| Coal bump is a phenomenon which release the stress stored in the rock intensely, accompanied by sudden, sharp and violent destruction of coal and rock mass. Amounts of coal bumps in China becomes more than ever since the mining depth and strength are increasing and the geological structures in the underground are more complex. The development and happen of coal bumps are in special geological structures and stratum parameters, and it is a consequence of the steady accumulation of energy and it’s non-steady release during the homeostasis of mining. So it is a composite result of the physical property of coal and rock, geological condition and mining technical conditions. Meanwhile, it has a spatiotemporal evolution characteristic.Yima mining area is a high incidence of bumping mining and coal bump occurred mostly in gateways, and the essence of roadway bump is sudden instability, deformation and destruction of surrounding rock under high stress. Syncline stress, fault tectonic stress, thick overlying conglomerate partial delamination fracture collapse caused by non-uniform stress perturbations roadway and mining are the main factors of roadway bump in Yima mining area. In this paper, on-site investigation, similar simulation test, numerical calculations, and on-site industrial test were adopted to study the roadway bumping mechanism and prevention technology under construction with thick conglomerate coupling conditions.Firstly, statistical analysis of 89 coal bump incidents in 11 typical coal faces in Yima mining area were conducted, and the results show that coal bump in Yima mining area is based on roadway bump, roadways damage was based on floor heave. The similar simulation test has syncline, faults and thick conglomerate geological features of Yima mining area, and digital speckle full displacement field monitoring, stress field monitoring, field monitoring were adopted to study the roadway deformation and failure characteristics under different distance from working face and different distances from the fault, the roadway variation law when activated thick conglomerate separation fracture and fault slip were also analyzed.Secondly, the numerical model which has a syncline, faults and thick conglomerate feature was established to study the impact of mining properties under the influence of roadway syncline role synclinal axis starting from the wing tunnel surrounding rock and impact properties, comparative analysis synclinal axis and wing tunnel surrounding rock impact characteristic similarities and differences; study the impact of mining properties under the influence of roadway faulting, starting from the footwall and the disc mining roadway impact properties, comparative analysis and the footwall disk tunnel surrounding rock impact characteristic similarities and differences; study the impact of mining under thick conglomerate effects impact properties of tunnel surrounding rock, gravel thickness under different conditions from a comparative analysis of the impact of mining roadway characteristics; study the impact of mining construction and thick under the combined effect of tunnel surrounding rock conglomerate shock feature, the same time in different places at different distances pitch face mining roadway impact properties, the same place at different times at different distances from the working surface of tunnel surrounding rock from the fault analysis and impact properties of different a detailed analysis of the impact of distance tunnel surrounding rock properties respectively, deriving the roadway bumping mechanism under construction with thick conglomerate coupling conditions.Finally, the roadway integrated control system and specific control measures of Yima mining area was put forward, and mining roadway strong flexible support system, U-shaped steel joint support system and bolting system were evaluated. Meanwhile, according to the mining roadway impact pressure indications law, the strong flexible support system is suitable for roadway anti-punch supporting in Yima mining area. Specific research results are as follows:1. Based on Yima mining area coal and rock engineering geological characteristics and the results of the impact test measures, statistical analysis of 89 coal bump incidents in 11 typical coal faces in Yima mining area were conducted, the results show that 29 times driving coal bump accounted for 32.6%, to a total shock pressure recovery occurs 59 times, accounting for 66.3%, the pressure of other places there were an impact, accounting for 1.1%, so Yima mining area coal bump pressure recovery to be the main shock, but boring coal bump must be given adequate attention; face coal bump were 9 times, accounting for 10.1%, roadway bumping were 80 times, accounting for 89.9%, so coal bumps in Yima mining area are based on roadway bumps. Combined with the timing and location, we could draw that Yima mining area coal bumps are based on mining roadway coal bump, there were 51 times, accounting for 57.3%; thick conglomerate partial delamination fracture collapse caused by non-uniform force roadway lane is induced under pressure mainly due to the impact of land; the impact of mining roadway deformation caused damage