Study On Road Use Characteristics Of Improving High Liquid Limit Soil With Tunnel Slag

As a kind of special soil widely distributed in southwest mountainous area of China,high liquid limit soil has a lot of adverse effects on engineering construction.With the increasing number of expressways in mountainous areas,it is more and more likely to encounter diseases caused by high liquid limit soil in the process of subgrade construction.In addition,the high liquid limit soil is regional,and its engineering characteristics vary greatly in different areas.Therefore,it is necessary to study and improve the high liquid limit soil,which can provide important reference value for the design and construction of subgrade engineering in related areas.High liquid limit soil is widely distributed along Liyu Expressway in Guangxi Province,which has the characteristics of low strength and poor water stability.In this paper,taking the project as the research background,taking the high liquid limit soil along the line as the research object,according to the local conditions,the research on the road use characteristics of improving the high liquid limit soil with tunnel slag has been carried out,and some positive results have been achieved.The main research contents are as follows:(1)The physical properties of high liquid limit soil in the test area were studied by particle analysis test,chemical composition analysis test and limit moisture content test.Through compaction test,shear test,bearing ratio test,unconfined compressive strength test and static resilient modulus test,the mechanical properties of high liquid limit soil in the test area were studied.According to the literature review and the actual situation of the site,the author puts forward the corresponding improvement method: mixing tunnel slag improvement.(2)In order to study the engineering properties and water stability of the improved high liquid limit soil,it is necessary to mix different proportion of tunnel slag in the high liquid limit soil,and control different degree of compaction for compaction test,direct shear test,bearing ratio test,unconfined compressive strength test and dry wet cycle test.The results show that when the ratio of the improved soil to the tunnel slag is about 15%,the performance of the improved soil can reach the best level,and there is a certain safety reserve.(3)Through Geostudio2018 software,the numerical simulation analysis of 15% tunnel slag modified high liquid limit soil subgrade is carried out.First,based on the limit equilibrium method,the stability of subgrade slope is analyzed,and the safety factor of improved soil subgrade is more than 1,which shows that the improved subgrade slope with tunnel slag is stable and meets the requirements of the code.Based on the method of combined analysis of Mohr Coulomb criterion and effective stress method,the settlement effect of the improved high liquid limit soil subgrade is analyzed.The results show that the subgrade deformation is mainly in the construction period and consolidation period,and the subgrade deformation is small during the use period;the differential settlement of the improved soil subgrade is small during the use period,which meets the design requirements.(4)The construction technology of road use characteristics of improving high liquid limit soil is studied through field test.Through the research on the rolling technology of high liquid limit soil subgrade in the test section,the appropriate rolling times are found to solve the problem that it is difficult to compact the high liquid limit soil improved with tunnel slag;through the settlement observation of the section in the test section,t the appropriate rolling times are found to solve the problem that it is difficult to compact the high liquid limit soil improved with tunnel slag...