CN110904957A - Construction method of large-diameter high-verticality jet grouting pile in gravel stratum - Google Patents
Construction method of large-diameter high-verticality jet grouting pile in gravel stratum Download PDFInfo
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- CN110904957A CN110904957A CN201911320968.1A CN201911320968A CN110904957A CN 110904957 A CN110904957 A CN 110904957A CN 201911320968 A CN201911320968 A CN 201911320968A CN 110904957 A CN110904957 A CN 110904957A
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D5/00—Bulkheads, piles, or other structural elements specially adapted to foundation engineering
- E02D5/22—Piles
- E02D5/34—Concrete or concrete-like piles cast in position ; Apparatus for making same
- E02D5/46—Concrete or concrete-like piles cast in position ; Apparatus for making same making in situ by forcing bonding agents into gravel fillings or the soil
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D15/00—Handling building or like materials for hydraulic engineering or foundations
- E02D15/02—Handling of bulk concrete specially for foundation or hydraulic engineering purposes
- E02D15/04—Placing concrete in mould-pipes, pile tubes, bore-holes or narrow shafts
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B7/00—Special methods or apparatus for drilling
Abstract
The invention discloses a construction method of a large-diameter high-verticality jet grouting pile in an oval gravel stratum, which comprises the following construction steps: drilling by using a down-the-hole hammer drilling process, loosening peripheral pebbles under the impact action of a hammer head, blowing out debris in the pebble layer around the drill hole, wherein the diameter of the drill hole is 273-800 mm; the full length of the steel casing is followed; pulling out the drill bit and lowering the temporary support tube; pulling out the steel casing, and supporting the hole wall by the temporary supporting tube; putting a high-pressure rotary spraying drill rod to the bottom of the hole, spraying high-pressure cement slurry and high-pressure gas on the side surface of the hole, smashing the temporary supporting tube at the corresponding position into fine fragments, collapsing the loose pebble ring body and falling into the drilling range, cutting and disturbing the collapsed pebbles by the high-pressure cement slurry and the high-pressure gas to further expand the collapsed diameter, and filling cement slurry into pebble gaps; and lifting the rotary spraying drill rod and continuing to perform rotary spraying to the designed height, and forming the large-diameter jet grouting pile after the cement slurry is solidified. The invention can form the large-diameter high-verticality jet pile in the gravel stratum.
Description
Technical Field
The invention relates to the technical field of jet grouting pile construction, in particular to a construction method of a large-diameter high-verticality jet grouting pile in an oval gravel stratum.
Background
The jet grouting method is also called as jet grouting method, is called as jet grouting for short, is called as jet grouting pile for short, is started from the high-pressure jet grouting method in the seventies of the twentieth century, and is comprehensively developed and applied in China in the eight and ninety years. The practice proves that the method has good effects on treating silt, mucky soil, cohesive soil, silt, sandy soil, artificial filling, gravelly soil and the like.
The jet grouting pile is characterized in that a jet grouting pipe and a nozzle drill are arranged at a designed elevation at the bottom of the pile by using a drilling machine, prepared grout in advance is sprayed out from a nozzle at the edge of the grouting pipe at a high speed after obtaining huge energy through a high-pressure generating device to form a stream with highly concentrated energy, a soil body is directly damaged, in the spraying process, a jet grouting drill rod is lifted while rotating, so that the grout and the soil body are fully stirred and mixed, and a columnar solidification body with a certain diameter is formed in the soil, so that a foundation is reinforced.
With the development of the jet grouting pile technology, the jet grouting technology of double pipes and triple pipes is developed on the basis of the original single pipe, and the pile forming diameter is also increased continuously. However, even if the construction is carried out by adopting the triple-tube process with the strongest destructive power to the soil body, the large-diameter pile body cannot be formed in the gravel and pebble stratum. Therefore, a construction process capable of realizing a large-diameter pile body in a gravel and pebble stratum by adopting rotary spraying is required to be developed.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a construction method of a large-diameter high-verticality jet grouting pile in a gravel stratum, which has the advantage that a large-diameter rotary jet pile body can be formed in the gravel and gravel stratum.
The above object of the present invention is achieved by the following technical solutions: the method comprises the following construction steps:
step 1: leading a down-the-hole hammer hole and following a steel casing: drilling by using a down-the-hole hammer drilling process, wherein the diameter of the drilled hole is 273mm-800mm, peripheral pebbles are loosened under the impact action of a hammer head during drilling, and chips in a pebble layer in a certain range around the drilled hole are blown out to form a loose pebble ring body; the steel casing is tracked along the whole length until the hole is drilled to the designed depth; the steel casing isolates the loose pebble ring body outside the drill hole to prevent the drill hole from collapsing;
step 2: pulling out the drill bit and lowering the temporary support tube: pulling out a down-the-hole hammer drill bit and a down-the-hole hammer drill rod in the steel casing, and moving the down-the-hole hammer drilling machine away; placing the temporary supporting tube into the drill hole, wherein the outer diameter of the temporary supporting tube is smaller than the inner diameter of the steel casing;
and step 3: the steel casing is pulled out, and the temporary supporting tube replaces the steel casing to support the hole wall;
and 4, step 4: high-pressure rotary spraying: putting a high-pressure rotary spraying drill rod to the bottom of the hole, spraying high-pressure cement slurry on the side face of the rotary spraying drill rod close to the bottom end of the rotary spraying drill rod, crushing the temporary supporting tube at the corresponding position into fine fragments by the high-pressure cement slurry, collapsing pebbles of a loose pebble ring body at the back of the temporary supporting tube into a drilling range, cutting and disturbing the collapsed pebbles by the high-pressure cement slurry, further collapsing an existing pebble layer outside the loose pebble ring body after being impacted and disturbed by the high-pressure cement slurry, further expanding the collapse diameter, and filling gaps among the collapsed pebbles by the cement slurry;
and 5: lifting the rotary spraying drill rod and continuing high-pressure rotary spraying: in the lifting process, the temporary supporting tube is gradually crushed, pebbles behind the temporary supporting tube gradually collapse until the temporary supporting tube is lifted to the designed height, and after cement grout is solidified, a large-diameter jet grouting pile is formed.
