Study of the Subsidence Width Influence on the Geotextile Control of a Subgrade Collapse Based on a Half-Symmetric Model Test

The geotextile can be used to treat a subgrade collapse in karst areas. The subsidence width is an important factor affecting the geotextile to treat subgrade collapses. However, the available studies on the influence of the subsidence width on geotextile treatment settlement are limited. To study the effect of the subsidence width on the geotextile control of subgrade collapses, the half-symmetric model test had been established. To make up for the deficiencies of the model test, the optimized subsidence width was probed through a numerical calculation under ten different situations conducted by the finite element analyses. Previous full-section model test results were used to verify the rationality of the half-symmetric model and calibrate the input parameters of the numerical models. The influence of the subsidence width on soil pressure, tensile force and deformation of the geotextile, and soil settlement was analyzed. With the increase of the subsidence width, more loads of the subsidence area were transferred to a stable area via the geotextile, the vertical normal stress at the edge increased rapidly, the tensile force of the geotextile and vertical soil displacement in the subsidence area increased noticeably. When the anchorage ratio of L ≤ 2.0B, the geotextile fracture or soil failure occurred during the model test which indicated the geotextile treatment of the subgrade collapse was not suitable for projects with an anchorage ratio of L ≤ 2.0B. The geotextile might be reaching the limit of its tensile stiffness when the anchorage ratio of L = 2.22B. This is providing an insight into the treatment of a subgrade collapse in karst areas using geotextile.