Multi-media high-pressure hole washing and slurry sealing grouting repair method for cast-in-place pile bottom sediment

Abstract

The invention relates to the technical field of cast-in-place pile repair, and discloses a cast-in-place pile bottom sediment multi-media high-pressure hole washing and slurry closed grouting repair method, comprising the following construction steps: 1) starting an air compressor to perform high-air pressure hole washing; 2) starting the air compressor and the grouting pump respectively to perform high-air pressure and high-water pressure mixed hole washing; 3) the grouting pump injects cement slurry into the core pulling hole, and the grouting pump is replaced with an air compressor, and the air compressor delivers high-compressed air into the core pulling hole; 4) the air compressor is replaced with a grouting pump again, and cement slurry is injected into the core pulling hole; 5) the core pulling hole is sealed and grouted by an expansion sealer; the core pulling hole is used as a channel, and single media and multi-media mixed hole washing such as water, air, and slurry are used to clean the pile bottom sediment, and high-pressure closed grouting is used to fill the pile bottom sediment section, the core pulling hole, the pile body, and the slightly weathered rock cracks with cement slurry densely, thereby achieving the effect of repairing the sediment defect pile.

Description

Technical Field

[0001] The invention relates to the technical field of bored pile repair, in particular to a method for repairing bored pile bottom sediment by multi-medium high-pressure hole washing and slurry sealing grouting. Background Art

[0002] A cast-in-place pile is a pile made by drilling a hole in place and pouring concrete or reinforced concrete.

[0003] At present, when conducting quality inspections on cast-in-place piles, excessive thickness of pile bottom sediment is one of the common quality defects. How to effectively treat the pile bottom sediment so that it meets the design requirements after repair is a major problem currently faced.

[0004] In the existing technology, when the thickness of the sediment at the bottom of the bored pile exceeds the standard, high-pressure rotary jet washing and high-pressure grouting are usually used for treatment. This process uses wind pressure washing and ordinary cement slurry as the grouting body. After the treatment, it needs to be cured for a long time before the treatment effect can be tested. There are disadvantages such as incomplete treatment of the sediment at the bottom of the pile and poor repair effect of the grouting body. Summary of the Invention

[0005] The purpose of the present invention is to provide a multi-media high-pressure hole washing and slurry closed grouting repair method for cast-in-place pile bottom sediment, aiming to solve the problems of incomplete sediment treatment and poor repair effect of cast-in-place piles in the prior art.

[0006] The present invention is achieved by a multi-medium high-pressure hole washing and slurry sealing grouting repair method for cast-in-place pile bottom sediment, comprising the following construction steps:

[0007] 1) Drill a hole on the cast-in-place pile to the bedrock, remove the core rod by core extraction, and form a core extraction hole on the cast-in-place pile. Place the slotted hole washer in the air compressor into the core extraction hole through a high-pressure pipe, inject clean water into the core extraction hole, start the air compressor to perform high-pressure hole washing, and keep the slotted hole washer lowered synchronously until the sediment section;

[0008] Highly compressed air passes through the interior of the high-pressure pipe and enters the slotted hole washer, and then is ejected from the slotted hole washer toward the core-pulling hole, ejecting the sewage in the core-pulling hole outward until the sewage becomes clear water;

[0009] 2) Pull the high-pressure air pipe and the slotted hole washer out of the core pulling hole, inject cleaning liquid into the core pulling hole and soak it for a set time; put one end of the high-pressure water flow pipe into the core pulling hole, and connect the other end of the high-pressure water flow pipe to the air compressor and the grouting pump through a three-way pipe head, and connect one end of the high-pressure water flow pipe to the open-hole hole washer; start the air compressor and the grouting pump respectively to perform high-pressure air and high-water mixed hole washing, and keep the open-hole hole washer lowered synchronously until it reaches the sediment section;

[0010] The high-pressure water flow passes through the high-pressure water flow pipe and enters the open-hole type hole washer, and then is sprayed from the open-hole type hole washer toward the core pulling hole, spraying out the mud skin, mud blocks and small particles of sediment in the core pulling hole;

[0011] 3) The high-pressure water flow pipe and the open-hole washer are pulled out of the core pulling hole, and the grouting pump injects cement slurry into the core pulling hole through the grouting pipe until the volume of the cement slurry in the core pulling hole reaches a set value; the grouting pump is replaced with an air compressor, and the air compressor delivers high-compressed air into the core pulling hole through the grouting pipe from the slotted hole washer. The high-compressed air fully mixes the cement slurry in the core pulling hole with the small particles of sediment remaining in the core pulling hole, and the mixed cement slurry is ejected from the core pulling hole;

[0012] 4) The air compressor is then replaced with a grouting pump, which injects cement slurry into the core pulling hole through a grouting pipe. The cement slurry is ejected from the slotted hole washer toward the core pulling hole until the cement slurry overflowing from the core pulling hole has the same properties as the cement slurry in the mixing tank.

