Detection accuracy analysis of TSP and its application in a river-crossing tunnel construction

Aiming at the problems of TSP such as long detection time and strong experience-depending, in order to improve the accuracy and the efficiency of TSP detection, we analyzed the key factors which affect data acquisition and processing accuracy of TSP and summarized the experiences of improving the detection efficiency of TSP. In combination with the TSP advanced geological prediction work in a river-crossing tunnel for water distribution project in Qiandaohu lake, the TSP tracing prediction or GPR detection in the area where the TSP resolution decreases were carried out and the geophysical abnormal area was verified by drilling. The results show that in the section with poor integrity of rock mass the values of longitudinal wave velocity, density and various mechanics modulus were low, TSP was sensitive to the detection of fracture zone but its identification ability of bedrock fracture water was relatively weak, the rock mass in the area where both longitudinal wave and shear wave velocities were lower had higher water-bearing probability, the GPR anomaly in the section of fractured water-bearing rock mass was characterized by strong reflection amplitude, event dislocation and lower dominant frequency. In the comprehensive prediction results, the advantages of various detection methods were complementary to each other, which provides important reference for the optimization of tunnel support and advance grouting scheme.