PRE-REINFORCED TECHNOLOGY FOR SHALLOW EXCAVATION TUNNEL IN SAND GROUND

This article is based on the project of Guan-Hui inter-city rail transit. It uses field experiment, laboratory model experiments and numerical simulation method and develops a pre-reinforced technology for shallow excavation tunnel crossing sand ground. In analysis of the deformation of surrounding rock and supporting system suitable pre-reinforced method, scope and parameters can be obtained. The conclusions are as follows:Curtain grouting in tunnel and surface grouting are difficult to form waterproof curtain. When crossing sand strata, horizontal jet grouting and tunnel face grouting are the best pre-reinforcement scheme. Increasing grouting range is disadvantageous to control vault subsidence and horizontal convergence in sand strata, but can strengthen the integrity of the surrounding rock in unsand strata. Meanwhile, it is favourable to control the subsidence of ground. Changing the reinforced area parameter is highly advantageous to control the settlement of tunnel vault in sand strata. The better grouting quality accomplished, the greater the self-supporting capability of surrounding rock improved, while the horizontal displacement is nearly unchanged.