[0013] 5) The core hole is sealed and grouting is performed by an expansion sealer. The grouting pump injects cement slurry into the core hole through a grouting pipe. The cement slurry is subjected to high pump pressure in a confined space and is pressed into the fine cracks of the pile body and the pile bottom under the action of the high pump pressure until the fine cracks of the pile body and the pile bottom are filled with cement slurry.

[0014] Furthermore, in the construction step 1), the slotted hole washer includes an air jet tube, an exhaust port is provided on the bottom of the air jet tube, and the high air pressure tube is connected to the core pulling hole through the exhaust port; a plurality of open slots are provided on the outer side of the air jet tube, and the plurality of open slots are arranged at intervals along the circumference of the outer side of the air jet tube, and the high air pressure tube is connected to the core pulling hole through the open slots.

[0015] Furthermore, in the construction step 2), the air compressor delivers high air pressure to the three-way pipe head through the high air pressure pipe, and the grouting pump delivers high water pressure to the three-way pipe head through the high water pressure pipe, and the high air pressure and high water pressure form the high-pressure water flow in the high-pressure water flow pipe.

[0016] Furthermore, in the construction step 2), the open-hole washer includes a spray pipe, which is provided with a plurality of side wall holes, and the plurality of side wall holes are arranged circumferentially and spaced apart along the outer side of the spray pipe; the high-pressure water flow pipe is connected to the core pulling hole through the side wall holes.

[0017] Furthermore, in the construction step 3), the grouting is stopped when the grouting volume of the cement slurry reaches 1 / 3 to 1 / 2 of the volume of the core-drawing hole.

[0018] Furthermore, in the construction step 4), the grouting pump is connected to the mixing barrel through a conduit.

[0019] Furthermore, in the construction step 5), the expansion sealer includes a sealing tube that is sealed in the core pulling hole by water injection and expansion, and a delivery pipe connected to the sealing tube, and a water pressure pump is connected to the delivery pipe; the sealing tube is arranged circumferentially along the outer periphery of the grouting tube, and the inner side wall of the sealing tube abuts against the outer periphery of the grouting tube.

[0020] Furthermore, a one-way valve is provided on the delivery pipe, a drain pipe is provided between the one-way valve and the sealing pipe, the drain pipe is connected to the delivery pipe, and a water pressure valve is provided on the drain pipe.

[0021] Furthermore, in the construction step 1), the orifice of the core-pulling hole is inserted into the flow-stopping tube, the bottom of the flow-stopping tube is inserted into the core-pulling hole, and the top of the flow-stopping tube is exposed outside the core-pulling hole.

[0022] Furthermore, the injection pipe is provided with a wall cleaning ring, which is arranged around the outer circumference of the injection pipe. The injection pipe and the wall cleaning ring are connected through a bearing. The wall cleaning ring is provided with a plurality of wiping strips that are bent and extended toward the inner wall of the core pulling hole. The plurality of wiping strips are arranged at intervals along the outer circumference of the wall cleaning ring; the wiping strip has an inner end face facing the side wall hole and an outer end face away from the side wall hole, and an elastic friction layer is provided on the outer end face, and the friction layer is attached to the inner wall of the core pulling hole; the inner end face has a triangular push block protruding toward the side wall hole, and the triangular push block is arranged relative to the side wall hole, and there is a gap between the two.

[0023] Compared with the existing technology, the multi-media high-pressure hole washing and slurry closed grouting repair method for cast-in-place pile bottom sediment provided by the present invention uses the core extraction hole as a channel, and washes the hole through single media and multi-media mixed holes such as water, air, and slurry to clean the pile bottom sediment, and through high-pressure closed grouting, the pile bottom sediment section, the core extraction hole and the pile body, and the slightly weathered rock cracks are densely filled with cement slurry, thereby achieving the effect of repairing sediment-defective piles, solving the problems of incomplete sediment treatment and poor repair effect of cast-in-place piles. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic diagram of the construction process of the multi-media high-pressure hole washing and slurry sealing grouting repair method for cast-in-place pile bottom sediment provided by the present invention;

[0025] Figure 2 This is a schematic diagram of the structural arrangement of the core pulling holes and the alternating high-pressure washing holes provided by the present invention;

[0026] Figure 3 This is a schematic diagram of the structural arrangement of the high wind pressure and high water pressure mixed alternate hole washing provided by the present invention;

[0027] Figure 4 This is a schematic diagram of the structural arrangement of the core hole plugging grouting provided by the present invention;

[0028] Figure 5 It is a schematic diagram of the structural arrangement of the core pulling hole and the expansion hole sealer provided by the present invention;

[0029] Figure 6 It is a three-dimensional schematic diagram of the slotted hole washer provided by the present invention;

[0030] Figure 7 It is a three-dimensional schematic diagram of the open-hole type hole washer provided by the present invention;

[0031] Figure 8 It is a schematic diagram of the top view of the open-hole washer and the wall cleaning ring provided by the present invention.

