柔性半掏挖基础上拔承载力模型试验及计算理论
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摘要
根据柔性半掏挖基础具有良好抗拔性能,适用于原状土土性较好且地下水位较深的地质条件的特点,以土性参数、深径比及锥体扩展角为参数,设计并制作4组原状土新型基础试验模型,开展其上拔稳定承载力试验;试验得到新型基础在上拔荷载下分为弹性段、弹塑性非线性段、直线破坏段3个变形阶段,以及最终地面土体隆起开裂的破坏形态。同时,开展不同场地土性参数下新型基础上拔稳定承载力特性的非线性模拟分析,考察柔性半掏挖基础与传统基础上拔荷载–位移特性及传力机制的差异。最后,对比土重法和剪切法2种计算理论的差异,当新型掏挖基础的深径比较大时,采用土重法计算承载力比剪切法计算值大20%以上且趋于不安全;基于土体剪切法圆弧面滑动面假设的上拔承载力计算理论,验证了上拔承载力理论计算值与试验值及模拟值吻合良好。
According to the characteristics of good uplift resistance of flexible semi-excavated foundation,which is suitable for better undisturbed soil and deeper underground water level condition,the uplift bearing capacity of the new type of foundation was studied. Considering different soil properties,depth-diameter ratio and cone spreading angle of new foundation,4 sets of test models of undisturbed soil were designed and manufactured,and the uplift stable bearing capacity tests were carried out. Tests results show that deformation of the foundation due to the uplift load experiences three distinct stages such as linear,elastic-plastic and failure stages and that the foundation fails in the form of the upheaval of the ground soil. The nonlinear behavior of uplift stable bearing capacity of the new flexible semi-excavated foundation was simulated,and the difference of deformation characteristics and force transfer mechanisms of the new foundation and the traditional excavated foundation was analyzed. Comparisons between soil weight method and shear method were performed. It is shown that,under the condition of a large depth-diameter ratio,the bearing capacity calculated by the soil weight method is 20% larger than that obtained by the shear method and hence,the soil weight method is unsafe. The calculation theory of the uplift bearing capacity of the new foundation was proposed based on the hypothesis of soil arc sliding surface considering the shear method,and the theoretical method of the uplift bearing capacity of the foundation was verified by test and simulation results.
According to the characteristics of good uplift resistance of flexible semi-excavated foundation,which is suitable for better undisturbed soil and deeper underground water level condition,the uplift bearing capacity of the new type of foundation was studied. Considering different soil properties,depth-diameter ratio and cone spreading angle of new foundation,4 sets of test models of undisturbed soil were designed and manufactured,and the uplift stable bearing capacity tests were carried out. Tests results show that deformation of the foundation due to the uplift load experiences three distinct stages such as linear,elastic-plastic and failure stages and that the foundation fails in the form of the upheaval of the ground soil. The nonlinear behavior of uplift stable bearing capacity of the new flexible semi-excavated foundation was simulated,and the difference of deformation characteristics and force transfer mechanisms of the new foundation and the traditional excavated foundation was analyzed. Comparisons between soil weight method and shear method were performed. It is shown that,under the condition of a large depth-diameter ratio,the bearing capacity calculated by the soil weight method is 20% larger than that obtained by the shear method and hence,the soil weight method is unsafe. The calculation theory of the uplift bearing capacity of the new foundation was proposed based on the hypothesis of soil arc sliding surface considering the shear method,and the theoretical method of the uplift bearing capacity of the foundation was verified by test and simulation results.
引文
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[3]MEYERHOF G G,ADAMS J I.The ultimate uplift capacity of foundations[J].Canadian Geotechnical Journal,1968,5(4):225-244.
[4]ILAMPARUTHI K,DICKIN E A.Predictions of the uplift response of model belied piles in geogrid-cell-reinforced sand[J].Geotextiles and Geomembranes,2001,19(2):89-109.
[5]HONG W P,CHIM N.Prediction of uplift capacity of a micropile embedded in soil[J].KSCE Journal of Civil Engineering,2015,19(1):116-126.
