分步开挖卸荷作用下软硬岩互层边坡的稳定性分析

发布时间：2018-05-27 19:13

本文选题：开挖卸荷 + 软硬岩互层边坡　；参考：《科学技术与工程》2016年29期

【摘要】：以沪蓉高速公路某软硬互层边坡为例,基于开挖卸荷理论,采用FLAC3D软件进行数值模拟,研究分步开挖卸荷作用对软硬互层边坡稳定性的影响规律。结果表明:最大不平衡力、最大水平位移值、剪应变最大值随开挖步数的增加累积增大,最大值出现在开挖卸荷面软弱夹层剪出口位置,与开挖量呈正相关关系;每步开挖后瞬间会产生最大不平衡力"尖点",然后逐渐减小接近于零,边坡平衡;塑性区主要分布在软弱夹层位置,拉应力区分布于开挖卸荷面附近以及整体边坡的坡顶面附近20 m以内,且总体拉应力不大,低于灰岩卸荷后的抗拉强度;基于卸荷理论计算得到每步开挖后边坡的稳定性系数比不考虑卸荷对边坡岩体劣化作用的稳定性系数分别降低了0.07、0.08、0.102、0.106。综合分析得出软硬岩互层边坡稳定性的关键问题是开挖卸荷对软弱夹层力学性能的影响以及边坡面附近的拉应力区,开挖卸荷作用对岩体物理力学性能的劣化程度直接决定着边坡的稳定性。
[Abstract]:Taking a soft and hard interbedded slope of Hurong Expressway as an example, based on excavation unloading theory, numerical simulation is carried out with FLAC3D software to study the influence of step excavation unloading on the stability of soft and hard interbedded slope. The results show that the maximum disequilibrium force, the maximum horizontal displacement and the maximum shear strain increase with the increase of the excavation step, and the maximum value appears at the exit of the soft intercalation shear on the excavating unloading surface, which is positively correlated with the excavation quantity. The maximum unbalance force "tip" will be produced immediately after each step excavation, and then gradually reduce to zero, the slope is balanced, and the plastic zone is mainly distributed in the weak intercalation. The tensile stress zone is distributed within 20 m near the excavated unloading surface and the top surface of the whole slope, and the overall tensile stress is not large, which is lower than the tensile strength of limestone after unloading. Based on the unloading theory, the stability coefficient of the slope after excavation is reduced by 0.07 / 0.080.102 / 0.106, respectively, compared with the failure to consider the degradation of slope rock mass by unloading. Comprehensive analysis shows that the key problem of the stability of soft and hard rock interbedded slope is the influence of excavation and unloading on the mechanical properties of the soft interlayer and the tensile stress region near the slope surface. The slope stability is directly determined by the deterioration of rock mass physical and mechanical properties due to excavation unloading.
【作者单位】：中国地质大学工程学院;中交第二公路勘察设计研究院有限公司;湖北工业大学;
【基金】：国家自然科学基金项目资助(41172281) 中央高校基金科研业务费专项资金项目(摇篮人才计划CUGL100413) 特色学科团队CUG090104)资助
【分类号】：U416.14

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