Analysis And Evaluation On Surrounding Rock Of Dabashan Tunnel

In recent years, with the rapid development of the expressway and highway of our country, highway tunnel has entered the new period of great development, which promotes higher requestion to build technology of highway tunnel, especially the long or big section highway tunnel.In the course of the expressway tunnel's construction, the stress in rock mass will redistribute around grotto. When this kind stress exceeds surrounding rock ultimate strength, surrounding rock will lose its stability and destruct. Stability analysis of surrounding rock is a momentous science research correlated with the expressway tunnel's construction. Particularly in the western mountainous areas with complx geological conditions, because of the diference of the influeneing factors and weight of it, to establish the methods system and analysis the evaluation result must be researched specially.Associated with the project of Dabashan tunnels, which is part of the Arongqi to Beihai highway, sticking to the evaluation of surrounding rock's stability and direct highway tunnel's construction, with the combination of qualitative evaluation, quantitative evaluation, integrate and local evaluation, the surrounding rock's stability of tunnels is studied systematically.Firstly, with the engineering geological factors influencing surrounding rock's stability of tunnel, the paper carries on the analysis and discussion about deformation and destruction mechanism to surrouding rock.According to structural surface development and elastic-plastic geological characteristics, intensity-tress control type is put forward. And the top arch is the weak point.Secondly, according to the specific engineering geological conditions of Dabashan tunnel, using surrounding rock classification, monitoring measurement, to evaluate the stability of tunnel surrounding rock. The classification is divided into three types: III surrounding rock, IV surrounding rock and V surrounding rock. Finally, based on the analysis of the basic theory about the interaction mechanism of the surrounding rock in construction, a numerical computation method with 2-D elastic-plastic finite element is proposed to analyze stability and safety of the IV surrounding rock in construction, through analyzing the distributing law of displacement. Dispelled the danger in construction process in order to prevent before the occur, and has significance in guiding the design and construction of tunnel.