Analysis and design of axially loaded piles in rock
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摘要
Despite significant advancements in in situ test techniques, construction practices, understanding of rock joint and rock mass behaviours, and numerical analysis methods, the design of bored concrete cast-insitu piles in rock is still largely based on the assessment of bearing capacity. However, for many of the rock conditions encountered, the bearing capacity of piles is a nebulous concept and a figment of the designer's imagination. Even if it can be reasonably quantified, it has little, if any, significance to the performance of a pile in rock. The load carrying capacity of even low strength rock(in most situations) is far in excess of the strength of the structure(for example, a building column) transmitting the load.Unsatisfactory performance of a pile in rock is usually a displacement issue and is a function of rock mass stiffness rather than rock mass strength. In addition, poor pile performance is much more likely to result from poor construction practices than excessive displacement of the rock mass. Exceptions occur for footings that are undermined, or where unfavourable structure in the rock allows movement towards a free surface to occur. Standards, codes of practices, reference books and other sources of design information should focus foundation design in rock on displacement rather than strength performance.Ground investigations should measure rock mass stiffness and defect properties, as well as intact rock strength. This paper summarises the fundamental concepts relating to performance of piles in rock and provides a basis for displacement focused design of piles in rock. It also presents comments relating to how piles are modelled in widely used commercial finite element software for soil-structure interaction analysis, within the context of the back-analysis of a pile load test, and proposes recommendations for pile analysis and design.
Despite significant advancements in in situ test techniques, construction practices, understanding of rock joint and rock mass behaviours, and numerical analysis methods, the design of bored concrete cast-insitu piles in rock is still largely based on the assessment of bearing capacity. However, for many of the rock conditions encountered, the bearing capacity of piles is a nebulous concept and a figment of the designer's imagination. Even if it can be reasonably quantified, it has little, if any, significance to the performance of a pile in rock. The load carrying capacity of even low strength rock(in most situations) is far in excess of the strength of the structure(for example, a building column) transmitting the load.Unsatisfactory performance of a pile in rock is usually a displacement issue and is a function of rock mass stiffness rather than rock mass strength. In addition, poor pile performance is much more likely to result from poor construction practices than excessive displacement of the rock mass. Exceptions occur for footings that are undermined, or where unfavourable structure in the rock allows movement towards a free surface to occur. Standards, codes of practices, reference books and other sources of design information should focus foundation design in rock on displacement rather than strength performance.Ground investigations should measure rock mass stiffness and defect properties, as well as intact rock strength. This paper summarises the fundamental concepts relating to performance of piles in rock and provides a basis for displacement focused design of piles in rock. It also presents comments relating to how piles are modelled in widely used commercial finite element software for soil-structure interaction analysis, within the context of the back-analysis of a pile load test, and proposes recommendations for pile analysis and design.
Despite significant advancements in in situ test techniques, construction practices, understanding of rock joint and rock mass behaviours, and numerical analysis methods, the design of bored concrete cast-insitu piles in rock is still largely based on the assessment of bearing capacity. However, for many of the rock conditions encountered, the bearing capacity of piles is a nebulous concept and a figment of the designer's imagination. Even if it can be reasonably quantified, it has little, if any, significance to the performance of a pile in rock. The load carrying capacity of even low strength rock(in most situations) is far in excess of the strength of the structure(for example, a building column) transmitting the load.Unsatisfactory performance of a pile in rock is usually a displacement issue and is a function of rock mass stiffness rather than rock mass strength. In addition, poor pile performance is much more likely to result from poor construction practices than excessive displacement of the rock mass. Exceptions occur for footings that are undermined, or where unfavourable structure in the rock allows movement towards a free surface to occur. Standards, codes of practices, reference books and other sources of design information should focus foundation design in rock on displacement rather than strength performance.Ground investigations should measure rock mass stiffness and defect properties, as well as intact rock strength. This paper summarises the fundamental concepts relating to performance of piles in rock and provides a basis for displacement focused design of piles in rock. It also presents comments relating to how piles are modelled in widely used commercial finite element software for soil-structure interaction analysis, within the context of the back-analysis of a pile load test, and proposes recommendations for pile analysis and design.
