A high-pressure jet grouting and reinforced concrete pile combined water stop curtain and construction method

Abstract

The application relates to the field of building construction, in particular to a water-stopping curtain combined with high-pressure rotary jet grouting and reinforced concrete piles and a construction method, and relates to a water-stopping curtain combined with high-pressure rotary jet grouting and reinforced concrete piles, which comprises a plurality of supporting piles and a plurality of first plain concrete piles; the supporting piles are arranged along the outer edge of a foundation pit wall and are used for bearing lateral geotechnical pressure of the foundation pit; the first plain concrete piles are arranged on the side, away from the foundation pit, of the supporting piles; the first plain concrete piles are mutually engaged to form a curtain structure for blocking water in the geotechnical body outside the foundation pit from seeping into the foundation pit. The first plain concrete piles are arranged on the side, away from the foundation pit, of the supporting piles and are mutually engaged to form a curtain structure, so that there is enough construction space for the first plain concrete piles during construction, the construction quality of the first plain concrete piles can be better controlled, and the formed curtain structure of the first plain concrete piles has higher forming quality and can better block water in the geotechnical body outside the foundation pit from seeping into the foundation pit.

Description

Technical Field

[0001] This invention relates to the field of building construction, and in particular to a water-stop curtain combining high-pressure jet grouting and reinforced concrete piles, and its construction method. Background Technology

[0002] In deep foundation pit engineering, vertical water-stop curtains are installed on the outer edge of the pit wall to prevent the permeable layer outside the pit from seeping into the pit due to the difference in elevation between the inside and outside of the pit.

[0003] Interlocking piles are a type of water-stop curtain. The piles are arranged with alternating rows of unreinforced plain concrete piles (Pile A) and reinforced concrete piles (Pile B). During construction, Piles A are constructed first, followed by Piles B, with Piles B completed after the initial setting of Piles A but before its final setting. Piles B are constructed using a full-casing drilling rig, cutting away the concrete at the intersection of adjacent Piles A to achieve the interlocking effect. This design effectively stops water in addition to retaining soil.

[0004] However, with this type of water-stop curtain, the reinforced concrete piles need to be constructed between two plain concrete piles. The construction space is tight, and the construction quality is difficult to control. In the longitudinal depth range, the reinforced concrete piles and plain concrete piles often cannot achieve a precise interlocking effect, resulting in poor water-stopping effect.

[0005] Therefore, there is an urgent need for a water-stop curtain structure to solve the above-mentioned problems in the existing technology. Summary of the Invention

[0006] The purpose of this invention is to address the problems existing in the prior art of interlocking pile structure water-stop curtains, where reinforced concrete piles need to be constructed between two plain concrete piles, resulting in a compact construction space, difficulty in controlling construction quality, and the inability to achieve a precise interlocking effect between the reinforced concrete piles and plain concrete piles within the longitudinal depth range, leading to poor water-stopping effect. This invention provides a water-stop curtain combining high-pressure jet grouting piles and reinforced concrete piles, along with a construction method.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A water-stop curtain combining high-pressure jet grouting piles and reinforced concrete piles includes several support piles and several first plain concrete piles. The support piles are arranged along the outer edge of the pit wall and are used to bear the lateral rock and soil pressure of the pit. The first plain concrete piles are arranged on the side of the support piles away from the pit. The several first plain concrete piles interlock to form a curtain structure to prevent water in the rock and soil outside the pit from seeping into the pit.

[0009] Preferably, the interlocking joints between the first plain concrete piles correspond to the pile bodies of the support piles.

[0010] Preferably, the first plain concrete pile is inclined, with the root side of the first plain concrete pile close to the support pile and the head side of the first plain concrete pile away from the support pile.

[0011] Preferably, one side of the root of the first plain concrete pile is in contact with the support pile.

[0012] Preferably, the bottom elevation of the first plain concrete pile is lower than the bottom elevation of the support pile.

