CN110344394A - A kind of surrounding deep foundation pit shallow embedding structure base ruggedized construction and construction method - Google Patents

Abstract

The invention discloses a foundation reinforcement structure and a construction method of a shallow buried structure around a deep foundation pit, comprising an anti-overturning plate, a grouted steel pipe, and a fixed steel plate. The anti-overturning plate is composed of a steel bar skeleton and concrete poured around the existing foundation , grouting steel pipes are arranged in a plum blossom shape around the existing foundation and are fixed by fixed steel plates and then connected with the steel skeleton of the anti-overturning plate. The construction steps are construction preparation → grouting hole drilling → grouting → foundation pit excavation → Reinforcement skeleton binding and fixed steel plate welding→concrete pouring and maintenance, the foundation is strengthened by laying grouted steel pipes around the existing foundation, and then the grouted steel pipes are fixed on the main reinforcement of the anti-overturning slab through the reinforcement steel plate, and finally the anti-overturning slab is poured Concrete forms a "pile cap", which can effectively solve the problems of long treatment time and inconspicuous reinforcement effect of the existing foundation, ensure the expansion of the bearing capacity and stability of the existing foundation, and at the same time have fast construction speed and good economic benefits Features.

Description

A foundation reinforcement structure and construction method for shallow buried structures around deep foundation pits

technical field

The invention belongs to the technical field of construction engineering foundation reinforcement construction, and in particular relates to a foundation reinforcement structure for shallow-buried structures around deep foundation pits, which is mainly used for foundation reinforcement of shallow-buried structures around deep foundation pits to ensure the safety of existing shallow-buried structures and at the same time The invention relates to a construction method for reinforcing the foundation of shallow buried structures around deep foundation pits.

Background technique

With the development of urbanization, the surrounding environment of the engineering construction site is becoming more and more complex. During the excavation of deep foundation pits, it is inevitable that the existing stratum will be disturbed, which will cause deformation of the foundation pit and displacement of the soil around the foundation pit. The safety of buildings is affected, especially the important structures around the foundation pit, which have extremely strict requirements on the stability of the foundation. If no measures are taken to reinforce it, once the deformation of the foundation pit exceeds the allowable range during the construction of the foundation pit, it will be very serious. It is easy to cause the structure to sink or overturn, causing extremely bad social impact and irreparable economic loss.

For structures around deep foundation pits, relocation or grouting reinforcement is generally adopted to reduce construction risks: when relocation is adopted, procedures such as approval layer by layer, demolition of existing structures, and construction of new structures are required, and the process is long and uncontrollable , the risk of delay in the construction period is greater; when the grouting reinforcement method is used, only the soil around the structure can be reinforced, and the soil below the foundation of the structure cannot be effectively reinforced, and the reinforcement effect is not obvious. Therefore, in order to reduce the safety risk of structures around deep foundation pits during the excavation process, it is particularly important to study and master feasible shallow-buried foundation reinforcement technologies for structures around deep foundation pits.

Contents of the invention

The first object of the present invention is to provide a foundation reinforcement structure for shallow buried structures around deep foundation pits with simple structure, convenient construction, little impact on existing shallow foundation structures, and good reinforcement effect.

The first object of the present invention is achieved through the following technical measures: a foundation reinforcement structure for shallow buried structures around deep foundation pits, including fixed steel plates, grouted steel pipes and anti-overturning plates arranged in sequence along the outer edge of the existing foundation , the anti-overturning plate includes a steel skeleton and concrete poured around the existing foundation. Holes are reserved in the position, the grouted steel pipes are arranged circumferentially along the existing foundation, and the number of layouts is not less than 2 rings. The holes reserved in the steel plate are welded and fixed together with the fixed steel plate.

As an improvement, the steel frame is a double-layer steel mesh, and the steel frame is connected to the existing foundation by planting bars.

As an improvement, the front end of the grouting steel pipe is provided with a cone head, the tail end is provided with a grout stop section, and the middle part is provided with grout overflow holes arranged at equidistant intervals.

As an improvement, the thickness of the cone head is not less than 10cm, the length of the slurry stop section is not less than 1.5m, the distance between the overflow holes is 15cm, and the overflow holes are arranged in a quincunx shape with a diameter of 10-16mm .

