Multi-combination type underground diaphragm wall joint waterstop reinforcement construction method

Abstract

The invention relates to a multi-combination type underground diaphragm wall joint water stop reinforcement construction method. Water stop devices are arranged at the two ends of a first open width and one end of a connecting width of an underground diaphragm wall; a first reinforcement cage is arranged in the first opening width, and a second reinforcement cage is arranged in each connecting width; first scutching concrete is poured, and connecting scutching concrete is poured in sequence, so that a water stop device is arranged at the joint of the formed underground diaphragm wall; after concrete pouring of the groove section of the underground diaphragm wall is completed and the strength reaches 100%, a row of continuously-closed stirring water stop piles are arranged on the outer side of a pit of the underground diaphragm wall, and concave stirring water stop piles are formed at joints; and finally, an MJS construction method water stop pile is arranged on the inner side of the concave shape away from the joint of the underground diaphragm wall. The water stopping devices are arranged in the first opening width and the connecting width of the underground diaphragm wall, an independent space is formed on the outer side of the pit of the underground diaphragm wall for water stopping, and the problem of leakage at the joint of the underground diaphragm wall can be well solved by combining the stirring water stopping piles and the MJS construction method water stopping piles.

Description

Technical Field

[0001] The present invention relates to the technical field of building construction, and particularly relates to a multi-combination type construction method for water-stop reinforcement at the joints of diaphragm walls adjacent to rail transit or important infrastructure in deep foundation pits. Background Art

[0002] A diaphragm wall is a trench excavation machine used on the ground in deep foundation pit support projects. Along the axis of the foundation pit, under the condition of slurry wall protection, a long and narrow deep trench is excavated. After the trench is cleared, a steel reinforcement cage is lifted and placed in the trench, and then underwater concrete is poured by the conduit method to form a unit trench section. This is carried out section by section to build a continuous reinforced concrete wall underground as a water cut-off, anti-seepage, load-bearing, and water-blocking structure. The construction of the diaphragm wall generally starts with the construction of the first opening section, and then the continuous sections are constructed and concrete is poured. However, at present, quality defects such as leakage are likely to occur at the joints after the construction of the diaphragm wall, forming weak links at the joints, and there may be a risk of groundwater leakage, resulting in the cracking and subsidence of the soil outside the foundation pit, affecting the safety of important facilities such as surrounding buildings, and there are major safety hazards. Summary of the Invention

[0003] In order to overcome the defects of the above-mentioned prior art, the purpose of the present invention is to provide a multi-combination type construction method for water-stop reinforcement at the joints of diaphragm walls, which has high safety, small construction disturbance, good water-stop effect, and significantly improves the water-stop effect at the joints of diaphragm walls.

[0004] A multi-combination type construction method for water-stop reinforcement at the joints of diaphragm walls comprises the following steps: Step 1: Set the first opening section and the connecting section in the diaphragm wall, set water-stop devices at both ends of the first opening section of the diaphragm wall respectively, and set a water-stop device at the end of the connecting section far from the first opening section; Step 2: Set a first steel reinforcement cage in the first opening section, and fix both ends of the first steel reinforcement cage to the water-stop devices at both ends in the first opening section respectively; then set a second steel reinforcement cage in each connecting section, a support structure is arranged at the end of the second steel reinforcement cage facing the first opening section, and the end far from the first opening section is fixedly connected to the water-stop device; Step 3: First pour the concrete of the first opening section, and then pour the concrete of the connecting sections at intervals for a certain time, so that the joints of the formed diaphragm wall trench sections contain water-stop devices. After the concrete is formed, the water-stop devices can effectively prevent groundwater from penetrating from the trench section joints to the inner side of the foundation pit; Step 4: After the concrete pouring of the diaphragm wall trench section is completed and the strength reaches 100%, arrange a row of continuous and closed mixing water-stop piles on the outside of the foundation pit. The mixing water-stop piles adopt the technology of socketing one hole. The first hole, the third hole, the fifth hole, etc. are the re-drilling positions, and so on; and form a concave mixing water-stop pile at the joint; Step 5: After the strength of the agitated water-stop pile reaches 100%, an MJS method water-stop pile is set at the concave inner space at the joint of the diaphragm wall.

[0005] Furthermore, the water-stop device includes wing plates, a web plate, and stiffening plates; wing plates perpendicular to the ground are respectively fixed on both sides of the web plate, and stiffening plates perpendicular to the ground are symmetrically arranged on the front and back of the middle of the web plate, and the whole water-stop device is in a "king" shape structure.

