ISSN 1000-3665 CN 11-2202/P

    降雨强度对干湿循环作用下花岗岩残积土边坡破坏模式的影响

    Effect of rainfall intensity on failure mode of granite residual soil slope under dry-wet cycle

    • 摘要: 花岗岩残积土广泛分布于我国东南部,在降雨-干燥循环作用下,花岗岩残积土边坡易发生失稳破坏现象。为研究降雨强度对干湿循环作用下花岗岩残积土边坡的破坏模式及特征的影响,通过缩尺模型试验模拟了细雨和暴雨强度下边坡在历经3轮干湿交替作用下的响应,分别探讨了坡体变形、含水率以及基质吸力的变化特征。试验结果显示:当降雨强度为0.7 mm/min时,坡体基质吸力在15 min后趋近于0,边坡破坏时以浅层滑动模式为主,有明显滑动面;当降雨强度为1.6 mm/min时,雨水在坡面上形成径流,坡体基质吸力在15 min后趋近于0,边坡破坏时以表面冲蚀模式为主,无明显滑动面。结果表明:不同的降雨强度对花岗岩残积土边坡具有不同的破坏模式,干湿循环过程中干燥作用引起的雨水优势渗流通道,进而导致土体基质吸力的丧失,加速了花岗岩残积土边坡的失稳破坏。研究结果可为制定不同降雨强度下的花岗岩残积土边坡针对性防护措施提供参考。

       

      Abstract: Granite residual soil is widely distributed in the southeast of China, where slopes composed of this material are prone to instability and failure under alternating rainfall and drying conditions. To investigate the effect of rainfall intensity on the damage pattern and characteristics of granite residual soil slopes under the wet-dry cycle, this study employed scaled-down physical model tests simulating three cycles of wetting and drying under two distinct rainfall intensities. The experiments examined slope deformation, volumetric water content, and changes in matric suction. The results show that when the rainfall intensity is 0.7 mm/min, the matric suction tends to zero after 15 min, and the slope is mainly shallow sliding failure with obvious sliding surface. When the rainfall intensity is 1.6mm /min, the rainwater forms slope runoff, the matric suction tends to zero after 15 min, and the slope is mainly damaged by surface erosion without obvious sliding surface. Different rainfall intensity changes the failure mode of the granite residual soil slope, and the dry-wet cycle accelerates the instability failure of the granite residual soil slope. This acceleration is mainly reflected in the dominant seepage channels of rainwater caused by the drying effect, which in turn leads to the loss of the soil matrix suction. This study can provide basic information for the development of targeted protective measures for granite residual soil slopes under different rainfall intensities.

       

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