Triaxial cement-soil mixing pile waterproof curtain
By using triaxial cement-soil mixing piles to form the outer ring and bottom water-stop curtain during shaft construction, the problems of high cost and long construction time of support and drainage measures in sandy soil were solved, achieving efficient project progress and safety.
Patent Information
- Application Number
- CN202422917246.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-28
- Publication Date
- 2025-10-10
- Estimated Expiration
- 2034-11-28
AI Technical Summary
Traditional shaft construction in sandy soils has high support and drainage costs, long construction times, and water leakage that seriously affects progress.
Three-axis cement-soil mixing piles are used to form the outer ring and bottom water-stop curtain, with a pile diameter of 650mm and a pile spacing of 450mm. The height of the outer ring water-stop curtain is the shaft height plus 5 to 6m, and the bottom water-stop curtain is 2 to 3m away from the shaft bottom plate. The overlap is set with an overlap length of 1.8 to 2.2m. P·O 42.5 ordinary Portland cement is used, with a water-cement ratio of 1.5-2.0 and a cement content of 15% to 20%. The drill bit stirs and sinks at 0.5m/min and rises at 0.8-1.0m/min. The grouting pressure is 0.4MPa-0.6MPa. The construction adopts a skip-slot double-hole full-set re-mixing method.
It achieves short construction time and high efficiency in sandy soil, effectively ensures project progress and safety, and has good promotion value.
Smart Images
Figure CN223423278U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the technical field of underground vertical shaft foundation pit water-stop curtain construction, in particular to a tri-axial cement-soil mixing pile water-stop curtain. Background Art
[0002] Sandy soil refers to soil with a high sand content in its soil particle composition. In engineering, soil with a particle size greater than 2mm in mass not exceeding 50% of the total mass and a particle size greater than 0.075mm in mass exceeding 50% of the total mass should be named sandy soil.
[0003] Traditional shaft construction often employs support and drainage measures such as Larsen steel sheet piles with drainage, anchor-sprayed support and drainage, and jet grouting. In sandy soils, these support and drainage measures are expensive, time-consuming, and uneconomical. Water leakage during the process can severely impact construction progress. Therefore, a water-stop curtain suitable for sandy soils and a corresponding construction method are urgently needed. Utility Model Content
[0004] The purpose of the utility model is to overcome the defects of the prior art and propose a tri-axial cement-soil mixing pile water-stop curtain.
[0005] In order to achieve the above-mentioned purpose, the utility model provides a tri-axis cement-soil mixing pile water-stop curtain for protection of shaft construction, wherein the water-stop curtain comprises: an outer ring water-stop curtain formed by a circle of tri-axis cement-soil mixing piles arranged around the shaft and at a fixed length from the edge of the shaft, and a bottom water-stop curtain formed by several tri-axis cement-soil mixing piles arranged at a fixed distance below the bottom plate of the shaft, wherein the outer ring water-stop curtain and the bottom water-stop curtain are tightly sealed.
[0006] Preferably, the pile diameters of the tri-axis cement soil mixing piles are all 650 mm, and the pile spacings are all 450 mm.
[0007] Preferably, each triaxial cement-soil mixing pile of the outer ring water-stop curtain has the same height, which is the height of the vertical shaft plus 5 to 6 meters.
[0008] Preferably, the fixed length between each tri-axial cement-soil mixing pile of the outer ring water-stop curtain and the side line of the shaft is 1.8 to 2.2 m.
[0009] Preferably, two adjacent tri-axis cement-soil mixing piles of the outer ring water-stop curtain are overlapped.
[0010] Preferably, each triaxial cement-soil mixing pile of the bottom water-stop curtain has the same height and is 2 to 3 meters away from the bottom plate of the shaft.
[0011] Preferably, the upper portion of each tri-axis cement-soil mixing pile of the bottom water-stop curtain is an empty pile without cement.
[0012] Preferably, two adjacent tri-axis cement-soil mixing piles of the bottom water-stop curtain are overlapped.
[0013] Preferably, a water level observation well is provided outside the set distance of the outer ring water-stop curtain for observing water level changes.
[0014] Compared with the prior art, the advantages of this utility model are:
[0015] The three-axis cement-soil mixing pile water-stop curtain of the utility model is suitable for sandy soil, has short construction time, high construction efficiency, simple method, effectively ensures the progress and safety of engineering construction, and has good promotion value. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 This is a longitudinal cross-sectional view of the triaxial cement-soil mixing pile water-stop curtain of Example 1 of the present utility model;
[0017] Figure 2 This is a schematic diagram of excavating the guide trench and placing the positioning steel;
[0018] Figure 3 It is a schematic diagram of the construction sequence;
[0019] Figure 4 This is a schematic diagram of the construction process.