[6]乾增珍,鲁先龙,丁士君.塔克拉玛干沙漠输电线塔装配式基础试验研究[J].岩土力学,2011,32(8):2 359-2 364.(QIAN Zengzhen,LU Xianlong,DING Shijun.Experimental study of assembly foundation for transmission line tower in Taklimakan desert[J].Rock and Soil Mechanics,2011,32(8):2 359-2 364.(in Chinese))
[7]张大长,蒋刚,林致添,等.装配式型钢基础抗压抗拔承载力的试验及计算[J].岩土力学,2009,30(7):2 096-2 100.(ZHANG Dachang,JIANG Gang,LIN Zhitian,et al.Experimental studies and calculating method for compression and uplift capacities of fabricated steel foundation[J].Rock and Soil Mechanics,2009,30(7):2 096-2 100.(in Chinese))
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[9]鲁先龙.《架空送电线路基础设计技术规定》中基础抗拔剪切法计算参数A1和A2的研究[J].电力建设,2009,30(1):12-17.(LUXianlong.Study on parameters A1 and A2 in anti-uplift shearing method in“Technical regulations on overhead line foundation design”[J].Electric Power Construction,2009,30(1):12-17.(in Chinese))
[10]赵怀宇,李占岭,魏蓬辉.全掏挖基础在戈壁滩地区输电线路中的应用[J].土工基础,2012,26(4):27-30.(ZHAO Huaiyu,LIZhanling,WEI Penghui.The application of bell ended piers for transmission lines in the Gobi desert[J].Soil Engineering and Foundation,2012,26(4):27-30.(in Chinese))
[11]崔强,童瑞铭,刘升奎,等.基础尺寸对碎石土地基扩底基础上拔承载力影响的现场试验研究[J].土木建筑与环境工程,2016,38(6):17-22.(CUI Qiang,TONG Ruimin,LIU Shengkui,et al.Experimental analysis of the influence of foundation size parameters on the uplift bearing capacity of the spread foundation in gravel soil[J].Journal of Civil Architectural and Environmental Engineering,2016,38(6):17-22.(in Chinese))
[12]郝冬雪,樊广森,姜春宝,等.输电线路掏挖基础的抗拔承载特性数值分析[J].水电能源科学,2012,30(8):151-154.(HAODongxue,FAN Guangsen,JIANG Chunbao,et al.Numerical analysis of uplift bearing capacity of excavated foundation for transmission towers[J].International Journal Hydroelectric Energy,2012,30(8):151-154.(in Chinese))
[13]谢芳,冯炳.一种山区输电线路装配式柔性半掏挖基础[P].中国:CN105297763A,2016-02-03.(XIE Fang,FENG Bing.Aflexible semi-excavated foundation for transmission lines in mountainous area[P].China:CN105297763A,2016-02-03.(in Chinese))
[14]中华人民共和国行业标准编写组.JGJ106-2014建筑基桩检测技术规范[S].北京:中国建筑工业出版社,2014.(The Professional Standards Compilation Group of the People′s Republic of China.JGJ106-2014.Technical code for testing of building foundation piles[S].Beijing:China Architecture and Building Press,2014.(in Chinese))
[15]鲁先龙,乾增珍,童瑞铭,等.戈壁碎石土地基原状土掏挖基础抗拔试验研究[J].土木建筑与环境工程,2012,34(4):24-30.(LUXianlong,QIAN Zengzhen,TONG Ruiming,et al.Field test analysis on belled pier foundations under tensile load in gravel Gobi[J].Journal of Civil Architectural and Environmental Engineering,2012,34(4):24-30.(in Chinese))
[16]庄茁.ABAQUS有限元软件6.4版入门指南[M].北京:清华大学出版社,2004:287-292.(ZHUANG Zhuo.Introduction to ABAQUS6.4 edition of finite element software[M].Beijing:Tsinghua University Press,2004:287-292.(in Chinese))
[17]王金昌,陈页开.ABAQUS在土木工程中的应用[M].杭州:浙江大学出版社,2006:10-20.(WANG Jinchang,CHEN Yekai.Application of ABAQUS in civil engineering[M].Hangzhou:Zhejiang University Press,2006:10-20.(in Chinese))
[18]侯明勋,葛修润.岩体初始地应力场分析方法研究[J].岩土力学,2007,28(8):1 626-1 630.(HOU Mingxun,GE Xiurun.Study on fitting analysis of initial stress field in rock masses[J].Rock and Soil Mechanics,2007,28(8):1 626-1 630.(in Chinese))
