岩质边坡开挖卸荷岩体参数特征分析  

Parametric Analysis of Rock Mass during Excavation and Unloading of Rock Slope

作　　者：杜威 陈兴周[1] 陈莉丽 江海 王文瑞 DU Wei;CHEN Xingzhou;CHEN Lili;JIANG Hai;WANG Wenrui(Department of Architecture and Civil Engineering,Xi′an University of Science and Technology,Xi′an 710054,China)

机构地区：[1]西安科技大学建筑与土木工程学院,陕西西安710054

出　　处：《防灾减灾工程学报》2023年第3期596-603,共8页Journal of Disaster Prevention and Mitigation Engineering

基　　金：国家自然科学基金项目(51979218,U1965107);陕西省自然科学基金项目(2018JM5118)资助。

摘　　要：岩质边坡的开挖卸荷过程直接决定工程施工的安全性,边坡变形特征分析及有效数值模拟方法的选取至关重要。基于卸荷岩体力学理论与方法,开展红砂岩试件的室内常规三轴与三轴卸荷试验,分析其变形特征、卸荷量与变形模量之间的关系以及强度参数的变化规律,结合有限单元法构建考虑卸荷作用的算例模型,探究考虑边坡开挖卸荷作用所引起的应力释放后的岩体劣化分区问题,以及边坡动态开挖卸荷下的变形分析。研究结果表明:①当卸荷量达70%和临近破坏时,其变形模量分别降低了10%和50%左右;②岩样卸荷力学状态下粘聚力有所降低,内摩擦角有所增高;③依据边坡初始应力场与开挖后应力场的对比分析从而确定强、弱卸荷影响区,算例模型表明考虑卸荷作用后水平位移净增量计算结果为不考虑卸荷作用计算结果的4倍左右,且其分步开挖支护效果显著,计算结果更加符合工程实际。研究成果可对边坡岩体开挖卸荷数值计算提供一定的指导意义。The excavation and unloading process of a rock slope directly determines the safety of engineering construction,so it is very important to analyze the deformation characteristics of slopes and establish an effective numerical simulation method.Based on the unloading rock mechanics theory and method,laboratory conventional triaxial and triaxial unloading tests were carried out on red sandstone specimens to analyze the deformation characteristics,the relationship between the unloading amount and deformation modulus,and the variation law of strength parameters.In addition,a numerical model that considers the unloading effect was constructed by combining the finite element method.This paper explores the issues of rock mass deterioration partitioning,considering the stress release caused by slope excavation unloading and the deformation analysis of slopes under dynamic excavation unloading.The results show that:(1)When the unloading amount reaches 70%and near failure,the deformation modulus decreases by approximately 10%and 50%,respectively;(2)Under unloading mechanical conditions,the cohesion of rock samples decreases and the internal friction angle increases;(3)By comparing the initial stress field and the stress field after excavation of the slope,the strong and weak unloading zones can be identified.The example model shows that the net calculation results of horizontal displacement increment after considering unloading effect are 4 times the results without considering the unloading effect,and the step-by-step excavation supporting effect is remarkable.The calculation results closely aligns with practical engineering.The research results can provide some guidance for the simulation of slope rock mass excavation unloading.

关 键 词：岩质边坡 卸荷试验 参数特征 数值计算 变形分析 

分 类 号：TU452[建筑科学—岩土工程]