| The parameters of natural rock and soil show spatial variability due to different sedimentary environment and tectonic action.It is advisable to describe it by random field theory.A lot of scholars have introduced this theory into geotechnical engineering research,but few researches on the spatial variation of mechanical parameters of coal seam floor from the perspective of random field and discusses the reliability of coal seam mining system based on this.Therefore,this paper intends to study the rock parameters modeling along the ground floor and the reliability of mining system by carrying out the numerical simulation of coal seam mining under the random condition.The main results are as follows:1)The random field of rock mass parameters should be simulated based on Gaussian random field.The common methods include local average method.covariance matrix decomposition method,moving average method and circular embedding method.The results show that the simulation of random field by moving average method has strong isotropy,but the discrete range is far greater than the correlation distance;the local average method and covariance matrix decomposition method are time consuming,while the simulation efficiency of moving average method and circular embedding method is more than 100 times faster than the former two;the accuracy of local average method is higher than that of other methods.Considering the difficulty,efficiency and accuracy of the results,the circular embedding method is the best choice when the precision is satisfied.2)The results of mining simulation based on monte carlo method are as follows:?When the rock parameters of the floor are random,the failure form is consistent with the fixed value,but the failure range is relatively discrete compared with the fixed value.?When the rock mass parameters are random variables,the horizontal and longitudinal distribution of rock mass failure is consistent,and shows a certain randomness;when it is random,the longitudinal distribution is larger than the transverse,the vertical variation is stronger,and the control function of the random field is obvious.?The influence of random field on hard rock failure is weaker than that of soft rock,and the failure of soft rock is relatively high discrete,while hard rock is lower;for layered floor,the failure of upper soft and lower hard type is sudden change at the lithological interface,and random failure will occur in the upper hard and lower soft rock area.In practice,attention should be paid to.?When the correlation distance changes,the failure probability of rock mass is basically the same in macro,and the failure probability varies with the simulation times under different correlation distance.However,for the same point,the failure probability decreases with the increase of correlation distance.3)Taking the floor mining failure of No.10 coal seam in Taoyuan coal mine for example,based on the monte carlo principle,the risk of water inrush caused by floor mining failure is simulated under the conditions of coal seam mining depth of 650m,limestone aquifer water pressure of 2.5MPa and mining depth of 750m,limestone aquifer water pressure of 3.5MPa.Compared with the water inrush coefficient method,the numerical simulation technology considering the spatial variation of parameters is obtained,and the rock mass parameters are fully considered The impact of heterogeneity has high credibility.The water inrush coefficient and reliability probability can be used as evaluation indexes in the determination of floor water inrush,which makes the determination result of floor water inrush risk more accurate and comprehensive.Figure[68]Table[12]Reference[102]... |
PDF Full Text Request