Study On The Degradation Of Mechanical Parameters Of Lanping Lead-zinc Deposit Under The Action Of Dry-wet Cycles

Due to some mine slope rock mass in the rain prone to soften and disintegration,rainfall and evaporation cycle effect,the degree of rock mass under the effect of the cyclic degradation than rock have been bubble in water is more serious,because of the degradation effect,the rock mechanics parameters of rock mass in mines is changes with the influence of the outside world.This damage is gradually accumulated,although the effect of a single time is not obvious,but the accumulation of a long time will also reach a large accumulation of damage,the accumulation of such damage to a certain number of rock and soil will reach the critical state of the mine slope rock and soil,rock and soil failure.Therefore,it is necessary to study the degradation of rock mechanical parameters under the action of dry and wet cycles.Normally we can uniaxial compressive strength are back at the scene,and then processed into standard specimen,and again in the indoor uniaxial experiment,carried out on the rock mass quality evaluation can be RMR values,with this value can use hawk-brown's strength criterion,this criteria can be put to correct the reduction,the rock mechanics parameters,mechanical parameters can get a rough,and because of long time needed for shear test,the high cost,so the dry-wet circulation function degradation study of rock mechanics parameters,only need to select representative of uniaxial compressive strength.The institute's need of sample is in yunnan province take the open stope orchid jinding lead-zinc deposit,take back the sample will be processed into standard sample,while do dry-wet cycle test,can measure the bibulous rate of different stages of specimen,in order to observe the dry-wet circulation after the mechanical properties of specimens of deformation,failure and will need to do uniaxial compressive test,the corresponding diagram is obtained by the data sorting.The uniaxial compressive strength measured by experiment was analyzed by PFC~2DD numerical simulation software.Finally,the damage mechanism of the samples under the action of dry and wet circulation is comprehensively analyzed,which provides certain reference significance and reference value for the future study on the slope stability of the mine.The main content of this paper is as follows:(1)the material composition,particle size and cementation type of the selected sample were determined,laying a foundation for the study of the damage mechanism of the sample under the action of dry and wet circulation.The rock sample was cut into thin slices and sent to be analyzed.It was known that the sample was grey quartz fine sandstone.The main components of quartz sandstone were sand-like clastics and interstitials,etc.The particle size was between 0.06-0.3mm.Sand clastic grinding round medium-poor,shape is sub-round-angular shape;Sorting medium,grain size in the fine sand range,very few in the middle sand range.The interstitial materials are calcite,sphalerite and pyrite,and the distribution of the three is uneven,showing pore-basement cementation.Finally,a small amount of tourmaline and zircon are scattered in the samples.(2)uniaxial compressive strength,water absorption rate and deformation and failure characteristics of samples after dry and wet cycling were obtained by uniaxial compression test in laboratory,and the relationship between them and the number of dry and wet cycling was summarized.(3)according to the mechanical parameters obtained from laboratory tests,a PFC~2DD numerical model was established to analyze the microscopic changes of the model,and the relationship between the number of dry and wet cycles and the microscopic parameters was analyzed and summarized.(4)according to the results of sem,the damage mechanism of the samples under the action of dry and wet circulation was analyzed and summarized,and the prevention measures were proposed.