Foundation pit supporting structure of low-clearance adjacent viaduct pile
By using a foundation pit support structure that combines plain concrete diaphragm walls and bored piles with internal bracing under the viaduct, the problems of equipment applicability and safety reliability of the retaining structure for dewatering control in the area adjacent to the viaduct were solved, achieving both simplicity and safety in construction.
Patent Information
- Application Number
- CN202423300970.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-31
- Publication Date
- 2025-12-02
- Estimated Expiration
- 2034-12-31
AI Technical Summary
In areas adjacent to viaducts, existing equipment for constructing rainwater control retaining structures is poorly suited and has low safety and reliability. Especially under low clearance conditions, conventional equipment such as high-pressure jet grouting piles and MJS are unreliable, and triaxial mixing piles, TRD or CSM equipment are not suitable. Furthermore, construction may affect the safety of surrounding bridge piles.
The foundation pit support structure adopts a combination of plain concrete diaphragm walls and bored piles with internal bracing. The plain concrete diaphragm walls are vertically set on the sides of the viaduct pile caps and bridge piles. The bored piles are spaced apart on the outside of the diaphragm walls and penetrate through the soft soil layer to insert into the impermeable rock layer. The internal bracing is set between the bored piles, and the combination of interlocking pipe joints and milling joints optimizes the flow of groundwater around the piles.
It improved the equipment applicability and construction safety of the rainwater control retaining structure, reduced the impact on the surrounding environment, ensured the safety of the foundation pit excavation and the surrounding viaduct, and controlled ground settlement.
Smart Images
Figure CN223620929U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of building engineering technology and relates to a foundation pit support structure. Background Technology
[0002] Foundation pit support refers to the temporary support, reinforcement, protection, and groundwater control measures adopted for foundation pits to protect the construction of underground main structures and the safety of the surrounding environment. Specific details can be found in the "JGJ120-2012 Technical Specification for Foundation Pit Support". Whether to use a support structure for foundation pit excavation, and what type of support structure to use, should be determined through a comprehensive economic, technical, and environmental analysis and comparison, based on the surrounding environment, excavation depth, engineering geological and hydrogeological conditions, construction conditions, construction season, and local engineering experience. In foundation pit projects with high groundwater levels, poor geological conditions, and large excavation depths, bored piles, diaphragm walls, and interlocking piles are commonly used support structures.
[0003] During the excavation of the foundation pit, in order to ensure the safety of earthwork excavation, it is necessary to ensure that the groundwater level in the foundation pit is 1.5m below the excavation surface. Therefore, it is necessary to install dewatering wells in the pit. Thus, when there are important buildings and structures around the foundation pit and the surrounding strata are sensitive to heavy rainfall, it is necessary to strictly control the dewatering, that is, to adopt a bottom-falling curtain to cut off the hydraulic connection between the inside and outside of the pit, and to carry out decompression dewatering only in the pit. When constructing diaphragm walls and bored piles under viaducts, the low clearance of the bridge deck necessitates appropriate modifications to the equipment to meet the height requirements. In the area adjacent to the viaduct where dewatering is controlled, on the one hand, to minimize the impact of dewatering on the surrounding environment, the dewatering curtain for the foundation pit needs to be a bottom-falling curtain. The quality requirements for bottom-falling curtains are high. Existing technologies such as high-pressure jet grouting piles and MJS have poor reliability, and existing equipment such as triaxial mixing piles, TRD, or CSM are not suitable for low clearance, resulting in poor equipment applicability. On the other hand, the potential for borehole collapse during the construction of the foundation pit retaining structure needs to be considered, as it may have an adverse impact on the surrounding bridge piles. Conventional diaphragm wall technology has a significant impact on bridge piles after borehole collapse, resulting in low safety and reliability. Utility Model Content
[0004] To address the issues of poor applicability and low safety and reliability of construction equipment for current dewatering control retaining structures adjacent to viaduct areas, as described in the background art, this utility model proposes a low-clearance foundation pit support structure adjacent to viaduct piles.
[0005] This utility model includes a plain concrete diaphragm wall, internal supports, and multiple bored piles. The plain concrete diaphragm wall is vertically installed on the side of the viaduct pile cap and the viaduct piles. The bored piles are spaced apart on the outside of the plain concrete diaphragm wall, and internal supports are installed between the bored piles.
[0006] Furthermore, both the plain concrete underground continuous wall and the bored piles are located below the soft soil layer, and their positions do not exceed the projection line of the viaduct deck.
[0007] Furthermore, the plain concrete diaphragm wall passes through soft soil and sand layers in sequence and inserts into impermeable rock layers.
[0008] Furthermore, the bored pile penetrates the soft soil layer and inserts into the sand layer.
