水位骤降对边坡稳定性影响的模型试验研究

 自然界中存在着大量的临水边坡，比如河岸、海堤、土石坝、水库库岸以及湖岸等，边坡外水位的骤降极易诱发此类临水边坡的滑坡。通过大型模型试验研究水位骤降引致临水边坡滑坡的原因及失稳模式。模型边坡的尺寸为15 m×5 m×6 m(长×宽×高)，边坡部分的高度为4 m。在试验中，通过水位控制系统实现坡外水位的骤降，利用数码摄像、高精度传感器、侧面示踪点等仪器设备详细记录水位骤降过程中边坡内的孔隙水压力、土水总压力，滑动面形态及坡面裂缝的形成和发展过程，揭示水位骤降引致边坡失稳的原因及失稳模式。试验结果表明，坡外水位骤降时，坡内水位的下降速度显著滞后于坡外，产生指向坡外的渗流，是滑坡产生的重要原因；松散填土边坡的失稳模式为有多重滑面的牵引破坏模式。该研究结果有助于深入认识水位骤降引致滑坡的机制，可为治理此类滑坡提供科学依据。

MODEL TEST STUDY OF SLOPE INSTABILITY INDUCED BY RAPID DRAWDOWN OF WATER LEVEL

There are many slopes adjacent to water in nature，such as river banks，coastal dykes，earth dams，and reservoir and lake banks. Rapid drawdown of water levels often induces landslides of this kinds of slopes. A large-scale model test was performed to investigate the failure mode and causes of landsides of the slope adjacent to water during rapid drawdown of water level. The model slope is 15 m long，6 m high and 5 m wide，and the height of sloping part is 4 m. A water-level control system was developed to implement the simulation of the rapid drawdown of water level. Pore water pressures，total earth pressures，the slip surfaces and formation and development process of cracks on the slope were recorded during the simulation process by digital camera，high precision sensors，side tracers，etc.. The model test results indicate that the pore water pressure inside the slope showed a significant delay related to the drawdown of water level outside the slope. It indicates that measures that can lower the water levels inside the slope should be helpful to stabilize the slope. The failure mode that developed during rapid drawdown of water level was of the multiple retrogressive type. The experimental results can provide an improved understanding of the physical behavior and failure mode of soil slopes subjected to rapid drawdown of water level.