[0013] Preferably, the first plain concrete pile body is provided with a plurality of enlarged sections at intervals, the diameter of the enlarged sections being larger than the diameter of the plain concrete pile body.

[0014] Preferably, the portion of the first plain concrete pile located below the bottom elevation of the support pile is designated as the enlarged section.

[0015] Preferably, a second plain concrete pile is also provided between the plurality of support piles, and the second plain concrete pile and the support pile interlock with each other.

[0016] Preferably, the diameter of the second plain concrete pile is smaller than the diameter of the support pile.

[0017] Preferably, the area of ​​engagement between the second plain concrete pile and the support pile is greater than or equal to 1 / 2 of its own cross-sectional area.

[0018] A method for constructing a water-stop curtain combining high-pressure jet grouting and reinforced concrete piles includes the following steps:

[0019] Step A, Construction of the second plain concrete pile: Construct the second plain concrete pile along the edge of the pit wall to form a row of piles arranged at intervals;

[0020] Step B, Construction of support piles: Support piles are constructed between adjacent second plain concrete piles to form an interlocking structure between the support piles and the second plain concrete piles.

[0021] Step C, Construction of the first plain concrete pile: The first plain concrete pile is constructed on the side away from the foundation pit from the second plain concrete pile and the support pile, so that the first plain concrete piles form an interlocking curtain structure.

[0022] Preferably, the support piles are constructed using rotary drilling and grouting technology, while the first plain concrete pile and the second plain concrete pile are constructed using high-pressure jet grouting technology.

[0023] Preferably, the second plain concrete pile is constructed using ultra-slow-setting concrete, and the support pile is constructed before the initial setting of the second plain concrete pile.

[0024] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0025] 1. The water-stop curtain combining high-pressure jet grouting piles and reinforced concrete piles of the present invention is provided with a plurality of first concrete piles interlocking with each other to form a curtain structure on the side of the support piles away from the foundation pit. This ensures that there is sufficient construction space during the construction of the first concrete piles, so that the construction quality of the first concrete piles can be better controlled. As a result, the forming quality of the curtain structure formed by the first plain concrete piles is higher, which can better prevent water in the rock and soil outside the foundation pit from seeping into the foundation pit.

[0026] 2. The water-stop curtain combining high-pressure jet grouting piles and reinforced concrete piles of the present invention features a first plain concrete pile with its shaft inclined, the root side of which is close to the supporting pile, and the head side of which is away from the supporting pile. The inclined first plain concrete pile acts as a "guide plate," causing the soil and rock to slide downwards along it. This guides a portion of the horizontal lateral pressure from the soil and rock to act downwards along the first plain concrete pile, further preventing the transmission of this lateral pressure to the supporting pile and improving its ultimate bearing capacity. Furthermore, the downward movement of some horizontal lateral pressure along the first plain concrete pile effectively relieves some of the load directly acting on it, reducing the risk of deformation and damage and further improving the stability of the water-stop curtain structure of the present invention. At the same time, the tendency of the soil and rock to slide downward along the first plain concrete pile can also increase the density of the soil and rock on the root side of the first plain concrete pile, preventing water from seeping into the soil between the first plain concrete pile and the support pile, and further improving the water-stopping effect of the curtain structure of the present invention.

[0027] 3. In the water-stop curtain combining high-pressure jet grouting piles and reinforced concrete piles described in this invention, the portion of the first plain concrete pile located below the bottom elevation of the support pile is designated as the enlarged section. With this structural arrangement, the enlarged section at the bottom of the first plain concrete pile can interlock with the bottom of the support pile to form an integral structure, thereby achieving a better sealing effect between the bottom of the first plain concrete pile and the support pile, further improving the water-stopping effect of the curtain structure of this invention. Furthermore, in this embodiment, the first plain concrete pile also acts as a "tension bar," optimizing the stress on the support pile and reducing the risk of the support pile tipping into the pit after excavation. Attached Figure Description

[0028] Figure 1This is a structural schematic diagram of the first embodiment of a water-stop curtain combining high-pressure jet grouting piles and reinforced concrete piles;

[0029] Figure 2 This is a cross-sectional structural schematic diagram of the first embodiment of a water-stop curtain combining high-pressure jet grouting piles and reinforced concrete piles.

