| The 14th Five-Year Plan regards coal as a "backstop" in the country’s energy supply as a link to strengthen national economic security.China’s coal production and consumption exceeded half of the total world production and consumption in 2020,but since January to October 2021,the general rise in power coal prices has led to an increase in the cost of raw materials for coal-fired power plants,and the power shortage since late September has led to the off-peak production and suspension of production in some enterprises.The National Development and Reform Commission,the State-owned assets Supervision and Administration Commission of the State Council,the National Energy Administration have put forward a number of measures to increase coal production and increase supply,and the daily output of coal dispatching has reached a new high on November 10.On December 5,many departments at the National Coal Fair decided to ensure a stable supply of coal in 2022 and beyond.More and more mining areas extend to the deep,and the geological structure is becoming more and more complex.the grouting technology of broken coal and rock mass,coal pillar reinforcement and other grouting control projects used in roadway surrounding rock control will consider more and more the threat of gas outburst,rockburst,water damage,heat damage,dust and other disasters and the role of dynamic loads such as drilling and anchor construction,blasting vibration,mechanical tunneling,mining and so on.Taking the grouting measures of a coal mine roadway in Wangwa,Ningxia as the background,the dynamic mechanical characteristics of broken coal and rock mass after cementation reinforcement are studied.On the basis of sieving coal particles in four particle sizes(0-2.5mm),(2.5-5.0mm),(5.0-7.5mm)and(7.5-10.0mm)to simulate the crushing degree,the dynamic compression test and dynamic splitting tensile test of cemented bodies were carried out.Based on this,the time history curves of stress,strain,strain rate and energy,stress-strain curves and macroscopic crushing morphology of the samples were analyzed.The main conclusions are as follows:1)in the dynamic compression test,the pressure increases with the approximate quadratic function relationship between the strain rate and the strain rate;with the increase of the strain rate,the dynamic compressive strength increases approximately linearly by 263.41%.The dynamic elastic modulus and peak strain increased by 257.01%and 121.02%respectively.With the decrease of the crushing degree of coal particles,the dynamic compressive strength,dynamic splitting tensile strength,dynamic elastic modulus and loading rate tend to decrease,while the peak strain and strain rate tend to increase.The crushing degree of the sample increases with the decrease of the crushing degree of coal particles and the increase of air pressure.2)in the aspect of dynamic compression energy dissipation,the incident energy is approximately positively correlated with the air pressure,the absorption energy and reflection energy also increase linearly with the incident energy,and the transmission energy increases approximately quadratic function with the increase of incident energy.the ratio of energy absorption and strain rate shows an approximate quadratic function increase by 1028.57%.With the decrease of the crushing degree of coal particles,the incident energy may remain unchanged,the transmission energy and absorption energy decrease,while the reflection energy increases.3)in the dynamic splitting tensile test,the variation of energy with air pressure and particle size range is similar to that of dynamic compression test,and the loading rate increases with the increase of air pressure.the dynamic splitting tensile strength and specific energy absorption of the sample increased by 58.45%and 779.17%respectively.When the air pressure increases,the crushing degree of the sample increases,but when the crushing degree of coal particles changes,the crushing degree of the sample does not show obvious change.Figure 40 Table 15 Reference 70... |
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