Subsidence Mitigation Using Void Fill Grouting

摘要: Void fill grouting is a technique which has been extensively used by CTL/Thompson, Inc. to mitigate mine subsidence potential resulting from abandoned underground coal workings. The involves rotary drilling the surface down into workings and pressure injection of grout voids rubble zones voids. Communities Rock Springs, Glenrock Hanna, Wyoming were built over mines. Over time, rock comprising roof begins fracture collapse open mine. This process continues until space either occupied or caving reaches surface, threatening public health safety. To successfully reaching thorough understanding mechanism required proper mitigation method selected. paper describes typical mechanisms methods. depth mining important when determining whether not will reach surface. Also are; thickness mined seam, bulking . characteristics strength overburden rock. information can be obtained investigative drilling, laboratory testing on material samples careful analysis. presents brief descriptions analytical methods determine critical depth. Once determined, pilot program undertaken optimal hole spacing for mitigation. During construction, holes are drilled grid as determined in low injected through drill Critical items during sequence, slump variation, pressures, cutoff quantities verification drilling. this Springs Glenrock, 13 years with construction costs exceeding 35 million dollars. Verification lack insurance claims surficial features indicate that void an effective effects due