堆石料弹塑性循环本构模型研究及应用

发布时间：2018-08-31 08:12

【摘要】：过大的永久变形往往是导致堆石坝震害的主要原因。准确预测堆石体的地震变形在堆石坝的抗震设计中尤为重要。目前广泛使用的等价粘弹塑性模型对堆石体在地震荷载作用下变形的描述具有很大经验性,只能粗略估算地震荷载引起的残余变形,采用循环弹塑性模型可弥补这一缺陷。本文在前人研究的基础上,着重对堆石料在循环荷载作用下的应力应变规律进行了总结,建立了一个实用化的三维弹塑性循环本构模型,提出了基于该模型的数值化方法,开发了基于开源动力有限元软件OpenSees的面板堆石坝动力计算程序。本文取得的研究成果主要包括以下几个方面:第一,建立了一个可合理地反映堆石料在循环荷载作用下应力-应变特性的三维弹塑性本构模型。与目前已有的弹塑性循环本构模型相比,该模型具有以下几个明显优势:1)提出了一个基于修正空间滑动面强度理论的双参数三维非线性强度准则,使复杂循环加载下堆石料强度的描述更为简便合理;2)可反映偏应力循环、球应力循环及二者共同作用下不可逆体应变的累积规律,使循环荷载作用下堆石料体应变的描述更为准确合理;3)可反映循环剪切荷载作用下剪应力-剪应变关系的滞回特性、硬化特性和应变累积特性,使循环荷载作用下堆石料剪应变的描述更为精细合理;4)共有11个物理意义明确的模型参数,均可由振动三轴试验测得的最大剪切模量、模量衰减曲线和残余变形累积曲线等常规试验结果来确定,使该模型更加实用化。第二,提出了该本构模型的数值实现方法,开发了基于开源动力有限元软件OpenSees的用户材料子程序以及针对面板堆石坝动力计算的辅助性前后处理程序,实现了较为高效的数值建模。通过对二维理想坝模型、三维均质坝模型的系列计算和对比分析,完成了对程序有效性的测试。第三,通过三维动力弹塑性有限元分析,较为合理地再现和揭示了紫坪铺高面板堆石坝的震动响应和变形规律,模拟结果与汶川地震后实测残余变形的分布基本上吻合,进一步检验了本文所建立模型及相应数值方法的适用性。
[Abstract]:Excessive permanent deformation is often the main cause of earthquake damage of rockfill dams. It is very important to predict the seismic deformation of rockfill dam accurately. The equivalent viscoelastic-plastic model, which is widely used at present, has great experience in describing the deformation of rockfill under earthquake load, and the residual deformation caused by earthquake load can only be estimated roughly, which can be remedied by using the cyclic elastic-plastic model. On the basis of previous studies, the stress-strain law of rockfill under cyclic loading is summarized, a practical three-dimensional elastic-plastic cyclic constitutive model is established, and a numerical method based on this model is proposed. The dynamic calculation program of face rockfill dam based on open source finite element software OpenSees is developed. The research results obtained in this paper mainly include the following aspects: first, a three-dimensional elastic-plastic constitutive model which can reasonably reflect the stress-strain characteristics of rockfill under cyclic loading is established. Compared with the existing elastoplastic cyclic constitutive model, this model has the following obvious advantages: 1) A two-parameter three-dimensional nonlinear strength criterion based on the modified spatial sliding surface strength theory is proposed. The description of the strength of rockfill under complex cyclic loading is more simple and reasonable, and it can reflect the cumulative law of the strain of irreversible body under the action of bionic stress cycle, spherical stress cycle and both of them. It can reflect the hysteretic characteristic, hardening characteristic and strain accumulation characteristic of shear stress-strain relationship under cyclic shear load. In order to make the description of shear strain of rockfill more precise and reasonable under cyclic load, there are 11 model parameters with definite physical meaning, which can be obtained from the maximum shear modulus measured by vibration triaxial test. The conventional experimental results, such as modulus attenuation curve and residual deformation accumulation curve, make the model more practical. Secondly, the numerical realization method of the constitutive model is presented, and the user material subprogram based on open-source finite element software OpenSees and the auxiliary pre-and post-processing program for dynamic calculation of face rockfill dam are developed. A more efficient numerical modeling is realized. The validity of the program is tested by a series of calculation and comparative analysis of the two dimensional ideal dam model and the three dimensional homogeneous dam model. Thirdly, the vibration response and deformation law of Zipingpu high face rockfill dam are reappeared and revealed by three-dimensional dynamic elastic-plastic finite element analysis. The simulation results are basically consistent with the distribution of residual deformation measured after Wenchuan earthquake. The applicability of the proposed model and the corresponding numerical method is further tested.
【学位授予单位】：清华大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TV41

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