In Situ Sampling and Aechanical Performance Testing of Filling Materials in Goaf
In order to understand and master the mechanical properties of the filling material in a large molybdenum mine goaf,samples were collected from large volume filling materials in different goafs as the research object.The geological drilling sampling method in the field of geotechnical engineering was used,and various performance tests were carried out using equipment from the enterprise′s on-site laboratory to analyze the strength and deformation characteristics of the filling material in different goafs.The results indicate that there are certain differences in the properties of filling materials in different mining sites,and even filling materials in different parts of the same min-ing site sometimes have significant differences in their properties.Through detailed on-site geological investigation and sample description,as well as mechanical performance testing of 45 filling specimens from 6 mining sites in the middle section of 835 m and 795 m,the strength range of the filling specimens in the 6 mining sites of 2701#,3107#,3903#,2304#,2306#,and 2702#was determined to be 2.387～9.204 MPa,0.370～7.273 MPa,0.915～4.121 MPa,1.459～17.208 MPa,1.471～17.778 MPa,and 0.308～3.509 MPa,respectively.Analysis shows that the reasons for the differences in filling properties are multifaceted,as the spatial distribution of particle size distribution and mineral composition varies with the process conditions in the goaf.Changes have occurred,resul-ting in different processes of settlement and solidification hardening of the filling slurry.At the same time,the seg-regation of the filling cementitious material has also had a significant impact on the local properties of the filling body.In response to the actual situation of uneven distribution of filling properties in goaf,in order to prevent the occurrence of large-scale collapse of filling caused by mining blasting vibration,and to ensure that production per-sonnel,mining equipment,and underground structures are not harmed,a two-step mining process was adopted by dividing mining into 2～3 sections.Based on on-site observation,the intact rate of filling can be basically con-trolled at around 85%～90%,thereby maximizing the integrity and stability of filling throughout the entire mining process.
filling body in goafin situ samplinggeological featuremechanical testingdisaster prevention and reduction
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