Research On The Method For Judging The Stability Of Tunnel Surrounding Rock According To Numerical Simulation And Construction Monitoring

With the development of the science and technique, communications and transportation, water conservancy, the city underground traffic and utilization underground space, etc, especially the rapidly development of freeway construction in recent years in our country, put forward the higher request to the tunnel engineering on the quality. The large-scale underground engineering construction has promoted the building technology of tunnel. And a great deal of bolting-shotcreting practices and the new achievements of rock mechanics have established the modern support theories, more valid construction method based on the thought of New Austrian Tunneling Method(NATM) has appeared. A basic demand of this method is to choose the reasonable parameters and construction time of secondary lining according to judging the stability of tunnel surrounding rock with the monitoring data. For seeing out the thought of the NATM and economizing project cost, it is very important to judge the stability of tunnel surrounding rock in the construction procedures.Relying on the yinjiayan tunnel project, the tunnel situated on the freeway of Hu (Shanghai) -Rong (Chengdu) in Heibei province, this paper puts the emphases on analyzing the stability of tunnel surrounding rock with numerical simulation and construction monitoring. The means of research to be adopted in this paper mainly is as follows:1. Utilizing the structure analysis software ANSYS7.0 to imitate the course of tunnel's excavating, which is of great benefit to search for the sensitive point on the section of stability test.2. Testing tunnel surrounding rock's strain with Fiber-Grating Gauge, and according to some knowledge of the theory of elasticity to calculate out the clearance displacement of tunnel.3. Based on gray system, programming the software, which can be used to forecast the final clearance displacement of tunnel according to some data of monitoring, named GM-TUNNEL.4. According to Technical Specifications for Construction of Highway Tunnel (JTJ042-94), it is effectual to judge stability of tunnel surrounding rock with the clearance displacement and final clearance displacement of tunnel that have been calculated out previously.This engineering practice has showed that the above method is simple and feasible, the result are reliable. All methods and programs adopted in this paper can be used to the other multi-arch tunnels. Especially, the method, combining gray theory for forecast the tunnel final clearance displacement with the technology of tunnel surrounding rock strain test to judge the surrounding rock's stability put forward a new thinking and method for the similar tunnels.