桩长对单桩沉桩阻力和承载力特性影响的模型试验
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摘要
静压桩的应用越来越广泛,为明确桩长与沉桩和承载力特性之间的关系,基于室内模型试验,对砂土中不同桩长的模型桩沉桩全过程进行了分析研究。采用振弦式压力计、微型土压力盒和高精度位移计对沉桩时的压桩端阻力、卸载后的桩周土压力和桩体回弹量进行测量,揭示了桩长与单桩沉桩和承载力特性的关系。试验结果显示,利用端阻计有效测得沉桩过程中的压桩端阻力,在600 mm深度范围,压桩端阻力随沉桩深度和桩长的增大而近似线性增大的特性;微型界面土压力盒对桩周土压力的测量揭示了随桩长的增大卸载后的桩周土压力逐渐趋近于被动土压力;但在某一深度位置卸载后的桩周土压力随沉桩深度的增大而降低的变化规律。采用高精度位移计较准确测得卸载过程中的桩体回弹量,得到了桩体回弹主要发生在竖向与桩长有关;并且回弹量相对较小,约为桩长的0. 35%。此外,桩体加载过程中沉降随加载变化的速率与桩长相关,桩体的极限承载力随桩长增大而非线性增大。研究结果对于进一步明确桩长对沉桩特性和桩体极限承载力特性的影响机理具有重要工程意义。
The application of static pressure piles is more and more extensive. In order to clarify the relationship between pile length and pile bearing and bearing capacity characteristics,based on the indoor model test,the whole process of model pile sinking with different pile lengths in sand is analyzed. The vibrating wire pressure gauge,the micro earth pressure box and the high-precision displacement meter were used to measure the pile end resistance during pile sinking,the earth pressure around the pile after unloading and the rebound amount of the pile,revealing the pile length and the single pile sinking. The relationship between pile and bearing capacity characteristics was revealed. The test results show that the pile tip resistance of the pile is effectively measured by the end resistance meter,and the resistance of the end of the pile is related to the line shape of the pile depth,the pile depth in the depth range of 600 mm. The measurement of the soil pressure around the pile by the micro-interface earth pressure box reveals that the soil pressure around the pile after unloading gradually approaches the passive earth pressure with the increase of the pile length,but after unloading at a certain depth position,the variation of the earth pressure around the pile with the increase of the pile depth increases. The high-precision displacement meter is used to accurately measure the rebound amount of the pile during the unloading process. It is found that the rebound of the pile mainly occurs in the vertical direction and the length of the pile,and the rebound amount is relatively small,about 0. 35% of the pile length. In addition,the rate of settlement change with loading during the loading process of the pile is related to the length of the pile. The ultimate bearing capacity of the pile increases non linearly with the increase of the pile length. The research results have important engineering significance for further clarifying the influence of pile length on the characteristics of pile sinking and the ultimate bearing capacity of piles.
The application of static pressure piles is more and more extensive. In order to clarify the relationship between pile length and pile bearing and bearing capacity characteristics,based on the indoor model test,the whole process of model pile sinking with different pile lengths in sand is analyzed. The vibrating wire pressure gauge,the micro earth pressure box and the high-precision displacement meter were used to measure the pile end resistance during pile sinking,the earth pressure around the pile after unloading and the rebound amount of the pile,revealing the pile length and the single pile sinking. The relationship between pile and bearing capacity characteristics was revealed. The test results show that the pile tip resistance of the pile is effectively measured by the end resistance meter,and the resistance of the end of the pile is related to the line shape of the pile depth,the pile depth in the depth range of 600 mm. The measurement of the soil pressure around the pile by the micro-interface earth pressure box reveals that the soil pressure around the pile after unloading gradually approaches the passive earth pressure with the increase of the pile length,but after unloading at a certain depth position,the variation of the earth pressure around the pile with the increase of the pile depth increases. The high-precision displacement meter is used to accurately measure the rebound amount of the pile during the unloading process. It is found that the rebound of the pile mainly occurs in the vertical direction and the length of the pile,and the rebound amount is relatively small,about 0. 35% of the pile length. In addition,the rate of settlement change with loading during the loading process of the pile is related to the length of the pile. The ultimate bearing capacity of the pile increases non linearly with the increase of the pile length. The research results have important engineering significance for further clarifying the influence of pile length on the characteristics of pile sinking and the ultimate bearing capacity of piles.
