基于离心试验的边坡倾倒变形下弯折带演化特征

边坡倾倒变形过程中岩层弯折带的发育特征与演化规律是研究该类边坡变形破坏的地质过程与力学行为的关键. 为了揭示坡角变化对弯折带发育规律的影响，以澜沧江古水水电站坝前倾倒变形体为原型边坡，概化设计3组不同坡角的试验模型，通过离心模拟试验，尝试再现反倾层状岩质边坡倾倒变形的演化过程，分析边坡内部岩层弯折带的发育特征. 研究结果表明:边坡倾倒变形主要发生在倾倒折断基准面上方，基准面与层面法线的夹角位于12°～16°，该值不随坡角的改变而发生变化；边坡倾倒变形时，弯折带由坡脚开始以参差阶坎状的形式向坡顶延伸直至贯通，坡度陡的边坡会在一级弯折带上方的已倾倒岩体中产生新的次级弯折带，边坡倾倒折断模式由单级折断逐渐转为多级折断；弯折带孕育过程可概化为3个阶段:岩层弯曲变形、坡脚破裂-弯折带向坡顶延伸、弯折带贯通-坡体临界失稳；坡角变化对边坡倾倒变形发育特征有较大影响，随着坡角的增加，边坡倾倒变形范围扩大，程度加剧. 

Slope Toppling Deformation and Development Characteristics of Bending Belts by Centrifugal Model Test

Development characteristics and evolution law of the rock bending belts during the slope toppling deformation process is the key tostudying the geological development and mechanical behaviour of counter-tilt layered rock slopes in the process of deformation and failure. In order to reveal the influence of the slope angle change on the development law of the bending belts, the toppling deformation body in front of the dam of Gushui Hydropower Station of Lancang River is used as a prototype to generalize three sets of slope centrifugal test models with different slope angles. The centrifugal simulation tests were conducted in an effort to reproduce the evolution process of the toppling deformation of the counter-tilt layered rock slope and analyze the development characteristics of the rock bending belts inside the slope. The results indicate that the slope toppling deformation mainly occurs above the dumping and breaking datum plane, the angle between the datum plane and the normal of the rock bedding planes lies between 12° and 16°, and the value does not change with slope angle. In the process of slope deformation, the bending belts extends from the foot of the slope to the top of the slope in a stepped manner until it penetrates. A new secondary bending belts in the dumped rock mass generate above the primary bending belts in steep slope, and the slope failure mode gradually changes from single-level break to multi-level breaks. The evolution process of the bending belts can be generalized into three stages: rock layer toppling deformation, slope foot rupture-bending belts extending to the slope top, bending belts penetration to critical instability of slope. The slope anglechange has great influence on the development characteristics of slope toppling deformation. As the slope angle increases, slope toppling deformation expands and aggravates.