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A kind of deep foundation pit deformation alarm method

A technology for deep foundation pits and foundation pits, applied in excavation, foundation structure engineering, foundation structure tests, etc., can solve problems such as dereliction of duty, irrational meaning, and disbelief in monitoring results, and achieve the effect of improving safety

Active Publication Date: 2017-07-18
中交投资南京有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In fact, strengthening monitoring cannot be used as a control measure for foundation pit deformation, because problems have been discovered through monitoring, and the alarm has been issued. The meaning of strengthening monitoring is obviously unreasonable. Measures to avoid accident management
This can lead to dereliction of duty, bury safety hazards, and finally lead to major accidents
[0011] In short, there are serious defects in the current method of alarming the deformation of foundation pits.
This kind of alarm work with serious defects has seriously affected the engineering judgment of the site engineer on the safety of the foundation pit; it has made the alarm work useless, causing construction contractors to be accustomed to the alarm, the design unit is helpless, the construction unit is helpless, and the supervision unit turns a blind eye

Method used

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  • A kind of deep foundation pit deformation alarm method
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  • A kind of deep foundation pit deformation alarm method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0039] The main foundation pit of a certain A subway station was constructed in accordance with the method of open excavation. The excavation depth is 16.8m. It is 800mm×1000mm concrete support (9m spacing), and the rest is Φ609×16 steel support (3m spacing).

[0040] It can be seen from Table 2 that the monitoring and alarm values ​​given in the design documents are basically consistent with the national norms ("Technical Specifications for Building Foundation Pit Engineering Monitoring (GB50497-2009)"), that is, the design documents meet the requirements of the national norms.

[0041] Application of the present invention, according to existing specifications and design documents, such as figure 1 As shown, the ground surface measuring point buried at a distance of 9m and 14m from the foundation pit is supported at the fourth level; figure 2 The second support has reached the alarm value, and the foundation pit deformation danger alarm has issued a blue alarm, which has no...

Embodiment 2

[0047] Such as image 3 As shown, the main deep foundation pit of a B subway station is located in the soft soil foundation in the Hexi area of ​​Nanjing. The excavation depth is 19.5m. The ratio is about 0.87. There are 6 supports, the first is 800mm×1000mm concrete support (9m spacing), the rest are Φ609 (t=16mm) steel pipe support, and the horizontal spacing of steel support is about 3.0m. The soil layer of the foundation pit of the station is mainly composed of ②-2b4 layer of soft-flow plastic silty clay and silty silty clay. The thickness of the soil layer is 10.1m-20.1m, and the thickness varies greatly. The soil layer under the floor is ②-3b3-4+c3 silty clay with silt and ②-4b3-4 silty clay, and the thickness of the soil layer is 12.8m~18.9m and 14.5m~28.5m. Long side direction of the station: 10KV electric power 750X500, ΦC200 gas pipeline; ΦC500 tap water pipe; ΦC500~ΦC1000 rainwater pipe; ΦC500~ΦC800 sewage pipe; ΦC500~ΦC1000 rainwater pipe. The short side is the ...

Embodiment 3

[0061] The Hangzhou subway accident foundation pit is 107.5m long, 21m wide, and has an excavation depth of 15.7-16.3m. The design adopts an enclosure plan supported by four φ609 steel pipes on an 800mm thick underground diaphragm wall. The depth of the underground diaphragm wall is 31.5m ~ 34.5m respectively. The west side of the foundation pit is adjacent to Fengfeng Avenue, with heavy traffic and many heavy-duty vehicles. There are many municipal pipelines (including water, sewage, rainwater, gas, electricity, telecommunications, etc.) passing through the road, and there is a river on the east side. floor plan as Figure 4 shown.

[0062]1) According to the existing data, before the accident occurred on November 15, 2008, the maximum settlement was 316mm, exceeding the standard alarm value (9~12) times, and the blue alarm had already occurred. "According to media reports, just one month before the Hangzhou subway collapse accident, cracks were discovered on the road surf...

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Abstract

The invention discloses a deep foundation pit deformation alarm method, which includes the establishment of a foundation pit deformation control index system, and based on the index system, the alarm level is set and alarmed; the index system consists of the accumulated deformation amount, deformation rate and deformation acceleration of the foundation pit Composed of three deformation control key indicators, the cumulative deformation amount and deformation rate have corresponding first alarm values, second alarm values ​​and third alarm values, and the deformation acceleration has corresponding fourth alarm values. The invention can timely and accurately evaluate the safety state of the foundation pit, and improves the safety degree of foundation pit construction.

Description

technical field [0001] The invention relates to a method for alarming the deformation danger of a foundation pit, in particular to a method for monitoring and alarming the deformation of a subway deep foundation pit excavation. Background technique [0002] Subway is one of the important means of transportation to solve the problem of traffic congestion in big cities. The foundation pits of subway stations are generally long and deep. For example, the excavation depth of the foundation pit of the second-floor station of the subway is close to 20m, and the excavation depth of the foundation pit of the third-floor station is 25m. For deep foundation pits in soft soil areas, it is very important to control the deformation of foundation pits due to the large number of nearby buildings. At present, although there are many domestic regulations, such as "Technical Specifications for Building Foundation Pit Engineering Monitoring" (GB50497-2009), "Shanghai Metro Foundation Pit Eng...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): E02D17/02E02D33/00
Inventor 曹雪山张荣宽顾琴
Owner 中交投资南京有限公司