Research Of Deformation Laws Of Sand-pebble Layer Deep Foundation Pit In Chunxi Road Station Of Chengdu Subway

In the Recent years, lots of big cities of our country rose high tide of the city subway's construction.In the process of subway station construction, the research of foundation pit engineering's transformation regulation is an important problem, the control of transformation of foundation pit has direct influence to the stability of foundation pit, openning the exhibition of transformation regulation research for subway station foundation pit has the important engineering application value.This text takes Chunxi road station foundation pit engineering of Chengdu subway as background, adopting the method Including the theories research,the spot monitor and the numerical simulation combine together, to research the transformed regulation of the typical model of all the sand-pebble layer station foundation pit engineering of Chengdu, main contents and conclusions as follows:(1) Carried on an explaination for Chunxi road station deep foundation pit engineering of Chengdu subway, including the geology environment condition, the foundation pit engineering design, the foundation pit engineering construction and the foundation pit engineering monitor etc.(2) Carried on analysis to the monitor data of the Chunxi road station deep foundation pit, emphatically analysis the monitoring results of including the variety of Underground water level, the move of fender piles, the displacement of fender pile top, the decline of foundation pit edge, the stress of steel support and the stress of anchor cables etc, analysis shows:Fender piles of east side of foundation pit shows that the displacement of pile top is small, the displacement of pile bottom is big, deformation curves are diagonal line; and the monitoring curve move toward to the inside of foundation pit before install steel support, the monitoring curve move toward to the outside of foundation pit after install steel support; Fender piles of west side of foundation pit shows that the displacement of pile top is big, the displacement of pile bottom is small, deformation curves are diagonal line, and the deformation value are litter tan the fender piles of east side of foundation pit. Though the analysis, this results are relate to steel support load, the geology environment condition, the type of pile and the construction technology. Installing steel support make a big influence for the deformation of fender piles of foundation pit, after install steel support, deformation of fender piles are control, and the big pre axial force also make fender piles become deformation that ward to the outside of foundation pit.(3) Used FLAC3D to analyze the excavation and support of Chunxi road Foundation pit, carry on contrast the monitor result and numerical calculation result, research shows that:The deformation of Fender piles of east side of foundation pit are not completely consistent in those two methods, the monitor result shows fender piles move toward to the inside of foundation pit before install steel support, and move toward to the outside of foundation pit after install steel support; the numerical calculation result shows the deformation rate of fender piles move toward to the inside of foundation pit is control, and the deformation almost stopped after install the first row of steel support. Although there are differences between those two methods, but one thing the same, the deformation of fender piles move toward to the inside of foundation pit is control after install steel support, ensure the stability of foundation pit, only the degree of control is difference.The displacement of fender pile top, the stress of steel support and the stress of anchor cables are coincide in those two methods.Depending on the monitoring results and numerical calculation, this thesis analyzes the space effect of the transform of foundation pit, the result is that the space effect was very obvious in the foundation pit engineering.(4) Combine the research result of the spot monitor and the numerical calculation, this thesis analyzes the transformed regulation of sand-pebble layer foundation pit in Chengdu region, and through analyzes the transform influence factor in the Chunxi road foundation pit, put forward a measure control transform of the foundation pit.