Relationship between the Surface Cracks and the Internal Fractures of A Slope Based on Fracture Degree

The relationship between the surface cracks and the internal fractures of a Slope based on fracture degree is proposed. Fracture degree of a slope is defined as the ratio of the current crack number to the catastrophic crack number. The relationship between surface crack and internal fracture state is established with numerical simulations on a series of typical slopes. The study shows that there exists an obvious complementary effect between fracture degree of the surface and fracture degree of the slip surface, which can help to find the critical state of a slope through crack on the earth surface. Introduction For landslide analysis, there have been lots of methods, among which the most widely used include limit equilibrium method[1,2], strength reduction method[3,4], and etc. The limit equilibrium method is an effective way to analysis the stability of a slope and has been successfully used in many practical engineering problems. The core concept of this method is to divide the whole slope body into a series of straight rigid blocks, and determine the safety factor according to force equilibrium on the slip surface. Strength reduction method has considered the deformation and stress-strain relationship of the slope with finite element method(FEM). Slope with complex landform and geological conditions can also be calculated. Since fracture is an essential feature in the evolution process during landslide disasters, stability analysis method considering fracture gets more and more attention. With the development of computer science, numerical simulation becomes a powerful tool in slope stability analysis. Discrete element method proposed by Cundull[5] could describe the discontinuous behavior of the joint body, which is widely used in rock mechanics and slope engineering[6,7]. Discontinuous deformation analysis(DDA) introduced by Shi[8] is another effective method to investigate the fracture of a slope, and numerical expression of this method is more rigorous. Li[9,10] introduced a numerical method called continuum-discontinuum element method(CDEM), which coupled FEM and DEM. With this method, the continuous body is calculated with FEM and the boundary of block is calculated with DEM. CDEM is suitable to describe the growth of cracks and simulate the progressive failure process of the landslide. The evolution of cracks on the earth surface can usually be observed during different stages of a landslide. Surface cracks could be a clear message that would reveal the current state of a slope. The number of surface cracks should reflect the damage degree of a geologic body and the state of internal force during failure process. The information obtained from surface cracks contains displacement field of the earth surface, which is more informative comparing to the monitoring points. Surface cracks will influence the effect of rainfall, since cracks could help water permeate into the geologic body. Meanwhile, surface cracks can be obtained through very simple measurements without using professional monitoring devices nor setting up complex monitoring network. So it is quite necessary to establish the relationship between surface cracks and internal facture state. The objective of this paper is to investigate the relationship between the surface cracks and the internal fractures based on fracture degree and CDEM simulation. Fundamental concept and International Conference on Modeling, Analysis, Simulation Technologies and Applications (MASTA 2019) Copyright © 2019, the Authors. Published by Atlantis Press. This is an open access article under the CC BY-NC license (http://creativecommons.org/licenses/by-nc/4.0/). Advances in Intelligent Systems Research, volume 168