Effects Of Deep Foundation Pit Dewatering On Existing High- Speed Railway Bridge Pile Foundation

With the construction of high-speed railway, safety of high-speed railway line has become a key issue of public concern. Since the operating speed of high-speed railway is very large, which propose very high demands on security controls of high-speed railway. Wherein the impact on high-speed railway operations caused by deep foundation pit dewatering is very serious, it should arouse the attention of engineering. Combining the numerical simulation and engineering test, this article will study the variation law of seepage field, stress field, displacement field variation by deep foundation pit dewatering, identify the deformation mechanism of soil. Based on this study, it will focus on soil deformation to the influence of adjacent structures such as high-speed railway pile under different conditions, putting forward assessment methods for elevating the deformation caused by deep foundation pit dewatering. Finally it studies the control distortion effects on high-speed railway. The main contents and results are as follows:(1) Taking the deep foundation pit of Hu Qiu Wedding Center in Suzhou and Intercity Railway as construction examples, it analyses the pile-soil interaction. The results show that setting pile-soil contact element are more reasonable, more coinciding with actual engineering. Based on the results, it studies the influence of deep foundation pit dewatering on high-speed railway pile. Under the real condition, sealing curtain totally cutting the micro-confined aquifer, deep foundation pit dewatering has less impact on the surrounding environment. The water level in high-speed railway position reduced by 0.2 meters. The surface subsidence is 1.5mm. Vertical deformation of the largest pile is 1.3mm. The inclination angle of the track panel of 0.0002 degrees. Pit the closer distance, the greater the deformation of the pile in a pile,(2) It studies the influence of deep foundation pit dewatering on high-speed railway under different sealing curtain insertion depths, different distances between piles and deep foundation pit. It shows that the impact of high-speed railway foundation pit dewatering. The depth of insertion of sealing curtain percentage of 60% or less, with the insertion depth increases, the control effect of high-speed railway deformation is not obvious; more than 60%, the increase in the depth of insertion of sealing curtain can play a significant role in controlling sedimentation. As the different distances between piles and deep foundation pit, when the distance is near, the vertical deformation of piles changes greatly when increase the distance; when the spacing between them increase to a certain extent, the gap of vertical deformation decreasing.(3) It elaborates the assessment methods according to contrast and verification. This assessment method consists of two parts:comparison method between the pumping test, numerical calculations large well methods proves that the large well method can be used to determine the law as well large precipitation-induced changes in water level; The comparison between normalized computing method and numerical calculation method shows that, when drawdown is small, the results of the two calculation methods differ less. it can be normalized computing method for calculating pile deformation method. Studies have shown that this assessment method can be applied to engineering practice.(4) It analyses two control distortion effects on high-speed railway, including setting the isolation pile, grouting after pile. By setting isolated pile between Deep Foundation and High Speed Rail Bridge Pile, it can effectively control the high-speed railway bridge pile foundation deformation caused by precipitation. The closer the high-speed railway bridge pile, the more obvious protective effect. Given the isolation of the pile high-speed rail, it should be set up at a safe distance and high-speed rail between isolated pile; pile grouting technology can slow down the high-speed rail pile deformation in some degree. But its role was not significant. According to the results, the use of pile after grouting can only be reduced base settlement 10%, and this control measure may increase high-speed rail bridge pile deformation caused by dewatering. So it is not recommended to apply to the foundation pit drainage of high-speed rail resulting in deformation of the protection technology.