Construction method for curing mud skin by post grouting of pile side of bored pile
By installing annular and vertical grouting pipes on the reinforcing cage of the cast-in-place pile, grout is injected into the soil layer along the pile to solidify the mud cake, which solves the problems of reduced frictional resistance and insufficient bearing capacity caused by mud wall protection, and achieves the strengthening of the soil layer along the pile and the improvement of cohesion.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHENZHEN HONGYEJI GEOTECHNICAL TECH CO LTD
- Filing Date
- 2023-12-28
- Publication Date
- 2026-05-29
AI Technical Summary
In existing technologies, cast-in-place piles formed by mud slurry wall protection suffer from reduced pile side friction and insufficient single pile bearing capacity.
A ring-shaped grouting pipe and a vertical grouting pipe are installed on the reinforcing cage of the cast-in-place pile. After the grouting is completed, grout is injected to the outer perimeter through the vertical grouting pipe. The grout mixes with the soil layer on the pile side, solidifies the mud cake, and improves the strength and cohesion of the soil layer on the pile side.
High-pressure grouting solidifies the mud cake, enhancing the density and strength of the soil layer along the pile, increasing pile side resistance, and reducing building settlement.
Smart Images
Figure CN117802988B_ABST
Abstract
Description
Technical Field
[0001] This invention patent relates to the technical field of cast-in-place piles, and more specifically, to a method for constructing a grouting and solidifying mud cake on the side of a cast-in-place pile. Background Technology
[0002] A cast-in-place pile is a type of pile made by drilling a hole in place and then pouring in concrete or reinforced concrete.
[0003] In existing technologies, since bored piles are mostly drilled in loose soil layers with poor borehole wall integrity, mud slurry is generally used for wall protection to prevent borehole collapse. During the mud slurry wall protection process, mud particles adhere to the borehole wall to form a mud cake, which hinders the cohesion between the pile concrete and the surrounding soil. This is equivalent to applying a layer of lubricant to the pile side, greatly reducing the frictional resistance of the pile side. At the same time, for water-sensitive strata, the soil softens due to long-term soaking, which also reduces the frictional resistance of the surrounding soil. Secondly, the pile concrete will also shrink in volume after consolidation, creating gaps between the pile concrete and the borehole wall, reducing the frictional resistance of the pile side and lowering the bearing capacity of a single pile. Summary of the Invention
[0004] The purpose of this invention is to provide a method for constructing a post-grouting and solidification mud cake on the side of a cast-in-place pile, which aims to solve the problem that the bearing capacity of a single pile is reduced when using mud slurry to form a cast-in-place pile in the prior art.
[0005] This invention is implemented as follows: a method for constructing a post-grouting and solidification mud cake on the side of a cast-in-place pile, comprising the following construction steps:
[0006] 1) After the cast-in-place pile is cast in place, the cast-in-place pile has a reinforcing cage and a soil layer around the pile. The reinforcing cage is provided with multiple annular grouting pipes, which are arranged at intervals along the axial direction of the reinforcing cage. Each annular grouting pipe has multiple peripheral grouting ports, which are arranged at intervals along the circumference of the annular grouting pipe. The peripheral grouting ports are exposed between the outer periphery of the cast-in-place pile and the soil layer around the pile.
[0007] Each of the aforementioned annular grouting pipes is connected to a vertical grouting pipe. The bottom of the vertical grouting pipe is connected to the annular grouting pipe, and the top of the vertical grouting pipe extends upward to the top of the cast-in-place pile, forming a grouting port.
[0008] Within 7-8 hours after the cast-in-place pile is cast, the plugs of multiple vertical grouting pipes and multiple annular grouting pipes are opened.
[0009] 2) After the cast-in-place pile has been cast and formed for 48 hours, grout is injected into the multiple annular grouting pipes in a vertical direction from top to bottom. The grout enters the space between the outer periphery of the cast-in-place pile and the soil on the side of the pile, and mixes with the mud skin on the outer periphery of the cast-in-place pile. After the grout hardens, the mud skin on the outer periphery of the cast-in-place pile is solidified.
