Masters Theses

Abstract

"Roof falls in coal mines are the single greatest cause of mining accidents in the U.S. today. For this reason it is imperative that the mechanism of roof failures be identified. An investigation funded by the U.S. Bureau of Mines was initiated in 1970 to determine the factors influencing the deterioration of coal mine roof shale. This thesis was a portion of the investigation that concentrated on the Sahara Coal Company underground mine No. 20 near Marion, Illinois.

The regional geology was studied to determine if geological discontinuities might be an influencing factor on roof falls at the Sahara 20 mine. The study revealed three fault systems and an anticline within the mine operation area. A detailed in situ reconnaissance was made which included observations of the mine geology, operations, ventilation system and back conditions. A laboratory testing program of X-ray diffraction, hardness tests, moisture gain, slaking tests and Atterberg Limits was performed on shale blocks taken from fall areas throughout the operation. To aid in the mine evaluation, environmental continuous- sensing machines were placed in the mine. Also, deflection monitoring stations were located at various places in the mine to record closure.

The laboratory results indicated that the shale throughout the mine was composed of the same elastic minerals and had generally the same clay mineral content ratios. The Sahara 20 shale was found to lose strength with a moisture increase. This shale has a greater affinity for water parallel -with the bedding plane than it has perpendicular. The obtained slaking indices gave artificially high values. The Atterberg Limits identified the shale as a Unified Classification of ML.

The in-situ instruments indicated that as air entered the mine, it increased or decreased in temperature depending on whether it was below or above the constant mine temperature of 60 ° F. The deflection stations indicated sporadic deflection amplitudes but generally closure was indicated at every site. From detailed in situ study the mechanism of slab-type failures -was identified. Also, a roof fall classification system -was developed for the type of falls found in the Sahara No. 20 mine.

It was found from this study that environmental influences were the cause of the major portion of roof falls in the Sahara No. 20 mine"-- Abstract, pp. ii-iii

Advisor(s)

Aughenbaugh, N. B.

Committee Member(s)

Barr, David J.
Grant, S. Kerry
Bruzewski, Robert F., 1918-1978

Department(s)

Geosciences and Geological and Petroleum Engineering

Degree Name

M.S. in Geological Engineering

Publisher

University of Missouri--Rolla

Publication Date

1975

Pagination

xi, 103 pages

Note about bibliography

Includes bibliographical references (pages 98-102)

Rights

© 1975 Marvin E. Adam, All rights reserved.

Document Type

Thesis - Open Access

File Type

text

Language

English

Thesis Number

T 4062

Print OCLC #

5984535

Electronic OCLC #

1484839630

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