工业甘蔗渣-低碱生态水泥改良膨胀土边坡稳定性数值模拟分析

韦闻睿，郭炎波^*，陈天力，蒙法翼，黄巍，苏敏成，陈书卿，李磊

广西环保产业投资集团有限公司，广西 南宁  530200

摘要：为研究工业甘蔗渣（在膨胀土中的质量分数为1.2%）-低碱生态水泥（在膨胀土中的质量分数为7.0%）改良膨胀土边坡（以下简称改良膨胀土边坡）在降雨环境下的稳定性，分析其与未改良膨胀土边坡的差异，以及边坡稳定性与变形、渗流的内在联系，基于室内试验获得的土壤参数，采用数值模拟软件COMSOL Multiphysics进行大尺寸边坡降雨强度折减模拟分析，探究降雨过程中2种土质边坡有效饱和度、塑性应变、位移与边坡稳定性系数的变化规律。结果表明：1）连续降雨后，2种土质边坡的有效饱和度整体变化较小，改良膨胀土边坡的有效饱和度大于未改良膨胀土边坡；在仅考虑降雨影响条件下，边坡破坏时改良膨胀土边坡表层部分的有效饱和度大于未改良膨胀土边坡。2）在降雨条件下，未改良膨胀土边坡的塑性变形主要发生在坡脚，改良膨胀土边坡的塑性应变集中在坡顶，改良膨胀土边坡的塑性应变略大于未改良膨胀土边坡。3）降雨后，2种土质边坡的位移均发生在坡顶，未改良膨胀土边坡的位移约为改良膨胀土边坡的2倍；在相对较大的位移范围内，未改良膨胀土边坡受影响土体的面积更大，改良膨胀土边坡受影响范围仅在塑性变形周围50 m内，未改良膨胀土边坡的位移发育至坡脚处。4）考虑降雨强度折减法后，两种土质边坡的坡体内部均出现U型塑性应变区域，表层土体与深层土体发生相对滑动，未改良膨胀土边坡的塑性应变约为改良膨胀土边坡的3倍；未改良膨胀土边坡和改良膨胀土边坡的稳定性系数分别为1.12、1.14，未改良膨胀土边坡的最大位移约为改良膨胀土边坡的4倍。

关键词：膨胀土边坡；稳定性；数值模拟；有效饱和度；塑性应变

Numerical simulation analysis of the stability of expansive soil slopes improved by industrial bagasse-low-alkali ecological cement

WEI Wenrui, GUO Yanbo^*, CHEN Tianli, MENG Fayi, HUANG Wei, SU Mincheng, CHEN Shuqing, LI Lei

Guangxi Environmental Protection Industry Investment Group Co., Ltd., Nanning 530200, China

Abstract: To study the stability of industrial sugarcane residue (mass fraction of 1.2%)-low alkali ecological cement (mass fraction of 7.0%) improved expansive soil slopes (hereinafter referred to as improved expansive soil slopes) under rainfall conditions, this research analyzes the differences between improved and unimproved expansive soils slope, as well as the intrinsic relationship between slope stability, deformation, and seepage. Based on soil parameters obtained from laboratory tests, numerical simulation software COMSOL Multiphysics is used to conduct large-scale slope rainfall intensity reduction simulations to explore the changes in effective saturation, plastic strain, displacement, and slope stability coefficient of the two types of soil slopes during rainfall. The results show that: 1) After continuous rainfall, the overall change in effective saturation of the two types of soil slopes is small, with the effective saturation of the improved expansive soil slope greater than that of the unimproved expansive soil slope; under the condition of considering only the influence of rainfall, the effective saturation of the surface layer of the improved expansive soil slope at failure is greater than that of the unimproved expansive soil slope. 2) Under rainfall conditions, plastic deformation in the unimproved expansive soil slope mainly occurs at the toe, while the plastic strain in the improved expansive soil slope concentrates at the crest, with the plastic strain of the improved expansive soil slope slightly larger than that of the unimproved expansive soil slope. 3) After rainfall, displacements in both types of soil slopes occur at the crest, with the displacement of the unimproved expansive soil slope being about twice that of the improved expansive soil slope; within a relatively large displacement range, the area of affected soil in the unimproved expansive soil slope is larger, while the affected range of the improved expansive soil slope is limited to within 50 m around the plastic deformation, with the displacement of the unimproved expansive soil slope extending to the toe. 4) Considering the rainfall intensity reduction method, U-shaped plastic strain zones appear within both types of soil slopes, with relative sliding occurring between the surface soil and deep soil; the plastic strain in the unimproved expansive soil slope is about three times that of the improved expansive soil slope; the stability coefficients of the unimproved expansive soil slope and improved expansive soil slope are 1.12 and 1.14, respectively, with the maximum displacement of the unimproved expansive soil slope being about four times that of the improved expansive soil slope.

Keywords: expansive soil slope; stability; numerical simulation; effective saturation; plastic strain