基于渗流场和应力场耦合作用的岸坡稳定性分析

发布时间：2018-02-25 05:13

本文关键词： 岸坡稳定极限平衡法耦合分析渗流场应力场　出处：《暨南大学》2015年硕士论文　论文类型：学位论文

【摘要】：库岸滑坡问题是水库蓄水诱发的灾害之一,随着大型水利工程的兴建,岸坡险情分布范围扩大,岸坡在水位变动下的稳定问题越来越受到学术界和工程界关注。目前,许多岸坡的研究工作中,渗流分析和应力分析是分开单独计算的,但是只要有水的地方,应力场和渗流场就会相互影响、相互作用,处于一种复杂的动态变化过程中,构成了流固耦合关系。本文在总结前人研究成果的基础上,基于极限平衡理论和渗流场-应力场耦合理论对一水库近坝区的一实际古滑坡进行了稳定性分析。首先采用极限平衡法进行稳定分析,然后基于渗流场-应力场耦合理论建立数学模型并求得其有限元解,通过对各种工况下的岸坡稳定进行基于耦合理论的数值分析,研究水位变动下岸坡的稳定状态,并根据分析结果提出了加固方案。计算结果表明,加固后的边坡可以应对各种设计工况,满足稳定要求。论文主要研究内容与成果如下:(1)水库第一次蓄水条件下岸坡稳定性预测。水库蓄水会提高滑坡体内的地下水位,改变原有的渗流场,随着渗流区域增大,沿渗流方向的动水压力将增大岸坡的下滑力,又因为岸坡坡脚被淹没,水下土体抗剪强度衰减,岸坡的抗滑力将被削减,使得岸坡前缘存在滑动危险。本文分析结果显示,岸坡前缘在水位上升过程中产生了趋向水库方向的较大位移,形成明显的滑动区域,坡体前缘局部失稳。边坡整体安全系数也随水位上升明显下降到低于规范要求。根据计算结果,可知岸坡在水库第一次蓄水过程中将处于不稳定状态。(2)坡脚滑动对岸坡稳定性的影响分析。分析表明,水位上升导致坡脚局部滑动后,岸坡原来的平衡状态被打破,应力场将重新分布,坡体中上部因失去坡脚土体的支撑可能沿着古滑动带产生下滑,存在复活的危险。本文分析结果揭示了水位上升过程中岸坡中部、下部古滑动带处剪切变形区域扩大,贯通坡脚,坡体有沿着古滑动带向水库方向滑动的趋势,岸坡整体安全系数因前缘坡脚失稳从1.759降至0.992。由此可知,若岸坡前缘失稳,中上部坡体失去支撑而沿古滑动带整体下滑,将形成牵引式滑坡。(3)坡脚加固对岸坡稳定性的作用。为防止岸坡牵引式滑坡的形成,本文建立了对岸坡坡脚进行压重加固的数值分析模型,计算结果表明,无论是水库蓄水还是水位骤降,岸坡的位移量都明显减少,坡脚没有形成滑动区域,也没有局部滑动的趋势。虽然滑坡体沿古滑动带有局部、少量的剪切变形带,但对于坡体整体稳定、坡体前缘局部稳定都没有造成明显的不良影响。由此可知,坡脚加固的措施能够有效地增强坡脚材料的抗剪强度,提升坡脚抗滑力,从而遏制牵引式滑坡机制的形成,加固后岸坡处于稳定状态。(4)基于变形监测的边坡预警系统研究。由于实测元件方面的制约,目前边坡监测的内容一般是针对监测点位移,很少有针对材料强度进行的监测,但是边坡稳定性的判别模型和方法一般是基于材料的强度,这就存在一个明显的不衔接。针对这一现状,本文从简单适用的原则出发,以现行规范推荐的极限平衡法为基础,初步建立了考虑强度-应变软化关系的边坡稳定预警系统。然后以一简单边坡为例给出了基于变形监测资料的稳定预警流程。在此基础上,本文进一步结合有限元技术对此预警系统的平台进行了扩充,使之可容纳更多如流固耦合的岩土专业研究成果,有望形成基于变形监测和强度-应变软化理论的预警系统,以便更适用于水库管理和边坡滑动防治。
[Abstract]:Landslide is one of the disasters induced by reservoir impounding, with large-scale water conservancy engineering, the distribution range of the slope stability problem of slope in danger of expansion, water level changes under more and more attention in academia and engineering. At present, many research works of slope, seepage flow analysis and stress analysis are calculated separately however, as long as there is water, stress field and seepage field will influence each other, interaction is a complex dynamic process, a coupling relation. Based on the summary of previous research results, the limit equilibrium theory and the seepage field and stress field coupling theory of a reservoir near the actual landslide stability is analyzed firstly. Based on the limit equilibrium method for stability analysis, and then based on the seepage and stress field coupling theory to establish the mathematical model and calculate its finite element solution, This paper makes a numerical analysis based on the coupling theory of the slope stability under various conditions, the research of water level change of stable state of slope, and the reinforcement program is put forward according to the analysis results. The calculation results show that the slope after reinforcement can deal with all kinds of design condition, meet the stability requirements. The main research contents and results are as follows: (1) reservoir the first impoundment conditions. The slope stability prediction of reservoir will increase the groundwater level of the landslide, the change of seepage field of the original, with the seepage area increases, the sliding force along the flow direction of the hydrodynamic pressure will increase the slope, and slope toe because flooded, the shear strength of soil under water attenuation, sliding force will be anti cut slope, the slope leading edge. In this paper, the existence of sliding risk analysis results show that the larger displacement tends to the direction