折线滑动模式下堆积层滑坡稳定性研究

发布时间：2018-03-28 06:42

  本文选题：折线滑动模式　切入点：堆积层滑坡　出处：《湘潭大学》2017年硕士论文

【摘要】：堆积层滑坡是滑坡地质灾害中分布最为广泛的一类,折线滑动是其一种基本的滑移失稳形式。在折线滑面滑坡的稳定性分析和治理研究方法中应用最为广泛的是我国独创的不平衡推力法(ITFM)。该法不仅考虑了土条界面上剪力的影响,还可以获得任意形状滑动面在复杂荷载作用下的滑坡推力数值,计算简洁,适用于任意形状的滑裂面,不需要经过迭代计算而给出能够满足一般工程需要的稳定系数值,并且能够为滑坡治理提供设计推力值。但此法不足之处是只适用于已经完全滑动的边坡,且在滑块倾角变化过大时使稳定系数计算结果偏大、滑坡推力值偏小。因此,为了研究正处于发展变形中的滑坡在折线滑动模式下的稳定性规律,本文依据极限平衡法和有限元强度折减法(SRFEM)基本理论,以新晃县某滑坡工程实例为研究对象,分析边坡在不同工况下的稳定性情况以及应力—应变规律。主要研究成果如下:(1)改进了不平衡推力法的取值方法,该法同时考虑边坡岩土体峰值强度和残余抗剪强度指标,其值由滑块的稳定状态决定,而非定值。当Fi(29)1取值ic、i?(土体峰值抗剪强度);Fi(27)1时,为cic、ci?(土体残余抗剪强度)。(2)根据现场勘察资料,综合判定新晃县某滑坡的失稳模式为中型牵引式顺层滑坡;分析了滑坡形成机理,认为大气强降水则是诱因,地形条件(处于沟谷岸坡)和土层条件(土质松散、基岩面破碎)是滑坡形成的内因,人类工程活动对植被的破坏和坡脚开挖则是外因。(3)应用ABAQUS软件模拟了滑坡在自重工况下的整个失稳过程,计算得到的塑性区形态与现场实测滑动面基本一致,判定滑动面位置为岩土交界面(强风化岩与中风化岩界面),并以此建立了不平衡推力法计算模型。(4)采用两种取值方法分别计算了自重和暴雨工况下Ⅱ号滑坡稳定系数和滑坡推力数值,发现:传统取值法在分别取值为峰值强度与残余强度时,计算结果相差很大,约为28.6%~43.4%;但后者与改进法计算结果较为接近,差值约为2.58%~17.5%;改进取值法,考虑了边坡在变形破坏过程中岩土体强度衰减,原理与强度折减法相近,计算结果相较传统方法更为可靠,接近工程实际。(5)根据改进取值法所得滑坡推力设计的抗滑桩钢筋消耗相比传统取值方法可减少约11.5%;提出了预应力锚索抗滑桩+锚杆框格梁的滑坡治理方案,可有效阻断滑坡塑性区的发展和控制坡体变形,处治后的Fs(28)1.76,符合规范要求。
[Abstract]:The accumulation layer landslide is the most widely distributed type of landslide geological hazard. Broken line sliding is one of the basic slip instability forms. The most widely used method for stability analysis and treatment of broken slip surface landslide is the unbalanced thrust method (ITFMN), which has been created in China. This method not only takes into account the influence of shear force on the interface of soil strip, but also the effect of shear force on the interface of soil strip. The landslide thrust value of any shape sliding surface under complex load can also be obtained. The calculation is simple and suitable for any shape slide crack surface. The stability coefficient value which can satisfy the general engineering needs can be obtained without iterative calculation. And it can provide the design thrust value for landslide treatment. However, this method is only suitable for the slope which has been completely sliding, and when the slope angle of the slide block is too large, the calculation result of the stability factor is too large and the thrust value of the landslide is too small. In order to study the stability law of landslide in developing deformation under the broken line sliding mode, based on the basic theory of limit equilibrium method and finite element strength reduction method (SRFEMM), this paper takes a landslide engineering example in Xinhuang County as the research object. The stability and stress-strain law of slope under different working conditions are analyzed. The main research results are as follows: (1) the unbalance thrust method is improved, which takes into account both peak strength and residual shear strength index of slope and soil mass. The value is determined by the stable state of the slider, not by the fixed value. (peak shear strength of soil is Ciccic? (residual shear strength of soil mass) according to the field investigation data, the instability model of a landslide in Xinhuang County is determined to be a medium type towed bedding landslide, and the formation mechanism of landslide is analyzed, and it is considered that heavy atmospheric precipitation is the inducement. The landform condition (at the gully bank slope) and the soil layer condition (the soil quality is loose, the bedrock surface is broken) are the internal causes of the landslide, The damage of vegetation caused by human engineering activities and excavation of slope foot are external factors. (3) the whole instability process of landslide under deadweight condition is simulated by using ABAQUS software. The calculated plastic zone shape is basically consistent with the field measured sliding surface. The position of sliding surface is determined to be the interface between rock and soil (strong weathered rock and medium weathered rock interface). Based on this, the calculation model of unbalanced thrust method is established. Two methods are used to calculate the stability of landslide 鈪，

本文编号：1675185