扩底桩横向受荷下不同破坏模式的承载性状
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摘要
根据扩底桩的横向加载模型试验,分析研究扩底桩基础在横向荷载作用下出现不同破坏模式时的受力承载性状。试验结果表明,扩底桩出现弯曲破坏形式的受力承载性状为:在横向荷载作用下,加载一侧桩身受拉,另一侧桩身受压,最大拉应力出现在桩身中上部位置。桩身土压力分布为两端小,中部大。扩大头可为桩身提供嵌固作用。扩底桩出现剪切破坏时的受力承载性状为:在横向荷载作用下,桩身上部两侧均为受拉,桩身中下部加载一侧受拉,另一侧受压。桩身土压力分布呈波浪形,出现两处峰值和两处近似零点,扩大头基本不提供嵌固作用。研究结果表明,在相同的横向荷载作用下,出现弯曲破坏的桩比出现剪切破坏的桩具有更大的延性,扩大头的嵌固作用发挥的更好,具有更高的承载性能。
According to the lateral loading model test of belled pile,the load bearing behavior of the pile foundation under lateral load in different failure modes was analyzed. The test results show that the bearing properties of the pile in the form of bending failure as follows: under the lateral load,load side of the pile is pulled,the other side of the pile is pressed,and the maximum tensile stress appears in the middle-upper part of the pile. The earth pressure distribution of pile body is small at both ends and is large in the middle. The enlarged head can provide the fixed effect for pile body. The load bearing properties of shear failure of belled pile as follows: under the same lateral load,both sides of the upper part of the pile body are pulled,the middle and lower part is pulled on load side and the other side is pressed. The distribution of soil pressure in pile body is wavy,and two peaks and two approximate zeros appear. The enlarged head does not provide the fixed effect for pile body. The results show that: under the same transverse load,the pile foundation which is under bending failure could increase the ductility of pile foundation,could make belled pile bottom to be more built in the ground firmly,and could allow pile to take more loading than the pile under shear failure.
According to the lateral loading model test of belled pile,the load bearing behavior of the pile foundation under lateral load in different failure modes was analyzed. The test results show that the bearing properties of the pile in the form of bending failure as follows: under the lateral load,load side of the pile is pulled,the other side of the pile is pressed,and the maximum tensile stress appears in the middle-upper part of the pile. The earth pressure distribution of pile body is small at both ends and is large in the middle. The enlarged head can provide the fixed effect for pile body. The load bearing properties of shear failure of belled pile as follows: under the same lateral load,both sides of the upper part of the pile body are pulled,the middle and lower part is pulled on load side and the other side is pressed. The distribution of soil pressure in pile body is wavy,and two peaks and two approximate zeros appear. The enlarged head does not provide the fixed effect for pile body. The results show that: under the same transverse load,the pile foundation which is under bending failure could increase the ductility of pile foundation,could make belled pile bottom to be more built in the ground firmly,and could allow pile to take more loading than the pile under shear failure.