[0032] In the figure: core pulling hole 100, air compressor 200, grouting pump 300, high-pressure water flow pipe 400, three-way pipe head 500, open hole type hole washer 600, grouting pipe 700, expansion hole sealer 800, flow stop pipe 900, high air pressure pipe 201, slotted hole washer 202, jet pipe 203, exhaust port 204, open slot 205, high water pressure pipe 301, mixing barrel 302, jet pipe 601, side wall hole 602, wall cleaning ring 603, bearing 604, wiping strip 605, friction layer 606, triangular push block 607, sealing pipe 801, delivery pipe 802, water pressure pump 803, one-way valve 804, drain pipe 805, water pressure valve 806. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present 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 only used to explain the present invention and are not intended to limit the present invention.

[0034] The implementation of the present invention is described in detail below with reference to specific embodiments.

[0035] The same or similar numbers in the drawings of this embodiment correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "up", "down", "left", "right", etc. indicate directions or positional relationships, they are based on the directions or positional relationships shown in the drawings. This is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0036] Reference Figure 1-8 The figure shows a preferred embodiment of the present invention.

[0037] The multi-media high-pressure hole washing and slurry sealing grouting repair method for cast-in-place pile bottom sediment includes the following construction steps:

[0038] 1) Drill a hole to the bedrock on the cast-in-place pile, remove the core rod by core extraction, and form a core-pulling hole 100 on the cast-in-place pile. Place the slotted hole washer 202 in the air compressor 200 into the core-pulling hole 100 through the high-pressure pipe 201, inject clean water into the core-pulling hole 100, start the air compressor 200 to perform high-pressure hole washing, and keep the slotted hole washer 202 lowered synchronously until the sediment section;

[0039] Highly compressed air passes through the interior of the high-pressure pipe 201 and enters the slotted hole washer 202. The air is then ejected from the slotted hole washer 202 toward the core-pulling hole 100, ejecting the wastewater in the core-pulling hole 100 until the wastewater becomes clean water.

[0040] 2) Pull the high-pressure pipe 201 and the slotted hole washer 202 out of the core pulling hole 100, and inject cleaning liquid into the core pulling hole 100 to soak for a set time; put one end of the high-pressure water flow pipe 400 into the core pulling hole 100, and the other end of the high-pressure water flow pipe 400 is connected to the air compressor 200 and the grouting pump 300 respectively through the three-way pipe head 500, and one end of the high-pressure water flow pipe 400 is connected to the open-hole type hole washer 600; start the air compressor 200 and the grouting pump 300 respectively to perform high-pressure and high-water-pressure mixed hole washing, and keep the open-hole type hole washer 600 lowered synchronously until the sediment section;

[0041] The high-pressure water flow passes through the high-pressure water flow pipe 400 and enters the open-hole type hole washer 600, and then is ejected from the open-hole type hole washer 600 toward the core pulling hole 100, ejecting the mud skin, mud blocks and small particles of sediment in the core pulling hole 100.

[0042] 3) The high-pressure water flow pipe 400 and the open-hole washer 600 are pulled out of the core pulling hole 100, and the grouting pump 300 injects cement slurry into the core pulling hole 100 through the grouting pipe 700 until the volume of the cement slurry in the core pulling hole 100 reaches a set value; the grouting pump 300 is replaced with an air compressor 200, and the air compressor 200 delivers high-compressed air into the core pulling hole 100 through the grouting pipe 700 from the slotted hole washer 202. The high-compressed air fully mixes the cement slurry in the core pulling hole 100 with the small particles of sediment remaining in the core pulling hole 100, and the mixed cement slurry is ejected from the core pulling hole 100;

[0043] 4) Replace the air compressor 200 with a grouting pump 300, and inject cement slurry into the core pulling hole 100 through the grouting pipe 700. The cement slurry is ejected from the slotted hole washer 202 toward the core pulling hole 100 until the cement slurry overflowing from the orifice of the core pulling hole 100 has the same properties as the cement slurry in the mixing barrel 302.