According to the technical scheme, a drill hole with a larger diameter is led out by utilizing a down-the-hole hammer process, peripheral pebbles are loosened under the impact action of the hammer head, meanwhile, high-pressure air blows off stone chips in a pebble layer around the drill hole out of the drill hole, and the hammer head vibrates to loosen the peripheral pebbles and form a gap; as the temporary supporting tube is broken during high-pressure injection, pebbles around the drill hole collapse to form a loose structure with large gaps; the larger the diameter of the drill hole is, the larger the collapse range is, and the larger the gap among the pebbles is, namely the pebbles have larger movement space under the impact of high-pressure cement slurry; and finally, after the collapsed pebble gap is filled with cement slurry, a large-diameter pile body is formed. In addition, as the whole-course steel casing is adopted during hole guiding, hole collapse is avoided on one hand, and on the other hand, the steel casing plays a role in guiding through the rigidity of the steel casing, so that the problem of deflection easily caused when uneven hardness is met is avoided, and the verticality reliability is obviously improved; after the temporary supporting tube is placed, the hole collapse phenomenon which is easy to occur after the steel casing is pulled out is ensured.
The invention is further configured to: the jet from the drill bit at the bottom of the rotary jet drill rod also comprises high-pressure gas, and the high-pressure gas and the high-pressure cement slurry impact the collapsed pebbles together.
Through above-mentioned technical scheme, can increase the effective jet distance of slurry for the diameter that collapses further enlarges, and lets the cobble roll in downthehole better formation, and the clearance is more even, and final pile body is also more even.
The invention is further configured to: the grouting pressure of the cement grout is not less than 35MPa, and the flow rate of the sprayed cement grout is not less than 200L/min.
Through above-mentioned technical scheme, utilize superhigh pressure and super large flow for the very big thick liquid post of energy is formed to the spun grout, thereby carries out better cutting disturbance to the cobble, makes the cobble after collapsing roll, finally forms more even pile body.
The invention is further configured to: in the step 1, a down-the-hole hammer is subjected to process hole leading, the down-the-hole hammer is matched with a high-wind-pressure and high-wind-quantity air compressor, the wind pressure is more than or equal to 3.0MPa, and the wind quantity is more than or equal to 30 cubic meters per minute.
By the technical scheme, high wind pressure and high wind volume can be suitable for drilling holes with the depth of footage being more than or equal to 40 m.
The invention is further configured to: adjusting the verticality of a vertical guide rail before the down-the-hole hammer process hole leading in the step 1; the drilling rod of the first section of down-the-hole hammer is slowly advanced in the drilling process, so that the verticality of the drilling rod and the steel casing is improved; the wall thickness of the steel casing is larger than 10mm, the rigidity of the steel casing is large, the guiding effect is achieved, and the verticality control is facilitated.
By adopting the technical scheme, the perpendicularity of the first section of steel casing is better ensured, so that the perpendicularity of the drilled hole is ensured; the large-diameter steel casing with the thickness larger than 10mm has higher rigidity, and the verticality of the drilled hole is further ensured.
The invention is further configured to: and 4, adopting a high tower frame for high-pressure rotary spraying in the step 4, and enabling a rotary spraying drill rod to stretch into the bottom of the hole at one time to perform high-pressure rotary spraying.
Through the technical scheme, the connecting pipe in the high-pressure rotary spraying process is avoided, the stop interval of rotary spraying is prevented, the continuity and integrity of the rotary-sprayed pile body are ensured, and the pile body has better water stopping performance and stress performance. In addition, joint damage caused by frequent pipe connection and sealing failure caused by high-pressure lower joint damage are avoided, and the spraying effect is influenced.
The invention is further configured to: in the spraying process, the slurry flowing out of the pipe orifice of the temporary supporting pipe is filtered, then returns to the cement slurry stirring pool, is prepared and stirred again, is pressurized by the high-pressure pump and then is sprayed into the drill hole again from the rotary spraying drill rod, and the reutilization is realized.
Through above-mentioned technical scheme, realize cement thick liquid's reuse, avoid the material extravagant, and prevent to pollute, environmental protection more, more economical and practical.
The invention is further configured to: and filtering the slurry flowing out of the pipe orifice by adopting slurry purification equipment.
Through the technical scheme, the mud purification equipment is used for filtering cement paste, so that sand particles above 60 microns can be filtered, cement particles smaller than 60 microns are recovered into the cement paste stirring pool, and the cement particles are sprayed into the drill hole again after the water cement ratio is adjusted again.
The invention is further configured to: a pipe shoe is arranged between the drill bit and the steel casing.