[0010] Optionally, in construction step 2), the grout is formed by mixing 30% to 45% silicate cement, 55% to 65% mineral powder, 30% to 40% fly ash and 5% to 10% liquid water glass according to the mass ratio.
[0011] Optionally, in construction step 2), the clinker strength of the silicate cement is not less than 42.5 MPa, and the specific surface area of the silicate cement is ≥400 m². 2 / kg.
[0012] Optionally, the ore powder is granulated blast furnace slag powder in powder form, and the specific surface area of the ore powder is ≥500m². 2 / kg, the 7-day activity index of the mineral powder is not less than 75%.
[0013] Optionally, the fly ash is in powder form, and the specific surface area of the fly ash is ≥400m². 2 / kg.
[0014] Optionally, the modulus of the liquid water glass is between 2.5 and 2.8.
[0015] Optionally, in construction step 2), the process of injecting grout into the annular grouting pipe through the vertical grouting pipe is divided into an initial stage, an intermediate stage, and an ending stage. The grouting pressure in the initial stage and the ending stage is between 1.8 MPa and 2.5 MPa, and the grouting pressure in the intermediate stage is between 0.5 MPa and 1.0 MPa.
[0016] Optionally, in construction step 2), the grouting is stopped when the grouting volume of the plurality of annular grouting pipes reaches the set total grouting volume, or when the grouting volume of the plurality of annular grouting pipes reaches 80% of the set total grouting volume and the grouting pressure is greater than the set pressure value.
[0017] Optionally, in construction step 1), a tee connector is provided, wherein each end of the tee structure has an end pipe, and the middle of the tee connector has a middle pipe; the two ends of the annular grouting pipe are respectively connected to the two end pipes, the bottom of the vertical grouting pipe is connected to the middle pipe, and the vertical grouting pipe is connected to the annular grouting pipe through the tee connector.
[0018] The bottom of the vertical grouting pipe has an injection port, the middle of the injection port has a central opening and an outer ring, the inner side of the outer ring surrounds the outer circumference of the central opening, and the outer side of the outer ring is connected to the outer circumference of the injection port; the central opening is connected to an inner pipe, which is arranged around the circumference of the annular grouting pipe and has a grouting interval between it and the inner wall of the annular grouting pipe.
[0019] The inner tube has an inner cavity, and both ends of the inner tube are respectively connected to the central opening and are respectively connected to the central opening. The middle part of the inner tube has a flat strip-shaped internal grouting port, which is arranged in a flat strip shape along the circumference of the inner tube. The outer circumference ring is provided with multiple annular grouting ports, which are arranged at intervals along the circumference of the outer circumference ring.
[0020] In construction step 2), the grout is injected downward through the vertical grouting pipe. The grout enters the annular grouting pipe through multiple annular grouting ports on the outer circumference. The grout enters the inner pipe through the central port and then enters the annular grouting pipe through the inner grouting port of the inner pipe. The grout is injected into the annular grouting pipe from multiple directions by the annular grouting ports and the inner grouting ports, and is ejected from the outer circumference grouting ports of the annular grouting pipe.
[0021] Optionally, the outer grouting port is formed on the outside of the annular grouting pipe, and the inner wall of the annular grouting pipe has a positive alignment, which is covered with an elastic and raised airbag layer; the inner tube is fixed to the top inside the annular grouting pipe, and the inner tube and the raised airbag layer are offset vertically, with the inner grouting port facing downward.
[0022] In construction step 2), after the grout enters the interior of the annular grouting pipe, the grout presses against the protruding airbag layer and compresses and deforms it. The protruding airbag layer recovers its deformation and reverses the direction, driving the grout to spray outward toward the outer grouting hole.
