Basement wall waterproofing and supporting combined structure and construction method thereof
By combining concrete cantilever piles and micro steel pipe piles with waterproof guide walls and drainage ditches, the problems of cantilever pile removal, anchored pile layout restrictions, and internal support space occupation were solved, achieving efficient and undisturbed foundation pit support.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- BEIJING LIUJIAN CONSTR GRP
- Filing Date
- 2026-01-08
- Publication Date
- 2026-06-12
AI Technical Summary
Existing foundation pit support technologies have several drawbacks in narrow sites, including the need to remove the capping beam for cantilever piles, which affects above-ground buildings; the inability to implement anchored piles due to red line restrictions; and the space occupied by internal support systems, which affects efficiency.
The system employs a combination of concrete cantilever piles and micro steel pipe piles, along with waterproof guide walls and drainage ditches, to form an integrated waterproof system that avoids the removal of the cap beam and is suitable for construction in narrow spaces.
It improves construction efficiency, reduces disturbance to surrounding buildings, ensures smooth construction, is suitable for narrow sites, avoids space occupation, and achieves efficient earthwork and main structure construction.
Smart Images
Figure CN122190263A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of urban renewal and renovation technology of old bungalows and courtyards, and specifically relates to a combination structure for waterproofing and support of basement walls and its construction method. Background Technology
[0002] Urban renewal has become a significant direction for urban development in recent years, with the protection, renovation, and functional regeneration of old courtyard houses being a key component. When renovating these courtyard houses, in addition to meeting protective repair requirements, underground space development is often involved to improve overall land use efficiency. In such renovation scenarios, the foundation pit is often adjacent to existing low-rise brick-and-wood structures. These old buildings have shallow foundations and weak deformation resistance, making them extremely sensitive to foundation pit deformation. Insufficient support rigidity or significant construction disturbance can easily lead to settlement, cracking, or even local instability in nearby buildings. Furthermore, narrow alleyways cannot provide sufficient operating space for large machinery, significantly restricting the layout of support structures, the selection of construction procedures, and the entry and exit of equipment, thus placing higher demands on construction organization and support schemes.
[0003] Among existing foundation pit support technologies, cantilever piles, anchored piles, and internally braced piles are commonly used for foundation pits of relatively shallow or medium depth. Cantilever piles have a simple structure and do not occupy additional space inside or outside the pit, making them suitable for sites with limited surrounding resources. However, the top of the cantilever pile and its corresponding capping beam can affect the construction of the above-ground building structure, requiring the capping beam and pile top to be broken up and demolished in the later stages of construction. Anchored piles perform well in displacement control and can be used for deeper foundation pits, but the anchor installation requires sufficient extension space outside the pit. Older single-story courtyard projects are often located where buildings and roads are close to the boundary line, making it impossible to install anchor cables outside the pit, thus rendering this method infeasible. Internally braced systems have high rigidity and can control foundation pit deformation, but require multiple steel supports inside the pit, which severely occupies limited underground space, hindering earthwork excavation and subsequent underground structure construction. Furthermore, the process of dismantling and replacing supports is cumbersome and cannot meet the efficient construction needs of narrow courtyard sites.
[0004] In summary, the existing technologies have the following technical problems and drawbacks: cantilever piles require the demolition of the capping beam and pile top in the later stages of construction; anchored piles are limited by the boundary line and surrounding buildings and cannot be implemented; and internal support systems occupy a large amount of space, affecting construction efficiency. Especially when the foundation pit shape is irregular, the distance to surrounding buildings is less than 2 meters, the road width is limited, and the construction site is extremely confined, the above-mentioned traditional support methods are difficult to balance structural safety, construction feasibility, and cost control. Summary of the Invention
[0005] The purpose of this invention is to provide a combined structure for waterproofing and support of basement walls and its construction method. The technical problems to be solved are: cantilever piles require the breaking and demolition of the cap beam and the top of the pile in the later stage of construction; anchored piles are limited by the red line and surrounding buildings and cannot be implemented; and the internal support system occupies a lot of space and affects construction efficiency.
