非稳定温度场对坝体孔口应力的影响

摘要

混凝土重力坝正常运用情况下主要承受自重、水压力、泥沙压力、扬压力和温度荷载,温度荷载对坝体孔口应力的影响很大.与大坝接触的外界气温和水温为年周期变化的非稳定温度场边界,经过几十年的运行,可以认为坝体边界混凝土温度也为年周期变化的非稳定温度场.选取三门峡大坝3#溢流坝段为模型,采用三维有限单元法,按不考虑和考虑温度荷载两种情况,运用ANSYS软件将不同月份的温度场与静力场进行耦合计算,对3#溢流坝段的深孔与底孔进行了应力分析.分析表明,孔顶和孔底在较冷月份表现为拉应力,且超过混凝土的抗拉强度,故需在孔口周围配筋,在孔口运行过程中要保证钢筋不被裸露或侵蚀.%Under the normal conditions,the concrete gravity dam is mainly subjected to gravity, water pressure, sediment pressure, uplift pressure and temperature loads. After years of a dam prototype observation,it finds out that the temperature load accounts for a great influ-ence factor on the stress of the dam orifice.The surrounding air temperature and water temperature are the periodic changing unsteady temper-ature field borders. After decades of operation,it is considered that the concrete dam and bedrock temperature are also the periodic changing unsteady temperature field. It selected the No.3 spillway dam section of Sanmenxia Dam as a model, using three-dimensional finite element method and applying ANSYS to couple the different months temperature field and the static force field and analyze the stress of deep hole and bottom hole of the spillway dam by two cases of not considering and considering the temperature load. The analysis shows that the top of the hole and the bottom of the hole in the cold months show tensile stress and more than the tensile strength of concrete,it is necessary to con-figure the reinforcing bar around the hole,the hole in the course of operation to ensure that the reinforcing bar is not exposed or eroded.