Study Of A Deep Foundation Pit Of Chengdu City

In recent years, with the high speed development of city building, the underground space is farther developed and utilized. Consequent some new underground structure types appear, such as subway station, underground mall, underground parking, underground civil defense fortifications and kinds of civil and industrial facilities. The complicate engineering geological condition and the deeper excavation bringing relevant problem to the develop of the foundation ditch.For the complicate engineering geological condition, there are shoring structures with many kinds of foundation ditch shoring types coexist.For the deep foundation pit, the thesis makes use of finite element software as a tool and combines with the deep foundation pit design plan which is row of piles together with pre-stressed cable to build simplified the three-dimensional finite element model.In the simplified model, the soil mass uses ideal elastoplastic model, and row of piles pile uses beam unit, and reduces the row pile top champions beam and the pile spray nets structure. The pre-stressed cable use link units, pre-stressing to the cable through decrease the temperature. The ANSYS software takes advantage of Birth&Death function of itself to simulate dynamic excavating and shoring process. Compared the site data monitoring with simulation result and made a proper conclusion, all of these results supply theoretical direction to the same project.In order to get the foundation pit shoring structure deformation and the subsidence of the surrounding soil of the foundation pit characteristic, the thesis mainly studies of numerical simulation of dynamic construct process of deep foundation pit. The study method is making use of finite theory to simulate the shoring plans of foundation pit, then analysis the simulation result.In the end, the conclusion is that the biggest deformation value of the pile appears in the top of the piles, and the biggest subsidence occurs far from9meter of the foundation pit. Simulate the influence exerted by excavating the pit which is33.5meter distant from the subway line, come to the conclusion that excavating the pit has no effect on the subway line. For the buildings around the pit generally away30meters from the supporting pile of the pit and the foundation of the buildings are managed with the corresponding reinforcements, so excavating the pit has no influence on the buildings around the pit too. The anchorage points location of the pre-stress cable is of great meaning, Pouring concrete crown beam on the top of support piles can effectively control the deformation of the shoring structure. In order to ensure the safety and order of the constructing process, excavating the soil internally, and the excavating and the shoring measures should be done at the same time.