A Study On Treatment Technology Of Goafs Under Expressways Using Aeolian Sand

The Yushen Expressway is located in northern Shanxi of China with a total length of 106.974km, which is an important channel to connect three provinces of Jin, Shan and Meng. The expressway overcrosses five mining goafs with a total void volume of 1,029,422m3. The area around the project has a lot of Aeolian sand, thus utilising the Aeolian sand to treat the goafs becomes a potential cheap and feasible method, while the treatment technology of goafs using Aeolian sand in operation is not wellproven yet as no such case study has been done and no experience can be referred to.Based on the treatment project of goafs under the Yushen Expressway, this study investigated in a detail the key technology and construction process by using literature review, theoretical analysis and numerical modeling, field tests and moniroting, induction and summarization, etc. Key technical difficulties were conquered and technical achievements were obtained as follows.(1) Evaluation technology of room and pillar goaf stability. This study epurated a set of evaluation technology of room and pillar goaf stability, by summarizing existed goal evaluation methods worldwide and simulating strata deformation due to mining.(2) Discrete element modelling technology of mining process of room and pillar goafs. This study simulated whole process of mining process of room and pillar goafs including roof fall, overburden trata deformation and bed separation development, and formed a set of effective discrete element modelling technology simulating the whole process of room and pillar mining.(3) Surface drilling, grouting and sand-throwing technology for goafs under expressways. This study investigated a set of effective surface drilling, grouting and sand-throwing technology for goafs including hole-drill, grout producing, grouting and sand-throwing, and hole-sealing,accroding to the features that the project is surrounded by the exaustless Aeolian sand. It is implemented that the Aeolian sand is thrown into the goafs while the grout is injected from ground surface. By improving the construction equipment and skills, it is achieved that the Aeolian sand occupies 50% of total grout in average, which saved a lot of project cost with obvious economic benefits.(4) Quality acceptance technology of goaf treatment:This paper summs up a acceptance technology of goaf treament, which can apply a reference for making relevant standards of goaf in the future based on investigating the domestic acceptance data of goaf treatment and combining the method of goaf treament acceptance underlying Yushen freeway.The success of these research achievements and utilization in the construction played a very important role to achieve the goaf treatment in a safe and fast way with a high quality. It accumulated a rich experience for similar projects in the future, and provided a valuable reference to the treatment of pillar goaf worldwide.