地震荷载作用下条形基础地基动承载力统一强度理论解
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摘要
基于考虑中主应力影响的统一强度理论,通过假定复合型滑动面,利用拟静力和极限平衡分析法得到了条形基础地基静、动承载力解答。对比分析研究发现:在条形基础地基静承载力方面,本文提出的基于统一强度理论地基承载力系数有不同程度的提高,说明现有方法中地基承载力系数比较保守;而在动承载力方面,不同地震荷载下条形地基动承载力系数Ncd变化不大在2%~6%之间,但动承载力系数Nqd、Nγd值均有20%~75%的降低,而地基承载力有15%~40%的下降。
Based on the unified strength theory which takes the effect of intermediate stress into consideration,by supposing composite curved rupture surfaces and employing pseudo-static approach and the method of limit equilibrium,the result of static,seismic bearing capacity of strip foundation is obtained.The comparative analysis shows that in the light of static bearing capacity of strip foundation,the bearing capacity coefficients will be improved in varying degrees when the method considering the unified strength theory is employed.That proves the bearing capacity coefficients obtained by the present way of calculation is smaller than real values.While in terms of seismic bearing capacity,under the operation of seismic loading,N_(cd) changes little(2%～6%)while N_(qd) and N_(γd) reduce by 20%～75%,the seismic bearing capacity is 15%～40% less than the static bearing capacity.
Based on the unified strength theory which takes the effect of intermediate stress into consideration,by supposing composite curved rupture surfaces and employing pseudo-static approach and the method of limit equilibrium,the result of static,seismic bearing capacity of strip foundation is obtained.The comparative analysis shows that in the light of static bearing capacity of strip foundation,the bearing capacity coefficients will be improved in varying degrees when the method considering the unified strength theory is employed.That proves the bearing capacity coefficients obtained by the present way of calculation is smaller than real values.While in terms of seismic bearing capacity,under the operation of seismic loading,N_(cd) changes little(2%～6%)while N_(qd) and N_(γd) reduce by 20%～75%,the seismic bearing capacity is 15%～40% less than the static bearing capacity.
引文
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[2]Meyerhof G G.Some recent research on the bearingcapacity of foundations,The ultimatebearing capacity offoundations[J].Can.Geotech.J.,1963,1(1):16-26.
[3]Sarma S K,Iossifelis I S.Seismic bearing capacity factorsof shallow strip footings[J].Geotechnique,1990,40(2):265-273.
[4]Richards R,Elms D G,Budhu M.Seismic bearingcapacity and settlement of foundations[J].Geotech.Eng.,ASCE,1993,119(4):662-674.
[5]Dormieux L,Pecker A.Seismic bearing capacity offoundations on cohesionless soil[J].Geotech.Eng.,ASCE,1995,121(3):300-303.
[6]Soubra A H.Seismic bearing capacity of shallow stripfootings in seismic conditions[J].Geotech.Eng.ASCE,1997,125(4):230-241.
[7]Soubra A H.Upper bound solutions for bearing capacityof foundations[J].Geotech.Geoenviron.Eng.,ASCE,1999,125(1):59-69.
[8]俞茂宏.岩土类材料的统一强度理论及其应用[J].岩土工程学报,1994,16(2):1-10.
[9]范文.岩土工程结构强度理论研究[D].西安:西安交通大学博士学位论文,2003.
[10]张永强,范文,俞茂宏.边坡极限荷载的统一滑移线解[J].岩石力学与工程报,2000,19(增):994-996.
[11]俞茂宏,杨松岩,刘春阳,等.统一平面应变滑移线场理论[J].土木工程学报,1997,30(2):14-26.
[12]Deepankar Choudhury and Kanakapura S.Subba RaoSeismic bearing capacity of shallow strip footings[J].Geotechnicaland Geological Engineering,2005,23:403-418.
[13]K S.Subba Rao1,Deepankar Choudhury.SeismicPassive Earth Pressures in Soils[J].Journal ofGeotechnical and Geoenvironmental engineering ASCE,2005(4):131-135.
[14]尉学勇.斜坡地基承载力的仿真分析与理论计算[D].西安:长安大学硕士学位论文,2003.
[2]Meyerhof G G.Some recent research on the bearingcapacity of foundations,The ultimatebearing capacity offoundations[J].Can.Geotech.J.,1963,1(1):16-26.
[3]Sarma S K,Iossifelis I S.Seismic bearing capacity factorsof shallow strip footings[J].Geotechnique,1990,40(2):265-273.
[4]Richards R,Elms D G,Budhu M.Seismic bearingcapacity and settlement of foundations[J].Geotech.Eng.,ASCE,1993,119(4):662-674.
[5]Dormieux L,Pecker A.Seismic bearing capacity offoundations on cohesionless soil[J].Geotech.Eng.,ASCE,1995,121(3):300-303.
[6]Soubra A H.Seismic bearing capacity of shallow stripfootings in seismic conditions[J].Geotech.Eng.ASCE,1997,125(4):230-241.
[7]Soubra A H.Upper bound solutions for bearing capacityof foundations[J].Geotech.Geoenviron.Eng.,ASCE,1999,125(1):59-69.
[8]俞茂宏.岩土类材料的统一强度理论及其应用[J].岩土工程学报,1994,16(2):1-10.
[9]范文.岩土工程结构强度理论研究[D].西安:西安交通大学博士学位论文,2003.
[10]张永强,范文,俞茂宏.边坡极限荷载的统一滑移线解[J].岩石力学与工程报,2000,19(增):994-996.
[11]俞茂宏,杨松岩,刘春阳,等.统一平面应变滑移线场理论[J].土木工程学报,1997,30(2):14-26.
[12]Deepankar Choudhury and Kanakapura S.Subba RaoSeismic bearing capacity of shallow strip footings[J].Geotechnicaland Geological Engineering,2005,23:403-418.
[13]K S.Subba Rao1,Deepankar Choudhury.SeismicPassive Earth Pressures in Soils[J].Journal ofGeotechnical and Geoenvironmental engineering ASCE,2005(4):131-135.
[14]尉学勇.斜坡地基承载力的仿真分析与理论计算[D].西安:长安大学硕士学位论文,2003.
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