Plane Contact Type Of Structure And Stability Mechanisim In Strata Over Working Site

The type of block structure in strata over working site is one of important content in strata control researching in mining. In this thesis, it is made to study systematically on the mechanic characteristic of plane contact block structure by using the method of mechanics analysis, and the transmit law of force in this kind of block structure is acquired, the stability requirements of the structure is given. And at the same time, the relationship between the structure stability, the geometry parameters of blocks and the angle of structure deflection is discussed. Based on the theoretical research, the laws of maximum main stress distributing and the effect of proportion of block length and height to block breaking are analyzed with the method of numerical simulating. The analyzing results indicate that the load-bearing capacity stems from arch structure effect. The outcome of numerical imitation also makes it clear that the block is not fit for point-point contact form as the proportion of length and height is little than 1. To counter the characteristic of plane contact, three contact plane parameters such as roughness coefficient, wall compressive strength, and basic friction angle, are applied to describing the anti-friction property of contact plane of blocks. And the anti-friction pattern of damaged face in strata above working site is drawn from experiment data. It is proved by test that the numerical values of these three parameters are changed with the changing of compressive stress on the contact plane, and therefor lead to friction coefficient changing of the plane.Another important problem is the transmit law of stress in damaged strata when strata control researching of working site is in progress. This transmit law is the base of load defining of block structure in damaged strata. With the aid of broken stone theory, the block medium model is set up, and the transmit law of weight stress in blocks is studied, the average stress calculating formulas are summarized. All of these provide assistance for structure load calculation of lower basic roof stratum.As theory applying, the underground pressure calculating method of working site based on plane contact block structure in lower stratum of basic roof is probedbeneficially, and the relevant formulas are given. Meanwhile, the effects of contact face parameters in damaged rock stratum for pressure strength, the relationship between angle of basic roof structure and roof subsidence in controlled area at working site, are researched.In brief, this thesis studies the block structure from plane contact angle firstly, has set up theory frame of plane contact block structure in basic roof strata preliminarily for underground pressure researching of working site, and has laid a well foundation for further studying of this kind of block structure.