CN112281933A - Construction method of high-pressure jet grouting pile test - Google Patents
Construction method of high-pressure jet grouting pile test Download PDFInfo
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- CN112281933A CN112281933A CN202011115873.9A CN202011115873A CN112281933A CN 112281933 A CN112281933 A CN 112281933A CN 202011115873 A CN202011115873 A CN 202011115873A CN 112281933 A CN112281933 A CN 112281933A
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- 238000010276 construction Methods 0.000 title claims abstract description 103
- 238000012360 testing method Methods 0.000 title claims abstract description 45
- 239000004568 cement Substances 0.000 claims abstract description 126
- 238000005507 spraying Methods 0.000 claims abstract description 118
- 238000005553 drilling Methods 0.000 claims abstract description 73
- 238000002360 preparation method Methods 0.000 claims abstract description 11
- 239000002002 slurry Substances 0.000 claims description 171
- 238000000034 method Methods 0.000 claims description 76
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 52
- 238000001914 filtration Methods 0.000 claims description 48
- 230000000740 bleeding effect Effects 0.000 claims description 29
- 238000002347 injection Methods 0.000 claims description 26
- 239000007924 injection Substances 0.000 claims description 26
- 239000000203 mixture Substances 0.000 claims description 25
- 238000002156 mixing Methods 0.000 claims description 21
- 239000002689 soil Substances 0.000 claims description 20
- 239000011440 grout Substances 0.000 claims description 19
- 235000017166 Bambusa arundinacea Nutrition 0.000 claims description 10
- 235000017491 Bambusa tulda Nutrition 0.000 claims description 10
- 241001330002 Bambuseae Species 0.000 claims description 10
- 235000015334 Phyllostachys viridis Nutrition 0.000 claims description 10
- 239000011425 bamboo Substances 0.000 claims description 10
- 238000005406 washing Methods 0.000 claims description 9
- 238000004891 communication Methods 0.000 claims description 8
- 229910000831 Steel Inorganic materials 0.000 claims description 5
- 238000006073 displacement reaction Methods 0.000 claims description 5
- 238000002474 experimental method Methods 0.000 claims description 5
- 239000010959 steel Substances 0.000 claims description 5
- 238000003756 stirring Methods 0.000 claims description 5
- 238000011049 filling Methods 0.000 claims description 4
- 238000005086 pumping Methods 0.000 claims description 4
- 238000007789 sealing Methods 0.000 claims description 3
- 238000010408 sweeping Methods 0.000 claims description 3
- 238000009412 basement excavation Methods 0.000 claims description 2
- 238000007689 inspection Methods 0.000 claims description 2
- 238000004062 sedimentation Methods 0.000 claims description 2
- 239000010865 sewage Substances 0.000 claims description 2
- 239000002699 waste material Substances 0.000 claims description 2
- 230000002787 reinforcement Effects 0.000 abstract description 8
- 238000011010 flushing procedure Methods 0.000 abstract description 3
- 238000013461 design Methods 0.000 description 7
- 239000000463 material Substances 0.000 description 4
- 238000012216 screening Methods 0.000 description 4
- 238000005259 measurement Methods 0.000 description 3
- 238000012544 monitoring process Methods 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- 238000011160 research Methods 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- 230000002159 abnormal effect Effects 0.000 description 2
- 239000000654 additive Substances 0.000 description 2
- 239000003245 coal Substances 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000003825 pressing Methods 0.000 description 2
- 230000003014 reinforcing effect Effects 0.000 description 2
- 239000011435 rock Substances 0.000 description 2
- 239000004576 sand Substances 0.000 description 2
- 239000004575 stone Substances 0.000 description 2
- 238000005728 strengthening Methods 0.000 description 2
- 239000011398 Portland cement Substances 0.000 description 1
- 239000004744 fabric Substances 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000012779 reinforcing material Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D33/00—Testing foundations or foundation structures
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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
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B7/00—Special methods or apparatus for drilling
- E21B7/04—Directional drilling
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- Physics & Mathematics (AREA)
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Abstract
The invention relates to the technical field of constructional engineering, and discloses a construction method for a high-pressure jet grouting pile test, which is used for determining relevant parameters of pile forming construction according to a test pile construction result, improving the construction efficiency and ensuring the smooth reinforcement of the ground surface of a tunnel. The construction method of the high-pressure jet grouting pile test comprises the following steps: step one, construction preparation; step two, pile position lofting; thirdly, positioning a drilling machine and preparing for drilling; drilling; step five, preparing cement paste; sixthly, performing rotary spraying operation; step seven, dismantling the drill rod; and step eight, flushing and moving the drilling machine.
