The current study aims to evaluate the dynamic response of stabilized cohesive soil using an enzymatic preparation in terms of resilient modulus.We ran a series of resilient modulus testing according to AASHTO T307 on...The current study aims to evaluate the dynamic response of stabilized cohesive soil using an enzymatic preparation in terms of resilient modulus.We ran a series of resilient modulus testing according to AASHTO T307 on three types of cohesive soil treated with an enzymatic preparation to investigate its potential on roads construction.The results show significant improvement in the resilient modulus values,estimated at 1.4 to 4.4 times that observed for the untreated soil.Because of the complexity in conducting the resilient modulus measurement,we did a regression analysis to produce reliable correlation formula to predict the resilient modulus for untreated and stabilised soil samples involving stress state.The resilient modulus values for the subgrade materials at the anticipated field stresses were determined using a universal model.The enzymatic preparation was applied in pavement of a sample road and evaluated using the plate load test.SEM analysis for soil samples shows improvement in the soil compaction via reduction of voids between soil particles.XRD analysis shows no major structural changes in the treated soils.The enzymatic preparation contains 43 mg/mL of proteins.We used the SDS-PAGE(sodium dodecyl sulphate polyacrylamide gel electrophoresis)technique to identify the main protein components;however,the presence of interfering materials(surfactants)hinders the separation.展开更多
The modulus of soil reaction,representing the stiffness of a soil surrounding pipes,is a critical parameter in the design of buried flexible pipes.This study conducted plate loading tests on corrugated polyvinyl chlor...The modulus of soil reaction,representing the stiffness of a soil surrounding pipes,is a critical parameter in the design of buried flexible pipes.This study conducted plate loading tests on corrugated polyvinyl chloride,smooth polyvinyl chloride,and high-density polyethylene pipes buried in lightweight cellular concrete(LCC)backfills at densities of 400,475,550,and 650 kg/m^(3)to investigate the pipe deformation behavior and moduli of soil reaction.In addition,this study examined the effects of the narrow trench condition on the pipe deformation and modulus of soil reaction.In these tests,the vertical and horizontal diameter changes of pipes under the vertical pressures applied through a hydraulic jack were measured.Test results reveal that the average moduli of soil reaction of plastic pipes within a wide trench backfilled by the LCCs at densities of 400,475,550,and 650 kg/m^(3)were back-calculated as 66,99,133,and 205 MPa,respectively,using the modified Iowa formula.Furthermore,the back-calculated moduli of soil reaction for LCCs exhibited linear relationships with their densities and unconfined compressive strengths and were higher than the recommended values for the commonly used soil backfills.Based on the vertical deformation criterion of 5%pipe diameter,the ultimate bearing capacities of flexible pipes buried in wide LCCs at densities of 475,550,and 650 kg/m^(3)exceeded 500 kPa.The LCC with a narrow trench exhibited a lower modulus of soil reaction and ultimate bearing capacity but a larger pipe diameter change.展开更多
基金Project supported by the Academy of Scientific Research and Technology,ASRT,Cairo,Egypt
文摘The current study aims to evaluate the dynamic response of stabilized cohesive soil using an enzymatic preparation in terms of resilient modulus.We ran a series of resilient modulus testing according to AASHTO T307 on three types of cohesive soil treated with an enzymatic preparation to investigate its potential on roads construction.The results show significant improvement in the resilient modulus values,estimated at 1.4 to 4.4 times that observed for the untreated soil.Because of the complexity in conducting the resilient modulus measurement,we did a regression analysis to produce reliable correlation formula to predict the resilient modulus for untreated and stabilised soil samples involving stress state.The resilient modulus values for the subgrade materials at the anticipated field stresses were determined using a universal model.The enzymatic preparation was applied in pavement of a sample road and evaluated using the plate load test.SEM analysis for soil samples shows improvement in the soil compaction via reduction of voids between soil particles.XRD analysis shows no major structural changes in the treated soils.The enzymatic preparation contains 43 mg/mL of proteins.We used the SDS-PAGE(sodium dodecyl sulphate polyacrylamide gel electrophoresis)technique to identify the main protein components;however,the presence of interfering materials(surfactants)hinders the separation.
基金supported by the CEMATRIX Corp.The authors would like to thank technicians David Woody,Kent Dye,and Meyer Carey in the Civil,Environmental,&Architectural Engineering Department at the University of Kansas,for their great assistance in modifying and calibrating the test devices used in this studyThe authors also would like to appreciate Ph.D.student Alsharari Turki from the University of Kansas and formerly visiting student Hsin-Ming Wu at the University of Kansas,and Albert Fang from CEMATRIX for their great help on the model tests.Josh Beakley at the American Concrete Pipe Association provided valuable comments and suggestions for the data analysis of soil reaction modulus.
文摘The modulus of soil reaction,representing the stiffness of a soil surrounding pipes,is a critical parameter in the design of buried flexible pipes.This study conducted plate loading tests on corrugated polyvinyl chloride,smooth polyvinyl chloride,and high-density polyethylene pipes buried in lightweight cellular concrete(LCC)backfills at densities of 400,475,550,and 650 kg/m^(3)to investigate the pipe deformation behavior and moduli of soil reaction.In addition,this study examined the effects of the narrow trench condition on the pipe deformation and modulus of soil reaction.In these tests,the vertical and horizontal diameter changes of pipes under the vertical pressures applied through a hydraulic jack were measured.Test results reveal that the average moduli of soil reaction of plastic pipes within a wide trench backfilled by the LCCs at densities of 400,475,550,and 650 kg/m^(3)were back-calculated as 66,99,133,and 205 MPa,respectively,using the modified Iowa formula.Furthermore,the back-calculated moduli of soil reaction for LCCs exhibited linear relationships with their densities and unconfined compressive strengths and were higher than the recommended values for the commonly used soil backfills.Based on the vertical deformation criterion of 5%pipe diameter,the ultimate bearing capacities of flexible pipes buried in wide LCCs at densities of 475,550,and 650 kg/m^(3)exceeded 500 kPa.The LCC with a narrow trench exhibited a lower modulus of soil reaction and ultimate bearing capacity but a larger pipe diameter change.
