增湿-冻融劣化原状黄土结构强度模型

为了后续研究工作能将原状黄土结构强度在实际工程中推广与应用,本文续增湿-冻融劣化原状黄土结构强度试验研究,力图建立其结构强度的劣化模型。研究工作如下：(1)依据原状黄土压缩曲线定义黄土结构强度、残余结构强度和结构强度损伤变量等概念,并分析损伤变量可表征黄土结构强度劣化过程;(2)基于Weibull分布和损伤力学应变等价性假设,建立了以体积膨胀率作为考察变量的黄土微观取样制样扰动、吸水增湿和增湿-冻融循环耦合统计损伤模型,统计损伤演化函数及黄土结构强度损伤基本方程。(3)在试验数据的基础上,确定了模型参数,并取西安北郊某基坑黄土对模型进行验证,与试验吻合性较好,研究成果能方便指导现场工程设计和施工。

Structural Strength Deterioration Model of Undisturbed Loess by Moistening and Freezing-thawing

In order to follow up and apply this research work in practical engineering, this paper continues to study the structural strength deterioration test of undisturbed loess by moistening and freezing-thawing, and tries to establish the deterioration model of structural strength. The research results are as follows: Firstly, according to the compression curve of undisturbed loess, the concepts of structural strength, residual structural strength and structural strength damage variable are defined. And the damage variable can characterizing the process of strength degradation of loess structure is explained in detail. Secondly, based on Weibull distribution and damage mechanics strain equivalence hypothesis, the loess statistical damages models of sampling and sampling disturbance, moistening, and moistening and freezing-thawing cycles coupling action, statistical damage evolution function and basic equation of loess structural strength damage are established with volumetric expansion rate as the investigate variable. Finally, on the basis of the test data, the model parameters are determined, and the models are verified by taking a foundation pit loess in northern suburbs of Xi"an, and are in good agreement with the test. Research results can guide for on-site engineering design and construction.