Technology Research Of Classification And Treatment Of Expansive Soil In Wanjiang Economic Belt

The Wanjiang Economic Area was set up as an exemplary area for Anhui Province to undertake industrial transfer.However,the problem of expansive soil has brought about potential safety hazards for the use of roads,civil-industrial construction,slopes,and trunk canals in the study area.Therefore,this paper carried out a series of field investigation work and indoor experiment research under the support of the “Survey and Evaluation of Special Disasters in Anhui Province ” project to improve the treatment of different types of expansive soils in the Wanjiang Economic Area.The main conclusions are obtained.as follows:(1)As far as the sampling of this survey is concerned,the expansive soil in the study area is mostly brownish-brown,mainly composed of silty clay and clay,and mostly contains black iron-manganese nodules.Fissure development is abundant,generally showing a plastic-hard plastic state.98 sampling points were selected in the survey area.Among the samples taken,6 had a free swelling ratio of more than 60% and a maximum of 73.5%.The remaining most of the sampling points had a free swelling ratio of 40%to 60%.(2)According to the difference in swelling strength,three groups of specimens with free swelling ratio of 73.5%,50% and 40.5% were selected for improvement.The modifiers were selected from quicklime,alkali residue and fine sand.The results showed that:(1)When the lime content reaches 6%,the free swelling ratio of the first soil sample is reduced from 73.5% to 20%,and the no-load expansion ratio is 12.5%.The unconfined compressive strength meets the specification requirements;(2)After incorporation of 30% soda residue,the free swelling ratio of the second soil sample was reduced from 50% to 33.1%,and the no-load expansion ratio was approximately 15%,and the unconfined compressive strength peaked at that location.(3)With the increase of fine sand content,the swelling performance of the third group of soil samples was significantly improved,while the unconfined compressive strength was weakened.(3)The effect of wetting-drying cycle on the expansibility and unconfined compressive strength of the three groups of expansive soils showed a similar pattern of change: After the first and second cycles,the water swelling of the soil samples was significant,and the unconfined compressive strength was not affected.The greatest reduction occurs;as the number of cycles increases,the magnitude of this change begins to decay until it stabilizes.(4)The SEM test showed that with the increase in the number of wetting-drying cycles,the micro cracks and porosity in the soil showed an increasing trend;with the increase of lime,alkali residue content and curing age,the hydration products in the soil also increased significantly.The improved soil strength and wet and dry cycle stability have been improved.