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Process for protecting existing piers on two sides in tunnel construction

A technology for tunnel construction and bridge piers, which is applied in the direction of bridges, bridge construction, bridge parts, etc. It can solve the problems of easy leakage of foundation pits, unbalanced stress on structural pile foundations, and untimely pouring, so as to prevent deformation and leakage of foundation pits , increase the overall stability, increase the effect of its own stiffness

Active Publication Date: 2020-06-19
CCCC THIRD HARBOR ENG
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The lateral displacement of the soil will lead to additional bending moments and deformations of the piers and pile foundations, which may cause the displacement of the pile foundation, the reduction of bearing capacity, and even the fracture of the pile foundation in severe cases.
[0003] For the tunnel construction of deep and medium passages, the excavation of the tunnel near the pier leads to an increase in the soil pressure difference between the inside and outside of the surrounding pile; Insufficient support strength and rigidity in the foundation pit; sub-section excavation cushion or bottom slab pouring is not timely
These factors will lead to unbalanced stress on the structural pile foundation and excessive horizontal force.
If a temporary cofferdam is directly added, when the cofferdam is excavated, the entire foundation pit of the deep foundation pit is located in the sea area, and the cofferdam is surrounded by water; the depth is large, the maximum excavation depth is nearly 18m, and the temporary cofferdam is located in the sea, the foundation pit Easy to leak; the cofferdam is affected by tidal waves and is easily deformed; affected by typhoon floods, seawater is easily poured into the foundation pit; the pressure of foundation pit enclosure is high, and there are great safety hazards of instability and overturning

Method used

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  • Process for protecting existing piers on two sides in tunnel construction
  • Process for protecting existing piers on two sides in tunnel construction

Examples

Experimental program
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Effect test

Embodiment 1

[0037] Refer to attached figure 1 As shown, in this embodiment, the main protection process steps are briefly introduced.

[0038] In this embodiment, a protection process for existing bridge piers on both sides during tunnel construction includes several bridge piers. When several bridge piers are set, the proposed tunnel is used as the axis, and the bridge piers on both sides of the proposed tunnel are the middle piers. The piers on the outside of the non-adjacent planned tunnel are end piers; the protection process for several of the piers includes the following steps:

[0039]The construction of S1 preliminary enclosure: adopt the enclosure pile of different grades to carry out initial enclosure respectively to intermediate pier and end pier; The intensity of described end pier enclosure pile is less than the grade of described intermediate pier enclosure pile;

[0040] Construction of S2 strengthened enclosure: after the preliminary enclosure, the composite pile and the ...

Embodiment 2

[0048] In this embodiment, the construction of the primary enclosure in the core construction steps is described in detail.

[0049] Specifically, with regard to the construction of the preliminary enclosure in step S1, it is specifically: through the piling process, the construction of the initial enclosure structure for the middle pier and the end pier is carried out by using interlocking steel pipe piles and steel sheet piles respectively.

[0050] In this embodiment, steel sheet piles are used for enclosure at the end where the requirements for bearing strength are small and the degree of interference is small, while for the middle position with high bearing strength and high degree of interference, locking steel pipe piles are used for enclosure , Compared with piling with uniform materials, it saves materials and the selection of piling is more humanized and rational. The steel sheet pile is preferably OZ20A type steel sheet pile to reduce the unbalanced earth pressure w...

Embodiment 3

[0063] In this embodiment, steps 2-3 are further described in detail.

[0064] Specifically, the construction of step S2 to strengthen the enclosure is: to form a cast-in-place pile by drilling and pouring in the locked steel pipe pile near the side of the tunnel to form a composite pile of the locked pile and the cast-in-place pile, and to form a composite pile on the top of the composite pile. It is joined together with concrete crown beams to form a reinforced enclosure.

[0065] In this embodiment, the cast-in-situ pile formed by continuing drilling and pouring in the locked steel pipe pile increases the strength and rigidity of the locked steel pipe pile; when the tunnel foundation pit is excavated, the foundation soil is prone to lateral displacement, and the pile The foundation and abutment must bear additional bending moment and deformation. The setting of composite piles can increase the overall stability of the pile foundation and foundation.

[0066] Further, the ...

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Abstract

The invention discloses a process for protecting existing piers on two sides in tunnel construction. The process comprises a plurality of piers. When a plurality of piers are arranged, a planned tunnel is taken as an axis, the piers adjacent to two sides of the planned tunnel are taken as middle piers, and the piers not adjacent to outer sides of the planned tunnel are taken as end piers; the construction method comprises steps that S1, preliminary enclosure construction is conducted, specifically, preliminary enclosure is conducted on the middle piers and the end piers through enclosure pilesof different grades; the strength of the end pier enclosure piles is smaller than the grade of the middle pier enclosure piles; S2, reinforced enclosure construction is conducted, specifically, composite piles and reinforced enclosures connected into a whole of the middle piers closest to the side of a to-be-built tunnel are conducted; S3, foundation reinforcement construction is conducted, specifically, foundation reinforcement construction is conducted on the bottom of the proposed tunnel structure and between the middle piers and the end piers; and S4, construction of enclosure connectionis conducted, specifically, primary enclosures of different grades are connected to form an enclosure structure which is communicated into a whole.

Description

technical field [0001] The invention belongs to the technical field of bridge pier protection in water conservancy construction, and in particular relates to a bridge pier protection process in tunnel construction. Background technique [0002] The Shenzhen-Zhongshan Passage is another sea-crossing super project in my country after the Hong Kong-Zhuhai-Macao Bridge that integrates islands, tunnels and bridges. The island tunnel project is the key control project of this project. The east artificial island includes 350,000 square meters of island body, 80,000 square meters of weir section cofferdam, 480m of cast-in-situ main tunnel of weir section, 460m of cast-in-situ buried section on island, 395m of There are a total of 1845m of cast-in-place ramps in the open section of the island and in the weir section and on the island. According to the geological survey report, there is a silt layer with an average thickness of 8m and a maximum thickness of 15m near the piers of the ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): E01D19/02E01D21/00E02D5/22
CPCE01D19/02E01D21/00E02D5/22
Inventor 蔡晓男赵辉徐立新莫亚思孙洪春莫日发
Owner CCCC THIRD HARBOR ENG