[0030] Figure 3 yes Figure 2 A schematic diagram of the structure of A in the middle;

[0031] Figure 4 This is a structural schematic diagram of a second embodiment of a water-stop curtain combining high-pressure jet grouting piles and reinforced concrete piles;

[0032] Figure 5 This is a schematic diagram of the construction process for a water-stop curtain construction method that combines high-pressure jet grouting with reinforced concrete piles.

[0033] Figure 6 This is a schematic diagram of the construction process for the interlocking of the support piles and the second plain concrete piles.

[0034] Markings in the diagram: 1-Support pile, 2-First plain concrete pile, 3-Expanded section, 4-Second plain concrete pile, 5-Prestressed anchor cable. Detailed Implementation

[0035] The present invention will now be described in detail with reference to the accompanying drawings.

[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the invention 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 and not intended to limit the invention.

[0037] Example 1

[0038] like Figures 1 to 3 As shown, the water-stop curtain combining high-pressure jet grouting piles and reinforced concrete piles of the present invention includes a plurality of support piles 1 and a plurality of first plain concrete piles 2. The plurality of support piles 1 are arranged along the outer edge of the pit wall and are used to bear the lateral rock and soil pressure of the pit. The first plain concrete piles 2 are arranged on the side of the support piles 1 away from the pit. The plurality of first plain concrete piles 2 interlock with each other to form a curtain structure, which is used to block the seepage of water in the rock and soil outside the pit into the pit.

[0039] The water-stopping curtain combining high-pressure jet grouting piles and reinforced concrete piles as described in this invention is formed by interlocking several first concrete piles on the side of the support pile 1 away from the foundation pit to form a curtain structure. This ensures sufficient construction space during the construction of the first concrete piles, allowing for better control of the construction quality of the first concrete piles. Consequently, the curtain structure formed by the first plain concrete piles 2 has higher forming quality and can better prevent water from seeping into the foundation pit from the soil and rock outside the foundation pit.

[0040] As a preferred embodiment, based on the above method, the interlocking joints between the first plain concrete piles 2 correspond to the pile body of the support pile 1.

[0041] Specifically, in this embodiment, the curtain structure formed by the first plain concrete piles 2, in addition to preventing water from seeping into the foundation pit from the soil and rock outside the pit, can also bear the lateral soil and rock pressure of the foundation pit together with the support piles 1. This can lead to the problem that the interlocking parts of the first plain concrete piles 2 are prone to deformation and cracking under the action of soil and rock pressure. Based on this, in this embodiment, the interlocking joints between the first plain concrete piles 2 are set to correspond to the pile bodies of the support piles 1, and the support piles 1 are used to support the interlocking parts of the first plain concrete piles 2, reducing the risk of cracking of the interlocking parts of the first plain concrete piles 2 under the action of soil and rock pressure, thereby improving the stability of the curtain structure for water stopping of the present invention.

[0042] As a preferred embodiment, based on the above method, the first plain concrete pile 2 is further inclined, and the root side of the first plain concrete pile 2 is close to the support pile 1, while the head side of the first plain concrete pile 2 is far away from the support pile 1.

[0043] Specifically, in this embodiment, the first plain concrete pile 2 is inclined. Compared to a vertically inclined configuration, the first plain concrete pile 2 is more firmly anchored in the soil and rock, preventing the lateral pressure of the soil and rock from being transmitted to the support pile 1, thus improving the ultimate bearing capacity of the support pile 1. Furthermore, the inclined configuration of the first plain concrete pile 2 acts as a "guide plate," causing the soil and rock to slide downwards along the first plain concrete pile 2. This guides a portion of the horizontal lateral pressure of the soil and rock to act downwards along the first plain concrete pile 2, further preventing the lateral pressure of the soil and rock from being transmitted to the support pile 1, and improving the ultimate bearing capacity of the support pile 1. Moreover, the downward action of a portion of the horizontal lateral pressure of the soil and rock along the first plain concrete pile 2 also effectively relieves some of the load directly acting on the first plain concrete pile 2, reducing the risk of deformation and damage to the first plain concrete pile 2, and further improving the stability of the curtain structure waterstop of this invention. At the same time, the tendency of the soil and rock to slide downwards along the first plain concrete pile 2 can also increase the density of the soil and rock on one side of the root of the first plain concrete pile 2, preventing water from seeping into the soil between the first plain concrete pile 2 and the support pile 1, and further improving the water-stopping effect of the curtain structure of the present invention.

