Calculation Method For Internal Forces Of An Inspection Well In Heating Project

Theoretical method and numerical method are often used in calculation of internal forces of inspection wells. According to boundary conditions, a slab can be simply supported, fixed and elastically fixed. FEM numerical method can be used to calculate internal forces for an inspection as a whole.In design of heating projects, theoretical method is mainly adopted in calculation of internal forces of inspection wells, in which an inspection well is divided into six slabs and calculated separately. Then the slabs are reinforced according to the moment. In doing so, the coordinated deformation of six slabs is ignored, and it is difficult to consider the influence of an opening or a hole to internal forces. As a result, the design is usually too conservative, causing material waste. On the other hand, numerical simulation usually gives results which are too small. If adopted, the design can not guarantee enough safety margin. To solve this problem, this paper focuses on a new method which can be used in design of heating projects.The main contents and conclusions are as below:(1) Taking a well as six slabs with four-sides simply supported and fixed respectively, internal forces are calculated thereotically.(2) Shell63element is used and the internal forces of wells are computed by ANSYS software.(3) A frame method is proposed and inspection wells are calculated by this method. Comparison is conducted over the results by theoretical method, numerical simulation and frame method. Upon the comparison, the loads on the frame are modified, which leads to more rational results. Then two wells with length-to-width ration being2:1are calculated, which shows that the frame method can also give correct results.(4) The frame method is used to an engineering case and verified.According to the comparison on results by theoretical method, numerical simulation and frame method, the results by frame method lie between theoretical method and numerical simulation. For the moment at center of a simply supported slab, theoretical method gives the largest value while numerical simulation gives the smallest. For the moment at four sides of a fixed slab, theoretical method gives the largest value while numerical simulation gives the smallest.The results of this paper provide a good reference for design and further research of inspection wells and other underground structures.