A method for simulating the catastrophic evolution of overlying karst collapse based on discrete element method is presented

Abstract

The invention belongs to the research field of geological disaster mechanism, and discloses a method for simulating the catastrophic evolution of overlying karst collapse based on the discrete elementmethod. The mechanism of overlying karst collapse and the catastrophic evolution process are analyzed by using the discrete element method. The whole process of karst collapse is revealed from the microscopic angle, including: crack formation, particle spalling, soil cavity formation, soil cavity expansion, overburden collapse and so on. The displacement of overburden soil particles, the development trend of cracks and the variation of system unbalance force are analyzed in order to truly reflect the multi-field variation characteristics of the catastrophic main body (overburden soil) under the action of external forces. The invention obtains the critical soil hole equilibrium height and the critical groundwater flow velocity formed by the soil hole of the overlying karst collapse by using the discrete element numerical simulation method, and compares with the theoretical result, and the simulation result can provide a reliable basis for the exploration and treatment of the karst collapse geological disaster, the disaster prevention and mitigation work.

Description

technical field [0001] The invention belongs to the field of geological disaster mechanism research, in particular to a method for simulating catastrophe evolution of covered karst collapse based on a discrete element method. Background technique [0002] At present, the existing technologies commonly used in the industry are as follows: [0003] Covering karst collapse disasters are very difficult to prevent and control karst collapse disasters because of their concealment, suddenness, uncertainty, and complex mechanism. In order to reduce the occurrence of karst collapse disasters, it is necessary to analyze the covering karst collapse. [0004] The numerical simulation methods of karst collapse mainly include finite element method, finite difference method, integral equation method and boundary element method. The most widely used method is the finite difference method - FLAC3D. FLAC3D is a numerical simulation method based on the theory of continuum mechanics. It ofte...

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Problems solved by technology

Based on the theory of "continuum mechanics", this type of method can only simulate the mechanical behavior of the overburden soil (soil cave) in overburden karst areas such as large deformation, deflection, and plastic flow; Composed of broken solid particles, the macroscopic deformation of soil is not mainly due to the deformation of the particles themselves, but due to the change of the position between particles, that is, the arrangement. The above traditional numerical simulation methods cannot reflect the dynamic migration, latent erosion and collapse of soil particles. solution process

[0007] In the prior art, the micromechanical program PFC (Particle Flow Code) for the cracking and crack development of granular aggregates and the flow of particles (large displacement) has not yet established a numerical model of overlying karst collapse, which cannot be simulated. Expansion of soil caves, exfoliation of particles, and subsidence of the ground surface lead to the inability to analyze the displacement of soil particles and the expansion of cracks in the process of karst collapse from a microscopic point of view; it is impossible to quantitatively reveal the influencing factors of overburden karst collapse ( Geological conditions, external forces), to solve the critical threshold value of the initial soil cave formation and surface subsidence, and did not conduct a comparative analysis with the theoretical value, which cannot provide a theoretical basis for the management of karst subsidence disasters

[0008] During the failure process of the soil cave in the overburden karst system, there are not only large deformation mechanical behaviors based on the continuum assumption, such as deflection and plastic flow, but also subsurface erosion, migration, and caving of soil particles on the surface of the soil cave. The mechanical behavior of the discontinuous medium hypothesis, but the traditional numerical simulation method based on the "continuum mechanics theory" cannot describe these mechanical behaviors

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