Structure for improving joint waterstop performance of staged underground diaphragm wall

Abstract

The utility model provides a structure for improving the joint waterstop performance of a staged underground diaphragm wall, which belongs to the technical field of foundation pit engineering and comprises a first-stage underground diaphragm wall and a second-stage underground diaphragm wall, and a first-stage reinforcement cage and a second-stage reinforcement cage are respectively arranged in the first-stage underground diaphragm wall and the second-stage underground diaphragm wall; the second-stage underground diaphragm wall comprises a first part and a second part which are connected with each other, the first part comprises a horizontal connecting part and a vertical connecting part which are connected in an L shape, the second part is connected to one side of the vertical connecting part, and the two sides of the end of the first-stage underground diaphragm wall abut against the horizontal connecting part and the vertical connecting part respectively. According to the utility model, the leakage path of the cold joint is prolonged through the Z-like second-stage underground diaphragm wall 2, the connection quality of the cold joint is improved through the cast-in-situ bored pile 4, and the foundation is reinforced through the MJS grouting reinforcement pile 3, so that the water stop performance of the joint of the staged underground diaphragm wall is improved, and the purposes of improving the water stop effect of the joint and ensuring the excavation construction safety of a foundation pit are achieved.

Description

Technical Field

[0001] This utility model belongs to the field of foundation pit engineering technology, and more specifically, it relates to a structure that improves the water-stopping performance of joints in phased underground continuous walls. Background Technology

[0002] According to the "Technical Specification for Foundation Pit Support" (JGJ120-2012), foundation pit support is defined as follows: temporary retaining, reinforcement, protection, and groundwater control measures adopted for foundation pits to protect the safety of underground main structure construction and the surrounding environment. 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] Diaphragm walls are a common support structure in foundation pit engineering. Using trenching machinery and with slurry wall support, a narrow, deep trench is excavated along the perimeter of the deep excavation project. A reinforcing cage is then suspended inside the trench, and finally, underwater concrete is poured using the tremie method to form a reinforced concrete wall unit. This process is repeated segment by segment until a continuous reinforced concrete wall is formed.

[0004] In practical applications, for some pre-embedded projects, the diaphragm wall has been pre-embedded and implemented in the early stage. Later, due to the adjustment of the plan, the outline of the foundation pit has changed, and it is necessary to build a new diaphragm wall to lengthen and widen it. At this time, there is a problem of connecting the joint between the old and new diaphragm walls. The joint is the weak point of the entire foundation pit, which is prone to dangerous situations such as water inrush and sand inrush. Utility Model Content

[0005] The purpose of this utility model is to provide a structure that improves the water-stopping performance of the joints of phased underground continuous walls, thereby enhancing the water-stopping effect of the joints and ensuring the safety of foundation pit excavation.

[0006] To achieve the above objectives, this utility model provides a structure for improving the water-stopping performance of joints in phased diaphragm walls, comprising a first-phase diaphragm wall and a second-phase diaphragm wall, wherein a first-phase reinforcing cage and a second-phase reinforcing cage are respectively provided in the first-phase diaphragm wall and the second-phase diaphragm wall; the second-phase diaphragm wall comprises a first part and a second part that are connected to each other, the first part comprising a horizontal connecting part and a vertical connecting part that are connected in an L-shape, the second part being connected to one side of the vertical connecting part, and the ends of the first-phase diaphragm wall abutting against the horizontal connecting part and the vertical connecting part on both sides respectively.

[0007] Furthermore, the length of the horizontal connecting part is not less than 2m.

[0008] Furthermore, it also includes bored cast-in-place piles, which simultaneously engage with the first portion and the first-phase diaphragm wall.

[0009] Furthermore, the core of the bored pile is located at the junction of the first-phase diaphragm wall and the second-phase diaphragm wall.

[0010] Furthermore, the diameter of the bored pile is 800-1000mm.

[0011] Furthermore, the length of the bored pile is 0.5-1.5m shorter than the height of the first-phase diaphragm wall.

[0012] Furthermore, the allowable deviation of the verticality of the bored pile is ±1 / 300.

