基于坡角变化的反倾层状岩质斜坡倾倒变形离心模型试验研究

Centrifugal model tests on toppling deformation of counter-tilt layered rock slopes based on change of slope angle

基于临空条件变化对倾倒变形斜坡影响的认识,以澜沧江古水水电站倾倒变形边坡为原型,通过3组斜坡模型的离心试验,模拟不同坡角条件下反倾层状斜坡的变形演化与破坏过程,获得坡角变化与倾倒变形发展演化之间的关系。研究结果表明:反倾斜坡倾倒破坏最先发生在坡脚位置,而后向上部发展。坡角越陡,产生这种变形需要的累积时间越短;反倾层状岩质斜坡倾倒变形演化过程可分为4个阶段:(1)斜坡岩体倾倒,斜坡后缘沉降;(2)坡脚岩层破裂,岩体"倾倒–弯曲"变形;(3)折断带从坡脚向坡顶延伸,坡顶岩体张拉破坏;(4)折断带延伸直至贯通,岩体"倾倒–折断"破坏;其它条件不变的情况下,坡度较陡的斜坡发生倾倒变形的范围更大,更可能在倾倒过程中产生多级折断带,造成斜坡破坏的能量释放不是一次性的;坡角的变化会导致斜坡最终失稳模式的差异,坡角越缓,倾倒变形斜坡更有可能演化成为整体滑移失稳,坡角越陡,岩体倾倒后出现崩塌的可能性更大。

Based on the understanding of the effects of changes in the critical conditions on toppling deformation slopes, taking the toppling deformation slope of Gushui hydropower station of the Lancang River as the prototype, and by simulating the deformation evolution and failure process of counter-tilt layered slopes under different slope angles through centrifugal tests on three sets of slope models with different slope angles, the relationship between the change of the slope angle and the development of the toppling deformation is obtained. The results indicate that the toppling damage of the counter-tilt slope occurs first at the foot of the slope and then develops upward. The larger angle will shorten the cumulative time required for deformation. The evolution process of the toppling deformation of the counter-tilt layered rock slope can be divided into 4 stages:(1) The rock body of the slope falls, and its trailing edge settles.(2) The rock at the bottom of the slope is broken, and the "toppling and bending" deformation occurs.(3) The broken zone extends from the bottom to the top of the slope,and the rock at the top of the slope is damaged by tension.(4) The broken zone extends until it is coalescent, and the "toppling and breaking" deformation occurs. If other conditions remain unchanged, the steeper slopes have a greater range of toppling deformation and are more likely to produce multi-stage broken zones during dumping, and the energy that causes the slope damage is released multiple times. Changing the angle of the slope can lead to differences in the final destabilization pattern. The smaller the slope angle, the more likely the deformed slope of the dump will evolve into an overall slip instability, and the steep slopes are more likely to collapse after toppling.