Study On The Unloading Mechanical Effect And Deformation Mechanism Of The Surrounding Rock Of Tunnel

In recent years more and more widespread use of underground space, a large number of city subway, highway tunnels and hydroelectric engineering in the construction process, have exposed the problem of rock during excavation unloading relaxation and deformation control difficult. To solve this problem you first need to solve to explore rock excavation unloading effect, and therefore the mechanical effects of unloading and deformation mechanism of rock has become a hot area of current rock mechanics and engineering applications.In this paper, a circular tunnel, for example, to study the mechanical effects of unloading and for the surrounding rock deformation mechanism. Kinetic theory of elastic mechanics build unloading rock tunnel effect model, based on the Laplace transform and residue theorem mechanical effects of unloading solve the model obtained after unloading tunnel surrounding rock stress and displacement analytical expressions.Jinping Ⅱ hydropower station on the 3rd tunnel as an example,The use of surrounding rock unloading mechanical effects model to calculate analysis, the mechanical effects of unloading and Deformation Mechanism circular tunnel excavation unloading Tunnel. Specific results are as follows:① By solving the model after unloading the stress surrounding rock, and then Griffith strength criterion based on the calculated damage caused by a range of tunnel surrounding rock unloading, and in order to prove the correctness of the model;② Surrounding rock unloading time tunnel excavation blasting blasting time when determined by the model to calculate the maximum amount of displacement of the tunnel wall to 11.448 mm, which is the actual project monitoring data(usually no more than 10mm) are similar;③ For instance the static and dynamic unloading unloading comparative analysis, more consistent by calculating the dynamic unloading model with the actual project;④ By studying the mechanical effects of unloading circular tunnel surrounding the following conclusions: 1) tunnel surrounding different particle radial stress at a depth of surrounding rock unloading response to varying degrees; 2) unloading rate of speed on path greater stress impact, and to stress the impact of the cut is relatively small; the sooner the time when unloading rates, initial unloading stress damage range rock trend of expansion; while unloading rates slow, initial unloading little damage to the stress range effect on rock;⑤ Through the mechanism of deformation of the circular tunnel surrounding rock, obtained due to the nature of surrounding rock tunnel surrounding rock unloading caused by changes in the Complex(the Complex as a new rock), and is calculated by inversion comprehensive area, integrated deformation modulus of rock mass, integrated Poisson’s ratio and its variation;⑥ The rock mass is simulated by using finite element software unloading, computing the inverse performance of the rock mass in the area of integrated deformation modulus and Poisson’s ratio, and with theoretical results were compared and analyzed. Correction unloading caused by variation of mechanical parameters of surrounding rocks;...