引文
Baycan S.Improving the capacity of bored piles and ground anchors using expansive concretes.PhD Thesis.Melbourne,Australia:Department of Civil Engineering,Monash University;1997.
Benson N,Haberfield CM.Assessment of rock mass modulus.In:The 10th International congress on rock mechanics.Johannesburg,South Africa:International Society for Rock Mechanics and Rock Engineering;2003.p.103e6.
British Standards Institution(BSI).BS EN 1997 Eurocode 7:geotechnical design.British Standards Institution(BSI);2004.
Cheng FKK.A laboratory study of the influence of wall smear and residential drilling fluids on rock socketed pile performance.PhD Thesis.Melbourne,Australia:Department of Civil Engineering,Monash University;1997.
Cheng F,Haberfield CM,Seidel JP.Laboratory study of the effect of drilling fluids on socketed pile performance in weak rock.In:The 2nd International conference on hard soils e soft rock.Napoli,Italy:A.A.Balkema;1998.p.93e101.
Collingwood B.The effect of construction practises on the performance of rock socketed piles.PhD Thesis.Melbourne,Australia:Department of Civil Engineering,Monash University;2000.
Coyle HM,Reese LC.Load transfer for axially loaded piles in clay.Journal Soil Mechanics and Found Engineering Division 1966;92(SM2):1e26.
Ervin MC,Finlayson JE.Piled foundations for Eureka tower,Melbourne,Australia.Proceedings of the Institution of Civil Engineers,Geotechnical Engineering2006;159(3):187e94.
Haberfield CM,Johnston IW.A mechanistically based model for rough rock joints.International Journal of Rock Mechanics and Mining Sciences 1994;31(4):279e92.
Haberfield CM,Seidel JP.The role of theoretical models in the analysis and design of rock socketed piles.In:Smith DW,Carter JP,editors.Proceedings of the John booker memorial symposium.Sydney Australia:CRC Press;2000.p.465e88.
Haberfield CM.Davis EH Memorial Lecture 2007:performance of footings in rock based on serviceability.Australian Geomechanics 2013;48(1):1e50.
Holden JC.Construction of bored piles in weathered rocks.Research report No.34.Melbourne,Australia:Road Construction Authority of Victoria;1984.
Hoek E,Diederichs MS.Empirical estimation of rock mass modulus.International Journal of Rock Mechanics and Mining Sciences 2006;43(2):203e15.
Horvath RG.Behaviour of rock-socketed drilled pier foundations.PhD Thesis.Toronto,Canada:University of Toronto;1982.
Horvath RG,Kenny TC,Kozicki P.Methods for improving the performance of drilled piers in weak rock.Canadian Geotechnical Journal 1983;20(4):758e72.
Indraratna B,Haque A,Aziz N.Laboratory modelling of shear behaviour of soft joints under constant normal stiffness conditions.Geotechnical and Geological Engineering 1998;16(1):17e44.
Johnston IW.Rock-socketing down-under.Contract Journal 1977;279:50e3.
Johnston IW,Chiu HK.Strength of weathered Melbourne mudstone.Journal of Geotechnical Engineering 1984;110(7):875e98.
Johnston IW,Choi SK.Failure mechanisms of foundations in soft rock.In:Proceedings of the 11th International conference on soil mechanics and foundation engineering.San Francisco,USA.Rotterdam:A.A.Balkema;1985.p.1397e400.
Johnston IW,Lam TSK.Shear behaviour of regular triangular concrete/rock joints e Analysis.Journal of Geotechnical Engineering 1989;115(5):711e27.
Kodikara JK,Johnston IW.Shear behaviour of irregular triangular rock-concrete joints.International Journal of Rock Mechanics and Mining Sciences and Geomechanics Abstracts 1994a;31(4):313e22.
Kodikara JK,Johnston IW.Analysis of compressible axially loaded piles in rock.International Journal for Numerical and Analytical Methods in Geomechanics1994b;18(6):427e37.
Ladanyi B,Archambault G.Simulation of shear behavior of a jointed rock mass.In:Proceedings of the 11th symposium on rock mechanics(USRMS).American Rock Mechanics Association;1969.p.105e25.
