Title: European empirical methods applied to subsidence in U. S. coal fields
Abstract: The empirical methods commonly used in Europe to describe the shape of subsidence troughs are tested against the field data of the York Canyon Mine in Northern New Mexico. This mine is in a flat lying seam under rugged terrain. The subsidence data consists of time-correlated measurements of surface displacements above two longwall panels. While the profile fits from the graphical methods (United Kingdom) do not agree with the measured profiles, the profile functions of the error integral type used in Continental Europe fit the data well. The profile function analysis of the development curves also suggests a time-dependent response of the overburden. These results, except for the specific profile function used, are similar to those found previously for longwall subsidence at the Old Ben No. 24 Mine. Parameter values of the fit, i.e., the effective half range of the function and inflection point offset, were determined for all profiles. These parameters for the development curves and traveling profiles, which fundamentally result from the same raw data, exhibit markedly different apparent ''scatter.'' The rather narrow range of values for the development curves suggest that individual points subside in a well-behaved manner; and hence, the large variation in parameter values for the traveling profiles reflects an inadequacy in the analysis in correlation between points. Consequently, the use of influence functions appears to be a possible method for improving the empirical analysis of longwall subsidence.