Experiment On Electrochemical Modification Of Mudstone

Mudstone is one of the main constituent rocks in the sedimentary rocks of coal measures strata.Its main mineral components are clay minerals,clastic minerals and so on.The relative content of clay minerals is up to 40%-90%.Because clay minerals have hydrological properties such as swelling,softening and weathering,under special hydrogeological conditions,the strength of surrounding rock is easy to decrease dramatically,resulting in instability of surrounding rock.Especially in the excavation of roadway and working face,the stress concentration of surrounding rock,the development of cracks,the weak mudstone under the action of stress field,hydrochemical and PHysical field,the roof and floor composed of mudstone are usually shown as muddy crushing,roof subsidence,floor floor floor heave and other rock pressure PHenomena.Because the interaction between mudstone and water has a certain time effect,the effect is slow and lasting.If the corresponding measures are not taken in time,safety accidents will easily occur,threatening people’s lives and causing economic losses.Therefore,the mudstone of No.2 coal floor in Wadong Coal Mine,Longkou City,Shandong Province is selected for the test,and the mudstone iselectrochemically modified by the self-developed percolation soft rock electrochemical modification test device.The effects of electrolyte concentration and DC electric field on the PHysical and chemical properties of mudstone,such as free swelling,water absorption,resistivity and mechanical strength,were studied by experiments.The effects of electrolyte concentration and DC electric field on the PHysical and chemical properties of mudstone were further revealed by studying its mineral composition and micro-morPHology characteristics.(1)The Brazilian splitting test results show that the uniaxial tensile strength of the modified mudstone is 10.55%~45% lower than that of the original control group.It can be concluded that the mudstone in the electrochemical modification is not only strengthened by electrochemical consolidation,but also weakened by hydrochemical corrosion.(2)The resistivity test results of each test group show that the resistivity of mudstone increases by 17.4%~80.61% after modification,and it is found that the resistivity of mudstone can reflect its strength,thus providing a simple method for strength test in geotechnical engineering.(3)The variation of mudstone temperature and test current in each test group shows that the concentration of electrolyte has an effect on the temperature and test current of mudstone in electrochemical modification test,and this effect is aggravated with the increase of electrolyte concentration.(4)The calculation results of water absorption and swelling rate ofmudstone in each test group show that increasing the concentration of electrolyte can inhibit water absorption and swelling of mudstone to a certain extent,and the uniaxial tensile strength of mudstone is negatively correlated with water absorption and swelling rate.(5)XRD diffraction results of mudstones of each test group show that with the increase of electrolyte concentration,the relative content of quartz in mudstone increases,and the uniaxial tensile strength of mudstone increases accordingly.Therefore,the strength of mudstone can be judged by the relative content of quartz in mudstone.(6)The results of scanning electron microscopy and energy spectrum analysis show that after the electrochemical modification test,the surface of mudstone mineral particles has been corroded and damaged to varying degrees,and the macroscopic manifestation is that the strength of mudstone decreases.