[0006] Furthermore, the first steel reinforcement cage includes first transverse steel bars and first vertical steel bars; the first transverse steel bars and the first vertical steel bars are spot-welded and fixed, and the outer sides of both ends of the first transverse steel bars are respectively fixed to the inner surface of the wing plate by double-sided welding to form a steel reinforcement cage structure.

[0007] Furthermore, the second steel reinforcement cage includes second transverse steel bars, inclined steel bars, vertical steel bars, third transverse steel bars, connecting steel bars, and second vertical steel bars; one end of the third transverse steel bar is fixed to one end of the vertical steel bar, and the other end of the vertical steel bar is fixed to one end of the inclined steel bar to form a support assembly; a group of support assemblies are tied and fixed by connecting steel bars arranged at the other end of the third transverse steel bar to form a support structure; the other end of the inclined steel bar of the support structure is welded and fixed to one end of the second transverse steel bar, and the outer side of the other end of the second transverse steel bar is fixed to the inner surface of the wing plate by double-sided welding to form a steel reinforcement cage structure.

[0008] Furthermore, an opening is formed between the third transverse steel bars connected by the connecting steel bars corresponding to the support structure; the stiffening plate is inserted into the opening.

[0009] Furthermore, in Step 4: The agitated water-stop pile adopts the three-axis cement-soil mixing pile process, and is positioned, agitated and sunk, grout-sprayed and agitated and lifted, repeatedly agitated and sunk, and repeatedly agitated and lifted in sequence until the construction of the agitated water-stop pile is completed. The diameter of the agitated water-stop pile is 850 mm, the spacing is 600 mm, the pile length is from the natural ground elevation to 8 m below the bottom elevation of the foundation pit, the cement content is 25%, the grout-spraying pressure is 0.8 MP, and the agitation and lifting speed is 1 m / min.

[0010] Furthermore, in Step 5: Position and center the MJS ultra-high pressure jet grouting rig and adjust the levelness. Calculate the number of drill pipe sections to be lowered according to the designed hole depth, lower the drill pipe section by section to make the nozzle position reach the designed elevation, and then start grouting. When grouting, use a high-pressure pump and high-pressure air for jetting, rotate at the original position for more than 60 seconds, and start the jet grouting step-by-step lift after the in-situ pressure reaches the designed value; stop jet grouting when the slurry nozzle is lifted to 100 mm above the designed pile top elevation, lift the drill pipe and remove it from the hole mouth section by section, clean the drill pipe, grouting pump and conveying pipeline, and then move the rig to the next hole for construction to form an MJS method water-stop pile.

[0011] Furthermore, in Step 5: The reinforcement depth of the MJS method water-stop pile is from the natural ground surface to 8 m below the foundation pit bottom elevation. The construction swing spraying direction of the MJS method water-stop pile is towards the side of the diaphragm wall, the swing spraying angle is 180 degrees, the cement admixture is 40%, the slurry spraying pressure is 40 MP, the air pressure is 0.7 MP, and the nozzle lifting speed is 5 cm / min.

[0012] In summary: By setting a water-stop device at the joints of the first opening panel and the connecting panel of the diaphragm wall, a water-stop structural measure is formed to achieve the water-stop function. Combining the mixing water-stop pile and the MJS method water-stop pile makes the soil outside the diaphragm wall more compact, forming an independent space outside the foundation pit of the diaphragm wall for water-stop, greatly avoiding the leakage risk at the weak positions of the joints, effectively solving a series of safety hazards brought by the foundation pit settlement and cracking outside the pit due to the leakage problem, and ensuring the safety of the foundation pit construction. Description of the Drawings

[0013] Fig. 1 is a schematic structural diagram of the diaphragm wall connection structure of the present invention; Fig. 2 is a schematic structural diagram of the water-stop device of the present invention; Fig. 3 is a schematic structural diagram of the connection between the first steel reinforcement cage and the water-stop device in the first opening panel of the present invention; Fig. 4 is a schematic structural diagram of the second steel reinforcement cage in the connecting panel of the present invention; Fig. 5 is a schematic construction structural diagram of the mixing water-stop pile of the present invention; Fig. 6 is a schematic construction structural diagram of the joint method water-stop pile of the present invention.