[0009] Furthermore, the plain concrete diaphragm wall is equipped with a lock-type pipe joint.
[0010] Furthermore, the plain concrete diaphragm wall is equipped with milling joints.
[0011] Furthermore, the distance between the plain concrete diaphragm wall and the viaduct pile cap is not less than 1.5D, where D is the bottom diameter of the bridge pile; the distance between the plain concrete diaphragm wall and the viaduct pile is not less than 1.5D, where D is the bottom diameter of the bridge pile.
[0012] Furthermore, the spacing between the bored piles and the plain concrete diaphragm wall is 200-300mm.
[0013] Furthermore, the spacing between the drilled piles is 150-250mm.
[0014] Furthermore, the internal support includes multiple steel supports or multiple concrete supports arranged horizontally between the bored piles.
[0015] Compared with the prior art, the present invention provides a low-clearance foundation pit support structure adjacent to viaduct piles. A plain concrete diaphragm wall is vertically installed on the sides of the viaduct pile foundation cap and the viaduct piles. Multiple bored piles are installed on the outside of the plain concrete diaphragm wall, with internal supports between the bored piles. The foundation pit support structure is simple, easy to construct, requires minimal construction equipment, and has a controllable impact on the surrounding environment during construction. It ensures the safety of foundation pit excavation, the safety of the surrounding viaduct, and controllable ground settlement. It solves the problems of poor applicability of construction equipment and low safety reliability of current dewatering control retaining structures in areas adjacent to viaducts.
[0016] The foundation pit support structure of this utility model is suitable for construction environments where there are low clearances under elevated bridges and adjacent bridge piles around the foundation pit. It is also suitable for environments where the height of construction operations is controlled by high-voltage lines or other factors, or for environments where important buildings or structures are protected around the foundation pit. In particular, when the foundation pit project has a large excavation depth and a high groundwater level, and the important buildings and structures around it are sensitive to collapse and precipitation, the use of this foundation pit support structure can effectively improve the safety of the surrounding environment and the safety of foundation pit construction. Attached Figure Description
[0017] Figure 1 This is a cross-sectional layout diagram of the foundation pit support structure.
[0018] Figure 2 This is a plan view of the foundation pit support structure.
[0019] Explanation of reference numerals in the attached drawings: 1 viaduct, 1-1 viaduct pier, 1-2 viaduct pier cap, 1-3 viaduct deck, 1-4 viaduct deck projection line, 1-5 bridge pile foundation, 2 bored pile, 3 plain concrete diaphragm wall, 3-1 interlocking pipe joint, 3-2 milling joint, 4 internal support, 5-1 soft soil layer, 5-2 sand layer, 5-3 impermeable rock layer, 5-4 rock layer boundary line. Detailed Implementation
[0020] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit the scope of this application. The positional relationships described in the embodiments are consistent with those shown in the accompanying drawings.
[0021] A low-clearance foundation pit support structure adjacent to viaduct piles, the cross-sectional layout of which is shown in the figure. Figure 1 As shown, the floor plan is as follows Figure 2 As shown, it consists of a plain concrete diaphragm wall 3, internal supports 4, and multiple bored piles 2. The plain concrete diaphragm wall 3 is vertically installed on the side of the viaduct pile cap 1-2 and the viaduct pile 1-1. The bored piles 2 are spaced apart on the outside of the plain concrete diaphragm wall 3, and internal supports 4 are installed between the bored piles 2.
[0022] Specifically, such as Figure 1 As shown, the plain concrete underground continuous wall 3 and the bored pile 2 are both set below the soft soil layer 5-1, and their positions do not exceed the projection line 1-4 of the viaduct deck.
[0023] More specifically, such as Figure 1 As shown, the plain concrete diaphragm wall 3 passes through the soft soil layer 5-1 and the sand layer 5-2 in sequence and inserts into the impermeable rock layer 5-3. The bored pile 2 passes through the soft soil layer 5-1 and inserts into the sand layer 5-2.
[0024] Specifically, such as Figure 2 As shown, a lock-joint pipe joint 3-1 is installed inside the plain concrete diaphragm wall 3. It should be noted that the lock-joint pipe is a circular steel pipe, which is lowered simultaneously with the reinforcing cage during the first-stage trenching stage. It is removed after the first-stage diaphragm wall concrete is poured, thus forming an arc at the end of the first-stage diaphragm wall. When the second-stage concrete is poured, it can form an extended groundwater bypass route.
[0025] Specifically, such as Figure 2 As shown, a milling joint 3-2 is installed inside the plain concrete diaphragm wall 3. It should be noted that the milling joint 3-2 is a special diaphragm wall trenching device, such as a twin-wheel milling machine. When trenching the second-phase diaphragm wall, a twin-wheel milling machine is used to cut 20-30cm of concrete to form a serrated joint, thereby lengthening the groundwater flow path.