[0013] Furthermore, it also includes MJS grouting reinforcement piles, which are disposed at the end near the horizontal connection portion, and the MJS grouting reinforcement piles simultaneously engage with the first part and the first-phase diaphragm wall. The maximum engagement depth of the MJS grouting reinforcement piles with the first part is not less than 500 mm, and the maximum engagement depth of the MJS grouting reinforcement piles with the first-phase diaphragm wall is not less than 500 mm.

[0014] Furthermore, the cross-section of the MJS grouting reinforced pile is fan-shaped or semi-circular.

[0015] Furthermore, the allowable deviation of the verticality of the MJS grouting reinforced pile is ±1 / 150.

[0016] Compared with the prior art, the present invention has the following technical effects:

[0017] This utility model discloses a structure for improving the water-stopping performance of joints in phased diaphragm walls. By designing the second-phase diaphragm wall as an L-shaped first part and a second part, the overall second-phase diaphragm wall is shaped like a "Z". The ends of the first-phase diaphragm wall abut against the horizontal and vertical connection parts of the second-phase diaphragm wall, respectively. This can extend the cold joint leakage path, thereby improving the joint water-stopping effect and ensuring the safety of foundation pit excavation. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 A schematic diagram of the plan layout of a structure for improving the water-stopping performance of joints in a phased underground continuous wall, provided for an embodiment of this utility model;

[0020] Figure 2 for Figure 1 Structural schematic diagram of the diaphragm wall in Phase II.

[0021] The following are the labeling elements in the figure:

[0022] 1. Phase I diaphragm wall; 2. Phase II diaphragm wall; 3. MJS grouting reinforcement pile; 4. Drilled cast-in-place pile; 5. Phase I reinforcement cage; 6. Phase II reinforcement cage; 201. Part I; 202. Part II; 2011. Horizontal connection; 2012. Vertical connection. Detailed Implementation

[0023] To make the technical problems, technical solutions, and beneficial effects of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the present utility model.

[0024] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0025] It should be understood that the terms "length", "upper", "lower", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0026] The terminology used in the embodiments of this utility model is for the purpose of describing particular embodiments only and is not intended to be limiting of the utility model. The singular forms “a,” “the,” and “the” used in the embodiments of this utility model and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0027] The terms "first" and "second" are used for descriptive purposes only, to distinguish objects, such as substances, from one another, and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. For example, without departing from the scope of the embodiments of this utility model, a first XX can also be referred to as a second XX, and similarly, a second XX can also be referred to as a first XX. Thus, a feature defined with "first" and "second" may explicitly or implicitly include one or more of that feature.

[0028] When the excavation depth of a foundation pit is large, the geological conditions are poor, and the groundwater level is high, the treatment of the joints between the old and new diaphragm walls is particularly important. Water and sand leakage is prone to occur at the joints of phased diaphragm walls, endangering the safety of surrounding buildings and the foundation pit itself. Traditional methods such as adding surface grouting or high-pressure jet grouting piles for reinforcement have some disadvantages. Therefore, this utility model provides a structure to improve the water-stopping performance of the joints of phased diaphragm walls, ensuring the safety of foundation pit construction.

[0029] Please see Figure 1 , Figure 2 The present invention will now describe a structure for improving the water-stopping performance of joints in phased underground continuous walls.

[0030] In one embodiment of the present invention, a structure for improving the water-stopping performance of joints in phased diaphragm walls includes a first-phase diaphragm wall 1 and a second-phase diaphragm wall 2. A first-phase reinforcing cage 5 and a second-phase reinforcing cage 6 are respectively installed within the first-phase diaphragm wall 1 and the second-phase diaphragm wall 2. The second-phase diaphragm wall 2 includes a first part 201 and a second part 202 connected to each other. The first part 201 includes a horizontal connecting part 2011 and a vertical connecting part 2012 connected in an L-shape. The second part 202 is connected to one side of the vertical connecting part 2012. The ends of the first-phase diaphragm wall 1 abut against the horizontal connecting part 2011 and the vertical connecting part 2012 on both sides.