[19]代汝林,李忠芳,王姣.基于ABAQUS的初始地应力平衡方法研究[J].重庆工商大学学报:自然科学版,2012,29(9):76-81.(DAI Rulin,LI Zhongfang,WANG Jiao.Research on initial geo-stress balance method based on ABAQUS[J].Journal of Chongqing Technology and Business University:Natural Science,2012,29(9):76-81.(in Chinese))
[20]鲁先龙.基于不同土体滑动面形态的基础抗拔“剪切法”计算参数A1和A2的统一理论公式[J].电力建设,2012,33(12):6-10.(LUXianlong.Unified theoretical formula of parameters A1 and A2 for shearing method of foundation uplift calculation at different soil failure plane morphology[J].Electric Power Construction,2012,33(12):6-10.(in Chinese))
[21]中华人民共和国行业标准编写组.DL/T 5219-2014架空输电线路基础设计技术规程[S].北京:中国计划出版社,2014.(The Professional Standards Compilation Group of the People′s Republic of China.DL/T5219-2014 Technical code for design of foundation of overhead transmission line[S].Beijing:China Planning Press,2014.(in Chinese))
[22]PACHECO M P,DANZIGER F A B,PINTO C P.Design of shallow foundations under tensile loading for transmission line towers:An overview[J].Engineering Geology,2008,101(3/4):226-235.
[23]BRAJA M D.Shallow foundations bearing capacity and settlement[M].New York:Taylor and Francis Group,2009:291-316.
[2]BALLA A.The resistance to breaking out of mushroom foundations for pylons[C]//Proceedings of the Fifth International Conference on Soil Mechanics and Foundation Engineering.Paris,France:[s.n.],1961:569-576.
[3]MEYERHOF G G,ADAMS J I.The ultimate uplift capacity of foundations[J].Canadian Geotechnical Journal,1968,5(4):225-244.
[4]ILAMPARUTHI K,DICKIN E A.Predictions of the uplift response of model belied piles in geogrid-cell-reinforced sand[J].Geotextiles and Geomembranes,2001,19(2):89-109.
[5]HONG W P,CHIM N.Prediction of uplift capacity of a micropile embedded in soil[J].KSCE Journal of Civil Engineering,2015,19(1):116-126.
[6]乾增珍,鲁先龙,丁士君.塔克拉玛干沙漠输电线塔装配式基础试验研究[J].岩土力学,2011,32(8):2 359-2 364.(QIAN Zengzhen,LU Xianlong,DING Shijun.Experimental study of assembly foundation for transmission line tower in Taklimakan desert[J].Rock and Soil Mechanics,2011,32(8):2 359-2 364.(in Chinese))
[7]张大长,蒋刚,林致添,等.装配式型钢基础抗压抗拔承载力的试验及计算[J].岩土力学,2009,30(7):2 096-2 100.(ZHANG Dachang,JIANG Gang,LIN Zhitian,et al.Experimental studies and calculating method for compression and uplift capacities of fabricated steel foundation[J].Rock and Soil Mechanics,2009,30(7):2 096-2 100.(in Chinese))
[8]鲁先龙,程永锋,张宇.输电线路原状土基础抗拔极限承载力计算[J].电力建设,2006,27(10):28-32.(LU Xianlong,CHENGYongfeng,ZHANG Yu.Calculation on ultimate uplift bearing capacity of undisturbed soil foundation in transmission lines[J].Electric Power Construction,2006,27(10):28-32.(in Chinese))
[9]鲁先龙.《架空送电线路基础设计技术规定》中基础抗拔剪切法计算参数A1和A2的研究[J].电力建设,2009,30(1):12-17.(LUXianlong.Study on parameters A1 and A2 in anti-uplift shearing method in“Technical regulations on overhead line foundation design”[J].Electric Power Construction,2009,30(1):12-17.(in Chinese))
[10]赵怀宇,李占岭,魏蓬辉.全掏挖基础在戈壁滩地区输电线路中的应用[J].土工基础,2012,26(4):27-30.(ZHAO Huaiyu,LIZhanling,WEI Penghui.The application of bell ended piers for transmission lines in the Gobi desert[J].Soil Engineering and Foundation,2012,26(4):27-30.(in Chinese))
