摘要
静止土压力系数K_(0)描述土体的原位应力状态,是许多工程计算的重要参数。本文通过等应变速率K_(0)固结试验,研究原状和重塑马兰黄土的K_(0)变化规律,并探讨这种变化与内部结构的关系。结果表明:(1)原状和重塑马兰黄土的K_(0)均不是恒定值,根据土体结构的变化,其固结过程可分为初始阶段和稳定阶段。初始阶段K_(0)(以K_(0i)表示)随含水率的增加呈线性增长,稳定阶段K_(0)(以K_(0s)表示)随含水率的增加呈双曲线增长,且K_(0s)始终大于K_(0i)。(2)原状马兰黄土的K_(0i)小于重塑马兰黄土,原因在于原状马兰黄土具有很强的簇聚结构,这种竖向结构弱化了水平应力的增长;而重塑马兰黄土趋于均质,呈各向同性,进而导致较高的K_(0i)。(3)稳定阶段,原状马兰黄土的初始结构被破坏,与重塑马兰黄土近似,使得两者的K_(0s)相近。(4)相较于其他类土,原状马兰黄土的K_(0s)始终呈现较小值(饱和原状马兰黄土的K_(0s)基本稳定在0.45左右,而其他类土可高达0.8)。通过对不同K_(0)下的边坡进行数值模拟,发现低K_(0)土体更易于在坡顶区域形成近直立的深长拉张裂隙,这也是典型黄土地貌(如黄土墙、黄土柱)形成的重要原因之一。
The static lateral pressure coefficient,K_(0),describes the in-situ stress state of soils and is an important parameter in engineering calculations.In this paper,K_(0)consolidation test at constant strain rate is conducted on the Malan loess at different water contents to investigate the variation of K_(0).Both intact and remoulded specimens are employed and tested.It is found that:(1)K_(0)of Malan loess is not a constant value.According to the structural evolution during the test,the consolidation process can be divided into pre-collapse and post-collapse stages.K_(0)of the pre-collapse stage(K_(0i))increases linearly with increase in water content,while that of the post-collapse stage(K_(0s))follows a hyperbolic growth pattern with increase in water content.In addition,K_(0s)is always greater than K_(0i).(2)The K_(0i)from the intact specimens is less than that of the remoulded ones.The intact Malan loess has a strong vertical structure,which weakens the development of horizontal stress.The remoulded Malan loess is homogeneous and isotropic,resulting in a higher K_(0i).(3)In the post-collapse stage,the original structure of the intact specimens is destroyed,resulting in a structure similar to that of the remoulded specimens.This makes comparable K_(0s)values for both intact and remoulded Malan loess.(4)Compared with other soils,K_(0s)of Malan loess always show a lower value(K_(0s)of saturated intact Malan loess is about 0.45,while that of other soils can be as high as 0.8).Numerical simulation of slopes under different K_(0)values shows that soil with low K_(0)is more susceptible to the formation of deep vertical tensile cracks.This to some extent explains the formation of typical macroscopic landform,such as loess wall and loess column.
作者
张宗福
李彦荣
王蓉
郭亮亮
ZHANG Zongfu;LI Yanrong;WANG Rong;GUO Liangliang(Taiyuan University of Technology,Taiyuan 030000,China)
出处
《工程地质学报》
CSCD
北大核心
2022年第4期1036-1043,共8页
Journal of Engineering Geology
基金
国家自然科学基金面上项目(资助号:41877276)。
关键词
静止土压力系数
K_(0)固结
马兰黄土
簇聚结构
拉张裂隙
Static lateral pressure coefficient
K_(0)consolidation
Malan loess
Vertiloess structure
Tension crack
