Failure analysis of steel open dam against an extreme boulder debris flow

2020 ◽  
pp. 204141962097056
Author(s):  
Toshiyuki Horiguchi ◽  
Hiroshi Kokuryo ◽  
Nobutaka Ishikawa
Keyword(s):  
Debris Flow ◽  
Failure Analysis ◽  
Safety Assessment ◽  
Distinct Element ◽  
Rigid Wall ◽  
Reduction Factor ◽  
Second Step ◽  
Uniform Load ◽  
Load Model ◽  
Level Ii

This paper presents a failure analysis for a steel open-type Sabo dam (hereafter, steel open dam) against an extreme boulder debris flow load (hereafter, level II load) by a two-step analysis. The first step analysis is to estimate the level II load against the rigid wall by using the revised distinct element method (DEM). In the second step, the failure mechanism of a steel open dam is examined by using a dynamic elastic plastic analysis, in which the level II load-time relations obtained by the first analysis are multiplied by a reduction factor and then used. For the second step, the effects of the flange joint and dent deformation of the connection between column and beam are considered. Finally, a simple entire uniform load onto the steel open dam is proposed as a level II load model for the safety assessment.

Safety assessment method of steel protective structure against large-scale debris flow

2021 ◽  
pp. 204141962110595
Author(s):  
Hiroshi Kokuryo ◽  
Toshiyuki Horiguchi ◽  
Nobutaka Ishikawa
Keyword(s):  
Debris Flow ◽  
Safety Assessment ◽  
Large Scale ◽  
Assessment Method ◽  
Load Level ◽  
Energy Constant ◽  
Level Ii ◽  
Load Carrying ◽  
Torrential Rainfall ◽  
Protective Structures

Recently, steel pipe open type protective structures (steel open dams) have been damaged because of large-scale debris flow resulting from torrential rainfall based on abnormal climate. This article proposes a safety assessment method for the load-carrying capacity of a steel open dam against large-scale debris flow load (level II load) using the energy constant law. First, the safety assessment method of steel open dams is proposed that the ultimate strength must be larger than the required strength against the level II load, which is determined by using the energy constant law. Second, the load-carrying capacities of three types of steel open dams with different structural shapes against the front and eccentric debris flow loadings are investigated by a push-over analysis. Finally, the safety assessments on load-carrying capacities against the front and eccentric debris flow loading are confirmed and the strength reduction by the eccentric loading is examined for three steel open dams.

A Review of Wet Etch Formulas for Silicon Semiconductor Failure Analysis

1996 ◽  
Author(s):  
T.W. Lee
Keyword(s):  
Failure Analysis ◽  
Literature Search ◽  
Wet Etching ◽  
Second Step ◽  
Environmental Concerns ◽  
Acid System ◽  
Graphical Data ◽  
Selective Etch ◽  
Chromium Compounds ◽  
Wet Etch

Abstract WET ETCHING is an important part of the failure analysis of semiconductor devices. Analysis requires etches for the removal, delineation by decoration or differential etching, and study of defects in layers of various materials. Each lab usually has a collection of favored etch recipes. Some of these etches are available premixed from the fab chemical supply. Some of these etches may be unique, or even proprietary, to your company. Additionally, the lab etch recipe list will usually contain a variety of classical "named etches". These recipes, such as Dash Etch, have persisted over time. Although well-reported in the literature, lab lists may not accurately represent these recipes, or contain complete and accurate instructions for their use. Time seems to have erased the understanding of the purpose of additives such as iodine, in some of these formulas. To identify the best etches and techniques for a failure analysis operations, a targeted literature review of articles and patents was undertaken. It was a surprise to find that much of the work was quite old, and originally done with germanium. Later some of these etches were modified for silicon. Much of this work is still applicable today. Two main etch types were found. One is concerned with the thinning and chemical polishing of silicon. The other type is concerned with identifying defects in silicon. Many of the named etches were found to consist of variations in a specific acid system. The acid system has been well characterized with ternary diagrams and 3-D surfaces. The named etches were plotted on this diagram. The original formulas and applications of the named etches were traced to assure accuracy, so that the results claimed by the original authors, may be reproduced in today's lab. The purpose of this paper is to share the condensed information obtained during this literature search. Graphical data has been corrected for modem dimensions. Selectivities have been located and discussed. The contents of more than 25 named etches were spreadsheeted. It was concluded that the best approach to delineation is a two-step etch, using uncomplicated and well-characterized standard formulas. The first step uses a decoration or differential etch technique to define the junctions. Formulations for effective decoration etches were found to be surprisingly simple. The second step uses a selective etch to define the various interconnections and dielectric layers. Chromium compounds can be completely eliminated from these formulas, to meet environmental concerns. This work, originally consisting of 30 pages with 106 references, has been condensed to conform with the formatting requirements of this publication.

Study on Ground Motion Characteristics of River-bed Caused by Debris Flow after an Earthquake Using Distinct Element Method

2019 ◽  
Vol 19 (6) ◽  
pp. 6_272-6_282
Author(s):  
Masayuki YAMADA ◽  
Satoru YAGI ◽  
Koji HADA ◽  
Yoshinori FUJINO ◽  
Sosuke FUKATSU ◽  
...  
Keyword(s):  
Debris Flow ◽  
Ground Motion ◽  
Distinct Element ◽  
Distinct Element Method ◽  
River Bed ◽  
Motion Characteristics ◽  
Element Method

Debris flow interaction with structures: challenges to traditional load models

2020 ◽  
Author(s):  
Alessandro Leonardi ◽  
Andrea Pasqua ◽  
Marina Pirulli
Keyword(s):  
Debris Flow ◽  
Relative Size ◽  
Nonlinear Function ◽  
Field Measurements ◽  
Italian Alps ◽  
Load Model ◽  
Flow Energy ◽  
Load Models ◽  
Maintenance Work ◽  
Flow Through

<p>Debris flow barriers often feature one or more filter elements, i.e. narrow outlets that induce deposition of the coarsest sediments, while allowing water and fines to filter through. Slit dams and steel nets are examples of this type of barriers. The design of the filter elements must balance the need to trap boulders and to dissipate the flow energy, while keeping maintenance work as low as possible.</p><p>Filter barriers elude the traditional load model prescribed by guidelines. Under some conditions, the outlets can clog with large boulders. The time necessary for this to happen mainly depends on the relative size between boulder and outlet, and is a nonlinear function of the flow composition. In any case, the main clogging mechanism is the formation of granular arches. These can induce significant load also in directions different from the main direction of the incoming flow.</p><p>Unless the barrier is specifically designed to withstand this type of load, granular arches, but also prolonged flow through the outlet, can induce deterioration and loss of functionality of the structure. In this work, we estimate these effects employing a combination of discrete- and continuum-based numerical methods. We evaluate the performance of two types of debris-resisting barriers, comparing the results with laboratory measurements and with the outcome of a monitoring campaign on a real barrier located in the Italian alps.</p><p> </p><p> </p><p>References:</p><p>Leonardi, A., Goodwin, G. R., & Pirulli, M. (2019). The force exerted by granular flows on slit dams. Acta Geotechnica, 14(6), 1949–1963.</p><p>Leonardi, A., & Pirulli, M. (2020). Analysis of the load exerted by debris flows on filter barriers : Comparison between numerical results and field measurements. Computer & Geotechnics, 118, 103311.</p>

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