[0014] Wherein: water-stop device 1; first steel reinforcement cage 2; second steel reinforcement cage 3; wing plate 11; web plate 12; reinforcement plate 13; first transverse steel bar 21; first vertical steel bar 22; second transverse steel bar 31; inclined steel bar 32; vertical steel bar 33; third transverse steel bar 34; connecting steel bar 35; second vertical steel bar 36; opening 37. Detailed Embodiments

[0015] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments.

[0016] As Figures 1 to 6 shown, a multi-combination type diaphragm wall joint water-stop reinforcement construction method comprises the following steps: Step 1: Set the first opening panel and the connecting panel for the diaphragm wall, and respectively set the water-stop device 1 at both ends of the first opening panel of the diaphragm wall, and set the water-stop device 1 at the end of the connecting panel far from the first opening panel; Step 2: Set the first steel reinforcement cage 2 in the first opening section. The two ends of the first steel reinforcement cage 2 are respectively double-sided welded and fixed to the water stop devices 1 at both ends in the first opening section. Then, set the second steel reinforcement cage 3 in each connecting section. A support structure is provided at one end of the second steel reinforcement cage 3 facing the first opening section, and the other end away from the first opening section is double-sided welded and fixed to the water stop device 1. Step 3: First, pour the concrete in the first opening section, and then pour the concrete in the connecting sections at intervals for a certain time, so that the formed diaphragm wall groove joint contains the water stop device 1. After the concrete is formed, the water stop device 1 can effectively prevent groundwater from seeping into the inner side of the foundation pit from the joint. The width dimension of the water stop device 1 is the thickness of the diaphragm wall minus 120 mm. The depth of the water stop device 1 is the same as the depth of the diaphragm wall. Step 4: After the concrete pouring of the diaphragm wall groove section is completed and the strength reaches 100%, arrange a row of continuous and closed mixing water stop piles on the outside of the foundation pit. The mixing water stop piles adopt the socketed one-hole process. The first hole, the third hole, the fifth hole, etc. are the re-drilling positions, and so on. And form a concave mixing water stop pile at the joint. Step 5: After the strength of the mixing water stop piles reaches 100%, set the MJS method water stop piles in the concave inner space at the joint of the diaphragm wall. By setting the water stop device 1 in the first opening section and the connecting sections of the diaphragm wall, the present invention forms a water stop structural measure to achieve the water stop function. Then, combined with the mixing water stop piles and the MJS method water stop piles, the soil outside the diaphragm wall is made more compact, and an independent space is formed outside the diaphragm wall foundation pit for water stop, greatly avoiding the leakage risk at the weak position of the joint, effectively solving a series of safety hazards such as the settlement and cracking of the foundation outside the pit caused by the leakage problem, and ensuring the safety of the foundation pit construction.

[0017] As a preferred embodiment, as Figure 2 shown, the water stop device 1 includes a wing plate 11, a web plate 12 and a stiffening plate 13. The wing plates 11 perpendicular to the ground are respectively fixed on both sides of the web plate 12. The stiffening plates 13 perpendicular to the ground are symmetrically arranged on the front and back of the middle of the web plate 12. The water stop device 1 is in an overall "king" - shaped structure. The lower bottom surface of the water stop device 1 is welded to the horizontal bars of the diaphragm wall, and the height is the same as the depth of the diaphragm wall. After the concrete of the diaphragm wall is formed, it can effectively prevent groundwater from seeping into the inner side of the foundation pit from the joint.

[0018] As a preferred embodiment, as Figure 1 and Figure 3 shown, the first steel reinforcement cage 2 includes first transverse bars 21 and first vertical bars 22. The first transverse bars 21 and the first vertical bars 22 are spot - welded and fixed, and the outer sides of both ends of the first transverse bars 21 are respectively double - sided welded and fixed to the inner surface of the wing plate 11 to form a steel reinforcement cage structure.

[0019] As a preferred embodiment, as Figure 1 and Figure 4 shown, the second steel cage 3 includes second transverse steel bars 31, inclined steel bars 32, vertical steel bars 33, third transverse steel bars 34, connecting steel bars 35 and second vertical steel bars 36; one end of the third transverse steel bar 34 is fixed to one end of the vertical steel bar 33, and the other end of the vertical steel bar 33 is fixed to one end of the inclined steel bar 32 to form a support assembly; a group of support assemblies are tied and fixed through the connecting steel bars 35 arranged at the other end of the third transverse steel bar 34 to form a support structure. During concrete pouring, the support structure provides support for the second transverse steel bar 31 to ensure the stability of pouring; the other end of the inclined steel bar 32 of the support structure is welded and fixed to one end of the second transverse steel bar 31, and the outer side of the other end of the second transverse steel bar 31 is fixed to the inner surface of the wing plate 11 by double-sided welding to form a steel cage structure. Double-sided welding ensures the weld quality, enables each section of the first opening and the connecting opening to cooperate with the water stop device 1 to form independent waterproof structures for water stop, and also provides guarantee for preventing leakage at the joints of the diaphragm wall.

