The overall failure of gas-bearing coal–rock composite is the main cause of composite dynamic disasters. Investigating the mechanical-seepage characteristics of coal–rock specimens is the key to understanding the mechanism and minimizing composite dynamic disasters. In this paper, true triaxial mechanical experiments are designed and conducted under different maximum principal stress-loading rates. The mechanical properties, strength characteristics, and energy responses of samples under different loading rates are studied. A damage constitutive model of coal–rock specimens under different true triaxial loading rates is established; the solving methods for micro strength parameters m and F0 are described. The results show that as maximum principal stress-loading rate increases, the bearing capacity of the sample increases, the deformation parameters gradually increase, the degree of energy change increases, and the deformation failure becomes more severe. The model of gas-bearing coal–rock specimens under different true triaxial loading rates is in agreement with the test curves. Our model can provide useful references for predicting the stability of underground gas-bearing coal–rock.

In deep mining, coal-rock is in a state of three unequal forces, and the intermediate principal stress has the influence on the deformation and strength characteristics of coal-rock. This study studied the deformation and seepage characteristics of gas-bearing composite coal-rock under different intermediate principal stresses by using true triaxial gas-solid coupling seepage test device for coal and rock. The results show : ① With the increase of intermediate principal stress, the strain in the direction of maximum principal stress first increases and then decreases when the peak strength is reached, and there is widening gap between the strain in the direction of intermediate principal stress and the strain in the direction of minimum principal stress.② Under low intermediate principal stress, the strain in the intermediate principal stress direction shows expansion and deformation, and when there is relatively high intermediate principal stress, the ε2-Δσ curve reaches the peak and then bounces back, and the strain in the intermediate principal stress direction finally shows compression and deformation.③ With the increase of intermediate principal stress, the trough value of relative permeability coefficient decreases, and the peak inflection point of relative permeability coefficient curve is consistent with the inflection point of ε1-Δσ curve.④ When the stress peak is reached, the total input energy of the specimen first increases and then decreases, which is similar to the changes of the specimen strength: The elastic strain energy first increases and then decreases, the dissipative energy continues to increase, Ue/U first increases and then decreases, and Ud/U first decreases and then increases.

Coal will still be China's basic energy for quite a long time. With the increase of mining depth, gas content and pressure also increase. The problems of gas emission and overrun affect the safety and efficient production of coal resource to a certain extent. In this work, the field test of gas drainage borehole peeping and trajectory measurement in coal seam of Changling coal mine are carried out. These coal seams include C-5(b) coal seam, upper adjacent C-5(a) coal seam, C-6(a) coal seams, C-6(C) in lower adjacent strata, and C-5(b) coal seam in high-level borehole. The view of gas drainage borehole peeping and trajectory measurement in the working seam, upper adjacent layer, lower adjacent layer, and high position are obtained. It is found that the hole collapses at the position of about 20 m in both adjacent strata and high-level boreholes, and there are a lot of cracks in the high-level boreholes before 12 m. The deviation distance of high-level borehole is large, and the actual vertical deviation of upper adjacent layer is small. Finally, the strategies to prevent the deviation of drilling construction are put forward. It includes four aspects: ensuring the reliability of drilling equipment, reasonably controlling the drilling length, standardizing the drilling, and reasonably selecting the drilling process parameters.

Based on the combination weighting method and grey correlation method,a new TOPSIS evaluation model is proposed,and the compressive strength of rock burst was evaluated.The influence factors affecting rock burst,including uniaxial compressive strength of rock burst strength σc,tensile strength σt,the maximum shear stress σθ and elastic energy index ωet and other factors were reflected in the model,and the σθ/σc,σc/σt,and ωet were taken as the evaluation indexes.Based on combination weighting method,we use triangular fuzzy function and entropy method to obtain the subjective and objective weights,and distribute them to these indicators,and then use related functions to characterize the correlation between samples and positive and negative ideal points,the ideal points are different rock burst intensity correlation coefficient can be calculated.The relative coefficients of the positive ideal points for different compressive strength of rock burst can be calculated.According to the maximum correlation coefficient,the prediction result of rock burst is in good agreement with the actual situation in the field.

Taking the roof fall accident caused by small fault structure in 20322 belt roadway in Wangjialing Coal Mine as the engineering background, field investigation was carried out on the the roof deformation and failure characteristics before the roof fall and the characteristics of the fall zone height after the roof fall, and based on this, analysis was made on the bed separation of the roof with different lithology by using RFPA numerical software. The analysis results showed that with the increase of the roof strength and stiffness, the roof stability was significantly improved. The technology of using the high pre-stressed multi-cable truss system to control the roof stability was proposed and analysis was carried out on its control effect and rational support parameters from the angle of mechanics. After the implementation of the symmetric support scheme by "multi-beam anchor cable reinforced composite", 6 places where the roof was rather broken were selected for strata control observation, the observation results showed that the roof control effect was good.

针对目前煤矿隔爆型或者隔爆兼本安型计算机质量重,使用维护不便等问题,提出设计一种带有数据采集功能的矿用本安型计算机,介绍了该计算机系统设计,并提供了本安保护、数据采集、信号隔离等关键电路设计实现过程.

