Experimental Study Of Soil Mechanics Under Different Loading Path

Rock layer of the earth withstands long-term weathering and fragmentation in the atmosphere to form particles in different shapes and different sizes.Under the effect of a variety of natural forces,these particles would undergo a long term accumulation and the natural soil would go through a structural change.For submarine process,the structural change of soft soils occur more obviously.Soft oil with different structures may have a sudden change in the actual application,which will generate a significant impact on the project construction.Most of the formation disturbance due to construction will lead to changes in stress state and strain.Moreover,stress and stain change are related to the loading path.In this paper,the effect of different loading paths on the mechanical properties of soft soils are discussed.Relevant conventional triaxial tests are carried out while simulation of particle flow under different loading paths are conducted.It is of great significance to study the soil mechanics from the perspectives of soil structure,loading path and stress level for soft soil based project.The main contents and conclusions include:1.Indoor consolidated drained and consolidated undrained experiments are conducted and compared.Experimental results indicate that the cohesion force of the soil is 57.59 KPa and the internal friction angle is 15.16°.Comparing these two experiments,we find that under the consolidated undrained experiment,the overall bearing capacity of the rock itself is much higher than that of the consolidated drained experiment due to the existence of the pore pressure.2.Numerical simulations of Soil consolidated drained experiments are conducted based on discrete element method.The discrete element method is one of the most popular calculation methods to simulate the soil mechanics.Comparing the calculated results with the experimental results,the loading process of the soil is divided into compaction stage,elastic stage,elastic-plastic stage and post peak stage.With the increase of the confining pressure,the proportion of the four stages in the whole process will change.When the confining pressure is low,the compaction stage and the elastic stage is relatively long,the yield stage is relatively short,and the soil is brittle.When the confining pressure rises,the plasticity of the soil becomes more and more obvious.3.Based on discrete element method,numerical simulations of soil consolidated experiments at fixed pore pressure are carried out.Similar to the results of the consolidated drained experiment,the stress curve of the soil consolidated experiments at fixed pore pressure can also be divided into four parts.Simulation results show that the shear fracture zone is more than one in fixed pore pressure experiments while the drainage experiment only has a single shear zone.The change of pore pressure is actually causes the change in the effective stress of the rock.The increase of the pore pressure is to reduce the initiation of the tensile crack to a certain extent,which makes the crack propagation more prone to shear damage.