引文
1郑华茂,陈淮,肖昭然.砂土中静压桩贯入过程中的桩周应力分析[J].水运工程,2017(3):138-144Zheng Huamao,Chen Huai,Xiao Zhaoran.Stress analysis of the jacked pile during the pressing process in sand[J].Port&Waterway Engineering,2017(3):138-144
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6尹新生,洪源.砂土中内击沉管桩贯入过程颗粒流模拟[J].吉林建筑大学学报,2015,32(2):25-27Yin Xinsheng,Hong Yuan.Particle flow simulation of the sand sinking pipe pile penetration[J].Journal of Jilin Jianzhu University,2015,32(2):25-27
7王浩,周健,邓志辉.砂土中桩端阻力随位移发挥的内在机理研究[J].岩土工程学报,2006(5):587-593Wang Hao,Zhou Jian,Deng Zhihui.Mobilization of toe resistance of piles with local displacement in sand[J].Chinese Journal of Geotechnical Engineering,2006(5):587-593
8曹兆虎,孔纲强,刘汉龙,等.基于透明土的管桩贯入特性模型试验研究[J].岩土工程学报,2014,36(8):1564-1568Cao Zhaohu,Kong Gangqiang,Liu Hanlong,et al.Model tests on pipe pile penetration by using transparent soils[J].Chinese Journal of Geotechnical Engineering,2014,36(8):1564-1568
9黄雨,柏炯,周国鸣,等.单向循环荷载作用下饱和砂土中单桩沉降模型试验研究[J].岩土工程学报,2009,31(9):1440-1444Huang Yu,Bai Jiong,Zhou Guoming,et al.Model tests on settlement of a single pile in saturated sand under unilateral cyclic loading[J].Chinese Journal of Geotechnical Engineering,2009,31(9):1440-1444
10皇甫明,王幼青,王梦恕.水平力对竖直桩沉降和承载力影响的研究[J].岩土工程学报,2003,25(4):511-513Huang Fuming,Wang Youqing,Wang Mengshu.Study of effects of lateral loads on the settlement and bearing capacity of pile[J].Chinese Journal of Geotechnical Engineering,2003,25(4):511-513
11 Meera R S,Shanker K,Basudhar P K.Flexural response of piles under liquefied soil conditions[J].Geotechnical and Geological Engineering,2007,25(4):409-422
12 Yu F,Yang Y F.Discussion of“termination criteria for Jacked pile construction and load transfer in weathered soils”by L M Zhang,CW W Ng,F Chan and H W Pang[J].Journal of Geotechnical and Geoenvironmental Engineering,2007,133(11):1477-1479
13 Lee J,Prezzi M,Salgado R.Experimental investigationof the combined load response of model piles driven in sand[J].Geotechnical Testing Journal,2011,34(6):1-15
14 Liaang F Y,Chen H B,Chen S L.Influences of axial load on the lateral response of single pile with integral equation method[J].International Journal for Numerical and Analytical Methods in Geomechanics,2012,36(16):1831-1845
15肖昭然,刘轶.静力沉桩的室内模型试验装置研发[J].岩土工程学报,2012,34(9):1695-1698Xiao Zhaoran,Liu Yi.Development of laboratory model test equipments for jacked piles[J].Chinese Journal of Geotechnical Engineering,2012,34(9):1695-1698
2蒋跃楠,黄广龙.砂土中静压桩的桩端作用效应分析[J].建筑科学,2016,32(11):74-82Jiang Yuenan,Huang Guanglong.Study on pile tip effect of jacked pile in sand[J].Building Science,2016,32(11):74-82
3蒋跃楠,黄广龙,分层土中的沉桩试验及分析[J].工程勘察,2017,45(4):1-6Jiang Yuenan,Huang Guanglong.Experiment and analysis of jacked pile in layered soil[J].Geotechnical Investigation&Surveying,2017,45(4):1-6
