Analyzed The Stability Of Surrounding Rock And Simulated The Construction By FEA For Double Multi-arch Tunnel

The double multi-arch tunnel which is a new large span tunnel is presented with the rapid development of high way building in our country. Its route is fluent and impropriating the area is small and the ratio of utilizing space is high. It is easy to connect the out road with avoiding the embankment in the tunnel exit or the bridge framing. It has the advantages of adapting the condition and protecting the environment and engineering quantitatively. The removing building is reduced and the engineering charge is reduced by using the double multi-arch tunnel during the construction in city. The double multi-arch tunnel is designed under the condition buried shallow tunnel with the moderate to short length. The surrounding rocks will happen when the load is removed and returned and the stress will be redistributed during tunnel digging. The surrounding rock will lose the stability when its strength is too low to adapt the stress redistribution. It will bring out the deformation and failure of surrounding rock if we do not reinforce timely or cannot assure the quality of reinforcement, which will take some disadvantages for the construction and operation of the underground building. Because the geological condition is poor during the construction of double multi-arch tunnel, the hidden trouble of the surrounding rock instability and desformation exists. So it is a important content with closely relating to the construction of tunnel and operation in the high way that analyzing the stability of surrounding rock. Base on the construction double multi-arch tunnel of the Nanshi-Mengyang high way, the tunnel construction is simulated by analyzing the stability of the surrounding rock and protecting the stability of the surrounding rock and supervising the construction. The most weakness site of the surrounding rock stress strength is pointed out during the process of the tunnel construction. The local instability and breakage of surrounding rock is forecasted and prevented which can assure that the stability of surrounding rock can arrive at the requests. The stability of surrounding rock is analyzed systemically by the methods of combining the body analysis with the local analysis. At first, base on the geological engineering factors of influencing the stability of surrounding rock, the mechanism of deformation and failure for the surrounding rock is analyzed and discussed. Aim at the geological characteristics of the elastic-plastic properties of the structure face and the shallow interlayer, the strength-stress controlling mechanism is thought as the main mechanism of deformation and failure. The destroy manner of spreading collapse and fracture flaking is the main manner for the surrounding rock.. Secondly base on the engineering geological condition of the double multi-arch tunnel in the Nandao river, the factors of the initial geo-stress and the underground water and the weak structure surface is modified properly by utilizing the national code "Classification Standard for Engineering rock". The classification of surrounding rock of double multi-arch tunnel in Nandao river is analyzed exploringly. The quality index (BQxLD) of surrounding rock is confirmed which can use to reference for the classification of surrounding rock. The classification of the surrounding rock is the â…¡ type by analyzed all kinds of classifications of surrounding rock. The tunnel construction is simulated by the program of ANSYS after building the elastic-plastic model. The stress states during the construction is simulated. The rules of the stress and distortion in the surrounding rock and structure is analyzed detailedly for the double multi-arch tunnel building in the three hole. The elastic space model is built at last. The space effect during the dig of double multi-arch tunnel and the interactional of the right hole and left hole is simulated, at the same time the distortion of dividing-wall is simulated too. It can give some advances for the design and the construction of double multi-arch tunnel in the soft rock.