Analysis On Surrounding Rock Stability Of Putao Mountain Extra-long Tunnel Ventilation Cabinet

Among extra-long highway tunnels, for the requirements of ventilation people must establish ventilation cabinet, which taken appearance of cavern group usually. Ventilation cabinet includes exhaust air tunnel, supply air tunnel, transport tunnel, pedestrian tunnel, equipment cavern, cross-passage etc. These caverns are often connected with main tunnel. Cross section span of them are wide and spacing of them are small. The key points of engineering are safety construction period and stability of surrounding rock. So it is must be judged accurately that stability of surrounding rock at the whole ventilation cabinet and intersection zone on branch tunnels excavation period.Relying on excavation process of Putao mountain extra-long tunnel ventilation cabinet, firstly calculased elastic modulus of surrounging rock at ventilation cabinet, secondly predicted and analysised the whole stability of surrounding rock at ventilation cabinet, finally used the calculased elastic modulus and simulated numerical modal of excavation process at ventilation cabinet, then analysised stability of surrounding rock at intersection zone on branch tunnels excavation. Contents and resulting achievement of this paper are as follow:①Adopted classification method of rock mass geomechanics, range of elastic modulus for surrounding rock at ventilation cabinet was obtained. Then adopted BMP90 program, a group of elastic modulus of surrounding rock were obtained. Finally combined these two method, coMParatively accurate elastic modulus was obtained.②Based on data of monitoring measurement, the whole stability of surrounding rock at ventilation cabinet was analysised. By using regression analysis method and model DGM(2,1)of grey system theory, predictive values of crown settlement and horizontal convergence for the section were obtained.③Based on D-P Yield Criterion, used ANSYS software and combined obtained elastic modulus and excavation process of ventilation cabinet, 3-D finite element numerical modal was established.④For the example of cross section which obtained by slitting the modal along axis of exhaust air tunnel, influence on stress and displacement of main tunnel and exhaust air tunnel was analysised at intersection zone on branch tunnels excavation period.⑤For the example of exhaust air tunnel cross section, influence on stress and displacement of surrounding rock for exhaust air tunnel was analysised on branch tunnels excavation period, obtained influence scope for parallel tunnels construction.