Lam TSK,Johnston IW.Shear behaviour of regular triangular concrete/rock jointsEvaluation.Journal of Geotechnical Engineering 1989;115(5):728e40.
Majano RE,O’Neill MW.Effect of dosage and exposure time of slurries on perimeter load transfer in bored piles.In:Proceedings of the 2nd International geotechnical seminar on deep foundations on bored and auger piles.Rotterdam:A.A.Balkema;1993.p.207e12.
Ni P,Song L,Mei G,Zhao Y.Generalized nonlinear softening load-transfer model for axially loaded piles.International Journal of Geomechanics 2017;17(8).https://doi.org/10.1061/(ASCE)GM.1943-5622.0000899.
O’Neill MW,Townsend FC,Hassan KM,Buller A,Chan PS.Load transfer for drilled shafts in intermediate geomaterials.Draft report FHWA-RD-95-172.Virginia,USA:US Department of Transportation,Federal Highway Administration;1995.
Ooi LH,Carter JP.Constant normal stiffness direct shear device for static and cyclic loading.Geotechnical Testing Journal 1987;10(1):3e12.
Patton FD.Multiple modes of shear failure in rock.In:Proceedings of the 1st congress International society for rock mechanics.Lisbon:International Society for Rock Mechanics and Rock Engineering(ISRM);1966.p.509e13.
Pearce H,Haberfield CM.Direct shear testing of Melbourne mudstone joints under constant normal stiffness conditions.In:GeoEng2000 ISRM International symposium.International Society for Rock Mechanics and Rock Engineering(ISRM);2000.
Pearce H.A micro-mechanical approach to the shear behaviour of rock joints.PhDThesis.Melbourne,Australia:Department of Civil Engineering,Monash University;2001.
Pells PJN,Rowe RK,Turner RM.An experimental investigation into side shear for socketed piles in sandstone.In:International conference on structural foundations on rock.Sydney,Australia:A.A.Balkema;1980.p.291e302.
PLAXIS.PLAXIS 2D manual(version 2018).PLAXIS;2018.
Poulos HG,Davis EH.Elastic solutions for soil and rock mechanics.New York:John Wiley and Sons Inc.;1974.
Randolph MF.RATZ manual version 4.2:load transfer analysis of axially loaded piles.Perth,Australia:RATZ Software Manual;2003.
Reeves MJ.Rock surface roughness and frictional strength.International Journal of Rock Mechanics and Mining Sciences and Geomechanics Abstracts 1985;22(6):429e42.
Rowe RK,Armitage HH.The design of piles socketed into weak rock.Report GEOT-11-84.London,Canada:University of Western Ontario;1984.
Seidel JP.The analysis and design of pile shafts in weak rock.PhD Thesis.Melbourne,Australia:Department of Civil Engineering,Monash University;1993.
Seidel JP,Haberfield CM.Towards an understanding of joint roughness.Rock Mechanics and Rock Engineering 1995a;28(2):69e92.
Seidel JP,Haberfield CM.The axial capacity of pile sockets in rocks and hard soils.International Journal of Rock Mechanics and Mining Sciences and Geomechanics Abstracts 1995b;32(5):33e8.
Seidel JP,Gu XF,Haberfield CM.A new factor for improved prediction of the resistance of pile shafts in rock.In:7th ANZ conference on Geomechanics.Adelaide,Australia:Institution of Engineers Australia;1996.p.693e7.
Seidel JP,Collingwood B.An improved socket roughness factor for prediction of rock shaft resistance.Canadian Geotechnical Journal 2001;38(1):138e53.
Seidel JP,Haberfield CM.Laboratory testing of concrete-rock joints in constant normal stiffness direct shear.Geotechnical Testing Journal 2002a;25(4):391e404.
Seidel JP,Haberfield CM.A theoretical model for rock joints subjected to constant normal stiffness direct shear.International Journal of Rock Mechanics and Mining Sciences 2002b;39(5):539e54.
Seol H,Jeong S.Loadesettlement behavior of rock-socketed drilled shafts using Osterberg-Cell tests.Computers and Geotechnics 2009;36(7):1134e41.
