基于应力场和变形场的边坡稳定性研究

发布时间：2018-06-28 18:51

本文选题：边坡 + 安全系数　；参考：《武汉大学》2016年博士论文

【摘要】：边坡的应力场和变形场与边坡稳定性有密切联系,如何有效地利用应力场和变形场去判断边坡的破坏模式并对其进行加固,具有重要的理论价值和工程意义。从理论分析、试验验证、数值计算、实际工程分析四个方面出发研究上述问题,得出以下主要结论：(1)通过边坡离心模型试验,研究了其变形特点,并对试验土样开展了三轴试验,建立了变模量弹塑性模型和Et-μt二重势面模型,认为数值方法基本可反映破坏前的试验结果,但要研究破坏的发生和发展的全过程,仍需更深入的研究。(2)根据应力场和变形场确定滑坡的破坏类型以及其最优加固位置。采用变模量强度折减法对边坡的应力场和变形场进行计算分析,通过数值计算结果表明：对于推移式滑坡,其上部的应力水平和位移高于下部；牵引式滑坡下部的应力水平和位移大于上部；而复合式滑坡,则是推移式滑坡和牵引式滑坡的组合。假设在边坡的不同位置设置抗滑桩,研究抗滑桩加固后的安全系数与应力场和变形场的关系,结果表明当抗滑桩设置在应力水平和变形场均较大的位置可获得最大安全系数。因此,推移式滑坡的最优加固位置是其上部,而牵引式滑坡的最优加固位置则是其下部,对于复合型滑坡其最优位置一般在边坡内应力水平和变形场都较大的位置。同样,采用锚索加固时,发现在高应力水平和大位移区域分配更多的加固荷载可以获得较好的加固效果。(3)比较不同破坏模式下强度折减法与传统整体极限平衡法的安全系数,发现推移式滑坡的两者结果较一致,而牵引式滑坡整体极限平衡法的结果大于强度折减法；牵引式滑坡的整体极限平衡法的安全系数可能是偏大的,尤其是存在较大的不均地质情况。(4)不同的破坏模式,边坡的位移模式也不一样,采用变模量强度折减法分析不同边坡破坏模式,总结得出：对于牵引式滑坡,其滑动破坏呈现“脆性”破坏的特征；而推移式滑坡在滑坡前在坡顶会有明显的位移预警,具有“塑性”破坏的特点。因此,边坡设计处理应避免产生牵引式破坏模式,宜设计成推移式破坏模式,就像钢筋混凝土梁的“适筋梁”那样,会在破坏前有明显的预警变形,减少灾害发生。
[Abstract]:The stress field and deformation field of the slope are closely related to the stability of the slope. How to use the stress field and the deformation field effectively to judge the failure mode of the slope and strengthen it has important theoretical value and engineering significance. The above problems are studied from four aspects: theoretical analysis, experimental verification, numerical calculation and practical engineering analysis. The main conclusions are as follows: (1) through the centrifugal model test of slope, the deformation characteristics are studied. Triaxial tests were carried out on the test soil samples, and the elastic plastic model of variable modulus and the Et- 渭 t potential surface model were established. It is considered that the numerical method can basically reflect the test results before failure, but the whole process of occurrence and development of failure should be studied. Further research is needed. (2) according to the stress field and deformation field, the failure type of landslide and its optimal reinforcement location are determined. The stress field and deformation field of the slope are calculated and analyzed by the variable modulus strength reduction method. The numerical results show that the stress level and displacement in the upper part of the slope are higher than those in the lower part; The stress level and displacement in the lower part of the traction landslide are greater than those in the upper part, while the composite landslide is the combination of the moving landslide and the traction landslide. Assuming that anti-slide pile is set in different position of slope, the relationship between safety factor, stress field and deformation field after reinforcement of anti-slide pile is studied. The results show that the maximum safety factor can be obtained when the anti-slide pile is located in the position where the stress level and deformation field are larger. Therefore, the optimal reinforcement position of the bedded landslide is its upper part, while the optimal reinforcement position of the traction landslide is its lower part. For the composite landslide, the optimal position is generally in the position where the stress level and deformation field of the slope are relatively large. In the same way, when using anchor cable to reinforce, it is found that more load distribution in high stress level and large displacement region can obtain better reinforcement effect. (3) comparing the safety coefficient of strength reduction method and traditional limit equilibrium method under different failure modes, It is found that the results of the two methods are consistent, while the results of the overall limit equilibrium method of the traction landslide are greater than those of the strength reduction method, and the safety factor of the overall limit equilibrium method of the traction landslide may be on the high side. In particular, there are large uneven geological conditions. (4) different failure modes and different displacement modes of slope are also different. The failure modes of different slopes are analyzed by variable modulus strength reduction method, and the following conclusions are obtained: for tractive landslides, The sliding failure shows the characteristics of "brittle" failure, while the bedded landslide has the characteristics of "plastic" failure and obvious displacement warning at the top of the slope before the landslide. Therefore, the slope design treatment should avoid the traction failure mode, and should be designed as the displacement failure mode, just like the reinforced concrete beam, there will be obvious early warning deformation before the failure, and the disaster will be reduced.
【学位授予单位】：武汉大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TU43

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