摘要
桩土相互作用问题是近年来桩基工程中的研究热点与难点课题。通常各类建筑工程中的桩基础主要是主动受荷桩，即上部结构的荷载通过承台传递给下部的桩基础，由桩土间的相互作用来分担上部结构荷载。然而，在桩基工程中仍有许多情况是桩基承受被动荷载，即桩周土体竖向或水平运动行为引入的荷载，如粘性土的固结、膨胀土的膨胀或沉降、隧道的开挖、洞穴扩展及边坡滑动等对桩基础所产生的荷载。其表现为在桩基中引起附加作用力和附加应力，这将对桩基的承载机制与变形特性产生重要的影响。
本文针对大面积地面堆载条件下的邻近桩基进行分析，假定桩为简单的弹性地基梁，而桩周土作为弹塑性变形体。基于桩与土的变形协调条件，确定桩侧土压力的表达式，在此基础上建立桩身挠曲控制微分方程，联合采用非线性p-y曲线与有限差分法进行求解，并编制了相应的计算程序。通过算例分析，验证了所建议分析方法的合理性和实用性。同时，对影响被动桩桩—土体系变形的各种复杂因素进行了系统的比较分析，结果表明：桩的水平位移与桩的抗弯刚度以及桩土间水平作用力密切相关，相应的桩周土的位移取决于土体强度、桩土间相互作用力以及自由场地的土体水平运动等。通过分析还得出了其它一些有意义的结论。
The issue of pile-soil interaction is the research hotspot and difficult subject in pile foundation engineering for recently several years. The majority of piles are designed to support "active" loadings, that is to say, loads from upper structure are directly transferred to the pile foundation by the cap. However, there are many cases in which the piles have to withstand "passive" loading, i.e. loads in the piles are often induced by the movement of soils past the piles vertically and/or horizontally. Examples include consolidation of clay; swelling or shrinking of an expansive clay; tunneling; excavation; cavity development; slope movement. These externally-imposed soil movements will lead to additional forces and stresses into pile foundations. Therefore, it is very important to reasonably assess these forces and the corresponding effects on the bearing and deformation performance of pile foundation.
This paper analyzes the pile-soil interaction adjacent to superficial surcharge, the pile is modeled simple elastic foundation beam, soil to be elastic-plastic deformation body. Based on the compatibility condition of deformation of piles and surrounding soils, the expression formulation of lateral earth pressure on piles is presented. And then the partial differential equation for governing deflection of pile is established and is numerically solved by combining non-linear p-y relationship curve of pile and finite difference procedure. The author encodes the corresponding program. Through an example analysis, the reasonability and applicability of the proposed method are verified. Therefore this simplified method can be useful in evaluating the interaction behavior of pile and soils under passive state. Moreover, the author studies the complicated factors that affect the deformation of pile-soil system. The result indicates that the lateral displacement of the pile can be related to the pile bending stiffne
ss and horizontal pile-soil interaction stresses, the lateral displacement of the corresponding soil is related to the soil stiffness, the pile-soil interaction stresses, and the free-field horizontal soil movements, and so on. According to the comprehensive analyses, the author draws some significant conclusions.
引文
[1] De Beer E E. The effects of horizontal loads on piles, due to surcharge or seismic effects[A]. Proc 9th ICSMFE[C], Tokyo, 1977, 347-558.
[2] Franx C, Boonstra G C. Horizontal pressures on pile foundations[A]. Proc 2nd ICSMFE[C], Rotterdam, 1948, 4: 131-135
[3] Heyman L, Boersma F. Bending moments in piles due to lateral earth pressure[A]. Proc 5th ICSMFE[C], Paris, 1961, 2: 425-429
[4] Wenz K P. Large scale tests for determination of lateral loads on piles in soft cohesive soils[A]. Proc 8th ICSMFE[C]. Moscow, 1973, 2-2.
[5] Heyman L. Measurement of the influence of lateral earth pressure on pile foundations[A]. Proc 6th ICSMFE[C], Montreal, 1965, 2:257-260.
[6] Tavenas F, Mieussens C, Bourges F. Lateral displacements in clay foundations under embankments[J]. Canadian Geo technical Journal, 1979, 16(4):532-550.
[7] Nicu N D, Antes D R, Kessler R S. Field measurements on instrumented piles under an overpass abutment[R]. Highway Research Record, 1971, 354, 90-99.
[8] Oteo C S. Discussion to Poulos (1973)[J]. JSMFD, ASCE, 1974, 100(SM4):464-467.
[9] Oteo C S. Horizontally loaded piles-deformation influence[A]. Proc 9th ICSMFE[C]. Special Session 10, Tokyo, 1977, 101-106.
[10] De Beer E E, Wallays M. Forces induced in piles by unsymmetrical surcharges on the soil around the piles[A]. Proc 5th ECSMFE[C]. Madrid, 1972, 1:325-332.
[11] Stewart D P, Jewell R J, Randolph M F. Design of piled bridge abutments on soft clay for loading from lateral soil movements[J]. Geotechnique, 1994, 44(2): 277-296.