[0044] 5) The core hole 100 is sealed and grouting is performed by the expansion sealer 800, and the grouting pump 300 injects cement slurry into the core hole 100 through the grouting pipe 700. The cement slurry is subjected to high pump pressure in the confined space, and then is pressed into the fine cracks of the pile body and the pile bottom under the action of the high pump pressure until the fine cracks of the pile body and the pile bottom are filled with cement slurry.

[0045] The above-mentioned multi-media high-pressure hole washing and slurry closed grouting repair method for cast-in-place pile bottom sediment uses the core extraction hole 100 as a channel, and washes the hole through single media and multi-media mixed with water, air, slurry, etc. to clean the pile bottom sediment, and through high-pressure closed grouting, the pile bottom sediment section, the core extraction hole 100 and the pile body, and the slightly weathered rock cracks are densely filled with cement slurry, thereby achieving the effect of repairing sediment-defective piles, solving the problems of incomplete sediment treatment and poor repair effect of cast-in-place piles.

[0046] In this embodiment, in construction step 1), the slotted hole washer 202 includes an air jet tube 203, an exhaust port 204 is provided on the bottom of the air jet tube 203, and the high air pressure tube 201 is connected to the core pulling hole 100 through the exhaust port 204; a plurality of open slots 205 are provided on the outer side of the air jet tube 203, and the plurality of open slots 205 are arranged at intervals along the circumference of the outer side of the air jet tube 203, and the high air pressure tube 201 is connected to the core pulling hole 100 through the open slots 205.

[0047] The jet pipe 203 can spray the highly compressed air generated by the air compressor 200 directly into the core pulling hole 100 through the exhaust port 204 and multiple open slots 205, so that the water in the core pulling hole 100 is pushed by the highly compressed air and generates upward jet kinetic energy, which carries the sediment out of the core pulling hole 100 in the form of a high-pressure water jet through the jet kinetic energy.

[0048] In this embodiment, in construction step 2), the air compressor 200 delivers high air pressure to the three-way pipe head 500 through the high air pressure pipe 201, and the grouting pump 300 delivers high water pressure to the three-way pipe head 500 through the high water pressure pipe 301. The high air pressure and high water pressure form a high-pressure water flow in the high-pressure water flow pipe 400.

[0049] The high-pressure water flow is sent to the open-hole washer 600 connected at the end through the high-pressure water flow pipe 400 and sprayed out. The high-pressure water flow causes the water in the core pulling hole 100 to generate upward spray kinetic energy, and the sediment is carried out from the core pulling hole 100 in the form of a high-pressure water jet through the spray kinetic energy.

[0050] In this embodiment, in construction step 2), the open-hole washer 600 includes a spray pipe 601, which is provided with a plurality of side wall holes 602, and the plurality of side wall holes 602 are arranged circumferentially around the outer side of the spray pipe 601; the high-pressure water flow pipe 400 is connected to the core pulling hole 100 through the side wall holes 602.

[0051] The injection pipe 601 can spray high-pressure water flow directly toward the inner wall of the core pulling hole 100 through multiple side wall holes 602, so that the water in the core pulling hole 100 is pushed by the high-pressure water flow, generating upward injection kinetic energy and driving mud skin, mud blocks and small particles of sediment to be ejected out of the core pulling hole 100.

[0052] In construction step 3), grouting is stopped when the amount of cement slurry injected reaches 1 / 3 to 1 / 2 of the volume of the core-pulling hole 100; this allows space for the cement slurry to fully mix with the sediment in the core-pulling hole 100.

[0053] In construction step 4), the grouting pump 300 is connected to the mixing barrel 302 via a conduit; thus, the grouting pump 300 can deliver the cement slurry in the mixing barrel 302 to the core-pulling hole 100 at high pressure via the conduit.

[0054] In this embodiment, in construction step 5), the expansion sealer 800 includes a sealing tube 801 that is injected with water to expand and seal the core pulling hole 100, and a delivery pipe 802 connected to the sealing tube 801, and a water pressure pump 803 is connected to the delivery pipe 802; the sealing tube 801 is arranged circumferentially along the outer periphery of the grouting pipe 700, and the inner side wall of the sealing tube 801 abuts against the outer periphery of the grouting pipe 700.

[0055] The hydraulic pump 803 injects water into the sealing tube 801 through the delivery pipe 802, so that the sealing tube 801 expands and seals on the inner wall of the core-pulling hole 100. This process and structural arrangement will not affect the use of the grouting tube 700.

