竖向受荷螺杆桩承载特性离散元数值模拟
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摘要
螺杆桩技术已经在多种类型工程中得到了应用,然而由于认识条件的局限和研究对象的复杂,其理论分析仍然落后于工程实践.采用基于离散单元法的颗粒流程序,建立了竖向受荷螺杆桩的数值分析模型,并利用已有试验结果对模型细观参数进行了标定,在此基础上分析了螺距、螺纹段长度和桩径等设计参数对螺杆桩承载特性的影响.研究结果表明:随着螺距的增加,螺杆桩极限承载力呈先增加后减小的发展特征,螺距为(1.0-1.33)D时,螺杆桩具有最佳的承载表现,不同螺距螺杆桩的螺纹段荷载分担比例最高而直杆段最小.螺杆桩极限承载力随着螺纹段长度的增加先线性增长,而后基本保持不变,建议合理的螺纹段长度一般不超过2/3L.桩径增加时,螺杆桩极限承载力呈近似线性快速增长.数值模拟结果可以为螺杆桩设计参数优化和承载力估算方法确定提供理论依据.
Half screw pile technique has been applied in many kinds of projects. However,due to the limitations of cognitive conditions and the complexity of research objects,the theoretical analysis is still lagging behind the engineering practice. The particle flow code based on discrete element method was used to establish the numeri-cal analysis models of vertically loaded half screw piles,the microscopic parameters of the models were verified by the existing experimental results. On this basis,the effects of the design parameters such as screw spacing,length of the threaded section and external diameter on the bearing characteristics of the half screw piles were analyzed. The research results show that the ultimate bearing capacity of the half screw pile reaches maximum and then decreases with the increase of screw spacing,the half screw pile has the best bearing performance where the screw spacing is(1.0-1.33)D,the load sharing ratio of the threaded section is the highest,while the straight section is the lowest.The ultimate bearing capacity of the half screw pile increases linearly with the increase of the length of the threaded section,and then basically remains unchanged,and it is suggested that the reasonable length of the threaded section is generally not more than 2/3 L. With the increase of external diameter,the ultimate bearing capacity of the half screw pile is approximately linear and increasing rapidly. The numerical simulation results can provide some theoretical references for optimizing the design parameters and establishing the bearing capacity estimation method of the half screw pile.
Half screw pile technique has been applied in many kinds of projects. However,due to the limitations of cognitive conditions and the complexity of research objects,the theoretical analysis is still lagging behind the engineering practice. The particle flow code based on discrete element method was used to establish the numeri-cal analysis models of vertically loaded half screw piles,the microscopic parameters of the models were verified by the existing experimental results. On this basis,the effects of the design parameters such as screw spacing,length of the threaded section and external diameter on the bearing characteristics of the half screw piles were analyzed. The research results show that the ultimate bearing capacity of the half screw pile reaches maximum and then decreases with the increase of screw spacing,the half screw pile has the best bearing performance where the screw spacing is(1.0-1.33)D,the load sharing ratio of the threaded section is the highest,while the straight section is the lowest.The ultimate bearing capacity of the half screw pile increases linearly with the increase of the length of the threaded section,and then basically remains unchanged,and it is suggested that the reasonable length of the threaded section is generally not more than 2/3 L. With the increase of external diameter,the ultimate bearing capacity of the half screw pile is approximately linear and increasing rapidly. The numerical simulation results can provide some theoretical references for optimizing the design parameters and establishing the bearing capacity estimation method of the half screw pile.