引文
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[2]张荣祥,顾宝和,汪敏,等.大直径扩底桩承载力和沉降变形分析[J].工程勘察,1998(4):18-23.(Zhang Rongxiang,Gu Baohe,Wang Ming,et al.Analysis of bearing capacity and settlement of large diameter belled pile[J].Journal of Geotechnical Investigation&Surveying,1998(4):18-23.(in Chinese))
[3]方焘,刘新荣,耿大新,等.大直径变径桩竖向承载特性模型试验研究(Ⅰ)[J].岩土力学,2012,33(10):2947-2952.(Fang Tao,Liu Xinrong,Geng Daxin,et al.Model Testing Study of Vertical Bearing Behaviors for Large Diameter Pile with Variable Cross-section(I)[J].Rock and Soil Mechanics,2012,33(10):2947-2952.(in Chinese))
[4]孙洋波,朱光裕.软土地区恒载作用下单桩和群桩的抗拔试验分析[J].地下空间与工程学报,2010,6(1):75-79,188.(Sun Yangbo,Zhu Guangyu.Field Tests on Uplift Behavior of Bored Cast-in-place Single or Group Piles Under Constant Load in Soft Ground[J].Chinese Journal of Underground Space and Engineering,2010,6(1):75-79,188.(in Chinese))
[5]黄广龙,惠刚,梅国雄.钻孔扩底桩原型对比试验研究[J].岩石力学与工程学报,2006,25(9):1922-1926.(Huang Guangling,Hui Gang,Mei Guoxiong.Comparative experiment study on pedestal piles[J].Chinese Journal of Rock Mechanics and Engineering,2006,25(9):1922-1926.(in Chinese))
[6]胡庆红,张土桥,谢新宇.深厚软土中大直径灌注扩底桩受力性状试验研究[J].土木工程学报,2007,40(4):87-91.(Hu Qinghong,Zhang Tuqiao,Xie Xinyu.Experimental study on the bearing capacity of large diameter cast-in-place under-reamed pile in deep soft soils[J].China Civil Engineering Journal,2007,40(4):87-91.(in Chinese))
[7]高盟,高广运,顾宝和,等.一种大直径扩底桩的沉降计算实用方法[J],岩土工程学报,2012,34(8):1448-1453.(Gao Meng,Gao Guangyun,Gu Baohe,et al.Practical method for settlement calculation of largediameter belled piles[J].Chinese Journal of Geotechnical Engineering,2012,34(8):1448-1453.(in Chinese))
[8]刘新荣,方焘,耿大新,等.大直径变径桩横向承载特性模型试验[J].中国公路学报,2013,26(6):80-86,190.(Liu Xinrong,Fang Tao,Geng Daxin,et al.Model Test on Lateral Bearing Behaviors of Large Diameter Pile with Variable Cross Section[J].China Journal of Highway and Transport,2013,26(6):80-86,190.(in Chinese))
[9]任连伟,王俊林.大直径扩底桩水平承载性能影响因素分析[J].岩土工程学报,2011,33(增2):299-303.(Ren Lianwei,Wang Junlin.Factors for Horizontal bearing capacity of large-diameter belled piles[J].Chinese Journal of Geotechnical Engineering,2011,33(Supp.2):299-30.(in Chinese))
[10]王俊林.大直径扩底桩单桩水平载荷试验研究[D].郑州:郑州大学,2011.(Wang Junlin.Analysis and research on horizontal static load tests on single large diameter under-reamed pile[D].Zhengzhou:Zhengzhou University,2011.(in Chinese))
[11]王俊林,王复明,任连伟,等.大直径扩底桩单桩水平静载试验与数值模拟[J].岩土工程学报,2010,32(9):1046-1411.(Wang Junlin,Wang Fuming,Ren Lianwei,et al.Horizontal static load tests and numerical simulation of single large diameter under-reamed pile[J].Chinese Journal of Geotechnical Engineering,2010,32(9):1046-1411.(in Chinese))
[12]孔纲强,曹兆虎,周航,等.水平荷载下扩底楔形桩承载力特性透明土模型试验[J].土木工程学报,2015,48(5):83-89.(Kong Gangqiang,Cao Zhaohu,Zhou Hang,et al.Experimental study on lateral bearing capacity of enlarged wedge-shaped pile using transparent soil[J].China Civil Engineering Journal,2015,48(5):83-89.(in Chinese))
[13]文松霖.铅直、水平荷载作用下扩底桩的承载机理[J].长江科学院院报,2004,21(5):24-27,31.(Wen Sonlin.Resistance behaviors of pile with enlarged base under axial and lateral loads[J].Journal of Yangtze River Scientific Research Institute,2004,21(5):24-27,31.(in Chinese))
[14]张蕾,高广运.扩底桩深度效应及临界桩长分析[J].地下空间与工程学报,2013,9(1):48-54.(Zhang Lei,Gao Guangyun.Study on depth effect and critical pile length for belled pile[J].Chinese Journal of Underground Space and Engineering,2013,9(1):48-54.(in Chinese))
[15]周景星,李广信,虞石民,等.基础工程(第2版)[M].北京:清华大学出版社,2006.(Zhou Jingxing,Li Guangxin,Yu Shimin,et al.Foundation engineering(Second Version)[M].Beijing:Tsinghua University Press,2006.(in Chinese))