4周健,邓益兵,叶建忠,等.砂土中静压桩沉桩过程试验研究与颗粒流模拟[J].岩土工程学报,2009,31(4):501-507Zhou Jian,Deng Yibing,Ye Jianzhong,et al.Experimental and numerical analysis of jacked piles during installation in sand[J].Chinese Journal of Geotechnical Engineering,2009,31(4):501-507
5周健,郭建军,张昭,等.砂土中单桩静载室内模型试验及颗粒流数值模拟[J].岩土力学,2010,31(6):1763-1768Zhou Jian,Guo Jianjun,Zhang Zhao,et al.Model test of single pile static load in sands and numerical simulation using particle flow code[J].Rock and Soil Mechanics,2010,31(6):1763-1768
6尹新生,洪源.砂土中内击沉管桩贯入过程颗粒流模拟[J].吉林建筑大学学报,2015,32(2):25-27Yin Xinsheng,Hong Yuan.Particle flow simulation of the sand sinking pipe pile penetration[J].Journal of Jilin Jianzhu University,2015,32(2):25-27
7王浩,周健,邓志辉.砂土中桩端阻力随位移发挥的内在机理研究[J].岩土工程学报,2006(5):587-593Wang Hao,Zhou Jian,Deng Zhihui.Mobilization of toe resistance of piles with local displacement in sand[J].Chinese Journal of Geotechnical Engineering,2006(5):587-593
8曹兆虎,孔纲强,刘汉龙,等.基于透明土的管桩贯入特性模型试验研究[J].岩土工程学报,2014,36(8):1564-1568Cao Zhaohu,Kong Gangqiang,Liu Hanlong,et al.Model tests on pipe pile penetration by using transparent soils[J].Chinese Journal of Geotechnical Engineering,2014,36(8):1564-1568
9黄雨,柏炯,周国鸣,等.单向循环荷载作用下饱和砂土中单桩沉降模型试验研究[J].岩土工程学报,2009,31(9):1440-1444Huang Yu,Bai Jiong,Zhou Guoming,et al.Model tests on settlement of a single pile in saturated sand under unilateral cyclic loading[J].Chinese Journal of Geotechnical Engineering,2009,31(9):1440-1444
10皇甫明,王幼青,王梦恕.水平力对竖直桩沉降和承载力影响的研究[J].岩土工程学报,2003,25(4):511-513Huang Fuming,Wang Youqing,Wang Mengshu.Study of effects of lateral loads on the settlement and bearing capacity of pile[J].Chinese Journal of Geotechnical Engineering,2003,25(4):511-513
11 Meera R S,Shanker K,Basudhar P K.Flexural response of piles under liquefied soil conditions[J].Geotechnical and Geological Engineering,2007,25(4):409-422
12 Yu F,Yang Y F.Discussion of“termination criteria for Jacked pile construction and load transfer in weathered soils”by L M Zhang,CW W Ng,F Chan and H W Pang[J].Journal of Geotechnical and Geoenvironmental Engineering,2007,133(11):1477-1479
13 Lee J,Prezzi M,Salgado R.Experimental investigationof the combined load response of model piles driven in sand[J].Geotechnical Testing Journal,2011,34(6):1-15
14 Liaang F Y,Chen H B,Chen S L.Influences of axial load on the lateral response of single pile with integral equation method[J].International Journal for Numerical and Analytical Methods in Geomechanics,2012,36(16):1831-1845
15肖昭然,刘轶.静力沉桩的室内模型试验装置研发[J].岩土工程学报,2012,34(9):1695-1698Xiao Zhaoran,Liu Yi.Development of laboratory model test equipments for jacked piles[J].Chinese Journal of Geotechnical Engineering,2012,34(9):1695-1698