摘要
以柱形孔扩张模型模拟沉桩过程,推导出考虑速度因素时桩周土体的位移、应力解析解。以弹塑性交界面处单元体的运动情况作为参考标准,将区域内任何一点的应力、位移描述成塑性区半径和扩张后土体单元距孔心的距离函数。采用小变形理论求解出r处的径向扩张速度与弹塑性交界面的径向扩张速度之比应满足的关系式。最后结合沉桩扩孔速度的已知条件推导出沉桩后桩周土体塑性区、破坏区的范围。整个土体范围内应力、位移表达式形式仍与不考虑沉桩扩孔速度因素时一样。对比分析表明:相同桩径条件下,随着沉桩扩孔速度的增加,沉桩影响范围也越来越大;随着桩径的增加,沉桩影响范围受沉桩扩孔速度的影响程度则降低。此外,相应于一定的桩径存在一个临界速度,当沉桩扩孔速度大于临界速度时,需要考虑速度因素;小于临界速度时不考虑则是偏于安全的。本文的研究成果主要适合于软土。
The procedure of pile-driving is modeled by the cylindrical cavity expansion,the displacement and stresses of soil around the pile are deduced considering the velocity,i.e.,the movement status of the soil element in the elastic-plastic interface is chosen as a referent criterion,and the stresses,displacements of any point in the field are described as the functions of R and r,which denote the radius of plastic room and the distance of soil element to the center after the expansion respectively.The small-strain theory is used to obtain the equation where the relative velocity V-should be satisfied.Combining with the known condition of expansion velocity,the radius of plastic room and failure room of the soil around the pile after the pile driving can be deduced,and the forms of stresses and displacements are still the same as the case without the velocity effects.The analysis indicates that for the same pile diameter,along with the increase of pile-driving velocity,the affected area is also increased;the larger the pile diameter,the less effection of velocity on the the affected area.Furthermore,the velocity effect is necessary to consider,if the pile-driving velocity is higher than the critical one,especially for soft soil.
出处
《应用力学学报》
CAS
CSCD
北大核心
2009年第2期370-374,共5页
Chinese Journal of Applied Mechanics
关键词
柱形孔扩张理论
修正剑桥模型
相关联流动法则
沉桩扩孔速度
小变形
cylindrical cavity expansion theory,the modified Cambridge model,associated flow rule,velocity of pile driving,small-strain.
