降雨作用下红黏土边坡的变形及现场剪切试验研究

The deformation and field shear test research of red clay slope under rainfall

摘要

边坡土体的变形特征和抗剪强度是边坡稳定性分析的重要依据。为研究降雨作用下红黏土边坡的变形特征和抗剪强度变化规律，以实际红黏土边坡工程为例，考虑降雨作用对边坡土体变形和抗剪强度的影响，通过对该边坡典型钻孔的侧向变形监测，得到了红黏土边坡的蠕变特征，同时对红黏土边坡的3组坡前试样和3组坡体试样进行现场剪切试验。结果表明：监测期内，红黏土边坡相同钻孔深度的侧向变形随降雨作用入渗逐渐增大，同一钻孔土层的侧向变形随钻孔深度的增大而减小，在土层岩层过渡区存在拐点急剧下降特征，最后降低至零；边坡土体的剪应力-剪切位移关系曲线按“弹性变形、屈服变形、硬化变形和破坏变形”四阶段发展变化，出现了明显的峰值强度和稳定的残余强度，具有显著的应力-应变软化特征；给出了坡前试样、坡体试样的峰值强度和残余强度经验模型，并得到了坡前土体的抗剪强度指标经验值c_f=38.760 kPa、φ_f=15.9°、c_fr=34.577 kPa、φ_fr=12.6°,坡体土体的抗剪强度指标经验值c_f=33.522 kPa、φ_f=10.2°、c_fr=30.234 kPa、φ_fr=9.5°。研究成果可为红黏土边坡的稳定性分析、确定抗剪强度参数及类似工程建设提供理论与数据参考。

Abstract

The deformation characteristics and shear strength of slope soil is an important basis for slope stability analysis. In order to study the deformation characteristics and shear strength of laterite clay slope under rainfall, the actual red clay slope engineering is taken as an example, considering the influence of rainfall on the deformation and shear strength of the slope soil, and the creep characteristics of the red clay slope are obtained through the lateral deformation monitoring of the typical borehole of the slope.Field shear tests on three groups of pre-slope samples and three groups of slope samples of the laterite clay slope are conducted. The results show that during the monitoring period, the lateral deformation of the red clay slope at the same borehole depth gradually increases with the infiltration of rainfall, and the lateral deformation of the same borehole soil layer decreases with the increase of borehole depth. The shear stress-shear displacement relationship curve of slope soil develops and changes according to the four stages of "elastic deformation, yield deformation, hardening deformation and failure deformation" has significant stress-strain softening characteristics, and there are obvious peak strength and stable residual strength. The empirical model of the peak and residual strength of the pre-slope specimen has been provided and the slope specimen and the empirical shear strength index of the pre-slope soil body are given as c_f=38.760 kPa、φ_f=15.9°、c_fr=34.577 kPa、φ_fr=12.6°, and the empirical values of shear strength index of soil body of slope body c_f=33.522 kPa、φ_f=10.2°, and c_fr=30.234 kPa、φ_fr=9.5°. The research result can provide theoretical and data reference for the stability analysis of red clay slopes, determination of shear strength parameters and similar engineering construction.

关键词

边坡工程 / 红黏土 / 降雨作用 / 侧向变形 / 抗剪强度 / 现场剪切试验

Key words

slope engineering / red clay / rainfall action / lateral deformation / shear strength / field shear tests

Author summay

何 飞(1981—), 男, 高级工程师, 硕士, 主要从事边坡与地基的设计、检测和加固等方面的研究工作。E-mail: [e-mail]

基金资助

国家自然科学基金项目(52438004)

贵州省科技计划项目(黔科合支撑[2022]一般237)