摘要
基于Biot动力固结理论,研究桩周径向非均匀饱和土体的扭转振动问题。首先,将径向非均匀土体分为内部环形扰动区域和外部半无限大未扰动区域,并进一步将内部扰动区域土体分为多个薄层同心圆环区域。然后,在平面应变条件下推导得到饱和土体受谐和扭转荷载作用的动力控制方程,并求得土体扭转振动位移形式解。进一步结合径向土层之间的边界条件和衔接条件,采用剪切刚度传递的方法,得到土体的扭转阻抗。最后,在低频范围内分析成桩施工导致的桩周土体参数变化对土体扭转阻抗的影响,并将该解与现有解进行对比。结果表明,(1)土体硬化程度越大,土体扭转阻抗的刚度和阻尼部分越大;(2)土体软化程度越大,土体扭转阻抗的刚度和阻尼部分越小;(3)在2倍桩径范围内,内部区域宽度越大,硬化土体扭转阻抗的刚度部分越大,软化土体扭转阻抗的刚度部分越小;(4)当激振频率较小时,内部区域土体材料阻尼对土体扭转阻抗的刚度部分基本没有影响。
Based on Biot＇s dynamic consolidation theory,the torsional vibration of radially inhomogeneous saturated soil surrounding a pile is theoretically investigated.At first,the radially inhomogeneous soil is divided into inner annular disturbed and outer semi-infinite undisturbed regions,and the inner disturbed region is divided into many thin concentric annular zones.Then,the dynamic governing equation of saturated soil undergoing axisymmetric torsional deformations is derived in cylindrical coordinates.By utilizing the properties of modified Bessel function,the vibration displacement solution with undetermined constants of the soil layer is obtained and the solution holds for each thin concentric annular zone.Under the boundary and continuity conditions of the radially inhomogeneous soil layers,the torsional impedance of saturated soil is derived by means of transfer of shearing rigidity.Finally,the influence of changes of soil parameters caused by pile construction effect on torsional impedance of the soil is analyzed within the low frequency range;and several available solutions are compared with the present solution.The results show that：（1） The greater the hardening extent of the soil is,the higher the real stiffness and damping of the soil are;（2） The greater the softening extent of the soil is,the lower the real stiffness and damping of the soil are;（3） Within the two times of the radius of the pile,the larger the width of the inner region is,the higher the real stiffness of the hardening soil is and the lower the real stiffness of the softening soil is;（4） When the excitation frequency is relatively low,the material damping of inner region has negligible influence on the real stiffness of the soil.
出处
《岩石力学与工程学报》
EI
CAS
CSCD
北大核心
2010年第8期1721-1728,共8页
Chinese Journal of Rock Mechanics and Engineering
基金
国家自然科学基金资助项目(50879077)
浙江省科技厅优先主题重点项目(2007C13065)
浙江省教育厅2009年度科研计划项目(Y200909351)
关键词
土力学
径向非均匀饱和土
平面应变
剪切刚度传递
扭转阻抗
soil mechanics
radially inhomogeneous saturated soil
plane strain
transfer of shearing rigidity
torsional impedance
