Study On The Engineering Characteristics Of Rock And Soil Material Based On Numerical Test

The particle flow is selected to do the numerical test. The particle assembly meeting the specified probability distribution is built by program compiled by embedded language of fish. Then, the virtual implementation of rock mechanics experiment is done based on these. Six problems, such as the macro-response of rock and soil material's micro-parameters, inner scale ratio, size effect, effect of loading rate, engineering characteristics of material affected by particle size and the rupture process of rock with its fractal feature are studied by the specialized numerical virtual test. The main conclusion is drawn as follows.1. A simple mechanics relation between particles can result in a complex response. The relation of micro-parameter and macro-parameter is not a simple summation, which is the dialectical relationship of overall with some. The mechanics behavior of the assembly is the enhancement and enlargement of the particles'mechanics behavior. The effects of friction coefficient, contact radius multiplier and elastic modulus are comprehensive. The increasing of elastic modulus can cause the decreasing of strain, additional fracture, sharp reduction in energy and the irregular vibration of strength. The increase of contact radius multiplier results in the enhancement of material strength and deformation features, increase of rupture number and energy. So is the law of friction coefficient. However, the effect of micro-strength is independent, whose increase only affects the macro-strength.2. The twelve kinds of computing schemes of uniaxial compression numerical test are designed to analyze the inner ratio of rock and soil material being the maximum of particle diameter divided by the diameter of sample. If the ratio is large than the inherent ratio of material, the engineering features of material appear big vibration. Conversely, the experimental results are stable. It is found that the sandstone's scale ratio is 0.01 which illustrates the existence of the scale ration in particle assembly material.3. The numerical test with different height-to-diameter ratio and confining pressure is comprehensively analyzed by means of rupture process, spatial location and number of fracture system, curve of stress and strain, energy evolution methods. It is found that the optimum ratio is 2.5-3.0, obtaining by curve of stress and strain, peak strength, secant modulus and rupture shape of numerical sample methods, that the optimal height-to-diameter ratio drawn by energy method is 3.0, and that the latter method is more stable than the former. End friction effect is apparent under condition of lower confining pressure and height-to-diameter ratio. If the ratio being large than 2.5 and confining pressure large than 10MPa, the end effect is weakened. When the ratio is small value, the material presents the pseudo-high-strength. Conversely, the rock appears false-high-brittle. 4. The priority developing shear zone don't any longer exist during the rupture process of material because of the increase of loading rate, which makes the shear zone expands with the similar velocity, resulting in cone shape of rupture surface. It is found that the peak strength and deformation parameters of rock are enhanced with the developing of loading rate. The damage and rupture mechanism of material lies in which the cohesion energy is firstly cumulative, then cohesion strength is overcome, the little fracture is produced, the fracture is driven by cumulative elastic strain energy, finally the apparent rupture surface through the sample, when the local weak zone leads the post-peak phase of material's deformation and instability process. The own strength of material don't determine the damage process.5. The computing schemes with different clump radius, number and spatial location or with the same spatial location and number of clumps are designed to study the mechanics behavior of clump structure. It is found that the material features are improved with the increase of clump number and radius. The damage mechanism of material with different dimension clumps lies in which the clump radius increasing can results in the decrease of matrix quantity within the material, rupture is easily produced in matrix, so the number of fracture is lessened and the action of cohesion energy is lowered, conversely the action of the strain energy is enlarged. The clump with high strength isn't easily damaged, its action is delivering force to matrix. Therefore, damage often happens around the clump. Because the density of clump in vertical direction is large than the horizontal, and the horizontal confining is limit, the rupture often vertically expands and horizontally opens, looking like Yan arrange. 6. The rupture process of numerical samples with different dimension is tracing, describing and studying by means of virtual implementation method and image disposal. It is found that there exists statistical self-similarity in rock rupture system, that the applicability of box-counting-method used to calculate fractal dimension is better than sandbox method, whose computing result often vibrates with the different height-to-diameter of sample, that the fractal dimension is decreasing with the confining pressure and increasing with the loading process, because the loading changes the initial uneven degree of random defects within rock, which limits the deterioration of material features within local zone and worsens the complexity of fractures.