Study On The Rheological Properties Of Paleo-clay In Hefei Area

In this paper,paleo-clay in hefei area is taken as the research object.Various factors affecting the rheological characteristics of paleo-clay in hefei area are studied by combining laboratory test and theoretical analysis.The rheological characteristics of paleo-clay are deeply studied by comparing the rheological properties of rock and soil mass with significant rheological properties.The experimental soil is taken from typical undisturbed old clay with fissure,expansibility,overconsolidation and shear dilatancy in Hefei area.The basic properties of old clay in Hefei area are expounded by testing the basic physical properties of old clay and collecting the relevant literature of old clay in Hefei area.The slow shear test was carried out with the quaternary iso-strain direct shear apparatus,and the shear rate was controlled at a speed of 0.01 mm/min to obtain the shear strength of the paleo-clay in hefei area under the condition of slow speed,and the long-term strength of the paleo-clay was compared and analyzed.Stress controlled by modified by quad direct shear creep apparatus to creep test of the paleo-clay,get paleo-clay in hefei area rheological test data,the analysis of test data for study of hefei shear creep characteristics of typical paleo-clay,and different under the different moisture content under the action of vertical pressure and shear rheological test results under different plasticity index were analyzed,and made the following main conclusions:(1)under the condition that the vertical pressure remains unchanged,with the increase of water content,the shear stress,shear displacement,load duration and long-term strength of the paleo-clay decrease with the increase of shear creep failure.(2)under the condition that the moisture content remains unchanged,the time,shear stress and long-term strength of the paleo-clay increase with the increase of the vertical pressure.The shear displacement decreases with shear creep failure.(3)under the condition that the moisture content and density of the soil sample are very similar and the vertical pressure remains consistent,the soil sample with a higher plasticity index will have greater shear displacement and shear stress,stronger viscosity and longer creep failure time when shear creep failure occurs.The rheological properties of soft clay and soft rock are compared with that of paleo-clay.The rheological properties and laws of these three kinds of rock and soil masses are discussed by controlling the test instruments,test methods and the propertiesof the samples.The results show that the rheological property of the paleo-clay in hefei is between that of suzhou soft soil and changchun soft rock,and the rheological property of suzhou soft soil is the most significant,followed by hefei paleo-clay,and finally changchun soft rock.Through the above methods,the essential law of rheological characteristics of paleo-clay in hefei area is mastered,which provides reliable design and constructive basis for the treatment method and engineering construction of paleo-clay in hefei area.