Preparation Of Carbon Nanotube Cement-based Grouting Material And Study On Mechanical Properties Of Rock Fracture Surface

Carbon nanotube modified cement-based composite has a good application prospect in the field of fracture rock reinforcement,but the relevant research is less.Due to the agglomeration of nano particles,the mechanical properties of carbon nanotube cement composite can not be fully guaranteed.Therefore,it is necessary to develop a new dispersion method to improve the dispersion stability of carbon nanotubes,to prepare carbon nanotubes cement grouting materials with stable performance,and to carry out research on carbon nanotubes cement-based materials in the field of rock grouting reinforcement.In this paper,based on the existing research results,the preparation method of cement-based grouting material reinforced by carbon nanotubes is further expanded.Study on the application method and dispersion mechanism of cement grouting material with single wall carbon nanotubes stabilized and dispersed by fulvic acid for the first time.The effect of single wall carbon nanotube cement grouting material on the mechanical properties of rock samples with fracture surface is analyzed.The influence of grouting material,angle of fracture surface,roughness of fracture surface and quantity of fracture surface on the mechanical strengthening characteristics and fracture law of fracture surface of grouting rock sample is studied.The main research results and conclusions are as follows:(1)The dispersion stability of SWNTs containing 0.12wt% fulvic acid is the best.At this concentration,fulvic acid can be adsorbed on the surface of SWNTs and increase the ? potential of SWNTs.So as to reduce the agglomeration of carbon nanotubes in alkaline aqueous solution and realize long-term stable dispersion.The appropriate concentration of fulvic acid(0.05wt%-0.10wt%)in cement grouting material is beneficial to the dispersion of SWNTs in alkaline solution and can enhance the mechanical properties of cement paste.The compressive strength and tensile strength can be increased by 31.9% and 47.9% respectively.Cohesion and internal friction angle increased by 12% and 21%,respectively.(2)For the white sandstone samples with different dip angle fracture surface,the mechanical properties of fracture surface enhanced by single-walled carbon nanotube cement grouting materials are obvious.It can effectively improve the integrity and strength of the flat fracture samples with different dip angles,and the maximum increase of the peak compressive strength of the samples is 147.8%.For the white sandstone samples with different dip angle and rough fracture surface,when the mechanical strength of fracture surface is easy to deteriorate from 45° to 75°,the mechanical strengthening effect is the most obvious,with a maximum increase of 204%.SWCNTs cement grouting material greatly reduces the influence of the increase of the inclination angle of the fracture surface on the strength deterioration of the sample.(3)For the white sandstone samples with different roughness fracture surface,the single-walled carbon nanotube cement grouting material can enhance the mechanical properties and deformation resistance of the fracture surface rock mass with various JRC values,which is universal.Compared with the control group,the dispersion of peak stress value and peak strain value of each JRC value in the experimental group is lower.When the JRC value of fracture surface is 6,the peak strength and modulus of elasticity of experimental group increase by 142.33% and 146% respectively.(4)The peak strength and peak strain of the numerical sample show a "V" shape change trend with the increase of the fracture surface angle ?.The peak strain reaches the minimum value when the dip angle is 75° and the peak strength reaches the minimum value when the dip angle is 60°.When the angle of fracture ? is 0°,60° and 90°,it is the best match with the indoor physical sample.The number of shear cracks decreases first and then increases with the increase of dip angle ?,which is similar to the change of strength deformation characteristics.The peak strength and strain of the numerical specimen increase with the increase of JRC value.The strength and the deformation resistance of the specimen are deteriorating with the increase of the number of the pre cracked surfaces.When the JRC value is 20,the degradation of mechanical strength is the most obvious and the sensitivity is the highest.