Prevention of ground subsidence through excavation work

• Drilling work: The excavation depth is 4 meters or more below the ground surface and the excavation area is 500 square meters or more
• Tunnel construction: Finished inner diameter of 1.35 meters or more and extension of 100 meters or more

Pamphlet (land subsidence and excavation work-regulation by excavation work-) (PDF: 301KB)

Notes

1. The excavation area of the excavation work shall be the projected area.
2. The extension of tunnel construction includes shafts.
3. If the tunnel shape is other than a circular shape, it is applicable if any of the completed cross-sectional shape of the tunnel is 1.35 meters or more.

About the following reports, we can perform in Yokohama-shi electronic application, report service (outside site).

registration form (No. 29 style) (Word: 16KB)
Guide (Creation of excavation work in registration form) (PDF: 789KB)

Businesses that fall under the above excavation scale (construction contractor) must notify us at least 30 days before the start of the excavation work (in the case of excavation).

1. Name or name and name of representative in case of Address and corporation
2. Location where drilling work is performed
3. Outline of drilling work (excavation area, drilling depth, construction type and construction method, construction period of underground part)
4. Other matters specified by rules (measurement plan for changes in the surrounding ground, excavation floor plan, excavation cross section, excavation longitudinal section)
5. attached documents A) Guide map, (a) soil survey materials, c) structure outline, construction) Reason for selection of excavation method (including auxiliary method), o) process schedule

Notes

1. In the measurement plan for changes in the surrounding ground, etc., describe the measurement items, frequency, location, management standards, management system, and response in case of abnormality.
2. "Excavation method" refers to the method of retaining the mountain in the case of excavation work, and the method of excavation (shield, NATM, propulsion method, etc.) for tunnel work.
3. "30 days before the start of excavation work" refers to the earlier of the construction of a retaining mountain or digging up the ground.

Drilling work change registration form (No. 30 style) (word: 28KB)

• Changed to the contents of the notification and item 1 of attached documents: Please notify us within 30 days from the date of the change.
• Changes to the contents of the notification and items 2 to 4 in attached documents: Please notify us at least 30 days before the date of the change.

Completed drilling registration form (No. 31 style) (word: 13KB)

When the excavation work is completed, please notify us within 30 days from that date.

1. When planning excavation work, select a construction method that has high water stopability and minimizes the impact on the surrounding ground and groundwater level.
2. If there is a risk of collapse of the ground, collapse of the ground surface or subsidence during excavation work, select an appropriate auxiliary method in advance to stabilize the ground.
3. During excavation work, try to detect abnormalities not only in the excavation premises but also in the surrounding ground and structures at an early stage, and observe groundwater levels, ground changes, etc. (Please keep the recording of variable observations for 3 years.)
4. In the event that land subsidence occurs due to the excavation work, take necessary measures, including temporary suspension of construction.

The mayor may provide necessary guidance and advice to businesses that perform excavation work to prevent land subsidence, and recommend that necessary measures be taken when there is a risk of land subsidence (when it occurs). There is.