As an improvement, the fixed steel plate connects the grouted steel pipes into a whole, and is welded and fixed firmly with the steel skeleton. The fixed steel plate includes a first fixed steel plate and a second fixed steel plate. The first fixed steel plate, the second fixed steel plate Layer-fixed steel plates are respectively located above and below the reinforcement skeleton.

As an improvement, the fixed steel plate is made of a 1 cm steel plate, and the width of the fixed steel plate is three times the diameter of the grouted steel pipe.

As an improvement, two fixed steel plates are arranged outwards along the existing foundation.

As an improvement, its construction method is characterized by the following steps:

Step 1: Construction preparation

Organize on-site investigations, conduct an all-round survey of the surrounding pipelines of the existing foundation to be reinforced, find out the location of underground pipelines; carry out site leveling and preparation of manpower, machinery and materials.

Step 2: Drilling the grouting hole

The scope of foundation reinforcement is 3 to 5 times the width of the existing foundation. The grouting holes are arranged in double rows along the perimeter of the existing foundation in a plum blossom shape, with a hole spacing of 1.3m×1.3m, and the distance between the inner row of grouting holes and the outer side of the existing foundation is not less than 1m; The diameter of the grouting hole is 5-10mm larger than the diameter of the grouting steel pipe, and the hole depth is double-controlled by 10m and entering the rock formation not less than 2m. The top elevation of the grouting steel pipe is the same as that of the existing foundation top surface of the reinforced structure. The vertical and horizontal error shall not exceed ±50mm, the allowable error of verticality shall not exceed 3‰, and the thickness of the sediment after cleaning the hole shall not exceed 50mm.

Step 3: Grouting

Grouting steel pipe 1 uses M30 cement slurry for grouting, the water-cement ratio is generally 0.5-1 (determined according to the grouting test), and an appropriate amount of retarder is added. The cement is P.O.42.5 ordinary Portland cement, and the mixing water is drinking water. Water; the grouting pump is used for grouting, and the hole is sealed with thick grout at the end of grouting, and the grouting pressure is controlled at about 0.2-0.5MPa.

Step 4: Excavation of foundation pit

Use an excavator to excavate the earth around the existing foundation of the structure that needs to be reinforced. The excavation slope is 1:1.5, and the excavation depth is 0.5-1.0m. Manual excavation is adopted within the scope, and attention should be paid to strengthening the protection of the grouted steel pipe during excavation to avoid breaking and damage to the grouted steel pipe.

Step 5: Binding of reinforcement skeleton and welding of fixed steel plate

Lightly hammer and chisel the surface of the existing foundation of the structure, and clean up the loose particles and scum and dust on the surface of the existing foundation, and set reinforcement holes on the existing foundation according to the position of the steel skeleton; fix the first layer The steel plate is penetrated into the grouted steel pipe and welded and fixed, and the steel frame binding is started. After the steel frame binding is completed, the second layer of fixed steel plate is penetrated, and the contact part of the fixed steel plate and the steel frame is connected by double-sided full welding.

Step 6: Concrete pouring and maintenance

Install the formwork according to the size of the anti-overturning slab and apply an interface agent on the existing foundation at the contact position of the anti-overturning slab for treatment, and then pour the anti-overturning slab concrete; after the concrete is poured, it should be covered and cured within 12 hours under normal temperature conditions. The frequency of watering is appropriate to keep the concrete moist, and the curing time is not less than seven days and nights.

Compared with prior art, the present invention has following advantage:

(1) The existing foundation is reinforced by grouting steel pipes. At the same time, the grouting steel pipes and the anti-overturning plate form a "pile cap" as a whole, which effectively increases the bearing capacity and stability of the existing foundation, and the reinforcement effect is good.

(2) The construction process of the present invention is relatively simple, which can avoid related problems caused by the relocation and modification of existing structures, and has high construction speed and high efficiency.

(3) The present invention reinforces the foundation of the structures around the foundation pit in situ, and requires less resources such as machinery and materials. Compared with the relocation of structures, it does not need to be demolished and newly built, the construction cost is significantly reduced, and the economic benefits are good.

Description of drawings

Fig. 1 is a schematic diagram of a grouted steel pipe for the foundation reinforcement structure and construction method of a shallow buried structure around a deep foundation pit according to the present invention.