[0006] The technical solution of this invention to solve the above-mentioned technical problems is as follows: A combined structure for waterproofing and support of basement walls, wherein the outer side of the basement wall is adjacent to an existing building; the support includes concrete cantilever piles and micro steel pipe piles; the concrete cantilever piles are arranged on the outer side of the basement wall, and the distance between the top of the concrete cantilever pile and the ground elevation is a predetermined height difference; a first capping beam is provided at the top of the concrete cantilever pile, and the first capping beam connects adjacent concrete cantilever piles; a retaining wall is provided between the concrete cantilever piles; the micro steel pipe piles are arranged around the concrete cantilever piles, and the lower part of the micro steel pipe pile and the top of the concrete cantilever pile form an overlapping section; a second capping beam is provided at the top of the micro steel pipe piles, and the second capping beam connects adjacent micro steel pipe piles; a retaining wall is provided between the micro steel pipe piles; the basement wall includes an outer basement wall and a waterproof guide wall, the waterproof guide wall is adjacent to the concrete cantilever piles, and a first waterproof layer is provided between the outer basement wall and the waterproof guide wall.
[0007] The basement wall waterproofing and support combination structure of the present invention, as described above, further includes a raft foundation at the bottom of the basement wall, a concrete pad below the raft foundation, and a second waterproof layer between the raft foundation and the concrete pad. The first waterproof layer and the second waterproof layer are integrally continuous waterproof layers.
[0008] The basement wall waterproofing and support combination structure described above further includes a drainage ditch, which is located at the lower part of the waterproof guide wall and filled with gravel.
[0009] The basement wall waterproofing and support combination structure of the present invention, as described above, further includes the following: the distance between the outer side of the basement wall and the existing building is between 1 meter and 2 meters; the predetermined height difference is between 1 meter and 2 meters; and the length of the overlapping section is between 1.2 meters and 1.8 meters.
[0010] The basement wall waterproofing and support combination structure described above further includes a retaining wall between piles formed by construction using steel mesh and fine stone concrete.
[0011] The basement wall waterproofing and support combination structure of the present invention, as described above, further includes a first cap beam and a second cap beam connected by pre-embedded connecting steel bars or post-installed steel bars.
[0012] The basement wall waterproofing and support combination structure of the present invention, as described above, further includes concrete cantilever piles with a diameter of 600 mm to 900 mm; and micro steel pipe piles with a diameter of 80 mm to 120 mm, wherein the interior of the micro steel pipe piles is filled with cement grout.
[0013] This invention also provides a construction method for a combined waterproofing and support structure for basement walls, comprising the following steps: Step 1: Construct concrete cantilever piles before excavating the foundation pit, and construct the first capping beam at the top of the concrete cantilever piles; construct micro steel pipe piles between the concrete cantilever piles and the existing building, and construct the second capping beam at the top of the concrete cantilever piles. Step 2: Excavate the foundation pit. During the excavation process, construct the retaining wall from top to bottom. The retaining wall is formed between the micro steel pipe piles using steel mesh and fine stone concrete, and between the concrete cantilever piles using steel mesh and fine stone concrete. Step 3: Construct a concrete cushion layer at the bottom of the foundation pit, construct a waterproof guide wall perpendicular to the concrete cushion layer inside the concrete cantilever pile, and lay a waterproof layer on top of the concrete cushion layer and inside the waterproof guide wall; preferably, before constructing the waterproof guide wall, the excavation of a drainage ditch is also included, and the drainage ditch is filled with gravel.
[0014] Step 4: Construct a raft foundation above the concrete cushion layer, and construct the basement exterior wall inside the waterproof guide wall. The raft foundation and the basement exterior wall are perpendicular to each other.
