含水率变化下压实路基土动态回弹模量试验研究与预估模型
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摘要
路基土动态回弹模量MR是路面设计和使用性能评价采用的关键参数,运营期间受含水率变化影响显著。以压实红黏土为研究对象,制备了6个不同含水率和3种不同压实度的试样,采用滤纸法测试了不同状态下的基质吸力,并通过动三轴试验研究了含水率、压实度、动偏应力和围压对动态回弹模量的影响。试验结果表明:MR随压实度、围压的增大而增大,随动偏应力增大呈非线性减小;MR随含水率增大急剧降低,从最佳含水率增加4.5%时,不同压实度下MR均降低约50%,动偏应力和压实度对MR的影响随含水率增大逐渐减弱;MR随含水率和饱和度的变化规律与土性显著相关,而不同土样的MR随基质吸力变化趋势基本一致。进而引入基质吸力,建立了综合考虑含水率和应力水平影响的压实路基土MR预估模型,通过本文和文献试验数据证实了该模型的适用性,并基于13种土样的试验结果建立了模型参数与物性指标之间的经验关系。
The dynamic resilient modulus(MR) of subgrade soils is the key parameter used in pavement design and performance evaluation, and is significantly affected by variation of moisture content during operation. The compacted lateritic soil is used, and the test specimens are prepared using six different moisture contents and three degrees of compaction. The repeated loading triaxial tests are conducted to investigate the effects of moisture content, degree of compaction, dynamic deviator stress and confining pressure on dynamic resilient modulus, and the soil suctions of different specimens are measured using the contact filter paper method right after cyclic loading tests. The test results indicate that MR increases with the increasing confining pressure and degree of compaction, and decreases nonlinearly with the increasing dynamic deviator stress. The values of MRdecrease greatly with the increasing moisture content, as moisture content increases by 4.5% from the optimum moisture content, they decrease to about 50% of the initial values, and the influences of dynamic deviator stress and compactness on MRdecrease with the increasing moisture content. In addition, the relationships for both MR – moisture content and MR – degree of saturation are highly soil type-dependent, while the variation of MR with soil suction is similar for different soils. Thus by incorporating the soil suction into confining stress, a new prediction model for the resilient modulus taking into account both the stress state and the moisture content is proposed. The suitability of the proposed model is validated through the experimental data from this study and the existing literatures. Then the empirical relationships between model parameters and physical properties of soils are developed based on the statistical regression analysis performed on 13 different soils, and a good agreement between the measured and predicted values of MRobtained using the regression model parameters is found. This study may provide a simple and reliable method fordetermining the reasonable resilient modulus of compacted subgrade soils in pavement structure design.
The dynamic resilient modulus(MR) of subgrade soils is the key parameter used in pavement design and performance evaluation, and is significantly affected by variation of moisture content during operation. The compacted lateritic soil is used, and the test specimens are prepared using six different moisture contents and three degrees of compaction. The repeated loading triaxial tests are conducted to investigate the effects of moisture content, degree of compaction, dynamic deviator stress and confining pressure on dynamic resilient modulus, and the soil suctions of different specimens are measured using the contact filter paper method right after cyclic loading tests. The test results indicate that MR increases with the increasing confining pressure and degree of compaction, and decreases nonlinearly with the increasing dynamic deviator stress. The values of MRdecrease greatly with the increasing moisture content, as moisture content increases by 4.5% from the optimum moisture content, they decrease to about 50% of the initial values, and the influences of dynamic deviator stress and compactness on MRdecrease with the increasing moisture content. In addition, the relationships for both MR – moisture content and MR – degree of saturation are highly soil type-dependent, while the variation of MR with soil suction is similar for different soils. Thus by incorporating the soil suction into confining stress, a new prediction model for the resilient modulus taking into account both the stress state and the moisture content is proposed. The suitability of the proposed model is validated through the experimental data from this study and the existing literatures. Then the empirical relationships between model parameters and physical properties of soils are developed based on the statistical regression analysis performed on 13 different soils, and a good agreement between the measured and predicted values of MRobtained using the regression model parameters is found. This study may provide a simple and reliable method fordetermining the reasonable resilient modulus of compacted subgrade soils in pavement structure design.
引文
[1]SEED H B,CHAN C K,LEE C E.Resilience characteristics of subgrade soils and their relation to fatigue failures in asphalt pavements[C]//Proceedings of the International Conference on the Structural Design of Asphalt Pavements.Michigan,1962:611-636.
