Research On Sher Strength And Influence Mechanism Of Calcareous Soil

Calcareous soil is a kind of special geomaterials,formed by marine biology(coral,seaweed,shells,etc.),and it is rich in calcium carbonate or other insoluble carbonate substances.Its special properties are mainly manifested in the multihole soil particles(containing inner porosity),irregular shape,easily broken,easily to be cemented and so on,so that significant differences in the mechanical properties of engineering show up,comparing with general continental,marine sediments.The special causes of calcareous soils leads to its distribution are consistent with the coral reefs,and the calcareous soils which in coral reef areas are often used as filling materials in engineering construction.Since the national implementation of the marine power strategy,the coral island distract construction more and more,the project scale is getting bigger and bigger,the engineering problems are becoming more and more complicated,the physical and mechanical properties of calcareous soil is unclear may cause engineering accidents and the waste of investment.Therefore,it is urgent to study the engineering characteristics of calcareous soil in the South China sea reefs.1.According to the results of geological survey of hydraulic filled calcareous soil foundation,a large number of triaxial shear tests are designed for the characteristics of calcareous soils foundation.The shear characteristics of calcareous soil under triaxial test conditions are described.For the particle size,gradation,compactness,confining pressure,drainage condition,water content and other factors and the relationship between shear strength were analyzed,2.The simple analysis for particle breakage model and the crushing mechanism and the influence factor were carried out.The relative crushing rate model proposed by Hardin was used to quantify the results of particle crushing,and the particle breakage under different experimental conditions was compared.3.Using the Mohr-Coulomb criterion,the Rowe dilatancy equation to divide effective internal friction angle of the calcareous soil into sliding friction component,dilatancy component,particle crushing component,the mechanism of strength under different experimental conditions of calcareous soil is analyzed.4.Contrasted the effective internal friction by Mohr envelope fitting method with calculated value by Mohr-Coulomb yielding criterion,calculation value is generally larger than the actual values,the reason is the strength of the measured value is divided into "C"and "?",but the calculated value only include "?".The "C" of calcareous soil shear test is analyzed,and it is pointed out that there is an apparent cohesion in the consolidated drained test of calcareous soil,but it is not equal to "C" This force is generated by the occlusal effect,affected by the dilatancy.