[12] Begemann H- K S, De Leeuw E H. Horizontal earth pressures on piles as a result of nearby soil fills[A]. Proc 5th ECSMFE[C], Madrid, 1972, 1:3-9.
[13] Tschebotarioff G P. Foundations, Retaining, and Earth Structures[M]. New York: Mc Graw-Hill, 1973.
[14] Franke E. German recommendations on passive piles[A]. Proc 9th ICSMFE[C]. Special Session 10, Tokyo, 1977, 193-194.
[15] Poulos H G. Analysis of piles in soil undergoing lateral movement[J]. JSMFD, ASCE, 1973, 99(SM5): 391-406.
[16] Marche R, Schneeberger C E. Bending moments prediction in piles subjected to horizontal soil movements, Proc 9th CSMFE, Special Session10, Tokyo, 1997, 98-99.
[17] Bransby M F, Springman S M. 3-D finite element modeling of pile groups adjacent to surcharge loads[J]. Computers and Geotechnics, 1996, 19(4):301-324.
[18] 王年香，魏汝龙．岸坡上桩基码头设计方案的分析比较[J]．水利水运科学研究，1995，(1)：43-54．
[19] Matsui T, Hong W P, Ito T. Earth pressure on piles in a row due to lateral soil movements[J]. Soils and Foundations, 1982, 22(2): 71-81.
[20] Ito T, Matsui T. Methods to estimate lateral force acting on stabilizing piles[J]. Soil and Foundations, 1975, 14(4): 43-59.
[21] 马骥．单根抗滑桩受力条件的实验研究[A]．滑坡文集(第5集)[C]．北京：中国铁道出版社，1986，88-96．
[22] 沈珠江．桩的抗滑阻力和抗滑桩的极限设计[J]．岩土工程学报，1992，14(1)：51-56．
[23] 魏汝龙，王年香，杨守华．桩基码头和岸坡的相互作用[J]．岩土工程学报，1992，14(6)：38-49．
[24] 陈永战．高桩码头岸坡与桩基相互作用实验研究[D]．南京：南京水利科学研究院，1991．
[25] JTJ2．19-87，港口工程技术规范(下卷)[S]．
[26] Ito T, Matsui T, Hong W P. Design method for the stability analysis of the slope with landing pier[J]. Soils and Foundations, 1979, 19(4):43-56.
[27] Lee C Y, Hull S T, Poulos H G. Simplified pile-slope stability analysis[J]. Computers and Geoteehnies, 1995, 17:1-16.
[28] Viggiani C. U ltimate lateral load on piles used to stabilize landslides[A]. Proe 10th ICSMFE[C]. Stockholm, 1981, 3:555-560.
[29] Lee C Y, Poulos H G, Hull S T. Effect of seafloor instability on offshore pile foundations[J]. Canadian Goetechnical Journal, 1991, 28: 729-737.
[30] 王年香．码头桩基与岸坡相互作用的数值模拟和简化计算方法研究[D]．南京：南京水利科学研究院，1998．
[31] 王年香．桩基码头岸坡稳定和桩基性状的简化分析[J]．水利水运科学研究，2000，(1)：1-9．
[32] M Fraser Bransby, Sarah Springman. Selection of load-transfer function for passive lateral loading of
pile groups[J]. Computers and Geotechnics, 1999, 24:155-184.
[33] 杨敏，朱碧堂．堆载地基与邻近桩基的相互作用分析[J]．水文地质工程地质。2002，(3)：1-5．
[34] 魏焕卫，杨敏．大面积堆载情况下邻桩的有限元分析[J]．工业建筑，2000，30(8)：30-33．
[35] K J Xu, H G Poulos. 3-Delastic analysis of vertical piles subjected to "passive" loadings[J]. Computers and Geotechnics, 2001, 28: 349-375.
[36] L T Chen, H G Poulos. Piles subject to lateral soil movement[J]. Journal of Geotechnical and Geoenvironmental Engineering, 1997, 123(9):802-811.
[37] A T C Goh, C I The, K S Wong. Analysis of piles subjected to embankment induced lateral soil movements[J]. Journal of Geotechnical and Geoenvironmental Engineering, 1997, 123(9):792-801.
[38] H G Poulos, L T Chen. Pile response due to excavation-induced lateral soil movement[J]. Journal of Geotechnical and Geoenvironmental Engineering, 1997, 123(2):94-99.
[39] Hudson Matlock. Correlations for design of laterally loaded piles in soft clay. Offshore Technology Conference on Behalf of American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc., 1970, 4:577-588.
[40] 屠毓敏．承受超载作用的桩基性状研究[J]．土木工程学报，2002，35(1)：79-82．
[41] 楼晓明，刁惠荣．非粘土地基灌注桩超载受压后的承载性状[J]．工程勘察，1999，(1)：17-23．
[42] 刘义怀，朱志铎，刘松玉．路堤荷载下碎石桩复合地基的有限元分析[J]．公路交通科技，2002，19(5)：11-13．
[43] 谢耀峰．大变位水平承载高桩性状的研究[J]．土木工程学报，2000，33(4)：74-79．
[44] 李仁平，陈仁朋，陈云敏．软土地基码头的加固及堆载实验分析[J]．港工技术，2001，(3)：34-37．
[45] 邵军义，朱珊．堆载下软土地基及桩的侧向位移[J]．金属矿山，1994，(7)：30-33．
[46] 王广月．地下结构局部超载侧压力计算[J]．岩土工程技术，1997，1：35-41．
[47] H G Poulos. Analysis and design of pile through embankments. International conference on design and construction of deep foundations. Orlando: FL, 1994. 3: 1403-1421.
