Experimental Study On Grouting Reinforcement And Bolting-grouting Support Of Broken Rock Mass Based On Alkali-activated Materials

In this paper,the performance research test of alkali-activated slag grouting material was carried out for the problem of grouting reinforcement and support of broken rock mass.As well as based on the alkali-activated slag grouting material,grouting reinforcement and combined anchor and grouting support tests of broken rock mass have been carried out.The effects of different factors on the performance of alkali-excited slag grouting materials and the change laws were determined.The physical properties of the grouted body under different grouting conditions,the mechanical properties,acoustic emission characteristics,and internal crack evolution laws under uniaxial loading were investigated.The mechanism of the action of single grouting reinforcement means and combined anchor and grouting support is also compared and analyzed.The following main conclusions are as follows:(1)The effects of different factors on the performance of alkali-excited slag grouting materials and the variation pattern are investigated based on orthogonal tests.The results show that changing the slag substitution rate has a significant effect on the grout’s flow rate,and the grout’s flow rate increases significantly and then decreases slightly with the increase of the slag substitution rate.Changing the alkali concentration of the grout significantly affects the initial and final setting time of the grout,and the grout’s initial and final setting time decreases significantly with the increase of the alkali concentration.Changing the alkali concentration significantly affects the compressive strength of the grouting material;with the increase of the alkali concentration of the grouting fluid,the compressive strength of the grouting material first decreases significantly then decreases slowly.The optimal ratio of grouting materials is obtained through comprehensive balance analysis: slag replacement rate of 50%,water glass modulus of 1.5,and alkali concentration of 1%.(2)Using the particle size of broken rock mass and grouting pressure as variables,grouting reinforcement tests on broken rock mass are carried out to investigate the physical properties of the grouted solids prepared under different conditions.The study shows that under the same conditions,when the particle size of the broken rock is 5-30 mm,with an increase of the particle size of the broken rock,the void ratio of the simulated stratum tends to increase gradually,the number of pores on the surface of the grouted body specimen keeps decreasing,the pore size decreases,the porosity tends to decrease gradually,and the longitudinal wave velocity of the grouted body specimen increases significantly.Under the same conditions,with the increase of grouting pressure,the number of pores on the surface of the grouted body decreases continuously,its pore size decreases,the longitudinal wave velocity of the grouted body specimen shows a trend of gradually increasing,the porosity all gradually decreases,the size of the largest pore inside the grouted body shrinks,but the degree of the grouting pressure reaches a certain value on the grouting governance enhancement is weakening.(3)Uniaxial compression tests are conducted on grout bodies formed by different grouting pressures and broken rock grain sizes.At the same time,acoustic emission(AE)technology is used to monitor the grout body specimens during the loading process,and loading simulation analysis is performed on the grout bodies based on PFC software.It is found that the uniaxial compressive strength of the grouted body gradually increases with the increase of grouting pressure under the same conditions.The peak AE ring count also increases continuously,and the area where the damaged cracks of the grouted body mainly appear changes from the rock-grout cementation interface to two areas of rock-grout cementation interface and grouting material cementation.Under the same conditions,the uniaxial compressive strength of the grouted body increases as the particle size of the broken rock increases,the peak AE ring count of the grouted body increases,and the width of the damaged crack of the grouted body specimen increases,while the curvature of its main crack path and the penetration area also increase significantly.Based on the acoustic emission parameter RAAF analysis,it is found that various types of grouted bodies are mainly damaged by shear cracking during destabilization.Based on the PFC numerical simulation software,the crack evolution of the grouted body during uniaxial loading was analyzed,and the results confirmed that both the crack initiation point and the crack propagation path of the grouted body specimen were mainly at the cementation interface between the grouted material and the broken rock mass.(4)Anchor rod and grouting co-support tests are carried out for grouting conditions with a grouting pressure of 0.3 MPa and a broken rock size of 5-10 mm.The results show that under the same grouting conditions,the anchor-injected body’s elasticity modulus and compressive strength are significantly greater than those of the anchorless grouted body.The axial and transverse peak strain of the anchor injected body are smaller than the corresponding peak strain of the anchorless grouted body.Its residual strength is greater than the residual strength of the anchorless grouted body.At the peak stress,the elastic strain energy of the anchor injected body is higher than that of the anchorless grouted body,and its dissipative strain energy is lower than that of the anchorless grouted body.Under the same conditions,the anchor injection body has a greater capacity to save energy and load-bearing capacity.