不同升温方式下饱和粉土孔压及不排水剪切特性分析OACHSSCD

Geothermal energy induces temperature changes that can alter soil properties,thus affecting the safety of underground energy engineering.To further investigate the influence of temperature change on the consolidation and strength characteristics of soil,undrained shear tests were conducted on saturated silt using a temperature-controlled triaxial test system.The effects of temperature on pore pressure and strength characteristics were analyzed under two heating methods;undrained heating and drained heating,for saturated silt from Nanjing.Ladd's normalized strength theory of soil was employed to analyze the undrained shear strength of the undrained heating specimens.The results are summarized as follows.During undrained heating,the pore pressure of saturated silt increases while the effective stress decreases.The transformation of effective stress leads the soil into an unstable stress state.The heating condition affects the development of pore pressure in the early stage of undrained shear:in undrained heating specimens,the accumulated thermal pore pressure slows the change in pore pressure during shearing,while in drained heating specimens,the initial pore pressure is zero,and the pore pressure rises quickly at the beginning of shearing.The heating path affects the early undrained shear behavior of saturated silt differently:undrained heating weakens the characteristic features of the specimen's stress-strain curve,while drained heating strengthens them.The greater the temperature rise,the more significant the weakening or strengthening effect.The thermal over-consolidation ratio(TOCR)effectively characterizes the influence of temperature on the undrained shear strength of the soil and can be described using Ladd's formula for the normalized shear strength of overconsolidated soils.