黄土填方高边坡稳定性研究

【作者】 宋焱勋；

【导师】 张骏； 曹家泉；

【作者基本信息】 长安大学 ， 地质工程， 2006， 硕士

【摘要】 在对凤凰山倒班基地黄土填土高陡边坡稳定性进行定性分析评价的基础上,结合极限平衡法和数值模拟方法,对该边坡的稳定性状态进行了研究,根据稳定性的研究结果,提出了治理该高陡边坡的建议方案。首先,根据凤凰山倒班基地黄土填土高陡边坡的变形破坏特征,从定性的角度对其变形破坏机制进行了全面探讨和深入分析。研究发现,凤凰山倒班基地高陡填方边坡变形显著,上部平台及坡体上裂缝发育,局部并出现有错动现象,其最大错动高差达1m;其上部的裂缝距离变压器近,裂缝的发展已经造成了变压器围墙墙体和栏杆的拉裂。其变形破坏主要有以下几种形式:坡面冲刷;崩(滑)塌;泥流和蠕滑-拉裂式变形破坏;坡体湿陷变形。变形破坏的影响因素主要为填土的结构与性质、水、地形地貌及人工不合理堆载等,其中填土结构松散和水的软化作用在起主导作用。其次,利用圆弧法、裂隙法、及改进裂隙法对凤凰山倒班基地黄土填土高陡边坡进行了稳定性计算,对改进裂隙法最危险滑面搜索按复形调优法进行优化计算,使搜索机时大大缩小,很大程度上提高了计算速度。经过对计算结果的分析发现:凤凰山倒班基地高陡填方边坡在天然状态下整体稳定,坡顶至坡中间部分处于极限平衡状态;在饱水状态下,该边坡整体处于极限平衡状态,坡顶至坡中间部分破坏。再次,采用二维有限元和三维有限差分对凤凰山倒班基地黄土填土高陡边坡进行了数值模拟研究,结果表明:在天然状态下,凤凰山倒班基地高陡填方边坡中的应力场表现为总体上的自重应力场特征。坡体的水平应力都是以压应力为主,而剪应力集中范围在坡顶以下20～25m的范围,对于竖向应力,其大小及分布特征在开挖前后则没有明显变化,都是以压应力为主,并随着深度的加深而逐渐增大。向坡体后缘方向逐渐减小。竖向应变变化则具有明显的规律性,表现为在坡体中随着深度的加深,竖向应变量先增大,后减小,最后又逐渐增大的现象,分析表明主要是岩性的差异导致了坡体不同部位的不同变形特征,这些结果验证了极限平衡法的相关计算结果。最后,根据本文的定性分析,定量评价和数值模拟方法对该边坡的稳定性状态进行了研究的结果,就凤凰山倒班基地黄土填土高陡边坡防治措施提出了针对性建议,从而为该边坡今后的治理打下了可靠的理论基础。更多还原

【Abstract】 The stability of stuffing loess high slope in Phoenix Mountain shift base was studied based on its qualitative analysis, on the limiting equilibrium method and on numerical simulation. According to the study result, the control measures for this slope were suggested.Firstly, the deformation and destruction mechanism of stuffing loess high slope in Phoenix Mountain shift base were analyzed completely and deeply in qualitative analysis based on its deformation and destruction feature. The result shows that the deformation in this slope is remarkable. The fissures in the upper slope terrace and slope mass are well-development, part of this slope can see faulted phenomenon, the maximum height difference of which over 1m; the upper fissures are near the voltage transformer, and the development of them have made the pull-apparition of voltage transformer and the handrail. The deformation forms of the slope are: slope wash, collapse (slumping), mudflow, creep slide- pull apparition and collapsibility, etc. the main influence factors of deformation are: the structures and properties of filling soil, water, topography and morphology and the people’s unreasonable pole up, etc. the pill soil and the water soften among of which take the leading function.Then, the stability of stuffing loess high slope in Phoenix Mountain shift base was computed by circular arc method, crack method and improved crack method, the most dangerous face was searched for by improved crack method which was optimized by composite optimal method, so, the computed time was reduced greatly, and the computed speed was increased in a great condition. The computation results was showed that: on the natural condition , this high slope is steady in whole and is limited equilibrium in the part from slope top to the slope middle; on the saturation condition, this slope is limited equilibrium in whole and destruction in the part from slope top to the slope middle.Then, the stuffing loess high slope in Phoenix Mountain shift base was numerical simulated by two-dimension limited unit and three-dimension limited difference. The result indicates that the stress field shows the features of dead-weight in total. The horizontal stress of this slope mass is press stress mainly, the shear stress is concentrated in the place of the range of 20-25 meter under the top slope. Toward the vertical stress, there have not obvious change in size and distribution, and mainly is press stress, and the greater the deeper, the smaller the backer of the slope mass. The change of vertical strain has obvious regular patterns, it is see that with the deeper of the slope mass, the vertical strain reduce firstly, the increase. It is the difference of lithology that leads to the difference character in different part. These results prove the result of limited equilibrium.Lastly, the control measures was suggested base on the qualitative analysis, quantitative analysis and numerical simulation analysis, and the study base was established reliability and theoretically.更多还原