[0056] In this embodiment, a one-way valve 804 is provided on the delivery pipe 802 , a drain pipe 805 is provided between the one-way valve 804 and the sealing pipe 801 , the drain pipe 805 is connected to the delivery pipe 802 , and a water pressure valve 806 is provided on the drain pipe 805 .

[0057] The delivery pipe 802 stabilizes the water pressure in the sealing pipe 801 through the one-way valve 804, and the drain pipe 805 is used to drain the water pressure in the sealing pipe 801 so that the sealer and the grouting pipe 700 can be withdrawn from the core pulling hole 100;

[0058] When the water pressure in the sealing tube 801 increases, the water pressure valve 806 discharges the water through the overflow hole, so that the water pressure in the sealing tube 801 remains stable, thereby avoiding damage to the expansion sealer 800 and increasing the safety of the expansion sealer 800.

[0059] In construction step 1), the orifice of the core pulling hole 100 is inserted into the stop tube 900, the bottom of the stop tube 900 is inserted into the core pulling hole 100, and the top of the stop tube 900 is exposed outside the core pulling hole 100; in this way, sediment, sewage, etc. that return from the core pulling hole 100 can be prevented from flowing back into the core pulling hole 100.

[0060] In this embodiment, a wall cleaning ring 603 is provided on the injection tube 601, and the wall cleaning ring 603 is arranged around the outer circumference of the injection tube 601. The injection tube 601 and the wall cleaning ring 603 are connected by a bearing 604. The wall cleaning ring 603 is provided with a plurality of wiping strips 605 that are bent and extended toward the inner wall of the core pulling hole 100, and the plurality of wiping strips 605 are arranged around the outer circumference of the wall cleaning ring 603 at intervals; the wiping strip 605 has an inner end face facing the side wall hole 602 and an outer end face away from the side wall hole 602, and an elastic friction layer 606 is provided on the outer end face, and the friction layer 606 is attached to the inner wall of the core pulling hole 100; the inner end face has a triangular push block 607 protruding toward the side wall hole 602, and the triangular push block 607 and the side wall hole 602 are arranged opposite to each other, and there is a gap between the two.

[0061] When the open-hole washer 600 is lowered into the core pulling hole 100, high-pressure water flow is ejected through the side wall hole 602 on the injection pipe 601, so that the high-pressure water flow pushes the triangular push block 607 to rotate, and the triangular push block 607 cooperates with the bearing 604 to drive the wall cleaning ring 603 to rotate, and the wall cleaning ring 603 uses the friction layer 606 of the wiping strip 605 to rotate and rub the inner wall of the core pulling hole 100 to remove slag, so as to improve the cleaning of the sediment in the core pulling hole 100.

[0062] Construction Process

[0063] 1. Alternate high-pressure washing of core holes

[0064] 1) Use a measuring rope to measure the sediment depth in the core-pulling hole, and wrap red tape around the corresponding length of the high-pressure hose as a mark. The high-pressure hose uses HYDRAULIC HOSE-602-2502-21MPa (codenamed 602, a two-layer steel wire braided hydraulic hose with a nominal inner diameter of 25mm). It is made of steel wire and special synthetic rubber, and has excellent bending resistance, fatigue resistance, and high pressure bearing properties. For ease of use, the same model of high-pressure hose is used for both hole washing and grouting.

[0065] 2) One end of the high-pressure pipe is connected to a slotted hole washer. The slotted hole washer is made of a Φ48mm, 3.0mm thick steel pipe with a length of about 1.5m. The top of the jet pipe is connected to the high-pressure pipe with a threaded connection. The bottom of the jet pipe is open, and four 5mm wide slots are symmetrically opened at the end to increase the spraying area and avoid being blocked by sediment.

[0066] 3) The other end of the high-pressure pipe is connected to the air compressor. The air compressor is HG550-13C, with a power of 132KW, a volume flow of 15m3 / min, and an air pressure of 0.5-1.5MPa during operation;

[0067] 4) To prevent sediment and sewage from flowing back into the core hole during the treatment of defective piles, a stop pipe should be placed on the core hole before construction. The stop pipe should be about 20 cm above the pile top elevation. The slotted hole washer should be lowered while washing, and the jet pipe should be lowered and raised repeatedly to spray and cut until it reaches the sediment depth. The hole opening should correspond to the red tape mark on the high-pressure pipe.

[0068] 5) During the high-pressure hole washing process of the air compressor, intermittent, rotating and continuous high-pressure hole washing methods are adopted until the turbid water flushed out of each hole by high-pressure air becomes clear; when washing the holes, clean water is continuously added to maintain the high-pressure hole washing and slag carrying effect, and the maximum particle size of the washed sediment is about 8 cm.

