Comprehensive Monitoring and Analysis of Segment Cracking in Shield Tunnels
1 Shaanxi Provincial Major Laboratory for Highway Bridge & Tunnel, Chang'an University 2 Urban Railway Company, China Railway Electrification Bureau Group 3 Geophysical Testing Center, China Railway First Group Co., Ltd 4 Zhengzhou XingGang Investment & Development Group Co., Ltd 5 School of Highway, Chang'an University
Abstract：
Segment defects like cracking, damage and dislocation have extremely adverse effects on shield tunnels. Using the water inflow event of a shield tunnel on the Xi'an metro as an example, this paper analyzes the situations and relevant causes of segment defects by utilizing field surveys, GPR detection, ultrasonic crack detection, displacement measurement, etc. The results show that: 1) the damages occurred on the segment at an early stage due to the cavities formed around the segment ring and the irregularly distributed loads upon it; 2) the displacements occurred on the segment because of additional asymmetric loading caused by grouting pressure, the cumulative lateral displacement of which was 3.4 cm with the upward movement reaching 5.5 cm at the end of grouting; and 3) the maximum depth of segment crack was 134.9 mm and its maximum width was 1.0 mm.
2015, Vol. 52 