Strip-shaped concrete foundation reinforced by newly-added reinforced concrete and construction method

Abstract

The invention relates to a concrete strip-shaped foundation reinforced in a newly-added reinforced concrete mode and a construction method, newly-added concrete is located on the two sides of an original strip-shaped foundation, when the foundation bears eccentric pressure, an asymmetric widened strip-shaped foundation is adopted, and when the foundation bears center pressure, a symmetric widened strip-shaped foundation is adopted; after the ring main reinforcement is bent, the lower end of the newly-added concrete is connected with the original strip-shaped foundation main reinforcement, and the upper end of the newly-added concrete is anchored into the ground beam II; the horizontal steel bars in the newly added concrete are welded with the ring main bars, and the horizontal steel bars and the stirrups are bound; the ring main reinforcements of the newly added concrete and the anchoring reinforcements are welded together; one anchoring steel bar is implanted every 300-400 mm in the direction of the second ground beam, one anchoring steel bar is implanted every 400 mm in the horizontal direction, and the newly-added concrete is divided into independent sections every 1500-2000 mm in the horizontal direction. The method has the most remarkable advantage that the strength, rigidity and durability of the foundation can be effectively improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of urban renewal and reinforcement of existing building structures, and particularly relates to a method for reinforcing a concrete strip foundation by adding new reinforced concrete, which is suitable for concrete strip foundation projects that need to be reinforced due to increased load, decreased foundation bearing capacity, or insufficient seismic performance. BACKGROUND

[0002] With the increasing number of existing buildings, structural reinforcement may be a very popular industry in the future. The purpose of structural reinforcement is to improve bearing capacity, improve seismic performance, repair damage (cracks, corrosion, etc.), change use function (increase load), and prolong service life, etc.

[0003] Strip foundations are widely used in low-rise or multi-story buildings, but when the building load increases (such as adding stories or renovation) or the foundation soil bearing capacity decreases, the original foundation may not meet the requirements. The traditional widening method (such as grouting and piling, steel plate reinforcement) has problems such as complex construction, poor stress coordination between new and old foundations, etc.

[0004] In existing reinforcement technologies, the reinforcement method for concrete strip foundations (such as the "reinforcement of concrete strip foundations by adding an external concrete sleeve" described in patent document CN114991557A) has the following technical problems:

[0005] Dependence on anchor angle steel and wall penetrating bolts for connection and fixation, long-term stress can cause the bolts to loosen, resulting in insufficient integrity of the external concrete sleeve and the original foundation, and poor stress coordination performance; the setting of the external sleeve base increases the complexity of the construction process, and the welding joint of the vertical reinforcement and the ring main reinforcement is prone to stress concentration, affecting the structural durability; the thickness of the external concrete sleeve is only 200mm, which is insufficient in terms of rigidity under high load conditions, making it difficult to effectively disperse the load; no special shear-resistant structure is provided, and the shear resistance of the new and old foundation interface is weak, which is prone to relative sliding.

[0006] The reinforcement method for brick strip foundations (such as the "reinforcement of brick strip foundations by adding an external concrete sleeve" described in patent document CN115162433A) has the following problems:

[0007] Only longitudinal and transverse reinforcement is used for reinforcement, without effective anchoring with the upper structure, and the overall stress system is imperfect; similarly, there is a lack of shear-resistant structure, and the stress coordination performance of the new and old interface is poor, making it unsuitable for reinforcement of concrete foundations with high loads.

[0008] Therefore, it is of great practical significance to develop a concrete strip foundation reinforcement technology that is convenient to construct, reasonably stressed, has strong integrity, and excellent shear-resistant performance. SUMMARY

[0009] The application proposes a method for reinforcing a concrete strip foundation by adding new reinforced concrete, which is mainly used to improve the strength, stiffness and durability of the foundation, and ensure the safety and normal use of the whole building.

