A combined structure of deep foundation pit retaining piles and curtain waterstop

Abstract

This invention relates to a combined structure of deep foundation pit retaining piles and curtain wall waterproofing, comprising a steel mesh installed on the side of the earthen cofferdam, an internally drilled pile installed below the outer side of the steel mesh, a capping beam installed at the upper end of the internally drilled pile, a waist beam fixedly connected to the outer side of the internally drilled pile, the waist beam having a downward slope, a support seat installed below the outer side of the waist beam, the support seat having an upward slope, a diagonal bracing column fixed between the downward slope of the waist beam and the upward slope of the support seat, a reinforcing seat cast on the diagonal bracing column, and a drainage ditch installed below the reinforcing seat. The structure has strong stability, is not difficult to construct, has an extended service life, and is suitable for long-term use conditions.

Description

Technical Field

[0001] This invention belongs to the field of building construction technology, specifically relating to a combined structure of deep foundation pit retaining piles and curtain waterstop. Background Technology

[0002] In the field of road construction, the construction of roads with water on adjacent sides requires the use of support structures. The existing support structures used are cast-in-place piles and inclined bracing. However, the inclined bracing structure uses soil nailing walls. Based on this, the inclined bracing is directly placed between the inner and outer cast-in-place piles. Although this structure can be used, its service life is not long and it is not suitable for long-term working conditions. Summary of the Invention

[0003] The purpose of this invention is to provide a combined structure of deep foundation pit retaining piles and curtain waterstop, which has strong structural stability, low construction difficulty, extended service life, and is suitable for working conditions with long service life.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a combined structure of deep foundation pit retaining piles and curtain water-stop, including a steel mesh set on the side of the earthen cofferdam, an inner bored pile set below the outer side of the steel mesh, a capping beam set at the upper end of the inner bored pile, a waist beam fixedly connected to the outer side of the inner bored pile, the waist beam having a downward slope, a support seat set below the outer side of the waist beam, the support seat having an upward slope, a diagonal bracing column fixed between the downward slope of the waist beam and the upward slope of the support seat, a reinforcing seat cast on the diagonal bracing column, and a drainage ditch set below the reinforcing seat.

[0005] Furthermore, a three-axis mixing pile is installed in the earthen cofferdam, and a fixed anchor pipe is installed between the steel mesh and the earthen cofferdam.

[0006] Furthermore, the upper end of the crown beam is fastened to the lower outer side of the steel mesh.

[0007] Furthermore, the waist beam and the internally drilled pile are an integral structure.

[0008] Furthermore, the crown beam and the internally drilled pile are an integral structure; an externally drilled pile is installed below the support base, and the support base and the externally drilled pile are an integral structure.

[0009] Furthermore, the outer side of the steel mesh is a sloping surface that is higher on the inside and lower on the outside, with an angle of (3-5)°.

[0010] Furthermore, a drainage reinforcement section is provided between the outer end of the outer side of the steel mesh and the upper end of the waist beam, and the inner wall of the drainage reinforcement section is fastened to the outer side of the crown beam and the outer side of the waist beam.

[0011] Furthermore, the angle of the diagonal bracing column is (35-40)°; and the reinforcing seat is filled with an internal support component.

[0012] A construction process for a deep foundation pit retaining pile and curtain water-stop combined structure includes the following steps: trench excavation → simultaneous breaking of pile heads of internal and external bored piles → adjustment of pile head reinforcement → binding of cap beam reinforcement → assembly of cap beam formwork → concrete pouring → curing → formwork removal.

[0013] Furthermore, once the concrete strength of the pile body reaches 70% or more, the construction of the capping beam, waist beam, diagonal bracing columns, internal support components, and support base can begin.

[0014] The present invention has the following technical effects: Based on the traditional support pile and inclined bracing type support, the present invention adopts a method of setting a waist beam and a support seat at both ends of the inclined bracing column support, and setting a support slope on the waist beam and the support seat to ensure the required support angle of the inclined bracing column. Based on this, a reinforcing seat is poured and drainage is used for drainage. The structure is highly stable, the construction difficulty is not high, and the service life can reach more than 10 years, which can be applied to working conditions with long service life. Attached Figure Description

[0015] Figure 1 This is a structural diagram of the present invention;

