Study On Treatment Technology Of Compaction Piles And Residual Collapsing Volume Control Under Widen Roadbed Loads In Loess Zone

The collapsible loess layer is widely distributed in northwest and north China.In recent years,with the rapid development of China’s economy,the problem of saturation of high-grade highway traffic volume has become increasingly prominent.Widening and rebuilding is an effective way to solve this problem,which faced with enormous challenges brought by the collapse of loess foundations;In order to avoid excessive collapse caused by the increase of humidity in loess foundations,The cement modified lime soil pile treatment technology is a commonly used technical method in recent years.In this paper,based on the residual collapsibility volume control standards under the widening load in the collapsible loess region,cement lime soil piles are used to treat the loess foundation under the newly widened area,and the deformation characteristics of the subgrade before and after treatment are analyzed;This paper is intended to verify the rationality of the residual collapsing volume control standards,study the otherness,analyze the causes of the otherness,and optimize the residual collapsing volume control standards according to relevant research conclusions,and draw the following main conclusions :(1)Through the compaction test,the relationship between the optimum moisture content of cement-modified lime soil and the amount of cement incorporation was obtained,and the change law of the strength of the modified lime soil with different cement content with the age growth was obtained by the direct shear test.(2)With the aid of geotechnical centrifuge model test,the roadbed deformation mode under the widen loads before and after humidification is clearly defined,and the existing residual collapsibility control standards is verified(3)Comparing with the model test data and numerical calculation results,the deficiency of the existing residual collapsing volume control standards was analyzed.Based on this,the residual collapsing volume control standards was optimized and supplemented by means of numerical calculation.