| Pile-pile cap–one-wall support wall–connection beam and Pile–pile cap–two-wall support wall of treatment mode, which plays an important role in karst tunnel excavation. Stability study on treatment structure and surrounding rock in tunnel excavation, which was been as researched object in this paper, the deformation of treatment structure and surrounding rock were tested by installation of a serious of gauges.According to the onsite testing results to analyse the mechanical characteristics of treatment structure in tunnel excavation, A three-dimension element software (ansys) was utilized to simulate the the interaction between treatment structure and tunnel excavation,the displacement and stress analysis of treatment structure in tunnel excavation. Some advice about treatment structure design and construction were put forward by analyzing the field-test results, theoretical analysis results and numerical simulation results. The main research content of this paper as follows:1. According to a big karst cave in highway tunnel engineering of Qing-Lian Expressway in BaiXuGong, by site monitoring and analyzing the deformation of treatment structure by karst cave in highway tunnel , evaluation of safety reliability of treatment structure .The monitoring date and the experiences can be for reference in design and construction for the tunnel crossing a big karst cave, it is great significance to tunnel engineering and the safety operation.2. A three-dimension element software (ansys) was employed to simulate the interaction between tunnel excavation and treatment structure in Baixugong tunnel of number 1,the method is able to provide a better simulation to treatment structure in tunnel excavation. According to analysis of calculation results and measured data, the deformation characteristics of surrounding rock and support structures were analyzed and the pre-support effect of treatment structure in karst tunnels was evaluated.3. Based on the excavation of Baixugong tunnel, a numerical analysis concerning the influence of karst caves in the top,at the bottom,in laterral positive and in latrerral 45°of tunnel on deormation features of the surrounding rock masses is carried out by using two-dimension element software (ansys); The discussion of karst caves of different position,different sizes and different distance of tunnel on stability of the surrounding rock,and initial appearance unstable region in surrounding rock, some advice about karst tunnel construction were put forward;4. The deformation characteristics of treatment structure karst tunnel excavation was analyzed by field test, numerical simulation and the design and construction about treatment structure were discussed. Some advice about design and construction of treatment structure were put forward base on summarizing the existing experiences. |
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