Description
Technical Field
The invention relates to the technical field of constructional engineering, in particular to a construction method for testing a high-pressure jet grouting pile.
Background
The high pressure rotary jet grouting method is one of foundation treating methods and has the principle that after a grouting pipe with a nozzle is drilled into a preset position of a soil layer by a drilling machine, a jet flow is formed by high pressure equipment to impact and damage the soil body. When the energy is large, the speed is high and the dynamic pressure in a pulse shape exceeds the structural strength of the soil body, the soil particles are peeled off from the soil body. The damaged part of fine soil particles are blown out of the water surface along with the slurry, the rest of soil particles are stirred and mixed with the slurry under the action of the impact force of a jet flow, centrifugal force, gravity and the like, and are regularly rearranged according to a certain slurry-soil proportion and mass, and after the slurry is solidified, a solidified body is formed in the soil. However, the traditional surface grouting reinforcement method is greatly limited by geological conditions, the construction cost is high, and the construction efficiency is low.
Disclosure of Invention
According to the construction method of the high-pressure jet grouting pile test, the relevant parameters of pile forming construction are determined according to the test pile construction result, the construction efficiency is improved, and the smooth reinforcement of the tunnel ground surface is ensured.
The invention provides a construction method of a high-pressure jet grouting pile test, which comprises the following steps:
step one, construction preparation: carrying out geological exploration, knowing the structural conditions of pipelines, buildings, structures and other public facilities near the engineering, carrying out relocation and reconstruction on the pipelines needing relocation and reconstruction, and completing electrification, access, water communication and land leveling of a construction site;
step two, pile position lofting: measuring the construction axis of the high-pressure jet grouting pile by using a total station, performing repeated test, confirming that the construction axis is qualified, laying pile positions by using a steel ruler and a measuring line, and nailing the pile positions tightly by using bamboo sticks, wherein each pile position corresponds to one bamboo stick, so that the center displacement deviation of a pile hole is smaller than 20 mm;
step three, positioning and drilling preparation of a drilling machine: the method comprises the steps that a drilling machine is in place, leveling and centering treatment are carried out on a pile machine, so that the deviation between a drill rod and a pile position is not more than 5cm, an air compressor and a slurry pump are debugged, the air compressor and the slurry pump are confirmed to be normally operated, the length of the drill rod is checked, a depth line is marked beside a drilling tower, the elevation of the bottom of a hole meets the preset depth, a low-pressure water jetting experiment is carried out, and whether a nozzle and pressure are;
step four, drilling: starting a drilling machine to drill, drilling according to a preset opening caliber, a final hole caliber and a drilling depth, and measuring the hole slope, wherein the opening caliber is not more than 10cm of the outer diameter of the injection pipe, the final hole caliber is more than 2cm of the outer diameter of the injection pipe, the final hole depth is more than 0.5-1.0m of the preset opening depth, and the hole slope is not more than 0.5%;
step five, preparing cement paste: mixing water and cement according to a preset water-cement ratio, uniformly stirring by using a stirrer to obtain a mixture, performing primary filtration treatment and secondary filtration treatment on the mixture to obtain target filtered slurry, measuring the water-cement ratio of the target filtered slurry, and performing pressurization treatment by using a high-pressure pump to generate cement slurry;
step six, jet grouting operation: when the double-grouting pipe reaches a preset depth, conveying the cement paste and compressed air to a nozzle of the double-grouting pipe, rotating the drill rod and the nozzle, performing spraying operation from bottom to top, spraying the cement paste from an inner nozzle at a pressure of more than 20MPa, spraying the compressed air from an outer nozzle at a pressure of more than 0.7MPa, and observing the slurry outflow condition in the rotary spraying process;
step seven, dismantling the drill rod: stopping grouting when the first drill rod exceeds the ground, quickly removing the drill rod after the pressure is reduced, and performing low-pressure supplementary spraying on the top of the rotary spraying pile for 1-2m when the first drill rod rises to a preset elevation of the pile top;
step eight, washing and moving the drilling machine: and after the low-pressure supplementary spraying is finished, washing the drill rod and the nozzle, moving the drilling machine, and performing operation of the next pile position until all the pile positions are constructed.