[0031] In this embodiment, the first-phase diaphragm wall 1 is a diaphragm wall that has been pre-embedded and constructed in the early stage, while the second-phase diaphragm wall 2 is a diaphragm wall constructed in the later stage by lengthening or widening the first-phase diaphragm wall 1. The second-phase diaphragm wall 2 in this embodiment includes a first part 201 and a second part 202 that are connected to each other. The first part 201 includes a horizontal connecting part 2011 and a vertical connecting part 2012 that are connected in an L-shape. The second part 202 is connected to one side of the vertical connecting part 2012. That is, the second-phase diaphragm wall 2 is generally shaped like a "Z". In this way, the joint between the first-phase diaphragm wall 1 and the second-phase diaphragm wall 2 is also shaped like a "Z", which can extend the cold joint leakage path, thereby improving the joint water-stopping effect and ensuring the safety of the foundation pit excavation construction.

[0032] Furthermore, in this embodiment, the length of the horizontal connection 2011 is not less than 2m, that is, to ensure that the length of the horizontal overlap section between the first-phase underground continuous wall 1 and the second-phase underground continuous wall 2 is not less than 2m, so as to more effectively extend the cold joint leakage path and thus better improve the joint water-stopping effect.

[0033] Furthermore, in this embodiment, the structure also includes bored piles 4, which simultaneously engage with the first part 201 of the second-phase diaphragm wall 2 and the first-phase diaphragm wall 1. By setting the bored piles 4, the quality of the cold joint connection can be further improved, and the joint waterproofing effect can be further enhanced.

[0034] Furthermore, in this embodiment, the core of the bored pile 4 is located at the junction of the first-phase diaphragm wall 1 and the second-phase diaphragm wall 2, so that the interlocking area between the bored pile 4 and the second-phase diaphragm wall 2 is the same as the interlocking area between the bored pile 4 and the first-phase diaphragm wall 1, thereby enabling the bored pile 4 to uniformly improve the quality of the cold joint connection between the first-phase diaphragm wall 1 and the second-phase diaphragm wall 2.

[0035] Furthermore, in this embodiment, the diameter of the bored pile 4 is 800-1000mm. The bored pile 4 with a suitable diameter is designed so that it can effectively improve the quality of the cold joint connection between the first-phase underground continuous wall 1 and the second-phase underground continuous wall 2 while meeting the requirements of engineering economy.

[0036] Furthermore, in this embodiment, the length of the bored pile 4 is 0.5-1.5m shorter than the height of the first-phase diaphragm wall 1, generally 1m shorter. The height of the first-phase diaphragm wall 1 is the same as the height of the second-phase diaphragm wall 2. By designing the length of the bored pile 4 to be slightly shorter than the height of the first-phase diaphragm wall 1 (or the second-phase diaphragm wall 2), it is possible to prevent sand and soil below the bottom of the wall from flowing into the borehole after drilling, thereby improving the quality of the bored pile 4.

[0037] Furthermore, in this embodiment, the allowable deviation of the verticality of the bored pile 4 is ±1 / 300, so as to ensure the quality and stability of the bored pile 4, ensure the safety of the construction project, and improve the project quality.

[0038] Furthermore, the structure of this embodiment also includes MJS grouting reinforcement piles 3 (i.e., MJS (MetroJetSystem) method piles). The MJS grouting reinforcement piles 3 are positioned near the end of the horizontal connection portion 2011, and simultaneously engage with the first part 201 of the second-phase diaphragm wall 2 and the first-phase diaphragm wall 1. The maximum engagement depth between the MJS grouting reinforcement piles 3 and the first part 201 of the second-phase diaphragm wall 2 is not less than 500 mm, and the maximum engagement depth between the MJS grouting reinforcement piles 3 and the first-phase diaphragm wall 1 is not less than 500 mm. By setting the MJS grouting reinforcement piles 3 at the end connecting the first part 201 of the first-phase diaphragm wall 1 and the first part 201 of the second-phase diaphragm wall 2, the foundation at the joint can be further reinforced, improving the joint quality and thus further enhancing the joint waterproofing effect.

