碎石土土体性状对桩基水平承载能力的影响
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摘要
桩基作为一种广泛使用的基础形式,其在如地震荷载、风荷载下的水平承载力确定十分重要。桩基水平承载能力主要由桩身及土体性质控制,而土体性质中密实度和含石量是影响碎石土场地上桩基水平承载能力的主要因素。为明确碎石土场地土性对桩基水平承载能力的影响,在室内开展5组不同土体密实度和含石量下的水平场地单桩水平静载试验,以此模型试验数据计算所得的临界荷载、极限荷载、水平扩散角、计算宽度和水平抗力系数的比例系数m值等为指标评价土体密实度和含石量对桩基水平承载能力的影响。试验结果表明增大密实度和含石量对各指标均有提升效果,但相比之下,密实度对各项指标的提升效果均明显优于含石量。综合考量下,碎石土密实度和含石量的增大均对桩基水平承载力有提升作用,但土体密实度的提升作用更明显。故对水平承载力要求较高的碎石土上桩基工程的选址中,应优先选择密实度较大的场地。
The lateral loading capacity of various foundations are facing different requirements when they are applied to more and more fields. As the widespread usage of foundation forms,pile foundation plays an important role in various engineering. The two kinds of bearing capacity of pile foundation include vertical bearing capacity and lateral bearing capacity. Lateral capacity plays a crucial role in many situations in order to determine the stability under the seismic load and wind load specially. The lateral bearing capacity of pile foundation is mainly affected by pile and soil properties while the compactness and stone content of soil are the major factors to influence the lateral bearing capacity of the pile foundation on the gravel soil. This paper aims to clarify the influence of soil properties from the gravel soils on the lateral bearing capacity of pile foundations. It carries out 5 groups of indoor tests on static lateral loading test of single piles under different soil compactness and stone content. To achieve the expectation of the test,the relationship of piles' top displacement and lateral load is recorded. Their curves are plotted for the relationship with different compactness and stone content. Furthermore,critical load and ultimate load are found from these curves. As the load increases,the development of soil fissures surrounding the pile is recorded by taking photos and sketching in the progress of loading and writing explanations. The stress-strain process is divided into three parts according to the curve of piles' top displacement and lateral load and the development of soil fissure surrounding the pile. Lateral radial angle is obtained from the soil fissure angle surrounding the pile and is another important index to explain the lateral bearing capacity of pile foundation.According to the principle of horizontal diffusion,the effective calculating width in different soil properties is calculated using the lateral radial angle. Finally,the formulation of effective calculating width which provided by specification is adopted to calculate the proportional coefficient of lateral resistance coefficient-m value. It is proved that when the soil compactness is increased by 20%the critical and ultimate load growths are about 1. 5 KN and 1. 7 KN respectively,the horizontal diffusion angle growth is about 13° and the m value growth is about 120 MN/m4.When the soil stone content is increased by 20%critical and ultimate load growths are about 0. 6 KN and 0. 5 KN,respectively,the horizontal diffusion angle growth is about 3°,the m value growth is about 50 MN/m4. The experiments show that the increasing of compactness and stone content has an improvement on each index. But by contrast,the effect of compactness on various indexes is obviously better than that of stone content. Under comprehensive consideration,the increasing of compactness and stone content of gravel soil can enhance the lateral bearing capacity of pile foundation,but the effect of soil compactness is more obvious. Therefore,as for the site selection of pile foundation engineering on gravel soil which requires higher horizontal bearing capacity,the site with higher compactness should be preferentially selected.
