Rock bursts

Coal miners also risk being exposed to other deadly gases, including carbon monoxide, a poisonous by-product of partially burned coal. Carbon monoxide is deadly in quantities as little as 1%. It is especially prevalent in underground mines after a methane explosion. In the early 1800s, after a gas explosion, coal miners used canaries to test for carbon monoxide. If the canary died, the miners increased ventilation in the mine to remove the carbon monoxide. The miners then conducted the same test with another canary and repeated the process until a bird survived. Miners also tested for carbon monoxide and methane with a small flame. If the flame s size increased, methane was present in the air if the flame went out, carbon monoxide was present. 

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With the rapid development of the national economy and the increased mining depth coal and rock dynamic disaster is increasing ay by day. In order to ensure life safety, safe, reasonable and efficient mining method are very necessary. Then the research on dynamic mechanical properties of underground rock is also very importanti l Almost all of the dynamic disaster, such as broken rock, rock burst, coal and gas outburst and other dynamic disasters had certain correlation with the rock failure under impact load and stress wave s propagation in the rocU f Because research on the dynamic mechanical properties of rock is minimal in our country, many law needs to refer to foreign datal - l, which leads to the lack of theoretical basis in China. Rock burst and other dynamic disaster tend to occur in coal seam with limestone roof Therefore, in order to effectively control the mine dynamic disasters, we must reveal its dynamic mechanical properties, thus it is very important to do the comparative study on dynamic mechanical properties of coal and limestone. 

Huang R Q, Wang X N. 1999. Analysis of dynamic disturbance on rock burst. Bulletin of Engineering Geology and the Environment (57) 281-284. 

Li Zhonghua Pan Yishan. 2002. Analytical Solution of Rock burst on Working Surface. Journal of Liaoning Technical University (1) 40 2. 

Pan Liyou, et al. 2006. Practical Technology of Rock burst Forecast and Prevention. Xuzhou China University of Mining and Technology Press 45-60. 

Xie Heping, Pariseau W C. 1993. Fractal Character and Mechanism of Rock Burst. Int.J. Rock Mech. M in, Sci. Geomech. Abstr 30(4) 343-350. 

Zhang Wanbin, et al. 1992. Status and development of rock burst research and prevention in China. Journal of China Coed Society (3) 27-25. 

Coal rock dynamic disasters such as rock burst and coal and gas outburst have always been major problems in coal mining. A lot of researches prove that coal and rock dynamic disaster is a result of coal and rock rupture quickly, being subject to the comprehensive action of stress and the physical chemistry inside and outside the body. Coal/rock undergoing deformation and failure emits many forms of energy, among which is electromagnetic radiation (EMR) (Wang Zhao 2013). 

From the above analysis, it can be deemed that two kinds of EMR emerged in the process of blasting shock wave propagation in coal matrix. One is pulse radiation produced by the impact of coal or rock burst. The other is low frequency radiation caused by the rubbing effect on the coal fracture surface with the shock wave. 

Hazard prediction and prevention of rock burst in island working face... 

PARAMETERS, AND THE EVALUATION OE THE ROCK BURST ORIENTATION OE COAL AND ROCK... 

Processing production of coal sample and physical mechanic parameters test are in strict accordance with the provisions of Measurement method of coal and rode physical and mechanical properties (GB/T 23561-2009), and Measurement method of coal seam impact tendency classification index (MT/T 866-2000). The experiment determined natural apparent density, compressive strength, consistent coefficient, elastic modulus, deformation modulus, wave velocity, rock burst energy index, elastic energy index, dynamic failure time, and other parameters. The determination results as shown in Table 1. 

MICRO SEISMIC MONITORING OF PERCUSSIVE ROCK BURST SOURCES AND ENERGY... 

Micro seismic monitoring system recorded seismic energy of the 2-228 working face is concentrated in between 10 10 j. The article tried to analyze the relationship between seismic energy and the occurrence of rock burst based on. 9 measuring point laid out in 2-228 conveyance road which detected in more than l(Fj of energy of seismic waveform and spectrum characteristics, as shown in Fig. 5. 

As shown in Fig. 5, the rock burst which vibration energy is greater than KFj, its amplitude of main vibration speed is between 0.2 x 10 5.0 x lO m/s, and duration time of signal is between 600 1800 ms. The attenuation is fast, and the higher the energy. 

Through the measurement of coal and rock physical and mechanical parameters, the no. 2 coal seam of Liyazhuang coal mine has medium impact tendency and no impact on the roof strata. Due to stress concentration, hazard of 2-228 island working face is rock burst risk, and the rock burst hazard degree is weak shock hazard. 

Stress concentration, fault activation, goaf roof fracture, goaf roof fracture directly, roof fracture of cutting hole are the main reasons causing weak rock burst hazard of 2-228 Island working face. 

Through the construction of drainage in the coal seam pressure relief drilling and extraction, and water injection before mining, can effectively reduce the chance of rock burst risk. 

Feng Zengchao, et al. 2003. Correlativity of rock in homogeneity and rock burst trend. Chinese Journal of Rock Mechanics and Engineering, 22(11) 1863-1865. 

Li Shulin, 2001. Experimental study of dynamics damage on rock burst tendency. Journal of Liaoning Technical University (Natural Science Edition), 20(4) 436 38. 

Zou Deyun, et al. 2004. Research of energy storing and gestation mechanism and forecasting of rock burst in the coal and rock mass. Journal of China Coal Society, 29(4) 159-163. 

Pan Jun-Feng, Ning Yu, Du Tao-Tao, et al. 2012. The theory and system for preventing rock burst in large-scale areas. Journal of China Coal Society, 37(11) 1803-1809. 

Xia Yong-Xue, Lan Hang, Wei Xiang-Zhi. 2011. Study of comprehensive evaluation technology for rock burst hazard based on microseismic and underground sound monitoring. Journal of China Coal Society, 36(s2) 358 364. 

Research on multivariate hierarchical analysis and evaluation on rock burst hazard... 

In terms of hazard evaluation of rock burst, many researchers have presented different evaluation methods. AE method of evaluating the danger of rock burst is presented (Don L, He X Bernard D. 2000).Weight-variable identification model of comprehensive evaluation on burst liability of... 

Methods aforementioned all have received better effects, nevertheless it is difficult to evaluate rock burst hazard effectively by the presented evaluation methods with increasing of exploitation depth, the major performances are as follows (1) it feels over-theoretical, not-easy to learn, and inconvenient to apply in site (2) Most of these methods are used for macro evaluating for a whole working face or a mining area, while rock burst risk level in different zones of a certain working face is different (3) the evaluation is implemented incompletely, only aiming at one or few influence factors. (4) More static evaluation methods are presented, lack of dynamic simulation evaluation with the process of face mining. 

FACTORS INFLUENCING ROCK BURST AND CORRESPONDING EVALUATION METHODS... 

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