[0039] Furthermore, in this embodiment, the cross-section of the MJS grouting reinforcement pile 3 is fan-shaped or semi-circular. The MJS grouting reinforcement pile 3 can also be a circular pile. Compared with a circular pile, the fan-shaped or semi-circular MJS grouting reinforcement pile 3 can save on engineering costs.

[0040] Furthermore, in this embodiment, the allowable deviation of the verticality of the MJS grouting reinforced pile 3 is ±1 / 150, so as to ensure the quality and stability of the MJS grouting reinforced pile 3, ensure the safety of the construction project, and improve the project quality.

[0041] In this embodiment, the specific construction technical parameters of the "Z"-shaped second-phase diaphragm wall 2 are as follows:

[0042] (1) The wall thickness of the second phase underground continuous wall 2 is determined according to the foundation pit calculation, and the length of the horizontal connection part 2011 of the "Z"-shaped wall is not less than 2.0m.

[0043] (2) During the drilling process, the trench section should always be filled with mud to maintain the stability of the trench wall.

[0044] (3) High-quality mud should be used for wall protection. If the trench wall collapses, backfilling should be carried out and the trench should be rebuilt.

[0045] (4) After the trench is completed, the trench depth, width, verticality and other parameters shall be tested in a timely manner. After the test is qualified, the hole cleaning work shall be carried out.

[0046] (5) The verticality deviation of the second phase underground continuous wall 2 shall not be greater than 1 / 300, the length deviation shall not be greater than 100mm, and the sediment thickness shall not be greater than 100mm.

[0047] (6) Hoist the second phase of the underground continuous wall reinforcement cage 6. The second phase of the underground continuous wall 2 is poured with C35 underwater concrete.

[0048] The specific construction technical parameters for bored pile 4 are as follows:

[0049] (1) The drilling equipment for the bored pile 4 must have the ability to remove steel bars. The drilling should be carried out by full casing full rotary drilling. It can only be carried out after the concrete of the second phase underground continuous wall 2 reaches 70% of the design strength.

[0050] (2) The diameter of the bored pile 4 is 800mm to 1000mm.

[0051] (3) The allowable deviation of the verticality of the bored pile 4 is ±1 / 300.

[0052] (4) The length of the bored pile 4 should be 1m shorter than the height of the second phase underground diaphragm wall 2 (or the first phase underground diaphragm wall 1) to prevent soil outside the diaphragm wall from entering the bored pile and to ensure that the bored pile is clean.

[0053] (5) After the hole is formed, clean up the sediment and other debris, and pour C20 micro-expansion underwater concrete.

[0054] The specific construction technical parameters of MJS grouting reinforced pile 3 are as follows:

[0055] (1) The diameter of the MJS grouting reinforcement pile 3 is 2000mm, and it adopts a 180-degree semicircle. The maximum overlap depth between it and the second phase underground continuous wall 2 and the first phase underground continuous wall 1 is not less than 500mm.

[0056] (2) The cement content of MJS grouting reinforced pile 3 should not be less than 40%.

[0057] (3) Permissible deviation of hole perpendicularity: ±1 / 150.

[0058] (4) The grouting flow rate is approximately 90-130 L / min, and the lifting speed is 2.5-4 cm / min.

[0059] (5) After the hole is formed, clean up the sediment and other debris, and pour C20 underwater concrete.

[0060] (6) After grouting is completed, core sampling is used to test the pile formation effect of MJS.

[0061] To enhance the water-stopping performance of the joints in the phased diaphragm wall, in one specific embodiment, based on the use of a "Z"-shaped second-phase diaphragm wall 2 to extend the cold joint leakage path, bored piles 4 and MJS grouting reinforcement piles 3 are simultaneously added. It is advisable to construct the bored piles 4 first, followed by the MJS grouting reinforcement piles 3. During the construction of the bored piles 4, the verticality needs to be carefully controlled, and the construction parameters should be adjusted in a timely manner if any deviation is found to exceed the standard.