[0020] As a preferred embodiment, as Figure 4 shown, an opening 37 is formed between the two third transverse steel bars 34 connected by the connecting steel bar 35 corresponding to the support structure; the reinforcing plate 13 is inserted into the opening 37, and this structure can better facilitate the insertion of the reinforcing plate 13 during construction, improving the stability of the overall structure pouring and the effect of preventing leakage at the joints.

[0021] As a preferred embodiment, as Figure 5 shown, in step four: the mixing cut-off wall is constructed by using the three-axis cement-soil mixing pile process, and the operations of positioning, mixing and sinking, grouting and mixing rising, repeated mixing and sinking, and repeated mixing rising are carried out in sequence until the construction of the mixing cut-off wall is completed. The diameter of the mixing cut-off wall is 850 mm, the spacing is 600 mm, the pile length is from the natural ground elevation to 8 m below the bottom elevation of the foundation pit, the cement content is 25%, the grouting pressure is 0.8 MP, and the mixing and lifting speed is 1 m / min. Through the construction of the three-axis cement-soil mixing pile, the formed mixing cut-off wall ensures the requirements of pile body strength and diameter, significantly improves the core indexes such as the strength and bearing capacity of the soil mass, and thus improves the anti-seepage and water-stop effect.

[0022] As a preferred embodiment, as Figure 6As shown, in the fifth step: Position and align the MJS ultra-high pressure jet grouting rig and adjust the levelness. Calculate the number of drill pipe joints to be lowered according to the designed hole depth, and lower the drill pipe section by section until the nozzle position reaches the designed elevation. Then start grouting. When grouting, use a high-pressure pump and high-pressure air for jetting, rotate at the original position for more than 60 seconds. After the in-situ pressure reaches the designed value, start the jet grouting step and lift. Stop jet grouting when the slurry nozzle is lifted 100 mm above the designed pile top elevation. Lift the drill pipe and remove it from the hole mouth section by section. Clean the drill pipe, grouting pump, and conveying pipeline. Then move the rig to the next hole for construction to form a MJS method waterproofing pile. Through the vertical 180-degree swing jet grouting reinforcement of the MJS method waterproofing pile, combined with the setting of the waterproof device 1 and the mixing waterproofing pile, the best waterproof effect is achieved; moreover, during the construction of the MJS method waterproofing pile, the impact on the surrounding environment and foundation disturbance is minimal, which is conducive to better protecting the rail transit on one side adjacent to the foundation pit.

[0023] As a preferred embodiment, in the fifth step: The reinforcement depth of the MJS method waterproofing pile is from the natural ground surface to 8 m below the foundation pit bottom elevation. The construction swing jet direction of the MJS method waterproofing pile is towards the diaphragm wall side, the swing jet angle is 180 degrees, the cement content is 40%, the grouting pressure is 40 MP, the air pressure is 0.7 MP, and the nozzle lifting speed is 5 cm / min. These construction parameters ensure the best waterproof effect at the joint.

[0024] Although the specific implementation manners of the present invention have been described and explained in detail above, it should be pointed out that: We can make various equivalent changes and modifications to the above implementation manners according to the concept of the present invention. As long as the resulting functional effects do not exceed the spirit covered by the specification, they should all be within the protection scope of the present invention.

Claims

1. A multi-combination underground continuous wall joint water-stopping reinforcement construction method, characterized in that: The steps are as follows: Step 1: Set the first opening panel and the connecting panel for the diaphragm wall.止水装置,在连接幅远离首开幅的一端设置止水装置; Step 2: Set the first steel cage in the first opening panel. The two ends of the first steel cage are fixedly connected to the water stop devices at the two ends in the first opening panel respectively. Then set the second steel cage in each connecting panel. A support structure is provided at one end of the second steel cage facing the first opening panel, and the other end away from the first opening panel is fixedly connected to the water stop device. Step 3: First pour the concrete in the first opening panel, and then pour the concrete in the connecting panels at intervals of a certain time, so that the water stop device is included at the joint of the formed diaphragm wall segments. After the concrete is formed, the water stop device can effectively prevent groundwater from penetrating from the joint of the segments to the inner side of the foundation pit. Step 4: After the concrete pouring of the diaphragm wall segments is completed and the strength reaches 100%, arrange a row of continuous and closed mixing water stop piles on the outside of the foundation pit. The mixing water stop piles adopt the technology of socketing one hole. The first hole, the third hole, the fifth hole, etc. are the re-drilling positions, and so on; and form a concave mixing water stop pile at the joint. Step 5: After the strength of the mixing water stop pile reaches 100%, set the MJS method water stop pile in the concave inner space at the joint of the diaphragm wall.

