削减桩基负摩阻力的室内模拟试验
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摘要
为探明桩基混凝土不同涂料对桩基负摩阻力的削减效果,通过大型剪切试验,以塑限18%的黏性土为试验土,着重研究了试验土含水率变化以及桩基混凝土侧面不同涂料对桩基负摩阻力的影响。结果表明,当黏性土含水率略大于塑限时,桩基负摩阻力的削减效果较好,此时在混凝土表面涂石蜡机油混合物、聚合物纳米材料或者油漆产生的削减效果基本一致;当黏性土含水率与塑限含水率相差较大时,采用石蜡机油混合物作为桩侧混凝土涂料对于桩基负摩阻力的削减效果最佳;可通过不同方式对中性点位置进行确定并采用不同适用条件下涂料对桩基负摩阻力进行削减。
In order to find out the effects of different coatings on the reduction of negative skin friction, the cohesive soil with a plastic limit of 18% as the test soil is studied based on the large shear tests. The influences of the moisture content and different coatings on the negative skin friction are emphatically studied. The results show that when the moisture content of the cohesive soil is slightly larger than that of the plastic limit, the reduction effects of negative skin friction are better, and the reduction effects of paraffin oil mixture, polymer nanomaterial or paint on concrete surface are basically the same. When the moisture content of cohesive soil differs greatly from that of the plastic limit, using the paraffin oil mixture as the pile side concrete coating has the best effects on the reduction of negative skin friction. The position of neutral point can be determined by different methods, and the negative skin friction of piles can be reduced by different applicable conditions.
In order to find out the effects of different coatings on the reduction of negative skin friction, the cohesive soil with a plastic limit of 18% as the test soil is studied based on the large shear tests. The influences of the moisture content and different coatings on the negative skin friction are emphatically studied. The results show that when the moisture content of the cohesive soil is slightly larger than that of the plastic limit, the reduction effects of negative skin friction are better, and the reduction effects of paraffin oil mixture, polymer nanomaterial or paint on concrete surface are basically the same. When the moisture content of cohesive soil differs greatly from that of the plastic limit, using the paraffin oil mixture as the pile side concrete coating has the best effects on the reduction of negative skin friction. The position of neutral point can be determined by different methods, and the negative skin friction of piles can be reduced by different applicable conditions.
引文
[1]TERZAGHI K,PECK R B,MESRI G.Soil mechanics in engineering practice[J].Soil Science,2014,68(5):149-150.
[2]冯忠居.基础工程[M].北京:人民交通出版社,2001.(FENG Zhong-ju.Foundation engineering[M].Beijing:China Communications Press,2001.(in Chinese))
[3]聂如松,冷伍明.负摩阻力作用下的单桩竖向承载性状[J].中南大学学报(自然科学版),2013,44(4):1539-1544.(NIE Ru-song,LENG WU-ming.Vertical bearing behavior of single pile subject to negative skin friction[J].Journal of Central South University(Science and Technology),2013,44(4):1539-1544.(in Chinese))
[4]陈显新,徐新跃.桩负摩阻力的若干问题[J].岩石力学与工程学报,2004,23(增刊1):4615-4618.(CHEN Xian-xin,XU Xin-yue.Several issues about negative skin friction of piles[J].Chinese Journal of Rock Mechanics and Engineering,2004,23(S1):4615-4618.(in Chinese))
[5]杨庆,孔纲强,郑鹏一,等.堆载条件下单桩负摩阻力模型试验研究[J].岩土力学,2008,29(10):2805-2810.(YANG Qin,KONG Gang-qiang,ZHEN Peng-yi,et al.Model test study of negative skin friction for single pile under surface load[J].Rock and Soil Mechanics,2008,29(10):2805-2810.(in Chinese))
[6]马学宁,付江,王军,等.不同堆载形式对群桩负摩阻力的影响[J].岩土力学,2018,39(10):3531-3538.(MAXue-ning,FU Jiang,WANG Jun,et al.Effect of different surcharge loading forms on negative skin friction of pile groups[J].Rock and Soil Mechanics,2018,39(10):3531-3538.(in Chinese))
[7]HUANG T,GONG W,DAI G.Model tests on characteristics of pile foundation negative skin friction under different distributions of surcharge load[J].Journal of Southeast University,2015.
[8]XING H,LIU L.Field tests on influencing factors of negative skin friction for pile foundations in collapsible loess regions[J].International Journal of Civil Engineering,2018(2):1-10.
[9]SUN J J,WANG L M,HUANG X F.A study on the position of maximum negative skin friction on piles in collapsing loess ground[J].Journal of Seismology,2003,23(4):20-25.
[10]曹卫平,赵敏.黄土地基中人工挖孔扩底灌注桩负摩阻力试验研究[J].岩石力学与工程学报,2012,31(增刊1):3167-3173.(CAO Wei-ping,ZHAO Min.Experimental study of negative skin friction for man-made cast in-situ belled piles in loess soil foundation[J].Chinese Journal of Rock Mechanics and Engineering,2012,31(S1):3167-3173.(in Chinese))
[11]唐丽云,王鑫,杨更社,等.大气温度升高下冻土桩负摩阻力试验研究[J].地下空间与工程学报,2018,14(6):1527-1535.(TANG Li-yun,WANG Xin,YANG Geng-she,et al.Experimental study on negative friction resistance of pile in frozen soil under raising atmospheric temperature[J].Chinese Journal of Underground Space and Engineering,2018,14(6):1527-1535.(in Chinese))
[12]FELLENIUS B H.Down-drag on piles in clay due to negative skin friction[J].Canadian Geotechnical Journal,1972,9(4):323-337.