Through the technical scheme, the pipe shoe arranged on the drill bit can drive the steel casing to move downwards synchronously, the hole wall is protected in time, the situation that the steel casing is clamped by the hole wall is avoided, and the drilling efficiency is improved.
The invention is further configured to: and (3) pulling out the steel protecting cylinder by adopting a tube extractor, or pulling up the steel protecting cylinder by adopting the tube extractor for a certain height, and then replacing the tube extractor with a crane to pull out the steel protecting cylinder at one time.
According to the technical scheme, for deeper drilling holes, due to the fact that extrusion force and friction force of the hole wall to the steel casing are large, the steel casing can be smoothly pulled out by adopting the patented hydraulic pipe puller; in addition, the pipe puller is responsible for pulling the steel protective cylinder and is pulled out by the crane at one time, so that the working efficiency is further improved.
The invention is further configured to: the inner wall and/or the outer wall of the temporary support tube are/is provided with a plurality of scratches or the tube wall is provided with a plurality of small holes.
Through above-mentioned technical scheme, be provided with scratch and the interim stay tube of aperture and have had certain intensity to be used for supporting the pore wall, simultaneously easy being broken into little piece by beating, the piece presss from both sides in the pile body, can not influence the integrality of pile body to guarantee better stagnant water nature.
The invention is further configured to: the outer diameter of the temporary supporting tube is 2-7cm smaller than the inner diameter of the steel casing.
Through the technical scheme, on one hand, the temporary supporting tube ensures the large diameter, and ensures that a large slurry outlet exhaust channel is formed between the temporary supporting tube with the large diameter and the rotary spraying drill rod in the high-pressure spraying process, so that the discharge of a large amount of slurry can be better met, and the accidents of arching of structures such as the stratum around the drill hole or the road and the like caused by the blockage of a slurry return channel are avoided; on the other hand, the temporary supporting tube is close to the steel casing as much as possible, so that the extension of the subsequently lowered spray nozzle is as much as possible, and the effective spray range is enlarged.
The invention is further configured to: the diameter of the guniting nozzle of the high-pressure cement grout is 4-6 mm.
Through the technical scheme, the cement slurry column with a large diameter is formed, and the pebbles are well impacted and stirred.
The invention is further configured to: and 4, ejecting the cement slurry sprayed in the high-pressure rotary manner in the horizontal direction or the inclined direction.
Through the technical scheme, the cement paste is selected to select the ejection angle according to different geology and different working conditions, so that the pebble is better cut and disturbed.
The invention is further configured to: the large-diameter jet grouting pile is used for water stop piles among foundation pit slope protection piles, rows of water stop piles behind the slope protection piles and grouting piles which are mutually overlapped to form a water stop curtain, water stop piles at the joint of the underground continuous wall or a stressed wall formed after profile steel is inserted.
According to the technical scheme, the formed pile body comprises pebbles and cement paste to form a concrete-like pile, and the pile is formed uniformly, so that the concrete-like pile has good water stopping and stress bearing performances, and can be suitable for various water stopping structures and stress bearing structures.
The invention is further configured to: and 4, replacing high-pressure rotary spraying with high-pressure swing spraying in the step 5 and the step 4 to form a fan-shaped spraying surface, and finally, overlapping the fan-shaped spraying surface with the slope protection piles or automatically overlapping the fan-shaped spraying surface with the slope protection piles to form a waterproof curtain.
According to the technical scheme, the pile body with the sector-shaped section is formed, and the pile body is better suitable for a water stop pile at the back of a slope protection pile and a water stop pile at the joint of an underground continuous wall and the like; the symmetrical fan-shaped pile bodies are mutually lapped to form a connected waterproof curtain.
The invention is further configured to: and 4, adopting a triple pipe rotary spraying process in the high-pressure rotary spraying in the step 4, smashing the temporary supporting pipe at the corresponding position into fine fragments by using high-pressure water, enabling pebbles of a loose pebble ring body at the back of the PVC pipe to collapse into a drilling range, and under the common cutting disturbance of the high-pressure water and the high pressure, further collapsing after an existing pebble layer outside the loose pebble ring body is subjected to impact disturbance, further expanding the collapse diameter, and filling gaps among the collapsed pebbles with cement slurry.
Through the technical scheme, the triple-pipe rotary spraying process is combined with the large-diameter drilling, and the loose pebble ring body collapses, so that the large-diameter jet grouting pile body is formed.
The invention is further configured to: replacing the high-pressure rotary spraying in the step 4 by: and (2) putting a high-pressure rotary spraying drill rod to the bottom of the hole, spraying high-pressure cement paste, high-pressure water and high-pressure air to the side surface of the rotary spraying drill rod close to the bottom end of the rotary spraying drill rod, smashing the temporary supporting pipe at the corresponding position into fine fragments by the high-pressure water and the high-pressure cement paste, collapsing pebbles of a loose pebble ring body behind the temporary supporting pipe into a drilling range, cutting and disturbing the collapsed pebbles by the high-pressure water, the high-pressure cement paste and the high-pressure air, further collapsing after an existing pebble layer outside the loose pebble ring body is subjected to impact disturbance, so that the collapse diameter is further enlarged, and filling gaps among the collapsed pebbl.
Through the technical scheme, the temporary supporting tube is broken by high-pressure water and the pebbles are impacted, gaps among the pebbles are filled with cement slurry, and finally the pile body is formed.
