Theory And Performance Optimization Study Of The Wet Chord Grid Water Film Purify Of The Fine Particles Dust

The Permian Longtan Formation is the primary coal-bearing strata in southwest China,one of the country’s significant coal-bearing regions.Mudstone makes up the majority of the Longtan Formation’s lithology.The Longtan Formation’s mudstone dilatancy properties were primarily examined in this paper,along with roadway dilatancy boundary’prediction techniques and mitigating factors.On-site mining investigations,rock mechanics tests,theoretical analyses,and numerical simulations were used in the research.Laboratory experiments had established the parameters of mudstone dilatancy variation rules.A coupled stress calculation model for roadway excavation stress field and coal seam mining stress field was created.The theoretical expression of bearing arch thickness is derived,the evolution mechanism of stress dilatancy boundary under various circumstances,and the dilatancy boundary equation of surrounding rock in two-way unequal pressure roadway.The deformation control key measures were put forth.The pertinent findings can aid in making decisions on the engineering design of roadway supports.The following are the paper’s key research findings:（1）It is found that mudstone dominates the lithology of the Longtan Formation.The principal mudstone constituents in different strata also differ,with carbonaceous mudstone,calcareous mudstone,iron mudstone,etc.being the most common.Low homogeneity,a significant degree of fragmentation,and poor cohesion define the mudstone in coal measurements.The X-ray diffraction test reveals that each mudstone specimen’s composition.There are at least three different types of minerals and a maximum of six different types.Chlorite,which is found in all high-content mudstone specimens,is discovered to be the most widely dispersed mineral.The SEM was used to precisely examine the microscopic morphology of mudstone specimens.It was discovered that the mineral components in mudstone rocks were distributed unevenly.The predominant mineral was chlorite,and other minerals were dispersed in it.Strong heterogeneity in the distribution of different minerals is the primary cause of the mudstone rock’s low mechanical strength.（2）Uniaxial compression deformation tests were created at various loading rates（DSLR,0.1,0.5,2.0,and 5.0 k N/s）to explore the correlation between the dilatancy and the loading rate.The significance of the differences between each group of data was examined using the single-factor ANOVA approach.The results indicate that the stress loading rate(V_load)is related to the uniaxial compressive strength（σ_c）,elastic modulus（E）,maximum axial strain(ε_a.max),maximum radial strain(ε_d.max),the initial dilatancy strength（f^*）,and the ratio of the initial dilatancy strength to the maximum strength（f^*/σ_c）.Ten uniaxial compression tests of rock with varying height-diameter ratios（L/D,1.54-2.29）were designed to explore the influence of L/D on rock strength parameters and deformation characteristics such as dilatation during uniaxial compression test.The results show that the test L/D is related toσ_c,E,ε_a.max,ε_d.max,ε_v.max,f^*,and f^*/σ_c,but not toε_v.ps,ε_v,d,ε_v,d/ε_v,max.The bigger the L/D,the stronger f^*,and the greater f^*/σ_c,that is,the smaller the specimen’s L/D,the easier it is to enter the volume dilatancy state.The triaxial compression experiments were designed under six different loading confining pressures（σ₃）.Predeterminedσ₃were 5,10,15,20,25,and 30MPa.The results show thatσ₃of a conventional triaxial test is related toσ_c,E,ε_a.ds,σ_rs,σ_ds,f^*,θ_d,and I_d,but not toε_d.dsandγ.The volume strain value of the specimen goes from positive to negative after entering the residual deformation stage,indicating that it has entered the dilatancy condition.The dilatancy will continue until the specimen is damaged.The greaterσ₃,the greater f^*,and the greater f^*/σ_ds,that is,the smallerσ₃,the smallerσ₃limit effect,and the easier it is to enter the dilatation stage.（3）The coupling stress model of the roadway stress field and coal seam extraction stress field is constructed.It is believed that a small modification in the stress field won’t result in the support failing or the roadway deforming significantly.The strength of the surrounding rock is lower than the static load condition in the case of repetitive disturbance or loading and unloading.The surrounding rock’s decreased mechanical strength as a result of frequent disturbance is the cause of the research object’s significant deformation,which results in the change from elastic-plastic to loose deformation.（4）The dilatancy boundary equation of the roadway with two-way uneven pressure is derived and established.The dilatancy boundary can be determined using the equation under the specified geostress level,lateral pressure coefficient,roadway radius,compressive strength,tensile strength,and internal friction angle.In-depth analysis is done on the effects of the lateral pressure coefficient,geostress level,highway radius,and other parameters on the dilatancy boundary.The dilatancy depth of the two sides,the roof and floor of the roadway,and the area of the dilatancy area are thought to initially reduce and then increase with the lateral pressure coefficient when it is between[0.25,1.75].The mechanical model of the surrounding rock pressure of the"arch highway"is built using Protodyakonov’s pressure arch theory.（5）Five key points for controlling the surrounding rock mass of mudstone roadway are put forward.Based on the engineering background of the repair project of the centralized haulage roadway in the+550m section of Wanshun coal mine in Guizhou province,and the cable support depth is determined by the dilatancy boundary equation,and the roadway repair plan is proposed on this basis.The field monitoring data shown that the scheme can significantly inhibit the large deformation trend of the surrounding rock of the roadway.