Experimental Study On Improving Expansive Soil With Biopolymer

Expansive soil is a kind of cohesive soil.Its volume expands rapidly when immersed in water and shrinks rapidly when taken out of water.The use of expansive soil in buildings causes serious harm.At present,the commonly used method to improve expansive soil is to add cement,fly ash,soil curing agent,lime,cinder and other substances into expansive soil.These improvement measures will cause environmental pollution,increase construction difficulty,increase cost and so on.In this paper,the biological polymer improved expansive soil such as xanthan gum and quicklime improved expansive soil,and the xanthan gum and quicklime mixed into the improved expansive soil are selected for comparative tests.The boundary water content test,expansion rate test,expansion force test,direct shear test,scanning electron microscope test and the prediction model based on MATLAB are carried out for the expansive soil.Through the above tests,the addition of quicklime The influence of yellow collagen and quicklime and yellow collagen in a certain proportion on the physical properties,mechanical properties,swelling properties and microstructure of expansive soil,and the prediction model is established to summarize the laws,providing a new method and idea for the improvement of expansive soil in the future.The research results are as follows:1.Through the test of improving expansive soil with different additives,the change laws of various indexes such as plastic limit,liquid limit,plastic index,expansion force,loaded expansion rate and shear strength of the improved expansive soil are analyzed.It is concluded that the effect of xanthan gum improving expansive soil is better than that of quicklime improving expansive soil and xanthan gum and quicklime adding together to improve expansive soil.2.By comparing the improvement effects of adding quicklime,xanthan gum and different proportions of quicklime and yellow collagen to expansive soil,the best proportion of biopolymer to improve expansive soil is obtained,which is 0.5%.3.The microstructure of improved expansive soil was studied by scanning electron microscope test,and the mechanism of xanthan gum and quicklime improving expansive soil was revealed.4.Based on MATLAB software,the regression prediction model of expansion rate and expansion force of expansive soil improved by different additives is established through SVR algorithm,the comparison diagram between the predicted value and the real value is obtained,and the predicted value is fitted to obtain the formula.5.According to the research results of this paper and the research theory obtained by previous experts,new improvement suggestions are given for the problems existing in the treatment of expansive soil subgrade.