In conclusion, the invention has the following beneficial effects:
1. leading holes and twice hole collapse are carried out through a large-diameter down-the-hole hammer impact process, so that pebbles form a large gap in a drilled hole, then spraying and stirring are carried out by utilizing ultrahigh-pressure and ultrahigh-energy cement paste, the cement paste and the pebbles are uniformly stirred, and a pile is formed after solidification; the construction method well solves the problems that the existing high-pressure rotary spraying cannot cut or extrude the pebble stratum, and an effective pile body with a large diameter is formed;
2. during hole guiding, the whole steel casing is adopted for follow-up, so that hole collapse is avoided, a guiding effect is achieved, and the verticality reliability is obviously improved; after the temporary supporting tube is placed, the hole collapse phenomenon which is easy to occur after the steel casing is pulled out is ensured;
3. the high tower frame jet drilling machine can jet and form a pile at one time, so that the influence on the jet quality and efficiency caused by frequent connection of a drill rod is avoided;
4. by recycling the cement slurry, the waste of materials is avoided, the pollution is prevented, and the construction method is more economical and applicable, and is more environment-friendly;
5. the collapse range of the pebble bed is further expanded by means of measures such as ultrahigh pressure, a large-diameter nozzle, high-pressure gas and the like, so that a pile body with a larger diameter is formed;
6. the pipe wall of the temporary supporting pipe is provided with the small holes or scratches, so that the temporary supporting pipe is easily broken into small fragments, and the phenomenon that the large fragments affect the quality of the pile body to cause water leakage is prevented;
7. the construction efficiency is improved by adopting the pipe shoe and the special pipe drawing machine.
Drawings
FIG. 1 is a schematic view showing the peripheral pebbles being loosened and chips being blown out of a borehole by high pressure air when a down-the-hole hammer is guided;
FIG. 2 is a schematic diagram of the steel casing drawn out after the temporary support tube is put in;
FIG. 3 is a schematic view of the state in the borehole during high pressure rotary jetting.
Reference numerals: 1. a steel casing; 2. a drill bit; 21. a down-the-hole hammer drill stem; 3. loosening the pebble ring body; 4. supporting the tube temporarily; 5. rotating and spraying a drill rod; 6. grout slip casting pipe.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings. In which like parts are designated by like reference numerals. It should be noted that, as used in the following description, the terms "front," "rear," "left," "right," "upper," "lower," "bottom" and "top" refer to directions in the drawings, and the terms "inner" and "outer" refer to directions toward and away from, respectively, the geometric center of a particular component.
Example 1:
the construction method of the large-diameter high-verticality jet grouting pile in the gravel stratum comprises the following construction steps (because the gravel stratum is similar in structure, the gravel stratum is taken as an example for explanation in the following embodiments):
step 1: leading a down-the-hole hammer hole and a steel casing 1 to follow: as shown in FIG. 1, the hole is drilled by a down-the-hole hammer drilling process, and the diameter of the drilled hole is 273mm-800mm (273 mm is taken as an example in the embodiment).
Before hole guiding, the verticality of a vertical guide rail of a drilling machine is adjusted, the drilling process of the first section of down-the-hole hammer drill rod 21 is slowly advanced, and the verticality of the drill rod and the steel casing 1 is improved. In the drilling process, peripheral pebbles are loosened under the impact action of the hammer head, and meanwhile, scraps in a pebble layer in a certain range around the drill hole are blown out to form a loose pebble ring body 3; the wall thickness of the steel casing 1 is more than 10mm, and the steel casing follows the whole length until the steel casing is drilled to the designed depth; the steel casing 1 isolates the loose pebble ring body 3 outside the drill hole to prevent the drill hole from collapsing;
when the steel protects a section of thick bamboo 1 and receives the friction and can't be automatic under gravity during the manhole, can adopt top hydraulic means to push down steel protects 1 top surface of a section of thick bamboo, the preferred, installation pipe shoe between drill bit 2 and the steel protects a section of thick bamboo 1 for steel protects a section of thick bamboo 1 better overcomes the frictional force of pore wall, in time struts the pore wall.
When the drilling depth is deeper, for example, the hole depth exceeds 40m, the down-the-hole hammer is matched with a high-wind-pressure and high-wind-volume air compressor, the wind pressure is more than or equal to 3.0MPa, and the wind volume is more than or equal to 30 cubic meters per minute.
Step 2: the drill bit 2 is pulled out, and the temporary support tube 4 is lowered: as shown in fig. 2, the down-the-hole hammer drill bit 2 and the down-the-hole hammer drill rod 21 in the steel casing 1 are pulled out, and the down-the-hole hammer drilling machine is removed; the temporary support tube 4 is lowered section by using a crane or other machinery or manpower. The temporary support tube 4 can be a thin-wall tube or a perforated tube with a plurality of small holes, or a tube with annular or latticed scratches arranged on the tube wall, and the material can be a PVC tube or other tubes with certain strength and capable of being crushed by high-pressure cement slurry. The diameter of the temporary supporting tube 4 is 2-7cm smaller than the inner diameter of the steel casing 1. When a pipe shoe is not arranged between the drill bit 2 and the steel casing 1, the diameter of the temporary supporting pipe 4 is smaller than the inner diameter of the steel casing 1 by 2-4 cm; when the pipe boot is installed, the inner diameter of the pipe boot is about 2cm smaller than that of the steel casing 1, and the pipe boot is installed at the bottom end of the steel casing 1 and can only be pulled out along with the steel casing 1, so that the inner diameter of the temporary supporting pipe 4 is smaller than the inner diameter of the steel casing 1 by 4-7cm, and the steel casing 1 can be pulled out conveniently. In this example, since the pipe shoe is mounted, a PVC pipe having a diameter of 200mm is used.
