剪胀性砂土中球孔扩张弹塑性解
发布时间：2019-05-09 03:36
【摘要】：目前砂土中球孔弹塑性扩张解无法合理考虑砂土的峰值强度和剪胀特性,因而其解答与实际情况存在一定偏差。为得出剪胀性砂土中球孔扩张问题的合理解答,采用砂土临界状态模型考虑球孔扩张过程中砂土剪胀特性和峰值强度对球孔扩张机制的影响,基于相关联流动法则推导了球孔扩张问题的弹塑性本构张量,进而在塑性区采用大变形理论并引入辅助变量,将球孔扩张问题归结为基于拉格朗日描述的一阶偏微分方程组的初值问题。在此基础上,结合孔周弹塑性边界条件求解得出了剪胀性砂土中球孔扩张问题的严格解答。通过与基于修正剑桥模型的球孔扩张解答相对比,研究了砂土峰值强度和剪胀特性对孔周土体应力状态和位移的影响规律。结果表明,基于砂土临界状态模型的弹塑性解答不仅可以合理反映球孔扩张过程过程中剪胀性砂土的峰值强度和剪胀特性,而且可退化为非剪胀性土体中的球孔扩张解答,因而可以更加广泛地应用于静力触探、静压沉桩等岩土工程问题中。
[Abstract]:At present, the elastic-plastic expansion solution of spherical holes in sand can not reasonably consider the peak strength and shear expansion characteristics of sand, so there is a certain deviation between the solution and the actual situation. In order to obtain a reasonable solution to the problem of spherical hole expansion in shear-dilatant sand, the critical state model of sand is used to consider the influence of the shear expansion characteristics and peak strength of sand on the mechanism of spherical pore expansion in the process of spheroidal expansion. Based on the law of correlated flow, the elasto-plastic constitutive model Zhang Liang for spherical hole expansion problem is derived, and the large deformation theory is adopted in the plastic region and the auxiliary variable is introduced. The problem of spherical hole expansion is reduced to the initial value problem of the first order partial differential equations based on Lagrangian description. On the basis of this, a strict solution to the problem of spherical hole expansion in shear-dilatant sand is obtained by combining the elastic-plastic boundary conditions around the hole. Compared with the spherical expansion solution based on modified Cambridge model, the influence of sand peak strength and shear expansion on stress state and displacement of soil around the hole is studied. The results show that the elastic-plastic solution based on the critical state model of sand can not only reasonably reflect the peak strength and dilatancy characteristics of dilatant sand in the process of spherical expansion, but also reduce to the solution of spherical expansion in non-dilatant soil. Therefore, it can be widely used in geotechnical engineering problems such as static penetration, static pressure pile sinking and so on.
【作者单位】： 同济大学岩土及地下工程教育部重点实验室;同济大学地下建筑与工程系;上海大学土木工程系;
【基金】：国家自然科学基金项目(41272288)
【分类号】：TU441
[Abstract]:At present, the elastic-plastic expansion solution of spherical holes in sand can not reasonably consider the peak strength and shear expansion characteristics of sand, so there is a certain deviation between the solution and the actual situation. In order to obtain a reasonable solution to the problem of spherical hole expansion in shear-dilatant sand, the critical state model of sand is used to consider the influence of the shear expansion characteristics and peak strength of sand on the mechanism of spherical pore expansion in the process of spheroidal expansion. Based on the law of correlated flow, the elasto-plastic constitutive model Zhang Liang for spherical hole expansion problem is derived, and the large deformation theory is adopted in the plastic region and the auxiliary variable is introduced. The problem of spherical hole expansion is reduced to the initial value problem of the first order partial differential equations based on Lagrangian description. On the basis of this, a strict solution to the problem of spherical hole expansion in shear-dilatant sand is obtained by combining the elastic-plastic boundary conditions around the hole. Compared with the spherical expansion solution based on modified Cambridge model, the influence of sand peak strength and shear expansion on stress state and displacement of soil around the hole is studied. The results show that the elastic-plastic solution based on the critical state model of sand can not only reasonably reflect the peak strength and dilatancy characteristics of dilatant sand in the process of spherical expansion, but also reduce to the solution of spherical expansion in non-dilatant soil. Therefore, it can be widely used in geotechnical engineering problems such as static penetration, static pressure pile sinking and so on.
【作者单位】： 同济大学岩土及地下工程教育部重点实验室;同济大学地下建筑与工程系;上海大学土木工程系;
【基金】：国家自然科学基金项目(41272288)
【分类号】：TU441
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