| Frost heave and thawing settlement are cold and engineering is facing two major diseases,often result in the crack of the houses,tilted and deformation,lead to railway,highway culvert side wing wall crack,extraversion;The mud pumping in highway,railway subgrade deformation,cracking,etc.In recent years,this phenomenon have take place great trouble to the construction on the region.So it is very impotant to research the mechanics mechanism of Pisha-sandstone remolded soil under the effect of freezing and thawing cycle.The Pisha-stone area of Inner Mongolia has a temperate continental climate with four clearly distinct seasons and there have a large number of seasonal frozen soil.As for the winter and spring,when the night comes,the temperature goes down rapidly,which is called "freezing";And the temperature raises rapidly with the solar radiation in the day,which is called "thawing".Repeated alternation and conversion of freezing and thawing processes changes the structural connection and arrangement mode of the Pisha-sandstone soil,leading to changes in its physical and mechanical properties.This article searches on amaranth Pisha-sandstone remolded soil of jungar banner in southern ordos city of Inner Mongolia,conducting different freeze-thaw cycles,different confining pressure and water cut to do triaxial shear test under normal temperature.The results indicate that:In the same freeze-thaw cycle index,the effect of freezing and thawing cycle against the shear strength is mainly manifested in the cohesion of influence;In the same freeze-thaw cycle index,with the increase of confining pressure,the peak of shear strength is linear growth,for which the cohesion of Pisha-sandstone decreases with the increasing moisture content,and internal friction Angle fluctuates with the increasing of moisture content.Through the analysis of the change of the stress-strain curve,change the parameters of the reaction intensity is introduced,the degradation coefficient,are analyzed under different freeze-thaw cycles,the changes of the arsenic sandstone degradation coefficient,it is concluded that result in the change of remolded soil arsenic sandstone strength parameters mainly for the cohesion of C value changes.Basing on it,then analyze the hardening properties and softening properties of stress—strain curve of Pisha-sandstone remolded soil after comparing the relationship between Pisha-sandstone peak strength and residual strength under different numbers of freeze-thaw cycle.According to Duncan-Chang model on Pisha-Sandstone remolded soil,this paper calculates the parameters a and b,and the rate of soil failure.And the stress-strain relationship of Pisha-sandstone is analyzed and predicted by this model.If the result is close to predicted with measured results and show that the model can well reflect the constitutive relation with remolded Pisha-sandstone soil under different moisture content and confining pressure. |
