| In the paper , based on two-dimensional unsteady full penetrating well flowtheory , a finite element computing program is presented by applying Galerkin finiteelement method and numeric simulation of dewatering in unconfined aquifer duringits unsteady process is made . In addition , considered the interaction betweenseepage field and stress field in the course of dewatering and based on the essentialprinciple of geomechanics groundwater movement equation , coupling modelbetween seepage field and stress field is put forward , and numeric simulation ofcoupling model is made . Based on the theory and method of optimation , by establishing the objectfunction with the total dewatering expense of excavation and using response functionwhich induced by the finite element computing program and which reflectsrelationship between pumpage and water level lowering , groundwater flowmodeling and optimization techniques are used jointly to determine the optimaldewatering system design . Since the aquifer is unconfined , an iterative correctionprocedure is applied to account for the nonlinearity of the system. The optimization model is amixed-integer programming model anddesigned tominimize the completion cost of pumping wells and the total amount of pumpage .Result shows that the mixed-inter programming model depicts the most favorablesolution with respect to the number of wells required , the total volume of waterpumped and the depth of wells in the thick aquifer . It has been shown that the optimization model can simulate dewateing fieldwith complex boundary conditions and so the method is of practical significance , andthe optimization model with the total dewatering expense of excavation designated asobjective function is more favorable than the optimization model with the totalpumpage amount in practice . IIThe work presented herein provides valuable instructions for the desigin ,construction and management of the dewatering excavation . |
