岩土材料弹性力学模型与计算方法

ELASTIC MECHANICAL MODEL AND COMPUTATION METHOD OF GEOMATERIALS

岩土材料内摩擦性质是岩土的基本力学性质之一,无论岩土处于何种受力状态,都应考虑岩土体的内摩擦力。然而,至今只有岩土极限分析与塑性力学中考虑岩土体的内摩擦力,而在弹性理论与能量理论等诸方面均未体现。岩土体无论是处于塑性状态还是弹性状态,都存在着内摩擦力,为此建立岩土材料弹性力学的摩擦体力学单元。基于土体试验提出黏聚力先发挥,摩擦力随变形逐渐发挥,并假设摩擦因数与应变成正比,由此确定摩擦力的计算,最后仿效线弹性力学计算方法,但此时摩擦体的剪切模量G已非常数,从而形成摩擦体的非线性弹性力学计算方法。算例表明,按该方法计算出的弹性地基上的位移和剪应力小于传统方法计算出的位移和应力值,这比较符合实际情况,表明采用摩擦体力学单元对岩土材料是合适的。

The internal friction character is one of the basic properties of geomaterial, and the internal friction exists in mechanical elements all the time. However, until now the internal friction is only considered in limit analysis and plastic mechanics, but not included in elastic mechanics and energy theory. It is considered that the internal friction exists whether in plastic state or elastic state, and the mechanical elements of friction material are constituted based on this cognition. According to the research of soil tests, it is presented that the cohesion takes effect firstly, and then the internal friction increases gradually with the increment of deformation. By assuming that the friction factor is proportional to the strain, the internal friction is computed. At last, by imitating the linear elastic mechanics, the nonlinear elastic mechanical model of friction material is established, where the shear modular G is not a constant. The new model and the traditional elastic model are used simultaneously to analyze an elastic foundation. The results indicate that the displacement and the shear stress computed by the new model are smaller than those of the traditional model, which is in agreement with the fact. So it is suitable for geomaterial to adopt the mechanical elements of friction material.