A deformation measurement method based on surface texture information of rocks and its application

Users of the digital image correlation method are faced with the problem of poor operability,low repeatability,and lack of standardized specifications for spraying speckles.To solve the problem,the research proposed a rock deformation measurement method that obviates the need to spray speckles.A local binary model was established by using the local binary pattern(LBP)operator based on deep texture features on rock surfaces.The resulting LBP digital speckle pattern can substitute artificial speckle patterns and demonstrates high quality and strong applicability.Based on the LBP digital speckle pattern,the target tracking algorithm was employed to achieve non-contact measurement of the dynamic displacements of rocks.The feasibility and effectiveness of the algorithm in practical application were verified by conducting shear tests on granite and siltstone.Test results show that the deformation characteristics in the displacement nephograms are in line with the measured data pertaining to rock fracturing and conform to the basic characteristics of the shear failure of rocks.The deformation measurement method based on surface texture information can realize non-contact displacement measurement of rocks under conditions without speckles:this obviates the influence of the quality of sprayed speckles on the accuracy of the measurement of deformation.

Floor heave mechanism for gob-side entry retaining with concrete blocks and control method:A case study

The issue of significant floor heave deformation in gob-side entry retaining has long been a challenging problem in the context of longwall mining.This paper studies the floor heave failure mechanism and control method for gob-side entry retaining with concrete blocks in Guizhou Faer Coal Mine in China.Based on Rankine’s earth pressure theory,the effective shear stress equation for the plastic slip of roadway floor is established.The deformation mechanism of floor heave in a retaining roadway with a block wall is revealed in this study.The new comprehensive control method is proposed,encompassing roof pre-splitting blasting for pressure relief,reinforcing cables for roof control,double directions control bolts for concrete block,and pliability cushion yielding pressure.FLAC3D numerical calculation model is established,which shows that the new method can effectively reduce the average vertical stress peak value of the entity coal floor by 34.6%and significantly reduce the pressure source causing the roadway floor heave.Besides,a multi-parameter real-time online monitoring system for mine pressure was designed,and field tests were carried out.The results show that the maximum value of roadway floor heave under the new method is 163 mm,reduced by 66.9%,and the roadway floor heave is effectively controlled.These research findings offer a fresh perspective and new ideas for controlling floor heave in mining operations.