[11]崔强,童瑞铭,刘升奎,等.基础尺寸对碎石土地基扩底基础上拔承载力影响的现场试验研究[J].土木建筑与环境工程,2016,38(6):17-22.(CUI Qiang,TONG Ruimin,LIU Shengkui,et al.Experimental analysis of the influence of foundation size parameters on the uplift bearing capacity of the spread foundation in gravel soil[J].Journal of Civil Architectural and Environmental Engineering,2016,38(6):17-22.(in Chinese))
[12]郝冬雪,樊广森,姜春宝,等.输电线路掏挖基础的抗拔承载特性数值分析[J].水电能源科学,2012,30(8):151-154.(HAODongxue,FAN Guangsen,JIANG Chunbao,et al.Numerical analysis of uplift bearing capacity of excavated foundation for transmission towers[J].International Journal Hydroelectric Energy,2012,30(8):151-154.(in Chinese))
[13]谢芳,冯炳.一种山区输电线路装配式柔性半掏挖基础[P].中国:CN105297763A,2016-02-03.(XIE Fang,FENG Bing.Aflexible semi-excavated foundation for transmission lines in mountainous area[P].China:CN105297763A,2016-02-03.(in Chinese))
[14]中华人民共和国行业标准编写组.JGJ106-2014建筑基桩检测技术规范[S].北京:中国建筑工业出版社,2014.(The Professional Standards Compilation Group of the People′s Republic of China.JGJ106-2014.Technical code for testing of building foundation piles[S].Beijing:China Architecture and Building Press,2014.(in Chinese))
[15]鲁先龙,乾增珍,童瑞铭,等.戈壁碎石土地基原状土掏挖基础抗拔试验研究[J].土木建筑与环境工程,2012,34(4):24-30.(LUXianlong,QIAN Zengzhen,TONG Ruiming,et al.Field test analysis on belled pier foundations under tensile load in gravel Gobi[J].Journal of Civil Architectural and Environmental Engineering,2012,34(4):24-30.(in Chinese))
[16]庄茁.ABAQUS有限元软件6.4版入门指南[M].北京:清华大学出版社,2004:287-292.(ZHUANG Zhuo.Introduction to ABAQUS6.4 edition of finite element software[M].Beijing:Tsinghua University Press,2004:287-292.(in Chinese))
[17]王金昌,陈页开.ABAQUS在土木工程中的应用[M].杭州:浙江大学出版社,2006:10-20.(WANG Jinchang,CHEN Yekai.Application of ABAQUS in civil engineering[M].Hangzhou:Zhejiang University Press,2006:10-20.(in Chinese))
[18]侯明勋,葛修润.岩体初始地应力场分析方法研究[J].岩土力学,2007,28(8):1 626-1 630.(HOU Mingxun,GE Xiurun.Study on fitting analysis of initial stress field in rock masses[J].Rock and Soil Mechanics,2007,28(8):1 626-1 630.(in Chinese))
[19]代汝林,李忠芳,王姣.基于ABAQUS的初始地应力平衡方法研究[J].重庆工商大学学报:自然科学版,2012,29(9):76-81.(DAI Rulin,LI Zhongfang,WANG Jiao.Research on initial geo-stress balance method based on ABAQUS[J].Journal of Chongqing Technology and Business University:Natural Science,2012,29(9):76-81.(in Chinese))
[20]鲁先龙.基于不同土体滑动面形态的基础抗拔“剪切法”计算参数A1和A2的统一理论公式[J].电力建设,2012,33(12):6-10.(LUXianlong.Unified theoretical formula of parameters A1 and A2 for shearing method of foundation uplift calculation at different soil failure plane morphology[J].Electric Power Construction,2012,33(12):6-10.(in Chinese))
[21]中华人民共和国行业标准编写组.DL/T 5219-2014架空输电线路基础设计技术规程[S].北京:中国计划出版社,2014.(The Professional Standards Compilation Group of the People′s Republic of China.DL/T5219-2014 Technical code for design of foundation of overhead transmission line[S].Beijing:China Planning Press,2014.(in Chinese))
[22]PACHECO M P,DANZIGER F A B,PINTO C P.Design of shallow foundations under tensile loading for transmission line towers:An overview[J].Engineering Geology,2008,101(3/4):226-235.
[23]BRAJA M D.Shallow foundations bearing capacity and settlement[M].New York:Taylor and Francis Group,2009:291-316.