| In recent years, with the rapid increase of the foundation pit depth to20-30meters, a lot of deep and asymmetric foundation pit exists in our city. In soft soil areawhich is full of water, the project of excavation of foundation pit will face theproblem of under-ground water inevitably. If we use the water stop curtain orunderground continuous wall on the confined aquifer under the bottom of thefoundation pit truncation, we may find that the underground continuous wall is ahighly cost and difficult construction, and its reliable quality can not be guaranteed.Considering the above difficulties, the paper makes some points on followingaspects.(1) In the view of the asymmetric excavation, through the analysis of the wholeconstruction process of the measured data, the paper make the study of process law ofhorizontal displacement of the retaining structure of foundation and deformation ofthe wall. At the same time, in the view of the symmetric and asymmetric offoundation pit, carrying on the numerical simulation of the step-by-step excavation ofthe precipitation through the finite element method. Through the comparative analysisof deep foundation pit deformation and stress distribution caused by asymmetricnegative rule, and compared with the measured data of the construction processanalysis, summarizing the rules of structure deformation behavior which is caused inthe process of precipitation step-by-step excavation of foundation pit. Finally, makingsome reasonable suggestions for the asymmetry foundation pit design andconstruction.(2) Finite element numerical model is set up for decompression process influenceon pile foundation. The numerical simulation result shows that as the decompressiongoing, the pile friction resistance is significantly decreased and even negative frictionresistance exists. However the target aquifer and its adjacent to the upper part of thewater-resisting layer appeared inflection point "S" type, making the pile resistance instep-down target aquifer appear larger increase. The law is also embodied in the stressof the pile body, appeared in the pile body stress of water-resisting layer increases theinflection point, the non-uniform change of pile body stress will have an adverseimpact on its own strength and deformation.(3)For the deep underground confined aquifer distribution conditions, couplingnumerical model of the three-dimensional is established. By the pumping test, measurement and the comparison of numerical simulation analysis, taking the studyof the different control strategies of the confined water. As the main line of the depthof underground continuous wall, making the research of the different depth ofunderground continuous wall under the condition of confined water headcontrol,water output, deformation caused by environment, comparative environmentaldeformation control standards. Optimizing the depth of underground continuouswall. Exploring the low pressure to pile and pile body stress the influence of negativeskin friction resistance and different depth of underground continuous wall protectionof pile foundation.(4)Conducting the on-site injection experiment to get the recovery of confinedwater level between adjacent layer and aquifer. Summarizing the influence of singlewell injection and injection related to ground the springback deformation law. At thesame time, through the numerical method to simulate the injection test, fitting theobserved aquifer water level, getting the comprehensive three-dimensional numericalmodel for groundwater recharge test. Combined with the engineering practice of pitdecompression, making the whole process of trial and comparing with the numericalsimulation analysis. Carrying on the research in the presence of water stop curtainwhen the coupling effect of pumping and injection influence scope and recharge ofgroundwater seepage properties and injection well arrangement, recharge amount andits relationship with the ground bounce, recharge for both the protection of thebuilding. |
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