[0015] The beneficial effects of this invention are: 1. Avoids the complex work of dismantling the cantilever pile cap beam later, improving construction efficiency. There is a predetermined height difference between the top of the concrete cantilever pile and the ground elevation. The cantilever pile and the corresponding cap beam will not affect the construction and layout of the subsequent above-ground buildings, eliminating the need for large-scale demolition, reducing noise, vibration and disturbance to surrounding buildings, and improving construction efficiency and safety.
[0016] 2. Achieve constructability in narrow site conditions and improve the flexibility of construction organization. Cantilever piles and micro steel pipe piles can be implemented in the limited space of 1 to 2 meters between existing buildings and cantilever piles, avoiding the limitation of conventional anchor cable support that cannot be constructed due to insufficient red line or building spacing, making this structure suitable for extremely limited construction spaces such as old courtyards.
[0017] 3. The construction process is smooth and does not occupy underground space, ensuring the efficiency of earthwork and main structure construction. This solution does not require an internal support system, avoiding the occupation of pit space and enabling smooth and efficient earthwork excavation and raft foundation and exterior wall construction. It is particularly suitable for projects with narrow courtyards and tight schedules.
[0018] In summary, this invention solves the technical problems of cantilever piles requiring the demolition of the capping beam and pile top in the later stages of construction; anchored pile drives being limited by the boundary line and surrounding buildings; and internal support systems occupying a large amount of space and affecting construction efficiency. Attached Figure Description
[0019] The advantages of the present invention, both above and / or other aspects, will become clearer and more readily understood through the following detailed description taken in conjunction with the accompanying drawings, which are merely illustrative and do not limit the invention, wherein: Figure 1 This is a schematic diagram of the existing building and foundation pit layout according to an embodiment of the present invention; Figure 2 This is a schematic diagram of a combined waterproofing and support structure for basement walls according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the layout of a concrete cantilever pile and a micro steel pipe pile according to an embodiment of the present invention; Figure 4 for Figure 3 A magnified view of the area on the right; Figure 5 A flowchart illustrating the construction method for a combined waterproofing and support structure for basement walls.
[0020] The attached diagram lists the components represented by each number as follows: 1. Concrete cantilever pile, 2. First capping beam, 3. Micro steel pipe pile, 4. Second capping beam, 5. Waterproof guide wall, 6. Basement exterior wall, 7. Drainage ditch, 8. Raft foundation, 9. Concrete cushion layer, 10. Second waterproof layer, 11. First waterproof layer, 12. Existing building, 13. Foundation pit. Detailed Implementation
[0021] In the following description, embodiments of the basement wall waterproofing and support combination structure and its construction method of the present invention will be described with reference to the accompanying drawings.
[0022] The embodiments described herein are specific implementations of the present invention, used to illustrate the concept of the invention, and are illustrative and exemplary, and should not be construed as limiting the implementation or scope of the invention. In addition to the embodiments described herein, those skilled in the art can employ other obvious technical solutions based on the content disclosed in the claims and specification of this application. These technical solutions include those that make any obvious substitutions and modifications to the embodiments described herein.
[0023] The accompanying drawings in this specification are schematic diagrams to aid in illustrating the concept of the invention, and schematically show the shapes of the various parts and their interrelationships. Please note that, in order to clearly demonstrate the structure of the components in the embodiments of the invention, the drawings are not drawn to the same scale. The same reference numerals are used to indicate the same parts.
[0024] Figure 1 This application describes a specific renovation scenario involving a single-story courtyard house. The excavation pit 13 is adjacent to existing low-rise brick-and-wood buildings on the north, west, and east sides, with a lane road to the south. In this scenario, sufficient operating space for large machinery is limited, significantly restricting the layout of the support structure, the selection of construction procedures, and the movement of equipment. The technical solution presented here can be applied to this renovation scenario, as well as similar scenarios (such as those with existing buildings on all four sides). Furthermore, due to limited site space, it is impossible to leave a construction trench during the foundation raft slab construction. Because the space between the basement exterior walls and the concrete cantilever piles is narrow, there is no space available to construct a waterproofing layer on the outside of the basement exterior walls after their completion.
