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U.S. Department of Energy
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Subsidence prediction for the forthcoming TONO UCG project. [Rubble model and block model]

Conference ·
OSTI ID:5952248

The motion of the strata that overlie the TONO UCG Project partial-seam test is calculated using the analyses that have been developed for the prediction of subsidence above coal mines. This purely mechanical analysis of the overburden response to the formation of a void in the underlying coal seam is based on the analysis of two codes. The first is a finite-element code that uses a nonlinear rubble model to describe both the kinematics of roof fall and the continuum behavior of broken and unbroken strata. The second is a block code that treats the overburden as an assemblage of blocks. The equations of motion are solved for each block using an explicit integration operator. As both of these calculations are two-dimensional in nature, they are used to calibrate the semi-empirical, complementary influence function model. This model permits the extension of the two-dimensional analyses to three dimensions by using computationally efficient algorithms. These techniques are calibrated to UCG projects by analyzing the Hoe Creek 3 burn. Their application to the TONO project required the estimation of the lateral extent of the cavity for the partial-seam test. The estimates utilized the projected tons of coal to be removed and two scenarios for the burn sequence. The subsidence analytical techniques were combined with the expected patterns of coal removal to place an upper bound on the surface subsidence that can be anticipated at the TONO UCG site. 9 figures.

Research Organization:
Sandia National Labs., Albuquerque, NM (USA); Brigham Young Univ., Provo, UT (USA)
DOE Contract Number:
AC04-76DP00789
OSTI ID:
5952248
Report Number(s):
SAND-83-0992C; CONF-830827-2; ON: DE83015209
Country of Publication:
United States
Language:
English