Model Test of TBM Tunnel Crossing Large Dip Angle Fault Zone under High In Situ Stress

Abstract

In order to study the effect of fracture zone on tunnel stability under high ground stress and to reveal the disaster mechanism of fracture zone surrounding rock compressor, the TBM tunnel of Fragrant Furnace Mountain Tunnel in the F12 fracture zone in Dali I section of central Yunnan was experimentally studied. The results show that the TBM cutter head has a significant effect on the surrounding rock pressure in the range of 0.43 D~0.5 D (hole diameter), with a maximum increase of 1.19-fold. As the measurement point approaches the tunnel contour, the displacement of surrounding rock increases. As TBM traverses the fracture zone interface, the displacement of surrounding rock increases at the maximum rate. The effect of TBM shear rock formation failure on the internal displacement of rock formation is 1.21 D in the front and not more than 1.5 D in the top. Sliding and loosening of the fault zone looser above the interface can easily lead to blockage of the fault zone, and the pressure of the surrounding rocks at front edge does not affect more than 1.73 H (the length of horizontal projection of the fault zone interface). Therefore, in the course of construction, the interface of fracture zone should be promoted to reduce the construction risks.