Mechanical Properties And Consolidation Effect Analysis Of A New Deep Foundation Pit Supporting Structure

Drainage plate combined with grillage self-drilling tire tandem anchor is a new supporting structure for deep foundation pit, It is used to solve the problem of foundation pit dewatering and support in soft soil area, this new supporting structure combines the consolidation measures and the bit expanded anchoring technology together. And comprehensive treatment of deep foundation pit engineering in soft soil area by utilize the good precipitation effect of drainage plate, and the characteristics of squeezing and compaction of soil under the action of expansive pressure, and the performance of cooperative work in space of grillage and anchor. The mechanical properties and consolidation effect of drainage plate combined with grillage self-drilling tire tandem anchor in this paper is analyzed by the method of theoretical analysis and numerical simulation, the specific research contents and conclusions are as follows:(1) Introduce the structure composition, construction technology and structure characteristics of drainage plate combined with grillage self-drilling tire tandem anchor. And the working mechanism are discussed in detail, the results show that:the consolidation process of the drainage plate can be divided into normal consolidation stage, pre-stress consolidation stage and compression consolidation stage; the working mechanism of self-drilling tire tandem anchor can divided into elastic stage, plastic zone development stage, plastic zone expansion to the through stage.(2) It can be known that the soil could produces a small cylindrical shear failure and large cylindrical shear failure under the action of anchor tensile through analysis the soil failure mode between the tires, Based on the theory of column hole expansion, The calculation formula of tire expansion pressure in the consolidated soil and saturated soil is given, And the soil pore pressurematrix calculation formula caused by tire expansion is deduced also,Then, the calculation formula of ultimate uplift bearing capacity in the two failure modes is deduced; Finally, analyzes the tire critical spacing, and the tire critical spacing calculation formula is derived by utilizing bearing capacity calculation formula.(3) By using the nonlinear finite element software ADINA, the model of foundation pit excavation and supporting is established, The axial force distribution characteristics of self-drilling tire tandem anchor is obtained, The advantages of the new structure are verified by compared with ordinary anchor support, At the same time, The surrounding soil stress field and displacement field distribution law caused by tire expansion is obtained through the establishment of double tire anchor that in the consolidated soil and saturated soil pullout model, And obtained the relationship between the anchor uplift bearing capacity and radial strain of tire. The correctness of bearing capacity calculation formula is verified by comparing the numerical simulation results with theoretical calculation results; Finally, summarizes the uplift bearing capacity influence factors of self-drilling tire tandem anchor.(4) By using the nonlinear finite element software ADINA, the effective consolidation characteristic of drainage plate is verified by the foundation pit drainage three-dimensional model, The distribution law of pore water pressure of surrounding soil caused by tire expansion is obtained by the finite element pullout model of drainage plate composite with double tire anchor, the influence law of self-drilling tire tandem anchor uplift bearing capacity caused by drainage plate consolidation effect is derived also by comparing with pullout model without drainage plate.