Study On The Effect Of Fiber On Rootzone Mechanical Action Mechanism And Turf Quality For Football Field

Adoption of sand-based rootzone has become a common understanding in building high quality football fields in the domestic and overseas.Because of the poor stability of sand,the mechanical properties of rootzone are insufficient,so it is difficult to meet the needs of high-intensity matches.Fiber reinforced rootzone is an effective construction method to improve the stability of the sand-based rootzone in the football field.However,the fiber reinforced mechanism on the rootzone and the effect of different fibers on the strength of rootzone are still lacking.Meanwhile,the effects of different fibers and their aging compounds on turfgrass,soil bacteria and their effects on the playing quality are still unclear.In this study,the rootzone treated with PET fiber,coir fiber and carbon fiber and mixed with the ratio of fiber to sand dry weight(W/W)of 0.4% was taken as the research object.The mechanical characteristics of roots and three kinds of fibers are analyzed by means of geotechnical test and model simulation in this study,and the strength and reinforced mechanism of the three kinds of fibers on the sand-based rootzone were studied,and the prediction effect of the model calculation fiber on reinforcement of rootzone is also studied.At the same time,the effects of three kinds of fibers and their aging compounds on turfgrass,soil bacteria and the playing quality of the fiber reinforced rootzone is studied.The main conclusions are as follows:(1)Compared with CK,PET fiber can significantly improve the porosity and saturated water conductivity of sand-based rootzone.The porosity and saturated water conductivity of coir fiber and carbon fiber is not significantly different from CK.The grass color and NDVI under CK and PET treatments decrease significantly with time,and the decrease trend is alleviated by the treatment of coir fiber and carbon fiber.The aboveground biomass of carbon fiber treatment increase significantly.The total root length and the number of root tips of turfgrass treated with PET and carbon fiber increase significantly.The underground biomass of coir fiber treatment is significantly higher than that of other treatments.Among all treatments,the root cross-sectional area ratio(RAR)of diameter class between 0.2and 0.3mm is the highest.(2)The tensile strength and Young's modulus of carbon fiber are the highest,while those of PET are the lowest.The tensile strength and Young's modulus of coir fiber and grass roots are negatively correlated with diameter by power function regression.With the increase of time,the tensile strength and Young's modulus of the three kinds of fibers decrease gradually,and the decrease trend of PET is the slowest.The fiber and grass root together constitute the shear strength enhancement region,which acts on the stability of rootzone.The peak strength,fiber containing(root)effect coefficient and additional cohesion of coir fiber are significantly higher than those of CK and other treatments,and the strengthening effect of coir fiber is better than that of carbon and PET fiber.There is no significant difference between carbon fiber treatment and CK,while PET treatment is lower than CK.Direct use of the WU model to predict the additional cohesion of "fiber-root-sand" composite soil will overestimate the strengthening effect of fiber and rootzone.According to the measured values of composite soil in different periods,the correction coefficient k ' model is established for the WU model.Therefore,the modified WU model can more accurately predict the strengthening effects of the three fibers on the sand-based rootzone in different periods.(3)In this study,it is found that the carboxyl group--COOH,--CH2--CH2--and C--C--C are the main functional groups of PET aging liquid.Coir fiber aging liquid mainly contains pyran ring functional groups,aromatic ring skeleton functional groups,cellulose and hemicellulose functional groups,and glycosidic bond functional groups.C-C-C and amine-C-N functional groups are the main components of carbon fiber aging liquid.After applying the aging liquid,there is no significant difference in the observed quality of the turf.PET aging liquid can destroy the membrane permeability of turfgrass leaves,and cause hydrogen peroxide and superoxide stress on the leaves.Both carbon fiber aging liquid and coir fiber aging liquid induced peroxidation stress on leaves,but coir fiber aging liquid can significantly alleviate the decreasing trend of chlorophyll.Compared with CK,PET aging liquid significantly increased soil p H,increased the activities of NAG,LAP,AP and the number of bacterial communities,and inhibited the activities of CB and catalase.Coir fiber aging liquid slow down the rising trend of soil p H,increase the activities of CB and NAG and the number of fungi and bacteria communities,and inhibit the activities of LAP and catalase.Carbon fiber aging liquid significantly decrease soil p H,increase the number of soils actinomycetes community,but inhibited the activities of N and P circulate and catalase.(4)Under the traffic condition,the PET treatment turf can significantly alleviate the traffic damage to turfgrass,and the head injury risk(HIC)is the lowest,but the turf bed performance and playing performance are lower than those of CK and other treatments.There was no significant difference between the carbon fiber treatment turf and CK in alleviating the traffic damage to turfgrass,turf bed performance and playing performance.Coir fiber turf can also alleviate the traffic damage to turfgrass,although its HIC is higher than other treatments,but its turf bed performance and playing performance are significantly higher than other treatments.