mainly to the kick drum and removed along with the help lower bulging shoulders help other damage; Yima mining area stoping bumping impact occurs the main factors syncline stress, fault tectonic stress, thick overlying conglomerate partial delamination fracture caused by non-uniform stress caving roadway and mining disturbance.2. The similar simulation test which has a syncline, faults and thick conglomerate feature was designed to study immediate roof caving mining face and broken roof variation. The results show that the direct roof first collapse step was 35 meter, caving height was 2 meter, roof first collapse step was 85 meter, caving height was 66 meter, and the thick conglomerate roof caving height has been extended to 90 meter. The thick conglomerate variation of fracture separation was also got, when the mining face was advancing 90 meter, thick conglomerate in the role of the overburden load, partial collapse occurred separation, the separation range was 20 meter, caving height extended to 110 meter; we also get activated fault slip variation, when the mining face was advancing 95 meter, slip faults have lost steady signs; fault-prone areas are broken slip instability border zone, the immediate roof area and roof area; fault slip instability exacerbated tunnel surrounding rock deformation, especially in the first activation of the fault slip, the floor heave deformation more serious, or even the impact of roadway floor.3. Through research the whole phase transformation rule of the roadway surrounding rock, the rule of variation distance from the work face to the surrounding rock, the rule of roadway country rock in a variation of distance to the fault different, the rule of roadway surrounding rock transformation when the thick conglomerate delamination fracture and when fault slip activated, and then obtained the following rules:(1) the fault activation slip phase on the recovery; the stage when roadway displacement greater than the thick conglomerate fracture separation; roadway energy field changes tended to increase with face advancing; when mining 70 meter, roadway energy accumulation is larger; when mining 85 meter, roadway large energy release; mining 95 meter, the roadway sharp energy release; 28 meter from the mining face to the fault, the fault occurs instability, slippage and activation, sharp energy release roadway, roadway deformed mutant bass drum performance, roadway completely destroyed, and even the floor impact.(2) the roadway distance from the working surface area is greater than 50 meter is the impact show zone, but the roadway deformation is small; the roadway from the working surface area of 10~50 meter is the significantly affected areas, roadway deformation of a substantial increase; the roadway from the working surface area of less than 10 meter is the roadway mutations affecting area, surrounding rock deformation increased dramatically, and even increase the mutation, the floor heave deformation performance is particularly prominent.(3) 20 meter away from the footwall, the most serious roadway country deformation; roadway deformation under the mining influence, along with distance disk fault distance decreases increases slowly at first, and then a sharp increase in non-linear, and finally mutation increases, especially the performance of the floor heave is more obvious; roadway roof and floor deformation significantly greater than the two groups deformation, where the floor heave most serious and the fault side deformation followed.(4) footwall coal and rock’s displacement and velocity was significantly greater than the fault closer to the plate, footwall fault roadway deformation is significantly greater than the disk; activation of fault slip under the influence of mining, the most serious deformation of roadway is floor heave, right side deformation to the second, the roof sink and left side closer is smaller.4. Establish the numerical models has syncline, faults and thick conglomerate feature, using 3DEC, FLAC3 D and CDEM numerically calculated and get the following rules:(1) under the influence of mining synclinal axis roadway deformation dominated by floor heave, syncline wing deformation of surrounding rock bottom and two sides are at the same time; the whole roadway deformation of synclinal axis section is greater than the syncline wings, which synclinal axis section of the floor heave of about 2 times of syncline wings; the depth of 1~3 meter in synclinal axis roadway floor surrounding rock deformation is severely, the depth of 5~8 meter of country rock bottom is more stable, and syncline wing deformation of surrounding rock roadway floor in 1 meter depth was significantly greater than the surrounding rock bottom in 2~8 meter depth, and 2~8 meter depth of surrounding rock in floor deformation with linear variation.