[0069] 2. Add cleaning solution into the hole and soak

[0070] 1) After washing the hole with high wind pressure, pour the cleaning liquid into the hole. The cleaning liquid is sealed in barrels and the amount poured at one time is about 8L;

[0071] 2) After pouring the cleaning liquid, let it stand for 12 to 24 hours to allow the cleaning liquid to fully penetrate into the mud skin on the hole wall and the mud blocks at the bottom of the pile, causing them to lose their cohesion and disperse and separate into small particles or mud;

[0072] The cleaning fluid is made of penetrant and detergent in a certain proportion. The full name of the penetrant is fatty alcohol polyoxyethylene ether, which is a non-ionic surfactant with good wettability, permeability, emulsification, dispersibility, solubilization and other properties. It can be oriented on the surface of mud blocks and mud skins, so that its surface tension drops rapidly and significantly, and the mud blocks attached to the bottom of the pile and the mud skins on the walls of the core holes are dispersed.

[0073] 3. "High air pressure + high water pressure" mixed hole washing

[0074] 1) To ensure the hole washing effect, after soaking in the cleaning liquid, use a mixture of high water pressure and high air pressure to wash the hole. The grouting pump pumps high water pressure and the air compressor pumps high air pressure, and the high-pressure water flow is formed by connecting the three-way pipe head;

[0075] 2) The high-pressure water flow is connected to the open-hole washer through the high-pressure water flow pipe. The open-hole washer is made of a Φ48mm, 3.0mm thick steel pipe with a length of about 1.5m. The top of the jet pipe is connected to the high-pressure water flow pipe with a threaded connection. The bottom of the jet pipe is flattened and welded closed. Four side wall holes with a diameter of about 10mm are symmetrically opened 100mm from the bottom to concentrate the pressure and form an ultra-high-pressure water jet.

[0076] 3) To ensure the effect of hole washing, the grouting pump adopts BW150 type, power 15KW, input speed 500r / min, inlet diameter 64mm, outlet diameter 32mm, and maximum grouting pressure can reach 10MPa;

[0077] 4) Use an open-hole washer to wash the holes, lowering it while washing. Move the jet pipe up and down during washing to ensure that the hole wall is clean, until it is lowered to the red mark of the pre-pressurized water flow pipe, and all the water sprayed out of each hole is clear water. The sewage sprayed out during the operation is promptly pumped into the grit chamber by a sewage pump. Since the cleaning fluid is added to the hole, the sewage contains a large amount of foam.

[0078] 4. Grouting pump cement slurry grouting

[0079] 1) The cement slurry is mixed with ultra-fine cement and prepared with a high-speed mixer. The slurry is stirred evenly and used immediately after stirring. The slurry is used up before initial setting. The water-cement ratio of grouting is controlled at 0.45, that is, 45kg of clean water is used for every 100kg of cement.

[0080] 2) One end of the grouting pipe is connected to the grouting pump, and the other end of the grouting pipe is connected to the slotted hole washer. The slotted hole washer is lowered to the bottom of the hole to start grouting. The grouting adopts normal pressure, and the grouting volume is 1 / 3 to 1 / 2 of the core hole volume.

[0081] 5. Air compressor high pressure cement slurry hole washing

[0082] 1) After grouting with normal pressure pump, remove the grouting pipe of the grouting pump and install it to the air compressor interface;

[0083] 2) Start the air compressor to flush and roll the cement slurry so that the sediment remaining at the bottom of the hole is mixed with the cement slurry and suspended in the cement slurry.

[0084] 6. Grouting pump full hole replacement grouting

[0085] 1) After the cement slurry hole washing is completed, remove the grouting pipe of the air compressor and install it to the grouting pump interface;

[0086] 2) Grouting starts from one hole, and the sewage, sediment and cement slurry mixture in the hole are replaced out of the hole from the bottom of the hole by cement slurry from other holes. During the replacement process, a dedicated person checks the slurry return situation at the hole mouth, and stops grouting when the properties of the slurry returned from each core hole are consistent with the grouting liquid in the mixing bucket.

[0087] 7. Installation of full-hole hydraulic expansion sealer

[0088] 1) If there are two core holes in the cast-in-place pile treatment, prepare two expansion hole sealers on site;

[0089] 2) One hole is sealed with an expansion hole sealer connected to a grouting pipe, and the other hole is sealed with an expansion hole sealer;

[0090] 8. Grouting pump high pressure sealing grouting

[0091] 1) The grouting pipe is equipped with a stop valve. Open the stop valve first when grouting.

