Analysis Of Bearing Capacity Behavior Of Existing Building Foundation Pile By Pumping Water

Since the new century,as the economic development and urbanization have accelerated,human demand and exploitation of groundwater are increasing.The problem of ground subsidence caused by over-exploitation of groundwater has become more and more serious.The ground settlement is bound to have an important effect on the existing building foundation piles,and may also pose a threat to the safety of the structure.At present,there are few reports on the analytical solution of the nonlinear consolidation of soft soil caused by pumping water,and the analytical solution of the bearing capacity of pile considering the time effect based on the influence of pumping water.In this paper,the classical nonlinear relationships are introduced to describe the nonlinear compression and permeability characteristics of soil,the analytical solution of one-dimensional nonlinear consolidation of soft soil layer by pumping water is derived,and the consolidation behavior is analyzed;Based on the load transfer model,the analytical solution of the negative friction of pile foundation with the development of time and space is obtained,and the influence of various factors on the bearing capacity of pile foundation is analyzed.1.Based on the theory of one-dimensional linear and nonlinear consolidation,the governing equations of one-dimensional linear and nonlinear consolidation of soft soil layer are established when the water level of the phreatic layer drops over a large area over time,and the solution conditions are given.The general analytical solutions of one-dimensional linear and nonlinear of soft soil layer when the pumping water occurs in the phreatic layer are obtained by using the method of separation of variables,and the analytical solutions of the special precipitation such as the instantaneous drawdown of water level and the single-stage constant speed drawdown of water level are derived.Based on the analytical solution of the model,the influence of the dropping rate of groundwater table,tthe final dropping value of groundwater table and the natural gravity of sand layer on the consolidation behavior are analyzed.2.The governing equations for the consolidation of the soft soil layer when the water level of the confined aquifer drops over a large area over time are derived.According to the definite solution conditions,the one-dimensional linear and nonlinear general analytical solutions of soft soil layer when pumping water occurs in the confined aquifer layer,and the analytical solutions under special precipitation modes such as the instantaneous drawdown of water level and the single-stage constant speed drawdown of water level are derived.The influence of the dropping rate of groundwater table,and the the final dropping value of groundwater table on the consolidation properties.3.Based on the analytical solution of one-dimensional linear consolidation of soft soil caused by the instantaneous dropping of water level in the phreatic layer,using the pile-soil load transfer model,the analytical solution of the development of side friction of foundation pile with time and space is derived when the pumping water occurs in the phreatic layer,and the influence curve of pile radius,time factor,pile top load and water level drop depth on pile shaft force,pile end reaction force,neutral point position and pile side friction is drawn The influence of various factors on the bearing capacity of foundation pile is analyzed.4.Based on the analytical solution of one-dimensional linear consolidation of soft soil caused by the instantaneous drop of water level in the confined aquifer,through the load transfer model,the analytical solution of the development of pile side friction resistance with time and space is obtained when the pumping water occurs in the confined aquifer,and the influence of pile radius,time factor,pile top load and water level drop depth on the bearing capacity of pile is analyzed.