[0044] On another front, in this invention, after the foundation pit is excavated, prestressed anchor cables 5 need to be installed in the soil and rock of the pit sidewall to improve the stress on the support piles 1. Furthermore, the prestressed anchor cables are typically inclined and anchored into the soil layer to ensure anchoring stability. In this embodiment, the inclined first plain concrete pile 2 can form a vertical fit with the prestressed anchor cable 5, improving the stability of the anchoring structure at the end of the prestressed anchor cable 5; and the vertical fit between the first plain concrete pile 2 and the prestressed anchor cable 5 allows the force applied by the prestressed anchor cable 5 to the first plain concrete pile 2 to be more even, reducing the risk of structural damage to the first plain concrete pile 2.

[0045] As a preferred embodiment, based on the above method, the root side of the first plain concrete pile 2 is further fitted with the support pile 1. This structural arrangement seals the bottoms of the first plain concrete pile 2 and the support pile 1, preventing moisture from seeping into the soil layer between them, especially preventing the infiltration of pressurized water, thereby further improving the water-stopping effect of the curtain structure of the present invention.

[0046] As a preferred embodiment, based on the above method, the bottom elevation of the first plain concrete pile 2 is further lower than the bottom elevation of the support pile 1. This structural arrangement allows for better contact between the root side of the first plain concrete pile 2 and the support pile 1, resulting in a better sealing effect between the bottoms of the first plain concrete pile 2 and the support pile 1, thereby further improving the water-stopping effect of the curtain structure of the present invention.

[0047] Example 2

[0048] like Figures 1 to 3 As shown, the water-stop curtain combining high-pressure jet grouting piles and reinforced concrete piles of the present invention, based on the above method, further includes a plurality of enlarged sections 3 spaced apart on the first plain concrete pile 2, wherein the diameter of the enlarged sections 3 is larger than the diameter of the plain concrete pile body.

[0049] In this embodiment, the enlarged section 3 enhances the structural strength of the first plain concrete pile 2. Furthermore, in another embodiment, a prestressed anchor cable 5 can be inserted into the soil layer corresponding to the enlarged section 3. This further reduces the risk of structural damage to the first plain concrete pile 2 when the prestressed anchor cable 5 is applied.

[0050] As a preferred embodiment, based on the above method, the part of the first plain concrete pile 2 located below the bottom elevation of the support pile 1 is further configured as the enlarged section 3.

[0051] With this structural design, the enlarged section 3 at the bottom of the first plain concrete pile 2 can interlock with the bottom of the support pile 1 to form an integral structure. This results in a better sealing effect between the bottom of the first plain concrete pile 2 and the support pile 1, further improving the water-stopping effect of the curtain structure of the present invention. Furthermore, in this embodiment, the first plain concrete pile 2 can also act as a "tie rod," optimizing the stress on the support pile 1 and reducing the risk of the support pile 1 tilting into the pit after excavation.

[0052] Example 3

[0053] like Figure 2 and Figure 4 As shown, the water-stop curtain combining high-pressure jet grouting piles and reinforced concrete piles of the present invention, based on the above method, further includes a second plain concrete pile 4 between several of the support piles 1, and the second plain concrete pile 4 and the support pile 1 are interlocked with each other.