[0020] Reference numerals
[0021] 1. Outer ring water-stop curtain 2. Bottom water-stop curtain 3. Water level observation well
[0022] 4. Retaining wall 5. Shaft wall DETAILED DESCRIPTION
[0023] The technical solution of the present utility model is described in detail below with reference to the accompanying drawings and embodiments.
[0024] Example
[0025] like Figure 1 As shown, an embodiment of the utility model provides a tri-axis cement-soil mixing pile water-stop curtain for protection of shaft construction, the water-stop curtain comprising: an outer ring water-stop curtain 1 formed by a circle of tri-axis cement-soil mixing piles arranged around the shaft and at a fixed length from the edge of the shaft, and a bottom water-stop curtain 2 formed by a number of tri-axis cement-soil mixing piles arranged at a fixed distance below the bottom plate of the shaft, the outer ring water-stop curtain 1 and the bottom water-stop curtain 2 overlap to seal the bottom.
[0026] In the figure, 3 is a water level observation well, which is used to observe water level changes, thereby achieving support and water-stopping effects. 4 is a retaining wall, and 5 is the shaft wall.
[0027] The diameter of the triaxial cement-soil mixing piles is 650mm, and the pile spacing is 450mm. The adjacent triaxial cement-soil mixing piles of the outer ring water-stop curtain 1 are overlapped. Each triaxial cement-soil mixing pile of the outer ring water-stop curtain 1 has the same height, which is the shaft height plus 5 to 6 meters. Each triaxial cement-soil mixing pile has a fixed distance of 1.8 to 2.2 meters from the shaft edge. Each triaxial cement-soil mixing pile of the bottom water-stop curtain 2 has the same height, which is 2 to 3 meters from the shaft floor. The top of each triaxial cement-soil mixing pile is hollow and does not contain cement. The adjacent triaxial cement-soil mixing piles of the bottom water-stop curtain 2 are overlapped.
[0028] In one embodiment, a circle of triaxial cement-soil mixing piles is set 1.8m from the outer edge of the shaft structure, with a height equal to the shaft height + 5m, forming the shaft's outer ring waterstop curtain 1. Inside, triaxial cement-soil mixing piles are constructed within a range of 2m from the bottom of the shaft structure floor, forming the shaft's bottom waterstop curtain 2. The triaxial cement-soil mixing piles all have a diameter of 650mm and a pile spacing of 450mm. Water level observation wells 3 are set 200mm outside the outer ring of support mixing piles to monitor water level changes, thereby achieving both support and waterstopping effects. The above data is for illustrative purposes only and is not intended to be limiting.
[0029] The specific requirements for triaxial cement mixing piles are as follows:
[0030] The cement used is P·O 42.5 ordinary Portland cement with a water-cement ratio of 1.5-2.0. The cement content is 15%-20% of the natural mass of the soil, and the content can be modified according to the stratum and specific conditions.
[0031] The drill bit's sinking speed should be controlled within 0.5 m / min, and its lifting speed within 0.8-1.0 m / min, ensuring uniform sinking and lifting. The grouting pressure should be 0.4 MPa-0.6 MPa. A double-hole, full-set, remixing construction method with a jumper and a single-hole overlap can be used, as is well known in the art. The slurry should be mixed for at least 2 minutes and used immediately after mixing.
[0032] The specific process is as follows:
[0033] 1. Process
[0034] Construction preparation → measurement and layout → excavation of guide trenches and clearing of obstacles → setting up guide frames and positioning → mixer placement and calibration → drilling, mixing and sinking (cement slurry preparation and grouting injection) → mixing and lifting or repeated mixing → pile formation → mixer relocation → mud and water treatment → cement soil pile hardening.
[0035] 2. Construction preparation
[0036] 1) Material preparation
[0037] Cement: P·O 42.5 ordinary Portland cement shall be used, and quality inspection shall be carried out on a batch basis. It can only be used after passing the test.
[0038] Water: Use fresh water that meets the requirements of the regulations.
[0039] 2) Mechanical equipment preparation: The cement mixing piles of this project are three-axis cement mixing piles, equipped with a three-axis mixing pile machine.
[0040] 3) Site Preparation: The site should be drained in advance. Use an excavator to remove all obstacles (including large rocks, tree roots, and domestic garbage) in the piling area, and then backfill with dry soil. The air compressor, cement tank, and slurry pool should be properly positioned.
