Application of DICM on Similar Material Simulation Experiment for Rock-Like Materials

Abstract

e digital image correlation method (DICM) has been applied to similar material simulation experiments for rock-like materials, to overcome the weakness of traditional measurements, for example, data discontinuous. In this paper, the movement and fracturing process of the overlying strata during excavation are observed and studied, and the distributions of stress, strain, and deformation in the overlying strata are obtained based on similar material simulation. e DICM is applied to improve the testing method and to optimize the discontinuity of testing points; of course, the difference of rock deformation in the overlying strata during excavation is considered. Full-field deformation and strain are analyzed by the DICM. To verify the accuracy of the DICM, results obtained from the DICM, numerical simulation and similar material simulation, are compared. e DICM can reflect the characteristics of locality and randomness of rock-like materials more real than numerical simulation, and comparing with similar material simulation, it can directly reproduce the movement and fracturing process of the overlying strata during full-field excavation. It shows that, the DICM is entirely feasible to using in the large scale full-field deformation measurement on complex rock structure, and it is of theoretical importance for testing for rock-like materials.

Similar Material Simulation Study on Protection Effect of Steeply Inclined Upper Protective Layer Mining with Varying Interlayer Distances

“…e similar material simulation experiment is a reduced-scale approach according to similarity criteria [24][25][26]. e selected similar Advances in Civil Engineering materials must have very similar physicomechanical properties of engineering prototype (referred as coal-rock strata here).…”

“…At present, similarity criteria are based on elastic theory and dimensional analysis method. According to the pressure-relief mechanism of protective layer mining, the following similarity criteria should be satis ed in similar material simulation experiment [22][23][24]:…”

“…e type and proportion parameters of similar material determine whether experimental results obtained can represent mechanical responses of prototype. Similar material simulation experiments have been widely employed, but how to obtain accurate and optimum proportioning parameters is urgently needed to be investigated in coal mining [20][21][22][23][24][25][26]. In this section, the river sand, cement (containing gypsum and y ash), and water are used and mixed to manufacture a new similar material, which is used to represent various coal-rock strata around the protective layer in the coal mine.…”

“…e coal-rock strata of on-site engineering are simulated by similar materials including sand, cement (containing gypsum and fly ash), and water mixtures. To ensure proportioning ratios and mechanical parameters for each stratum are satisfied, similar material for each stratum or layer is manufactured using a method of layered filling and compaction [24], in which a moderate amount of mica powder is sprinkled between different layers as laminated weak surfaces. e physical similarity simulation bench should be firstly rotated an angle of 45°to perform the filling of similar materials.…”

“…In short, protection effect of steeply inclined upper protective layer mining with varying interlayer distances is not fully understood and needs further investigation. Compared to site observation and numerical simulation, similar material simulation [20][21][22][23][24] in a laboratory can simulate real physical object (i.e., engineering prototype), with similar materials having mechanical properties similar to those of a prototype according to certain similarity criteria. As the similar material model has all or most of the major characteristics of the prototype, it can reflect failure or deformation process of prototype truly and visually.…”