[0054] In this embodiment, the support pile 1 and the second plain concrete pile 4 work together to form a second water-stopping curtain, further improving the water-stopping effect of the curtain structure of the present invention. Furthermore, the second plain concrete pile 4 can also work with the support pile 1 to jointly bear the lateral pressure of the soil and rock.

[0055] As a preferred embodiment, based on the above method, the diameter of the second plain concrete pile 4 is further smaller than the diameter of the support pile 1. This structural arrangement saves construction materials and reduces construction costs.

[0056] As a preferred embodiment, based on the above method, the area of ​​engagement between the second plain concrete pile 4 and the support pile 1 is greater than or equal to half of its own cross-sectional area. This structural arrangement ensures the engagement accuracy between the second plain concrete pile 4 and the support pile 1 within the longitudinal depth range, improving the quality of the curtain structure formed by the second plain concrete pile 4 and the support pile 1.

[0057] Example 4

[0058] like Figures 1 to 6 As shown, the construction method of a water-stop curtain combining high-pressure jet grouting and reinforced concrete piles according to the present invention includes the following steps:

[0059] Step A, Construction of the second plain concrete pile 4: Construct the second plain concrete pile 4 along the edge of the pit wall to form a row of piles arranged at intervals;

[0060] Step B, Construction of support pile 1: Support pile 1 is constructed between adjacent second plain concrete piles 4 to form an interlocking structure between support pile 1 and second plain concrete pile 4.

[0061] Step C, Construction of the first plain concrete pile 2: The first plain concrete pile 2 is constructed on the side away from the foundation pit from the second plain concrete pile 4 and the support pile 1, so that the first plain concrete pile 2 forms an interlocking curtain structure.

[0062] Specifically, in this embodiment, the second plain concrete pile 4 uses C20 underwater ultra-slow-setting plain concrete with an initial setting time ≥60h and a slump not exceeding 180mm; the support pile 1 uses underwater C30 commercial concrete with a slump of 18cm~22cm. During the construction of the support pile 1, a casing drilling rig is used to cut the plain concrete overlapping with the second plain concrete pile 4, so that the support pile 1 is embedded in the second plain concrete pile 4. The support pile 1 should be cut into a hole before the second plain concrete pile 4 has initially set; the positioning error of the second plain concrete and the support pile 1 is <10mm, and the verticality deviation of the pile is <3‰.

[0063] In order to ensure that the second plain concrete pile 4 and the support pile 1 have sufficient engagement at the bottom of the pile, the positioning error of the borehole should be strictly controlled. The allowable value of the borehole positioning error can be selected according to the following table.

[0064] Interlocking thickness / pile length less than 10m 10~15m More than 15m 100mm ±10mm ±10mm ±10mm 150mm ±15mm ±10mm ±10mm 200mm and above ±20mm ±15mm ±10mm

[0065] To ensure sufficient interlocking thickness at the bottom of the second plain concrete pile 4 and the support pile 1, in addition to strictly controlling the positioning error of the borehole opening, their verticality must also be strictly controlled. Specifically, the following steps are included:

[0066] (1) Straightness inspection and correction of the casing

[0067] Before the construction of the support pile 1, the straightness of the casing is checked and corrected on a flat ground. The straightness deviation of the casing is controlled within 1% to 2%.

[0068] (2) Monitoring and inspection of pile verticality during the drilling process

[0069] Ground monitoring: Use a plumb bob to monitor the verticality of the casing above ground at two mutually perpendicular directions, and correct any deviations immediately. This monitoring should be carried out continuously throughout the drilling process of each pile without interruption.

[0070] Hole inspection: After each section of the casing is pressed and before installing the next section, the hole must be stopped and the verticality of the casing inside the hole must be checked with a "measuring ring" or "plumb bob". If it is not up to standard, it must be corrected until it is up to standard before the next section of casing can be installed.

