Study On The Support System Of Deep Excavation By Numerical Simulation

In recent years, as the urbanization process of the country continued to push forward, a large number of rural population swarm into cities, so that urban housing and transportation was increasingly tense. To alleviate this tension, the building trended to high rising, the depth of excavation was larger and larger, and had continued to trend in the development of deeper and more extensive, so that new difficulties and problems were emerged in the design and construction process of deep foundation. Therefore, it is necessary to do research on the deformation law of each member of support structure to better guide the design and construction of foundation. In this paper, a commercial building excavation support project in east China was taken for an example, the finite difference software FLAC3D was adopt to do numerical simulation on the supporting structure of south and north of foundation respectively. A detailed analysis of foundation deformation was made during the excavation, and the law of deformation was summarized as follows:(1) The maximum horizontal displacement of pile-anchor support (PARS) occurred on the top of the pile, and gradually decreased along the depth. The soil resilience of bottom was lager, especially in the vicinity of the pile shaft, the mutation of resilience was obvious. So the corresponding parts should be paid attention to avoid serious elevation of pile. The influence range of settlement was twice than the depth, the distribution of bolt axial force was uniform in the free section and decreasing in the anchorage section, a number of inflection points was produced on the moment of pile.(2) The distribution of horizontal displacement in the soil nailing section was different from tradition. Due to the applied pre-stress, the position of maximum horizontal displacement was continuous down with the excavation step and stop at 3/4 of wall after completion of the foundation excavation. The displacement of foundation top was small, and the resilience of bottom was farther small than pile anchor. Except for the soil nails'axial force first layer was decreasing straightly, the distribution of other layers'was like a date pit small in ends, lager in the middle.The results acquired by means of numerical simulation are basically consistent with the field data,which shows the method concerned in this thesis is reasonable and that the prediction before construction is proper is also proved.So theoretical basis and guidance are provided to actual engineering .Also, valuable design,construction and scientific research experiences are accumulated and provided to the similar engineering.In addition, the foundation soil was obvious regional, this simulation results only gave guidance to same supporting structure with similar geological conditions.