[0092] 2) When the properties of the slurry returning from the orifice are consistent with those in the mixing barrel, close the slurry stop valve and perform high-pressure grouting;

[0093] 3) Connect the grouting pump to the speed regulator and maintain the grouting pressure at about 1.0 MPa. After the grouting is completed, first release the grouting pressure and then release the water pressure of the expansion sealer to avoid slurry spraying. Pull out the grouting pipe and expansion sealer and rinse them immediately.

[0094] 9. Core extraction test three days after grouting

[0095] 1) After grouting and curing for 3 days, on-site core extraction testing can be carried out;

[0096] 2) The extracted core samples were placed neatly, and core samples were cut from the grouting section for compressive strength testing. The strengths met the design requirements.

[0097] Practical application examples

[0098] Bojin Business Plaza "B107-0009 plot" project earthwork, foundation pit support and foundation engineering, project overview:

[0099] The proposed project site is located at No. 1, Tairan 7th Road, Chegongmiao Industrial Zone, Futian District, Shenzhen. The north and south sides of the plot are adjacent to Tairan 8th Road and Binhe Avenue respectively, and the east side is Tairan 7th Road. The total land area of this project is 13,970m2, and the total construction area is approximately 220,000m2. The foundation pit has a circumference of 429m and an excavation depth of 20m. The support form is "underground continuous wall + 3 internal supports". The engineering piles are designed to be bored cast-in-place piles with pile diameters ranging from Φ1000mm to Φ2800mm. The designed pile length is 15m to 32m, with an average pile length of approximately 20m. The pile end penetrates into the slightly weathered granite layer 0.5m to 1.5m.

[0100] Pile bottom sediment defects

[0101] The results of various tests such as small strain and core drilling showed that two main building compression piles had sediment defects. One defective pile had a diameter of 1.2m, an effective pile length of 20.52m, and a sediment thickness of 0.41m at the pile bottom; the other defective pile had a diameter of 1.6m, an effective pile length of 28.6m, and a sediment thickness of 0.38m at the pile bottom.

[0102] Construction and inspection status

[0103] The number of core drilling holes for defective piles with a diameter of 1.2m was 2, and the number of core drilling holes for defective piles with a diameter of 1.6m was 3. The project department adopted a multi-media high-pressure hole washing and high-strength slurry sealing and repair method for the bottom sediment of the cast-in-place piles. The existing core drilling holes were used to wash the bottom sediment of the piles with a multi-media method, and then cement slurry prepared with ultra-fine cement was used for grouting, thus achieving effective defective pile treatment. After three days of maintenance, the second core drilling test was carried out by the Shenzhen Futian District Construction Engineering Quality Inspection Center. The sediment at the bottom of the defective piles was cleaned, the strength of the grouting body met the design requirements, and the piles passed the acceptance inspection.

[0104] 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 in the scope of protection of the present invention.