[0023] Compared with existing technologies, the post-grouting and solidification mud cake construction method for cast-in-place piles provided by this invention involves fixing an annular grouting pipe to the reinforcing cage. After the cast-in-place pile is formed, grout is injected through the vertical grouting pipe, causing the grout to spray from the outer grouting port towards the soil layer beside the pile. When grouting in the coarse-grained soil layer beside the pile, the grout reduces the porosity and increases the density of the soil layer through penetration, partial compaction, filling, and consolidation, exhibiting a penetration-filling cementing effect. Simultaneously, when grouting in the fine-grained soil layer beside the pile, the grouting pressure exceeds the splitting pressure, causing hydraulic splitting of the soil, exhibiting a splitting reinforcement effect. In this way, the soil layer beside the pile is restored to its original state, and its strength is improved. Furthermore, the grout fills the gap between the pile concrete and the soil layer beside the pile, increasing the bond strength between the pile and the soil, thereby increasing the pile side resistance. In summary, high-pressure grouting is performed on the mud skin and soil on the side of the cast-in-place pile through pre-embedded annular grouting pipes and vertical grouting pipes to remove or improve the mud skin. The mud skin is then replaced by grout, reducing the negative impact of the mud skin on the pile side and thus reducing the settlement of the building. Attached Figure Description
[0024] Figure 1 This is a schematic diagram of the structure of the cast-in-place pile provided by the present invention;
[0025] Figure 2 This is a schematic diagram showing the connection of the annular grouting pipe, the vertical grouting pipe, and the tee joint provided by the present invention;
[0026] Figure 3 This is a cross-sectional schematic diagram of the annular grouting pipe, the vertical grouting pipe, and the tee joint provided by the present invention;
[0027] Figure 4 This is a cross-sectional schematic diagram of the annular grouting pipe provided by the present invention. Detailed Implementation
[0028] 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.
[0029] The implementation of the present invention will be described in detail below with reference to specific embodiments.
[0030] In the accompanying drawings of this embodiment, the same or similar reference numerals correspond to the same or similar components. In the description of this invention, it should be understood that if terms such as "upper," "lower," "left," and "right" 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 invention 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, the terms used to describe positional relationships in the accompanying drawings are only for illustrative purposes and should not be construed as limiting this patent. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.
[0031] Reference Figure 1-4 The image shown is a preferred embodiment of the present invention.
[0032] The present invention provides a method for constructing a post-grouting and solidification mud cake on the side of a cast-in-place pile, comprising the following construction steps:
[0033] 1) After the cast-in-place pile is cast in place, it has a steel cage and a soil layer 10 on the side of the pile. The steel cage is provided with multiple annular grouting pipes 100, which are arranged at intervals along the axial direction of the steel cage. The annular grouting pipes 100 have multiple peripheral grouting ports 101, which are arranged at intervals along the circumference of the annular grouting pipes 100. The peripheral grouting ports 101 are exposed between the outer periphery of the cast-in-place pile and the soil layer 10 on the side of the pile.
[0034] Each annular grouting pipe 100 is connected to a vertical grouting pipe 200. The bottom of the vertical grouting pipe 200 is connected to the annular grouting pipe 100, and the top of the vertical grouting pipe 200 extends upward to the top of the cast-in-place pile, forming a grouting port.
[0035] Within 7-8 hours after the cast-in-place pile is cast, the plugs on multiple vertical grouting pipes 200 and multiple annular grouting pipes 100 are opened.
[0036] 2) 48 hours after the cast-in-place pile is cast, grout is injected sequentially into the multiple annular grouting pipes 100 from top to bottom through the vertical grouting pipe 200. The grout enters the space between the outer periphery of the cast-in-place pile and the soil on the side of the pile, and mixes with the mud skin on the outer periphery of the cast-in-place pile. After the grout hardens, the mud skin on the outer periphery of the cast-in-place pile is solidified.
[0037] The above-described method for grouting and solidifying the mud cake on the side of cast-in-place piles involves fixing an annular grouting pipe 100 to the reinforcing cage. After the cast-in-place pile is formed, grout is injected through the vertical grouting pipe 200, causing the grout to spray from the outer grouting port 101 towards the soil layer 10 on the side of the pile. When grouting in the coarse-grained soil layer 10, the grout, through penetration, partial compaction, filling, and consolidation, reduces the porosity and increases the density of the soil layer 10, exhibiting a penetration-filling and cementing effect. Simultaneously, when grouting in the fine-grained soil layer 10, the grouting pressure exceeds the splitting pressure, causing hydraulic splitting of the soil, exhibiting a splitting reinforcement effect. In this way, the soil layer 10 on the side of the pile is restored to its original state, and its strength is improved. Furthermore, the grout fills the gap between the pile concrete and the soil layer 10 on the side of the pile, increasing the bond strength between the pile and the soil, thereby increasing the pile side resistance. In summary, high-pressure grouting is performed on the mud skin and soil on the side of the cast-in-place pile through the pre-embedded annular grouting pipe 100 and vertical grouting pipe 200 to remove or improve the mud skin. The mud skin is then replaced by grout, reducing the negative impact of the mud skin on the pile side and thus reducing the settlement value of the building.
