循环荷载下劲性微型桩单桩模型试验研究
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摘要
以1/7比例进行室内模型试验,采用荷载控制加载的拟静力试验方法,通过在桩顶施加侧向循环荷载,对劲性微型桩单桩的滞回曲线、骨架曲线和滞回特性进行研究,同时探讨了循环荷载下劲性微型桩的弯矩分布及破坏机制。研究表明,劲性微型桩在循环荷载作用下荷载-位移关系具有稳定的滞回环,且表现出刚度退化的特性;在上部土体范围内产生桩土脱开效应,滞回曲线发生捏拢现象;桩身弯矩主要集中在桩顶下17 d的范围内,最大弯矩位于桩顶下6 d附近。
The physical model tests of stiffened micropiles with similarity ratio of 1/7 are carried out.By using the pseudo-static test method in which the force control load and imposing load on the top of the micropile are used,the hysteretic curves,skeleton curves,the hysteretic characteristics,the bending moment and the failure mechanism of single stiffened micropile under circulating load are obtained.The tests results show that,the load-displacement lelation has the stable hysteresis loop and the characteristics of the stiffness degradation;the separation effect between the micropile and soil happened in the upper soil under the lateral cyclic load;and the atrophy phenomenon is found in the hysteresis curve;the bending moment of micropile mainly concentrated within the scope where the distance below the top of the pile is about 17 times diameter of micropile;and the maximum bending moment is located below the top of the pile with the distance about 6 times diameter of micropile.
The physical model tests of stiffened micropiles with similarity ratio of 1/7 are carried out.By using the pseudo-static test method in which the force control load and imposing load on the top of the micropile are used,the hysteretic curves,skeleton curves,the hysteretic characteristics,the bending moment and the failure mechanism of single stiffened micropile under circulating load are obtained.The tests results show that,the load-displacement lelation has the stable hysteresis loop and the characteristics of the stiffness degradation;the separation effect between the micropile and soil happened in the upper soil under the lateral cyclic load;and the atrophy phenomenon is found in the hysteresis curve;the bending moment of micropile mainly concentrated within the scope where the distance below the top of the pile is about 17 times diameter of micropile;and the maximum bending moment is located below the top of the pile with the distance about 6 times diameter of micropile.
引文
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[2]韩英才,NOVAK M.水平荷载作用下单桩的动力分析[J].地震工程与工程振动.1989,9(2):97-106.HAN Ying-cai,NOVAK M.Dynamic analysis for a singlepile under horizontal loading[J].Earthquake En-gineering and Engineering Vibration.1989,9(2):97-106.
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[4]武思宇,宋二祥,刘华北,等.刚性桩复合地基抗震性能的振动台试验研究[J].岩土力学,2007,28(1):77-82.WU Si-yu,SONG Er-xiang,LIU Hua-bei,et al.Shakingtable test study on aseismic behavior of rigid pilecomposite foundation[J].Rock and Soil Mechanics,2007,28(1):77-82.
[5]黄小明,赵利平.水平循环荷载作用下桩-土相互工作机理的研究现状[J].湖南交通科技,2003,29(1):87-89.HUANG Xiao-ming,ZHAO Li-ping.Current situation onstudy of pile-soil interaction mechanism under the actionof horizontal load[J].Hunan Communication Scienceand Technology,2003,29(1):87-89.
[6]王娴明.建筑结构试验[M].北京:清华大学出版社,2004.
[7]金伟良,宋志刚.水平循环荷载作用下单桩动力特性的数值模拟[J].海洋工程,2003,21(1):13-18.JIN Wei-liang,SONG Zhi-gang.Numerical simulation ofpile dynamic characteristics under lateral recyclingload[J].The Ocean Engineering,2003,21(1):13-18.
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