| Based on the biggest hydraulic engineering in the history of Gansu province-the first phase water supply of Yintao project in7#tunnel of the main canal as the research background. In view of the hydrological and machine of the tunnel surrounding rock, considering the change of the influence of rock porosity and permeability coefficient under the rock mass seepage state. Using the program ABAQUS of the large-scale non-linear finite element analyses the surrounding rock distribution and variation range of deformation, pore pressure, stress, strain and plastic zone under the condition of different depth and different excavation distance. To deepen understanding of the deformation characteristics of surrounding rock, rock mass damage and strength characteristics. Supporting science and technology support in the line selection, the excavation and supporting design of the construction for the tunnel, strengthen the response capacity of the tunnel disaster prediction and disaster prevention and mitigation. It is significance ensure the safety of engineering and normal construction and save investment.This paper has the main achievements and conclusions as follows:1、Through the comprehensive analysis of the engineering investigation datum and the results of scientific research of the Yintao project and the7#tunnel of surrounding rock engineering geological conditions of supplementary survey accumulated over the last decades. Based on the existing research achievements, the regional geological environment, topography and geomorphology, neotectonics, formation lithology and geotechnical parameters of Yintao project are analyzed and evaluated with the theoretical guidance of tectonic theory and geological system theory. And reaching every parameter of the applicable model analysis and calculation.2、This paper analyzes the seepage characteristics of fractured rock mass, coupling hydro-mechanical equation and the coupling relationship between of them, summarizes the coupling hydro-mechanical model that widely used at present. In this paper, based on the effective stress principle, considering permeability coefficient of the fractured rock mass, under condition of the surrounding rock coupling elastic-plastic stress. The coupling model of seepage and stress rock masses of large elastoplastic deformation are established by using updated Lagrangian method. The geotechnical materials using Mohr-Coulomb model and the lining structure materials using linear elastic constitutive model for analysis.3、The damage forms of tunnel structure, mechanical characteristics and the mechanical properties are summarized analysis, discusses the role of support structure system of surrounding rock, summarizes the mechanism of action about shotcrete, radial anchor, steel arch shelf support and steel mesh in detail when using new Austrian method on construction of primary support. Provide theoretical basis for that using the method of drilling and blasting excavation and the construction of New Austrian Tunneling Method on local district which hydrous unconsolidated sandstone.4、Using the ABAQUS nonlinear finite element program to simulated analysis distribution and variation range of deformation, pore pressure, stress, strain and plastic zone of tunnel surrounding rock which respective to embedded depth in the100m、150m、 and170m and excavation distance of10m、15m、20m、25m and30m of the7#tunnel. It is concluded that the deformation of surrounding rock with the actual monitoring get basically the same to provide technical reference for construction of the tunnel excavation.5、Combining with the engineering geological problems in TBM construction will be large deformation and sudden water inflow depending on statistical analysis of engineering geological problems occurred in TBM constructions of the soft rock7#tunnel. The research result provide concrete prevention and disposal measures, make the TBM smooth quickly through the soft rock area and provides effective methods and suggestions for the similar engineering problems.6、This article summarizes the1#tunnel in hydrous unconsolidated sandstone extremely bad geological location determine the freezing method which is the world’s most advanced construction scheme that include tunnel drilling, setting horizontal hole, nearly horizontal hole soil freezing temporary reinforcement and the mining method of underground building. This paper describe the main construction sequence, the principle of freezing construction, the main technical points, the basic approach control of frost-heaving and thaw-settlement and the informationization construction monitoring. |
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