[0071] The setting time of the second plain concrete pile 4 should be determined based on the pile formation time of a single pile, which is directly related to geological conditions, pile length, pile diameter, and drilling rig capacity. Therefore, the setting time of the second plain concrete pile 4 is determined according to the following method:

[0072] The setting time of the second plain concrete pile 4 can be calculated according to the following formula:

[0073] T = 3t + K;

[0074] Where: T -- the setting time (initial setting time) of the second plain concrete pile 4;

[0075] K -- Storage time, generally taken as 1.0t;

[0076] t -- Time required for a single pile to be completed;

[0077] As a preferred embodiment, based on the above method, the support pile 1 is constructed using rotary drilling and grouting technology, and the first plain concrete pile 2 and the second plain concrete pile 4 are constructed using high-pressure jet grouting technology.

[0078] Specifically, the construction of the first plain concrete pile 2 and the second plain concrete pile 4 is as follows:

[0079] The first plain concrete pile 2 and the second plain concrete pile 4 were constructed using a triple-tube high-pressure jet grouting MDL-150D geological drilling rig for pilot drilling and an XL-50 type jet grouting drilling rig for operation.

[0080] The design employs geological drilling at the pile cap beam location for pilot hole preparation, with a borehole diameter of 110mm. The high-pressure jet grouting piles have a diameter of 1000mm. Before construction, test piles should be conducted to determine their suitability under the geological conditions. Technical parameters are as follows:

[0081] (1) Drill bit type: Based on the geological characteristics of the strata, use a rotary jet drill bit with a double nozzle.

[0082] (2) The cement type is PO 42.5, and the cement dosage is not less than 450 kg / m (adjusted according to the actual situation if the geological conditions are complex), and the water-cement ratio w / c = 0.9 to 1.1.

[0083] (3) Drill rod speed: The drilling and hoisting speed is 0.1 to 0.2 m / min.

[0084] (4) Water delivery pressure: 20-24 MPa, slurry delivery pressure: 24-26 MPa.

[0085] (5) The diameter of the enlarged hole is ≥1000mm and the deviation of the pile diameter (D) is ≤50mm.

[0086] (6) The drilling position deviation is ≤50mm, and the allowable deviation of the pile center is ≤0.2D, where D is the pile diameter.

[0087] (7) Drilling verticality ≤ 1.5%

[0088] (8) Hole depth deviation ±200mm.

[0089] The main construction processes for the first plain concrete pile 2 and the second plain concrete pile 4 are as follows:

[0090] 1. Determine the pile bottom depth: Use a level to measure the natural ground elevation at the construction site, and calculate the actual depth of penetration into the soil based on the designed pile top and bottom elevations. Use a depth gauge on the frame to control the depth, with an accuracy of ±100mm.

[0091] 2. Positioning and Alignment: When positioning, ensure that the four legs of the frame are evenly grounded. Use the plumb line on the frame for bidirectional control to ensure that the verticality is ≤0.1%. When aligning, first adjust the depth gauge according to the ground elevation of the site, and then align the drill bit with the pile position. The alignment accuracy should be controlled within ±10mm.

[0092] 3. Preparation of cement slurry: Based on the cement and water usage parameters obtained from the test piles, divide the cement into several equal portions and pour them into the mixing tank for continuous stirring, and use a hydrometer to control the water-cement ratio.

[0093] 4. Water-jet drilling and pilot hole preparation: According to the given construction parameters, inject water at low pressure into the empty pile section. Stop water injection when drilling to 0.5m above the designed pile top elevation. Stop drilling after drilling to the designed pile bottom elevation. Then, spray grout while rotating and lifting.

[0094] 5. Grouting and Rotation Lifting: When the drilling depth reaches 0.5m above the design elevation of the pile bottom, stop injecting clean water. At the same time, inject high-pressure grout. After drilling to the design elevation of the pile bottom, stop drilling and then rotate and lift while grouting.

[0095] 6. Repeated jet grouting and mixing: When the drill rod is raised to 80cm below the top elevation of the pile, it is lowered back down to the bottom of the pile, and then jet grouting is performed and raised again. During this lowering, the grouting pressure is controlled at 4.0-6.0 MPa, and during the raising, the grouting pressure is controlled at 22-24 MPa. The length of the repeated jet grouting is 4m.