The lateral loading capacity of various foundations are facing different requirements when they are applied to more and more fields. As the widespread usage of foundation forms,pile foundation plays an important role in various engineering. The two kinds of bearing capacity of pile foundation include vertical bearing capacity and lateral bearing capacity. Lateral capacity plays a crucial role in many situations in order to determine the stability under the seismic load and wind load specially. The lateral bearing capacity of pile foundation is mainly affected by pile and soil properties while the compactness and stone content of soil are the major factors to influence the lateral bearing capacity of the pile foundation on the gravel soil. This paper aims to clarify the influence of soil properties from the gravel soils on the lateral bearing capacity of pile foundations. It carries out 5 groups of indoor tests on static lateral loading test of single piles under different soil compactness and stone content. To achieve the expectation of the test,the relationship of piles' top displacement and lateral load is recorded. Their curves are plotted for the relationship with different compactness and stone content. Furthermore,critical load and ultimate load are found from these curves. As the load increases,the development of soil fissures surrounding the pile is recorded by taking photos and sketching in the progress of loading and writing explanations. The stress-strain process is divided into three parts according to the curve of piles' top displacement and lateral load and the development of soil fissure surrounding the pile. Lateral radial angle is obtained from the soil fissure angle surrounding the pile and is another important index to explain the lateral bearing capacity of pile foundation.According to the principle of horizontal diffusion,the effective calculating width in different soil properties is calculated using the lateral radial angle. Finally,the formulation of effective calculating width which provided by specification is adopted to calculate the proportional coefficient of lateral resistance coefficient-m value. It is proved that when the soil compactness is increased by 20%the critical and ultimate load growths are about 1. 5 KN and 1. 7 KN respectively,the horizontal diffusion angle growth is about 13° and the m value growth is about 120 MN/m4.When the soil stone content is increased by 20%critical and ultimate load growths are about 0. 6 KN and 0. 5 KN,respectively,the horizontal diffusion angle growth is about 3°,the m value growth is about 50 MN/m4. The experiments show that the increasing of compactness and stone content has an improvement on each index. But by contrast,the effect of compactness on various indexes is obviously better than that of stone content. Under comprehensive consideration,the increasing of compactness and stone content of gravel soil can enhance the lateral bearing capacity of pile foundation,but the effect of soil compactness is more obvious. Therefore,as for the site selection of pile foundation engineering on gravel soil which requires higher horizontal bearing capacity,the site with higher compactness should be preferentially selected.
引文
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Bonab M H.2013.Study of strain wedge parameters for laterally loaded piles[J].International Journal of Geomechanics,13(2):143-152.
Cao W P,Xia B,Zhao M,et al.2018.p-y curves of laterally loaded batter piles in sand and its application[J].Chinese Journal of Rock Mechanics and Engineering,37(3):743-753.
CCCC Highway Consultants CO.,Ltd.2007.Code for design of ground base and foundation of highway bridges and culverts(JTGD63-2007)[S].Beijing:China Communications Press.
Chen L J,Zheng J,Yu Q F.2017.Analysis of design elements of incline load short rigid pile in slope crest zone[J].Journal of Engineering Geology,25(6):1593-1602.
Chen J B.2018.The Distribution of sustaining strength with depth innersoil for slope topographic[D].Chengdu:Chengdu University of Technology.
Guo Q G.2002.Engineering characteristics and application of coarsegrained soil[M].Henan:The Yellow River Water Conservancy Press.
Jiang C G.2010.Doctrine and practice of pile foundation[M].Beijing:Chemical Industry Press.
Li D F,Zhao X Y,Hu X W,et al.2018.Influence of sectional dimension of stabilizing piles on soil arching characteristics.[J].Journal of Engineering Geology,26(2):484-493.
Li Q W,Li H N.2008.Study on dynamic stability of transmission tower[J].Journal of Disaster Prevention and Mitigation Engineering,28(2):202-207.
Liu B.2017.The study on the values of different properties of the gravel soil foundation coefficient m value by model test[D].Chengdu:Chengdu University of Technology.
Otani J,Pham K D,Sano J.2006.Investigation of failure patterns in sand due to laterally loaded pile using X-ray CT[J].Soils&Foundations,46(4):529-535.
Rathod D,Muthukkumaran K,Sitharam T G.2018.Effect of slope on p-y curves for laterally loaded piles in soft clay[J].Geotechnical&Geological Engineering,36:1509-1524.
The Professional Standards Compilation Group of People's Republic of China.1999.Standard for soil test method(GBT50123-1999)[S].Beijing:China Planning Press.
The Professional Standards Compilation Group of People's Republic of China.2001.Code for investigation of geotechnical engineering(GB50021-2001)[S].Beijing:China Planning Press.
The Professional Standards Compilation Group of People's Republic of China.2008.Technical code for building pile foundations(JGJ94-2008)[S].Beijing:China Architecture&Building Press.
The Professional Standards Compilation Group of People's Republic of China.2011.Code for design of concrete structures(GB50010-2010)[S].Beijing:China Architecture&Building Press.
Wang Y,Lin J,Chen J J,et al.2005.Field test for the behavior of prestressed pipe piles in soft subsoil under lateral load[J].Rock and Soil Mechanics,26(S1):39-42.
Wu F,Shi B L,Zhuo Y.2009.Nonlinear m method for piles under lateral load[J].Chinese Journal of Geotechnical Engineering,31(9):1398-1401.
Wu F F,Cao P,Wang L H.2007.Similarity theory and its application in simulation test[J].Mining Technology,7(4):64-65,78.
