Research On Strength Characteristics And Constitutive Relationship Of Strongly Expansive Soft-rock In Yanji Basin

The constitutive relationship of expansive rock at home and abroad has been studied for more than 30 years, but this research of constitutive relationship of the expansive rock has quite a distance from guiding engineering practice. Therefore, this study paid attentions on the expansive characteristics ,strength characteristics and constitutive relationship of undisturbed and remolded expansive rocks .Also,this study,which had combined the characteristics with the geological background of rock ,has a great significance for the projects in the area full of expansive rocks in the future,due to the research was the combination of the geological setting, deformation mechanisms and constitutive relationship.The expansion characteristics and strength properties of undisturbed and remolded soil under different conditions are respectively studied in this paper,according to a series of experiments in room,in which light dilatometer, double oedometer, direct shear apparatus and the conventional unconfined compression apparatus, etc.The main achievements in this paper can be obtained as follows.1.On the domestic and international study of the constitutive relationship of expansive rock are reviewed, and a certain and initial understanding of the swelling rock,s constitutive relation had been had.Then, the mineral composition, microstructure and physical and mechanical properties of the Yanji Basin expansive rock was determined through X-ray, scanning electron microscopy, determination of physical and mechanical laboratory , the type of expansive rock was confirmed, and the region's geological background and expansive nature of the rocks was realized primarily.2.Summary expansion mechanism and influence factors of the expansive rock, based on the laboratory tests of the expansive rocks in Yanji Basin, including no-load expansion and expansion capacity test of the original and remodeling soils under different moisture content . Analyse the test results and explore the constitutive relationship between the swelling strain and moisture content .3.Through the routine direct shear stress testing and unconfined compression tests of the different initial moisture content of the original expansive rocks ,as well as different initial moisture content of the remodeling expansive rocks and the ones which had expansive at different times, to sum up the stress-strain behavior of the expansive rocks under different water content and vertical pressure. Then analysis and search for the relations between the initial water content, vertical pressure , the moisture content of the rocks expansive for different times and shear strength and parameters of shear strength including cohesion and internal friction angle , and expansion of After swelling and, and establish the quantitative relationship of anti- shear strength, cohesion, internal friction angle and initial moisture content and moisture content after expansion , and fit regression equation of the relationship between the water content and compressive strength .4.Through summarying the relationship between the expansion deformation and shear strength, uniaxial compressive strength and moisture content, and combining with the engineering practice, look for the optimum water content in the construction process of the area full of swelling rocks.