Study On Filling Technology Of Modified Subgrade With High Moisture Granite Residual Soil

The strongly weathered granite residual soil as a kind of natural soil with wide distribution and poor engineering performance,based on its great economic potential of modified soil as roadbed filler,It is necessary to study the modification method and filling technology under the environment of promoting environmental protection and sustainable development.Based on the practical project of ZhuZhou airport road,this paper systematically studied the modification mechanism and performance change of lime and cement improved granite residual soil by means of theoretical research,laboratory experiment and numerical simulation.A set of modified proportion and filling scheme for the granite residual soil of zhuzhou airport road was initially formed.The main research results are as follows:(1)The chemical composition and physical-mechanical properties of the granite residual soil in this area were studied through laboratory tests,the results show that the soil is loose in structure and poor in water stability.The water content is much higher than the optimal water content,so the compaction degree of the filled roadbed cannot reach the standard.The soil load ratio is less than 4,only meet the construction requirements of subgrade filling in area 93.(2)Firstly,the modification mechanism of cement and lime and the thermal yield of hydration were analyzed theoretically through referring to relevant data.Then,the loss law of water consumption of cement and lime was studied through laboratory experiments,and the empirical calculation formula of water consumption of quicklime improved soil was obtained,and its reliability was verified.(3)Through a large number of laboratory tests,the change rule of physical and mechanical properties of granite residual soil under different dosage of modifier and reaction time of modifier was studied,and the optimal amount of modifier and the time of paving and rolling were determined on the premise of considering project cost and ensuring construction quality.(4)Through the transformation of compaction work of soil sample and compaction energy of roller vibration,the transformation relation between compaction degree and construction equipment is established,and the mathematical expression of loose spreading thickness and compaction number is obtained.The technological parameters of the improved construction of the granite residual soil modified soil subgrade were determined,and the filling process parameters of the airport road subgrade were obtained by taking the cement final setting time as the control parameter.(5)The stress deformation of the modified road under standard axle load is analyzed by using finite element software,and the thickness of the improved road embankment is determined by analyzing the value of the deflection on the top of the roadbed under different thickness of the improved embankment.The simulation analysis of the force and deformation of the road under the effect of different lanes and different vehicles is carried out,which provides some guidance for the use and design of the road.