Fig. 2 is a schematic plan layout diagram of a grouted steel pipe for the foundation reinforcement structure and construction method of a shallow buried structure around a deep foundation pit according to the present invention.

Fig. 3 is a schematic diagram of a excavation section of a foundation pit excavation of a shallow buried structure foundation reinforcement structure and construction method around a deep foundation pit according to the present invention.

Fig. 4 is a schematic diagram of the connection plane between the steel skeleton and the fixed steel plate of a foundation reinforcement structure and construction method of a shallow buried structure around a deep foundation pit according to the present invention.

Fig. 5 is a schematic cross-sectional view of the connection between the steel skeleton and the fixed steel plate of a foundation reinforcement structure and construction method of a shallow buried structure around a deep foundation pit according to the present invention.

Fig. 6 is a schematic cross-sectional view of a reinforcement structure and a construction method for a shallow buried structure around a deep foundation pit according to the present invention.

Reference signs: 1, grouting steel pipe, 101, cone head, 102, slurry stop section, 103, overflow hole, 2, fixed steel plate, 201, first layer of fixed steel plate, 202, second layer of fixed steel plate, 3, Anti-overturning board, 301, foundation pit excavation line, 302, steel skeleton, 4, existing foundation.

Detailed ways

In order to better understand the technical solution of the present invention, the present invention will be further described in detail below in conjunction with the accompanying drawings of the embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

A foundation reinforcement structure for shallow buried structures around deep foundation pits, characterized in that it includes fixed steel plates 2, grouted steel pipes 1, and anti-overturning plates 3 arranged in sequence along the outer edge of the existing foundation 4, and the anti-overturning plates 3 Including the steel skeleton 302 and the concrete poured around the existing foundation 4, the fixed steel plate 2 is arranged outside the existing foundation 4 in a square shape and is located in the poured concrete, and the fixed steel plate 2 is arranged according to the arrangement of the grouted steel pipe 1. Holes are reserved in the position, the grouting steel pipes (1) are arranged circumferentially along the existing foundation (4), and the number of layouts is not less than 2 rings. The tail end of the ring grouting steel pipe (1) passes through the reserved hole of the fixed steel plate (2) and is welded and fixed together with the fixed steel plate (2).

As a preferred implementation manner of this embodiment, the reinforcement frame 302 is a double-layer reinforcement mesh, and the reinforcement frame 302 is connected to the existing foundation 4 by planting bars.

As a preferred implementation of this embodiment, the grouting steel pipe 1 is provided with a conical head 101 at the front end, a grout stop section 102 at the rear end, and grout overflow holes 103 arranged at equal intervals in the middle part.

As a preferred implementation mode of this embodiment, the degree of the cone head 101 is not less than 10cm, the length of the slurry stop section 102 is not less than 1.5m, the distance between the slurry overflow holes 103 is 15cm, and the slurry overflow The holes 103 are arranged in a quincunx shape with a diameter of 10-16 mm.

As a preferred implementation of this embodiment, the fixed steel plate 2 connects the grouted steel pipe 1 as a whole, and is welded and fixed firmly with the reinforcement frame 302. The fixed steel plate 2 includes a first layer of fixed steel plate 201, a second layer of The fixed steel plates 202, the first layer of fixed steel plates 201 and the second layer of fixed steel plates 202 are respectively located above and below the reinforcement frame 302.

As a preferred implementation of this embodiment, the fixed steel plate 2 is made of a 1 cm steel plate, and the width of the fixed steel plate 2 is about three times the diameter of the grouted steel pipe 1 .

A construction method for reinforcing the foundation of a shallow buried structure around a deep foundation pit, characterized by comprising the following steps:

Step 1: Construction preparation

Organize on-site investigations, conduct an all-round survey of the surrounding pipelines of the existing foundation 4 to be reinforced, find out the location of underground pipelines; carry out site leveling and preparation of manpower, machinery and materials.