[0038] Specifically, five peripheral grouting ports 101 are drilled evenly along the circumferential direction of the annular grouting pipe 100 using a drilling rig. After drilling, large thumbtacks are inserted and sealed with transparent tape.
[0039] Specifically, compared with the traditional method of controlling the thickness of the mud skin by simply preparing high-quality mud slurry, the advantage of this patent is that preparing high-quality mud slurry only makes the mud skin thinner, and the post-grouting of the pile side can destroy and eliminate the mud skin, fill the gaps on the pile side, improve the adhesion between the pile side and the surrounding soil, thereby increasing the pile side friction resistance, increasing the pile diameter, shortening the pile length, and reducing the cost.
[0040] Specifically, the grout penetrates into the soil layer 10 on the side of the pile under high pressure. Since the grouting is all below the ground water level, the grout can hardly penetrate vertically downwards (or it will not continue to penetrate downwards after penetrating a short distance). This is because the pressure is too high as it penetrates downwards, so it can only penetrate in all directions or upwards. If there is not a large channel around it, it can only penetrate upwards along the weak surface of the mud skin on the side of the pile, and finally push the mud skin upwards, flushing it out or reinforcing the mud skin, thus achieving the effect of removing or improving the mud skin.
[0041] In construction step 2), the grout is formed by mixing 30% to 45% silicate cement, 55% to 65% mineral powder, 30% to 40% fly ash and 5% to 10% liquid water glass according to the mass ratio.
[0042] In this way, the addition of mineral powder gives the slurry good permeability.
[0043] Specifically, the hydration reaction of silicate cement: After silicate cement is mixed with water, the minerals in the cement react with the water to form silicate gel and calcium hydroxide. These products further react to form a crystal structure, binding the solid particles together.
[0044] Physical effects of fly ash and mineral powder: Fly ash and mineral powder act as physical fillers in slurry, enhancing the consistency and stability of the slurry.
[0045] Hardening reaction of liquid water glass: Water glass reacts with cement, mineral powder, fly ash and other substances to form silicate gel. These gels fill the spaces between particles, causing the slurry to harden and increasing its strength.
[0046] The filling effect of mineral powder and fly ash: During the hardening process, mineral powder and fly ash will fill each other with water glass and cement hydration products to form a dense network structure, thereby improving the compressive strength, durability and impermeability of the slurry.
[0047] This results in a curing strength far greater than that achieved through pure cement curing.
[0048] As a preferred embodiment, in construction step 2), the clinker strength of the silicate cement is not less than 42.5 MPa, and the specific surface area of the silicate cement is ≥400 m². 2 / kg.
[0049] Specifically, the ore powder is granulated blast furnace slag powder in powder form, with a specific surface area ≥ 500 m². 2 / kg, the 7-day activity index of the mineral powder is not less than 75%.
[0050] In a preferred embodiment, the fly ash is in powder form, and the specific surface area of the fly ash is ≥400m². 2 / kg.
[0051] Specifically, the modulus of liquid water glass is between 2.5 and 2.8.
[0052] Specifically, (5) use clean water to open the grouting device and pressurize the grouting pipeline. The opening pressure is 0.8 to 1.5 MPa. After opening, water injection should be stopped immediately. Grouting is mainly based on grout penetration.
