基于弹性波波速的降雨型滑坡预警系统

Early warning of rainfall-induced landslides based on elastic wave velocity

降雨是诱发滑坡最主要的因素。为减少滑坡灾害造成的人员伤亡和经济损失,滑坡早期预警系统成为了最佳选择之一。根据弹性波传播的基本原理和基于降雨型滑坡变形破坏的特点,提出利用弹性波波速来反映边坡表面土体含水率和位移的变化。开发研制了一套三轴渗流-弹性波测试三轴仪和相关系统。该装置能让水从底部渗入土体,模拟降雨入渗土体的过程,同时能测试弹性波波速。试验过程中同步测试含水率、变形和弹性波波速的变化。还进行了降雨滑坡模型试验。利用三轴弯曲元注水试验和降雨滑坡模型试验,深入分析和研究降雨引起的土体滑坡过程与弹性波波速演化规律,揭示波速与含水率和变形的耦合关系。研究结果表明,弹性波波速随着含水率的增大而缓慢减小,随着变形的增大而急剧减小,临近失稳时,波速骤然减小。根据试验结果对含水率和变形导致弹性波波速减小可能的机制进行了解释,提出弹性波在波速骤然减小时发出滑坡预警。研究结果为滑坡防灾减灾和预测预报提供新的方法和可靠的依据。

Rainfall is the most important factor in triggering the landslide. To reduce the loss of life and property caused by the landslide disaster, the early warning system against landslides becomes one of the best choices. Based on the principle of elastic wave propagation and the characteristics of deformation and failure of rainfall-induced landslides, this paper proposes to use the elastic wave velocity to detect the changes in soil moisture content and displacement on slope surface. The bender elements and ceramic disk, incorporated in a triaxial apparatus, are used to measure the S-wave and P-wave velocities in soils subjected to water infiltration. The device allows water to infiltrate into the soil from the pedestal to simulate the process of rainfall infiltration into the soil. The moisture content, deformation and elastic wave velocity are simultaneously measured during the tests. Besides, the rainfall model tests are carried out. Based on the triaxial model tests, this study reveals the process of rainfall-induced landslides, the evolution of elastic wave velocity, and the coupling relationship among the wave velocity, water content and deformation. The results show that the elastic wave velocity decreases slowly with the increase of water content, but decreases sharply with the increase of deformation, indicating the initiation of the instability. We also interpret possible mechanisms of the reduction of elastic wave velocity caused by water content and deformation. This paper provides a new method and reliable basis for an early warning system for rainfall-induced landslides and slope failures.