| The development of crack reinforcement and anchorage grouting technology in soil sites is gradually becoming systematic,especially in the exploration of grouting material modification has made great progress.The engineering practice shows that the grouting can effectively deal with the fracture disease of soil sites,and the grouting material has an important effect on the performance of the anchorage system.The existing grouting materials based on glutinous rice pulp and sintered stone powder have limited tensile and ductile properties,but there is still room for improvement in compressive properties.The fiber stiffening method can effectively solve the above problems.In this study,glutinous rice pulp,sintered stone powder and loess were used as the main mixing materials to explore the influence rule of mixing short-cut coconut husk fiber and basalt fiber on the properties of pulp.Two factors of mixing amount and length of two kinds of fiber were selected respectively,and 25 groups of samples were designed according to different levels by orthogonal test.The effects of natural fibers on the fluidity,shrinkage,unconfined compressive strength(UCS)and three-point flexural strength of grouting materials were studied,and the optimal mixing ratio of two kinds of fibers was analyzed by comprehensive balance method and combination optimization method,and the engineering application suggestions were simply given.The main conclusions are as follows:(1)Through the flow test,the analysis of fiber reinforced grouting materials with different dosage and length found that,with the increase of coir fiber length and content,the fluidity of reinforced grouting material decreases linearly,and the fluidity of basalt fiber reinforced grouting material also shows a similar rule.However,when the fiberlength and content are high,the fiber is easy to agglomerate to form barrier boundary and reduce the fluidity.(2)By measuring the shrinkage rate of 40mm×40mm×160mm stone body with the length comparator,it was found that shrinkage rate of stone body at 28 days decreased gradually with the increase of coir fiber content,and the shrinkage rate of sample was about 1.4%～2.2%,which met the requirement of 3% in the specification.The shrinkage rate of stone body decreases significantly with the increase of basalt fiber content,and the shrinkage rate of 6mm basalt fiber reinforced grouting material decreases by more than 40%.The cracks of the stone body increase with the increase of the dosage and length.Under the same dosage and length,the cracks of the basalt fiber are less than those of the coir fiber reinforced sample.(3)Under different lengths and contents of fiber reinforcement,UCS test of70.7mm×70.7mm×70.7mm sample and three-point bending strength test of 40mm×40mm× 160 mm sample were analyzed.The fiber length and dosage have the optimal value for the improvement of compressive strength(UCS)and flexural strength of grouting materials.By comprehensive balance analysis,it is suggested that the content of coconut shell fiber is 0.6% and the length is 6mm.The compressive strength and flexural strength of the corresponding samples are increased by 49.09% and 32.08%,respectively,compared with the control group.It is suggested that the basalt fiber content is 0.2% and the length is 6mm,and the compressive strength and flexural strength of the corresponding samples are 77.27% and 62.26% higher than that of the control group,respectively.Through combination optimization analysis,the optimal length of coir fiber is 8.5455 mm,the optimal content is 0.59%,the optimal length of basalt fiber is 9.0909 mm,the optimal content is 0.80%.(4)With the increase of coir fiber and basalt fiber content,the mechanical properties and toughness are significantly improved,and the energy dissipation capacity is enhanced.However,when the length and content are too high,the performance of the sample is affected.When the content of basalt fiber is more than 0.2%,the failure mode shows significant ductility.After fiber reinforcement,the soil is braided into a three-dimensional network structure.The fibers in different positions and directions squeeze the matrix after being stressed,which effectively limits the deformation and slip of matrix particles and improves the macroscopic mechanical properties. |
