Study On The Calculation Method Of Virtual Bypass In Well And Its Application In Foundation Pits Dewatering

Well has been widely used in foundation pits dewatering. With the difference in geological conditions, cost, construction and other factors ,it is to be divided into pressure dewatering wells, diving well, full well, and non-complete well and so on. In addition, in practical engineering applications, the well also produces well loss.About the FEM calculation method on well points, the conventional method is to refine mesh around the well. So it produces a huge number of units, less calculated efficient .And for large-scale models and a large number of wells it can not be calculated. This paper applies virtual bypass method, in almost no increase units case without loss of its accuracy. This method is not iterative and direct solution, and the computational efficiency is very high. In this paper, The calculation method in well consider these factors, and propose a simple realization method in general FEM procedure.Virtual bypass method is (outside the computational model) to add a bypass in the well points. It can use plane elements or body elements to simulate the bypass. The new bypass node water head is the actual well water head, and the well point head in original model is the calculated water head. By adjusting the parameters of bypass unit to simulate the flow near wells caused additional seepage path in order to achieve the purpose of the amendment.In foundation pits dewatering, the arrangement rule spaced wells can be calculated with multiple wells; when the wells arranged in an irregular group of wells, it must be calculated with three-dimensional model. In the long list of the well, it is modified in the filter nodes of multiple wells and in the bottom nodes. In three-dimensional well points, it is modified in the filter nodes and considered the loss of the well, eventually reached a high accuracy.Virtual bypass method is applied to the foundation pits dewatering and calculate some examples, including a complete calculation of wells and non-complete wells in section plane model, the pit floor whether or not be digged through the clay layer, infiltration around phenomenon and the different well spacing model in three-dimensional model. Through a large number of examples show that virtual bypass method can solve various problems in the foundation pits dewatering, and can achieve very high precision.Through analyzing the foundation pits dewatering of a engineering case, it can use virtual bypass to calculate. It is coincided with measured results and research report. The results are reasonable, and consistent with project rules.