Infrastructure projects on slopes that are exposed to changes in water levels face unique challenges. Fluctuations in water levels can significantly impact the stability and integrity of the slope. Stresses affecting soil nails are influenced by various factors, including changes in groundwater levels due to rainfall, temperature variations, or human activities. While studies have addressed the use of soil nails to enhance slope stability, there has been limited attention to the performance and serviceability of soil nails under cyclic changes in the groundwater table. Lateritic slopes are susceptible to instability due to factors such as extensive weathering, inadequate drainage, and steep cuts. Erosion and slope failure are exacerbated by insufficient vegetation cover, climate-induced degradation, and human activities. This highlights the importance of understanding the stress generated and the interaction between the soil and reinforcing material. In this study, centrifuge modelling was employed to simulate cyclic saturation and desaturation of a lateritic slope in response to fluctuations in groundwater levels. Four centrifuge tests were conducted on slopes with a 5V:1H ratio, both unreinforced and reinforced, at two different soil densities. The slopes were subjected to cycles of saturation and desaturation using a seepage simulator located behind them. Both unreinforced and reinforced slopes exhibited stability within a gravitational range from 1 to 40 g, showing no apparent cracks or settlements. Following the initiation of water flow through the slope, a gradual flow slide failure occurred in the unreinforced slope. When exposed to fluctuating water levels, the utilization of soil nails prevented the development of a continuous slip plane in higher-density slopes, while lower-density modelling revealed a failure slump and tensile cracks on the slope surface. Increased excess pore water pressure during ground saturation reduced effective stress on soil nails, reducing their tensile resistance. Conversely, lowering groundwater levels increased effective stress, mobilizing axial forces in the nails. This cyclic variation caused visible changes in settlements, strains, and tensile cracks in the slope following saturation and desaturation cycles.

This study investigated an effective protection strategy for the intermediate period of the bioprotection technique using the jute rope grid. This paper presents the results and interpretation of the experimental study of a model river bank subjected to failure under sudden drawdown conditions and its response after protection with the jute rope grid under the geo-fluvial condition. The model bank was composed of silty clay soil collected from Parlalpur ferry ghat on the left bank of river Ganga, Malda district, West Bengal, India. In this experimental study model, the model river bank with a slope of 1 V:1.5H was prepared in the laboratory considering a linear scale of 1:25 to simulate a prototype river bank in the upper reach of river Ganga in West Bengal, India. The first series of experiments examined the impacts of maximum flood duration, moisture content, and drawdown on the shifting of failure location at the most damaged of the river bank. The second series of experiments were performed for the model river bank protected with a jute rope grid of various mesh grid areas. At critical geo-fluvial conditions, the effect of the jute rope grid having different mesh grid sizes was investigated to improve failure location and reduce settlement depth at the most damaged of the river. This study showed a reduction in the damaged area of the bank from 57.8 to 16.7% and 94.8% reduction of settlement employing the optimum jute mesh grid area of 6.25 cm2.

Suspended waterproof curtains combined with pumping wells are the primary method for controlling groundwater levels in foundation pits within soft soil areas. However, there is still a lack of a systematic approach to predict the groundwater drawdown within the foundation pit caused by the influence of these suspended curtains. In order to investigate the variation of groundwater level within the excavation during dewatering processes, the finite difference method is employed to analyze the seepage characteristics of foundation pits with suspended waterproof curtains. Basing on the concept of equivalent well, this study examines the coupled effects of aquifer anisotropy (ki), aquifer thickness (Mi), well screen length (li), and the depth of waterproof curtain embedment on the seepage field distortion. A characteristic curve is established for standard conditions, which exposes the blocking effect of the curtain on the amount of groundwater drawdown in the pit. Additionally, correction coefficients are proposed for non-standard conditions, which, in turn, results in a prediction formula with a wider range of applicability. Comparative analysis between the calculated predictions and the field observation data from an actual foundation pit project in Zhuhai City validates the feasibility of the quantitative prediction method proposed in this research, which also provides a 21% safety margin.