【作者】 宋常；

【导师】 周晶； 冯新；

【作者基本信息】 大连理工大学 ， 水工结构， 2011， 硕士

【摘要】 中国是世界上水力资源最丰富的国家之一,而西部地区是我们国家水能资源最丰富的地区,所以我国将在西南地区建设一批世界级的高混凝土坝。鉴于西部地区处于强震区,本文对混凝土重力坝在地震作用下的损伤破坏进行了深入的研究。在宏观均质假定的基础上考虑混凝土材料的抗拉非线性,基于大型通用软件ANSYS的二次开发将弹性损伤力学的本构关系以更新单元刚度的方式植入损伤计算过程中,初步建立了易于操作和实现的大坝动态损伤分析方法,并应用于工程实例卡拉水电站重力坝的地震破坏研究中。具体的内容主要包括以下三个方面：(1)数值计算的结果是否准确需要经过实际工程的检验,但混凝土重力坝属于大型工程,且遭受强震的震害实例比较少,根据有限的数据验证数值方法的准确性还存在较大的困难。为此,本文首先基于ANSYS自身的计算平台对仿真混凝土重力坝的振动台试验进行了数值模拟,主要的计算内容包括静力分析、模态分析和时程分析。由于目前仿真混凝土材料的动态性能测定方法的发展还不纯熟,所以计算的主要目的是通过模态分析得到符合重力坝基频测量值的混凝土动态弹性模量,和通过时程分析得到符合重力坝各个高程加速度测值的材料的动态抗拉强度。(2) ANSYS软件对于非线性本构的模拟能力有限,为了将更加符合混凝土损伤开裂的应力应变关系准确地植入数值计算中,本文将所用的ANSYS软件进行了二次开发。通过对ANSYS求解过程的优化,使时程计算能够随着时间和坝体受力的推进逐步调整单元的弹性模量,以拟合带残余强度的双折线损伤演化模型。用所建立的损伤计算模型分析重力坝的动态响应,将计算得到的加速度结果与振动台试验得到的坝体各个测点加速度值进行对比,给出了相差比率。深入分析了重力坝模型在不同强度地震动作用下的损伤发展以及开裂状态,给出了破坏单元的损伤发展时程图,并将分析结果同阻抗仪的损伤测量结果和宏观裂缝进行了比对,验证损伤计算方法的可行性。(3)混凝土重力坝的动力损伤分析目的是对已建或拟建的大坝施以一定强度的地震动激励,来探求随着时间推进重力坝各个部位的受力状态和损伤发展。本文根据卡拉水电站重力坝的具体工程实际,利用上文给出的损伤计算方法分析了大坝的动力灾变情况,并将计算结果与线性分析进行了对比,给出了卡拉重力坝在设计和校核地震动作用下的损伤状态。更多还原

【Abstract】 China is one of the most rich countries in hydropower resources of the world. In consideration of the abundance of the hydropower, there will be constructed quite a few high concrete dams in the southwestern region. Because of the strong earthquake in the western region, in-depth research for the seismic damage of the concrete dams are conducted in this paper. The consideration of the tensile nonlinear of concrete materials is based on macro homogeneous assumption. According to the secondary development of ANSYS, the constitutive relationship of elastic damage mechanics is implanted in the calculation process by the way of updating the stiffness. As an easy operating’analysis method, the dynamic damage model is set up, and it is applied to study the seismic damage of Kala gravity dam. The contents of this paper include the following three aspects:(1) The accuracy of numerical results needs the actual project’s inspection. However, concrete gravity dam is a large project, and the damage examples suffered strong earthquake are less, that will have a significant difficulty to evaluate an analysis method according to the limited data. Therefore, based on ANSYS computing platform, the shaking table test of simulation concrete gravity dam is simulated, and the contents include static analysis, modal analysis and the time history analysis. Due to the immature determination method of the dynamic performance of simulation concrete, the main calculational purpose is to get the dynamic elastic modulus which tallies with dam’s foundation frequency through modal analysis, and the dynamic tensile strength which tallies with the measuring acceleration through time history analysis.(2) The ability of ANSYS is limited on nonlinear constitutive simulation, So it has been used for the secondary development in order to be more in line with the stress-strain relationship of concrete damage during the numerical calculation. Through the optimization of ANSYS solving process, time history calculation can adjust the elastic modulus of elements with time and the advancement of stress, that can fit with bilinear evolution model. Dynamic response of gravity model dam is analyzed with the damage calculation model established in this paper. The acceleration results are compared with measuring acceleration data in the shaking table test on each point, and then the difference ratios are given. On this basis, damage development and cracking condition of model dam are in-depth analysis under different seismic intensity, this research also provides the elements’damage development figures and compares with the measuring data from the impedance meter and the macroscopic crack, that verifies the feasibility of damage calculation method. (3) Seismic damage analysis of concrete gravity dam is to explore the stress and damage development as time promoting of existing or proposed dam with a certain intensity of .seismic waves. According to the damage calculation method mentioned above, dynamic damage situation of Kala gravity dam is analyzed in this paper. The calculated results are compared with linear analysis, and the damage status of Kala dam under design and check earthquake is given.更多还原