黄土高填方边坡渗透变形机理的物理模拟

天水市是我国黄土滑坡分布最密集、灾害最严重的地区之一。大面积的挖填方会改变场区的地下水渗流场,从而影响高填方边坡的稳定性。本文以天水地区马兰黄土为研究对象,通过野外详勘与室内物理模拟试验,对马兰黄土高填方边坡的渗透变形机理进行研究。结果表明:受填方前原始地形的影响,凹陷地形易于汇水,地下水流动受阻,易形成积水区,使地下水位抬升高度较大。随着时间的累积,地下水不断浸泡地基土,使其强度劣化,加之毛细水上升作用使地基发生湿馅和湿化沉降,易在边坡坡脚等富水区产生蠕滑变形,并牵引边坡后缘发生滑移拉裂,发生渐进式破坏而引发较大规模的边坡滑移。通过物理模拟,得出该地区马兰黄土高填方边坡受地下水影响产生的变形滑移模式为“渐进后退—牵引式滑移”。

Physical Simulation of Seepage Deformation Mechanism of Loess High Fill Slope

Tianshui City is one of the areas with the densest distribution of loess landslides and the worst disasters in China. Excavation and filling of a large area will change the groundwater seepage field in the site area, thereby affecting the stability of the high-fill slope. This paper takes Malan loess in Tianshui area as the research object. Through detailed field survey and indoor physical simulation test, the seepage deformation mechanism of Malan loess high-fill slope is studied. The results show that: affected by the original topography before filling, the recessed topography is easy to catch water, the flow of groundwater is blocked, and it is easy to form a stagnant area, which makes the groundwater level rise higher. As time accumulates, groundwater continuously soaks the foundation soil, deteriorating its strength, and the rise of capillary water causes the foundation to undergo wet filling and wet settlement, which is prone to creep deformation in the water-rich areas such as the foot of the slope and drag the side. Sliding and tearing occurred on the trailing edge of the slope, and progressive failure occurred, which caused a large-scale slope slippage. Through physical simulation, it is concluded that the deformation and slip mode of the Malan loess high fill slope in the area affected by the groundwater is "gradual retreat-traction slip".