(2) near the footwall rock stress is easier to transfer than the dish stress on the fault; stress after the footwall rock stability is less than the plate; energy surrounding near the footwall is easier than footwall to accumulate and release; roadway rock in the floor and two sides release of energy is the most obvious, the footwall instantly change the energy surrounding rock bottom margin of 1500 KJ/m3, significantly greater than the plate energy with the instantaneous change in the magnitude of 914 KJ/m3, about 1.5 times of the footwall energy release; plate roadway plastic zone to expand the mainly on the floor, gradually expand to the left, tray roadway on the fault plastic zone also expanded mainly on the floor, but expand gradually to the right side; footwall roadway floor heave maximum of 1.83 meter, was significantly greater than floor heave on the tray which maximum deformation is 1.04 meter, about 1.8 times of the tray floor heave; 1~3 meter depth roadway floor surrounding rock deformation is seriously, floor 5~8 meter depth country rock is stable.(3) after roadway country rock stabilizing under the impact of mining and thick conglomerate, when conglomerate thickness is 50~190 meter, the left side rock stress value is greater than the floor surrounding rock, the sides prone to impact, when conglomerate thickness is about 260~400 meter, the left side rock stress value is less than the surrounding floor rock, bottom shocks easily occur; roadway floor surrounding rock vertical stress and horizontal stress when thickness among 50~190 meter conglomerate fluctuated changes, and the stress is small, when the conglomerate thickness among 260~400 meter the stress increases rapidly, and finally stabilized at a high stress state, the maximum stress values were 42 MPa and 37 MPa.(4) under co-function of the mining impact, structure and thick conglomerate, surrounding rock stress in mining roadway presents "几" shape distribution; roadway floor surrounding rock and the energy in right side presents "一" shape distribution, surrounding rock prone to impact; roadway roof and left side rock energy show "厂" shape distribution, the surrounding rock is less prone to impact.(5) with the roadway floor surrounding rock with the distance from the working surface, the level stress on the surrounding rock control the deformation, and because of the large range of horizontal stress release, easily lead to the floor coal bump, the level of the floor of the deep rock stress play a key role in the control of surrounding rock deformation, after 1~3 meter depth floor rock mutated, the stress was significantly lower than 5~8 meter surrounding rock stress; decreases with distance from the working surface, the level of rock stress play a key role in controlling on the whole, the vertical stress play a supporting role.(6) roadway roof, floor, the right side wall rock energy reduce changed little with the distance reduce from the fault, and the magnitude is lower, the energy value of the floor almost to zero; left side of roadway surrounding rock energy with the reduce to the fault, reduce after a small initial increase, then high, then low, the last mutation increases, the distance of 50 meter to the fault is the minimum point, 20 meter distance to the fault is the minimum point mutation; with the decreases of distance from the fault, the roadway floor 1~3 meter depth’s energy below floor surrounding rock of 5~8 meter; with decreasing distance to the fault, roadway deformation increase is nonlinear, even abrupt mutations, especially in the more obvious manifestations of the floor heave, roadway floor 1~3 meter depth more intense deformation of surrounding rock, country rock bottom 5~8 meter depth more stable, less the amount of deformation; when 60~100 meter from the fault roadway deformation appear; roadway from the fault appeared 20~60 meter significant roadway deformation; roadway from the fault 10 ~20 meter roadway deformation mutations appear.5. Proposed structure and thick conglomerate under coupling function conditions roadway rock burst mechanism, namely the impact of mining or under dynamic loading, complex tectonic stress release is mainly caused by mutations in the surrounding rock levels stress increase, it is first transferred to the fault side, but with the side support intensity is usually higher, and therefore stress quickly transferred to the base plate and the accumulation of large amounts of energy, when the energy accumulated larger to capacity of consumption and the limit of coal wall strength energy, the floor that surrounding rock strength and support of their own strength are low is the best place to release their energy, so sharp instability surrounding rock, deformed, or destroyed, triggering the floor impact.6. Proposed Yima mine mining roadway integrated control system and the impact of specific prevention measures, and mining roadway strong flexible support system, U-shaped steel joint support system and bolting system for the total evaluation, application practices are based on the recovery roadway coal bump omen law, drawn strong support system of flexible anti-red roadway at key control action of surrounding rock stress field, the energy field and displacement field is significantly better than the U-shaped steel joint support system and bolt support care system, and can be a good fit and control of surrounding rock deformation, play an active and significant role in structural coupling with thick conglomerate mining roadway under bumping prevention and control. |
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