[0026] Specifically, such as Figure 2 As shown, the inner support 4 includes multiple steel supports or multiple concrete supports arranged horizontally between the bored piles 2.
[0027] Preferably, regarding their placement, the distance between the plain concrete diaphragm wall 3 and the viaduct pile cap 1-2 is not less than 1.5D, where D is the bottom diameter of the bridge pile 1-5; the distance between the plain concrete diaphragm wall 3 and the viaduct pile 1-1 is not less than 1.5D, where D is the bottom diameter of the bridge pile 1-5. The spacing between the bored piles 2 and the plain concrete diaphragm wall 3 is 200-300mm. The spacing between the bored piles 2 is 150-250mm.
[0028] The construction method for the foundation pit support structure is as follows:
[0029] Construction of Plain Concrete Diaphragm Wall 3: When constructing diaphragm walls near viaduct piles, low-headroom trenching machines are used to shorten trench section lengths, and high-quality mud slurry and increased mud slurry specific gravity are employed to reduce the risk of trench collapse. Locking pipe joints or milling joints can be used between the first and second phase trench sections. The specific procedures are: constructing the guide wall, drilling and excavation, mud slurry wall protection, cleaning the trench bottom, and pouring underwater concrete.
[0030] Drilled pile construction: Drilled pile construction near the viaduct piles adopts low-headroom rotary drilling piles, and measures such as configuring high-quality mud and increasing the mud specific gravity are taken to reduce the risk of hole collapse; the specific procedures are hole excavation, mud wall protection, hole cleaning at the bottom of the trench, reinforcement cage below, and underwater concrete pouring.
[0031] Excavation of the foundation pit: During the excavation process, the pit is excavated in layers, with support first and then excavation. Drilled piles serve as the main load-bearing retaining structure, while plain concrete underground continuous walls serve as the water-retaining structure, which can effectively reduce the risk of foundation pit deformation and leakage during construction.
[0032] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings and specific examples. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.
Claims
1. A foundation pit support structure with low clearance adjacent to viaduct piles, characterized in that: The structure includes a plain concrete diaphragm wall (3), internal supports (4), and multiple bored piles (2). The plain concrete diaphragm wall (3) is vertically installed on the side of the viaduct pile cap (1-2) and the viaduct pile (1-1). The bored piles (2) are spaced apart on the outside of the plain concrete diaphragm wall (3). Internal supports (4) are installed between the bored piles (2).
2. The foundation pit support structure with low clearance adjacent to viaduct piles according to claim 1, characterized in that: The plain concrete underground continuous wall (3) and the bored pile (2) are both set below the soft soil layer (5-1), and their positions do not exceed the projection line of the viaduct (1-4).
3. The foundation pit support structure with low clearance adjacent to viaduct piles according to claim 2, characterized in that: The plain concrete underground continuous wall (3) passes through the soft soil layer (5-1) and the sand layer (5-2) in sequence and is inserted into the impermeable rock layer (5-3).
4. The foundation pit support structure with low clearance adjacent to viaduct piles according to claim 3, characterized in that: The bored pile (2) passes through the soft soil layer (5-1) and inserts into the sand layer (5-2).
5. A foundation pit support structure with low clearance adjacent to viaduct piles according to any one of claims 1-4, characterized in that: The plain concrete diaphragm wall (3) is equipped with a lock joint (3-1).
6. The foundation pit support structure with low clearance adjacent to viaduct piles according to claim 5, characterized in that: The plain concrete diaphragm wall (3) is equipped with a milling joint (3-2).
7. The foundation pit support structure with low clearance adjacent to viaduct piles according to claim 1, characterized in that: The distance between the plain concrete diaphragm wall (3) and the viaduct pile cap (1-2) is not less than 1.5D, where D is the bottom diameter of the bridge pile (1-5); the distance between the plain concrete diaphragm wall (3) and the viaduct pile (1-1) is not less than 1.5D, where D is the bottom diameter of the bridge pile (1-5).
8. A foundation pit support structure with low clearance adjacent to viaduct piles according to claim 7, characterized in that: The spacing between the bored piles (2) and the plain concrete diaphragm wall (3) is 200-300mm.
9. A foundation pit support structure with low clearance adjacent to viaduct piles according to claim 8, characterized in that: The spacing between the bored piles (2) is 150-250mm.
10. A foundation pit support structure with low clearance adjacent to viaduct piles according to claim 1, characterized in that: The internal support (4) includes multiple steel supports or multiple concrete supports arranged horizontally between the bored piles (2).