[0025] The following combination Figures 2 to 4 This invention describes a combined waterproofing and support structure for basement walls according to one embodiment of the present invention. The outer side of the basement wall is adjacent to the existing building 12. The present invention is particularly applicable to construction scenarios where the distance between the outer side of the basement wall and the existing building 12 is between 1 meter and 2 meters. The support includes concrete cantilever piles 1 and micro steel pipe piles 3. A concrete cantilever pile 1 is installed on the outer side of the basement wall. The distance between the top of the concrete cantilever pile 1 and the ground elevation is a predetermined height difference, preferably between 1 meter and 2 meters. A first capping beam 2 is provided at the top of the concrete cantilever pile 1, and the first capping beam 2 connects adjacent concrete cantilever piles 1. A retaining wall is provided between the concrete cantilever piles 1. In this embodiment, the concrete cantilever pile 1 can be constructed by bored pile method, and the hole forming method can be rotary drilling, impact drilling or manual hole forming. The concrete strength grade of the pile body can be C25 to C30. In a specific embodiment, the concrete cantilever pile diameter is 800 mm, the pile spacing is 1400 mm to 1500 mm, the hole depth is 11.25 m, and the pile length is 10 m. The first capping beam is a rectangular capping beam of 1000*600 mm.
[0026] Miniature steel pipe piles 3 are installed around the concrete cantilever piles 1, with an overlapping section between the lower part of the miniature steel pipe piles 3 and the top of the concrete cantilever piles 1. A second capping beam 4 is installed at the top of the miniature steel pipe piles 3, connecting adjacent miniature steel pipe piles 3. Inter-pile retaining walls are installed between the miniature steel pipe piles 3. During construction, the pile holes can be formed using a small hydraulic drilling rig or a portable drilling rig, suitable for construction in confined spaces. In one specific embodiment, the miniature steel pipe piles have a diameter of 100 mm, a pile spacing of 1000 mm, a pile length of 3 meters, an inner diameter of 89 mm, a wall thickness of 4.0 mm, and the inner cavity of the steel pipe is filled with cement grout. The overlapping section helps to form a mechanical superposition of two support systems in the depth direction, enhancing the pile stiffness and reducing horizontal displacement after excavation. Preferably, the overlapping section can be set to 1.2 meters to 1.8 meters to balance construction feasibility and mechanical performance.
[0027] Due to the limited space between the basement exterior wall and the concrete cantilever piles, there is insufficient space to construct a waterproofing layer on the outside of the basement exterior wall after its construction is completed. Therefore, the above embodiment needs further improvement. The basement wall includes an exterior wall 6 and a waterproof guide wall 5. The waterproof guide wall 5 is adjacent to the concrete cantilever piles 1. A first waterproofing layer 11 is provided between the exterior wall 6 and the waterproof guide wall 5. During construction, the waterproof guide wall is directly constructed against the inner side of the concrete cantilever piles, and the waterproofing layer is applied to the inner side of the waterproof guide wall. The waterproof guide wall serves as the outer support surface for the underground exterior wall structure construction. In a specific embodiment of the combined waterproofing and support structure for the basement wall, the bottom of the basement wall is a raft foundation 8, below which is a concrete cushion layer 9. A second waterproofing layer 10 is provided between the raft foundation 8 and the concrete cushion layer 9. The first waterproofing layer 11 and the second waterproofing layer 10 are integrally continuous waterproofing layers. During construction, after the raft foundation and waterproof guide wall are completed, a waterproof layer is applied integrally and continuously to the raft foundation and waterproof guide wall. Then, the basement exterior walls adjacent to the waterproof guide wall are constructed. The materials for the first waterproof layer 11 and the second waterproof layer 10 can be selected from: polymer self-adhesive membrane or SBS modified bitumen membrane. This forms an integrated waterproof system for the basement walls, effectively preventing groundwater from seeping in through the foundation slab and side walls, thus improving the long-term durability of the basement.