引文
[1]张璐.高铁螺杆群桩复合地基特征研究[D].哈尔滨:哈尔滨工业大学,2017.ZHANG L. Research on character of screw pile group composite foundation used in high-speed railway[D]. Harbin:Harbin Institute of Technology,2017.(In Chinese)
[2]谭方,吴帅.泥岩地基螺杆桩竖向承载性能试验分析[J].土工基础,2013,27(1):69-71.TAN F,WU S.Test analysis on the bearing behavior of halfscrewed filing pile in mudstone foundation[J].Soil Engineering and Foundation,2013,27(1):69—71.(In Chinese)
[3]左宏亮,金宁政,许成云.黏性土地区螺杆灌注桩竖向承载力静载试验[J].沈阳建筑大学学报(自然科学版),2016,32(2):225-231.ZUO H L,JIN N Z,XU C Y.Experiment on vertical bearing capacity of screw grout pile in cohesive area[J]. Journal of Shenyang Jianzhu University(Natural Science),2016,32(2):225—231.(In Chinese)
[4]陈亚东,王安汀,蔡江东,等.竖向受荷螺杆桩承载变形特性模型试验[J].施工技术,2017,46(14):116-119.CHEN Y D,WANG A T,CAI J D,et al.Experimental study on bearing and deformation behavior of half-screw pile under vertical load[J].Construction Technology,2017,46(14):116—119.(In Chinese)
[5]刘剑雄,高妍妍,陈亚东.双曲线函数模型预测螺杆桩极限承载力[J].建筑技术,2016,47(5):424-427.LIU J X,GAO Y Y,CHEN Y D.Forecasting ultimate bearing capacity of half-screwed pile by hyperbolic function model[J].Architecture Technology,2016,47(5):424—427.(In Chinese)
[6] LIU Z,GUO G,LUO L,et al.Comparative research on mechanical behaviors between SDS piles and HS piles[C]//Proceedings of the Tunneling and Underground Construction,Shanghai,2014:205—215.
[7] FU Z,CHEN S,LIU S.Discrete element simulations of shallow plate-load tests[J]. International Journal of Geomechanics,2016,16(3):04015077.
[8] CUI Y,NOURI A,CHAN D,et al.A new approach to DEM simulation of sand production[J].Journal of Petroleum Science&Engineering,2016,147:56—67.
[9] ZHOU W,YANG L,MA G,et al.DEM modeling of shear bands in crushable and irregularly shaped granular materials[J].Granular Matter.,2017,19(2):25.
[10]WANG J F,ZHAO B D.Discrete-continuum analysis of monotonic pile penetration in crushable sands[J].Canadian Geotechnical Journal,2014,51(10):1095—1110.
[11]GU M X,HAN J,ZHAO M H. Three-dimensional discrete-element method analysis of stresses and deformations of a single geogridencased stone column[J].International Journal of Geomechanics,2017,17(9):04017070.
[12]LOBO-GUERRERO S,VALLEJO L E.Influence of pile shape and pile interaction on the crushable behavior of granular materials around driven piles:DEM analyses[J].Granular Matter.,2007,9(3/4):241—250.
[13] JIANG M,DAI Y,LIANG C,et al.Investigating mechanism of inclined CPT in granular ground using DEM[J].Granular Matter,2014,16(5):785—796.
[14]ZHANG L,THORNTON C. A numerical examination of the direct shear test[J].Geotechnique,2007,57(4):343—354.
[15]张坤勇,李威,罗兴军,等.基于PFC2D的砂土原生各向异性微观机理数值试验[J].岩土工程学报,2017,39(3):518-524.ZHANG K Y,LI W,LUO X J,et al.Numerical experiments of microscopic mechanism of inherent anisotropy for sand based on PFC2D[J].Chinese Journal of Geotechnical Engineering,2017,39(3):518—524.(In Chinese)
[16]陈亚东,王旭东,佘跃心,等.竖向受荷PCC桩宏细观工作性状研究[J].岩石力学与工程学报,2015,34(7):1503—1510.CHEN Y D,WANG X D,SHE Y X,et al.Macroscopic and mesoscopic working performance of PCC pile subjected to vertical load[J]. Chinese Journal of Rock Mechanics and Engineering,2015,34(7):1503—1510.(In Chinese)
[17] MOHAJERANI A,BOSNJAK D,BROMWICH D. Analysis and design methods of screw piles:A review[J]. Soils and Foundations,2016,56(1):115—128.
[18] SAKR M. Performance of helical piles in oil sand[J].Canadian Geotechnical Journal,2009,46(9):1046—1061.