[0041] 3. Measurement and layout
[0042] Site cleaning: Before construction, the site must be cleaned according to technical specifications. After cleaning, the site should be leveled, and an inspection form should be filled out. Only after the supervision engineer has signed and confirmed that the site is qualified can the next construction process be carried out.
[0043] Pile layout diagram: Before construction begins, a pile layout diagram should be drawn based on the construction design drawing. The number and coordinates of each pile should be marked on the pile layout diagram. The pile layout diagram should be submitted to the supervising engineer for acceptance and confirmation before construction can begin.
[0044] Surveying and staking out: Before construction begins, the guide points and leveling points handed over by the construction company will be reviewed with the supervising engineer for accuracy. Surveyors will survey and stake out pile positions, original ground elevations, and orifice elevations according to the construction design drawings, inserting sample rods. Surveying and staking out records and pile layout plans will be submitted to the supervising engineer for review and spot check. A surveying and staking out report will be completed and approved by the supervising engineer.
[0045] 4. Cement content and water-cement ratio
[0046] The water-cement ratio is 1.5-2.0, and the cement content is 15%-20% of the natural mass of the soil. The content can be modified according to the stratum and specific conditions.
[0047] 5. Excavate the guide ditch and place the positioning steel
[0048] According to the deformation of the foundation pit, the trench is excavated to place the positioning steel, four fixed supports are set, two steels are placed in the vertical direction and welded to the fixed supports, two steels are placed in parallel and welded to the vertical steel, and steel positioning cards are arranged on the upper side. Figure 2 .
[0049] 6. Mixer positioning calibration
[0050] Draw positioning lines on the positioning steel, conduct a technical inspection and correction of the positioning before, during and after the pile movement and positioning. The piles must be set steadily, with strict control of verticality, and the positioning deviation must be less than 2 cm.
[0051] 7. Pile construction
[0052] The construction sequence of "one hole per socket" is used to ensure the continuity of the wall and the quality of the joints, and repeated drilling is used to achieve the water-stopping effect. Figure 3 The figure shows a schematic diagram of the construction sequence. Looking down, it can be seen that two adjacent tri-axial cement-soil mixing piles are overlapped.
[0053] Construction process: drilling, mixing and sinking → repeated mixing at the bottom of the pile → mixing and lifting → completing a wall mixing, see Figure 4 .
[0054] The drilling speed should be controlled within 0.5 m / min, and the lifting speed within 0.8-1.0 m / min, ensuring uniform sinking and lifting. The grouting pressure should be 0.4 MPa-0.6 MPa. A double-hole, full-set, remixing method with a single-hole overlap can be used. The slurry should be mixed for at least 2 minutes and used immediately after mixing. The interval between adjacent piles should not exceed 12 hours.
[0055] Each triaxial cement-soil mixing pile of the bottom water-stop curtain 2 has the same height, 2 to 3 meters from the shaft bottom plate. The upper part of each triaxial cement-soil mixing pile is an empty pile without cement.
[0056] 8. Quality control and testing
[0057] The main control items are the quality of cement and admixtures, cement dosage, water-cement ratio, pile strength, and foundation bearing capacity. The general control items are mixing and lifting speed, pile bottom elevation, pile top elevation, pile position deviation, pile diameter, verticality, overlap, interval time, etc., to ensure the water-stop curtain effect.
[0058] After the waterstop curtain is constructed, the shaft is installed at the pre-determined location.
[0059] 9. Quality assurance measures
[0060] ① The construction site must be leveled in advance and must not be backfilled with miscellaneous soil or domestic waste. Before construction, the performance of the equipment and the various technical parameters of the construction process must be inspected and calibrated. The relevant technical parameters must be provided to the on-site supervision engineer in a timely manner as a basis for controlling the quality of the mixing piles.
[0061] ② Conduct process tests according to design requirements to determine various construction parameters. During construction, strictly adhere to the design and process requirements. If soil layers form around the piles, increase the mixing frequency or increase the cement content for relatively weak soil layers.
[0062] ③. The number, width, vertical angle between the blades of the mixing head and the mixing shaft, the number of rotations of the mixing head, and the lifting speed are matched with each other to ensure that the number of mixing times of the soil within the reinforcement depth range meets the specification requirements.
[0063] ④. During construction, the chassis of the pile mixing machine should always be kept horizontal and the guide frame vertical. The vertical deviation of the pile mixing machine should not exceed 1%, the deviation of the pile position should not exceed 50mm, and the pile diameter and length should meet the design requirements.
