Identification and zonation of deep-seated toppling deformation in a metamorphic rock slope

摘要

Identifying deep-seated toppling failure presents unique challenges for the study of natural slope deformation in mountainous regions. In the absence of an effective quantitative approach, this study aims to provide a comprehensive grading system in order to establish a slope engineering geological model that can evaluate the deformation of a deep-seated metamorphic toppling slope. The toppling slope used in this study, located in Zhala, southwest China, affects a large area with a deformed rock mass of over 2.5 million m(3). In order to objectively reflect the intensity of rock mass toppling, the deformation phenomena of this deep-seated toppling slope are first described in detail. Then, a grading index system is proposed to evaluate the degree of toppling deformation. This comprehensive index system includes the dip angle change of the rock strata, tensile cracks, rock mass structure, weathering grade, and longitudinal wave velocity. The toppling slope is divided into four toppling intensity zones: a completely toppled zone, a highly toppled zone, a moderately toppled zone, and an un-toppled zone. The detailed description and subdivision of the degree of deep-seated toppling deformation is the basis of establishing a fine engineering geological model. Different from the previous when the bottom boundary of toppling was considered as the only potential control boundary, this paper reveals that there may be multiple potential control slip zones in the deep-seated toppling slope, and different deformation degree zones correspond to different stability. As an engineering slope, engineering treatment measures can be formulated according to the degree of toppling deformation.