And step 3: pulling out the steel pile casing 1: the steel casing 1 is pulled out by a crane and other machinery; preferably, a hydraulic pipe extractor is adopted to extract the steel casing 1, or after the pipe extractor is adopted to extract the steel casing 1 for a certain height, a crane is used to extract the steel casing 1 for one time.
And 4, step 4: high-pressure rotary spraying: as shown in fig. 3, the high-pressure rotary spraying drill rod 5 is lowered, and the rotary spraying drill rod 5 is extended into the bottom of the hole at one time by using a high drill stand of a machine such as a long spiral drilling machine, so as to perform high-pressure rotary spraying. The side surface of the rotary spraying drill rod 5 close to the bottom end of the rotary spraying drill rod 5 is provided with a cement paste spraying nozzle and a high-pressure gas spraying nozzle, a cement paste grouting pipe 6 and a high-pressure gas pipe are arranged in the rotary spraying drill rod 5, high-pressure cement paste is horizontally or obliquely ejected from the cement paste spraying nozzle to smash the temporary support pipe 4 at the corresponding position into fragments smaller than 2cm, pebbles of the loose pebble ring body 3 behind the temporary support pipe 4 collapse into a 273 phi drilling range, the high-pressure cement paste and the high-pressure gas cut and disturb the collapsed pebbles, an existing pebble layer outside the loose pebble ring body 3 is further collapsed after being impacted and disturbed, the collapse diameter is further enlarged, and cement paste fills gaps among the collapsed pebbles.
And selecting the angle of the cement paste to be ejected according to different geology and different working conditions. For example, when the proportion of large-particle pebbles in the pebble bed is large, the high-pressure cement slurry ejected horizontally rebounds, and at the moment, the slurry is sprayed obliquely upwards, so that the influence radius of the high-pressure cement slurry is further enlarged due to the upward moving space of the large-particle pebbles. For another example, when the pile bottom is designed to be overlapped with bedrock to form a waterproof curtain, because the position of the nozzle is slightly away from the bottom of the hole, the cement paste can be better overlapped with the bedrock by adopting the inclined downward spraying, so that the joint surface of the pebble bed and the bedrock forms a continuous pile body, and the condition that the pile bottom is not embedded into the bedrock is avoided.
The air nozzle of the high-pressure air can be positioned on the pipe wall of the rotary spraying drill rod 5, positioned above or below the high-pressure guniting nozzle, and also concentrically arranged with the guniting nozzle, so that impact of high-pressure air-coated guniting is formed, and the air nozzle can also be positioned at the bottom end of the rotary spraying drill rod 5 and arranged downwards. The high-pressure gas and the high-pressure cement slurry act together, so that the collapse diameter is further enlarged, pebbles are better formed and rolled in the hole, and the gap is more uniform.
The following relevant parameters are preferably selected in the high-pressure rotary spraying process: the diameter of the guniting nozzle is 4-6mm, preferably 5 mm; the grouting pressure of the cement grout is not less than 35MPa, and the flow rate of the sprayed cement grout is not less than 200L/min; the pressure of the high-pressure gas is 1.0-1.8 MPa.
In the spraying process, high-pressure gas carries a large amount of slurry to flow out from the pipe orifice of the PVC pipe, the PVC pipe which is not damaged and is above the slurry spraying position ensures the smoothness of the slurry outlet channel, and accidents caused by the blockage of the slurry outlet channel due to collapse are avoided. Meanwhile, a large slurry outlet channel is formed between the PVC pipe with the large diameter and the rotary spraying drill rod 5, so that the discharge of high-pressure gas and a large amount of slurry can be better met.
During the spraying process, the slurry flowing out of the pipe orifice of the PVC pipe comprises cement paste, pebble chips, soil and the like; the slurry can be filtered, useful cement slurry components are returned to a cement slurry stirring pool for reconstitution and stirring, and then the slurry is pressurized by a high-pressure pump and sprayed into the drill hole again from the rotary spraying drill rod 5, so that the reuse is realized. Slurry purification equipment can be used for filtering the slurry.
Because the energy of the sprayed slurry can be reduced by the slurry in the hole during the rotary spraying and grouting, the slurry spraying nozzle is as close to the temporary support tube 4 as possible, and the distance between the slurry spraying nozzle and the temporary support tube is 20-50mm, so that the impact energy is better utilized, and the influence diameter range is larger. Specifically, the outer diameter of the end part of the jet grouting drill rod 5 is enlarged to be close to the inner wall of the temporary support pipe 4, but other parts of the jet grouting drill rod 5 are not subjected to thickening treatment, so that a slurry discharge channel with a larger size is ensured. Since the jet grouting drill pipe 5 does not need to be drilled, the diameter of the jet grouting drill pipe 5 can be set smaller, thereby ensuring a large-size slurry discharge passage.
And 5: lifting the rotary spraying drill rod 5 and continuing high-pressure rotary spraying: in the lifting process, the temporary supporting tube 4 is gradually crushed, pebbles behind the temporary supporting tube 4 gradually collapse until the temporary supporting tube is lifted to the design height, the jet grouting drill rod 5 is completely pulled out of a drill hole, and after slurry in the drill hole is solidified, a large-diameter jet grouting pile is formed. The lifting speed of the rotary spraying drill rod 5 can be 5-15 cm/min.
