高层建筑深基础沉降计算的黏弹性分析

VISCOELASTIC ANALYSIS FOR THE SETTLEMENT CALCULATION OF DEEP FOUNDATION OF HIGH-RISE BUILDINGS

研究假定土体为线性黏弹性介质,其在内部力作用下的应力球张量和应变球张量间符合弹性关系,而应力偏张量和应变偏张量间符合三参数固体黏弹性应力应变关系。基于半空间体内部受竖向集中力的Mindlin弹性解,根据弹性-弹黏性相应原理,推导了竖向集中力作用在半无限体内部时的竖向位移黏弹性解。通过对位移解进行Laplace逆变换,给出了竖向位移的时域解。作为解答的应用,推导了三参量固体黏弹性半无限体内部矩形面积上作用有三角形分布、均匀分布荷载时的黏弹性沉降计算式。将深基础视为一等代实体墩基础,建立了置于非均匀地基中的桩基础黏弹性沉降计算方法。为了便于计算与工程应用,根据黏弹性理论解编制了计算程序。结果验证与实例分析表明,文中理论解是正确的,研究结果为工程实际应用提供了理论依据。

By means of half-space Mindlin＇ s elastic solutions and correspondence principle between elasticity and viscoelasticity, the viscoelastic solution of displacement, subjected to suddenly applied vertical force and given elastic volume strain and standard linear solid model distortion constitutive relations, is derived from the Laplace transform. The solutions in time domain is established by the inverse Laplace transform. Based on the viscoelastic solution of vertical displacement, the settlement formulas for the center and corner point of a flexible rectangular foundation made by homogeneous distributing load on rectangular area beneath the surface of ground are systematically inferred. A computation program is compiled based on the developed solutions. Finally, an example was given by making use of the presented method. The calculation results show that the new theory is feasible and applicable and can successfully predict the settlement of deeply buried foundation. And the results show that it is necessary to take account of viscoelasticity effect of semi-infinite half-space in the calculation of stress and displacement.