(1) System of interaction between support and surrounding rock The support of the mining face and the surrounding rock supported by it are a pair of interacting contradictions. The design of the structure and performance of the support must conform to the law of surrounding rock movement of the mining face. Only in this way can the design of the support structure be economical and reasonable. At the same time, only the support force distribution of the bracket is appropriate, and the roof protection device is reliable, it is possible to maintain the top plate to ensure the safety of the miners and the normal production. (2) Characteristics of the interaction between the support and the surrounding rock The characteristics of the relationship between the mining face support and the surrounding rock are as follows: (1) The bracket and surrounding rock are a pair of forces that interact. In a small area, the roof pressure formed by the surrounding rock can be regarded as a force, and the bracket can be regarded as a reaction force. The two should be adapted to each other to make them equal in size and act as much as possible at one point of action. (2) The size of the support and its distribution on the mining face are related to the performance of the support. It has been proved that the distribution of the rigid, sharp-increased, micro-resistance or constant-resistance brackets on the working surface is inconsistent, and the stress of the constant-resistance bracket is relatively uniform. (3) The influence of the structure and size of the bracket on the pressure of the roof. In actual production, it is proved that the top plate can be maintained with a minimum working resistance when the bracket type is properly selected. For example, under some conditions, the short-beam shield bracket (the strut working resistance is only 800kN) can achieve better maintenance than the four-column type (working resistance 2400kN). It can be seen from the above situation that the design of the support structure must be adapted to the surrounding rock conditions, and the performance of the support should be designed as a constant resistance as much as possible. The force of the support should be consistent with the pressure of the top plate during the process of the support. The most important factor in the stent parameters is to determine the working resistance and shrinkage. For the surrounding rock, it is mainly considering the state of the roof under the action of various brackets, which leads to the quality standard of assessing the integrity of the surrounding rock. (3) Relationship between the working resistance of the bracket and the amount of roof subsidence As early as the 1960s, the test of the relationship between the working resistance P of the support and the final sinking amount ΔL of the top plate was repeatedly performed at home and abroad. China was carried out in the laboratory at that time. Some countries used statistics based on on-site measured data. The most complete one was that the former Soviet Union conducted a stent pressure test on a working surface. The results were roughly the same as those obtained in the laboratory, which proved the work. The resistance P and the final sinking amount of the top plate (ie, from the coal wall to the side of the goaf) are an approximate hyperbola, or "P-△L" curve. Test conditions were: cutting height 1.3 ~ 1.5m, angle 2 ° ~ 3 °, the immediate roof of about 5m siltstone, compressive strength 73MPa; siltstone still further above, but denser, compressive strength of 81 - 82.6 MPa; using a supported hydraulic support. In the pressure test, the working resistance of 1500kN per frame was initially used and then adjusted to 1300kN/frame. This is the first stage of the trial. In the second phase, it is adjusted to 1000kN per frame. Finally, adjust the bracket to 600kN/rack. Each stage has undergone a cycle to pressure and normal two processes. Table 5-4 presents the data from the trial. Table 5-4 Table of each stage of the pressure regulation test All the above statistics and test results prove the fact that, above a certain working resistance, the increase of the working resistance of the bracket has little effect on the sinking amount of the roof, but below this value, the impact is extremely great. From this, the same conclusion can be obtained in the above analysis that the working resistance of the stopway bracket does not change the overall activity law of the overburden. For Sugar Industry Chemical Pumps Chemical Injection Pump,For Sugar Industry Chemical Pumps,High Reputed Pump,Stainless Chemical Pump Sichuan Zigong Industrial Pump Co.,Ltd. , https://www.zgpump-global.com