[0028] In a specific embodiment of the combined waterproofing and support structure for basement walls, a drainage ditch 7 is also included. The drainage ditch 7 is located at the lower part of the waterproof guide wall 5 and is filled with crushed stone. The drainage ditch 7 can adopt a trench structure with a width of 200 mm to 300 mm and a depth of 300 mm to 500 mm. The particle size of the crushed stone should preferably be 20 mm to 40 mm to ensure good permeability. The drainage ditch can be arranged around the perimeter of the foundation pit to form a ring drainage system, leading to a temporary sump for subsequent pumping construction.
[0029] In a specific embodiment of a combined waterproofing and support structure for basement walls, the retaining wall between piles is formed by constructing a steel mesh and fine aggregate concrete. The retaining wall typically uses fine aggregate concrete with a thickness of 80 mm to 120 mm, and the steel mesh can be made of φ6 to φ8 steel bars welded together with a mesh spacing of 50 mm to 100 mm to improve the shear strength and surface stability of the retaining wall.
[0030] In a specific embodiment of the combined structure for waterproofing and support of basement walls, the first cap beam 2 and the second cap beam 4 are connected by pre-embedded connecting steel bars or post-installed steel bars.
[0031] In a specific embodiment of a combined waterproofing and support structure for basement walls, the concrete cantilever pile 1 has a diameter of 600 mm to 900 mm; the micro steel pipe pile 3 has a diameter of 80 mm to 120 mm, and the interior of the micro steel pipe pile 3 is filled with cement grout.
[0032] Combination Figure 5 This invention describes a construction method for a basement wall waterproofing and support combination structure according to an embodiment of the present invention, comprising the following steps: Step 1: Construct concrete cantilever piles 1 before excavating the foundation pit 14; construct the first capping beam 2 on top of the concrete cantilever piles 1; construct micro steel pipe piles 3 between the concrete cantilever piles 1 and the existing building 12; and construct the second capping beam 4 on top of the concrete cantilever piles 1. Step 2: Excavate the foundation pit 14. During the excavation process, the retaining wall is constructed from top to bottom. The retaining wall between the micro steel pipe piles 3 is formed by steel mesh and fine stone concrete, and the retaining wall between the concrete cantilever piles 1 is formed by steel mesh and fine stone concrete. Step 3: Concrete cushion layer 9 is constructed at the bottom of foundation pit 14, and waterproof guide wall 5 is constructed perpendicular to concrete cushion layer 9 on the inner side of concrete cantilever pile 1. A waterproof layer is laid on top of concrete cushion layer 9 and on the inner side of waterproof guide wall 5. Preferably, before the construction of waterproof guide wall 5, the excavation of drainage ditch 7 is also included, and the drainage ditch 7 is filled with crushed stone.
[0033] Step 4: Construct the raft foundation 8 above the concrete cushion layer 9, and construct the basement exterior wall 6 inside the waterproof guide wall 5. The raft foundation 8 and the basement exterior wall 6 are perpendicular to each other.
[0034] The above-mentioned technical solution of the present invention adopts a combination of concrete cantilever piles and micro steel pipe piles, and a comprehensive support method using waterproof guide walls for support, which effectively solves many problems such as lack of construction trench, displacement deformation, and limited working space.
[0035] The technical features disclosed above are not limited to the combinations of the disclosed features with other features. Those skilled in the art can also make other combinations of the technical features according to the purpose of the invention to achieve the purpose of the invention.
