The Research And Application Of Construction Technology Of Shallow-buried Tunnel Under The Buildings In Aobaogou

Since our country is a mountainous land, during the rapid development of railway construction, the construction of a great number of tunnels is necessary to overcome the obstacles of plane or elevation, so as to improve the standard for the line and reduce the operation cost. Aobaogou Tunnel is the key project for Batuta-Diandaigou Railway. The tunnel passes through the staff quarter, staff dinning hall of Xiliang Coal Mine and Xiliang Coal Mine Transformation Substation. The minimum depth of the earthing on top of the cave is approximately 20 m. The burial depth of the tunnel is shallow, with a large span. The underneath excavation of the tunnel has a large influence over the surface buildings, posing great construction risk. Therefore, it is necessary to take reasonable construction methods to ensure the safety of buildings during the underneath construction of Aobaogou Tunnel.The thesis makes research of the construction problems during the underneath construction of the shallow-buried Aobaogou Tunnel from the aspects of structural features of buildings, the surface deformation forecast due to the tunnel excavation, the tunnel construction monitoring measurement and the deformation law caused by the tunnel construction and the blast vibration test law of the construction of the building where the tunnel passes through underneath. The main conclusions are as below:(1)As the tunnel passes through the building underneath, the surrounding rock is mainly soft soil of relatively poorer self-stabilization capacity. Excessive settlement is likely to occur due to excessive deformation.(2)Seen from the analysis of the spatial relationship between the surface building and the contour line of tunnel excavation, with the closer distance from the tunnel vault to the building foundation bottom, the excavation of the tunnel has a relatively larger influence over the building.(3)By means of Peck Formula and analytic methods, the forecast is made of the sedimentation value for the construction surface of building where Aobaogou Tunnel passes through underneath. The forecast result is that the surface deformation value could reach 54 mm as the tunnel passes through the building underneath.(4)The analysis is made of the displacement and the variation law of stresses during the tunnel excavation by use of the numerical simulation software FLAC3 D, and the improvements are made of the construction technology according to the variation law.(5)The analysis is made of the law of the changes by vault crown settlement and horizontal converge as the time and construction procedures proceed. It is concluded that the tunnel undergoes rapid deformation within two weeks after the excavation and generally gets restrained within one month.(6)The analysis is made of the changes by differential settlement of the building foundation, the surface settlement and building foundation settlement as the time proceeds. It is concluded that the sphere of influence of lateral settlement of the excavated tunnel is 20 m.(7)The law of blast vibration is clarified from the aspects of power spectrum, vibration waveform time domain and vibration velocity, and the formula for forecasting the blast vibration of the building where Aobaogou Tunnel passes through underneath is obtained. The measures for reducing the blast vibration and the technology for the construction of the buildings where the shallow-buried tunnel passes through underneath are provided.