Experimental Study On The Influence Of Temperature On Compression Characteristics Of Cohesive Soil

With the deterioration of the earth’s environment and the exhaustion of available resources,energy conservation and emission reduction has become the consensus of mankind.As an effective solution for energy conservation and emission reduction,energy geotechnical engineering has received more and more attention.At present,in the practical application of energy geotechnical engineering,geotechnical engineering structure will undergo temperature changes,which will cause changes in the properties of clay,and the theoretical system of the influence of temperature on clay is not perfect.In this paper,the compressive properties of clay under thermal-mechanical coupling are studied by using a temperature-controlled triaxial apparatus.Considering different temperature-stress loading paths,the maximum temperature change is 40℃.The effects of effective stress,stress history and temperature history on temperature-volume strain of clay are analyzed.The temperature responses of clay to compression index,resilience index and yield stress are studied.The main conclusions are as follows:(1)There is a critical temperature in the process of temperature rising.When the temperature is lower than the critical temperature,the volume of clay increases with the increase of temperature;when the temperature exceeds the critical temperature,the volume of clay decreases with the increase of temperature,and the critical temperature increases with the increase of OCR.During the cooling process,the volume strain of clay decreases linearly with temperature,and the slope of the volume strain of OCR varies with temperature is similar.(2)At the same temperature increment,the temperature volume strain of clay has nothing to do with the effective stress of the current soil,mainly depends on the OCR value of clay.The larger the OCR value of clay,the smaller the temperature volume strain.(3)Temperature cycling will lead to the accumulation of plastic volumetric strain of clay.The plastic volumetric strain of clay increases with the increase of temperature cycling times and tends to be stable gradually.The larger the OCR value of clay,the faster the plastic volumetric strain tends to be stable,that is,there is a temperature history effect on the temperature volumetric strain of clay.(4)If the clay specimens which have undergone temperature cycling are reloaded to the normal consolidation state,the plastic volume strain value and its development law in the subsequent temperature cycling are similar to those in the initial cycling,that is,the temperature history effect will be covered by stress loading.(5)The compression and resilience index of clay are not affected by temperature.(6)Under the condition of equal plastic strain,the yield stress of clay decreases with the increase of soil temperature,and the plastic volume strain produced by the temperature and mechanical load of clay has similar hardening effect on the yield stress.The expression considering the effect of temperature on the yield stress of soil is suggested.