Date of Graduation
2003
Document Type
Thesis
Abstract
Tensioned bolts work in different mechanisms from the fully grouted resin bolts and are believed to be effective for certain types of roof strata. A 3-D finite element model using ABAQUS has been developed for the tensioned bolting design. In this model, the physical process of the tensioned bolting including entry excavation sequence, roof bolting components, bolt installation procedure and pre-tension is modeled realistically. Bedding planes and in-situ horizontal stresses are also considered in the model. A case study of a well-instrumented intersection of entry/crosscut was used to compare the results from the modeling with field measurements in terms of the vertical stress in the pillars, roof horizontal stress, bolt loads, roof displacement, bedding plane separations and roof yielding. It is concluded that the results from the modeling agree fairly well with the fielding measurements. Using the established model, the bedding plane study is conducted in terms of the its mechanical properties and behavior as well as the effect of the bedding plane location, the number of bedding planes in the immediate roof and the strength sequence of immediate roof on roof stability and tensioned bolting. Factors such as in-situ horizontal stress, overburden depth, longwall mining and intersections are also studied on how they affect the roof stress distribution, roof yielding, roof deformation and tensioned bolting. Based on the analysis of the mechanisms of the tensioned bolts and the failure modes of the tensioned bolted strata, a design procedure for tensioned bolting is proposed. The developed model can be used for tensioned bolting design to determine the bolt length, optimum pre-tension, bolt diameter and bolt spacing. According to the bedding plane locations, the roof is classified into 4 types. Based on the geological condition of the Pittsburgh seam, some design guidelines are given. Finally, a computer program is developed for tensioned bolting design using the data from numerical modeling. The program first gets the geological inputs from users, searches the design information in the database, performs the analysis using the design criteria, and finally displays the design by 2-D/3-D views.
Recommended Citation
Zhang, Yunqing, "Three-dimensional numerical simulation and design of tensioned roof bolting for underground coal mines." (2003). Graduate Theses, Dissertations, and Problem Reports. 10099.
https://researchrepository.wvu.edu/etd/10099