[0096] 7. Backfilling: Use the pure cement slurry returned during construction to backfill the previous pile.

[0097] The technical measures to ensure the forming quality of the first plain concrete pile 2 and the second plain concrete pile 4 are as follows:

[0098] 1. Measures to ensure accurate pile location

[0099] (1) The pile positions are laid out by professional surveyors and the results are verified by the supervisor.

[0100] (2) After the drilling rig is installed and positioned stably, the drill bit must be accurately aligned with the pile position. The quality inspector must check and the supervising engineer must approve before drilling can begin.

[0101] 2. Ensure the nozzle is clear: Before the drill bit sinks, perform a test spray to check and prevent the nozzle from becoming clogged.

[0102] 3. Measures to ensure the verticality of the pile body

[0103] (1) The drilling rig must be leveled before drilling begins, with the lines hanging on both sides of the frame perpendicular to the frame.

[0104] (2) If the drilling rig sinks or tilts during the drilling process, it needs to be adjusted in time.

[0105] 4. Measures to ensure pile length

[0106] (1) After each pile location is determined, the ground elevation is accurately measured using a level, the drilling depth and the starting depth of the air jet section are calculated, and marked on the construction sign.

[0107] (2) Before each drilling session, the depth gauge pointer should be zeroed to ensure accurate drilling depth.

[0108] 5. Measures to improve pile head strength

[0109] (1) Re-spray the upper part of the pile body.

[0110] (2) Recharge in time to keep the hole full of water and mud.

[0111] 6. Measures to prevent mud inclusion and shrinkage in the pile body, ensuring pile quality.

[0112] (1) For silty clay layers with high viscosity, reduce the drill bit advance and increase the drill bit rotation speed, and increase the hole enlargement once.

[0113] (2) Add appropriate stirring blades.

[0114] (3) Increase the nozzle working radius and adopt a dual-nozzle improved drill bit.

[0115] 7. Ensure the amount of grout in the pile body and the quality of the backfill grout.

[0116] (1) Regularly check the grout return of individual piles. A grout return rate of 8-12% is normal. If there is no grout return or the grout return rate is large, the cause should be investigated.

[0117] (2) After the pile is completed, cover the hole opening with tools in time to prevent the slurry from flowing in.

[0118] (3) The cement grout that emerges during the re-grouting process should be used for backfilling.

[0119] 8. Measures to ensure the quality of slurry preparation

[0120] (1) The slurry preparation must be strictly in accordance with the ratio, the material must be fed evenly, the specific gravity of the slurry must be checked and measured frequently, and records must be kept.

[0121] (2) The cement slurry should be thoroughly mixed and fed into the slurry pipe through a filter screen to prevent clogging of the nozzle.

[0122] 9. Measures to prevent cross-hole penetration

[0123] The two-phase construction method is adopted, that is, the piles are alternated by one pile.

[0124] The construction of support pile 1 is as follows:

[0125] Support pile 1 adopts rotary drilling and grouting pile construction technology, with pile diameters of 1000mm, 1300mm, 1500mm and 2000mm respectively. The concrete strength grade of the pile body is underwater C30 and underwater C20 ultra-slow setting; ready-mixed concrete is used, and the concrete slump is 180mm~220mm.

[0126] The longitudinal reinforcing bars of support pile 1 are HRB400 grade steel bars. A reinforced concrete capping beam is provided at the top of support pile 1, and the main reinforcement bars of support pile 1 should be anchored into the capping beam for no less than 700mm. Spiral stirrups are used, made of HRB400 grade steel bars with a diameter of 10mm and a spacing of 60mm, 90mm, 110mm, 120mm, and 130mm. The reinforcing stirrups along the pile body are made of HRB400 grade steel bars with a diameter of 20mm, 22mm, 25mm, and 28mm and a spacing of 2000mm. The protective layer thickness of the longitudinal reinforcing bars is not less than 50mm. The joints of the longitudinal reinforcing bars should not be located in areas with large internal forces, i.e., within 3m above the bottom of the pit. Within the same connection section, the longitudinal reinforcing bars are connected by lap welding, with a welding length of not less than 10d for single-sided welds and not less than 5d for double-sided welds. The number of joints of the main reinforcement bars on the same cross-section shall not exceed 50% of the total number of main reinforcement bars.