[0010] To achieve the above-mentioned purpose, the technical solution of the application is as follows:

[0011] The application proposes a method for reinforcing a concrete strip foundation by adding new reinforced concrete, which is mainly used to improve the strength, stiffness and durability of the foundation, and ensure the safety and normal use of the whole building. The new concrete is located on both sides of the original strip foundation, and the strip foundation is widened asymmetrically when the foundation bears eccentric compression, and the strip foundation is widened symmetrically when the foundation bears central compression; the loop main reinforcement of the new concrete is bent, and the lower end is connected with the main reinforcement of the original strip foundation, and the upper end is anchored into the second ground beam; the horizontal reinforcement in the new concrete is welded with the loop main reinforcement, and the horizontal reinforcement and the hoop reinforcement are bound in the new concrete; the loop main reinforcement and the anchoring reinforcement of the new concrete are welded together; the anchoring reinforcement is implanted every 300-400 mm along the direction of the second ground beam, and every 400 mm along the horizontal direction, and the implantation depth of the original strip foundation is not less than 180 mm; the new concrete is divided into separate sections every 1500-2000 mm along the horizontal direction, and is constructed in batches, sections or intervals.

[0012] Further, the concrete strength grade of the new concrete is not less than C30.

[0013] Further, the loop main reinforcement is φ16 reinforcement, and one is arranged every 150 mm along the horizontal direction.

[0014] Further, the horizontal reinforcement bound in the new concrete is all φ12 reinforcement, and the horizontal reinforcement is arranged in φ12@300. The strength of the φ12 reinforcement is moderate, and the arrangement of 300 mm spacing can uniformly transmit the horizontal force, cooperate with the loop main reinforcement to form a stable reinforcement framework, and improve the crack resistance of the new concrete.

[0015] Further, the anchoring reinforcement is all Φ10 reinforcement, and the hot-rolled reinforcement of HPB400 or HRB335 grade is used.

[0016] Further, the minimum thickness of the new concrete is not less than 380 mm.

[0017] Further, the shear key is a concave-convex groove arranged on the contact surface between the original strip foundation and the new concrete, and is arranged in a quincunx shape.

[0018] Further, the first ground beam and the second ground beam are connected into an integral frame through the construction column.

[0019] Further, the contact surface between the new concrete and the original strip foundation is coated with a concrete interface agent before construction.

[0020] A construction method for reinforcing a concrete strip foundation by adding new reinforced concrete, which uses the following steps:

[0021] Step one: First, drill holes on the ground beam according to the design drawings;

[0022] Step two: chisel and clean the strip foundation and the original concrete strip foundation;

[0023] Step three: For the foundation of the widened part of the original foundation cushion, lay a cushion of the same material as the original foundation cushion and compact it;

[0024] Step four: Before binding the steel reinforcement and pouring the new concrete, set up a concave-convex groove on the contact surface between the new and old foundations to form a shear key, arranged in a quincunx pattern to enhance shear resistance; and lay a layer of high-strength grade cement paste or apply a concrete interface agent to increase the bonding force between the new and old concrete foundations;

[0025] Step five: According to the design drawings, drill holes in the original concrete strip foundation and insert anchor steel bars;

[0026] Step six: After bending the ring main reinforcement, connect the lower end to the original strip foundation main reinforcement and anchor the upper end into the ground beam;

[0027] Step seven: After checking the steel reinforcement arrangement, anchor steel bar arrangement, and formwork support, etc., are qualified, pour the new concrete.

[0028] The beneficial effects of the present application are as follows:

[0029] 1: The shear key is used to resist shear force and prevent slippage between new and old concrete. Specifically, the shear key effectively limits the relative displacement of the interface between new and old concrete when subjected to shear force, ensuring good bonding with new and old concrete, thereby ensuring the stability and safety of the structure.

[0030] 2: Reasonable stress, the shear key and connecting device ensure that the new and old foundations work together to avoid uneven settlement.

[0031] 3: The advantage of the present application is that the reinforced concrete strip foundation can effectively improve the strength, stiffness, and durability of the foundation, and the construction period is short, safe and reliable. This method is particularly suitable for reinforcing existing structural strip foundations when the foundation bearing capacity or foundation bottom area size does not meet the requirements. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1This is a schematic plan view of a concrete strip foundation reinforced with reinforced concrete in accordance with the present invention;

[0033] Figure 2 for Figure 1 1-1 cross-sectional view;

[0034] In the figure: 101, original strip foundation; 102, ring main reinforcement; 103, horizontal reinforcement; 104, newly added concrete; 105, ground beam main reinforcement; 106, ground beam stirrups; 107, anchoring reinforcement; 108, newly added concrete cushion; 201, shear key; 202, ground beam one; 203, ground beam two; 204, structural column. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0036] like Figure 1 2, an embodiment of the present invention provides a method of reinforcing a concrete strip foundation by adding reinforced concrete, including a newly added concrete cushion layer 108, an original strip foundation 101, a ring main reinforcement 102, a horizontal reinforcement 103, newly added concrete 104, a ground beam main reinforcement 105, a ground beam stirrup 106, an anchoring reinforcement 107, a shear key 201, a ground beam 1 202, a ground beam 2 203, and a structural column 204.

