Study On Information Construction And Numerical Simulation For Multi-arch Tunnel Of Complicated Conditions In Highway

With development of economic constructing and highway in china,the type of multi-arch tunnel often is applied in special geologic and topography districts in order to get better technological and economical purpose. But it has some disadvantages including complicated geological conditions, big span, continual disturbing, complicated and unsteady structure. A phenomenon that it can be constructed hidden tunnel on one side of deep depth but can't on the other side of shallow usually appears in the opening of slope sector. In order to avoid great excavation and protect nature circumstance,the structure of special tunnel with half-tunnel &half-roadbed is an optimum pattern to be selected.Based on the Dianhuiping multi-arch tunnel engineering of Changji highway and it's need,in-situ monitoring was carrid out for multi-arch tunnel. Basing on the displacement of surrounding rock and indoor test,rock mechanics parameters including c,φare gained by back analysis. The thesis compares construction methods of middle heading bench and three heading bench on displacement field and stress field of surrounding rock , supporting and mid-partition using numerical simulation, three heading bench is commended under unsymmetrical pressure and complex geological condition. By founding analysis calculate model of half-tunnel &half-roadbed key section with FEM, reseaches the stress field and displacement field of the surrounding rock,of the stress field of the supporting structure and the ear wall when the unsymmetrical pressure ratio P is 7,4 or 2.5. Especially analysing the distribution of vertical stress in ear wall and overladen stretching stress on the out side and a advice that it should be prevented riping of the concrete is bringed forward. Considering the security and stabilization of half-tunnel&half-roadbed structure, it comes to a conclution that it is rational when the slope rate is l(P=4),also prove designer of practice engineering reasonable. Base on the datas of in-sute measurement,the displacement result of surrounding rock which is forcasted by using BP model of neural network is compared with test result, and proved accurated. Finally, the the results of numerical simulation that is more confirmed to direct enginreering design is contrasted result of in-site test.