Research On The Optimized Design Of The Excavation-mode And The Supporting-scheme On The Unfavorable Geology Tunnels Of The Shiziping Hydroelectric Station

The complex aeromechanical environment emerges in the diversion tunnel of the Shiziping hydroelectric station. Approximately eighty three meters segments of the several tunnels are mainly composed of incompact cracked stones and soil. Its structure is incompact unagglutinative and has badly punched conditions. It has difficulty determining its mechanics parameters and confirming the rationality of the temporary support measures.The estimate on the stability of the surrounding rocks of the unfavorable geology sections is the central techinique problem.The reasonable earlier support measure is the key guarantee to constuct successfully. The reasonable final support measure is the reliable guarantee that underground workshop can run securely and normally. Therefore, it is the base for the stability of wall rock and the optimization of support structure to reinforce the monitoring work as well as to lay stress to the analysis of information feedback in the construction period.This paper is on the base of practical project. It includes the analysis on the process of the excavation and the support measures. Based on the numerical analysis of the surrounding rocks and the settlement of the monitoring data,via contrasting,we fullfills the purpose to estimate the construction schemes and optimiazing the support parameters.On the side the dependability of numerical analysis is also validated.The main research efforts and concusions are as follows:(1) Depending on the characteristics of the surrounding rocks of the unfavorable geology sections, the kinds of adjacent rock and the support types and construction principles have been confirmed by using the hydraulic and water-electricity surrounding rock classification method.(2) According to the construction principles of the the unfavorable geology section,combining primary excavation methods of the tunnels,the actual effects of all kinds of excavation measures have been evaluated by gray relation analysis.Based on these analysis,the most excellent excavation measures are confirmed,as well as the idiographic excavation and support measures of the unfavorable geology sections are studied out.(3)According to the analysis of the monitoring data, the stability of the surrounding rocks of the unfavorable geology sections are estimated, moreover the initial designed construction technics measures and the support parameters before constructing are proved and amended.(4)Based on the finite element method theory, the process of the excavation and supporting of the tunnel of SZP project is simulated by the program system ANSYS. On the case of V classes rocks surrounding diversion tunnel in the CHUXIAN tunnel, this paper selects the typical geological section and establishes the simplified model geologically, and does the finite element numerical analogy on the choosing tunnel layout and estimates properly the deformation degree stability of the surrounding rocks and support measure adopting the two dimensional elastoplastic mohr-clulomb model. The excavating and supporting plan after amended is reasonable from the result of the data processing.(5) It brings forward the optimization results of the final support structure of the unfavorable geology sections by integrating the results of the numerical analysis and the monitoring data ,as well as the amended earlier support measures.