[0037] The newly added concrete 104 is located on both sides of the original strip foundation 101. When the foundation is subjected to eccentric compression, an asymmetrically widened strip foundation is used. When the foundation is subjected to central compression, a symmetrically widened strip foundation is used. The newly added concrete 104 is bent from the ring main reinforcement 102, and the lower end is connected to the main reinforcement of the original strip foundation 101, and the upper end is anchored into the second ground beam 203. The horizontal steel bars 103 in the newly added concrete 104 are welded together with the ring main reinforcement 102. The horizontal steel bars 103 and stirrups are tied in the newly added concrete 104. The newly added concrete 104 The ring main reinforcement 102 and the anchor steel bar 107 are welded together; the anchor steel bar 107 is implanted every 300mm to 400mm along the direction of the ground beam 203, and the anchor steel bar 107 is implanted every 400mm in the horizontal direction; the depth of the anchor steel bar 107 implanted into the original strip foundation 101 is not less than 180mm; the newly added concrete 104 is divided into separate sections every 1500mm to 2000mm in the horizontal direction, and can be constructed in batches, sections or intervals.

[0038] Preferably, the concrete strength grade of the newly added concrete 104 is not less than C30, so as to ensure that the newly added concrete has sufficient strength to meet the load-bearing requirements of the reinforced foundation and does not cause insufficient strength when bearing loads in conjunction with the original foundation.

[0039] Preferably, the ring main reinforcement 102 is φ16 steel bars, arranged every 150 mm in the horizontal direction. φ16 steel bars have a larger diameter, and when combined with a dense arrangement of 150 mm, they can significantly improve the tensile and bending properties of the newly added concrete, enhancing the overall bearing capacity of the foundation.

[0040] Preferably, all horizontal reinforcement bars 103 tied within the newly added concrete 104 are φ12 steel bars, arranged in a φ12@300 mm spacing. φ12 steel bars have moderate strength, and their 300 mm spacing allows for uniform transmission of horizontal forces. Together with the main ring reinforcement, they form a stable reinforcement framework, improving the crack resistance of the newly added concrete.

[0041] Preferably, the anchor bars 107 are all Φ10 steel bars, using HPB400 or HRB335 grade hot-rolled steel bars. HPB400 or HRB335 grade steel bars are relatively strong, and the Φ10 diameter is suitable for anchoring requirements, ensuring a reliable connection between the ring main bars and the original foundation, and preventing anchor failure when transmitting internal forces.

[0042] Preferably, the minimum thickness of the newly added concrete 104 is not less than 380 mm. A thicker newly added concrete layer can provide a larger compressive area and stiffness, effectively distributing the upper load and adapting to the bearing requirements under high load conditions.

[0043] The above-mentioned reinforced concrete strip foundation reinforcement method and its construction method adopt the following steps:

[0044] Step 1: First, drill holes on the ground beam according to the design drawing requirements.

[0045] Step 2: Chisel and scrub the concrete ground beam and original concrete strip foundation clean.

[0046] Step 3: Lay a cushion layer made of the same material as the original foundation cushion layer on the widened part of the original foundation cushion layer and compact it.

[0047] Step 4: Before adding new concrete, tying steel bars and pouring concrete, set concave and convex grooves on the contact surface of the new and old foundations of the original strip foundation to form shear keys, arranged in a plum blossom shape to enhance shear resistance; and lay a layer of high-strength cement slurry or apply concrete interface agent to increase the bonding strength of the concrete foundations between the new and old structures.

[0048] Step 5: Drill holes in the original concrete strip foundation according to the design drawings and implant anchor steel bars.

[0049] Step 6: After bending the ring main reinforcement, connect the lower end to the original strip foundation main reinforcement and anchor the upper end into the ground beam.

[0050] Step 7: Before pouring the additional concrete, after the steel bar arrangement, anchor steel bar arrangement and formwork support have been inspected and qualified, the concrete pouring construction can be carried out.

[0051] The above are only preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Replacement may be partial structure, device, method step replacement, or a complete technical solution. Equivalent replacement or modification based on the technical solution and inventive concept of the present invention shall be covered by the scope of protection of the present invention.

