Mindlin解均化应力法计算桩基沉降及工程应用
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摘要
基于群桩Mindlin应力解附加应力场和群桩基础变形分布特征,考虑承台和上部结构刚度对沉降变形的均化效应,总结了Mindlin解均化应力分层总和法计算群桩基础沉降的具体步骤细则。针对计算中具体问题,诸如压缩层计算厚度、上部结构刚度贡献、变刚度调平设计中桩类型的多样性,结合特定侧阻分布概化模式不同长径比、不同桩距条件给出基桩均化附加应力计算简易方法。应用所提供的均化附加应力计算方法计算群桩沉降,通过工程实例验证,与Boussinesq实体深基础计算法和等效作用计算法比较,其沉降计算值与实测竣工沉降值较为接近。
Based on the stress field calculated by the Mindlin stress theory and the existing Mindlin homogenization stress summation method for calculating the pile group foundation settlement, the deformation behavior of the pile-group foundation as well as the homogenization effect of pile cap and the superstructure stiffness on the settlement deformation was considered, and the detailed steps of Mindlin solution homogenized additional stress layer summation method to calculate the settlement of pile group foundation was concluded.Many specific problems exist in the calculation, such as the compression layer calculation thickness, the rigidity contribution of superstructure, the pile type diversity of optimized design of pile foundation stiffness to reduce differential settlement. A simplified method for calculating the homogenization additional stress of pile is presented based on the specific shaft resistance distribution model, the ratio of length to diameter and the distance between piles. Compared with Boussinesq deep foundation calculation method and equivalent calculation method, the proposed method in this paper can provide better settlement calculation values close to the tested ones.
Based on the stress field calculated by the Mindlin stress theory and the existing Mindlin homogenization stress summation method for calculating the pile group foundation settlement, the deformation behavior of the pile-group foundation as well as the homogenization effect of pile cap and the superstructure stiffness on the settlement deformation was considered, and the detailed steps of Mindlin solution homogenized additional stress layer summation method to calculate the settlement of pile group foundation was concluded.Many specific problems exist in the calculation, such as the compression layer calculation thickness, the rigidity contribution of superstructure, the pile type diversity of optimized design of pile foundation stiffness to reduce differential settlement. A simplified method for calculating the homogenization additional stress of pile is presented based on the specific shaft resistance distribution model, the ratio of length to diameter and the distance between piles. Compared with Boussinesq deep foundation calculation method and equivalent calculation method, the proposed method in this paper can provide better settlement calculation values close to the tested ones.
引文
[1]邱明兵,刘金砺,秋仁东,等.基于Mindlin解的单桩竖向附加应力系数[J].土木工程学报,2014,47(3):130-137(Qiu Mingbing,Liu Jinli,Qiu Rendong,et al.Study on vertical additional stress coefficient research for the single piles based on mindlin’s stress solution theory[J].China Civil Engineering Journal,2014,47(3):130-137(in Chinese))
[2]刘金砺,秋仁东,邱明兵,等.不同条件下桩侧阻力端阻力性状及侧阻力分布概化与应用[J].岩土工程学报,2014,36(11):1953-1970(Liu Jinli,Qiu Rendong,Qiu Mingbing,et al.Behaviors of shaft resistance and tip resistance of piles under different conditions and conceptualization and application of distribution of shaft resistance[J].Chinese Journal of Geotechnical Engineering,2014,36(11):1953-1970(in Chinese))