Claims

1. A multi-media high-pressure hole washing and slurry sealing grouting repair method for cast-in-place pile bottom sediment, characterized in that: The construction steps include: 1) Drill a hole to the bedrock on the cast-in-place pile, remove the core rod by core extraction, and form a core extraction hole on the cast-in-place pile. Place the slotted hole washer in the air compressor into the core extraction hole through a high-pressure pipe, inject clean water into the core extraction hole, start the air compressor to perform high-pressure hole washing, and keep the slotted hole washer lowered synchronously until it reaches the sediment section; Highly compressed air passes through the interior of the high-pressure pipe and enters the slotted hole washer, and then is ejected from the slotted hole washer toward the core-pulling hole, ejecting the sewage in the core-pulling hole outward until the sewage becomes clear water; 2) Pull the high-pressure air pipe and the slotted hole washer out of the core pulling hole, inject cleaning liquid into the core pulling hole and soak it for a set time; place one end of the high-pressure water flow pipe into the core pulling hole, and connect the other end of the high-pressure water flow pipe to the air compressor and the grouting pump through a three-way pipe head, and connect one end of the high-pressure water flow pipe to the open-hole hole washer; start the air compressor and the grouting pump respectively to perform high-pressure air and high-water mixed hole washing, and keep the open-hole hole washer lowered synchronously until the sediment section; The high-pressure water flow passes through the high-pressure water flow pipe and enters the open-hole type hole washer, and then is sprayed from the open-hole type hole washer toward the core pulling hole, spraying out the mud skin, mud blocks and small particles of sediment in the core pulling hole; 3) Remove the high-pressure water flow pipe and the open-hole washer from the core pulling hole, and inject cement slurry into the core pulling hole through the grouting pipe by the grouting pump until the volume of the cement slurry in the core pulling hole reaches a set value; replace the grouting pump with an air compressor, and use the air compressor to deliver high-compressed air from the slotted hole washer into the core pulling hole through the grouting pipe. The high-compressed air fully mixes the cement slurry in the core pulling hole with the small particles of sediment remaining in the core pulling hole, and the mixed cement slurry is ejected from the core pulling hole; 4) Replace the air compressor with a grouting pump, and inject cement slurry into the core pulling hole through the grouting pipe. The cement slurry is ejected from the slotted hole washer toward the core pulling hole until the cement slurry overflowing from the core pulling hole has the same properties as the cement slurry in the mixing tank. 5) The core hole is sealed and grouting is performed using an expansion sealer. The grouting pump injects cement slurry into the core hole through a grouting pipe. The cement slurry is subjected to high pump pressure in a confined space and is then pressed into the fine cracks of the pile body and pile bottom under the action of the high pump pressure until the fine cracks of the pile body and pile bottom are fully filled with cement slurry. In the construction step 2), the air compressor delivers high air pressure to the three-way pipe head through the high air pressure pipe, and the grouting pump delivers high water pressure to the three-way pipe head through the high water pressure pipe. The high air pressure and high water pressure form the high-pressure water flow in the high-pressure water flow pipe; In the construction step 2), the open-hole washer includes a spray pipe, which is provided with a plurality of sidewall holes, and the plurality of sidewall holes are arranged circumferentially and spaced apart along the outer side of the spray pipe; the high-pressure water flow pipe is connected to the core-pulling hole through the sidewall holes; The injection pipe is provided with a wall cleaning ring, which is arranged around the outer circumference of the injection pipe. The injection pipe and the wall cleaning ring are connected through a bearing. The wall cleaning ring is provided with a plurality of wiping strips that are bent and extended toward the inner wall of the core pulling hole. The plurality of wiping strips are arranged around the outer circumference of the wall cleaning ring at intervals; the wiping strip has an inner end face facing the side wall hole and an outer end face away from the side wall hole, and an elastic friction layer is provided on the outer end face, and the friction layer is attached to the inner wall of the core pulling hole; the inner end face has a triangular push block protruding toward the side wall hole, and the triangular push block is arranged relative to the side wall hole, and there is a gap between the two.

2. The multi-media high-pressure hole washing and slurry sealing grouting repair method for cast-in-place pile bottom sediment according to claim 1 is characterized in that: In the construction step 1), the slotted hole washer includes an air jet tube, an exhaust port is provided on the bottom of the air jet tube, and the high-pressure pipe is connected to the core-pulling hole through the exhaust port; a plurality of open slots are provided on the outer side of the air jet tube, and the plurality of open slots are arranged at intervals along the circumference of the outer side of the air jet tube, and the high-pressure pipe is connected to the core-pulling hole through the open slots.

3. The method for repairing cast-in-place pile bottom sediment by multi-media high-pressure hole washing and slurry sealing grouting according to claim 1 or 2, characterized in that: In the construction step 3), the grouting is stopped when the grouting volume of the cement slurry reaches 1 / 3 to 1 / 2 of the volume of the core-drawing hole.

4. The method for repairing cast-in-place pile bottom sediment by multi-media high-pressure hole washing and slurry sealing grouting according to claim 1 or 2, characterized in that: In the construction step 4), the grouting pump is connected to the mixing barrel through a conduit.

5. The method for repairing cast-in-place pile bottom sediment by multi-media high-pressure hole washing and slurry sealing grouting according to claim 1 or 2, characterized in that: In the construction step 5), the expansion sealer includes a sealing tube that is expanded and sealed in the core pulling hole by water injection, and a delivery pipe connected to the sealing tube, and a water pressure pump is connected to the delivery pipe; the sealing tube is arranged circumferentially along the outer periphery of the grouting tube, and the inner side wall of the sealing tube abuts against the outer periphery of the grouting tube.

6. The method for repairing cast-in-place pile bottom sediment by multi-media high-pressure hole washing and slurry sealing grouting according to claim 5, characterized in that: A one-way valve is provided on the delivery pipe, a drainage pipe is provided between the one-way valve and the sealing pipe, the drainage pipe is communicated with the delivery pipe, and a water pressure valve is provided on the drainage pipe.

7. The method for repairing cast-in-place pile bottom sediment by multi-media high-pressure hole washing and slurry sealing grouting according to claim 1 or 2, characterized in that: In the construction step 1), the orifice of the core-pulling hole is inserted into the stopper tube, the bottom of the stopper tube is inserted into the core-pulling hole, and the top of the stopper tube is exposed outside the core-pulling hole.

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