Study On Deformation Law And Monitoring Of Foundation Pit Supported By Piles In Nanchang

Since the beginning of the new century,China’s urbanization has developed rapidly,and many high-rise buildings have been built all over the country.In recent years,nanchang area of high-rise buildings also show explosive growth,although the city developing rapidly,but at the same time also brought a lot of deep foundation pit in the development of security issues,with increasing city high-rise building,taller,deep foundation pit excavation area is to also big,excavation depth is becoming more and more deep,so it is necessary for the deep foundation pit excavation supporting structure stress deformation law and through analyzing the impact on the surrounding environment,thereby reducing the occurrence of safety accidents.At present,the supporting structure for supporting pile brace and reliable,relative economic cost in nanchang in deep foundation pit construction in high-rise building is very extensive,but we in nanchang area within the pile supporting system to support the understanding of the mechanical deformation law of less than,the excavation when the surrounding environment changes also did not fully understand,is only judging by monitoring data of foundation pit excavation and surrounding environment is safe,and the lack of in-depth analysis of the theory and mechanism.At present,more manual monitoring methods are used for monitoring,and the monitoring value has a large error.Therefore,the conclusion obtained through this method alone is not convincing enough.System is presented in this paper the summary of the pile in supporting force and deformation calculation method on the basis of a pile in nanchang in the capital of the supporting foundation pit support,for example,the reason is deep foundation pit supporting design 7.0 software has carried on the overall analysis on the stability of supporting structure,through the finite element software JK3 E influence to foundation pit excavation on the surrounding environment,simulated and analyzed,and the use of finite difference software FLAC3 D to foundation pit excavation process is simulated and analyzed the change law of supporting structure stress and displacement,and each group support steel quantity on the importance of the foundation pit supporting effects,Finally,the deformation law of the supporting system and the settlement law of the surrounding land surface during the excavation of the foundation pit are compared and analyzed by comparing the monitoring value and the numerical simulation value of the foundation pit.The main work and research results are as follows:(1)according to the design theory of steel structure,the strength and stability of the internal support structure of shaped steel subjected to adverse forces are checked,and it is found that the strength and stability of the support meet the requirements of the code.(2)analyze the stability of the support system during the excavation of the foundation pit,obtain the variation of the internal force and displacement of the support pile,and find that the influence of the foundation pit construction on the surrounding surface settlement is within the range of 12 m from the edge of the pit.(2)the stability of the supporting system of foundation pit excavation are analyzed,and the changes of the internal force and displacement of supporting pile,when excavation to the pit,foundation pit horizontal displacement change is "bow",namely the maximum displacement of the pile depth decreases after increasing first,at this time of the maximum horizontal displacement is 19.19 mm,is located in the foundation pit depth of 5.40 m;It was found that the influence of foundation pit construction on surrounding surface subsidence was within the range of 12 m from the pit edge,while the influence range of subsidence obtained by FLAC3 D software was within 30 m.The latter result was close to the monitoring value.(3)finite element software is used to simulate and analyze the influence of foundation pit excavation on the surrounding environment(underground pipeline),and it is compared with the actual monitoring data.It is found that the settlement value of underground pipeline is close to the alarm value and standard limit value,and the underground pipeline should be closely monitored during construction.(4)USES the finite difference software FLAC3 D to simulate the excavation,the whole process of analysis and uplifts,the pit retaining structure is obtained,the change rule of surface subsidence found uplifts of deformation law for "on both sides of small,middle big",the maximum surface subsidence in position for about 7 m from the edge of foundation pit,maximum ground surface settlement is 7.7 mm.The simulated value is compared with the monitored value.(5)by changing the number of internal supports of each group,A qualitative comparative analysis is made on the supporting effect of each group,and it is found that group B,C and E have A greater supporting effect than group A,F and E.