CN218786853U - Underground excavation pile foundation underpinning system with closely-adhered lower penetrating existing structure - Google Patents

Abstract

The utility model discloses a secretly dig pile foundation underpinning system of passing existing structure under close-fitting, including carrying on the full hall red support of temporary support, applying in the side direction advance support of the secretly dug tunnel, applying in the preliminary bracing under the existing structure bottom plate, built-in underpinning the beam column of the preliminary bracing and applying in tunnel waterproof layer and the major structure in the underpinning beam column frame to the upper structure of close-fitting; when the newly-built underground excavation engineering is closely attached to the upper structure bottom plate and penetrates through the existing structure pile foundation, the influence of underground excavation on the existing upper structure is reduced through temporary support of the full red support frame; meanwhile, the underpinning beam column is constructed, so that independent and complete stress systems of the existing structural pile foundation and the main structure of the underground excavated tunnel after the existing structural pile foundation is underpinned are guaranteed, the safety risk that the underground excavated pile foundation penetrates through the existing structural pile foundation under the existing structure is reduced, and the engineering safety of the whole process of underpinning construction of the underground excavated pile foundation is guaranteed.

Description

Underground excavation pile foundation underpinning system with closely-adhered lower penetrating existing structure

Technical Field

The utility model belongs to the technical field of the undercut tunnel engineering, concretely relates to undercut pile foundation underpins system.

Background

Along with the acceleration of the urbanization process of China, the demand quantity and the density of infrastructure increase, newly-built underground structure is more difficult to avoid and takes place the conflict with existing superstructure pile foundation, in order to guarantee the feasibility of newly-built engineering and the safety of existing structure, need to carry out the pile foundation underpinning to existing superstructure pile foundation. And the underground excavation tunnel engineering often accompanies the condition that the ground does not have the construction underpinning structure space, so the traditional mode that the pile foundation underpins and adopts the underpinning pile arranged on the ground to complete the pile foundation underpinning cannot be applied.

A referential method is provided for underpinning of a foundation of a subsurface excavated crossing pile, namely, underpinning of a pile foundation is completed by taking modes such as primary support or secondary lining of a subsurface excavated tunnel or additionally arranging a double-layer lining as an underpinning structure, but the underpinning modes are realized when the subsurface excavated construction is far away from an upper structure; when the upper structure is closely attached and the existing pile foundation is dug and penetrated, the method cannot be applied. Therefore, a method for underpinning the underground excavation pile foundation with a close-fitting and downward-penetrating existing structure is needed to be found, and the engineering safety of the whole process of underpinning the underground excavation pile foundation is ensured.

SUMMERY OF THE UTILITY MODEL

The utility model aims at providing a close-fitting is worn the undercut pile foundation underpinning system of existing structure down, when close-fitting superstructure undercut passes through existing pile foundation, in the face of the newly-built undercut engineering pile foundation underpinning condition of close-fitting existing bottom plate, can ensure undercut pile foundation underpins construction overall process engineering safety.

In order to achieve the above purpose, the utility model adopts the following technical scheme:

a close-fitting underground excavation pile foundation underpinning system penetrating an existing structure comprises a full red support for temporarily supporting a close-fitting upper structure, a lateral advanced support applied to an underground excavation tunnel, a primary support applied below a bottom plate of the existing structure, an underpinning beam column arranged in the primary support, a tunnel waterproof layer applied to a framework of the underpinning beam column and a main structure; when the newly-built excavation project is closely attached to the upper structure bottom plate and penetrates through the existing structure pile foundation, the influence of excavation on the existing upper structure is reduced through temporary support of the preset full red support; simultaneously through executing the underpinning beam column, both independent complete atress systems separately of existing structure pile foundation and undercut tunnel major structure after having guaranteed existing structure pile foundation underpins, can adopt the static to break the existing structure pile foundation that the mode chisel conflicts with undercut tunnel major structure with the help of this underpinning system, avoid the stable in structure problem that superstructure produced because of underground structure construction, the safe risk that the existing structure pile foundation was passed through in undercut under having reduced, ensure undercut pile foundation underpins construction overall process engineering safety.

The utility model discloses following beneficial effect has:

the utility model discloses wear the undercut pile foundation underpinning system of existing structure under the close-fitting, have when the close-fitting superstructure undercut passes through existing pile foundation, in the face of the newly-built undercut engineering pile foundation underpinning condition of the existing bottom plate of close-fitting, can ensure the undercut pile foundation underpins advantage of construction overall process engineering safety.

Drawings

FIG. 1 is a schematic elevation view of an underground excavation pile foundation underpinning system of the present invention, closely fitted with an underpinning existing structure;

FIG. 2 is a schematic plane view of the primary support grid steel frame and existing structural pile foundation connection of the present invention;

fig. 3 is a schematic plan view of the connection of the reinforcing bars of the underpinning beam and existing structural pile foundation of the present invention.

Detailed Description

The invention will be further described with reference to the accompanying drawings and specific embodiments so as to more clearly understand the technical idea claimed in the invention.