Seol H,Jeong S,Cho S.Analytical method for load-transfer characteristics of rocksocketed drilled shafts.Journal of Geotechnical and Geoenvironmental Engineering 2009;135(6):778e89.
Sluis JJM.Validation of embedded pile row in PLAXIS 2D.MSc Thesis.Delft,The Netherlands:Delft University of Technology;2012.
Sluis JJM,Besseling F,Stuurwold PHH.Modelling of a pile row in a 2D plane strain FE-analysis.In:Proceedings of the 8th European conference on numerical methods in geotechnical engineering.Delft,The Netherlands:Taylor&Francis;2014.p.227e82.
Standards Australia.AS3600 concrete structures.Sydney,Australia.2009.
Tomlinson MJ,Woodward J.Pile design and construction practice.4th ed.1997.Spon.
Williams AF.The design and performance of piles socketed into weak rock.PhDThesis.Melbourne,Australia:Department of Civil Engineering,Monash University;1980.
Williams AF,Ervin MC.The design and performance of cast-in-situ piles in extensively jointed Silurian mudstone.In:3rd ANZ conference on Geomechanics.Wellington,New Zealand.New Zealand Geomechanics Society;1980.p.115e21.
Williams AF,Johnston IW,Donald IB.The design of socketed piles in weak rock.In:International conference on structural foundations on rock.Sydney,Australia:A.A.Balkema;1980.p.327e47.
Xu M,Ni P,Mei G,Zhao Y.Load-settlement behaviour of bored piles with loose sediments at the pile tip:experimental,numerical and analytical study.Computers and Geotechnics 2018;102:92e101.
Zhang L,Einstein HH.End bearing capacity of drilled shafts in rock.Journal of Geotechnical and Geoenvironmental Engineering 1998;124(7):574e84.
Zhang QQ,Zhang ZM,He JY.A simplified approach for settlement analysis of single pile and pile groups considering interaction between identical piles in multilayered soils.Computers and Geotechnics 2010;37(7):969e76.
Zhang QQ,Zhang ZM.A simplified nonlinear approach for single pile settlement analysis.Canadian Geotechnical Journal 2012;49(11):1256e66.
Benson N,Haberfield CM.Assessment of rock mass modulus.In:The 10th International congress on rock mechanics.Johannesburg,South Africa:International Society for Rock Mechanics and Rock Engineering;2003.p.103e6.
British Standards Institution(BSI).BS EN 1997 Eurocode 7:geotechnical design.British Standards Institution(BSI);2004.
Cheng FKK.A laboratory study of the influence of wall smear and residential drilling fluids on rock socketed pile performance.PhD Thesis.Melbourne,Australia:Department of Civil Engineering,Monash University;1997.
Cheng F,Haberfield CM,Seidel JP.Laboratory study of the effect of drilling fluids on socketed pile performance in weak rock.In:The 2nd International conference on hard soils e soft rock.Napoli,Italy:A.A.Balkema;1998.p.93e101.
Collingwood B.The effect of construction practises on the performance of rock socketed piles.PhD Thesis.Melbourne,Australia:Department of Civil Engineering,Monash University;2000.
Coyle HM,Reese LC.Load transfer for axially loaded piles in clay.Journal Soil Mechanics and Found Engineering Division 1966;92(SM2):1e26.
Ervin MC,Finlayson JE.Piled foundations for Eureka tower,Melbourne,Australia.Proceedings of the Institution of Civil Engineers,Geotechnical Engineering2006;159(3):187e94.
Haberfield CM,Johnston IW.A mechanistically based model for rough rock joints.International Journal of Rock Mechanics and Mining Sciences 1994;31(4):279e92.
Haberfield CM,Seidel JP.The role of theoretical models in the analysis and design of rock socketed piles.In:Smith DW,Carter JP,editors.Proceedings of the John booker memorial symposium.Sydney Australia:CRC Press;2000.p.465e88.
Haberfield CM.Davis EH Memorial Lecture 2007:performance of footings in rock based on serviceability.Australian Geomechanics 2013;48(1):1e50.
