Study of Stability Numerical Simulation of a Limestone Slope Based on Ground-Penetrating Radar and Displacement Back Analysis

The overall dissolution and weathering of limestone slope have significant temporal and spatial variability, so it is difficult to obtain the mechanical parameters of complete slope accurately and effectively according to conventional specifications, and the reliability of the numerical simulation result would be weaken or even to be completely invalid, and it is difficult to provide effective reference information for field construction. Therefore, a method for obtaining the mechanical parameters of slope based on GPR and displacement back analysis is proposed. On the basis of a limestone slope in No. 2 section of Yizhou-Hechi expressway in Guangxi, the water-rich and crushing properties of the slope are detected by GPR, and the slope is divided into different graded units. Then, a displacement gauge is installed on the non-cavity unit block to measure the displacement value of the unit block, and the mechanical parameters such as elastic modulus, poison's ratio and cohesive force of different unit blocks are obtained by using BMP90 displacement back analysis method accordingly. The grid model of complete slope is established by using MIDAS-GTS finite element numerical simulation software, and the sliding displacement value of the slope is calculated by using the mechanical parameters of different unit blocks obtained by back analysis and the whole assignment of specification. In order to compare and verify the numerical simulation result of the sliding displacement value, the field synchronous monitoring and measurement of the displacement is carried out. Compared with the results of synchronous field displacement monitoring and measurement, it is found that the numerical simulation values based on slope unit division and its back analysis result are close to the monitored values, which indicates that the mechanical parameters obtained by this method are more consistent with the real values of slope than the mechanical parameters of complete slope generally assigned according to the specification. The study can provide relevant reference for numerical simulation analysis of limestone slope stability in dissolved areas.