Research On Surface Deformation And Treatment Range Of Highway Mined-out Area

In recent years, with the rapid development of highway construction, which encounter more and more problem of the evaluation and treatment of the mined-out area, how to evaluate the stability for mined-out area become more and more urgent in the transportation construction issues.Combined with " the control technology of highway through mined-out area " of Shanxi Transportation Department, on the basis of extensive investigation for the coal mined-out area in Shanxi Province, the paper firstly has done a systematic study of geological and mining factors of mined-out area for road stability, screened out the main stability-affecting factors, completed system catalog and the choice of level for geologic elements which is the foundation of the stability evaluation standards. According to the results, the paper has given the regression equation of the factors on the surface deformationSecondly,in the evaluation process of highway roadbed stability in mined-out area, in order to solve the numerical calculation problem of the recovery rate parameters, the computing concept of "virtual equivalent mined-out area " is introduced, which is calculated based on physical parameters of the recovery rate. The paper has given the conversion formula between the depreciation rate and the recovery rate parameters which involved numerical contrast calculation through surface deformation of discount calculation with consideration of different reduction rates and different mining thickness of similar conditions of mining area, Furthermore, after applying reduction formula by means of orthogonal experiment on different types arranged calculation program in mined-out area, the results show:lithology is the primary factor controlling ground subsidence, followed by mining deep, recovery rate, ratio of deep to thickness and depth.Thirdly, combined with the calculation results, the paper has given the new criteria, after review of existing evaluation criteria of roadbed stability in mined-out area.1、Plain longwall mined-out area of full extraction conditions (ratio of mining depth and mining width is less than0.8) has significant surface subsidence basin. The ratio of the difference between surface subsidence basin volume and the volume of mined-out minerals is not more than30%; the time of closure mine is greater than2.5H (H is the average mining depth, m) days; and the area is within75m from the basin edge;2、In the room and pillar mined-out area, where the recovery rate is less than30%, the ratio between mining depth and mining thickness is greater than or equal to100. Fourthly, based on different types of reduction calculation for mined-out area, the paper has presented recommended value allowing surface deformation of road construction, so that the numerical calculation of stability assessment with mined-out areas has criterion standards. New criteria has considered different sensitivity of different types of highway structures to subsidence in mined-out areas, which has directly indicated progressive industry standards compared to the old standard. Furthermore with the introduction of "local treatment ","post-maintenance treatment," and other new concepts of treatments, the paper proposed the rectangle scope of treatments, reducing the scope of governance at the premise of quality assurance.Finally, research results has been used in the treatment of mined-out areas projects, such as Huo Yong high-speed way, which reflected the production values.