Optimization Research On Back Analysis Of Displacement For Mechanical Parameters Of Granular Rock

For the designers, they should ensure the mechanical parameters of rock-soil body are close enough to the actual situation, so that the stability analysis of rock-soil body and supporting structure can be successfully used to guide the design and construction.A large number of constructions of tunnel engineering show that, to the positions of thefault deep buried in tunnel and its influence zone, the structure of shallow hurried section andhighly weathered zone, the deposit section on the tunnel and loose sandstone section, tunnelexcavation easily results in the instability and collapse of surrounding rock for destroying thebalance of dispersions. At present, there are many research results about determining the rockmechanical parameters. But the study on mechanical properties of dispersive surroundingrock is few. Therefore, it is very important to study the mechanical parameters of dispersivesurrounding rock in tunnel.Based on the transportation technology projects of Hunan Province-back analysis offailure mechanism and monitoring information of surrounding rock granular during highwaytunnel construction, the thesis conducts a study of determining mechanical parameters ofdispersive surrounding rock in tunnel entrance section k34+200～k34+250, relying onengineering practice of Duye tunnel in Jishou-Huaihua Highway. The main work andconclusions are as follows:（1）Based on analysis of engineering geology of dispersion rock of Ji Huai highwayDuYe tunnel and in which climate, hydrology factor, which showed a significant linearlithologic characteristics and mechanical parameters of rock mass is difficult to determine;summarizes and introduces the commonly used methods, the advantages and disadvantages ofthe rock mechanical parameters. Then it obtains the assessment theory of rock parametersbased on the Hoek-Brown failure criteria and that the displacement back analysis formechanical parameters of the complex geological rock has good application based on themonitoring techniques and numerical modeling.（2）It describes the development and application of the Hoek-Brown failure criterion; itstudies to determine its input parameters It found that the uniaxial compressive strengthσciwith point load strengthIs(50)has better linearity by point load tests for dispersion rock. thevalue of mechanical parameters of DuYe is estimated by using Hoek-Brown failurecriterion,the value is conservative and it is easy to impact by geological strength index GSI,ithas the maximum sensitivity. （3）Introduces the development and application of displacement back analysis;Considering the efficiency problem of the back analysis, the golden section method is adoptedto optimize a displacement back analysis; Reasonable to determine the displacement backanalysis of parameters; Du Ye Tunnel surrounding rock mechanics parameters are determinedby using displacement back analysis; the result is existence a question of uniqueness andeffectiveness.（4）For the above problems,it put forward a kind of new method that based on HoekBrown failure criteria and the combination of displacement back analysis to determine rockmass mechanics parameters, the new method is applied to engineering practice of dispersionrock of DuYe tunnel, it is considered verified the usefulness of by reverse speech and solvedto determine the validity and uniqueness of rock mass parameters.