Study On Large Sections Small Spacing Tunnel Design And Construction Technology

In this paper, based on the the monitoring of the monitoring project of tunnel construction process, and then the data from the monitoring analysis and linear regression, to find out the inherent law of surrounding rock in the excavation deformation, the comprehensive physical and mechanical parameters of surrounding rock of tunnel invert, in order to carry out the research of tunnel construction project, the main contents are as follows.⑴ In this paper, combined with the theory of rock calculating mechanics and characteristics of field monitoring measurement, based on the typical cross-section tunnel observation point simulation data, starting from the quantitative evaluation method of the stability of tunnel surrounding rock, to study the stability of tunnel surrounding rock. In the situation of tunnel section under the different surrounding rock stress distribution, are not the same. Morphology of tunnel section five circles, the stress state is more close to the actual engineering of tunnel structure stress uniformity requirements in terms of its surrounding rock.⑵Based on the measured data of site monitoring, timely use of parameter inversion procedure to carry on the analysis, the equivalent mechanical parameters of surrounding rock of tunnel can be retrieved accurately, quickly and accurately, which can make a reasonable evaluation on stability of surrounding rock in tunnel construction, and the prediction of excavation tunnel on the stability of surrounding rock after excavation. Then the three-dimensional numerical model is established by use of physical and mechanical parameters of rock mass parameters obtained by calculation, comparison, large section and small spacing tunnel using three step and seven step excavation method of construction compared to the CD method of construction organization design is complex, the construction speed is too slow to reduce the construction cost, and wide popularization value and application prospect, provide the reference in the large section of domestic small spacing tunnel construction.⑶Through the numerical simulation to study the spacing in 10 m, 12 M, 15 m, 18 m, 20 m and other 5 kinds of working conditions of tunnel surrounding rock, a typical stress strain characteristics of the observation point, the large section tunnel with small spacing in the use of three step and seven step excavation method, the depth is 30 m, surrounding rock grade V case in this paper, and the terrain and geological conditions such as lots of similar tunnel, double hole spacing of 12 ~ 15 m range selection is more appropriate.⑷By numerical simulation of the tunnel face interval of 3M(0.25D), 6m(0.5D), 9m(0.75D), 12m(1.0D), 15m(1.25D) numerical simulation of five kinds of conditions, when the construction of the space of 12 M, the stability of tunnel surrounding rock is relatively poor, but in the safety control scope, there are also to shorten the construction period.