Step 2: Drilling the grouting hole

The scope of foundation reinforcement is 3 to 5 times the width of the existing foundation 4. The grouting holes are arranged in double rows along the perimeter of the existing foundation 4 in a quincunx shape. The distance between the holes is 1.3m×1.3m. Less than 1m; the diameter of the grouting hole is 5-10mm larger than the diameter of the grouting steel pipe 1, and the hole depth is double-controlled according to 10m and the entry rock formation is not less than 2m. The elevation of the top of the grouting steel pipe 1 is the same as that of the existing foundation 4 of the reinforced structure , The vertical and horizontal error of the grouting hole position shall not exceed ±50mm, the allowable error of the verticality shall not exceed 3‰, and the thickness of the sediment after cleaning the hole shall not exceed 50mm.

Step 3: Grouting

Grouting steel pipe 1 uses M30 cement slurry for grouting, the water-cement ratio is generally 0.5-1 (determined according to the grouting test), and an appropriate amount of retarder is added. The cement is P.O.42.5 ordinary Portland cement, and the mixing water is drinking water. Water; the grouting pump is used for grouting, and the hole is sealed with thick grout at the end of grouting, and the grouting pressure is controlled at about 0.2-0.5MPa.

Step 4: Excavation of foundation pit

Use an excavator to excavate the earth around the existing foundation 4 of the structure to be reinforced. The excavation slope is 1:1.5, and the excavation depth is 0.5-1.0m. Manual excavation is adopted within a range of 50 cm. During excavation, attention should be paid to strengthening the protection of the grouted steel pipe 1 to avoid breaking and damage to the grouted steel pipe 1.

Step 5: Binding of reinforcement frame 302 and welding of fixed steel plate 2

Lightly hammer and chisel the surface of the existing foundation 4 of the structure, and clean up the loose particles and scum and dust on the surface of the existing foundation 4, and set reinforcement holes on the existing foundation 4 according to the position of the steel skeleton 1; The first layer of fixed steel plate 201 is penetrated into the grouted steel pipe and welded and fixed, and the reinforcement frame 302 is bound. Full face solder connection.

Step 6: Concrete pouring and maintenance

Install the formwork according to the size of the anti-overturning slab 3 and apply an interface agent on the contact position of the existing foundation 4 to the anti-overturning slab 3 for treatment, and then pour the concrete for the anti-overturning slab 3; after the concrete is poured, it should be covered and poured within 12 hours under normal temperature conditions For water curing, the frequency of watering should be to keep the concrete moist, and the curing time should not be less than seven days and nights.

The above-mentioned embodiments of the present invention are only examples for clearly illustrating the present invention, rather than limiting the implementation of the present invention. For those of ordinary skill in the art, on the basis of the above description, other Variations or changes in different forms cannot be exhaustively listed here, and any obvious changes or changes derived from the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims (7)

1. a kind of surrounding deep foundation pit shallow embedding structure base ruggedized construction, it is characterised in that: including along existing basic (4) outer to Fixation steel plate (2), slip casting steel pipe (1) and the antidumping plate (3) set gradually outside, the antidumping plate (3) includes reinforcing bar It frame (302) and pours in the concrete of existing basic (4) surrounding, the fixation steel plate (2), which is square, is set to existing basic (4) Outside is simultaneously located in the concrete poured, and the fixation steel plate (2) is equipped with according to slip casting steel pipe (1) position preformed hole Hole, the slip casting steel pipe (1) is circumferentially disposed along existing basic (4) surrounding, and arrangement quantity is no less than 2 rings, adjacent 2 ring slip casting steel pipe It (1) is in quincunx interlaced arrangement, same ring slip casting steel pipe (1) tail end passes through fixation steel plate (2) reserving hole and fixation steel plate (2) It is welded and fixed together.

2. a kind of surrounding deep foundation pit shallow embedding structure base ruggedized construction according to claim 1, it is characterised in that: described Framework of steel reinforcement (302) is double layer bar, and the framework of steel reinforcement (302) is connected by the way of bar planting with existing basic (4) It connects.

3. a kind of surrounding deep foundation pit shallow embedding structure base ruggedized construction according to claim 1, it is characterised in that: described The conehead (101) that slip casting steel pipe (1) front end is equipped with, tail end are equipped with only slurry section (102), and middle section is equipped with equidistant interval setting Extravasating hole (103).