[0053] In construction step 2), the process of injecting grout through the vertical grouting pipe 200 and the annular grouting pipe 100 is divided into an initial stage, an intermediate stage, and a final stage. The grouting pressure in the initial and final stages is between 1.8 MPa and 2.5 MPa, while the grouting pressure in the intermediate stage is between 0.5 MPa and 1.0 MPa. The initial stage of grouting requires a higher pressure to overcome significant initial resistance, while the pressure required during stable grouting is lower. At the final stage, the grout has filled the stratum, requiring a higher pressure. Excessive grouting pressure can easily lead to grout leakage and runoff, while insufficient pressure makes it difficult for the grout to split, compress, and penetrate within the soil and rock.
[0054] In construction step 2), grouting is stopped when the grouting volume injected by the multiple annular grouting pipes 100 reaches the set total grouting volume, or when the grouting volume injected by the multiple annular grouting pipes 100 reaches 80% of the set total grouting volume and the grouting pressure is greater than the set pressure value. Thus, grouting can be terminated when either of these conditions is met.
[0055] In this embodiment, in construction step 1), a tee connector 300 is provided, with end pipes 310 at both ends of the tee structure and a middle pipe 320 in the middle of the tee connector 300; the two ends of the annular grouting pipe 100 are respectively connected to the two end pipes 310, and the bottom of the vertical grouting pipe 200 is connected to the middle pipe 320; the vertical grouting pipe 200 is connected to the annular grouting pipe 100 through the tee connector 300.
[0056] The bottom of the vertical grouting pipe 200 has an injection port, the middle of the injection port has a central opening and an outer ring 400, the inner side of the outer ring 400 surrounds the outer circumference of the central opening, and the outer side of the outer ring 400 is connected to the outer circumference of the injection port; the central opening is connected to an inner pipe 410, which is arranged around the circumference of the annular grouting pipe 100 and has a grouting interval between it and the inner wall of the annular grouting pipe 100.
[0057] The inner tube 410 has an inner cavity. Both ends of the inner tube 410 are respectively connected to the central opening and are respectively connected to the central opening. The middle part of the inner tube 410 has a flat strip-shaped internal grouting port 411, which is arranged in a flat strip shape along the circumference of the inner tube 410. The outer circumferential ring 400 is provided with multiple annular grouting ports 401, which are arranged at intervals along the circumference of the outer circumferential ring 400.
[0058] In construction step 2), the grout is injected downwards through the vertical grouting pipe 200. The grout enters the annular grouting pipe 100 through multiple annular grouting ports 401 on the outer ring 400, then enters the inner pipe 410 through the central port, and finally enters the annular grouting pipe 100 through the inner grouting port 411 of the inner pipe 410. The grout is injected into the annular grouting pipe 100 from multiple directions via the annular grouting ports 401 and the inner grouting ports 411, and is ejected from the outer grouting ports 101 of the annular grouting pipe 100. By setting the position of the inner grouting ports 411, the direction of the grout entering the annular grouting pipe 100 can be effectively controlled, creating a counter-current injection pattern with the grout entering through the annular grouting ports 401. This effectively avoids the problem of significant pressure differences among the multiple outer grouting ports 101, allowing the grout to be sprayed more evenly onto the soil layer 10 beside the pile.
[0059] In a preferred embodiment, the outer grouting port 101 is formed on the outer side of the annular grouting pipe 100, and the inner sidewall of the annular grouting pipe 100 has a positive alignment, which is covered with an elastic and raised airbag layer 110; the inner pipe 410 is fixed to the top inside the annular grouting pipe 100, and the inner pipe 410 and the raised airbag layer 110 are offset vertically, with the inner grouting port 411 facing downward.
[0060] In construction step 2), after the grout enters the interior of the annular grouting pipe 100, the grout compresses and deforms against the raised airbag layer 110. The raised airbag layer 110 then recovers its deformation and reverses the deformation, driving the grout to spray outwards towards the outer grouting holes. In this way, by utilizing the raised airbags to cause the grout to change its flow direction, the energy loss caused by the grout's impact is reduced, thereby increasing the pressure of the ejected grout to achieve the effect of removing or improving the mud cake.