[0064] ⑤. The prepared slurry must not be segregated or stored for too long, and must be pumped continuously. The slurry pump delivery volume, the time it takes for the slurry to reach the spraying port through the slurry delivery pipe, and the drill bit lifting speed must be based on the test calibration parameters.
[0065] ⑥. Front-end operation and back-end slurry supply should be closely coordinated, and the number and speed of the front-end mixer spraying and lifting should be consistent with the calibrated construction process parameters of the test pile.
[0066] ⑦. If the backstage slurry supply is shut down, promptly notify the front desk to prevent broken piles and slurry shortages. Lower the pile mixer to 0.5m below the slurry stop point and resume slurry spraying and lifting when slurry supply is restored. Three hours after the shutdown, remove and clean the slurry delivery pipe. Ensure that the speed and number of spraying, mixing, and lifting times meet design and construction process requirements. The spraying volume and lifting speed are controlled by a flow meter and recorded by a dedicated person.
[0067] ⑧. When the top of the mixing pile approaches the design elevation, special attention should be paid to the construction quality of the pile head. An additional shotcrete mixing should be carried out within 1.0 to 1.5 meters of the pile top. At the same time, the mixing should be carried out slowly when the shotcrete mixing is lifted out of the ground from 1 meter below the ground. When the shotcrete nozzle reaches the pile top elevation, the lifting should be stopped and the mixing should be continued for 10 to 20 seconds to ensure a dense and uniform pile head.
[0068] ⑨ If the slurry delivery pipe is bent, under external pressure, or leaking, promptly inspect and straighten the pipe to eliminate the external pressure. If leaks are found, repair them. If severe, shut down the machine and replace the pipe. If the slurry delivery pipe is too long and the pressure loss is excessive, locate the slurry preparation tank as close to the pile location as possible to shorten the slurry delivery pipe. If site conditions are not met, use a booster pump to adjust the pressure.
[0069] Finally, it should be noted that the above embodiments are intended only to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art will understand that modifications or equivalent substitutions to the technical solutions of the present invention do not depart from the spirit and scope of the present invention and are intended to be encompassed by the claims of the present invention.
Claims
1. A triaxial cement soil mixing pile water-stop curtain for shaft construction protection, characterized in that: The water-stop curtain comprises: an outer ring water-stop curtain (1) formed by a circle of three-axis cement-soil mixing piles arranged around the shaft and at a fixed length from the shaft edge, and a bottom water-stop curtain (2) formed by a plurality of three-axis cement-soil mixing piles arranged at a fixed distance below the shaft bottom plate, wherein the outer ring water-stop curtain (1) and the bottom water-stop curtain (2) are overlapped and sealed.
2. The triaxial cement soil mixing pile water-stop curtain according to claim 1, characterized in that: The pile diameters of the triaxial cement-soil mixing piles are all 650 mm, and the pile spacings are all 450 mm.
3. The triaxial cement soil mixing pile water-stop curtain according to claim 1, characterized in that: Each triaxial cement-soil mixing pile of the outer ring water-stop curtain (1) has the same height, which is the height of the vertical shaft plus 5 to 6 meters.
4. The triaxial cement soil mixing pile water-stop curtain according to claim 1, characterized in that: The fixed length between each triaxial cement-soil mixing pile of the outer ring water-stop curtain (1) and the vertical shaft edge line is 1.8 to 2.2 meters.
5. The triaxial cement soil mixing pile water-stop curtain according to claim 1, characterized in that: Two adjacent triaxial cement-soil mixing piles of the outer ring water-stop curtain (1) are overlapped.
6. The triaxial cement soil mixing pile water-stop curtain according to claim 1, characterized in that: Each triaxial cement-soil mixing pile of the bottom water-stop curtain (2) has the same height and is 2 to 3 meters away from the shaft bottom plate.
7. The tri-axial cement soil mixing pile water-stop curtain according to claim 5, characterized in that: The upper part of each triaxial cement-soil mixing pile of the bottom water-stop curtain (2) is an empty pile without cement.
8. The tri-axial cement soil mixing pile water-stop curtain according to claim 5, characterized in that: Two adjacent triaxial cement-soil mixing piles of the bottom water-stop curtain (2) are overlapped.
9. The tri-axial cement soil mixing pile water-stop curtain according to claim 1, characterized in that: A water level observation well (3) is provided outside the set distance of the outer ring water-stop curtain (1) for observing water level changes.