Holden JC.Construction of bored piles in weathered rocks.Research report No.34.Melbourne,Australia:Road Construction Authority of Victoria;1984.
Hoek E,Diederichs MS.Empirical estimation of rock mass modulus.International Journal of Rock Mechanics and Mining Sciences 2006;43(2):203e15.
Horvath RG.Behaviour of rock-socketed drilled pier foundations.PhD Thesis.Toronto,Canada:University of Toronto;1982.
Horvath RG,Kenny TC,Kozicki P.Methods for improving the performance of drilled piers in weak rock.Canadian Geotechnical Journal 1983;20(4):758e72.
Indraratna B,Haque A,Aziz N.Laboratory modelling of shear behaviour of soft joints under constant normal stiffness conditions.Geotechnical and Geological Engineering 1998;16(1):17e44.
Johnston IW.Rock-socketing down-under.Contract Journal 1977;279:50e3.
Johnston IW,Chiu HK.Strength of weathered Melbourne mudstone.Journal of Geotechnical Engineering 1984;110(7):875e98.
Johnston IW,Choi SK.Failure mechanisms of foundations in soft rock.In:Proceedings of the 11th International conference on soil mechanics and foundation engineering.San Francisco,USA.Rotterdam:A.A.Balkema;1985.p.1397e400.
Johnston IW,Lam TSK.Shear behaviour of regular triangular concrete/rock joints e Analysis.Journal of Geotechnical Engineering 1989;115(5):711e27.
Kodikara JK,Johnston IW.Shear behaviour of irregular triangular rock-concrete joints.International Journal of Rock Mechanics and Mining Sciences and Geomechanics Abstracts 1994a;31(4):313e22.
Kodikara JK,Johnston IW.Analysis of compressible axially loaded piles in rock.International Journal for Numerical and Analytical Methods in Geomechanics1994b;18(6):427e37.
Ladanyi B,Archambault G.Simulation of shear behavior of a jointed rock mass.In:Proceedings of the 11th symposium on rock mechanics(USRMS).American Rock Mechanics Association;1969.p.105e25.
Lam TSK,Johnston IW.Shear behaviour of regular triangular concrete/rock jointsEvaluation.Journal of Geotechnical Engineering 1989;115(5):728e40.
Majano RE,O’Neill MW.Effect of dosage and exposure time of slurries on perimeter load transfer in bored piles.In:Proceedings of the 2nd International geotechnical seminar on deep foundations on bored and auger piles.Rotterdam:A.A.Balkema;1993.p.207e12.
Ni P,Song L,Mei G,Zhao Y.Generalized nonlinear softening load-transfer model for axially loaded piles.International Journal of Geomechanics 2017;17(8).https://doi.org/10.1061/(ASCE)GM.1943-5622.0000899.
O’Neill MW,Townsend FC,Hassan KM,Buller A,Chan PS.Load transfer for drilled shafts in intermediate geomaterials.Draft report FHWA-RD-95-172.Virginia,USA:US Department of Transportation,Federal Highway Administration;1995.
Ooi LH,Carter JP.Constant normal stiffness direct shear device for static and cyclic loading.Geotechnical Testing Journal 1987;10(1):3e12.
Patton FD.Multiple modes of shear failure in rock.In:Proceedings of the 1st congress International society for rock mechanics.Lisbon:International Society for Rock Mechanics and Rock Engineering(ISRM);1966.p.509e13.
Pearce H,Haberfield CM.Direct shear testing of Melbourne mudstone joints under constant normal stiffness conditions.In:GeoEng2000 ISRM International symposium.International Society for Rock Mechanics and Rock Engineering(ISRM);2000.
Pearce H.A micro-mechanical approach to the shear behaviour of rock joints.PhDThesis.Melbourne,Australia:Department of Civil Engineering,Monash University;2001.
Pells PJN,Rowe RK,Turner RM.An experimental investigation into side shear for socketed piles in sandstone.In:International conference on structural foundations on rock.Sydney,Australia:A.A.Balkema;1980.p.291e302.
PLAXIS.PLAXIS 2D manual(version 2018).PLAXIS;2018.
Poulos HG,Davis EH.Elastic solutions for soil and rock mechanics.New York:John Wiley and Sons Inc.;1974.
