| Case Name |
The gravel of about 200 cubic meter collapsed at a stretch over about 10m width with earth retaining works which supported it. |
| Pictograph |
|
| Date |
May 22, 1989 |
| Place |
Kawasaki City, Kanagawa Prefecture |
| Location |
The field of "the Nogawa River health center construction" in Kawasaki City. |
| Overview |
In the field of "the Nogawa River health center construction" in Kawasaki City, while the basement was drilled inside the earth retaining works of 12m height which was equipped at three sides of the field and which consisted the soldier beam and breast board, the support timber collapsed and the gravel broke and fell. As a result, there were 7 casualties because of being buried alive. |
| Incident |
At around 13:15 on 22nd May, the first year of Heisei, in the field of "the Nogawa River health center construction" in Kawasaki City, the earth retaining works collapsed over about 10m, and the gravel of about 200 cubic meter fell, and 5 workers died, and 2 workers got injured. |
| Sequence |
* In the scheme of execution, a soldier pile of earth retaining works was to be driven to 3.6m below from the floor.
* The excavation was continued with the situation that most of the soldier pile did not reach the floor. As a result, the lower end of the soldier pile floated up from the floor.
* The soldier pile was carried off its bottom by the earth pressure, and the position of the waling (which was placed in horizontal direction, which supported the sheet pile placed in vertical direction, in order to prevent the soil break during digging the hole underground) was made to be a supporting point, and the bottom of the pile was pushed out. Next, the soldier pile detached from the supporting beam, and the pedestal of the earth anchor dropped off.
* Earth pressure from the back wholly depended on the support timber which became unstable and the support timber fell forward, which caused a massive landslide. |
| Cause |
* In the scheme of execution, it was to strike the soldier pile after digging down the country rock in the field, which was about 9.5 high, until it became 5m high. However, since the soldier pile was struck in spite of the fact that the top of the country rock was dug down only about 1.5m, the soldier pile was not settled sufficiently. (fatal cause)
* The young employee who was in charge of managing the construction had little experience of sheeting construction, and he managed the assembly of the support timber for the first time. This employee did not confirm the assembly figure and the height of the ground when the soldier pile of earth retaining works was placed. Moreover, any countermeasure such as the recommencement of the pile driving was not taken despite it was noticed that chipping of the country rock was insufficiently during excavation. Additionally, despite the indication of the worker who noticed that the soldier pile had been coming up from the floor before earth retaining support timber collapsed, no countermeasure such as discontinuation of work and entrance prohibition was taken.
* The problem of the construction management system of the original contractor was the root factor. |
| Countermeasures |
* In managing the construction, the scheme of execution should be understood sufficiently.
* When noticing a mistake, it should be reported to the superior, the countermeasure should be considered, and it should be responded to at once.
* Be sensitive to hear the report from the worker on the front lines. |
| Knowledge Comment |
* The scheme of execution should be understood sufficiently.
* Mistakes should be dealt with at once.
* Respond positively to the fact. |
| Background |
In this field, because the director served concurrently on several fields, the young employee who had little experience of sheeting construction and assemblied the support timber for the first time was in charge of managing the construction. The guidance management system was insufficient. |
| Reason for Adding to DB |
For preventing the same kind of construction disaster from coming about. |
| Scenario |
| Primary Scenario
|
Misjudgment, Narrow Outlook, Organizational Problems, Poor Management, Ignorance, Insufficient Knowledge, Regular Movement, Wrong Movement, Incorrect Reaction, Poor Communication, Failure, Large-Scale Damage, Bodily Harm, Death
|
|
| Sources |
Measures for preventing a recurrence learning from 70 examples of grave accident - construction accident - , Nikkei Construction
|
| Number of Deaths |
5 |
| Number of Injuries |
2 |
| Physical Damage |
unknown |
| Financial Cost |
unknown |
| Economic Loss |
unknown |
| Consequences |
Construction disasters might cause social distrust of management responsibility of original contractors, and furthermore, it might increase anxiety and distrust of danger at construction site, which the neighboring residents have. |
| Field |
Civil Engineering
|
| Author |
TANAKA, Nobuyuki (Japan Engineering Consultants Co., Ltd.)
|
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