[0127] The support piles 1 adopt the construction sequence of intermittent piles. For concrete cast-in-place piles, the drilling of adjacent piles should be carried out after the concrete has set. The interval between piles shall not be less than three.

[0128] The allowable deviation for the construction position of the support pile 1 should be 50mm; the allowable deviation for the verticality of the pile should be 0.5%.

[0129] As a preferred implementation, based on the above method, the second plain concrete pile 4 is constructed by pouring ultra-slow-setting concrete, and the support pile 1 is constructed before the initial setting of the concrete in the second plain concrete pile 4.

[0130] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A water-stop curtain combining high-pressure jet grouting piles and reinforced concrete piles, characterized in that, It includes several support piles and several first plain concrete piles. The support piles are set along the outer edge of the pit wall and are used to bear the lateral rock and soil pressure of the pit. The first plain concrete piles are set on the side of the support piles away from the pit. The several first plain concrete piles interlock with each other to form a curtain structure to prevent water in the rock and soil outside the pit from seeping into the pit. The first plain concrete pile is inclined, with its root side close to the support pile and its head side away from the support pile. The root side of the first plain concrete pile is in contact with the support pile, thereby sealing the bottom of the first plain concrete pile and the support pile and preventing water from seeping from the pile bottom into the soil layer between the first plain concrete pile and the support pile. A second plain concrete pile is also provided between the support piles, and the second plain concrete pile interlocks with the support pile.

2. The water-stop curtain combining high-pressure jet grouting piles and reinforced concrete piles according to claim 1, characterized in that, The interlocking joints between the first plain concrete piles correspond to the pile bodies of the support piles.

3. The water-stop curtain combining high-pressure jet grouting piles and reinforced concrete piles according to claim 2, characterized in that, The bottom elevation of the first plain concrete pile is lower than that of the bottom elevation of the support pile.

4. The water-stop curtain combining high-pressure jet grouting piles and reinforced concrete piles according to claim 3, characterized in that, The first plain concrete pile has several enlarged sections spaced apart on its body, and the diameter of the enlarged sections is larger than the diameter of the plain concrete pile body.

5. The water-stop curtain combining high-pressure jet grouting piles and reinforced concrete piles according to claim 4, characterized in that, The portion of the first plain concrete pile located below the bottom elevation of the support pile is designated as the enlarged section.

6. The water-stop curtain combining high-pressure jet grouting piles and reinforced concrete piles according to claim 5, characterized in that, The diameter of the second plain concrete pile is smaller than that of the support pile; the interlocking area between the second plain concrete pile and the support pile is greater than or equal to 1 / 2 of its own cross-sectional area.

7. A method for constructing a water-stop curtain combining high-pressure jet grouting and reinforced concrete piles, characterized in that, The application to the construction of a water-stop curtain as described in any one of claims 1-6 includes the following steps: Step A, Construction of the second plain concrete pile: Construct the second plain concrete pile along the edge of the pit wall to form a row of piles arranged at intervals; Step B, Construction of support piles: Support piles are constructed between adjacent second plain concrete piles to form an interlocking structure between the support piles and the second plain concrete piles. Step C, Construction of the first plain concrete pile: The first plain concrete pile is constructed on the side away from the foundation pit from the second plain concrete pile and the support pile, so that the first plain concrete pile forms an interlocking curtain structure. The support piles were constructed using rotary drilling and grouting technology, while the first plain concrete pile and the second plain concrete pile were constructed using high-pressure jet grouting technology. The second plain concrete pile was constructed using ultra-slow-setting concrete, and the support piles were completed before the initial setting of the second plain concrete pile.

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