The principle of the construction process is as follows: firstly, leading out a drill hole with a larger diameter by using a down-the-hole hammer drilling machine, loosening surrounding pebbles under the vibration action of a hammer head, and blowing stone chips in a pebble layer around the drill hole out of the drill hole by high-pressure air to form a gap by the pebbles around the drill hole; when the high-pressure rotary spraying is carried out, pebbles around the drill hole collapse along with the crushing of the PVC pipe, and a loose structure with large gaps is formed. The larger the diameter of the drill hole is, the larger the collapse range is, and the larger the gap between the pebbles is, namely the pebbles have larger movement space under the impact action of high-pressure cement slurry and high-pressure gas. Under the impact of a fan-shaped slurry column with the nozzle diameter of 5mm and under the condition that the pebbles have larger moving space, the slurry column with ultrahigh energy can impact the range which is not influenced by the down-the-hole hammer, so that the original pebbles in a certain range except the loose pebble ring body 3 collapse, and the pile diameter is further enlarged; in the collapse range, the pebbles and the chippings are continuously rolled and uniformly stirred under the combined action of the high-pressure cement paste and the high-pressure gas, and the cement paste fills gaps to form a complete large-diameter pile body. The whole pile forming process is simple and comprises the following steps: and forming a large gap in the pebbles in the drill hole through the large-diameter guide hole and the two-time hole collapse, spraying and stirring by using high-pressure slurry, uniformly stirring the cement slurry and the pebbles, and forming a pile after solidification. The construction method well solves the problems that the existing high-pressure rotary spraying cannot cut or extrude the pebble stratum, and forms an effective pile body with a large diameter. The rigidity of the steel casing 1 plays a role in guiding, so that the problem of deflection easily caused by uneven hardness is avoided, and the perpendicularity of the pile body is improved.
The formed large-diameter jet grouting pile can play the roles of supporting, water stopping and the like. The waterproof piles can be used as waterproof piles among foundation pit slope protection piles, rows of waterproof piles and grouting piles behind the slope protection piles, and the waterproof piles are mutually overlapped to form waterproof curtains or waterproof piles at joints of underground continuous walls, and the profile steel can also be inserted to form stress walls.
In the embodiment, the diameter of the lead hole is 273mm, the thickness of the loose pebble ring body 3 can reach 5-15cm, the effective aperture after the first hole collapse can reach 373mm-523mm, and the effective pile diameter can reach 700-1150mm after the secondary hole collapse after the high-pressure cement slurry cutting disturbance is added.
Example 2: the differences from example 1 are: the diameter of the guide hole is 500mm, the diameter of the PVC pipe is 460mm, the diameter of the bottom end of the jet grouting drill rod 5 is 420, and the effective diameter of the final pile is larger than 1 m. When the diameter of the pilot hole is 800mm, the effective pile diameter can reach more than 1.3 m.
Example 3:
the differences from example 1 are: and 4, replacing high-pressure rotary spraying with high-pressure swing spraying in the step 5 and the step 4 to form a fan-shaped spraying surface, and finally, overlapping the fan-shaped spraying surface with the slope protection piles or automatically overlapping the fan-shaped spraying surface with the slope protection piles to form a waterproof curtain.
Example 4:
the difference from example 1 is that: the high-pressure rotary spraying in the step 4 adopts a triple pipe rotary spraying process, the temporary supporting pipe 4 at the corresponding position is smashed into fine fragments by high-pressure water, pebbles of the loose pebble ring body 3 at the back of the PVC pipe collapse into a drilling range, under the common cutting disturbance of the high-pressure water and the high pressure, an existing pebble layer outside the loose pebble ring body 3 is further collapsed after being impacted and disturbed, the collapse diameter is further expanded, and cement slurry fills gaps among the collapsed pebbles.
Example 5:
the difference from example 1 is that: replacing the high-pressure rotary spraying in the step 4 by: and (2) putting a high-pressure rotary spraying drill rod to the bottom of the hole, spraying high-pressure cement paste, high-pressure water and high-pressure air to the side surface of the rotary spraying drill rod close to the bottom end of the rotary spraying drill rod, smashing the temporary supporting pipe at the corresponding position into fine fragments by the high-pressure water and the high-pressure cement paste, collapsing pebbles of a loose pebble ring body behind the temporary supporting pipe into a drilling range, cutting and disturbing the collapsed pebbles by the high-pressure water, the high-pressure cement paste and the high-pressure air, further collapsing after an existing pebble layer outside the loose pebble ring body is subjected to impact disturbance, so that the collapse diameter is further enlarged, and filling gaps among the collapsed pebbl. Wherein the pressure of the high-pressure water is preferably equal to or more than 30 MPa.
The present embodiment is only for explaining the present invention, and it is not limited to the present invention, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present invention.
