| Case Name |
The result in the execution of the public sewerage business which the earth retaining works has not been constructed because of the insufficient supervision. |
| Pictograph |
|
| Date |
1997 |
| Place |
The Ofunato town in Ofunato City, Iwate Prefecture. |
| Location |
The sewerage construction field. |
| Overview |
Government subsidies \ 3263,000 which concerned this were considered unreasonable since a part of the earth retaining was completely not constructed in tubes laying construction and earth retaining works. |
| Incident |
The earth retaining works consist of sheet piles and so on built up to prevent collapse of cut land when sewage pipe is laid after the excavation by backhoes, etc. And in the city, the decision of the type of earth retaining works shall have been based on "the construction work public accident prevention countermeasure guideline" which Ministry of Construction has instituted.
According to the countermeasure guideline, the type of the earth retaining works shall be decided considering excavation depth, soil condition, environmental condition, etc..
Then, earth retaining works using wooden sheet pile would have been constructed in all construction zone ( total 498.1m ) such as the tube laying construction, in order to ensure the safety of the construction based on the countermeasure guideline, since the situation of construction zone of this was as follows.
(a) It had been set that earth retaining works should be constructed as a principle, when the excavation depth is over 1.5m, and excavation depth of this case was 1.52m to 2.19m.
(b) Soil property was rudaceous or gravel mixture clay with the possibility of collapse.
(c) There is the possibility of labor accident and public disaster involving general traffic, etc., since the working space was narrow and cut land collapse might occur by vibration of heavy machinery backhoe, etc.
When it was examined it was found that the earth retaining works has not completely been constructed in inside 252.5m of all construction zone total 498.1m in the execution of tubes laying construction, etc.. |
| Sequence |
the Ofunato City, Iwate Prefecture carried out the tubes laying construction, earth retaining works, etc. at the 1997 fiscal year at \ 53413,500 ( government subsidies \ 26706,750 ) construction expenses to construct sanitary sewer conduit, etc. as part of the public sewerage business in Ofunato town Azamyoujinmae district in the city.
In the city, this case construction expenses was calculated including the cost needed for the construction of earth retaining works, and materials and structure of earth retaining works, etc. were clarified for the contractor in drawing and specification, and the construction is imposed in all construction zones such as the tube laying construction.
The contractor submitted the construction plan to the city in which they would construct earth retaining works on all construction zones.
Government subsidy considerable amount \ 3263,000 which concerned this was considered unreasonable without constructing the imposed earth retaining works in order to ensure safety in part. |
| Cause |
The construction imperfection. |
| Countermeasures |
Sufficient supervision by the owners. |
| Knowledge Comment |
The contractors absolutely must not omit the construction. The owners must supervise the omission in construction. |
| Scenario |
| Primary Scenario
|
Poor Value Perception, Poor Safety Awareness, Malicious Act, Ethics Violation, Possible Damage, Potential Hazard
|
|
| Sources |
The 1998 fiscal year settlement inspection report ( Board of Audit ).
|
| Financial Cost |
Government subsidy delivery amount considered unreasonable : \ 3263,000. |
| Multimedia Files |
Fig2.earth retaining works construction plan
|
| Field |
Civil Engineering
|
| Author |
NAKAGAWA, Masafumi (The University of Tokyo)
KUNISHIMA, Masahiko (The University of Tokyo)
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