The underpinning system for the underground excavation pile foundation with the close-fitting and downward-penetrating existing structure as shown in the figures 1-3 is specifically carried out according to the following steps during construction: s1, presetting a full red support 16, constructing an undercut tunnel to the position in front of an existing structural pile foundation 15, presetting the full red support 16 to temporarily support a closely-adhered upper structure, and dismantling the full red support 16 after the construction of a main body structure of the undercut tunnel is completed and the designed strength is reached, wherein the full red support 16 supports and props up the full red support 16 from an existing structural bottom plate 11 to an existing structural middle plate 13, and the support range is that the plane of the existing structural pile foundation 15 to be underpinned extends for at least 5m outwards so as to ensure the support effect of the full red support 16;

s2, performing lateral advanced support on the underground excavated tunnel, wherein the underground excavated section is a rectangular section, performing advanced deep hole grouting 21 on the side wall and the bottom of the rectangular excavated section before underground excavation, arranging advanced small guide pipes 22 on the side wall of the upper step of the rectangular excavated section, and specifically, the advanced small guide pipes 22 have the diameter of 40mm, the row spacing of 300mm, the length of 2.5m and an external insertion angle of 15 degrees and are arranged at intervals of a grid steel frame 28 for primary support;

s3, constructing a primary support, excavating soil below the existing structural bottom plate 11 and constructing the primary support, wherein the underground excavation specifically adopts a step method for construction, the excavation footage is the same as the distance between grid steel frames 28 of the primary support, a temporary inverted arch 26 is arranged between the upper step and the lower step, the distance between the upper step and the lower step is 2.5m-3.5m, the primary support adopts a rectangular form, the side wall 23 of the primary support and the bottom 25 of the primary support are constructed along the excavation contour line, the top 24 of the primary support is supported on the bottom surface of the existing structural bottom plate 11 in a seamless manner, the grid steel frames 28 of the primary support are welded with the embedded bars 29 of the existing structural pile foundation 15, wherein the main bars of the grid steel frames 28 in the top 24 of the primary support, the bottom 25 of the primary support and the temporary inverted arch 26 are all welded with the embedded bars 29 of the existing structural pile foundation 15;

s4, setting a rectangular underpinning structure, arranging underpinning beam columns 31 in the primary support, and implanting underpinning top beams 32 and reinforcing steel bars 34 of bottom beams 33 of the underpinning beam columns 31 into the existing structural pile foundation 15;

and S5, chiseling the existing structure pile foundation 15 which conflicts with the main structure of the undercut tunnel in a static force removing mode, and constructing a tunnel waterproof layer 42 and a main structure 41 in the underpinning beam column frame.

In the primary support construction link, if the existing structural bottom plate 11 is not provided with the downward turning beam 12, the top 24 of the primary support is tightly attached to the bottom surface of the existing structural bottom plate 11; if the existing structural bottom plate 11 has the downward-turning beam 12, the primary support top 24 is tightly attached to the downward-turning beam 12, and the gap between the primary support top 24 and the existing structural bottom plate 11 is backfilled with C20 plain concrete 27, so that the primary support top 24 is always supported on the bottom surface of the existing structural bottom plate 11 in a seamless mode. When the existing structural pile foundation 15 is chiseled, attention should be paid to: excessive vibration is avoided when the existing structure pile foundation 15 is chiseled, and cracks of upper components and damage of reinforcing steel bars cannot be caused by chiseling the existing structure; the monitoring to superstructure should be strengthened to the chisel in-process of removing, and near existing structure pile foundation 15 chisel removing position adds vertical interim support in order to guarantee superstructure safety in the undercut tunnel if necessary.

When the newly-built excavation project is closely attached to the upper structure bottom plate and penetrates through the existing structure pile foundation 15, the influence of excavation on the existing upper structure is reduced through temporary support of the preset full red support 16; meanwhile, the underpinning beam column is constructed, so that the stress system which is independent and complete for the existing structural pile foundation 15 and the undercut tunnel main body structure after the existing structural pile foundation is underpinned is guaranteed, the problem of structural stability of the upper structure due to underground structure construction is solved, the safety risk that the undercut penetrates through the existing structural pile foundation 15 under the existing structure is reduced, and the engineering safety of the undercut pile foundation underpinning construction whole process is guaranteed.

Various other changes and modifications may be made by those skilled in the art based on the above-described technical solutions and concepts, and all such changes and modifications should fall within the scope of the present invention.

Claims (7)

1. The underpinning system for the underground excavated pile foundation with the closely-adhered upper structure penetrating downwards is characterized by comprising a full red support for temporarily supporting the closely-adhered upper structure, a lateral advanced support applied to an underground excavated tunnel, a primary support applied below a bottom plate of the existing structure, an underpinning beam column arranged in the primary support, and a tunnel waterproof layer and a main structure applied to the underpinning beam column frame.

2. The underpinning system for undercut pile foundation of claim 1, wherein said lateral advance supports are advanced deep hole grouting on the side walls and bottom of the rectangular excavation section and advanced small guide tubes on the side walls of the step on the rectangular excavation section before undercut excavation.

3. The close-fitting underpass existing structure undercut pile foundation underpinning system of claim 2, wherein said full rated red support props up from the existing structural floor support to the existing structural slab and extends at least 5m out of the plane of the existing structural pile foundation to be underpinned.

4. The closed under-run existing structure excavation pile foundation underpinning system of claim 2, wherein the primary supports are rectangular in form, the primary support side walls and the primary support bottom are applied along an excavation contour line, the primary support top is seamlessly supported on the bottom surface of the existing structure base plate, the primary support grid steel frames are welded to the embedded bars of the existing structure pile foundation, and the underpinning top beams of the underpinning beam columns and the steel bars of the underpinning bottom beams are embedded in the existing structure pile foundation.

5. A closed under-penetrating existing structure underground excavation pile foundation underpinning system according to claim 4, wherein the small lead pipe is 40mm in diameter, 300mm in row spacing, 2.5m in length, 15 ° in external insertion angle, and is laid every other primary-supported grid steel frame.

6. The system of claim 4, wherein the existing structural floor is free of downtilt beams and the primary support top is proximate the bottom surface of the existing structural floor.

7. The close-fitting under-run existing structure undercut pile foundation underpinning system of claim 4, wherein there is an under-turned beam on the existing structure floor, the top of the primary support is close-fitting to the under-turned beam, and the gap between the top of the primary support and the existing structure floor is backfilled with C20 plain concrete.

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