In order to provide a theoretical basis for the deployment posistion of dust concentration sensors in working face of coal mine,the geometry model of mining face roadway was established.Based on the protion equations of gases and dusts,and the discete phase model in the Euler-Lagrange method,the distribution conditions of dust in the underground mining face and return airway were simulated by fluent.The results showed that:the dust concentration reaches the maximum ralue at the position of 10-20m behind the driver,and it tends to be stabilized at the position of 30m the sensors of dust should be placed in the position of less than or equal to 10m from the fully-mechanized mining face of the return airway.

In order to achieve environmental noise monitoring of underground,developed mining noise level sensor.Describes noise level sensor design,circuit and main technical indicators,and gives key process circuit,noise using a sound level meter to compare test results show that sensor has a easy to use,measurement accuracy,etc.advantages,with good promotional value.

In view of noise hazard of coal mine underground, the paper proposed a design scheme of noise measuring instrument based on STC single-chip microcomputer, and introduced hardware and software design of the instrument. The test results showed that the instrument realizes accurate measurement of noise level, measurement error is less than ±1.25%, which reaches 2-level of sound level meter.

The aim is to develop a new sensor for measuring the consistence of coal dust via the charge method.Based on the static test theory,the experimental systems are applied to research into the rod-like,inner ring-like,and outer ring-like probe to generate the charge in different consistence of coal dust,and find out the suitable probe for the mine so as to see how different wind velocities and dust particle sizes affect the generated charge for this probe.It is concluded that,for the 3 types of probes,as the consistence of dust increases,more charges are generated,and their relationship is linear;and among the 3 probes,the rod-like probe is the most sensitive and so is more appropriate to measure the consistence of coal dust in the mine.Meanwhile,the experiments have been done to the rod-like probe under different wind velocities and different dust particle sizes.The result shows that,if the wind velocity is different,the linear relationship between the consistence of dust and the generated charge is different;in the scope of 5~7 m/s,the higher wind velocity,the better linear relationship,and the more helpful to accurately measure the consistence of dust;change of particle sizes doesn′t greatly affect the rod-like probe's measuring the consistence of the coal dust.

The invention discloses an intelligent dust concentration limit setting spray dust settling device. The device comprises a control unit, a dust concentration sensor, an electromagnetic valve and a sprinkler head, wherein the signal output end of the dust concentration sensor is connected with a signal input end of the control unit; a control signal output end of the control unit is connected with a control signal input end of the electromagnetic valve; and the control unit realizes spray control over the sprinkler head through the switching of the electromagnetic valve. In the device of the invention, the dust concentration limit is manually set; the spraying starts when the dust concentration limit exceeds an upper limit value and stops when the dust concentration limit is less than a lower limit value; and thus the meaningless waste of water resource is prevented, the water logging in roadways is reduced, the working conditions are improved and the health and the safety of mine workers are ensured. In addition, the invention also discloses an intelligent dust concentration limit setting spray dust settling system, so the remote on-line monitoring of the dust concentration can be realized; meanwhile, the invention also discloses an intelligent dust concentration limit setting spray dust settling method.

This paper introduced a new measurement of dust concentration method—induced charge method.It designed the experimental test device,established the experimental platform,researched the dust concentration and the relationship between induced current by outer induced charge method.The experimental results show that the concentration of dust generated by their linear relationship between induced current,wind speed,dust measurement of particle size on the charge of dust concentration affect the greater the wind speed,the smaller the particle size,the greater the induced current generated.

介绍了沉积粉尘传感器的原理和结构,重点阐述了称重传感器信号高精度A/D转换电路的设计和电路抗干扰措施的应用,通过在阳煤集团新景矿的现场试验,证明了研制的沉积粉尘传感器可以与KJ90等安全监控系统联网使用,测量误差小于5%。

To counter the essential component-PMT used in dust measurement,analysis and study were made on this component.Through analysis and experimental study on the characteristics such as operating time,reference voltage,temperature and magnetic field of PMT,it is concluded that the PMT output was tending towards stability with the increase of operating time of it dust measurement system;different reference voltage had different stability;the output voltage of PMT decreased slightly with temperature rise;and magnetic field had sensitive influence on the sensitivity of PMT.These conclusions can provide basis for the design of hardware and software in dust measurement system,and also offer reference for the application of PMT in other aspects.

According to the classic Mie ray scattering theory, the scattering characteristic curves of a single dust particle was analysed and computed and the scattering characteristics of dust cloud was studied experimentally. The influence on ray scattering caused by scattering angle, particle size distribution and fog was studied. Scattering luminous intensity of a single dust granule increases with increase in pellet particle size but for a dust cloud if the diameter increases, the sensitivity becomes more sluggish and the dust concentration value obtained is somewhat lower. 4 refs., 5 figs., 2 tabs.

通过试验对长平煤矿的未浸泡煤样和用水浸泡煤样的产尘能力、煤破碎性指标、煤破碎程度指标及呼吸性粉尘在粉尘中含量进行测试和计算,分析得出浸泡煤样在产尘能力和呼吸性粉尘在粉尘中含量等方面均比未浸泡煤样有所下降,可为煤体注水防尘提供参考。