[0061] 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 method for constructing a grouting and solidification mud cake on the side of a cast-in-place pile, characterized in that, The construction steps include the following: 1) After the cast-in-place pile is cast in place, the cast-in-place pile has a reinforcing cage and a soil layer around the pile. The reinforcing cage is provided with multiple annular grouting pipes, which are arranged at intervals along the axial direction of the reinforcing cage. Each annular grouting pipe has multiple peripheral grouting ports, which are arranged at intervals along the circumference of the annular grouting pipe. The peripheral grouting ports are exposed between the outer periphery of the cast-in-place pile and the soil layer around the pile. Each of the aforementioned annular grouting pipes is connected to a vertical grouting pipe. The bottom of the vertical grouting pipe is connected to the annular grouting pipe, and the top of the vertical grouting pipe extends upward to the top of the cast-in-place pile, forming a grouting port. Within 7-8 hours after the cast-in-place pile is cast, the plugs of multiple vertical grouting pipes and multiple annular grouting pipes are opened. 2) 48 hours after the cast-in-place pile is cast, grout is injected into the multiple annular grouting pipes in sequence from top to bottom through the vertical grouting pipes. The grout enters the space between the outer periphery of the cast-in-place pile and the soil on the side of the pile, and mixes with the mud skin on the outer periphery of the cast-in-place pile. After the grout hardens, the mud skin on the outer periphery of the cast-in-place pile is solidified. In construction step 1), a tee connector is provided, with end pipes at both ends and a middle pipe in the middle; the two ends of the annular grouting pipe are respectively connected to the two end pipes, the bottom of the vertical grouting pipe is connected to the middle pipe, and the vertical grouting pipe is connected to the annular grouting pipe through the tee connector. The bottom of the vertical grouting pipe has an injection port, the middle of the injection port has a central opening and an outer ring, the inner side of the outer ring surrounds the outer circumference of the central opening, and the outer side of the outer ring is connected to the outer circumference of the injection port; the central opening is connected to an inner pipe, the inner pipe is arranged around the circumference of the annular grouting pipe, and there is a grouting interval between the inner pipe and the inner wall of the annular grouting pipe. The inner tube has an inner cavity, and both ends of the inner tube are respectively connected to the central opening and are respectively connected to the central opening. The middle part of the inner tube has a flat strip-shaped internal grouting port, which is arranged in a flat strip shape along the circumference of the inner tube. The outer circumference ring is provided with multiple annular grouting ports, which are arranged at intervals along the circumference of the outer circumference ring. In construction step 2), the grout is injected downwards through a vertical grouting pipe. The grout enters the annular grouting pipe through multiple annular grouting ports on the outer circumference. The grout enters the inner pipe through the central port and then enters the annular grouting pipe through the inner grouting port of the inner pipe. The grout is injected into the annular grouting pipe from multiple directions through the annular grouting ports and the inner grouting ports, and is ejected from the outer circumference grouting ports of the annular grouting pipe. The outer grouting port is formed on the outside of the annular grouting pipe. The inner wall of the annular grouting pipe has a corresponding position, and the corresponding position is covered with an elastic and raised airbag layer. The inner tube is fixed to the top inside the annular grouting pipe. The inner tube and the raised airbag layer are offset vertically, and the inner grouting port is arranged downward. In construction step 2), after the grout enters the interior of the annular grouting pipe, the grout presses against the protruding airbag layer and compresses and deforms it. The protruding airbag layer recovers its deformation and reverses the direction, driving the grout to spray outward toward the outer grouting hole.
2. The method for constructing a post-grouting and solidification mud cake on the side of a cast-in-place pile as described in claim 1, characterized in that, In construction step 2), the process of injecting grout into the annular grouting pipe through the vertical grouting pipe is divided into an initial stage, an intermediate stage, and an ending stage. The grouting pressure in the initial stage and the ending stage is between 1.8 MPa and 2.5 MPa, and the grouting pressure in the intermediate stage is between 0.5 MPa and 1.0 MPa.
3. The method for constructing a post-grouting and solidification mud cake on the side of a cast-in-place pile as described in claim 1, characterized in that, In construction step 2), when the grouting volume of the multiple annular grouting pipes reaches the set total grouting volume, or when the grouting volume of the multiple annular grouting pipes reaches 80% of the set total grouting volume and the grouting pressure is greater than the set pressure value, the grouting is stopped.