Abstract of Special Research Report (SRR-No.35)
National Institute of Occupational Safety and Health, Japan
Safety for Construction of Small-to-medium Sized Excavation Using Observational Procedure
Introduction
SRR-No.35-1 |
Yasuo TOYOSAWA |
: Accidents due to slope failure frequently occur at excavation sites. About 20 workers die annually in accidents attributed to slope failure or rock fall during slope-cutting work in Japan.
Keywords;Slope failure, Labor accident, Excavation, Slope-cutting work, Construction work |
Analysis of Labor Accidents Caused by Slope Failure During Slope-cutting Work
SRR-No.35-2 |
Kazuya ITOH, Yasuo TOYOSAWA and Noriyuki HORII |
: Accidents due to slope failure frequently occur at excavation sites. About 15 to 20 workers die annually in accidents attributed to slope failure or rock fall during slope-cutting work in Japan. Study of such accidents from 1989 to 2002 was carried out and found that about 131 fatal accidents occurred due to slope failure and rock fall. Analyses of such accidents were done to recommend effective countermeasures for reduction of such accidents. The profiles of the slope failures were studied and classified by various factors, such as geology, type of construction works, slope height, gradient, scale of failure, and rain fall conditions, etc. These factors were investigated and analyzed in this research and following summary is made.
Keywords;Labor accident, Slope stability, Slope-cutting work |
Stability of Trench Excavation Under Construction Machinery Load
SRR-No.35-3 |
Yasuo TOYOSAWA, Kazuya ITOH and Junjie YANG |
: There are many labor accidents in which the workers are killed and buried under collapsed ground when the construction machinery such as a drag shovel falls or topples over the edge of the trench during excavation. Based on the labor accident reports, during the period of 1994 to 2002, there were approximately 30 workers killed every year in Japan due to this type of failure. To prevent the loss of life and injury caused by the ground collapse, it is necessary to gain more understanding about the effect of construction machinery load, geometry of ground excavation (e.g. slope angle and excavation depth) and characteristic of ground strength on the stability of trench excavation.
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Experimental Analysis on Shallow Failure of Slope in Consideration of Relationship between Ground Permeability and Precipitation Intensity
SRR-No.35-4 |
Satoshi TAMATE, Naoyuki ITOH and Akira ENDO |
: Rainstorms frequently induce slope failures that take a lot of lives and destroy many social assets. Recent increases in both the amount of rainfall and the intensity of precipitation cause severe damages in Japan as well as other countries throughout the world. In particular, heavy rain events induce shallow failures in slopes within short durations. Therefore, the risk of failure must be analyzed in particular sites to reduce losses and save peoples lives. However, preliminary evaluations are not conducted well because simple methods of analysis are not well considered. |
Stability of Shotcreted Slope During the Maintenance
SRR-No.35-5 |
Kazuya ITOH, Yasuo TOYOSAWA, Masafumi SUZUKI and Naoaki SUEMASA |
: The maintenance of slope stabilization constructed during the rapid economic growth period of Japan (1955-1973) is increasing in recent years. In that period, most of the slope stabilizations were done by shotcrete, which can protect the slopes from water intrusion and erosion. Every year, some accidents take place during the maintenance of such shotcreted slopes. Hence, it could be said that such type of labor accident might increase from now onward. |
Physical Modelling of Slope Failure During Slope Cutting Work
SRR-No.35-6 |
Kazuya ITOH, Yasuo TOYOSAWA, Surendra B. TAMRAKAR,Sahaphol TIMPONG and Noriyuki HORII |
: Excavated slopes become safe only when they are either excavated to a safe slope angle orwhen protective measures are taken. During slope cutting work, slopes are at greater risk of failure. In many cases, slope failure suddenly occurs without any warning signs and the workers do not have time to escape and hence accidents take place. In Japan, there are about 30 to 40 slope failure accidents every year, causing casualties among workers and damage to property. More than 50% of such accidents occur during excavating or leveling the lower parts of the slope toe. To prevent such accidents, the mechanism of slope failure caused by slope cutting work should be clarified. |
A Study on Prediction of Slope Failure Using Highly Accurate Tilt-Sensor
SRR-No.35-7 |
Yasuo TOYOSAWA, Kazuya ITOH, Surendra B. TAMRAKAR, Takaaki ARIKI, Takashi KUNIMI, Atsushi NISHIJYOH, and Satomi OHKUBO |
: Sudden failures of slope during or just after slope excavation works cause many serious accidents which sometimes take the lives of workers. Loss of lives and property damages could be prevented if early predictions of failure could be made. Although many instruments have been developed to measure the movement of landslide, however, most of them are either difficult to set up or are too expensive to use at small to medium-sized slope excavation sites. In this study, a simple and costeffective slope monitoring system using the tilt-sensor was developed, and the mechanism of slope failure was also investigated. |
Development of the Short Pipe Strain Transducer (SPS) Comprising a Screw End and Experimental Analysis on its Applicability for Safety Monitoring in Slope Works
SRR-No.35-8 |
Satoshi TAMATE and Akira ENDO |
: Slope failures frequently cause labour accidents in construction sites. It is also known that even a small collapse can cause serious injury to workers. In particular, vertical cuts at the toe of slope are carried out to build retaining walls for expansion of load width, and unstable slopes appear even short term. Slope failure must be avoided for safety. Consequently, temporary constructions are needed to support slopes. However, this process is sometimes omitted because of difficulties resulting from a lack of sufficient lateral reaction force. Since many slope works are going on, finding methods are needed to ensure safety for workers in slope works. One of the solutions considered is the provision of a warning system that provides the time required to escape through accurate monitoring. A slip surface appears at slope failures, and then major deformations develop along the slip. However, shallow deformation arises at the same time even though higher sensitivity is required to measure its small values. The Short Pipe Strain transducer (SPS) was developed, and then its applicability was investigated by Centrifuge model tests and Prototype model tests. It is compact in size with a length of 1m and a diameter of 15mm. SPS outputs the strain based on the response of bending deformations. Since the SPS penetrates by itself without pre-borings, installation into ground is easily conducted by a hand operated drill. Moreover, SPS strongly contacts with surrounding soil and this contributes to high sensitivity. |
Development of a Monitoring and Alarm System for Slope Failure Using a Laser Beam and Optical Sensor
SRR-No.35-9 |
Kazuya ITOH, Yasuo TOYOSAWA, Minenori TAKEYAMA and Tetsuya SANO |
: Accidents due to slope failures frequently occur at excavation sites. In Japan, approximately 20 workers are killed each year by slope failure or rockfall during slope cutting work. Lives could be saved and damage reduced if early warning of slope failure could be made. Although many monitoring instruments for landslides have been developed to measure the movement of the slope just before failure, most of them are either difficult to set up in the field or are too expensive to use in small- to medium-sized slope cutting sites. To prevent accidents due to slope failures, it is necessary to develop a system for monitoring small- to medium-sized slope cutting sites. |
Labor Accidents Caused by Slope Failures and Preventive Strategies
SRR-No.35-10 |
Yasuo TOYOSAWA and Kazuya ITOH |
: In Japan, slope failures have caused a number of fatalities and economic loss throughout time. Most of the human-induced slope failures occurred due to the destabilization of slope when the lower part of a natural slope was removed or the slope was steepened during construction works.
Keywords;Labour accident, Excavation, Slope failure, Slope-cutting work |