[0016] Figure 2 This is a flowchart illustrating the construction process of rotary drilling cast-in-place piles (including internally drilled piles 2) according to the present invention. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] A combined structure of deep foundation pit retaining piles and curtain water-stop includes a steel mesh 1 set on the side of the earthen cofferdam a, an internally drilled pile 2 set below the outer side of the steel mesh 1, a cap beam 3 set at the upper end of the internally drilled pile 2, a waist beam 4 fixedly connected to the outer side of the internally drilled pile 2, the waist beam 4 having a downward slope, a support seat 6 set below the outer side of the waist beam 4, the support seat 6 having an upward slope, a diagonal bracing column 7 fixed between the downward slope of the waist beam 4 and the upward slope of the support seat 6, a reinforcing seat 8 cast on the diagonal bracing column 7, and a drainage ditch 9 set below the reinforcing seat 8.

[0019] Based on traditional cast-in-place pile and inclined bracing support, this invention uses inclined bracing columns 7 to support the two ends of the bearings, with waist beams 4 and support seats 6 respectively. The waist beams 4 and support seats 6 are respectively provided with support slopes to ensure the required support angle of the inclined bracing columns 7. Based on this, a reinforcing seat 8 is poured and drainage is carried out using drainage channels 9. The structure is highly stable, the construction difficulty is not high, and the service life can reach more than 1 year, making it suitable for working conditions with long service life.

[0020] Furthermore, a triaxial mixing pile 5 is installed in the earthen cofferdam a, and a fixed anchor pipe is installed between the steel mesh 1 and the earthen cofferdam a.

[0021] Furthermore, the upper end of the crown beam 3 is fastened to the lower side of the outer side of the steel mesh 1.

[0022] This is the specific layout structure of steel mesh 1.

[0023] Furthermore, the waist beam 4 and the internally drilled pile 2 are integrally constructed.

[0024] Furthermore, the crown beam 3 and the inner bored pile 2 are integrally constructed; an outer bored pile 61 is provided below the support base 6, and the support base 6 and the outer bored pile 61 are integrally constructed.

[0025] In practice, the preferred method is to use an integrated steel reinforcement structure where the protruding reinforcing bars on the side of the internally drilled pile 2 are integrated with the wainscoting 4, and the protruding reinforcing bars on the top of the internally drilled pile 2 are integrated with the capping beam 3, and then cast to form the internally drilled pile 2, wainscoting 4, and capping beam 3. Similarly, the protruding reinforcing bars on the top of the externally drilled pile 61 are integrated with the support base 6, and then cast to form the externally drilled pile 61 and support base 6.

[0026] Furthermore, the outer side of the steel mesh 1 is a sloping surface with a higher inner surface and a lower outer surface, and the angle of the sloping surface is (3-5)°.

[0027] In this way, the material debris from the construction of the steel mesh 1 can be conveniently and smoothly discharged at this angle, which also facilitates the subsequent drainage of rainwater.

[0028] Furthermore, a drainage reinforcement part 10 is provided between the outer end of the outer side of the steel mesh 1 and the upper end of the waist beam 4. The inner wall of the drainage reinforcement part 10 is fastened to the outer side of the crown beam 3 and the outer side of the waist beam 4.

[0029] The drainage reinforcement section 10 reinforces the upper end of the weaker inclined support column 7, thus strengthening the entire upper part, including the waist beam 4. The upward component of the supporting force on the upper end of the inclined support column 7 is borne by the drainage reinforcement section 10. Based on this, the drainage reinforcement section 10 has a wedge-shaped structure, facilitating the removal of debris and rainwater from the steel mesh 1. Meanwhile, the lower end of the inclined support column 7, with its downward supporting force, is directly supported by the externally drilled pile 61 below the support base 6, resulting in a stable and robust structure.

[0030] Furthermore, the angle of the inclined support column 7 is (35-40)°; the reinforcing seat 8 is filled with an internal support member.

[0031] This is the preferred arrangement of the diagonal bracing column 7.

[0032] The retaining piles of the present invention include a cap beam 4, a bracing platform (i.e., a bracing column 7 and a support seat 6), a waist beam 4, and an inner support member (the support member in the reinforcing seat 8).

[0033] Furthermore, the steel mesh 1 is a C20 shotcrete reinforced steel mesh.

[0034] The foundation soil of the proposed construction site is composed of the following layers from top to bottom: ① miscellaneous fill, ② clay, ③ (strongly) weathered argillaceous sandstone. (Refer to...) Figure 1 , Figure 1 The left side shows, from top to bottom, layers of miscellaneous fill, clay, and weathered argillaceous sandstone.

