The Application And Research Of Cement-soil Pile And Soil Nailing Supporting Technology

In recent years,with the development of economy,the real estate has also got a rapidly develop,high-rise buildings have sprung up,the floor space is becoming increasingly scare,so utilization of underground space is becoming a kind of trend.A problem must faced when concerned about utilization of underground space---the foundation pit supporting.Soil nailing supporting was accepted,because it has the advantages of simplicity,rapidity,economy etc,and at the same time it also has some disadvantages,for example,it can't be used in the soft soil area,and is also not suitable for the complicated surroundings.It greatly limits the application of this supporting technology.Under this background,the composite soil nailing supporting developed,it takes the advantages of other supporting technologies to make up the shortage of pure soil nailing,and also remains lots of advantages of soil nailing supporting.However,the composite soil nailing supporting started late, its mechanism of action is not clear, the theoretical basis is not sufficient, it relies more on the experience.For more in-depth understanding of composite soil nailing system, and make the technology more widely used,this paper takes cement mixing pile composite soil nailing supporting as an example,uses the finite element software---abaqus to simulate and analyze it to explore the mechanism of composite soil nailing,summarize the rules of deformation and internal force of composite soil nailing supporting.The paper also makes an optimal design for parameters of soil nailing,and gives a reasonable suggestions to the best thickness of mixing pile and the best depth between mixing pile and bottom of pit.Main work and innovation of this paper as follows:(1)Stated the advantages and disadvantages of soil nailing supporting firstly,and then stating the composite soil nailing supporting.Because the theoretical research of composite soil nailing supporting is outdated and the mechanism is also unclear,the paper will take mixing pile composite soil nailing supporting as an example to make a further research for composite soil nailing supporting.(2)Took a few specific application of mixing pile composite soil nailing supporting technology as an example,pointing out under which conditions did the mixing pile composite soil nailing supporting apply with an obvious advantage.(3)Discussed many aspects about the stability checking of mixing pile composite soil nailing supporting,and then going on with a formula derivation.(4)Supposed an ideal model and going on with a numerical simulation on the basis of the finite element software--abaqus,and getting the change rules of horizontal displacement,surface subsidence,bottom heave for mixing pile,and also the change rule of soil nailing and internal force of mixing pile.At the same time,it also makes an optimization design for parameters of soil nailing.And finally,discussing the best thickness of the mixing pile and the best depth to the bottom of pit.(5)Combined with a specific engineering project and using the finite element software to simulate it.Then compared its results with the actual monitoring data and the calculating results of Lizheng software and finally get a result that deformation rule is reasonable to some extent.And also gives some comments on the parameters selecting of supporting structure in the examples and provides some reference information for design.