of the reservoir during the rise in water level in front of slope, the formation of Ming Dynasty The slide area significantly, the leading edge of the slope of local instability. The safety factor of the whole slope also increased significantly with the water level drops below the specification. According to the calculation results, the slope in the reservoir during the first impoundment in an unstable state. (2) analysis of influence on slope sliding slope. Analysis shows that the water level rising slope local sliding, slope breaks the equilibrium state, the stress field will redistribute, the upper slope due to loss of slope soil may support along the ancient sliding zone have declined, there raised the danger. The results revealed that the central bank water level rise, the lower sliding zone ancient shear deformation zone expands through the foot of the slope, the slope along the sliding direction of the reservoir to the ancient sliding trend, the overall safety factor of slope instability due to the front foot from 1.759 to 0.992. so that, if the front of slope In the upper part of the slope instability, loss of support along the ancient sliding zone overall decline, will form a retrogressive landslide. (3) to reinforce the slope stability of the slope. In order to prevent the slope of retrogressive landslide formation, the numerical analysis model is established in this paper. On the other side slope toe pressure heavy reinforcement, the calculation results show that both the the reservoir water level falls or, the displacement of slope are significantly reduced, the slope has not formed sliding region, no local sliding trend. Although the landslide along the ancient slide with local small, shear deformation zone, but for the overall stability of the slope, slope local stability did not cause significant adverse effects from this. The slope reinforcement measures, can effectively enhance the shear strength of slope material, enhance slope anti slide force, in order to prevent the formation of the traction type landslide mechanism, the slope is in a stable state after reinforcement. (4) based on deformation Study on slope monitoring early warning system. Due to the restriction of actual components, the slope monitoring content is general for displacement monitoring points for monitoring of material strength is little, but the slope stability model and method is generally based on the strength of the material, there is not a clear convergence. In view of this situation this paper, from the simple application of the principle of limit equilibrium method to the current standard recommended as the foundation, established the early warning system of slope stability considering the strength and strain softening relationship. Then a simple slope for example gives the stability of deformation monitoring data based on the early warning process. On this basis, this paper further combined with the finite element technique this early warning system platform is extended, which can accommodate more fluid solid coupling of geotechnical professional research, is expected to form based on the deformation monitoring and intensity should be The early warning system of the theory of variable softening is more suitable for the management of reservoir and the prevention and control of slope sliding.

【学位授予单位】：暨南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TV223

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