文章编号：1004－5422(2021)04－0424－06

DOI:10.3969/j.issn.1004-5422.2021.04.015

某公路边坡预开挖稳定性发展趋势及防治方案

曾琇舒

（核工业西南勘察设计研究院  交通市政院，四川  成都  610042）

摘   要：以大渡河沿线某复建高速公路工程为背景，选取一处待开挖土质斜坡为研究对象，根据复建线路设计方案以及研究区地质环境条件，采用大型直剪试验对第四系崩坡积碎石土天然、饱和力学特性进行测试，并采用GeoStudio软件中的slope模块进行天然、降雨工况下稳定性分析.主要结论：①斜坡第四系覆盖层为崩坡积碎石土，其饱水前后力学强度变化显著，剪应力-剪切位移曲线由应变软化型逐渐转为应变硬化型，饱水后土体内聚力降低46.3%，内摩擦角降低12.4%，内聚力受孔隙水影响程度远高于内摩擦角；②开挖前斜坡整体处于稳定状态，降雨对其影响程度有限，开挖后形成临空面，坡体稳定性急剧下降，处于欠稳定或失稳临界状态，降雨的叠加使其发生失稳破坏；③根据开挖前后边坡稳定性发展趋势，结合工程安全、生态环境等因素，同时考虑灾害与生态问题，提出5点防治建议.

关键词：碎石土；开挖边坡；稳定性系数；防治方案

中图分类号：U416.1+4            文献标识码：A

Development of Pre-Excavation Stability of A Highway Slope and Suggestions on Prevention Scheme

ZENG Xiushu

（Nuclear Industry Southwest Geotechnical Investigation & Design Institute Co.,Ltd.，Chengdu 610042，China）

Abstract：Based on a reconstruction expressway project along Dadu River,a soil slope to be excavated is selected as the research object.According to the design scheme of the reconstruction line and the geological environment conditions of the study area,a largescale direct shear test is used to test the natural and saturated mechanical properties of quaternary colluvial slope gravel soil,and the slope module of GeoStudio software is used to test the natural and saturated mechanical properties stability analysis under rainfall condition.The main conclusions are as follows: ①the quaternary overburden of the slope is soil,and its mechanical strength changes significantly before and after water saturation.The shear stress shear displacement curve changes from strain softening type to strain hardening type gradually.After water saturation,the cohesion of the soil decreases by 46.3%,and the internal friction angle decreases by 12.4%;②Before excavation,the whole slope is either in a stable state,and the influence of rainfall is limited.After excavation,the free face is formed,and the slope stability drops sharply,which is either in a critical state of instability or in a state of instability;③according to the development trend of slope stability before and after excavation,combined with engineering safety,ecological environment and other factors,five prevention suggestions are put forward,which involves the consideration of the disaster and ecological problems at the same time.

Key words：gravel soil;excavation slope;stability coefficient;prevention scheme