[2]National Cooperative Highway Research Program(NCHRP).Development of the 2002 guide for the design of new and rehabilitated pavement structures[R].Washington,D C:NCHRP Transportation Research Board,2004.
[3]JTG D50-2017公路沥青路面设计规范[S].2017.(JTG D50-2017 Specification for design of highway asphalt pavement[S].2017.(in Chinese))
[4]NGUYEN Q,FREDLUND D G,SAMARASEKERA L,et al.Seasonal pattern of matric suctions in highway subgrades[J].Canadian Geotechnical Journal,2010,47(3):267-280.
[5]钱劲松,王朋,凌建明,等.潮湿多雨地区高速公路路基湿度的实测特征[J].同济大学学报(自然科学版),2013,41(12):1812-1817.(QIAN Jin-song,WANG Peng,LINGJian-ming,et al.In-situ investigation of subgrade moisture of expressway in humid zone[J].Journal of Tongji University(Natural Science),2013,41(12):1812-1817.(in Chinese))
[6]DRUMM E C,REEVES J S,MADGETT M R,et al.Subgrade resilient modulus correction for saturation effects[J].Journal of Geotechnical and Geoenvironmental Engineering,1997,123(7):663-670.
[7]LIANG R Y,RABAB’AH S,KHASAWNEH M.Predicting moisture-dependent resilient modulus of cohesive soils using soil suction concept[J].Journal Transportation Engineering,2008,134(1):34-40.
[8]SALOUR F.Moisture influence on structural behaviour of pavements:field and laboratory investigations[D].Stockholm:KTH Royal Institute of Technology,2015.
[9]MEHROTRA A,ABU-FARSAKH M,GASPARD K.Development of subgrade Mr constitutive models based on physical soil properties[J].Road Materials and Pavement,2018,19(1):56-70.
[10]WITCZAK M W,UZAN J.The universal airport pavement design system.Report I of V:granular material characterization[R].Maryland:University of Maryland,1988.
[11]LEKARP F,ISACSSON U,DAWSON A.State of the art I:resilient response of unbound aggregates[J].Journal of Transportation Engineering,2000,126(1):66-75.
[12]LI D,SELIG E T.Resilient modulus for fine-grained subgrade soils[J].Journal of Geotechnical Engineering,1994,120(6):939-957.
[13]KHOURY N,BROOKS R,BOENI S Y,et al.Variation of resilient modulus,strength,and modulus of elasticity of stabilized soils with postcompaction moisture contents[J].Journal of Materials in Civil Engineering,2013,25(2):160-166.
[14]HEATH A C,PESTANA J M,HARVEY J T,et al.Normalizing behavior of unsaturated granular pavement materials[J].Journal of Geotechnical and Geoenvironmental Engineering,2004,130(9):896-904.
[15]NG C W W,ZHOU C,YUAN Q,et al.Resilient modulus of unsaturated subgrade soil:experimental and theoretical investigations[J].Canadian Geotechnical Journal,2013,50(2):223-232.
[16]FREDLUND D G,RAHARDJO H.Soil mechanics for unsaturated soils[M].New York:Wiley-Interscience,1993.
[17]YANG S R,LIN H D,KUNG J H,et al.Suction-controlled laboratory test on resilient modulus of unsaturated compacted subgrade soils[J].Journal of Geotechnical and Geoenvironmental Engineering,2008,134(9):1375-1384.
[18]KHOURY N,BROOKS R,KHOURY C,et al.Modeling resilientmodulus hysteretic behavior with moisture variation[J].International Journal of Geomechanics,2012,12(5):519-527.
[19]SALOUR F,ERLINGSSON S,ZAPATA C E.Modelling resilient modulus seasonal variation of silty sand subgrade soils with matric suction control[J].Canadian Geotechnical Journal,2014,51(12):1413-1422.
[20]HAN Z,VANAPALLI S K.Relationship between resilient modulus and suction for compacted subgrade soils[J].Engineering Geology,2016,211:85-97.
[21]ZAMAN M,SOLANKI P,EBRAHIMI A,et al.Neural network modeling of resilient modulus using routine rubgrade soil properties[J].International Journal of Geomechanics,2010,10(1):1-12.
[22]YAN K Z,XU H B,SHEN G H.Novel approach to resilient modulus using routine subgrade soil properties[J].International Journal of Geomechanics,2014,14(6):04014025.
[23]ZHOU C J,HUANG B S,DRUMM E,et al.Soil resilient modulus regressed from physical properties and influence of seasonal variation on asphalt pavement performance[J].Journal of Transportation Engineering,2015,141(1):04014069.
