2022 first-class construction engineer Municipal golden test point foundation pit reinforcement, first-built academic master notes, long press and like + forward + comment continue to be updated, click on my avatar on the Wendang version to send me private message: 2022
① Purpose of foundation pit reinforcement
1) foundation pit external reinforcement mainly is to stop water, and sometimes it can also reduce the active earth pressure that the enclosure structure bears.
[Music formula] Boiled duck outside the pit
2) The main purpose of reinforcement in the foundation pit is: to improve the strength of the soil and the lateral resistance of the soil, reduce the displacement of the enclosure structure, protect buildings and underground pipelines around the foundation pit; to prevent the upward and damage of the soil at the bottom of the pit; to prevent the seepage of the soil at the bottom of the pit; to make up for the insufficient insertion depth of the enclosure wall.
① Soil: strength, lateral resistance, anti-uplift, anti-seepage;
② Enclosure structure: displacement, make up for insufficient depth;
③ Surrounding buildings (structures) and underground pipelines: protection.
② Methods for foundation pit reinforcement
shallow foundation pit: replacement material
Deep foundation pit: cement soil mixing, high-pressure jet grouting, grouting
Permeation grouting: suitable for sandy soil above medium sand and rocks with cracks
split grouting: suitable for low permeability soil layer
High-pressure jet grouting
Not applicable: hard clay soil, foundations containing more blocks or large amounts of plant rhizomes. For soil layers containing too much organic matter, the treatment effect depends on the chemical stability of the consolidated body. The effective treatment length of
is also different. The three-pipe method is the longest, the two-pipe method is the second, and the single-pipe method is the shortest.
rotary spraying form can use any one of the single-tube method, the double-tube method and the three-tube method. The double-tube and three-tube method are commonly used for fixed spraying and swing spraying grouting.
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