Application Of Huaibei Coal Gangue In Highway Subgrade

Coal gangue is a kind of rock which emerged with coal bed, and is separated out as a waste during the processes of coal mining and washing. With the mining of coal, a large number of coal gangue has been piled up around the mining area because of its low utilization rate, and formed coal gangue pile eventually. The exposed coal gangue pile takes up a lot of land and it’s easy to have self-ignition and release harmful gases. Under the influence of rainfall, it also can release the heavy metals which can pollute the soil and surface water. On the other hand, the high grade highway needs a large amount of filler materials. The use of coal gangue in the construction of subgrade can not only reduce the accumulation of coal gangue pile, save land and mitigate environment pollution, but also can reduce construction cost, and has good economic and social benefits.Based on the S203 project of HuaiBei city, the following research was proceeded:(1) Based on the subgrade related specifications and characteristics of coal gangue, the requirements of technical index was proposed when the coal gangue is used as highway subgrade;(2) The characteristics of huaibei washed coal gangue physical, chemical and engineering was researched through laboratory test, and analyzed the applicability of coal gangue as filler, then compared with other regional coal gangue;(3) A series of research were carried on, such as the law of freeze-thaw damage of coal gangue, the influence of P5 content to the compaction characteristic, permeability characteristic and bearing capacity, the relation between compaction work with crushing rate and dry density, the influence of adding soil to the compaction property, the compression property and the bearing performance of coal gangue is studied;(4) Through the test road, studied the settlement regularity of uncompacted layer gangue after static pressure and vibration pressure, and determined the gangue roadbed construction technology and quality control points;(5) Analyzed the techno-economics when coal gangue was used in subgrade construction. The results of the study show that, Huaibei washing coal gangue can meet the subgrade engineering requirements, and the relationship of maximum dry density, optimum moisture content, CBR and permeability coefficient is obtained through the analysis of the laboratory test data, and the best P5 content and soil content is determined. The gangue subgrade’s effective is proved by the field compaction test, and the method of construction quality control is proposed eventually.