leakage of earth–rock dams. In this paper, an anti-seepage grouting material for earth–rock dam was developed by introducing mineral admixtures and graphene oxide (GO) nano sheets into low-cost clay–cement grouting materials and by adding polycarboxylate superplasticizers (PCs) to improve slurry viscosity. The experimental results show that the shear stress and viscosity of the slurry increase with the increase in GO concentration, and the slurry has a certain thixotropy. GO can provide a platform to promote the formation of hydration products and fill the pores of clay particles due to its high specific surface area and low volume; in this paper, the microstructure of clay–cement–graphene oxide (CCGO) grouting materials were improved. Therefore, the bleeding rate, bulk shrinkage rate, setting time and unconfined compressive strength (UCS) of the sample were macroscopically improved. In particular, the bleeding rate and bulk shrinkage rate were shown to be 0% when the content of GO reached 1.08 g/kg. Thus, the grouting anti-seepage and reinforcement performance of CCGO grouting materials were improved.

In order to solve the special needs for the durability and resistance of concrete materials in power transmission projects in Northwest China. Using sodium silicate and bentonite as capsule core and ethyl cellulose as capsule wall, microcapsules were synthesized by physical method. Standard specimens of cement-based materials were prepared by adding graphene oxide as conductive medium. Indoor experiments and micro technology were used to determine the optimal ratio of graphene-microcapsules, study the effects of graphene content, microcapsule content, and curing age on compressive strength, resistance, and self-repairing effect of the composite material. The results show that the average size of microcapsules was about 1.25 mm. The microcapsule was a relatively regular sphere with rough surface and dense structure. The recommended content was 2% microcapsules and 0.1% graphene oxide. With the increase of microcapsules and graphene oxide, the compressive strength first increased and then decreased, and the resistance increased gradually. After the cracks were repaired, the repairing rate of compressive strength was 57% and the recovery rate was 81%.

Cutting slope failures occur frequently along the high-speed railways in Northeast China during the construction due to snowmelt infiltration. This study addresses this issue by applying a three-dimensional numerical model. The influence of the depth of accumulated snow (d_s), daily temperature variation (ΔT), and freeze-thaw (F-T) cycles on the seepage field and stability of cutting slopes is discussed. The results demonstrate that water seepage due to snowmelt infiltration primarily extends through the ground surface by about 10 m. The deep-seated instability is likely to occur under a prolonged and highly accumulated infiltration, while shallow failure is associated with intense, short-duration snowmelt infiltration. The maximum degree of saturation (S_r) and pore-water pressure (PWP) values are observed at the slope toe. Increasing d_s and ΔT increase the S_r and PWP due to snowmelt infiltration and thereby decreases cutting slope stability. Compared to the d_s and ΔT, the F-T cycle is more likely to cause slope failure. In addition, the F-T cycle also induces the reduction of soil strength and the crack propagation. Overall, the conducted study provided useful help toward the process of safer design for cutting slope along the high-speed railway in seasonally cold regions.