Innovation and development from bedding separation grouting to overburden isolated grouting
摘要
The mining of coal under buildings has always been a major technical challenge for coal mines. To address this issue in China, the bedding separation grouting subsidence reduction experiments were carried out from the 1980s in about 10 coal mines, achieving certain results. However, since the actual subsidence reduction rate did not meet the requirements for building protection, the technical feasibility of mining coal under buildings through bedding separation grouting was questioned and gradually abandoned. Based on the key stratum theory of strata control and the full-stratigraphy academic thought, the overburden isolated grouting technology was developed. It was first successfully applied in Huaibei mining area in 2009, solving the problem of mining coal under buildings. Its application scope, scale, and fields have been continuously expanding. Currently, the enthusiasm for overburden isolated grouting is on the rise. To promote the healthy development of the industry’s technology, it is necessary to scientifically review and comprehensively examine the development process, and clearly define the differences at the theoretical and technical levels. This innovations of overburden isolated grouting in theory, technology, and practice are systematically discussed. At the principle level, it clearly shifts the technical essence from the “searching for bedding separation” of bedding separation grouting to the “compaction grouting” of isolated grouting, firmly establishing the correct guiding ideology and theoretical direction. From the perspective of the cumulative effect of unloading and expansion of the overburden due to mining, it is found that the bedding separation is suppressed, and the maximum amount is usually less than 10% of the mining height. In some conditions, there is even no bedding separation. Bedding separation grouting focuses on the “bedding separation space” and fills it, which has been proven to have a small filling volume and a low grouting-to-m