| High temperature, high ground stress and complicated geological conditions, with severe weather conditions and other labels have always been the focus and difficult issues of tunnel construction in remote areas, especially in recent years, the rapid development of infrastructure in those areas forces us to face these problems, which needs to be solved imminently.Located in high altitude and cold regions, Gaoligong mountain dulongjiang highway tunnel has not only complex geological and severe weather conditions, but also is a tunnel with a total length of 6680 m, maximum depth about 990 m, which belongs to long and deep tunnel. High temperature and high stress are the key problems in the design and construction of the tunnel, under the Gaoligong mountain dulongjiang highway tunnel construction project, this paper analyzed the initial temperature field, initial stress field, and the influence of coupling action of temperature and stress to the surrounding rock in the tunnel excavation process.①In this paper, initial temperature field of the tunnel site has been analyzed and the initial temperature distribution has been gat. The distribution results of the tunnel site’s initial temperature showed that the variable temperature zone of the tunnel site is located about 30 m deep, and the variable temperature zone ranges between stake number K0+270 and K0+341 near tunnel inlet, between stake number K6+843 and K6+950 near outlet port. Before excavation, the maximum temperature of surrounding rock along the tunnel can be 18.93 degree and the minimum temperatures can be-4.63 degree.②In this paper, in-situ stress field of the tunnel site has been analyzed by using the method of site test and numerical simulation. The In-situ stress of tunnel stake number K1+585 and K6+003 have been tested by hollow inclusion stress-relief method and sound emission method. The site’s weight stress field distribution has been analyzed through the finite element software named Ansys. The compared results shows that most of the tunnel region’s horizontal stress is much bigger than the vertical stress, and the constructed stress took a large percentage in the whole in-situ stress.③Take the results of the tunnel site’s temperature field analysis and stress field analysis as border condition, this paper analyzed the temperature and stress coupled field in the excavation process, from the results we can see that the main effect of cold air to the tunnel surrounding rock’s temperature and stress lies within the range of one time section size of the tunnel, within which the tunnel surrounding rock’s temperature and stress changes most obviously in a strong nonlinear trend, while those with 2-3 times beyond the tunnel range basically converges to the initial temperature and initial in-situ stress of the surrounding rock. From the longitudinal impact point of view, the surrounding rock’s temperature and stress of the tunnel’s central part is affected most by cold air, which decreases to both ends. The maximum affected temperature of the surrounding rock is more than 13.5 degree, and its maximum effect on the minimum principal stress, intermediate principal stress and maximum principal stress is 3.30 MPa, 4.09 MPa, 1.74 MPa respectively.④Considering the actual engineering application, this paper also take yearly minimum temperatures as convection load temperature, then analyze the temperature and stress coupled field in the excavation process. According to the calculation results, we recommend that special attention should be paid to convection load temperature’s affect to the central part of surrounding rock’s stress, and we should also note that this affect is a relatively long time process, which needs long-term monitoring in construction process, even in the process of tunnel operation, the effect of temperature change to tunnel surrounding rock stress’ s change should be considered, so does the temperature influence to lining’s frost-heave stress. |
PDF Full Text Request