Method and practice of quality test after grouting in coal mine goaf

Grouting quality test is the key technology for efficient development and utilization of waste land in the goaf of a coal mine, it is of great significance to evaluate the stability of the site and the safety of construction after goaf management. Based on many engineering practices, this paper summarizes the evaluation method of the qualified standards of the grouting quality and the errors existed in the testing work. The results proved that the quality inspection after grouting is a systematic work. The test method could be optimized according to the characteristics of the construction and grouting design requirements, following the principles of considering both the internal and external work, and keeping the methods consistent and comprehensive detection. The detection indexes were divided into direct indexes(consolidation grouting rate and concrete strength), indirect indexes(permeability, wave velocity and other physical property parameters) and result indexes(deformation value), and core recovery should not be used as a testing indicator. The test indexes and the qualified standards should be determined comprehensively with full consideration of the design requirements of the foundation and the characteristics of the goaf buried depth. When determining the qualified standards of the deformation index, overall consideration should be given to the stability index of the site and the allowable deformation value of the structure. A method for evaluating the grouting quality of goaf was presented, which closely combined the construction process quality control, post-work quality inspection results and the quantitative evaluation of overall grouting effect level. The construction, foundation and goaf of coal mine was regarded as a system, four types of errors in the present detection work were discussed, it has important practical value to evaluate the quality and the effect of underground concealed disaster management.