4. a kind of surrounding deep foundation pit shallow embedding structure base ruggedized construction according to claim 3, it is characterised in that: described The degree of conehead (101) is not less than 10cm, and the length of only slurry section (102) is not less than 1.5m, the spacing of the extravasating hole (103) For 15cm, the extravasating hole (103) is 10~16mm in quincuncial arrangement and aperture.

5. a kind of surrounding deep foundation pit shallow embedding structure base ruggedized construction according to claim 1, it is characterised in that: described Fixation steel plate (2) is integral by slip casting steel pipe (1) connection, and is welded and fixed securely with framework of steel reinforcement (302), the fixed steel Plate (2) includes first layer fixation steel plate (201), second layer fixation steel plate (202), the first layer fixation steel plate (201), second Layer fixation steel plate (202) is located at the over and under of framework of steel reinforcement (302).

6. a kind of surrounding deep foundation pit shallow embedding structure base ruggedized construction according to claim 5, it is characterised in that: described Fixation steel plate (2) is made by 1cm steel plate, and fixation steel plate (2) width is 3 times of 1 diameter of slip casting steel pipe.

7. a kind of construction method of above-mentioned surrounding deep foundation pit shallow embedding structure base ruggedized construction, feature comprise the steps of:

Step 1: preparation of construction

Field investigation is organized, basic (4) periphery line conditions progress existing to quasi- reinforcing is comprehensive to sound out the people in a given scope one by one in order to break a criminal case, and verifies underground utilities position It sets；Carry out levelling of the land and people, machine, material preparation.

Step 2: injected hole is drilled with

Strengthening of foundation range is 3~5 times of existing basic (4) width, and injected hole is along the double quincunx cloth of existing basic (4) surrounding It sets, pitch-row 1.3m × 1.3m, interior row's injected hole is not less than 1m away from spacing on the outside of existing basic (4)；Slip casting bore dia is than slip casting steel Manage the big 5~10mm of (1) diameter, hole depth according to 10m and enter rock stratum be not less than 2m dual control, slip casting steel pipe (1) top mark height with it is added Solid existing basic (4) top surface absolute altitude of structures it is identical, error must not exceed ± 50mm to injected hole hole location in length and breadth, and verticality allows Error is not to be exceeded 3 ‰, and sediment thickness is not more than 50mm after borehole cleaning.

Step 3: mud jacking

(1) slip casting of slip casting steel pipe uses M30 cement grout, and the ratio of mud is generally 0.5~1 (being determined by grouting test), and Appropriate retarder is mixed, cement uses P.O.42.5 ordinary portland cement, and mixing water uses drinking water；It is carried out using mudjack Mud jacking uses underflow sealing of hole at the end of mud jacking, and controlled grouting pressure is in 0.2~0.5MPa or so.

Step 4: excavation of foundation pit

It is excavated using excavator basic (4) periphery cubic metre of earth existing to the structures that need to be reinforced, excavates gradient 1:1.5, excavate 0.5~1.0m of depth, nearby the 10cm soil body is used within the scope of the 50cm of basis excavation of foundation pit line (301) using artificial clear bottom Hand excavation, when excavation, should be noted the protection reinforced to slip casting steel pipe 1, avoid slip casting steel pipe 1 and fracture, is damaged.

Step 5: framework of steel reinforcement (302) binding and fixation steel plate (2) welding

It is existing to structures basis (4) surface chisel face gently hammer, dabbing, and clean out it is existing basis (4) surface discrete particles And dross dust, bar planting hole is set on existing basic (4) according to the position of framework of steel reinforcement (1)；By first layer fixation steel plate (201) it penetrates slip casting steel pipe and is welded and fixed, start framework of steel reinforcement (302) binding, penetrated after the completion of framework of steel reinforcement (302) binding Fixation steel plate (2) will and be carried out two-sided be fully welded with framework of steel reinforcement (302) contact site and connect by second layer fixation steel plate (202).

Step 6: concreting and maintenance

Template installation is carried out and in existing basic (4) in antidumping plate (3) contact position brushing circle according to antidumping plate (3) size Face agent is handled, and antidumping plate (3) concreting is then carried out；After concreting, it should be covered in 12h under normal temperature conditions Lid water seasoning, for irrigation times to keep concrete is wet to be advisable, curing time is no less than sennight.