不同降雨强度下红黏土边坡干湿循环试验研究
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摘要
干湿循环过程中红黏土边坡力学参数发生了变化,红黏土边坡破坏特征和机理与一般土质边坡不同。以贵州红黏土为研究对象,采用浴霸–人工降雨模拟干湿循环,在室内制备了较大尺寸边坡模型,同时在边坡内部不同位置埋设含水率、孔隙水压力和温度传感器,分析了干湿循环下红黏土边坡力学参数演变规律和破坏机理。研究结果表明,随着深度增加,边坡土体含水率受降雨强度影响逐渐减弱,表层含水率受降雨强度影响明显。干燥期含水率呈现先增加后减小的现象。同一降雨强度下,坡脚含水率最大,其次为坡面、坡肩,最后为坡顶。表层孔隙水压力在降雨、渗透期上升,干燥期降低。降雨强度越大,温度变化幅度越大。随深度增加,边坡温度变化幅度逐渐减小。坡脚温度变化幅度较其他部位大。边坡破坏特征由溅蚀→面蚀→片蚀→裂缝→冲沟,未见明显的滑动面。
The mechanical parameters of red clay slopes change during the wetting-drying cycles. The failure characteristics and mechanism of the red clay slopes are different from those of the general soil slopes. For the Guizhou red clay, the bath heater-artificial rainfall-simulated wetting-drying cycles are used to prepare a large-scale slope model. The moisture content,pore water pressure and temperature sensors are buried at different positions inside the slope. The evolution law and mechanism of the mechanical parameters of red clay slopes under circulation are analyzed. The results show that with the increase of depth,the soil moisture content of the slope is gradually weakened by the rainfall intensity, and the surface moisture content is obviously affected by the rainfall intensity. The moisture content during the drying period increases first and then decreases.Under the same rainfall intensity, the moisture content at the slope toe is the largest, followed by the slope surface, the slope shoulder, and finally the slope top. The surface pore water pressure increases during rainfall and osmosis, and decreases during drying. The greater the rainfall intensity, the greater the temperature change. As the depth increases, the temperature change of the slope gradually decreases. The temperature at the slope toe changes more than that at other parts. The failure characteristics are as follows: splashing→face erosion→sheet erosion→crack→gulping, and no obvious sliding surface is seen.
The mechanical parameters of red clay slopes change during the wetting-drying cycles. The failure characteristics and mechanism of the red clay slopes are different from those of the general soil slopes. For the Guizhou red clay, the bath heater-artificial rainfall-simulated wetting-drying cycles are used to prepare a large-scale slope model. The moisture content,pore water pressure and temperature sensors are buried at different positions inside the slope. The evolution law and mechanism of the mechanical parameters of red clay slopes under circulation are analyzed. The results show that with the increase of depth,the soil moisture content of the slope is gradually weakened by the rainfall intensity, and the surface moisture content is obviously affected by the rainfall intensity. The moisture content during the drying period increases first and then decreases.Under the same rainfall intensity, the moisture content at the slope toe is the largest, followed by the slope surface, the slope shoulder, and finally the slope top. The surface pore water pressure increases during rainfall and osmosis, and decreases during drying. The greater the rainfall intensity, the greater the temperature change. As the depth increases, the temperature change of the slope gradually decreases. The temperature at the slope toe changes more than that at other parts. The failure characteristics are as follows: splashing→face erosion→sheet erosion→crack→gulping, and no obvious sliding surface is seen.
引文
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[4]朱泽勇,贺桂成,李丰雄,等.干湿交替条件下红土边坡破坏机理试验研究[J].长江科学院院报,2018,35(2):73-77.(ZHU Ze-yong,HE Gui-cheng,LI Feng-xiong,et al.Experimental study on failure mechanism of laterite slope under dry and wet cycles[J].Journal of Yangtze River Scientific Research Institute,2018,35(2):73-77.(in Chinese))
[2]陈南,吴立坚,周勇,等.红黏土边坡浅层破坏机理及稳定评价方法[J].公路交通科技,2016,33(3):37-42,88.(CHEN Nan,WU Li-jian,ZHOU Yong,et al.Failure mechanism of shallow layer of red clay slope and stability evaluation method[J].Journal of Highway and Transportation Research and Development,2016,33(3):37-42,88.(in Chinese))
[3]曾召田,吕海波,赵艳林,等.膨胀土干湿循环效应及其对边坡稳定性的影响[J].工程地质学报,2012,20(6):934-939.(ZENG Zhao-tian,LüHai-bo,ZHAO Yan-lin,et al.Wetting-drying effect of expansive soils and its influence on slope stability[J].Journal of Engineering Geology,2012,20(6):934-939.(in Chinese))
[4]朱泽勇,贺桂成,李丰雄,等.干湿交替条件下红土边坡破坏机理试验研究[J].长江科学院院报,2018,35(2):73-77.(ZHU Ze-yong,HE Gui-cheng,LI Feng-xiong,et al.Experimental study on failure mechanism of laterite slope under dry and wet cycles[J].Journal of Yangtze River Scientific Research Institute,2018,35(2):73-77.(in Chinese))