[13]MASHHOUR I,HANNA A.Drag load on end-bearing piles in collapsible soil due to inundation[J].Canadian Geotechnical Journal,2016,53(12):2030-2038.
[14]TAKAHASHI K,KATAYAMA T,SOUND S.Positive and negative skin friction on a pile in soft clayed ground at haneda[C]//GEO-COAST,Yokohama.1991(3/4/5/6):6-13.
[15]TAWFIQ K S,CALIENDO J A.Bitumen coating versus plastic sheeting for reducing negative skin friction[J].Journal of Materials in Civil Engineering,1995,7(1):69-81.
[16]FELLENIUS B H.Reducing negative skin friction with bitumen slip layers[J].Journal of Geotechnical&Geoenvironmental Engineering,1975,101(4):412-414.
[17]GB/T50123-1999土工试验方法标准[S].1999.(GB/T50123-1999 Standard for soil test method[S].1999.(in Chinese))
[18]JTG94-2008建筑桩基技术规范[S].2008.(JTG94-2008Technical code for building pile foundations[S].2008.(in Chinese))
[2]冯忠居.基础工程[M].北京:人民交通出版社,2001.(FENG Zhong-ju.Foundation engineering[M].Beijing:China Communications Press,2001.(in Chinese))
[3]聂如松,冷伍明.负摩阻力作用下的单桩竖向承载性状[J].中南大学学报(自然科学版),2013,44(4):1539-1544.(NIE Ru-song,LENG WU-ming.Vertical bearing behavior of single pile subject to negative skin friction[J].Journal of Central South University(Science and Technology),2013,44(4):1539-1544.(in Chinese))
[4]陈显新,徐新跃.桩负摩阻力的若干问题[J].岩石力学与工程学报,2004,23(增刊1):4615-4618.(CHEN Xian-xin,XU Xin-yue.Several issues about negative skin friction of piles[J].Chinese Journal of Rock Mechanics and Engineering,2004,23(S1):4615-4618.(in Chinese))
[5]杨庆,孔纲强,郑鹏一,等.堆载条件下单桩负摩阻力模型试验研究[J].岩土力学,2008,29(10):2805-2810.(YANG Qin,KONG Gang-qiang,ZHEN Peng-yi,et al.Model test study of negative skin friction for single pile under surface load[J].Rock and Soil Mechanics,2008,29(10):2805-2810.(in Chinese))
[6]马学宁,付江,王军,等.不同堆载形式对群桩负摩阻力的影响[J].岩土力学,2018,39(10):3531-3538.(MAXue-ning,FU Jiang,WANG Jun,et al.Effect of different surcharge loading forms on negative skin friction of pile groups[J].Rock and Soil Mechanics,2018,39(10):3531-3538.(in Chinese))
[7]HUANG T,GONG W,DAI G.Model tests on characteristics of pile foundation negative skin friction under different distributions of surcharge load[J].Journal of Southeast University,2015.
[8]XING H,LIU L.Field tests on influencing factors of negative skin friction for pile foundations in collapsible loess regions[J].International Journal of Civil Engineering,2018(2):1-10.
[9]SUN J J,WANG L M,HUANG X F.A study on the position of maximum negative skin friction on piles in collapsing loess ground[J].Journal of Seismology,2003,23(4):20-25.
[10]曹卫平,赵敏.黄土地基中人工挖孔扩底灌注桩负摩阻力试验研究[J].岩石力学与工程学报,2012,31(增刊1):3167-3173.(CAO Wei-ping,ZHAO Min.Experimental study of negative skin friction for man-made cast in-situ belled piles in loess soil foundation[J].Chinese Journal of Rock Mechanics and Engineering,2012,31(S1):3167-3173.(in Chinese))
[11]唐丽云,王鑫,杨更社,等.大气温度升高下冻土桩负摩阻力试验研究[J].地下空间与工程学报,2018,14(6):1527-1535.(TANG Li-yun,WANG Xin,YANG Geng-she,et al.Experimental study on negative friction resistance of pile in frozen soil under raising atmospheric temperature[J].Chinese Journal of Underground Space and Engineering,2018,14(6):1527-1535.(in Chinese))
[12]FELLENIUS B H.Down-drag on piles in clay due to negative skin friction[J].Canadian Geotechnical Journal,1972,9(4):323-337.
[13]MASHHOUR I,HANNA A.Drag load on end-bearing piles in collapsible soil due to inundation[J].Canadian Geotechnical Journal,2016,53(12):2030-2038.
[14]TAKAHASHI K,KATAYAMA T,SOUND S.Positive and negative skin friction on a pile in soft clayed ground at haneda[C]//GEO-COAST,Yokohama.1991(3/4/5/6):6-13.
[15]TAWFIQ K S,CALIENDO J A.Bitumen coating versus plastic sheeting for reducing negative skin friction[J].Journal of Materials in Civil Engineering,1995,7(1):69-81.
[16]FELLENIUS B H.Reducing negative skin friction with bitumen slip layers[J].Journal of Geotechnical&Geoenvironmental Engineering,1975,101(4):412-414.
[17]GB/T50123-1999土工试验方法标准[S].1999.(GB/T50123-1999 Standard for soil test method[S].1999.(in Chinese))
[18]JTG94-2008建筑桩基技术规范[S].2008.(JTG94-2008Technical code for building pile foundations[S].2008.(in Chinese))