[0035] The proposed site is located within the Jianghuai undulating plain geomorphological unit, with the micro-topography being hilly terrain. The lithology and distribution patterns of each soil and rock layer are described below:

[0036] ① Layer of miscellaneous fill: Layer thickness 0.50–6.30m, bottom elevation 27.77–35.19m. Variegated color, wet, loose state. Rich in construction waste, filled with cohesive soil, locally interspersed with silty soil, surface layer rich in plant roots and stems, etc.

[0037] ② Clay layer: Due to the limitation of borehole depth, some exploration boreholes did not penetrate this layer, with the maximum exposed layer thickness being 16.000m. It is grayish-brown, yellowish-brown, brownish-yellow, and brown, slightly moist, in a hard plastic state, with a smooth and glossy cut surface, containing a small amount of iron and manganese nodules, showing no shaking reaction, and exhibiting high dry strength and high toughness.

[0038] ③ Layer of heavily weathered argillaceous sandstone: This layer was not penetrated, with a maximum exposed thickness of 4.70m. It is brownish-red, moist, and dense. The rock mass is severely damaged, weathered into a sandy loam state, with localized blocky inclusions. It can be drilled with a dry drill and contains feldspar and a small amount of mica. The rock mass is characterized by its fractured state, and its basic quality grade is V.

[0039] The retaining structure of the foundation pit of this invention utilizes bored cast-in-place piles (i.e., internal bored piles 2 and external bored piles 61) for partial support. The drilling rig is operated by a fully hydraulic system, ensuring that all indicators, including pile verticality, hole position, hole depth, and sediment thickness, meet the requirements of the construction specifications. The drilling rig is suitable for various geological conditions, has high drilling efficiency, good hole wall stability, thorough hole cleaning after drilling, and fast construction progress. Construction noise is low, and it does not pollute the environment.

[0040] The foundation pit structure of this invention is internally supported by internal supports and inclined bracing columns 7, specifically constructed using steel supports (inclined bracing columns 7) consisting of a waist beam 4 and support base 6. Each support base 6 (forming a support pile cap) is equipped with two externally drilled piles 61 (cap piles). The two externally drilled piles 61 use the same assembly process as the retaining piles, both being rotary-drilled cast-in-place piles. During the construction of the externally drilled piles 61, the borehole opening is promptly protected or covered with backfill after concrete pouring.

[0041] The above-mentioned rotary drilling and grouting pile construction process is referred to Figure 2 To ensure the construction quality of rotary drilling cast-in-place piles.

[0042] The aforementioned crown beam 3, diagonal bracing platform (i.e., diagonal bracing column 7 and support seat 6), waist beam 4, and internal support components (support components in reinforcing seat 8):

[0043] The supporting pile formed by the structure of this invention has a cast-in-place capping beam 3 at its top, and the main reinforcing bars of the capping beam 3 are connected by welding or mechanical connection. C30 concrete is used. The capping beam 3 and the internally drilled pile 2 are integrally reinforced.

[0044] Construction process of this invention: trench excavation → simultaneous breaking of pile heads of internal drilled pile 2 and external drilled pile 61 → adjustment of pile head reinforcement → binding of reinforcement of capping beam 3 → assembly of capping beam 3 formwork → concrete pouring → curing → formwork removal.

[0045] Preferably, construction of the cap beam 3, waist beam 4, diagonal bracing column 7, internal support components and support seat 6 begins when the concrete strength of the pile body reaches 70% or more.

[0046] When breaking the pile head, avoid damaging the main reinforcement bars. Remove and clean the loose concrete, and moisten the concrete joint with water. Expose at least 600mm of the main reinforcement bars from the pile head, and roughen the area within 100mm of the pile head. Tie the No. 3 reinforcement bars of the capping beam. After the tying is completed and deemed satisfactory, proceed to the next step.

[0047] When installing reinforcing bars inside the formwork of the cap beam 3, in order to ensure the thickness of the protective layer between the formwork and the reinforcing bars, spacers are placed under the reinforcing bars and fixed to the reinforcing bars with wire or other fasteners to prevent the spacers from moving during concrete pouring.

