Finite Element Numerical Simulation And Optimal Design Of Supporting Piles In Deep Foundation Pit

With the continuous expansion of the scale of the city and the increase of population, in order to ease the traffic situation in Shenyang City, convenient public travel, Shenyang began to build the subway, followed by a large number of deep foundation pit excavation. The supporting structure is widely used in deep foundation pit support engineering because of its strong adaptability to surrounding environment, convenient construction and good safety and stability. But in actual engineering, the design of supporting engineering is relatively conservative, can not play a role in the cost savings. If we can optimize the detail parameters of supporting structure, it can satisfy the requirements of stability, and can reduce the cost of building envelope, which can bring great economic benefits. Therefore, it is necessary to carry out the numerical simulation study on the supporting structure of deep foundation pit,and accumulate some experience in this field.Taking Shenyang subway deep foundation pit support design as an example, using ABAQUS finite element software of standard of deep foundation pit row pile with supporting structure numerical simulation analysis and with the measured data compared to verify the correctness of the finite element model. At the same time, the length, diameter and spacing of the supporting piles are optimized, and the best scheme is obtained.The main results of this paper are as follows:(1) Overall, the horizontal displacement of the supporting piles increases with the increase of excavation depth, and the maximum displacement is moved up to the top of the pile in the setting of second support; From the local observation, the pile body horizontal displacement along the pile embedded depth increases first and then decreases, the curve is bow, that the prestressed steel support for the restraint of the horizontal displacement of the pile has played a very important role.( 2) After the completion of the excavation of the soil, the support of the vertical displacement of the pile is not affected, which is due to the pile body and the surrounding soil in support of the stress has been fully released, the strain is basically completed.(3)The soil around the foundation pit supporting piles have different degrees of uplift,and with the increase of the depth of excavation. This is mainly due to the excavation process,the stress is released, and the foundation pit is driven by the uplift of the retaining piles,which cause the soil around the pile up.( 4) After the excavation of the soil pressure, the maximum variation of the soil pressure in the second layer is the biggest, and the numerical simulation of the soil pressure is obviously reduced after the first excavation, which indicates that the excavation and support of the second soil layer is the key to the project.(5)Through the orthogonal experiment, the optimal calculation of the supporting piles can be obtained. The influence of the horizontal displacement of the supporting structure is the pile diameter, the second is the length of the pile, and the pile spacing.