[2]谭方,吴帅.泥岩地基螺杆桩竖向承载性能试验分析[J].土工基础,2013,27(1):69-71.TAN F,WU S.Test analysis on the bearing behavior of halfscrewed filing pile in mudstone foundation[J].Soil Engineering and Foundation,2013,27(1):69—71.(In Chinese)
[3]左宏亮,金宁政,许成云.黏性土地区螺杆灌注桩竖向承载力静载试验[J].沈阳建筑大学学报(自然科学版),2016,32(2):225-231.ZUO H L,JIN N Z,XU C Y.Experiment on vertical bearing capacity of screw grout pile in cohesive area[J]. Journal of Shenyang Jianzhu University(Natural Science),2016,32(2):225—231.(In Chinese)
[4]陈亚东,王安汀,蔡江东,等.竖向受荷螺杆桩承载变形特性模型试验[J].施工技术,2017,46(14):116-119.CHEN Y D,WANG A T,CAI J D,et al.Experimental study on bearing and deformation behavior of half-screw pile under vertical load[J].Construction Technology,2017,46(14):116—119.(In Chinese)
[5]刘剑雄,高妍妍,陈亚东.双曲线函数模型预测螺杆桩极限承载力[J].建筑技术,2016,47(5):424-427.LIU J X,GAO Y Y,CHEN Y D.Forecasting ultimate bearing capacity of half-screwed pile by hyperbolic function model[J].Architecture Technology,2016,47(5):424—427.(In Chinese)
[6] LIU Z,GUO G,LUO L,et al.Comparative research on mechanical behaviors between SDS piles and HS piles[C]//Proceedings of the Tunneling and Underground Construction,Shanghai,2014:205—215.
[7] FU Z,CHEN S,LIU S.Discrete element simulations of shallow plate-load tests[J]. International Journal of Geomechanics,2016,16(3):04015077.
[8] CUI Y,NOURI A,CHAN D,et al.A new approach to DEM simulation of sand production[J].Journal of Petroleum Science&Engineering,2016,147:56—67.
[9] ZHOU W,YANG L,MA G,et al.DEM modeling of shear bands in crushable and irregularly shaped granular materials[J].Granular Matter.,2017,19(2):25.
[10]WANG J F,ZHAO B D.Discrete-continuum analysis of monotonic pile penetration in crushable sands[J].Canadian Geotechnical Journal,2014,51(10):1095—1110.
[11]GU M X,HAN J,ZHAO M H. Three-dimensional discrete-element method analysis of stresses and deformations of a single geogridencased stone column[J].International Journal of Geomechanics,2017,17(9):04017070.
[12]LOBO-GUERRERO S,VALLEJO L E.Influence of pile shape and pile interaction on the crushable behavior of granular materials around driven piles:DEM analyses[J].Granular Matter.,2007,9(3/4):241—250.
[13] JIANG M,DAI Y,LIANG C,et al.Investigating mechanism of inclined CPT in granular ground using DEM[J].Granular Matter,2014,16(5):785—796.
[14]ZHANG L,THORNTON C. A numerical examination of the direct shear test[J].Geotechnique,2007,57(4):343—354.
[15]张坤勇,李威,罗兴军,等.基于PFC2D的砂土原生各向异性微观机理数值试验[J].岩土工程学报,2017,39(3):518-524.ZHANG K Y,LI W,LUO X J,et al.Numerical experiments of microscopic mechanism of inherent anisotropy for sand based on PFC2D[J].Chinese Journal of Geotechnical Engineering,2017,39(3):518—524.(In Chinese)
[16]陈亚东,王旭东,佘跃心,等.竖向受荷PCC桩宏细观工作性状研究[J].岩石力学与工程学报,2015,34(7):1503—1510.CHEN Y D,WANG X D,SHE Y X,et al.Macroscopic and mesoscopic working performance of PCC pile subjected to vertical load[J]. Chinese Journal of Rock Mechanics and Engineering,2015,34(7):1503—1510.(In Chinese)
[17] MOHAJERANI A,BOSNJAK D,BROMWICH D. Analysis and design methods of screw piles:A review[J]. Soils and Foundations,2016,56(1):115—128.
[18] SAKR M. Performance of helical piles in oil sand[J].Canadian Geotechnical Journal,2009,46(9):1046—1061.