Study On Calculation Of Subgrade Permanent Deformation Based On Non-uniform Distribution Of Modulus Under Humidity And Driving Load

Under the background of continuous rapid development of China’s economy in the past 40 years,China’s road industry has achieved rapid development.However,in the process of rapid development,a series of problems such as low actual service life of roads,deviation between operation capacity and design expectation and so on are gradually highlighted.This article based on the Hunan-Jiangxi region area highway field investigation and relevant test showed that due to the impact of hot and humid climate environment,heavy and concentrated rainfall,abundant groundwater,roadbed construction was seriously wetted after completion,resulting in the decrease of the stiffness,strength and stability of the subgrade structure,significantly increasing deformation and then under the effect of overloading or overload transportation,the roads suffer from pavement rut,reflective cracks and other problems frequently.Therefore,the study on the permanent deformation of subgrade under the action of humidity and traffic load is of great significance to improve the durability of subgrade and pavement.However,the modulus and deformation of subgrade are significantly dependent on stress and humidity,resulting in the non-uniform spatial distribution of the modulus of each point inside the subgrade.At present,there is little research on the calculation of the permanent deformation of subgrade considering the non-uniform distribution of the modulus inside the subgrade.The main efforts are as follows:(1)To reveal the change rule of the subgrade humidity with the changes of local climate environment,in this paper,the typical clay of high liquid limit in the south was used as subgrade filler,and a numerical calculation model of subgrade humidity was established by Geo-studio software for numerical calculation of humidity.The non-uniform distribution of subgrade humidity field was obtained.The subgrade humidity gradually increased after the completion of the highway,and reached a balanced state after 4-13 years;(2)In order to optimize subgrade design,based on the non-uniform distribution of subgrade humidity field,a method for calculating the non-uniform modulus field of subgrade was proposed by using Matlab software in combination with Geo-studio and Abaqus software.The non-uniform modulus field of the clay of high liquid limit subgrade was obtained through an application example,and the method and the numerical model of the modulus were effectively verified.(3)In order to more closely consider the depth of subgrade work area on the site,and thus reduce the difference between design and construction,the research on the evolution law of the depth of subgrade work area at different overload,pavement thickness and operation time was carried out under considering the non-uniform distribution of the modulus of each point in the subgrade structure.(4)In order to predict the permanent plastic deformation of subgrade soil more accurately,a calculation method of permanent deformation based on spatial non-uniform distribution of subgrade modulus was proposed and applied in an example.