Informatics Publishing Limited

Feng Xiao ¹, Zhuo Yulong ¹, Chen Xin ¹, Wang Xiaojun ¹, Zhong Wen ¹

Affiliations
1 Jiangxi Key Laboratory of Mining Engineering, School of Resources and Environment Engineering, Jiangxi University of Science and Technology, Ganzhou Jiangxi-341000, CN

Abstract

An effort is made to study the mechanical features and AE characteristic parameters of filling bodies under repeated loading and unloading, which are common stress paths for the filling bodies of mine, to providing theoretical basis for the monitoring and the bracing of backfilled mine. Material testing machine RMT-150C is used to conduct uniaxial compression experiments on cemented filling body under above mentioned stress paths and 1MHZ broad-band emission sensor is employed to collect AE parameters prior to the arrival on peak compression strength. The results indicate that comparing to monotonic loading, cyclic loading could elevate the peak stress of filling bodies by about 30%. The stress-strain-accumulative AE number curves of specimens under cyclic loading tells the surge of accumulative AE number on specimens’ reaching peak stress, which combining with test process proves the thorough failure of filling body. It is then demonstrated that the surge of accumulative AE number could serve as a reference criterion for judging the failure of filling bodies.

Keywords

Cyclic Loading, Filling Body, Mechanical Feature, Acoustic Emission.

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Tao Tiejun ¹, Huang Ping ², Chen Xin ³, Chi Enan ¹, Zhang Jianhua ⁴, Zhong Wen ³

Affiliations
1 Guizhou Xinlian Blasting Engineering Group Co., Ltd., Guiyang Guizhou-550002, CN
2 College of Environment and Resources, Fuzhou University, Fuzhou Fujian-350116, CN
3 Jiangxi Key Laboratory of Mining Engineering, School of Resources and Environment Engineering, Jiangxi University of Science and Technology, Ganzhou Jiangxi-341000, CN
4 Wuhan University of Technology, Wuhan Hubei-430070, CN

Abstract

In order to increase the accuracy of rock blast-ability classification, the comprehensive evaluation model of rock blast-ability classification was established based on uncertainty measurement theory by eight factors including rock density, tensile strength, impact strength, integrity coefficient, compressive strength, sturdiness coefficient, wave impedance and explosive specific charge. The uncertainty measurement function was obtained based on the in-situ data; entropy theory was used to calculate the index weight of all indexes, and the comprehensive evaluation results of rock blast-ability classification were obtained using the rules of credible recognition criteria. In order to optimize the blasting design, the evaluation model was used to evaluate the rock blast-ability in Guiyang Chaoyangdong road engineering and the evaluation results fit in anecdotally with actual situation. Therefore, the evaluation model was a significant basis for promoting the blast effect.

Keywords

Rock Blast-Ability Classification, Uncertainty Measurement Theory, Information Entropy Theory, Believing Degree Criterion.

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Wang Yang ¹, Tao Tiejun ¹, Chen Xin ², Chi Enan ³, Zhao Mingsheng ³, Zhou Jianmin ³, Zhong Wen ²

Affiliations
1 School of Civil and Environmental Engineering, University of Science and Technology, Beijing-100083, CN
2 Jiangxi Key Laboratory of Mining Engineering, School of Resources and Environment Engineering, Jiangxi University of Science and Technology, Ganzhou Jiangxi-341000, CN
3 Guizhou Xinlian Blasting Engineering Group Co Ltd, Guiyang Guizhou-550002, CN

Abstract

The fractures in rock influence propagation behavior of blasting waves and then it may result in higher blasting boulder yield and affect blasting result. According to the character of rock with closed macro fractures, the features of stress wave propagation in the rock with one inclined fracture, two parallel fractures and two crossed fractures were studied. The numerical models were established in 3DEC combined with LS-DYNA. The explosion wave was simulated by LS-DYNA and transformed into data form readable for 3DEC. Then the propagation behavior of blasting wave was calculated by 3DEC. The computation results show that the stress wave distributed differently in rock with different fractures. Comparing with intact rock, fractures can divide the stress region into parts. The minimum principal stress reduced quickly with the number of fractures increasing. In rock with two crossed fractures, the value of tensile stress near the blasthole reduced about 30 percent.

Keywords

3DEC, LS-DYNA, Wave Propagation, Fractures, Stress Distribution.

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