[24]AASHTO.Designation T307-99:determining the resilient modulus of soils and aggregate materials[S].Washington:American Association of State Highway and Transportation Officials,2003.
[25]ASTM Designation:D5298-10.Standard test method for measurement of soil potential(suction)using filter paper[S].West Conshohocken,PA:American Society for Testing and Materials,2010.
[26]LEONG E C,HE L,RAHARDJO H.Factors affecting the filter paper method for total and matric suction measurements[J].Geotechnical Testing,2002,25(3):322-333.
[27]FREDLUND D G,XING A.Equation for the soil-water characteristic curve[J].Canadian Geotechnical Journal,1994,31:521-532.
[28]JTG D30-2015公路路基设计规范[S].2015.(JTG D30-2015 Specification for design of highway subgrades[S].2015.(in Chinese))
[29]HAN Z,VANAPALLI S K,ZOU W L.Integrated approaches for predicting soil-water characteristic curve and resilient modulus of compacted fine-grained subgrade soils[J].Canadian Geotechnical Journal,2017,54(5):646-63.
[30]KHALILI N,KHABBAZ M H.A unique relationship for the determination of the shear strength of unsaturated soils[J].Géotechnique,1998,48(2):1-7.
[31]VANAPALLI S K,FREDLUND D G,PUFAHL D E,et al.Model for the prediction of shear Strength with respect to soil suction[J].Canadian Geotechnical Journal,1996,33(3):379-392.
[32]GARVEN E A,VANAPALLI S K.Evaluation of empirical procedures for predicting the shear strength of unsaturated soils[C]//ASCE.Proceedings of the 4th International Conference on unsaturated Soils.Carefree,2006:2570-2581.
[33]GUPTA S C,RANAIVOSON A,EDIL T B,et al.Pavement design using unsaturated soil technology[R].Minnesota:Minnesota Department of Transportation,St.Paul,2007.
[34]兰伟.路基土非饱和特性及回弹模量预估模型[D].上海:同济大学,2009.(LAN Wei.Unsaturated characteristics and prediction model of and resilient modulus of subgrade soil[D].Shanghai:Tongji University,2009.(in Chinese))
[2]National Cooperative Highway Research Program(NCHRP).Development of the 2002 guide for the design of new and rehabilitated pavement structures[R].Washington,D C:NCHRP Transportation Research Board,2004.
[3]JTG D50-2017公路沥青路面设计规范[S].2017.(JTG D50-2017 Specification for design of highway asphalt pavement[S].2017.(in Chinese))
[4]NGUYEN Q,FREDLUND D G,SAMARASEKERA L,et al.Seasonal pattern of matric suctions in highway subgrades[J].Canadian Geotechnical Journal,2010,47(3):267-280.
[5]钱劲松,王朋,凌建明,等.潮湿多雨地区高速公路路基湿度的实测特征[J].同济大学学报(自然科学版),2013,41(12):1812-1817.(QIAN Jin-song,WANG Peng,LINGJian-ming,et al.In-situ investigation of subgrade moisture of expressway in humid zone[J].Journal of Tongji University(Natural Science),2013,41(12):1812-1817.(in Chinese))
[6]DRUMM E C,REEVES J S,MADGETT M R,et al.Subgrade resilient modulus correction for saturation effects[J].Journal of Geotechnical and Geoenvironmental Engineering,1997,123(7):663-670.
[7]LIANG R Y,RABAB’AH S,KHASAWNEH M.Predicting moisture-dependent resilient modulus of cohesive soils using soil suction concept[J].Journal Transportation Engineering,2008,134(1):34-40.
[8]SALOUR F.Moisture influence on structural behaviour of pavements:field and laboratory investigations[D].Stockholm:KTH Royal Institute of Technology,2015.
[9]MEHROTRA A,ABU-FARSAKH M,GASPARD K.Development of subgrade Mr constitutive models based on physical soil properties[J].Road Materials and Pavement,2018,19(1):56-70.
[10]WITCZAK M W,UZAN J.The universal airport pavement design system.Report I of V:granular material characterization[R].Maryland:University of Maryland,1988.
[11]LEKARP F,ISACSSON U,DAWSON A.State of the art I:resilient response of unbound aggregates[J].Journal of Transportation Engineering,2000,126(1):66-75.
[12]LI D,SELIG E T.Resilient modulus for fine-grained subgrade soils[J].Journal of Geotechnical Engineering,1994,120(6):939-957.
