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[摘要]
拱坝所处的运行环境复杂,受力状态复杂,其真实的工作状态往往与其设计状态存在一定的差异,因此开展基于坝体温度和变形监测资料,反演坝体与基岩材料参数,仿真坝体的应力状态的研究。通过有限元方法,基于小湾拱坝实测温度,拟合上下游坝面的温度边界条件,并对拱坝运行期温度场进行了仿真;基于变形监测资料,反演坝体和基岩弹性模量;基于反演得到的坝体温度场与材料弹性模量,对小湾拱坝进行应力仿真分析。研究表明:小湾拱坝下游面温度分布总体呈现出两侧坝段高于中间坝段的规律;运行期坝体混凝土的弹性模量相对于试验值约提高30%;在冬季时,上游坝面水位以上部分出现局部拉应力,下游坝面在坝基交界面附近由于应力集中出现局部拉应力,但不至于影响工程安全运行。
[Key word]
[Abstract]
The arch dam is a three-dimensional shell structure with a complex operating environment and complicated stress state,its actual working behavior is different from the design condition.During the operation of a high arch dam,the temperature load,which is determined by the difference between the temperature field during operation and its joint closure temperature field,is one of the main loads.Generally speaking,it is easy to obtain the temperature field of arch sealing.However,thermal analysis of the arch dam during operation is difficult due to the influence of climate conditions,structural form,and operation modes.In addition,as the main waterholding structure,the stress state of the arch dam during operation is sophisticated.The mechanical parameters of concrete may differ from the experimental values.Therefore,the research on the real working behavior of the Xiaowan arch dam is of great significance. The material parameters of the Xiaowan arch dam were investigated and the stress distribution was simulated by the finite element method.The temperature distribution on the dam surfaces was fitted by the polynomial as the thermal boundary condition based on the measured temperature.Then transient temperature field of the Xiaowan arch dam was calculated step by step.The elastic modulus of dam concrete and foundation rocks were continuously adjusted to minimize the differentials between the numerical displacements calculated by FEM and the actual displacement measured by the plumb lines.The elastic modulus with the smallest displacement errors was viewed as the actual material parameters.The simulation of stress distribution of the Xiaowan arch dam was carried out based on the inversion results of the temperature field and material parameters. Conclusions (1)The feedback temperature field could represent the temperature field distribution of the Xiaowan arch dam during the operation period.The temperature of the upstream dam surface was mainly affected by the reservoir water.Besides,the temperature of the upstream dam surface near the foundation was higher,between 17 ℃ and 19 ℃ due to the influence of the ground temperature and slag in front of the dam.The temperature of the downstream dam surface was mainly affected by atmospheric temperature,showing a phenomenon that the temperature was higher on both sides than in the middle section.(2) The elastic modulus of the dam concrete during the operation was increased by about 30% relative to the test value.Besides,the deformation modulus of the bedrock was 20%~45% higher than the test value.(3) The calculated displacement agreed well with the measured data with the same trend.The displacement of the Xiaowan arch dam was closely related to the upstream water level.The dam had a trend of slow deformation to the downstream because the aging effect had not yet fully converged at present.(4) The upstream dam surface was basically in a pressure state.Besides,the maximum compressive stress,which was located at the height of 975 m,was about 10 MPa.However,the dam surface above the water level was under tension in winter,and the maximum tensile stress was about 0.6 MPa.The downstream dam surface was basically in a compressive state,and the maximum compressive stress could reach to 17.3 MPa,which was located at the dam toe.Besides,the te2nsile stress zone appeared near the interface between the dam body and the foundation due to the stress concentration,and the global maximum tensile stress was about 0.8 MPa,although the operating state of the dam was still in the safe scope. Conclusions(1)The temperature of the downstream dam surface was mainly affected by atmospheric temperature,showing a phenomenon that the temperature was higher on both sides than the middle section.(2) The elastic modulus of the dam concrete during the operation was increased by about 30% relative to the test value.(3)The stress distributions of the Xiaowan arch dam revealed that its operating state was still in the safe scope.
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