[3]刘金砺,邱明兵,秋仁东,高文生.Mindlin解均化应力分层总和法计算群桩基础沉降[J].土木工程学报,2014,47(5):118-127(Liu Jinli,Qiu Mingbing,Qiu Rendong,et al.A layerwise summation method for settlement calculation of pile group based on the homogenized Mindlin stress[J].China Civil Engineering Journal,2014,47(5):118-127(in Chinese))
[4]JGJ 94-2008建筑桩基技术规范[S].北京:中国建筑工业出版社,2008(JGJ 94-2008 Technical code for building pile foundation[S].Beijing:China Architecture and Building Press,2008(in Chinese))
[5]刘金砺,迟铃泉.桩土变形计算模型和变刚度调平设计[J].岩土工程学报,2000,22(2):151-157(Liu Jinli,Chi Lingquan.The modified model of pile-soil deformation calculation and variable rigidity design method for balance settlement[J].Chinese Journal of Geotechnical Engineering,2000,22(2):151-157(in Chinese))
[6]王涛,刘金砺,王旭.基于桩侧阻概化模式的基桩均化附加应力系数研究[J].岩土工程学报,2018,40(4):665-672(Wang Tao,Liu Jinli,Wang Xu.Homogenized additional stress coefficient of foundation piles based on generalized mode of pile shaft resistance[J].Chinese Journal of Geotechnical Engineering,2018,40(4):665-672(in Chinese))
[7]Mindlin R D.Force at a point in the interior of a semiinfinite solid[J].Journal of Applied Physics,2004,7(5):195-202
[8]Geddes J D.Stresses in foundation soils due to vertical subsurface loading[J].Geotechnique,1966,16(3):231-255
[9]DGJ 08-11-2010地基基础设计规范[S].上海:上海市建筑建材业市场管理总站,2010(DGJ 08-11-2010Foundation design code[S].Shanghai:Shanghai Building Materials Market Management Center,2010(in Chinese))
[2]刘金砺,秋仁东,邱明兵,等.不同条件下桩侧阻力端阻力性状及侧阻力分布概化与应用[J].岩土工程学报,2014,36(11):1953-1970(Liu Jinli,Qiu Rendong,Qiu Mingbing,et al.Behaviors of shaft resistance and tip resistance of piles under different conditions and conceptualization and application of distribution of shaft resistance[J].Chinese Journal of Geotechnical Engineering,2014,36(11):1953-1970(in Chinese))
[3]刘金砺,邱明兵,秋仁东,高文生.Mindlin解均化应力分层总和法计算群桩基础沉降[J].土木工程学报,2014,47(5):118-127(Liu Jinli,Qiu Mingbing,Qiu Rendong,et al.A layerwise summation method for settlement calculation of pile group based on the homogenized Mindlin stress[J].China Civil Engineering Journal,2014,47(5):118-127(in Chinese))
[4]JGJ 94-2008建筑桩基技术规范[S].北京:中国建筑工业出版社,2008(JGJ 94-2008 Technical code for building pile foundation[S].Beijing:China Architecture and Building Press,2008(in Chinese))
[5]刘金砺,迟铃泉.桩土变形计算模型和变刚度调平设计[J].岩土工程学报,2000,22(2):151-157(Liu Jinli,Chi Lingquan.The modified model of pile-soil deformation calculation and variable rigidity design method for balance settlement[J].Chinese Journal of Geotechnical Engineering,2000,22(2):151-157(in Chinese))
[6]王涛,刘金砺,王旭.基于桩侧阻概化模式的基桩均化附加应力系数研究[J].岩土工程学报,2018,40(4):665-672(Wang Tao,Liu Jinli,Wang Xu.Homogenized additional stress coefficient of foundation piles based on generalized mode of pile shaft resistance[J].Chinese Journal of Geotechnical Engineering,2018,40(4):665-672(in Chinese))
[7]Mindlin R D.Force at a point in the interior of a semiinfinite solid[J].Journal of Applied Physics,2004,7(5):195-202
[8]Geddes J D.Stresses in foundation soils due to vertical subsurface loading[J].Geotechnique,1966,16(3):231-255
[9]DGJ 08-11-2010地基基础设计规范[S].上海:上海市建筑建材业市场管理总站,2010(DGJ 08-11-2010Foundation design code[S].Shanghai:Shanghai Building Materials Market Management Center,2010(in Chinese))