Periphery trench for reducing the impact of surface subsidence on structures
Abstract
Tunnel excavations, underground mines and the collapse of abandoned shallow natural cavities induce a surface subsidence. The existing structures and infrastructures can be damaged by the strain and settlement of the soil in the subsided zone. Different strategies can be used to deal with the subsidence hazard before, during and after the subsidence occurrence. Some mitigation methods exist for reducing the impact of the subsidence on the existing structures. One of them is the periphery trench. The method consists in cutting the soil around the existing building then filling the trench with a compressible material. The effect of horizontal strain will be absorbed by the partial closure of the trench. Numerical methods (2D and 3D, finite element method and distinct element methods) are used to evaluate the optimal dimensions and the position of the periphery trench according to the magnitude of subsidence, the relative position of the settlement trough and the structure and the nature of the structure itself (mainly the position of the foundation). In addition, the numerical methods are used to determine the characteristics of the filling materials that can be recommended. A numerical parametric study has been carried out focussing mainly on the Young modulus of filling material. The numerical modelling results show clearly that the trench is efficient when the building is located on the compression zone of the subsidence. Moreover the distance between the trench and the foundation should be greater than one meter. The filling material must have a Young modulus ranging from 1 to 10 % of the Young modulus of soil.
Origin : Files produced by the author(s)
Loading...