[0048] Preferably, the formwork for the capping beam 3 uses 15mm thick wooden formwork with 50×100mm timber backing. The joints of the capping beam 3 formwork are firm and do not deform. Concrete pouring for the capping beam 3 is carried out using a combination of mechanical and manual methods. Concrete is poured horizontally in layers from bottom to top, with the upper layer poured before the lower layer has initially set; concrete pouring is continuous. Concrete vibration is performed at the pouring point and on the surface of the newly poured concrete. An immersion vibrator is used, inserted vertically into the concrete, penetrating 10cm into the previous layer, with quick insertion and slow withdrawal to ensure good bonding between the newly poured and previously poured concrete. During insertion, avoid collisions between the vibrator and the formwork, reinforcing bars, and embedded parts. The vibrator's movement interval is 1-1.5 times the effective vibration radius.

[0049] Preferably, the construction of the diagonal bracing column 7 includes the following steps:

[0050] 1) Excavate the bored piles 2 and the capping beam 3 inside the construction retaining piles, and excavate to the elevation of the waist beam 4 and construct the waist beam 4;

[0051] 2) Reserve earthwork for construction of external bored piles 61 and support bases 6;

[0052] 3) Install diagonal bracing columns 7, excavate the earthwork, install water-stop steel plates and drainage channels 9, and construct the main structure;

[0053] 4) Construction diversion and reinforcement section 10.

[0054] Furthermore, the upper and lower ends of the diagonal brace 7 are slotted at the connection points between the waist beam 4 and the support seat 6, and the slots are provided for the diagonal brace 7 to be stably arranged.

[0055] In addition, the cold joints generated during the construction of the water-stop curtain of the triaxial mixing pile 5 on the inner side of the steel mesh 1 shall be treated in the following way:

[0056] 1) When the time interval between the joint piles exceeds 24 hours but does not exceed 48 hours: directly drive the subsequent three-axis curtain wall and drive one three-axis mixing pile on the outside;

[0057] 2) The time interval between the joints and piles exceeds 48 hours: The cold joint between the piles constructed successively is sealed by double-pipe jet grouting piles with a cement content of 30%, a water-cement ratio of 1:1, and a depth the same as that of the three-axis curtain wall.

[0058] Any calculation scheme that is the same as or similar to that of this invention without departing from the principles of this invention falls within the protection scope of this invention.

Claims

1. A combined structure of retaining piles and curtain wall for deep foundation pits, characterized in that, The structure includes a steel mesh (1) located outside the earthen cofferdam (a), an inner bored pile (2) located below the outer side of the steel mesh (1), a cap beam (3) located at the upper end of the inner bored pile (2), a waist beam (4) fixedly connected to the outer side of the inner bored pile (2), the waist beam (4) having a downward slope, a support seat (6) located below the outer side of the waist beam (4), the support seat (6) having an upward slope, a diagonal bracing column (7) fixed between the downward slope of the waist beam (4) and the upward slope of the support seat (6), a reinforcing seat (8) cast on the diagonal bracing column (7), and a drainage ditch (9) located below the reinforcing seat (8); a triaxial mixing pile (5) is installed in the earthen cofferdam (a), and the steel mesh (1) and the earthen cofferdam (a) are connected... Fixed anchor pipes are set in the middle; the upper end of the crown beam (3) is fastened to the lower side of the outer side of the steel mesh (1); the crown beam (3) and the inner bored pile (2) are integral structures; an outer bored pile (61) is set below the support seat (6), and the support seat (6) and the outer bored pile (61) are integral structures; the outer side of the steel mesh (1) is a slope with the inner side higher than the outer side; a drainage reinforcement part (10) is set between the outer end of the outer side of the steel mesh (1) and the upper end of the waist beam (4), and the inner wall of the drainage reinforcement part (10) is fastened to the outer side of the crown beam (3) and the outer side of the waist beam (4); an inner support is cast in the reinforcing seat (8); the waist beam (4) and the inner bored pile (2) are integral structures.

2. The combined structure of deep foundation pit retaining piles and curtain waterstop as described in claim 1, characterized in that, The construction process includes the following steps: trench excavation → simultaneous breaking of the pile heads of internal drilled piles (2) and external drilled piles (61) → adjustment of pile head reinforcement → binding of reinforcement of capping beam (3) → assembly of capping beam (3) formwork → concrete pouring → curing → formwork removal.

3. The combined structure of deep foundation pit retaining piles and curtain waterstop as described in claim 2, characterized in that, When the concrete strength of the pile body reaches more than 70%, the construction of the cap beam (3), waist beam (4), diagonal bracing column (7), internal support components and support seat (6) can begin.

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