[48] L T Chen, H G Poulos, T S Hull. Model tests on pile groups subjected to lateral soil movement[J]. Soil and Foundations, 1996.
[49] M F Bransby, S M Springman. 3-Dfinite element modeling of pile groups adjacent to surcharge loads[J]. Computers and Geotechnics, 1996, 19(4):301-324.
[50] M F Bransby. The difference between load-transfer relationships for laterally loaded pile groups:
active p-y or passive p-δ [J]. J of Geotech Eng, 1996, 122(12):1015-1018.
[51] 《桩基工程手册》编写委员会．桩基工程手册．中国建筑工业出版社，1995．764-785．
[52] 徐芝纶．弹性力学中的差分方法．第二版．高等教育出版社．
[53] 李有法．数值计算方法．北京：高等教育出版社，1996．
[54] 叶万灵．地基反力法确定侧向承载桩的受力特性[J]．港工技术与管理，1990，(1)：6-14．
[55] 卢世深，林亚超．桥梁钻孔桩试验[M]．北京：人民交通出版社，1980，184-225．
[56] 胡人礼．桥梁桩基础分析和设计．北京：中国铁道出版社，1987，90-112．
[56] 王成．水平荷载作用下钢筋混凝土桩的损伤断裂研究及其桩土共同作用全过程分析[D]．重庆：重庆建筑大学，2000．
[57] 王成，陈志刚等．钻孔灌注推力桩桩土参数取值范围的研究[J]．岩土工程学报，1993，15(3)：101-105．
[58] 建筑桩基技术规范[S]．北京：中国建筑工业出版社，1995．
[59] 沈新普，岑章志，徐秉业．弹脆塑性软化本构理论的特点及其数值计算[J]．清华大学学报(自然科学版)，1995，35(2)：22-27．
[60] 吴恒立．计算推力桩的综合刚度原理和双参数法[M]．北京：人民交通出版社，1990．
[61] 吴恒立．推力桩计算方法的研究[J]．土木工程学报，1995，28(2)：20-28．
[62] 廖雄华．桩-土相互作用数值方法的研究及其在高桩码头安全性分析中的应用[D]．哈尔滨：哈尔滨工业大学，2000年．
[63] 魏汝龙，杨守华，王年香．桩基码头和岸坡的相互作用[J]．岩土工程学报，1992，(3)：37-45．
[64] 魏汝龙．桩基码头与岸坡土体的相互作用[J]．岩土工程学报，1994，14(6)：41-56．
[65] 魏汝龙．软粘土的强度和变形[M]．北京：人民交通出版社，1987．
[66] Nash D. A comparative review of limit-equilibrium methods of stability analysis[A]. In: Andersen M G, Richards K S. Slope stability[C]. New York: Willey, 1987.
[67] Bishop A W. The use of the slip circle in the stability analysis of slopes[J]. Geotechnique, 1955, 5(1):7-17.
[68] Spencer E A. Method of analysis of the stability of embankments assuming parallel inter-slice forces[J]. Geotechnique, 1967, 17(1): 1-26.
[69] Morgenstern N R, Price V E. The analysis of the stability of general slip surfaces[J]. Geoteehnique,
1965, 15(1): 79-93.
[70] Sarma S K. Stability analysis of embankments and slopes[J]. Geotechnique, 1973, 23(3).
[71] Whitman R V, Bailey W A. Use of computers for slope stability analysis[J]. JSMFD, ASCE, 1967, 93 (SM4):475-498.
[72] Anderheggen E, Knopfel H. Finite element limit analysis using linear programming[J]. International Journal of Solids and Structures, 1972, 8(12):1413-1431.
[73] Jiang G T, Magnan J P. Stability analysis of embankments: comparison of limit analysis with methods of slices[J]. Geotechnique, 1997, 47(4):857-872.
[74] 汪肇京．土坡与地基稳定分析的程序[J]．水利水运科技情报，1975，(3)：58-80．
[75] Ito T, Matsui T, Hong W P. Design method for the stability analysis of the slope with landing pier[J]. Soils and Foundation, 1979, 19(4):43-56.
[76] Lee C Y, Hull S T, Poulos H G. Simplified pile-slope stability analysis[J]. Computers and Geotechnics, 1995, (17):1-16.
[77] Reese L C, Welch R C. lateral loading of deep foundations in stiff clay. J Geotech Engineering Div, 1975, 101(7):633-649.
[78] Duncan J M, Evans L T Jr, Ooi P S K. lateral load analysis of single pile sand drilled sharfts. J Geotech Engineering, 1994, 120(6): 1018-1033.