Experimental Study On Engineering Characteristic Of Loess In West Of Liaoning Area

The loess is the foundation and material of different engineering construction in the area of loess。Its distribution is extremely extensive in the world。And it has been being investigated as the central target in the fields of geotechnical engineering for many years. Scholars of domestic and international have developed a large amount of research work with respect to the characteristics of loess, and made great achievements. The loess centralizes mainly in the northwest of our country, Fuxin in west Liaoning and Chaoyang district are firstly listed in the loess edge district by the national standard"Architecture Criterion in Collapsible Loess Area"(GB50025-2004). With the development of economic construction in Liaoning, there are lots of engineering problems caused by special properties of loess in engineering construction especially in expressway construction, and the particularity of the loess of west Liaoning is paid to more and more attentions. There are quite diversities in project properties and loess collapsibility of different regions. At present most of studies on loess is about the Northwest of our country, and there is still few research in west of Liaoning area. So the extensive and profound investigations in engineering geologic characteristics of loess of west Liaoning, has certain significance not only in theory, but also in the engineering applications. In this paper, we take a sample in 16 segments from road section K312+890~K506+890 of highway between Chaoyang and Tieling, and collect a large number of materials, with which we complete lots of tests. According to the test data and relevant materials we have studied the physics mechanics properties of loess at thisarea. The thesis has been divided into five parts and I mainly specify the following three parts:The second part of the thesis firstly introduces the fields and experimental situations, and analyzes the experimental results of granule analysis experiments, the laboratory conventional experiments, laboratory triaxial experiments and scanning electron microscope (SEM) tests of loess from different positions and depths. By the granule analysis experiments, we have found that west of Liaoning area loess particle make up difference to be relatively loud compared with loess of other areas of our country. We simply discuss the origin of loess and primarily think it maybe the comprehensive contributing factors which mainly rely on the Aeolian function and the actions of flow erosion are accessorial. On the basis of a large amount of laboratory conventional experiments, we have obtained the physical and mechanical parameter of loess of the studying area. We also have compared the physical and mechanical parameter with loess of other areas in our country and made the relative analysis about them. By the laboratory triaxial experiments, we obtain its stress-strain curve and analyze the curve's characteristics. With the results of SEM tests, we have analyzed the micro-structural characteristics of loess from different depths in the studying area.At the third part of the thesis we firstly introduce the mechanism of collapsible deformation of loess and the influence factors of collapsibility of loess of studying area. With summarizing the achievements that forefathers have researched and combining the reality of the loess of studying area, we simply discuss the mechanism of collapsible deformation of loess and wethink that the basic reason that the loess collapses is the special composition and structure of the loess which makes for the loess collapse. Secondly, we have carried on the correlation analysis to the collapsible coefficient and physical parameters of the loess at the depth of 1-5m from the road section K312+890-K398+800 of Fuchao expressway, and we have found that the influence to the collapsible coefficient is quite prominent arose by dry density, water content and saturated degree, while the significance of influence by porosity ratio is ecumenical. Mathematical statistics is employed here to unary regression and multivariate regression analysis for the collapsible coefficient, dry density, water content and saturated degree, with which we provide the empirical formulas of this district. By checking each empirical formula we find all of them have a high significance while the correlation between collapsible coefficient and water content is the highest; finally we introduce the classification criterion for the loess collapsibility both at home and abroad, and have proposed the division standard to the loess of studying area in the thesis.At part four we introduce the disturbed state concept (DSC). Here we set up the uniaxial compressive stress-strain model and then verify the model. The results reveals: the value calculated with formula is a little greater than the experimental strain value if they have the same stress; and when the stress is smaller, the difference of the two values is relatively small and the values is comparatively close, while their laws of changes are similar; generally speaking, the results of the model and results from experiments are comparatively identical.We have carried on systematic research to the engineering characteristicsof loess of west Liaoning area through a large number of experiments in the thesis. We summarize physical mechanics properties of loess this area, and we take research in grain composition, micro-structure, genesis and collapsibility of the loess. We also employ the methods of mathematical statistics to build the relativity between the collapsible coefficient and the physical parameters of loess this area, and appraise to the collapsibility of the loess. Finally we introduce the disturbed state concept (DSC), and set up the uniaxial compressive constitutive model.