Claims (18)
1. A construction method of a large-diameter high-verticality jet grouting pile in an oval gravel stratum is characterized by comprising the following steps of: the method comprises the following construction steps:
step 1: leading a down-the-hole hammer hole and a steel casing (1) to follow up: drilling by using a down-the-hole hammer drilling process, wherein the diameter of the drilled hole is 273mm-800mm, peripheral pebbles are loosened under the impact action of a hammer head during drilling, and scraps in a pebble layer in a certain range around the drilled hole are blown out to form a loose pebble ring body (3); the steel casing (1) follows along the whole length until the hole is drilled to the designed depth; the steel casing (1) isolates the loose pebble ring body (3) outside the drill hole to prevent the drill hole from collapsing;
step 2: pulling out the drill bit (2) and putting down the temporary support tube (4): pulling out the down-the-hole hammer drill bit (2) and the down-the-hole hammer drill rod (21) in the steel casing (1), and moving away the down-the-hole hammer drilling machine; putting the temporary support tube (4) into the drill hole, wherein the outer diameter of the temporary support tube (4) is smaller than the inner diameter of the steel casing (1);
and step 3: the steel casing (1) is pulled out, and the temporary supporting tube (4) replaces the steel casing (1) to support the hole wall;
and 4, step 4: high-pressure rotary spraying: putting a high-pressure rotary spraying drill rod (5) to the bottom of a hole, spraying high-pressure cement slurry on the side surface of the rotary spraying drill rod (5) close to the bottom end of the rotary spraying drill rod (5), smashing the temporary supporting tube (4) at the corresponding position into fine fragments by the high-pressure cement slurry, collapsing pebbles of a loose pebble ring body (3) at the back of the temporary supporting tube (4) into a drilling range, cutting and disturbing the collapsed pebbles by the high-pressure cement slurry, further collapsing an existing pebble layer except the loose pebble ring body (3) after the impact disturbance of the high-pressure cement slurry, further expanding the collapse diameter, and filling gaps among the collapsed pebbles by the cement slurry;
and 5: lifting the rotary spraying drill rod (5) and continuing high-pressure rotary spraying: in the lifting process, the temporary supporting tube (4) is gradually crushed, pebbles behind the temporary supporting tube (4) gradually collapse until the temporary supporting tube is lifted to the designed height, and after cement grout is solidified, a large-diameter jet grouting pile is formed.
2. The construction method of the large-diameter high-verticality jet grouting pile in the gravel-egg stratum as claimed in claim 1, which is characterized in that: the gas sprayed out from the bottom end of the rotary spraying drill rod (5) also comprises high-pressure gas, and the high-pressure gas and the high-pressure cement slurry impact the collapsed pebbles together.
3. The construction method of the large-diameter high-verticality jet grouting pile in the gravel-egg stratum as claimed in claim 1, which is characterized in that: the grouting pressure of the cement grout is not less than 35MPa, and the flow rate of the sprayed cement grout is not less than 200L/min.
4. The construction method of the large-diameter high-verticality jet grouting pile in the gravel-egg stratum as claimed in claim 1, which is characterized in that: in the step 1, the down-the-hole hammer is used for hole leading, the down-the-hole hammer is matched with a high-wind-pressure and high-wind-quantity air compressor, the wind pressure is more than or equal to 3.0MPa, and the wind quantity is more than or equal to 30 cubic meters per minute.
5. The construction method of the large-diameter high-verticality jet grouting pile in the gravel-egg stratum as claimed in claim 1, which is characterized in that: adjusting the verticality of a vertical guide rail before the down-the-hole hammer process hole leading in the step 1; the drilling process of the first section of the down-the-hole hammer drill rod (21) is slowly advanced, so that the verticality of the drill rod and the steel casing (1) is improved; the wall thickness of the steel casing (1) is larger than 10mm, the rigidity of the steel casing (1) is larger, the guiding effect is achieved, and the verticality control is facilitated.
6. The construction method of the large-diameter high-verticality jet grouting pile in the gravel-egg stratum as claimed in claim 1, which is characterized in that: and 4, adopting a high tower frame for high-pressure rotary spraying in the step 4, and extending a rotary spraying drill rod (5) into the bottom of the hole for one time to perform high-pressure rotary spraying.
7. The construction method of the large-diameter high-verticality jet grouting pile in the gravel-egg stratum as claimed in claim 1, which is characterized in that: in the spraying process, slurry flowing out of the pipe orifice of the temporary supporting pipe (4) is filtered, then returns to the cement slurry stirring pool, is prepared and stirred again, is pressurized by a high-pressure pump and then is sprayed into the drill hole again from the rotary spraying drill rod (5), and the reutilization is realized.
8. The construction method of the large-diameter high-verticality jet grouting pile in the gravel-egg stratum as claimed in claim 7, which is characterized in that: and filtering the slurry flowing out of the pipe orifice by adopting slurry purification equipment.
9. The construction method of the large-diameter high-verticality jet grouting pile in the gravel-egg stratum as claimed in claim 1, which is characterized in that: a pipe shoe is arranged between the drill bit (2) and the steel casing (1).
10. The construction method of the large-diameter high-verticality jet grouting pile in the gravel-egg stratum as claimed in claim 1, which is characterized in that: the steel protecting cylinder (1) is pulled out by a pipe puller, or the steel protecting cylinder (1) is pulled up by a pipe puller for a section of height and then replaced by a crane to pull out the steel protecting cylinder (1) once.
11. The construction method of the large-diameter high-verticality jet grouting pile in the gravel-egg stratum as claimed in claim 1, which is characterized in that: the inner wall and/or the outer wall of the temporary support tube (4) is/are provided with a plurality of scratches or the tube wall is provided with a plurality of small holes.
12. The construction method of the large-diameter high-verticality jet grouting pile in the gravel-egg stratum as claimed in claim 1, which is characterized in that: the outer diameter of the temporary supporting tube (4) is 2-7cm smaller than the inner diameter of the steel casing (1).
