| With the accelerated process of urbanization in china, high-level and super-high-rise building is continue to increase, the corresponding excavation depths are deeper and deeper, but at the same time, China’s urban land is decreasing, the pit surrounding environment has become increasingly complex, a single soil nailing support form can not meet the requirements of the foundation pit deformation. Therefore, designers have developed a structural form on the basis of soil nail wall, the supporting structure composed by different single support. Such supporting structure has now become the main development direction of China’s foundation pit.The Micro-piles, Anchor and soil nailing compound supporting structure combined to make up for the lots of defect of the ordinary anchor and soil nailing compound supporting structure along with the restrictions on use, so it gradually being applied to deep foundation pit engineering. First, this thesis is base on a foundation pit engineering project in Zhengzhou zone, monitoring the axial force of soil nail and anchor by distributed optical fiber sensor, according to measured date, the role of the change of axial force is discussed. The computation models for micro-pile, pre-stressed anchor plus soil nail supporting system are established using FLAC3D, and a construction process simulation of foundation excavating and support is conducted. Through comparative analysis of two models, the role of the micro-pile in the compound support structure can be drawn. Finally, Micro-piles, Anchor and soil nailing compound supporting structure are analyzed through variable parameter simulation. In this paper the main achievements gained include:(1) Summary of the soil nail and anchor in the supporting structure and their interaction through the analysis of measured data.(2) To use numerical simulation methods, comparative and analysis the force and the pit deformation law of two kinds of supporting structure, then we can make a conclusion that mini piles supporting structure has strong ability for constraint deformation, and it also can improve the soil nail and the stress of anchor.(3) Anchor effective constraint the displacement of the soil near the anchor layer, then it play the role of sharing stress on soil nailing, we know it through the simulation analysis that soil nailing may be has the phenomenon of axial force decrease in the early tension of anchor, however with the excavation of the foundation pit, soil mass stress will diffuse and distribute afresh, finally soil nail will mainly affected by the pull force.(4) Miniature pile spacing and the variation of pile diameter significant impact on the soil nail in the supporting structure and the anchor’s stress; The variation of soil nail length has obvious influence on soil nail itself and anchor’s stress, but failed to mini piles bending moment. The variation of anchor length almost no influence on the stress of supporting structure. |
