Study On The Moistening Process Of Undisturbed Soil Based On Triaxial Stress

Collapsible loess is a kind of loess,it is widely distributed in China and almost covers the whole northwest region.With the implementation process of Western Region Development in China,the number of construction projects in Northwest China is increasing.Thus,collapsible loess is inevitably used as building material,foundation and workplace.All these require us to have a comprehensive and scientific grasp of its engineering properties so as to achieve the purpose of safety and reliability in the constructions.The collapsibility test in laboratory is usually based on consolidation instrument,which is carried out under complete lateral limit condition.Actually,when collapse occurs under pressure,there will be vertical and horizontal deformation simultaneously.Therefore,we plan to carry on this experiment under triaxial condition.The triaxial tests about collapsible loess in tradition always adopt strain form,which can not make the soil sample carry the load completely when the collapsible deformation is greater than the axial displacement.And that is why the SR-6 triaxial creep meter is specially modified to measure the data under stress loading.In this paper,the triaxial test uses undisturbed loess in Yangling area as sample and adopts bottom-up graded immersion method to make the samples soaked.The main method of this experimental study is to control a single variable and measure the collapsibility coefficient under different stress,different confined pressure,different initial water content and different humidification degree.Finally,many charts and figures are drawn to analyze the law about collapsible loess.And the main conclusions are as follows:(1)The compressibility of the sample will be higher,with a high initial water content,a high stress or a low confined pressure.(2)The collapsibility coefficient is positively correlated with stress.The larger the stress is,the larger collapsibility deformation and collapsibility coefficient will be.(3)The collapsibility coefficient is negatively correlated with confined pressure.The larger the confined pressure is,the smaller collapsibility deformation and collapsibility coefficient will be.(4)The collapsibility coefficient is negatively correlated with initial water content.The larger the initial water content is,the smaller collapsibility deformation and collapsibility coefficient will be.(5)The collapsibility coefficient is positively correlated with humidification degree.With the increase of humidification degree,the collapsibility coefficient will increase sharply at first,then grow up gradually and finally keep steady.Collapse mainly occurs when the humidification degree is low.And when the sample is continuously wetted to a higher saturation,the collapsible deformation will not happen anymore.(6)The influence of stress,confined pressure,initial water content and humidification degree on the collapsibility coefficient is not single.Their own effect on the collapsibility coefficient is also affected by other factors.Generally speaking,the effect on collapsibility coefficient will be more obvious with a higher stress,a smaller confined pressure,a lower initial water content or a lower humidification degree.Meanwhile,the effect of humidification degree on the relationship curves is not great.