13. The construction method of the large-diameter high-verticality jet grouting pile in the gravel-egg stratum as claimed in claim 1, which is characterized in that: the diameter of the guniting nozzle of the high-pressure cement grout is 4-6 mm.
14. The construction method of the large-diameter high-verticality jet grouting pile in the gravel-egg stratum as claimed in claim 1, which is characterized in that: and 4, ejecting the cement slurry sprayed in the high-pressure rotary manner in the horizontal direction or the inclined direction.
15. The construction method of the large-diameter high-verticality jet grouting pile in the gravel-egg stratum according to any one of claims 1 to 14, which is characterized in that: the large-diameter high-verticality jet grouting pile is used for water stop piles among foundation pit slope protection piles, row water stop piles behind the slope protection piles and grouting piles which are mutually overlapped to form a water stop curtain, water stop piles at the joint of an underground continuous wall or a stress wall formed by inserting section steel.
16. The construction method of the large-diameter high-verticality jet grouting pile in the gravel-egg stratum according to any one of claims 1 to 14, which is characterized in that: and 4, replacing high-pressure rotary spraying with high-pressure swing spraying in the step 5 and the step 4 to form a fan-shaped spraying surface, and finally, overlapping the fan-shaped spraying surface with the slope protection piles or automatically overlapping the fan-shaped spraying surface with the slope protection piles to form a waterproof curtain.
17. The construction method of the large-diameter high-verticality jet grouting pile in the gravel-egg stratum according to any one of claims 1 to 12, which is characterized in that: the high-pressure rotary spraying in the step 4 adopts a triple pipe rotary spraying process, the temporary supporting pipe (4) at the corresponding position is smashed into fine fragments by high-pressure water, pebbles of the loose pebble ring body (3) at the back of the PVC pipe collapse to fall into a drilling range, under the common cutting disturbance of high-pressure water and high air pressure, an existing pebble layer outside the loose pebble ring body (3) is further collapsed after being impacted and disturbed, the collapse diameter is further enlarged, and cement slurry fills gaps among the collapsed pebbles.
18. The construction method of the large-diameter high-verticality jet grouting pile in the gravel-egg stratum according to any one of claims 1 to 14, which is characterized in that: replacing the high-pressure rotary spraying in the step 4 by: the high-pressure rotary spraying drill rod (5) is placed to the bottom of a hole, high-pressure cement slurry, high-pressure water and high-pressure air are sprayed out of the side face of the rotary spraying drill rod (5) close to the bottom end of the rotary spraying drill rod (5), the high-pressure water and the high-pressure cement slurry crush the temporary supporting tube (4) at the corresponding position into fine fragments, pebbles of the loose pebble ring body (3) behind the temporary supporting tube (4) collapse and fall into a drilling range, the high-pressure water, the high-pressure cement slurry and the high-pressure air cut and disturb the collapsed pebbles, and an existing pebble layer outside the loose pebble ring body (3) is further collapsed after being disturbed by impact, so that the collapse diameter is further enlarged, and the cement slurry fills gaps among the.
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| CN2019106782950 | 2019-07-25 | ||
| CN201910678295.0A CN110424385A (en) | 2019-07-25 | 2019-07-25 | The construction of major diameter high verticality jet grouting stake in ovum rubble stratum |
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| CN201910678295.0A Pending CN110424385A (en) | 2019-07-25 | 2019-07-25 | The construction of major diameter high verticality jet grouting stake in ovum rubble stratum |
| CN201911320968.1A Pending CN110904957A (en) | 2019-07-25 | 2019-12-19 | Construction method of large-diameter high-verticality jet grouting pile in gravel stratum |
| CN201911320979.XA Pending CN110984142A (en) | 2019-07-25 | 2019-12-19 | Waste slurry recycling and circulating system for rotary spraying pile or stirring spraying pile |
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| CN111733851A (en) * | 2020-07-02 | 2020-10-02 | 中国建筑第八工程局有限公司 | Construction method for jet grouting waterproof curtain under water-rich sandy gravel geological condition |
| CN112343504A (en) * | 2020-10-23 | 2021-02-09 | 北京中润宝成工程技术有限公司 | Ultrahigh-pressure jet grouting drilling machine and application thereof in jet grouting pile forming method |
| CN114875901A (en) * | 2022-04-13 | 2022-08-09 | 苏坤建设(江苏)有限公司 | Construction method of long spiral drilling and grouting pile |
| CN115652964A (en) * | 2022-12-07 | 2023-01-31 | 福建省地质工程勘察院 | Cobble layer wet drilling construction process and equipment |
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| CN111022070A (en) * | 2020-01-17 | 2020-04-17 | 葛加君 | High-pressure water-spraying tunneling construction method |
| CN112281826B (en) * | 2020-10-23 | 2021-11-09 | 北京中润宝成工程技术有限公司 | Construction method for forming pile by rotary spraying in ovoid gravel stratum |
| CN113718757A (en) * | 2021-08-28 | 2021-11-30 | 中铁时代建筑设计院有限公司 | Bottom expanding device and method based on cast-in-place large-diameter tubular pile |
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| CN114875901A (en) * | 2022-04-13 | 2022-08-09 | 苏坤建设(江苏)有限公司 | Construction method of long spiral drilling and grouting pile |
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| CN110984142A (en) | 2020-04-10 |
| CN110424385A (en) | 2019-11-08 |
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