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The gob-side entry retaining technology, one of the scientific mining technical system, can enhance coal recovery rate and reduce entry excavation quantity. However, only the effective entry-side support and the proper entry-in support could guarantee stability of the retaining entry undergoing mining influences of two working faces. In order to recover the section coal pillar between two working faces, the technology is applied in Qinxin coal mine. By using the high-water rapid hardening material as backfill material, the backfill pumps as transportation equipments of the material, the steel formwork and backfill bag as forming molds of the material, the entry-side support is of high support resistance, certain shrinkage, convenient construction. As for the entry-in support, the bolt support is designed to improve the bearing capacity and anti-deformation capacity of the surrounding rock, and the single hydraulic prop is adopted to reinforce roof support. The observation results show that the retaining entry keeps good performance. The case not only brings better economical benefit for Qinxin coal mine but also has referential significance for other coal mines.

The high-moisture quick-concreting material is a special type of cement which can be quick-concreting and full solidifying under the condition of high water cement ratio (2.5 : 1 ) . Thus , the mechanical performances of high-moisture quick-concreting material are as follows : 1) The grout fluidity is better and the penetrability is strong ; 2)The volume of concretion is tiny expansion in favor of solid filling in steel tube and exiguous gap ; 3) Concreting speed is rapid and the early strength is big , and the concreting speed may be also adjusted ; 4)The water cement ratio and the mixing ratio can be changed to meet requirement of different strengths ; 5)There is a good plasticity . The residual strength of concreting body may account for about 50% of the peak value strength if the uniaxial compressive strain reaches to 15% ; 6) As a result of the big water cement ratio , little dosage of the unit volume and low price , the cost for using high-moisture quick-concreting material to reinforce the foundation pit wall and ground base and to fill the steel tube is lower. In this study , the mechanical property and concreting mechanism of high-moisture quick-concreting material to reinforce the loose coal body are studied and analysed by the field test and laboratory test . The test results indicated that there is a notable effect to consolidate roadway , foundation pit wall and ground base by grouting of high-moisture quick-concreting material . Finally , the engineering example of grouting by using the high-moisture quick-concreting material is presented.