Settlement and Landslide Risk Analysis of Temporary Soil Dump Based on InSAR and Continuous Medium Model

The planned soil dumping in Shenzhen has been insufficient for a long time, and improper disposal of excess soil would pose significant safety hazards such as soil settlement and landslides. Therefore, analyzing the causes and potential impacts of soil dumping disasters is crucial for effective risk prevention and control. Interferometry Synthetic Aperture Radar (InSAR) is an effective land surface deformation monitoring technology with unique advantages, including low costs, large-scale implementation potential, and a high coherence level in the settlement analysis of soil dumps without vegetation.

This study investigated a soil dump with the highest risk potential in the Shenzhen-Shanwei Special Cooperation Zone, processing 91 Sentinel-1 images from 2019 to 2022 for deformation monitoring. An improved Small Baseline Subset-InSAR (SBAS-InSAR) method was utilized to analyze the soil dump’s time-series deformation, and multi-source remote sensing data were used for auxiliary interpretation. The experimental results indicate that rainfall, high temperature, and construction vibrations may cause instability of the soil dump. When the monthly rainfall is 200 mm/month and the temperature is 30℃, the meteorological conditions significantly impact the soil dump’s stability. In addition, vegetation and drainage procedures can help resist the impact of high temperatures and rainfall. Activities such as slope excavation, earthwork filling, and gravel production are also the main causes of settlement fluctuation in the soil yard. However, with artificial excavation, unloading, and comprehensive management, the soil dump’s LOS velocity decreases by 10% to 45%.

The Chishi soil dump remains stable during the original period and does not show a subsidence trend until the soil dump is formed. The overall settlement rate is around -33.3mm/yr, and most severe settlement occurs near the north slope with a maximum deformation rate of about -51mm/yr. The closer to the landfill’s center, the greater the soil thickness and the more severe the settlement. Moreover, with similar soil thicknesses, the settlement rate on the slope is higher than that at the top of the soil dump.

The limit equilibrium analysis of the soil dump indicates a risk of instability under continuous heavy rainfall. Therefore, a depth-integrated continuous medium model was introduced to simulate the surface process and analyze the potential landslide risk. The landslide simulation results demonstrate that a landslide will likely occur, harm personnel, and damage the buildings on the north side of the soil dump when it is saturated (≥ 0.50). This research can provide case references for the analysis, interpretation, disaster prevention, and control evaluation of similar soil dumps.