[13]KHOURY N,BROOKS R,BOENI S Y,et al.Variation of resilient modulus,strength,and modulus of elasticity of stabilized soils with postcompaction moisture contents[J].Journal of Materials in Civil Engineering,2013,25(2):160-166.
[14]HEATH A C,PESTANA J M,HARVEY J T,et al.Normalizing behavior of unsaturated granular pavement materials[J].Journal of Geotechnical and Geoenvironmental Engineering,2004,130(9):896-904.
[15]NG C W W,ZHOU C,YUAN Q,et al.Resilient modulus of unsaturated subgrade soil:experimental and theoretical investigations[J].Canadian Geotechnical Journal,2013,50(2):223-232.
[16]FREDLUND D G,RAHARDJO H.Soil mechanics for unsaturated soils[M].New York:Wiley-Interscience,1993.
[17]YANG S R,LIN H D,KUNG J H,et al.Suction-controlled laboratory test on resilient modulus of unsaturated compacted subgrade soils[J].Journal of Geotechnical and Geoenvironmental Engineering,2008,134(9):1375-1384.
[18]KHOURY N,BROOKS R,KHOURY C,et al.Modeling resilientmodulus hysteretic behavior with moisture variation[J].International Journal of Geomechanics,2012,12(5):519-527.
[19]SALOUR F,ERLINGSSON S,ZAPATA C E.Modelling resilient modulus seasonal variation of silty sand subgrade soils with matric suction control[J].Canadian Geotechnical Journal,2014,51(12):1413-1422.
[20]HAN Z,VANAPALLI S K.Relationship between resilient modulus and suction for compacted subgrade soils[J].Engineering Geology,2016,211:85-97.
[21]ZAMAN M,SOLANKI P,EBRAHIMI A,et al.Neural network modeling of resilient modulus using routine rubgrade soil properties[J].International Journal of Geomechanics,2010,10(1):1-12.
[22]YAN K Z,XU H B,SHEN G H.Novel approach to resilient modulus using routine subgrade soil properties[J].International Journal of Geomechanics,2014,14(6):04014025.
[23]ZHOU C J,HUANG B S,DRUMM E,et al.Soil resilient modulus regressed from physical properties and influence of seasonal variation on asphalt pavement performance[J].Journal of Transportation Engineering,2015,141(1):04014069.
[24]AASHTO.Designation T307-99:determining the resilient modulus of soils and aggregate materials[S].Washington:American Association of State Highway and Transportation Officials,2003.
[25]ASTM Designation:D5298-10.Standard test method for measurement of soil potential(suction)using filter paper[S].West Conshohocken,PA:American Society for Testing and Materials,2010.
[26]LEONG E C,HE L,RAHARDJO H.Factors affecting the filter paper method for total and matric suction measurements[J].Geotechnical Testing,2002,25(3):322-333.
[27]FREDLUND D G,XING A.Equation for the soil-water characteristic curve[J].Canadian Geotechnical Journal,1994,31:521-532.
[28]JTG D30-2015公路路基设计规范[S].2015.(JTG D30-2015 Specification for design of highway subgrades[S].2015.(in Chinese))
[29]HAN Z,VANAPALLI S K,ZOU W L.Integrated approaches for predicting soil-water characteristic curve and resilient modulus of compacted fine-grained subgrade soils[J].Canadian Geotechnical Journal,2017,54(5):646-63.
[30]KHALILI N,KHABBAZ M H.A unique relationship for the determination of the shear strength of unsaturated soils[J].Géotechnique,1998,48(2):1-7.
[31]VANAPALLI S K,FREDLUND D G,PUFAHL D E,et al.Model for the prediction of shear Strength with respect to soil suction[J].Canadian Geotechnical Journal,1996,33(3):379-392.
[32]GARVEN E A,VANAPALLI S K.Evaluation of empirical procedures for predicting the shear strength of unsaturated soils[C]//ASCE.Proceedings of the 4th International Conference on unsaturated Soils.Carefree,2006:2570-2581.
[33]GUPTA S C,RANAIVOSON A,EDIL T B,et al.Pavement design using unsaturated soil technology[R].Minnesota:Minnesota Department of Transportation,St.Paul,2007.
[34]兰伟.路基土非饱和特性及回弹模量预估模型[D].上海:同济大学,2009.(LAN Wei.Unsaturated characteristics and prediction model of and resilient modulus of subgrade soil[D].Shanghai:Tongji University,2009.(in Chinese))