Masters Theses


Bismark Osei


"The lack of metrics to assess clamshell dredge formation dredgeability limits the ability of engineers to predict the dredgeability of compact material and increases the risks associated with clamshell selection. Research is, therefore, necessary to increase our understanding of clamshell dredgeability assessment by evaluating possible metrics that will allow the operator to select the optimal clamshell for the operation. Work done and motor energy are possible dredgeability metrics that can be estimated using micro-processor based machine monitoring. The objective of this work is to test the hypotheses that: (i) work done by the pistons during dredging, by a hydraulically actuated dredge, is a better predictor of clamshell dredgeability than motor energy; and (ii) work done during dredging increases with increasing cycle time.

The first objective of this work was achieved by carrying out field data collection and analysis. The field data (motor current, bucket closing pressure and displacement) was sourced from a 16 yd³ clamshell dredge operating at a mine in Seattle, WA. Work done and motor energy were obtained from the field data. The first research hypothesis was tested by comparing the measure of uncertainty surrounding mean estimates, the coefficient of variation. Kinematics and dynamics models of clamshell dredging were built and validated using the field data. The validated model was then used to test the second research hypothesis.

From this work, it can be concluded that work done is a better predictor of formation dredgeability than motor energy. Also, work done was determined to increase marginally with increasing cycle time. This is a pioneering effort to assess the dredgeability of hydraulically actuated clamshell dredges"--Abstract, page iii.


Awuah-Offei, Kwame, 1975-

Committee Member(s)

Gertsch, Leslie S.
Frimpong, Samuel


Mining Engineering

Degree Name

M.S. in Mining Engineering


University of Missouri Research Board


Missouri University of Science and Technology

Publication Date

Spring 2011


xii, 74 pages

Note about bibliography

Includes bibliographical references (pages 102-107).


© 2011 Bismark Akwasi Osei, All rights reserved.

Document Type

Thesis - Open Access

File Type




Subject Headings

Dredges -- Equipment and supplies
Dredging spoil -- Analysis
Machinery, Kinematics of

Thesis Number

T 9852

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