Study On The Evaluation Of Stability And The Support Strategy Of Zhang Zhuo Expressway’s Tunnel Surrounding Rock

In recent years, along with the increasing difficulty of engineering construction, the problem of deformation and destruction of tunnel surrounding rock under complex geological structure and conditions are becoming more and more outstanding. Thus, it is of particular importance to study the characteristics of rock mass structure and deformation mechanism of tunnel surrounding rock and to put forward corresponding supporting strategies.Through analysis of analyzing characters of structural geology background and engineering geological petrofabric in tunnel constructing area, the paper divides it into four categories: tectonic rock formation, clastic rock formation, metamorphic rock formation and magmatic rock formation. Besides, according to formation lithology, features of structure plane and rock mechanics parameters, rock mass structure of tunnel can be separated into blocks, laminar structure, fragmentation as well as bulk solid. This paper researches the method of tunnel surrounding rock classification that based on distance discriminant analysis, the dissertation discusses ensemble classifications of tunnel surrounding rock and selects five parameter indexes including rock quality designation, index of biotic integrity, uniaxial compression strength of saturated rock, coefficient of elastic resistance and groundwater status. After that, the classification model of distance discriminant analysis is set up. Then results of discriminant analysis of surrounding rock classification are reached.By means of geological survey, borehole coring, indoor rock testing, etc., and on the foundation of comprehensive evaluation, test data are converted into parameter values of rock mass of tunnel surrounding rock through applying the method of comprehensive evaluation which is based upon Hoek-Brown’s failure criterion, testing technology of rock mass elastic wave is employed to back-calculate rock mass mechanical parameters. Hence, empirical numbers just like quasi-compression strength of rock mass, tensile strength, shear strength and modulus of deformation can be acquired. Furthermore, with the help of ABAQUS Adina system, and the imitation of dynamic procedures of excavating a tunnel, the paper analyzes the stress field that are at different levels, the displacement field, and features of plastic zone. Finally,support strategies of expressway’s tunnel surrounding rock based on characteristics of rock mass structures are put forward.