The Impact Study And Safety Assessment Of Nanshan Tunnel On The Tushan Lake Overpass Bridge

Since our founding, the economy is rapidly developing. At the same time, an irreconcilable conflict is produced by the surge in city traffic of car flow and passenger flow and the relatively small city space. In order to meet the requirements of driving speed, a lot of highway bridges and tunnels are needed in the design of urban expressway. Especially in the mountainous area, bridges and tunnels are very important for promoting the service level of urban expressway.This paper is based on the engineering support of Nanshan tunnel excavation and focuses on the following questions:â‘  when Nanshan tunnel across the watershed, the three-dimensional finite elem ent model was built of tunnels, caves and bridge piers to simulate the impacts on the o verlying piers which caused by the water pressure changes when excavationin a cave at the bottom of the pier internal. The results are compared with the measured values a nd standards to determine whether the water pressure is the main factor which influen ces the settlement of bridge piers, and further to determine whetherthe structure issafe.â‘¡ When during the construction blasting period of Nanshan tunnel, using the fi nite element simulation and experimental data to analysis the influence of the blasting on bridge pier column. The results are compared to the standards to assess whether th e structure is safe;Through the theoretical study and the analysis of a large number of valuable monitoring data of Nanshan tunnel, conclusions are as following aiming at different stages of tunnel design and construction:â‘  in the design phase, in the karst rich water area, it is required to distribute loads according to the most unfavorable factors. The experiment of releasing water pressure and the numerical simulation are also needed to determine the envelop line of the displacement on the original geological area when the water pressure decreases and to make sure the safety of the existing structures.â‘¡ when tunnel construction across the water, according to three meters deep of the smooth blasting, deep buried tunnel blasting vibration will not produce essential influence on the surface structures. So the structure is safe.