1. Setting of leveling base point: based on the principle of ensuring its stability and reliability, the base point should be set on bedrock or low compressibility soil. The location of the leveling base point should be close to the observation object, but it must be outside the influence range of the pressure generated by the building.
2. Setting of observation points: The layout of observation points should fully reflect the deformation of buildings and be determined in combination with geological conditions, and the number should not be less than 6 points.
3. Precision level and molten steel level should be used for measurement. For the first observation object, the measuring tools and timekeepers should be fixed, and the instrument should be strictly calibrated before observation.
4. The measurement accuracy adopts secondary leveling, with the line-of-sight length of 20 ~ 30m and the line-of-sight height not less than 0.3m.
5. Meteorological data should be registered during observation, and the number and time of observation should be determined according to specific buildings. When the foundation pit is deep, the rebound observation after excavation can be considered.
Extended data:
Location of settlement observation point:
1, four corners of the building, four corners of the core tube, large corners and every 10 ~ 20 m or every 2 ~ 3 columns along the external wall.
2, high and low-rise buildings, old and new buildings, vertical and horizontal walls and other two sides of the junction.
3. The differences between the two sides of building cracks, post-poured zones and settlement joints, the buried depth of foundation, the boundary between artificial foundation and natural foundation, the boundary between different structures, and the boundary between filling and excavation.
4. For buildings with a width greater than or equal to 15 m or less than 15 m in complex geological and expansive soil areas, interior wall points should be set in the middle of the load-bearing indoor partition walls, and grounding points should be set in the center and around the indoor ground.
5. Adjacent to the place where heavy objects are piled up, the parts obviously affected by vibration and the culverts under the foundation.
6. Each or part of the frame structure is built on the column foundation or on the vertical and horizontal axes.
7, raft foundation, box foundation slab or foundation structure near the four corners and its central position.
8. Changes in the four corners, foundation form or buried depth of heavy equipment foundation and power equipment foundation, as well as changes in geological conditions on both sides.
9. TV towers, chimneys, water towers, oil tanks, oil refining towers, blast furnaces and other towering buildings. It should be located in a symmetrical position along the periphery intersecting with the foundation axis, with at least four points.
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