Study On Variation Characteristics Of Apparent Resistivity Of Mining Rock Mass Under The Action Of Seepage

Affected by the disturbance of coal mining,the rock mass whose stability is reduced is called mining rock mass.With the increase of the frequency of heavy rainfall in recent years,the deformation of mining rock mass caused by rainfall is aggravated,and the problems of slope slide and collapse are becoming more and more prominent,which seriously affect the safety of mining area production and people's life and property.Based on this,this paper selected three typical mining slope samples in guizhou province under different mining conditions:undeveloped slope,near-mining slope and long-mining slope as the classification index.On the basis of detailed geological survey,the variation characteristic data of apparent resistivity profile of sample slope before and after rainfall were collected.Three types of slope test models were constructed,and physical simulation experiments were carried out.By controlling the mining conditions,the stress-strain condition and the variation law of apparent resistivity of the model slope under cyclic rainfall conditions were studied,and the variation characteristics of apparent resistivity of mining rock mass under the action of rainfall and seepage were explored.The physical calculation model of constant head is established to calculate the permeability coefficient and the permeability coefficient change rate of the experimental model.The results can be used to preliminarily identify the characteristics of internal fracture development,delineate the influence boundary of goaf,predict the potential sliding surface of mining landslide,and determine the stability of rock mass.It also provides reference and theoretical support for the prevention and control of mining slope geological hazards.In this paper,the field investigation and physical simulation test were used to study the variation characteristics of apparent resistivity under the seepage action of typical"steep and slow"mining slope in guizhou province.The following research results were mainly obtained:(1)Identified the morphological and structural characteristics of the slope,and the coefficient of similarity ratio was determined to be 1:800.The slope types of the research points were all in the form of"ascending steep descending slow".The upper steep area mainly exposed the lower Triassic jialing river formation and feixianguan formation,while the lower gentle area mainly exposed the upper Permian longtan formation.(2)Estimated the seepage coefficient of the three models'seepage channels and the average rate of change of the permeability coefficient of the mining slope.Using the equivalence principle,the physical calculation model of constant water head was constructed,and the permeability coefficients of the models of long-mining,near-mining and non-mining slopes were calculated:k _long-mining=7.63×10-3cm/s,k _near-mining=7.13×10-3cm/s,k _non-mining=6.26×10-3cm/s.The the near mining slope average rate of change in 4h isdk_near-mining=6.04×10^-8c m/s^-2,and that in the long mining slope in 24h isdk_long-mining=6.04×10^-8c m/s^-2.(3)Obtained the surface settlement deformation of the slope under the action of rainfall under different mining conditions.The surface deformation of the undeveloped slope is mainly manifested as scattered low-lying grooves and scour accumulation at the slope foot.The maximum settlement of the near-mining slope reached 11mm and the average settlement reached about 8mm.The maximum settlement of long-mining slope reached 16mm,and it was still in the creep stage with the continuous rainfall.(4)Found that the sudden change of apparent resistivity value in the slope profile of the mining rock mass under the action of seepage is closely related to the occurrence of compaction or abscission deformation in the rock mass.In the process of overburden deformation and failure,"temporary stress support zone"has been formed in the rock mass for many times,that is,the rock mass in the upper and lower stress zones has different settlement velocity,and the upper part is larger than the lower part,which is manifested as the support function.On the contrary,it is shown that the water content increases and the apparent resistivity decreases under the action of separation.(5)Verified that the main factors causing the change of apparent resistivity value of the undeveloped slope rock mass are gravity and topography,and the seepage channel is easy to form in the gully position.It is clear that the apparent resistivity of the fracture position in the mining slope varies greatly before and after rainfall.By comparing the change of apparent resistivity of rock mass before and after rainfall,the development of internal fractures can be preliminarily identified,the influence boundary of goaf can be delineated,the potential sliding surface of mining landslide can be predicted,and the stability of rock mass can be determined.