[0062] This embodiment also provides a construction method for improving the water-stopping performance of joints in phased underground continuous walls, including the following steps:

[0063] 1. Construction of Phase I Diaphragm Wall 1: Phase I Diaphragm Wall 1 has been pre-embedded.

[0064] 2. Construction of the second phase of the "Z"-shaped underground continuous wall: trench excavation, mud wall protection, bottom cleaning of the trench, lowering of the second phase steel cage, and pouring of underwater concrete.

[0065] 3. Construction of bored piles: clearing obstacles and drilling holes, cleaning the bottom of the trench, and pouring micro-expansion underwater concrete.

[0066] 4. Construction of MJS grouting reinforcement pile 3: Construct pilot holes and perform jet grouting reinforcement.

[0067] This embodiment describes a structure for improving the water-stopping performance of joints in phased diaphragm walls. This structure is applicable to the treatment of joints between phased diaphragm walls in foundation pit support structures. It extends the cold joint leakage path by using a "Z"-shaped second-phase diaphragm wall 2, improves the cold joint connection quality by installing bored piles 4, and reinforces the foundation by adding MJS grouting reinforcement piles 3 outside the wall. This improves the water-stopping performance of the foundation pit sidewalls at the joints of the phased diaphragm walls during excavation, thereby achieving the goal of improving the joint water-stopping effect and ensuring the safety of foundation pit excavation.

[0068] The above embodiments only illustrate several implementation methods of this utility model, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of this utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model patent should be determined by the appended claims.

Claims

1. A structure for improving the water-tightness of a joint of a diaphragm wall, characterized by, The first-stage underground continuous wall and the second-stage underground continuous wall are provided with a first-stage reinforcement cage and a second-stage reinforcement cage respectively; the second-stage underground continuous wall comprises a first part and a second part connected with each other, the first part comprises a horizontal connecting part and a vertical connecting part connected in an L shape, and the second part is connected to one side of the vertical connecting part, and the end of the first-stage underground continuous wall abuts against the horizontal connecting part and the vertical connecting part respectively.

2. The structure for improving the water stop performance of the joint of the diaphragm wall in stages according to claim 1, characterized in that, The length of the horizontal connecting part is not less than 2 m.

3. The structure for improving the water stop performance of the joint of the diaphragm wall in stages according to claim 1, characterized in that, The bored pile is also provided, and the bored pile is engaged with the first part and the first-stage underground continuous wall simultaneously.

4. The structure for improving the water stop performance of the joint of the diaphragm wall in stages according to claim 3, characterized in that, The pile core of the bored pile is arranged at the connecting junction of the first-stage underground continuous wall and the second-stage underground continuous wall.

5. The structure for improving the water stop performance of the joint of the diaphragm wall in stages according to claim 3, characterized in that, The diameter of the bored pile is 800-1000 mm.

6. The structure for improving the water stop performance of the joint of the diaphragm wall in stages according to claim 3, characterized in that, The pile length of the bored pile is 0.5-1.5 m shorter than the height of the first-stage underground continuous wall.

7. The structure for improving the water stop performance of the joint of the diaphragm wall in stages according to claim 3, characterized in that, The allowable deviation of the verticality of the pile body of the bored pile is ±1 / 300.

8. A structure for improving the water sealing performance of a joint of a diaphragm wall, according to any one of claims 1 to 7, wherein The MJS grouting reinforced pile is also provided, and the MJS grouting reinforced pile is arranged close to the end of the horizontal connecting part and engaged with the first part and the first-stage underground continuous wall simultaneously, the maximum engagement depth of the MJS grouting reinforced pile with the first part is not less than 500 mm, and the maximum engagement depth of the MJS grouting reinforced pile with the first-stage underground continuous wall is not less than 500 mm.

9. The structure for improving the water stop performance of the joint of the diaphragm wall in stages according to claim 8, characterized in that, The cross section of the MJS grouting reinforced pile is in the shape of a sector or a semicircle.

10. The structure for improving the water stop performance of the joint of the diaphragm wall in stages according to claim 8, characterized in that, The allowable deviation of the verticality of the pile body of the MJS grouting reinforced pile is ±1 / 150.

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