| Case Name |
Injury due to the gravel decay |
| Pictograph |
|
| Date |
June 27, 2002 |
| Place |
374 Matsuzaki, Niigata City, Niigata Prefecture |
| Location |
374 Matsuzaki, Niigata City |
| Overview |
The country rock suddenly collapsed under the installation operation of soil pipe VU φ 250 at an excavation point of about 1.9m depth and 1.1m width, and a worker injured his head. |
| Incident |
Since around 13 o'clock on 27th June, the excavation work had been carried out. The work on the floor was finished, and laying and connecting work were being continuously carried out. At around 13:50, two workers were going about the laying and connecting work of the soil pipe VU φ 250 of 4m length and 8kg in weight. When they were trying to connect the pipe, the sand layer of the under side loosened, the upside sub-base decayed, and the worker injured his head. |
| Sequence |
After the workers join the morning meeting and the KY activity from 8 o'clock, they moved to the field as a group of five persons, and they carried out the preparatory work of tools, and then they started digging for laying the soil pipe. At around 11 o'clock, the excavation of 1100 width and 1900 depth and 5000 length was finished without sheeting. The laying of the first soil pipe was carried out. After lunch, at 13 o'clock, excavation of the second pile and the installation of the floor were finished without sheeting, and laying and connecting work were continuously carried out. As it was judged mistakenly that the country rock was strong and was therefore excavated without sheeting, the gravel decays occurred. |
| Cause |
* In the review meeting for the execution scheme which was carried out in the branch and lthe aboratory, earth bracing was to be done in the case of excavating at an angle (about 65 degrees) or digging vertically according to the ground condition, but this was not observed.
* Though the work was carried out as planned at the beginning, the safety consciousness had faded away, and unconsidered work was carried out repeatedly.
* Though the contractor also recognized it as a dangerous work at the beginning, the dangerous work was tolerated as workers became accustomed to it.
* Since the judgement of the excavation angle was left to the foreman of the subcontractor, there was an error of the judgement.
* For the workers, the instruction about the danger of the gravel decay disaster had not been carried out sufficiently. |
| Response |
* The constructon was carried out with sheeting.
* The instruction on the construction work was carried out.
* In the case of work modification (earth bracing or excavation of foreslope), the permission of the contractor is required. |
| Countermeasures |
* The safety instruction was communicated to the party again. |
| Knowledge Comment |
* The work should be carried out as planned. (The plan is not at liberty to be changed.) |
| Background |
* As the reason why the work became easy, it is considered that the procedure was omitted, the effort was saved, and the work procedure was streamlined.
* The manager took a negative attitude towards giving indications and instructions. |
| Sequel |
* The director of the contractor and the field director of the cooperation company were relieved on post.
* The recurrence prevention conference was held and it was telecast on a national network. |
| Account of Concerned Parties |
* It had not been expected that the gravel decays occurred.
* The consciousness of the danger had faded away. |
| Reason for Adding to DB |
To avoid repeating the same mistakes. |
| Scenario |
| Primary Scenario
|
Ignorance of Procedure, Disregard of Procedure, Poor Value Perception, Poor Safety Awareness, Organizational Problems, Inflexible Management Structure, Carelessness, Insufficient Precaution, Non-Regular Action, Change, Bodily Harm, Injury
|
|
| Sources |
A disaster case of our company
|
| Number of Deaths |
0 |
| Number of Injuries |
1 |
| Physical Damage |
0 |
| Financial Cost |
0 |
| Consequences |
There is nothing to be described. |
| Field |
Civil Engineering
|
| Author |
NONAKA, Tadashi (Japan Civil Engineering Contractors' Association)
|