Zhang H M.2017.Study on horizontal bearing capacity of pile foundation in soft soil foundation[J].Traffic Science and Technology in Shandong,(5):52-54,60.
Zhang J M.2001.Effect of large horizontal pos-liquefaction deformation of level ground on pile foundation[J].Journal of Building Structures,22(5):75-78.
Zhu Y,Zhu H H,Zhang W,et al.2017.Parametric analysis on factors influencing stability of slopes reinforced by anti-slide piles[J].Journal of Engineering Geology,25(3):833-840.
曹卫平,夏冰,赵敏,等.2018.砂土中水平受荷斜桩的p-y曲线及其应用[J].岩石力学与工程学报,37(3):743-753.
陈继彬.2018.碎石土斜坡土体水平抗力分布规律研究[J].工程地质学报,26(4):959-968.
陈林靖,郑俊,余其凤.2017.坡顶面复合荷载刚性短桩工程设计要素分析[J].工程地质学报,25(6):1593-1602.
郭庆国.2002.粗粒土的工程特性及应用[M].河南:黄河水利出版社.
姜晨光.2010.桩基工程理论与实践[M].北京:化学工业出版社.
李登峰,赵晓彦,胡卸文,等.2018.抗滑桩截面尺寸对土拱性状的影响[J].工程地质学报,26(2):484-493.
李庆伟,李宏男.2008.输电塔结构的动力稳定性研究[J].防灾减灾工程学报,28(2):202-207.
刘斌.2017.不同性状碎石土地基系数m值取值模型试验研究[D].成都:成都理工大学.
王钰,林军,陈锦剑,等.2005.软土地基中PHC管桩水平受荷性状的试验研究[J].岩土力学,26(S1):39-42.
吴锋,时蓓玲,卓杨.2009.水平受荷桩非线性m法研究[J].岩土工程学报,31(9):1398-1401.
仵锋锋,曹平,万琳辉.2007.相似理论及其在模拟试验中的应用[J].采矿技术,7(4):64-65,78.
张建民.2001.水平地基液化后大变形对桩基础的影响[J].建筑结构学报,22(5):75-78.
章海明.2017.软土地基桩基础水平承载影响研究[J].山东交通科技,(5):52-54,60.
中华人民共和国行业标准编写组.1999.土工试验方法(GBT50123-1999)[S].北京:中国计划出版社.
中华人民共和国行业标准编写组.2001.岩土工程勘察规范(GB50021-2001)[S].北京:中华计划出版社.
中华人民共和国行业标准编写组.2008.建筑桩基技术规范(JGJ94-2008)[S].北京:中国建筑工业出版社.
中华人民共和国行业标准编写组.2011.混凝土结构设计规范(GB50010-2010)[S].北京:中国建筑工业出版社出版.
中交公路规划设计院有限公司.2007.公路桥涵地基与基础设计规范(JTGD63-2007)[S].北京:人民交通出版社.
朱泳,朱鸿鹄,张巍,等.2017.抗滑桩加固边坡稳定性影响因素的参数分析[J].工程地质学报,25(3):833-840.
Bonab M H.2013.Study of strain wedge parameters for laterally loaded piles[J].International Journal of Geomechanics,13(2):143-152.
Cao W P,Xia B,Zhao M,et al.2018.p-y curves of laterally loaded batter piles in sand and its application[J].Chinese Journal of Rock Mechanics and Engineering,37(3):743-753.
CCCC Highway Consultants CO.,Ltd.2007.Code for design of ground base and foundation of highway bridges and culverts(JTGD63-2007)[S].Beijing:China Communications Press.
Chen L J,Zheng J,Yu Q F.2017.Analysis of design elements of incline load short rigid pile in slope crest zone[J].Journal of Engineering Geology,25(6):1593-1602.
Chen J B.2018.The Distribution of sustaining strength with depth innersoil for slope topographic[D].Chengdu:Chengdu University of Technology.
Guo Q G.2002.Engineering characteristics and application of coarsegrained soil[M].Henan:The Yellow River Water Conservancy Press.
Jiang C G.2010.Doctrine and practice of pile foundation[M].Beijing:Chemical Industry Press.
Li D F,Zhao X Y,Hu X W,et al.2018.Influence of sectional dimension of stabilizing piles on soil arching characteristics.[J].Journal of Engineering Geology,26(2):484-493.
Li Q W,Li H N.2008.Study on dynamic stability of transmission tower[J].Journal of Disaster Prevention and Mitigation Engineering,28(2):202-207.
Liu B.2017.The study on the values of different properties of the gravel soil foundation coefficient m value by model test[D].Chengdu:Chengdu University of Technology.
