Study On Shear Rheological Behavior Of Foamed Mixture Soil Using River Sludge

With the rapid development of China’s economy and the accelerating the process of urbanization,two practical problems that the shortage of engineering soil and the deterioration of the ecological environment should be solved quickly.For these reasons,a new type of geotechnical material was produced by using a large amount of river sludge produced annually in China,which can not only alleviate the shortage of engineering soil,but also make the waste resources be effectively used and improve the ecological environment.At present,it is a hot research topic in the field of geotechnical engineering to improve the use of river sludge.River sludge is a kind of soft clay,and rheological behavior is one of the most important engineering properties of soft clay.According to the investigation,it is found that a large number of engineering accidents occurred in practical engineering are related to the rheological behavior of soft soil.These engineering accidents,such as the tilt of gravity dam,the long-term settlement of the foundation and the instability of the slope along with the increase of time,all indicate that the influence caused by the rheology of the soil can not be ignored.At present,the study on rheological properties of soil is mainly based on natural original soil,and the rheological properties of artificial soil are less.Therefore,this paper studies the shear rheological properties of the foamed mixture soil using river sludge,which is developed for the purpose of engineering application,the main research work is as follows:First of all,the experimental mixing ratio of the foamed mixture soil using river sludge was designed,and the direct shear test and shear rheological test were carried out.The experimental results show that the curve of shear rheology mainly presents three models.When the shear stress level is low,the rheological curve appears as attenuation stable;When the shear stress levels continue to increase,the form of the rheological curve is not stable but constant speed type;When the shear stress increases to a certain extent,the rheological curve type was accelerated.From the rheological properties of the mixed soil,the increase of curing age and the incorporation of cement can improve the shear strength of the mixed soil and weaken the rheological behavior of the mixed soil;with the increase of the air bubble and the water content,the shear strength and the rheological properties of the mixed soil were decreased.Secondly,according to the test,a reasonable shear rheological model is selected to analyze the rheological curve.The results show that the model can reasonably and reliably describe the rheological process include attenuation,velocity and acceleration of the mixed soil under various shear stress levels.Based on the experimental results and the parameters of the shear rheological model,through reasonable optimization design,it can be obtained the mixed soil with strong resistance to shear rheology.Finally,based on the shear rheological characteristics of the mixed soil,ABAQUS software was used to analyze the slope stability of stepped mixed soil.The results show that the toe is the weakest part of the shear strength of slope.Due to rheological deformation,plastic sliding zone first appear at the bottom of slope.As time goes on,the plastic sliding zone extends to the slope,and the stability coefficient of the slope increases gradually.The safety factor of slope stability at all levels is greater than 1,which indicates that as a fill of a slope,the foamed mixture soil using river sludge is safe and feasible.