Abstract When a metro running tunnel passes through an approaching bridgehead area of an existing expressway, it will increase uneven settlement of the bridge slope section and is liable to cause a serious vehicle bump at the bridgehead. Based on a running tunnel of Jinan metro line R1 underneath the existing Beijingjing-Fuzhou expressway bridge, the deformation law of an expressway bridgehead during shield tunnel construction is analyzed by a numerical model regarding the original reinforcement scheme, which only considers reducing the effects of shield construction on the pile foundation and ignores controlling the bridgehead deformation. The results show that adopting the construction sequences of the left line and then the right line is more favorable for reducing the deformation of the expressway bridgehead than the original reinforcement scheme, but it would cause 26.5 mm differential settlement at the bridgehead and can′t effectively prevent a vehicle bump at the bridgehead. In this context, a new technique is proposed that takes a cement mixing pile as an isolation pile and uses a deep concrete bridging slab to control bridgehead deformation. With this new technique, the maximum differential settlement at the bridgehead is 4.0 mm, the maximum longitudinal gradient variation is 0.4‰ and the maximum subgrade settlement is 6.5 mm, meet? ing the requirements specified.
Abstract：
When a metro running tunnel passes through an approaching bridgehead area of an existing expressway, it will increase uneven settlement of the bridge slope section and is liable to cause a serious vehicle bump at the bridgehead. Based on a running tunnel of Jinan metro line R1 underneath the existing Beijingjing-Fuzhou expressway bridge, the deformation law of an expressway bridgehead during shield tunnel construction is analyzed by a numerical model regarding the original reinforcement scheme, which only considers reducing the effects of shield construction on the pile foundation and ignores controlling the bridgehead deformation. The results show that adopting the construction sequences of the left line and then the right line is more favorable for reducing the deformation of the expressway bridgehead than the original reinforcement scheme, but it would cause 26.5 mm differential settlement at the bridgehead and can′t effectively prevent a vehicle bump at the bridgehead. In this context, a new technique is proposed that takes a cement mixing pile as an isolation pile and uses a deep concrete bridging slab to control bridgehead deformation. With this new technique, the maximum differential settlement at the bridgehead is 4.0 mm, the maximum longitudinal gradient variation is 0.4‰ and the maximum subgrade settlement is 6.5 mm, meet? ing the requirements specified.
.New Techniques for Bridgehead Deformation Control for Expressways Passed by Approaching Metro Running Tunnels[J] MODERN TUNNELLING TECHNOLOGY, 2017,V54(5): 217-223
2017, Vol. 54 