Study Of Foundation Pit Deformation Law Of Retaining And Protection With Reinforced Cement Soil Piles And Anchors

Reinforced cement-soil pile anchor supporting structure is a new technology of deep foundation pit supporting.This technology has been successfully applied in some foundation pit supporting engineering in soft soil area. Especially it has been applied successfully in the thicker silt soil area. But at the moment it is rare that the engineers support of the theoretical research on the deformation law of reinforced cement-soil pile anchor foundation pit.Most of the research stay in the field monitoring and numerical simulation. Theoretical research lags far behind practice. Therefore, in order to be better application in practical engineering and promote it,it is particularly important to use the theoretical method to study the foundation pit deformation law. This article will be combined with the actual project from theoretical analysis, numerical simulation, field monitoring to study the foundation pit deformation of reinforced cement-soil pile anchor. The main contents are as following:(1) By reading lots of literature,the physical and mechanical properties of soil are summarized in the soft soil area. These physical and mechanical properties include: water content, heavy, compressive strength, tensile strength, shear strength, deformation modulus, compression coefficient, compression modulus and poisson’s ratio.(2) From the form and mechanism of action of the reinforced cement-soil pile anchor supporting structure, the theory of composite foundation reinforcement and the reinforcement theory are introduced when the reinforce principle of active earth zone of the cement-soil pile anchor support foundation pit is explained. The method of energy safety factor is used to analyze stability of this supporting form foundation pit. The safety coefficient calculation formula is deduced.(3) Combining the theory of composite foundation reinforcement, the principle of minimum potential energy is been used to deduce the deep horizontal displacement of the retaining wall. Then combined with the existing relations between the soil deformation after pit and the retaining wall deformation, the predictive analytics of the deep soil horizontal displacement and the surface subsidence are proceeded.(4) FLAC/3D finite element software is been used to analysis of the influence which the reinforced cement-soil pile anchor support of foundation pit deform under the various factors, (the width of retaining wall,the depth of the retaining wall, the length of inclined anchorage pile,the diameter of inclined anchorage pile,the interval of inclined anchorage pile, internal friction Angle of cement-soil, cement-soil elastic modulus, etc.)(5) As an example,zhuhai international building foundation pit engineering is analyzed. The deep soil horizontal displacement and the surface subsidence of the test section of foundation pit are monitored. And then,combined with the monitoring data,the deformation law of foundation pit is analyzed.(6) Using finite element software FLAC/3D to establish zhuhai actual engineering numerical model,then the numerical simulation of foundation pit deformation and stability has been done. The calculation results were analyzed and the foundation pit deformation law is summarized. The model is divided into two kinds of situation:1) The model is constructed according to the actual supporting form; 2) The soil parameter of active area is adjustmented according to the theory of composite foundation and then the related model is established.(7) Combined with the theory analysis conclusion about the stability of foundation pit and soil deformation in this article,the theoretical calculation and analysis is done of foundation pit in zhuhai. And the field monitoring results, the theoretical calculation results and numerical simulation results were compared.