Design method of side wall depth of foundation pit

A design method and foundation pit technology, applied in excavation, infrastructure engineering, construction, etc., can solve problems such as inability to consider the effect of pre-pressure, failure to find a design method, redundant consumption of resources, etc.

Active Publication Date: 2012-12-26
BUILDING DESIGN RES INST HARBIN INST OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The root cause of the redundant consumption of these resources is: not finding a suitable design method
The main problem is that the effect of preload cannot be considered during the implementation of the operation. Even if the prestressed bolt support is adopted, the effect of the stress on the slip surface of the soil wedge by the applied preload from the row of piles into the soil is not taken into account. Favorable effect, not to mention quantitative calculation and analysis results

Method used

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  • Design method of side wall depth of foundation pit
  • Design method of side wall depth of foundation pit
  • Design method of side wall depth of foundation pit

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Experimental program
Comparison scheme
Effect test

specific Embodiment approach 1

[0033] Specific implementation mode one: as figure 1 As shown, the design method of the depth of the side wall of the foundation pit described in this embodiment is realized according to the following steps:

[0034] Step 1. Calculation formula for the vertical critical depth of the side wall of the foundation pit (the limit depth at which the soil layer can be excavated vertically without enclosure on the side wall of the foundation pit): The natural soil layer τ is given by empirical judgment and experiment f and C value can be calculated by formula (1);

[0035]

[0036] h 0τ : vertical critical depth of side wall of foundation pit;

[0037] τ f : natural shear strength of soil;

[0038] C: cohesion in the soil;

[0039] Soil internal friction angle;

[0040] γ: natural weight of soil layer;

[0041] Note: when the soil layer is cohesive soil, H 0τ =H 0c , with the formula:

[0042] Step 2, the formula for the stress increment generated in the soil by the ...

specific Embodiment approach 2

[0056] Specific implementation mode 2: In this implementation mode, in step 2, the first parameter "3" on the right side of the equal sign in formulas (2), (3), (4), and (5) can be replaced with one of 1 to 3 other values ​​in between. That is, the first parameter on the right side of the equal sign in formulas (2), (3), (4), and (5) takes a value between 1 and 3, which still belongs to the expression range of the corresponding formula. Other components and connections are the same as those in the first embodiment.

Embodiment

[0058] The design uses prestressed anchor rods to carry beams and double piles, one load and one anchor, and it is easy to apply preload to the piles. figure 1 . Steel-concrete pile diameter: 0.4m, pile distance: 1.2m, horizontal distance between anchor rods 2.4m. The soil layer of the foundation pit is plastic and soft, and the triaxial shear test provides: C = 31.09KPa, , r=19KPa / m. The additional distributed infinite average load on the top of foundation pit q=20KPa( ).

[0059] According to the excavation depth h of the foundation pit on site, it can be obtained from the correlation formula △H1 of formula (6) (mean value), the compressive stress increment in the soil behind the pile P=26KPa (the distribution range length is △H1).

[0060]According to formula (1a): HOc=2×31.09 / 19×tg52.71°=4.30m

[0061] According to formula (3): △H1=3 / 19×tg 2 52.71°×26=7.08m

[0062] According to formula (5): △H3=3 / 19×tg 2 37.29°×20=1.83m

[0063] According to formula (6): H=4....

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Abstract

A design method of side wall depth of a foundation pit belongs to the technical field of architectural structures and geotechnical construction. The design method aims at reducing material usage for a row pile supporting structure of the foundation pit and saving cost on the premise of satisfying the reliability of the row pile supporting structure of a side wall of the foundation pit. The method mainly comprises the steps of calculating upright critical depth of the side wall of the foundation pit, providing a formula related to a stress increment of precompression of an anchor bolt or a support transmitted into a soil mass, and a formula of an upright cutting depth increment of the side wall of the foundation pit, and constructing a mathematical model of the upright depth of the side wall of the foundation pit: H equal to H0tau plus delta H1 minus delta H3 greater than or equal to h, wherein the delta H1 is the upright depth increment of the side wall of the foundation pit caused by horizontal compressive stress increment of a soil mass unit; and the delta H3 is the upright depth decrement of the side wall of the foundation pit caused by the vertical compressive stress increment of the soil mass unit. Compared with results of various current design methods of the anchor bolt or support retaining structures, the material usage can be reduced by 50%-80% on the premise of ensuring the reliability of the row pile supporting structure of the side wall of the foundation pit.

Description

technical field [0001] The invention relates to a method for designing the depth of a side wall of a foundation pit, and belongs to the technical field of building structures and rock and soil construction. Background technique [0002] The side wall enclosure of the deep foundation pit is used as a temporary purpose during the construction period, and the amount of materials used is too much, and the man-hour cost is not less than that of the underground foundation project. The construction party is very helpless to these excessive and invalid investments. The root cause of the redundant consumption of these resources is that a suitable design method has not been found. The main problem is that the effect of preload cannot be considered during the implementation of the operation. Even if the prestressed bolt support is adopted, the effect of the stress on the slip surface of the soil wedge by the applied preload from the row of piles into the soil is not taken into account...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): E02D17/02
Inventor 白福波
Owner BUILDING DESIGN RES INST HARBIN INST OF TECH
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