1、英文原文 Physical simulation of rock burst induced by stress waves LU Ai-hong, MAO Xian-biao, LIU Hai-shun School of Sciences, China University of Mining & Technology, Xuzhou, Jiangsu 221008, ChinaAbstract: The behavior of stress wave propagation in rock walls and the process of rock bursts were simulat
2、ed by application testsof material similar to rock. Results show that 1) the attenuation characteristics of stress waves were related to the material properties,stress waves attenuate more quickly in soft material and 2) when the explosion load was applied at the top of the roadway, thenumber and th
3、e length of the cracks increased with a decrease in the distance between the explosive point and roof of the roadway.When the distance was 280 mm, only some chips appeared near the source, when the distance was 210 mm, some small cracks started to appear near the road-rib and when the distance was r
4、educed to 140 mm, larger cracks appeared at the road-rib. It can be concluded that, under a given stress the number of cracks is closely related to the intensity of stress waves. The cracks in the surrounding rock can be reduced by controlling the intensity of the stress waves and rock bursts can be
5、 avoided to some extent by preventing the formation of layered crack structures. A new experimental approach has been provided for studying rock bursts by using physical simulation.Key words: similar material; stress wave; physical simulation; rock burst1 Introduction With the increase in mining dep
6、th, the frequency and intensity of rock bursts increase continually, seriously threatening the safety in coal mine production. Controlling the mechanism of rock bursts has attracted much attention of scientists who have proposed a series of theories on the mechanism of the origin of rock bursts and
7、some countermeasures for preventing them from taking place. Classic theories includes: intensity theory, energy theory, impact tendency theory, three guideline theory and others15. However, there is not one accepted theory about the mechanism of rock burst formation because it has a rather complex d
8、ynamic instability. It is therefore urgent to study the mechanism of the formation of dynamic hazards such as rock bursts. It is well known that the main reason for rock bursts lies in the deformation energy in hard rocks and the mechanical processes involved in rock bursts are generally regarded as
9、 static (or quasi-static)49. However, static load theory cannot explain all the mechanisms about rock bursts. The accumulation of strain energy is a necessary condition for rock bursts but not a necessary and sufficient condition. Therefore,an external disturbance is necessary for a rock burst. More
10、over, stress waves may be produced by driving, blasting, roof breaking, weighting of the working face, and seismic waves in mining processes,i.e., external disturbances are often introduced before the occurrence of a rock burst. It is necessary to study the effect of stress waves in rock burst. Mean
11、while,simulation is an important means in the study of rock bursts because it can simulate the rock burst process and provide some important information about the mechanism of its incidence, failure spots and themethods of failure. Liu studied the effect of rock failure caused by a superimposed sine
12、 wave, concluding that the disturbance of stress wave decreases the strength of rocks10. The relationship between the disturbance and rock burst needs to be further investigated. Xi simulated the effect of static load on the propagation of known cracks and their unstable failure by using a precrack
13、in the rock and thus obtaining the distribution of its speed of propagation11. However, the propagation of cracks under a dynamic load has not been investigated. In our investigation, the incidence and development of rock bursts were simulated with material similar to rock and the mechanismof splitt
14、ing typerock bursts was studied.2 Similar material and simulation experiment2.1 Similar material In geotechnical engineering,selectionand experiments with similar material arerelatively mature forstatic problems with elasticstages.However,few investigations have been carried out on the characteristi
15、cs of this material beyond the elastic stage, especially those of dynamic unstable failures. In our experiment, sand, gypsum, calcium carbonate,cement, borax and water were used to prepare material similar to rocks according to the proportions listed in Table 1 and the mechanical properties of this
16、material were determined. For the measurement of mechanical properties, standard specimens with =50mm in diameter and l=100mm in height were prepared, followed by drying and then tested by using the MTS Electro-hydraulic Servo test system. Table 1 Parameters and mechanical properties of similar materialNumberSandGypsum Calcium carbonate Water Borax c (MPa) E (GPa)122.53.62.