Claims
1. A combined structure for waterproofing and supporting basement walls, characterized in that, The outer side of the basement wall is adjacent to the existing building (12); the support includes concrete cantilever piles (1) and micro steel pipe piles (3); The concrete cantilever pile (1) is set on the outside of the basement wall, and the distance between the top of the concrete cantilever pile (1) and the ground elevation is a predetermined height difference; a first capping beam (2) is set on the top of the concrete cantilever pile (1), and the first capping beam (2) connects the adjacent concrete cantilever pile (1); a pile retaining wall is set between the concrete cantilever piles (1). The miniature steel pipe pile (3) is arranged around the concrete cantilever pile (1), and the lower part of the miniature steel pipe pile (3) and the top of the concrete cantilever pile (1) are overlapping sections; a second capping beam (4) is provided on the top of the miniature steel pipe pile (3), and the second capping beam (4) connects the adjacent miniature steel pipe piles (3); a pile retaining wall is provided between the miniature steel pipe piles (3); The basement wall includes an outer basement wall (6) and a waterproof guide wall (5). The waterproof guide wall (5) is adjacent to the concrete cantilever pile (1). A first waterproof layer (11) is provided between the outer basement wall (6) and the waterproof guide wall (5).
2. The combined waterproofing and support structure for basement walls according to claim 1, characterized in that, The basement wall is supported by a raft foundation (8) at its bottom, and a concrete cushion layer (9) is placed below the raft foundation (8). A second waterproof layer (10) is provided between the raft foundation (8) and the concrete cushion layer (9). The first waterproof layer (11) and the second waterproof layer (10) are an integral waterproof layer.
3. The combined structure for waterproofing and support of basement walls and its construction method according to claim 1, characterized in that, It also includes a drainage ditch (7), which is located at the lower part of the waterproof guide wall (5) and is filled with gravel.
4. The combined waterproofing and support structure for basement walls according to claim 1, characterized in that, The distance between the outer side of the basement wall and the existing building (12) is between 1 meter and 2 meters; the predetermined height difference is between 1 meter and 2 meters; and the length of the overlapping section is between 1.2 meters and 1.8 meters.
5. The combined structure for waterproofing and support of basement walls according to claim 1, characterized in that, The retaining wall between piles is formed by constructing a retaining wall using steel mesh and fine aggregate concrete.
6. The combined waterproofing and support structure for basement walls according to claim 1, characterized in that, The first crown beam (2) and the second crown beam (4) are connected by pre-embedded connecting steel bars or post-installed steel bars.
7. The combined waterproofing and support structure for basement walls according to claim 1, characterized in that, The concrete cantilever pile (1) has a pile diameter of 600 mm to 900 mm; the micro steel pipe pile (3) has a pile diameter of 80 mm to 120 mm, and the interior of the micro steel pipe pile (3) is filled with cement grout.
8. A construction method for a combined waterproofing and support structure for basement walls, characterized in that, Includes the following steps: Step 1: Construct concrete cantilever piles (1) before excavating the foundation pit (14), construct the first capping beam (2) on the top of the concrete cantilever piles (1); construct micro steel pipe piles (3) between the concrete cantilever piles (1) and the existing building (12), and construct the second capping beam (4) on the top of the concrete cantilever piles (1). Step 2, excavate the foundation pit (14), and carry out the wall construction from top to bottom during the excavation process. The wall is formed by steel mesh and fine stone concrete between the micro steel pipe piles (3) and between the concrete cantilever piles (1). Step 3: Construct a concrete cushion layer (9) at the bottom of the foundation pit (14), construct a waterproof guide wall (5) perpendicular to the concrete cushion layer (9) on the inside of the concrete cantilever pile (1), and lay a waterproof layer on the top of the concrete cushion layer (9) and on the inside of the waterproof guide wall (5). Step 4: Construct a raft foundation (8) above the concrete cushion layer (9), and construct the basement exterior wall (6) inside the waterproof guide wall (5). The raft foundation (8) and the basement exterior wall (6) are perpendicular to each other.
9. The construction method of the combined waterproofing and support structure for basement walls according to claim 8, characterized in that, Before the construction of the waterproof guide wall (5), the excavation of the drainage ditch (7) is also included, and the drainage ditch (7) is filled with gravel.