基于ABAQUS流固耦合理论的库岸滑坡稳定性分析

【作者】 张欣；

【导师】 李术才； 丁秀丽；

【作者基本信息】 山东大学 ， 岩土与结构工程， 2005， 硕士

【摘要】 我国是一个地质灾害较多的国家,其中滑坡灾害占有较大比例。尤其是随着我国水利建设的大力兴建,时常有库岸滑坡发生失稳,对社会和人民造成严重威胁。水的渗透会严重影响滑坡的稳定性。实际上,只要有水存在的地方,应立场和渗硫场就会相互影响、相互作用,处于一种复杂的动态变化过程中,构成流固耦合关系。 本论文通过对耦合作用进行实质性分析,得出应力场合渗透场相互作用的机理:一方面,应立场的改变会影响土体渗透系数,从而影响渗流场;另一方面,渗流场通过改变水荷载来影响应立场。根据岩土体骨架的平衡方程和虚功原理建立应力场平衡方程。根据地下水的连续方程和变分原理建立渗流场微分方程。 应力场平衡方程和渗流场微分方程共同组成流固耦合问题的控制方程组。该方程组通常为非线性方程组,论文借助国际大型有限元软件ABAQUS进行了滑坡体内流固耦合的计算,继而对滑坡稳定性作了定量评价。 滑体本构关系具有高度的非线性,数值计算中可采用Duncan-Chang本构模型来模拟。本文以ABAQUS有限元软件为开发平台,提出了Duncan-Chang本构模型的开发思路和实现步骤,完成了模块的编程,并且依据常规三轴试验数据对开发的程序进行了一系列严格验证。结果证明开发是成功的。 茅坪滑坡是清江隔河岩水库库区一个十分典型和重要的大型古滑坡体,具有多级、多期次的滑动特征。该滑坡一旦失稳,必将产生严重后果。论文对茅坪滑坡体地质特征及监测资料进行研究,对滑坡体的稳定性作了定性分析。另外,通过对滑坡的数值分析计算,对滑坡稳定可靠度作了定量分析。结果表明:在天然水位下,滑坡中的塑性区范围较有限,尚难危及滑坡的整体稳定,但滑坡后缘附近水力梯度较大,渗流力较大,使该位置局部出现了拉应力,导致滑坡后缘稳定性较差。当水位急剧上升时,在斜坡前缘和后缘都出现了塑性区,滑坡整体稳定性降低。尤其是滑坡前缘稳定性变差,有局部失稳的可能性。 本文的工作对滑坡稳定性分析、流固耦合分析具有积极作用,而且本文提出的模拟方法、求解技术和开发思路对水工结构和岩土工程及其他工程领域的数值仿真研究也具有广泛的借鉴意义。更多还原

【Abstract】 There are some geological disastrous such as landslide in our country. Specially with the great scale of constructions for water resources, more and more landslides becomes unstable, which brings serious endanger to society and people. The reason is that when water permeates into landslides, it always weaken the stability of landslides. In fact, if there is any water, stress field and seepage field will affect each other, will be in a coupling dynamic drift situation and form a coupling relation.On the basis of material analysis to coupling effect, the author reachs the action mechanism between the stress field and the seepage field: first, the change of stress field can make influence to permeation parameter, then to the seepage field. Another, the seepage field can also make influence to stress field throw changing the water load. Based on balancing equation of framework of rock and soil and the principle of virtual work, the stress balancing equation can be acquired. Based on the continuity equation of ground water and the variation principle, the seepage differential equation can be acquired.The above two equations form the control equations which usually is a nonlinear equations. The dissertation computed the coupling problem of seepage and stress, and qualitive evaluate the stability of landslide.The upper part of landslide has high nonlinear character, we can use Duncan-Chang constitutive to simulate it. Choosing ABAQUS software as the high level development platform, the redevelopment procedures to add Duncan-Chang constitutive model were described and were compiled to codes. Some numerical verification were then examined strictly. According to the data of typical conventional triaxial compression tests, the verifications show that the redevelopment is successful.Maoping Landslide, one of the most typical and important large-scale recur landslide in the head-pond of Geheygan reservoir in Qingjiang River, has multilevel and repetitious sliding characters. Once the Maoping slope becomes instable, disastrous destroy can be caused. This dissertation analyses the geological characteristics and monitoring data of Maoping Landslide comprehensively, and make qualitive evaluation on the influence of water to landslide stability. In addition, according to the numerical calculation on landslides, the author make quantitative evaluation under twosituations: the natural reservoir water level and rapidly ascend reservoir water level. The simulating result indicates: for the first situation, the plastic zone is limited and can’t endanger the stability of the slope. But there is a tension area, and the ground water surface is a convex surface towards the slope face and the gradient is high near the slope back edge. And when water level ascends higher, the plastic zone also present at shallow zone near the slope front and back edges. And the stability becomes worse, even at the front edge.All the schemes proposed in this thesis have strong utility to stability analysis and seepage-stress coupling analysis, and are cable of reference to numerical simulation research for geo-engineering, hydropower structures and other engineering fields.更多还原