ABSTRACT

In order to study the relation between the microscopic structure evolution and the macroscopic failure of the rock on the situation of the loading, according to the different character of the rock deformation, it considers the damage accumulation character and the fracture of the rock. Aiming atthefracture and the pore existing in the rockitself,it simulatesthe micro-cracks ofthe rock itself usingthe Weibull distribution ofthe rock material to produce the finite element program, introduces the concept of the damage degree, simulates the damage evolution degree of the rock inner in the process of loading. Based on the theory of rock tension damage, it gives the criterion of the rock tension damage, simulates the evolution process of the rock crack producing the finite element program. TakingtheBrazalianpanexperimentasexample,itsimulatestherock evolution process ofthe damage andthetensionfracture. The damage evolution process result shows that in the initial loading stage the rock particles squeeze and press, as the load increases gradually the microporeandcracksmake thestressconcentrate,the damage degree gradually increases and the ability to resist deformation decreases. After the load exceeds stress limit, the connectionof microcracklesdevelopsinto macrobreakingplane,thusenteringdestabilizing breakage stage. The tension fracture result shows that because the rock tensile strength is low the fracturewillformdiscontinuoussurface;thestressdistributionchangesaroundrockcrackle, partial stress is released, new stress concentration is formed and stress is transferred. Through the analysis, it can provide the theoretical basis for studying the crack extending and evolution law of the rock and forecasting and predicting the instability failure of the rock system.

1 INTRODUCTION

Rock is a heterogeneity material and has the defects of micro cracksandholesininnerstructure. In a great extent therockheterogeneitydeterminesthecomplexity and discreteness of itself mechanics characteristic. In the process ofthematerialloading,becauseoftheinner damage graduallyincreasing,itleadsthematerial instability damaged; the rock material is also this. Before and after the forming process of the rock itself, it endures the differentgeologyfunction,soitisvaluablethat studies thedamageanddeformationevolutioninrock whole loadingprocess. The process researches of the material damage and fractureis hotspot and difficulty of mechanics field. The solid material's damage for exampletherockisacumulativedamageprocess,isa cumulative processofthemicrostructurechangein physics andisacumulativeprocessofproducingand extending of the macro defects in mechanics.

The damage process simulation is the hotspot of solid mechanicsresearch, especiallythenon-continuum damage simulation exists many problems. At present, the finite elementmethodwidelyusedisbasedon the continuum assumption.

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