Highway Tunnel Surrounding Rock Stability

In the course of the expressway tunnel's construction, the stress in rock mass will redistribute around grotto.When this kind stress exceeds wall rock's ultimate strength, wall rock will lose its stability and destruct. Consequently, the evaluation of wall rock's stability is a momentous science research correlated with expressway's roading.According to the data relevant to tunnel Manxie 3, one of Simao-Xiaomengyang expressway tunnels, this paper sticks to the evaluation of wall rock's stability of road tunnel in order to uphold wall rock's inherent stability and direct expressway tunnel's construction. With the combination of qualitative evaluation, quantitative evaluation, integrate and local evaluation, the author studies the wall rock's stability of road tunnel systematically.Firstly, starting with the engineering geological factors influencing wall rock's stability of road tunnel, the paper carries on the analysis and discussion about deformation and destruction mechanism to wall rock. According to thin intermediate layer and structural plane's well development as well as plastic characteristic to rock mass, the author puts forward intensity-stress type in rock mass which is the main deformation and destruction mechanism, whose destructing manners mainly involve to split slump and peel off.Secondly, aiming at the current "fuzzy question" in the wall rock's classification, the author introduces the fuzzy information analysis model and divides the criteria for classification of expressway tunnel's wall rock, establishing expressway tunnel's wall rock categorized model and quantitatively classifying the categories of the wall rock of tunnel Manxie 3.In addition, through dynamic numerical simulation of tunnel's construction, the author analyses the distributing law of stress and strain in rock mass followed with tunnel's construction, pointing out that the top and bottom of partition wall as well as the foot of sidewall should be monitored and upholded. Furthermore, the middle of partition wall should be focally fortified especially when partial stress occurs.Finally,using graphic method and the theory of block to carry on geometry analysis,differentiation of collapse and slipping and stability coefficient's calculation of unstable block body of regular tetrahedron form, the author draws a conclusion that direct collapse is the main style of losing stability and destruction of unstable block body in the wall rock of tunnel Manxie 3.