滑坡不同变形阶段演化规律与变形速率预警判据研究

Critical deformation velocity of landslides in different deformation phases

预测预警是国际滑坡灾害研究的热点与难点,目前滑坡不同变形阶段历时与变形速率临界值方面的研究存在不足。为深入探索滑坡不同变形阶段演化规律与变形速率预警判据,将滑坡变形演化过程划分为初始变形、匀速变形、加速变形和急剧变形4个阶段,基于滑坡数据库信息,采用统计分析方法研究滑坡不同变形阶段历时特征及其与不同影响因素的相关性、总结不同变形阶段裂缝发展及宏观特征、分析不同变形阶段滑坡位移速率预警判据。通过研究发现：（1）滑坡加速变形阶段历时18～1 080 d,接近一半的滑坡加速阶段历时位于区间30～90 d;绝大部分滑坡急剧变形阶段历时小于30 d。（2）滑坡破坏模式、滑体方量、滑面类型与滑坡变形阶段历时相关,其中滑面类型与变形阶段历时的关系最为密切,滑面为硬性结构时滑坡加速与急剧变形阶段历时较短,滑面为软弱层面时加速与急剧变形阶段历时较长。（3）滑坡进入加速变形阶段时裂缝最大宽度为1～50 cm,进入急剧变形阶段时最大裂缝宽度为4～126 cm,其中土质滑坡与堆积体滑坡临界裂缝宽度较大,岩质滑坡临界裂缝宽度相对较小。（4）滑坡进入急剧变形阶段位移临界速率一般不超过50 mm/d,倾倒型滑坡速率临界值相对较大,软弱滑动面滑坡该位移速率临界值较硬性滑动面滑坡大。（5）各种滑坡进入加速变形阶段的位移速率均不大,此速率值与破坏模式关系密切。破坏模式为滑动破坏的滑坡该位移速率阈值基本都不超过4 mm/d,倾倒破坏或崩塌破坏的滑坡该阈值稍大,一般大于4 mm/d。

Prediction and early warning is one of the difficult issues of landslide. Currently,no enough attention was paid to the elapsed time and the critical deformation velocity of landslides in different deformation phases. In order to further explore the warning criterion of deformation velocity of landslides,the process of landslide was divided into four phases including an initial deformation phase,a uniform deformation phase,and an accelerated deformation phase and a sharp deformation phase. The landslide database was studied with the statistical method. The accelerated deformation phase lasted from 18 days to 1 080 days,and the elapsed time of nearly half of the landslides was within 30 days to 90 days. The sharp deformation phase of majority landslides lasted less than 30 days. The elapsed time of landslides in different deformation phases related to the failure mode,the landslide volume and the sliding surface type. The elapsed time and the sliding surface type are most closely related. When the slip surface is a rigid structure,the acceleration and sharp deformation phases are shorter. When the slip surface is a weak bedding surface,the acceleration and sharp deformation phases are longer. In the acceleration deformation phase,the maximum width of crack is 1–50 cm. In the sharp deformation phase,the maximum width of crack is 4–126 cm. The cracks of soil landslide and talus slide are wider,and the crack of rock landslide is relatively narrow. The critical deformation velocity of landslide entering into the sharp deformation phase is not more than 50 mm/d. The threshold of toppling landslide is relatively large,and the threshold of landslide with the weak sliding surface is larger than the landslide with rigid sliding surface. The critical deformation velocities of various landslides entering into the acceleration deformation phase are not large which are closely related to the failure mode. The threshold of sliding landslide is basically no more than 4 mm/d,and the threshold of toppling landslide or collapse landslide is slightly larger,generally larger than 4 mm/d.