Randolph MF.RATZ manual version 4.2:load transfer analysis of axially loaded piles.Perth,Australia:RATZ Software Manual;2003.
Reeves MJ.Rock surface roughness and frictional strength.International Journal of Rock Mechanics and Mining Sciences and Geomechanics Abstracts 1985;22(6):429e42.
Rowe RK,Armitage HH.The design of piles socketed into weak rock.Report GEOT-11-84.London,Canada:University of Western Ontario;1984.
Seidel JP.The analysis and design of pile shafts in weak rock.PhD Thesis.Melbourne,Australia:Department of Civil Engineering,Monash University;1993.
Seidel JP,Haberfield CM.Towards an understanding of joint roughness.Rock Mechanics and Rock Engineering 1995a;28(2):69e92.
Seidel JP,Haberfield CM.The axial capacity of pile sockets in rocks and hard soils.International Journal of Rock Mechanics and Mining Sciences and Geomechanics Abstracts 1995b;32(5):33e8.
Seidel JP,Gu XF,Haberfield CM.A new factor for improved prediction of the resistance of pile shafts in rock.In:7th ANZ conference on Geomechanics.Adelaide,Australia:Institution of Engineers Australia;1996.p.693e7.
Seidel JP,Collingwood B.An improved socket roughness factor for prediction of rock shaft resistance.Canadian Geotechnical Journal 2001;38(1):138e53.
Seidel JP,Haberfield CM.Laboratory testing of concrete-rock joints in constant normal stiffness direct shear.Geotechnical Testing Journal 2002a;25(4):391e404.
Seidel JP,Haberfield CM.A theoretical model for rock joints subjected to constant normal stiffness direct shear.International Journal of Rock Mechanics and Mining Sciences 2002b;39(5):539e54.
Seol H,Jeong S.Loadesettlement behavior of rock-socketed drilled shafts using Osterberg-Cell tests.Computers and Geotechnics 2009;36(7):1134e41.
Seol H,Jeong S,Cho S.Analytical method for load-transfer characteristics of rocksocketed drilled shafts.Journal of Geotechnical and Geoenvironmental Engineering 2009;135(6):778e89.
Sluis JJM.Validation of embedded pile row in PLAXIS 2D.MSc Thesis.Delft,The Netherlands:Delft University of Technology;2012.
Sluis JJM,Besseling F,Stuurwold PHH.Modelling of a pile row in a 2D plane strain FE-analysis.In:Proceedings of the 8th European conference on numerical methods in geotechnical engineering.Delft,The Netherlands:Taylor&Francis;2014.p.227e82.
Standards Australia.AS3600 concrete structures.Sydney,Australia.2009.
Tomlinson MJ,Woodward J.Pile design and construction practice.4th ed.1997.Spon.
Williams AF.The design and performance of piles socketed into weak rock.PhDThesis.Melbourne,Australia:Department of Civil Engineering,Monash University;1980.
Williams AF,Ervin MC.The design and performance of cast-in-situ piles in extensively jointed Silurian mudstone.In:3rd ANZ conference on Geomechanics.Wellington,New Zealand.New Zealand Geomechanics Society;1980.p.115e21.
Williams AF,Johnston IW,Donald IB.The design of socketed piles in weak rock.In:International conference on structural foundations on rock.Sydney,Australia:A.A.Balkema;1980.p.327e47.
Xu M,Ni P,Mei G,Zhao Y.Load-settlement behaviour of bored piles with loose sediments at the pile tip:experimental,numerical and analytical study.Computers and Geotechnics 2018;102:92e101.
Zhang L,Einstein HH.End bearing capacity of drilled shafts in rock.Journal of Geotechnical and Geoenvironmental Engineering 1998;124(7):574e84.
Zhang QQ,Zhang ZM,He JY.A simplified approach for settlement analysis of single pile and pile groups considering interaction between identical piles in multilayered soils.Computers and Geotechnics 2010;37(7):969e76.
Zhang QQ,Zhang ZM.A simplified nonlinear approach for single pile settlement analysis.Canadian Geotechnical Journal 2012;49(11):1256e66.