Otani J,Pham K D,Sano J.2006.Investigation of failure patterns in sand due to laterally loaded pile using X-ray CT[J].Soils&Foundations,46(4):529-535.
Rathod D,Muthukkumaran K,Sitharam T G.2018.Effect of slope on p-y curves for laterally loaded piles in soft clay[J].Geotechnical&Geological Engineering,36:1509-1524.
The Professional Standards Compilation Group of People's Republic of China.1999.Standard for soil test method(GBT50123-1999)[S].Beijing:China Planning Press.
The Professional Standards Compilation Group of People's Republic of China.2001.Code for investigation of geotechnical engineering(GB50021-2001)[S].Beijing:China Planning Press.
The Professional Standards Compilation Group of People's Republic of China.2008.Technical code for building pile foundations(JGJ94-2008)[S].Beijing:China Architecture&Building Press.
The Professional Standards Compilation Group of People's Republic of China.2011.Code for design of concrete structures(GB50010-2010)[S].Beijing:China Architecture&Building Press.
Wang Y,Lin J,Chen J J,et al.2005.Field test for the behavior of prestressed pipe piles in soft subsoil under lateral load[J].Rock and Soil Mechanics,26(S1):39-42.
Wu F,Shi B L,Zhuo Y.2009.Nonlinear m method for piles under lateral load[J].Chinese Journal of Geotechnical Engineering,31(9):1398-1401.
Wu F F,Cao P,Wang L H.2007.Similarity theory and its application in simulation test[J].Mining Technology,7(4):64-65,78.
Zhang H M.2017.Study on horizontal bearing capacity of pile foundation in soft soil foundation[J].Traffic Science and Technology in Shandong,(5):52-54,60.
Zhang J M.2001.Effect of large horizontal pos-liquefaction deformation of level ground on pile foundation[J].Journal of Building Structures,22(5):75-78.
Zhu Y,Zhu H H,Zhang W,et al.2017.Parametric analysis on factors influencing stability of slopes reinforced by anti-slide piles[J].Journal of Engineering Geology,25(3):833-840.
曹卫平,夏冰,赵敏,等.2018.砂土中水平受荷斜桩的p-y曲线及其应用[J].岩石力学与工程学报,37(3):743-753.
陈继彬.2018.碎石土斜坡土体水平抗力分布规律研究[J].工程地质学报,26(4):959-968.
陈林靖,郑俊,余其凤.2017.坡顶面复合荷载刚性短桩工程设计要素分析[J].工程地质学报,25(6):1593-1602.
郭庆国.2002.粗粒土的工程特性及应用[M].河南:黄河水利出版社.
姜晨光.2010.桩基工程理论与实践[M].北京:化学工业出版社.
李登峰,赵晓彦,胡卸文,等.2018.抗滑桩截面尺寸对土拱性状的影响[J].工程地质学报,26(2):484-493.
李庆伟,李宏男.2008.输电塔结构的动力稳定性研究[J].防灾减灾工程学报,28(2):202-207.
刘斌.2017.不同性状碎石土地基系数m值取值模型试验研究[D].成都:成都理工大学.
王钰,林军,陈锦剑,等.2005.软土地基中PHC管桩水平受荷性状的试验研究[J].岩土力学,26(S1):39-42.
吴锋,时蓓玲,卓杨.2009.水平受荷桩非线性m法研究[J].岩土工程学报,31(9):1398-1401.
仵锋锋,曹平,万琳辉.2007.相似理论及其在模拟试验中的应用[J].采矿技术,7(4):64-65,78.
张建民.2001.水平地基液化后大变形对桩基础的影响[J].建筑结构学报,22(5):75-78.
章海明.2017.软土地基桩基础水平承载影响研究[J].山东交通科技,(5):52-54,60.
中华人民共和国行业标准编写组.1999.土工试验方法(GBT50123-1999)[S].北京:中国计划出版社.
中华人民共和国行业标准编写组.2001.岩土工程勘察规范(GB50021-2001)[S].北京:中华计划出版社.
中华人民共和国行业标准编写组.2008.建筑桩基技术规范(JGJ94-2008)[S].北京:中国建筑工业出版社.
中华人民共和国行业标准编写组.2011.混凝土结构设计规范(GB50010-2010)[S].北京:中国建筑工业出版社出版.
中交公路规划设计院有限公司.2007.公路桥涵地基与基础设计规范(JTGD63-2007)[S].北京:人民交通出版社.
朱泳,朱鸿鹄,张巍,等.2017.抗滑桩加固边坡稳定性影响因素的参数分析[J].工程地质学报,25(3):833-840.