(41C/CV/CX) Analysis of Bank Stability …

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An extract from Analysis of Bank Stability in the DEC Watersheds, Mississippi, U.S. Army (European Research Office), AD-A189 421 (DAJM 45-87-C-0021), JUL 1987.

1.3 Development of Bank Stability Theory
Most of the theoretical analysis was already completed prior to my being awarded this contract, and was presented in the original proposal in appendices B and C. … The theory and applications are set out in detail in papers accepted for publication in the Journal of Hydraulic Engineering of the ASCE (Osman & Thorne, 1988; Thorne & Osman, 1988) …
The computations involved in the analysis are relatively straight forward, but still present numerous opportunities for arithmetic errors. Also, correct interpretation
of the output of the stability model demands some prior knowledge of stability theory. Therefore, I have written a program for the Hewlett-Packard HP-41C calculator which prompts for the required data, performs the analysis, presents and interprets the results, and directs the user to the next computational step. This program requires no prior knowledge of the HP-41C and can be used on site as the calculator is battery powered. The user manual gives complete instructions for the analysis of steep streambanks subject to erosion and bed degradation. A copy of the user manual is attached in Annex 1 …
… This manual provides a calculator program for the Hewlett-Packard HP-41CV or CX calculator, which may be used on-site for application of the Osman-Thorne analysis. The HP-41C may be used provided that it has a quad memory module fitted.
This Users Guide explains how the program is used to calculate the factor of safety for an existing bank, and how to find the amounts of flow erosion and bed degradation which would cause the bank to fail. The bank height, tension crack depth, failure plane angle, block width, and block volume for slab failure are computed. These parameters define the amount of top bank retreat, the volume of slumped material input to the channel, and the new bank geometry after failure.
No prior experience with the HP-41 is necessary.
APPENDIX 4 -PROGRAM LISTING …
… 1.3 Development of Bank Stability Theory
The theoretical and applications papers describing the analysis of bank stability used in this project. have been scheduled for publication in the February 1988 edition of the Journal of Hydraulic Engineering of the American Society of Civil Engineers …
The program for the HP-41CV calculator has been debugged and extensively tried and tested for accuracy. Minor changes have been made to the program to eliminate bugs and to improve its computational efficiency. A new program has been written, to analyse subsequent failures due to basal clean-out of the initial failure, and further lateral erosion or bed degradation. The revised and expanded program is listed in Annex 1. A revised users' manual is in preparation …
ANNEX 1:
BANK STABILITY PROGRAM for HP 41-CV
SUBSEQUENT FAILURES PROGRAM

replete w/ flowcharts, etc …

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