Claims

1. A method of reinforcing a concrete strip foundation by adding reinforced concrete, comprising a newly added concrete cushion, the original strip foundation, ring main reinforcement, horizontal reinforcement, newly added concrete, ground beam main reinforcement, ground beam stirrups, anchor reinforcement, shear keys, a first ground beam, a second ground beam, and structural columns, characterized in that: The newly added concrete is located on both sides of the original strip foundation. When the foundation is subjected to eccentric compression, an asymmetrically widened strip foundation is adopted. When the foundation is subjected to central compression, a symmetrically widened strip foundation is adopted. After the newly added concrete is bent by the ring main reinforcement, the lower end is connected to the original strip foundation main reinforcement, and the upper end is anchored into the second ground beam. The horizontal steel bars in the newly added concrete are welded together with the ring main reinforcement, and the horizontal steel bars and stirrups are tied in the newly added concrete. The ring main reinforcement and the anchor steel bars of the newly added concrete are welded together. The anchor steel bars are implanted every 300mm to 400mm along the second ground beam and every 400mm in the horizontal direction, and the depth of implantation in the original strip foundation is not less than 180mm. The newly added concrete is divided into separate sections every 1500mm to 2000mm in the horizontal direction, and construction is carried out in batches, sections or intervals.

2. The method of reinforcing a concrete strip foundation by adding reinforced concrete according to claim 1, characterized in that: The concrete strength grade of the newly added concrete is not lower than C30.

3. The method of reinforcing a concrete strip foundation by adding reinforced concrete according to claim 1, characterized in that: The main reinforcement of the ring is φ16 steel bar, which is arranged every 150mm in the horizontal direction.

4. The method of reinforcing a concrete strip foundation by adding reinforced concrete according to claim 1, characterized in that: The horizontal reinforcement tied into the newly added concrete is all φ12 steel, arranged at φ12@300mm. φ12 steel bars have moderate strength, and the 300mm spacing allows for even transmission of horizontal forces. Together with the main ring reinforcement, they form a stable reinforcement framework, improving the crack resistance of the newly added concrete.

5. The method of reinforcing a concrete strip foundation by adding reinforced concrete according to claim 1, characterized in that: The anchoring steel bars are all Φ10 steel bars, and are hot-rolled steel bars of HPB400 or HRB335 grade.

6. The method of reinforcing a concrete strip foundation by adding reinforced concrete according to claim 1, characterized in that: The minimum thickness of the newly added concrete shall not be less than 380mm.

7. The method of reinforcing a concrete strip foundation by adding reinforced concrete according to claim 1, characterized in that: The shear keys are concave and convex grooves provided on the contact surface between the original strip foundation and the newly added concrete, and are arranged in a plum blossom shape.

8. The method of reinforcing a concrete strip foundation by adding reinforced concrete according to claim 1, characterized in that: The first ground beam and the second ground beam are connected to form an integral frame through structural columns.

9. The method of reinforcing a concrete strip foundation by adding reinforced concrete according to claim 1, characterized in that: The contact surface between the newly added concrete and the original strip foundation is coated with a concrete interface agent before construction.

10. A construction method for reinforcing a concrete strip foundation by adding reinforced concrete according to any one of claims 1 to 9, comprising the following steps: Step 1: First, drill holes on the ground beam according to the design drawings; Step 2: Chisel and scrub the concrete ground beam and the original concrete strip foundation clean; Step 3: Lay a cushion layer made of the same material as the original foundation cushion layer on the widened part of the original foundation cushion layer and tamp it down; Step 4: Before adding concrete, tying the reinforcement and pouring the concrete, the contact surface of the new and old strip foundations is provided with concave and convex grooves in a plum blossom pattern to form shear keys to enhance shear resistance. A layer of high-strength cement slurry or a concrete interface agent is applied to increase the bonding strength of the concrete foundations between the new and old structures. Step 5: Drill holes in the original concrete strip foundation according to the design drawings and implant anchor steel bars; Step 6: After bending the ring main reinforcement, connect the lower end to the original strip foundation main reinforcement and anchor the upper end into the ground beam; Step 7: Before pouring the additional concrete, after the steel bar arrangement, anchor steel bar arrangement and formwork support have been inspected and qualified, the concrete pouring construction can be carried out.

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