2. A multi-combination underground continuous wall joint water-stopping reinforcement construction method according to claim 1, characterized in that: The water stop device includes wing plates, webs and stiffening plates; the wing plates perpendicular to the ground are respectively fixed on both sides of the web, and the stiffening plates perpendicular to the ground are symmetrically arranged on the front and back of the middle of the web. The whole water stop device is in the shape of a "king" character structure.

3. A multi-combination underground continuous wall joint water-stopping reinforcement construction method according to claim 2, characterized in that: The first steel cage includes first horizontal steel bars and first vertical steel bars; the first horizontal steel bars and the first vertical steel bars are spot welded and fixed, and the outer sides of both ends of the first horizontal steel bars are fixedly connected to the inner surface of the wing plate by double-sided welding to form a steel cage structure.

4. A multi-combination underground continuous wall joint water-stopping reinforcement construction method according to claim 2, characterized in that: The second steel cage includes second horizontal steel bars, inclined steel bars, vertical steel bars, third horizontal steel bars, connecting steel bars and second vertical steel bars; one end of the third horizontal steel bar is fixed to one end of the vertical steel bar, and the other end of the vertical steel bar is fixed to one end of the inclined steel bar to form a support assembly; a group of support assemblies are tied and fixed by the connecting steel bars arranged at the other end of the third horizontal steel bar to form a support structure; the other end of the inclined steel bar of the support structure is welded and fixed to one end of the second horizontal steel bar, and the outer side of the other end of the second horizontal steel bar is fixedly connected to the inner surface of the wing plate by double-sided welding to form a steel cage structure.

5. A multi-combination underground continuous wall joint water-stopping reinforcement construction method according to claim 4, characterized in that: An opening is formed between the two third horizontal steel bars connected by the connecting steel bars corresponding to the support structure; the stiffening plate is inserted into the opening.

6. A multi-combination underground continuous wall joint water-stopping reinforcement construction method according to claim 1, characterized in that: In Step 4: The mixing water stop pile adopts the technology of three-axis cement-soil mixing pile. Positioning, mixing and sinking, spraying and mixing rising, repeated mixing and sinking, repeated mixing and rising are carried out in sequence until the construction of the mixing water stop pile is completed. The diameter of the mixing water stop pile is 850mm, the spacing is 600mm, the pile length is from the natural ground elevation to 8m below the bottom elevation of the foundation pit, the cement content is 25%, the spraying pressure is 0.8MP, and the mixing and lifting speed is 1m / min.

7. A multi-combination underground continuous wall joint water-stopping reinforcement construction method according to claim 1, characterized in that: In the step 5, the MJS ultra-high pressure rotary jet drilling rig is positioned, centered and adjusted to be horizontal, the number of sections of the drill rod to be lowered is calculated according to the designed hole depth, the drill rod is lowered section by section so that the nozzle position is at the designed elevation, and then grouting is started. A high-pressure pump and high-pressure air are used for spraying, and the grouting is rotated at the original position for more than 60 seconds. After the ground pressure reaches the designed value, the rotary jetting step is started; the rotary jetting is stopped when the slurry nozzle is lifted to 100 mm above the designed pile top elevation, the drill rod is lifted and the hole outlet is removed section by section, the drill rod, grouting pump and delivery pipeline are cleaned, and then the drilling rig is moved to the next hole for construction to form an MJS method reinforced water-stop pile.

8. A multi-combination underground continuous wall joint water-stopping reinforcement construction method according to claim 7, characterized in that: In the step five: the reinforcement depth of the MJS method water-stop piles is 8m below the natural ground to the bottom elevation of the foundation pit, the swing spraying direction of the MJS method water-stop piles is toward the underground continuous wall, the swing spraying angle is 180 degrees, the cement content is 40%, the spraying pressure is 40MP, the air pressure is 0.7MP, and the nozzle lifting speed is 5cm / min.

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