Research And Application Of Micro-deformation And Failure Characteristics Of Reef Limestone Based On Particle Flow Discrete Element

Reef-limestone has special composition and structure,which determines its susceptibility to dissolution and leads to porosity increase.This paper summarizes the predecessors about reef limestone mineral composition,microstructure and property characteristics of the research results,obtained the physical parameters and the understanding of the mechanics has a strong correlation,and on this basis,through the random clustering algorithm to construct different porosity reef limestone discrete element model,simulation of different porosity reef limestone in various numerical experiments under the condition of mechanical strength characteristics change and microstructure deformation and destruction.The correlation between macroscopic mechanical parameters and porosity was calculated.The differences of deformation and failure and fracture development of reef limestone under different porosity are analyzed.Finally yongle longdong velocity inversion with three sand geological model established on the basis of three yongle longdong reef limestone sand body piercing numerical model,the shape of the lower body piercing power load dynamic response analysis,the main research body piercing displacement under dynamic load,the speed of response characteristics,such as changing law,and discusses the damage mechanism of body piercing under dynamic load.The results showed that:(1)The discrete element model of reef limestone with different porosity built based on random clustering algorithm can well simulate the pore structure of reef limestone.Using the model.(2)With the increase of porosity,all kinds of macroscopic mechanical properties decrease in different ways.The friction Angle and cohesion also decrease in a certain trend.When the porosity is low,the whole structure of the specimen is intact,and the cracks grow uniformly during the crack development.High porosity "skeletonization" effect significantly,due to the interaction between pore micro fissure development mode change,lead to originated in the fracture around the mutual penetration and mutual penetration,eventually make sample macro failure happens,and damage showed the characteristics of low intensity,low strain,the main damage type of structural damage.(3)The existence of the Sansha Yongle Cave will block the transmission of vibration waves;Due to the mechanical properties of reef limestone,the main failure type of the cave wall is tensile failure.When the incident wave reaches the cave wall,it causes tensile stress near the adjacent free boundary and produces vertical tensile cracks at the cave wall.Meanwhile,these vertical cracks gradually connect to form a nearly parallel vertical crack group,which is a typical spallation reaction.(4)The degree of deformation and damage of the cave wall expands with the increase of the dynamic load amplitude.The greater the peak strength of the dynamic load,the more cracks are produced.Finally,the micro cracks penetrate to form fragments of the slope,causing part of the cave wall to separate from the main body,causing local Instability and collapse;the porosity of the reef limestone on the upper part of the cave wall is higher than that of the lower part,so the upper cave body is more likely to form slope fragments than the lower part of the cave wall.When strong external dynamics are carried out,the upper part of the cave wall is more likely to fail and collapse.The results of this research can enrich the mechanical system of reef limestone,provide theoretical references for the research on the deformation and failure characteristics of reef limestone,and provide suggestions for the construction of island and reef projects,tourism development,and landscape protection.