Effect of different binder and fiber combinations on shear resistance of substrate and plant growth of spray seeding
[Objective]To investigate the effect of adding"binder + plant fiber"on the shear performance and plant growth of the substrate during the early stages of guest soil spraying,and to provide reference for engineering practice.[Method]The ring knife method,direct shear method and simulated slope method were employed.Two binders,Polyacrylic amide(PAM)and Polyvinyl alcohol(PVA),and four plant fibers,palm fiber(PF),coconut fi-ber(CF),sisal fiber(SF)and wood fiber(WF),were selected.The porosity,shear resistance and vegetation growth characteristics of sprayed substrates were investigated under the two combinations of binder and fiber.[Result]The results showed that(1)PAM+SF exhibited the highest porosity,with total and capillary porosity significantly higher than CK(P<0.05),at 1.26 and 1.37 times higher than those of CK,respectively;(2)Addition of PAM enhanced the shear strength of the fiber-soil composite,with internal friction angles of PAM+CF and PAM+SF significantly higher than those of CK and other treatment groups(P<0.05),at 1.71 and 1.88 times higher than those of CK,re-spectively,while the cohesion of PAM+PF combination was significantly higher than that of CK(P<0.05),at 1.14 times higher than that of CK;(3)PVA+SF combination showed the best plant growth condition,with total biomass to root crown ratio significantly greater than CK(P<0.05).[Conclusion]Combining with PAM can im-prove the shear resistance of the sprayed substrate;PAM exhibited better shear strength compared to PVA.Shear re-sistance of sprayed substrates was influenced by both binder and plant fiber.The"binder + plant fiber"combination promotes vegetation growth recovery.
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