Optionally, in a first implementation manner of the present invention, the mixing water and cement according to a preset water-cement ratio, uniformly stirring by using a stirrer to obtain a mixture, performing primary filtration and secondary filtration on the mixture to obtain a target filtered slurry, measuring the water-cement ratio of the target filtered slurry, and performing high-pressure pump pressurization to generate the cement slurry includes: adding water into a barrel, adding qualified P.O42.5 cement, and uniformly mixing in a stirrer according to a preset water cement ratio to obtain a mixture, wherein the P.O42.5 cement is ordinary cement with the cement strength of 42.5, and the water cement ratio is 1-1.5; performing primary filtration treatment on the mixture to obtain intermediate filtered slurry and flowing the intermediate filtered slurry into a slurry pool, wherein the primary filtration treatment comprises the step of filtering the mixture through a filter screen; performing secondary filtration treatment on the intermediate filtered slurry to obtain target filtered slurry, wherein the secondary filtration treatment comprises pumping the intermediate filtered slurry into a filter sieve through a slurry pump for secondary filtration; and measuring the water-cement ratio of the target filtering slurry, pressurizing the target filtering slurry by a high-pressure pump to generate cement slurry, and conveying the cement slurry to a drilling machine for rotary spraying through a high-pressure pipe.
Optionally, in a second implementation manner of the present invention, before the mixing water and cement according to the preset water-cement ratio, the method further includes: calculating unit pulp amount, wherein the unit pulp amount is the pulp amount sprayed in unit time, and the calculation formula is as follows: q ═ Q · (1+ β) (H/v) ·; wherein Q is the pulp amount and the unit is m3H is the rotary spraying length in m, q is the spraying amount in m3B is loss coefficient, the range is 0.1-0.2, v is lifting speed, and the unit is m/min; and calculating the total slurry amount according to the unit slurry amount and the jet duration time, and determining the cement amount.
Optionally, in a third implementation manner of the present invention, when the double-grouting pipe reaches a preset depth, the cement slurry and compressed air are delivered to a nozzle of the double-grouting pipe, the drill rod and the nozzle rotate and lift from bottom to top to perform a spraying operation, the cement slurry is sprayed out from an inner nozzle at a pressure greater than 20MPa, and the compressed air is sprayed out from an outer nozzle at a pressure greater than 0.7MPa, and observing a slurry outflow condition in a rotary spraying process includes: when the double grouting pipe reaches the preset depth and the nozzle reaches the preset elevation, performing jet grouting; conveying the cement paste and compressed air to a nozzle of the double-grouting pipe, wherein the flow rate of the cement paste is more than 30L/min, the nozzle rotates and is lifted from bottom to top to perform spraying operation, the rotary spraying lifting speed is 10-15cm/min, the cement paste is sprayed out from an inner nozzle at the pressure of more than 20MPa, and the compressed air is sprayed out from an outer nozzle at the pressure of more than 0.7 MPa; when the spraying is interrupted in the spraying process, carrying out repeated spraying and lapping according to the interruption condition; when slurry leakage occurs in the holes in the spraying process, measures are taken according to the slurry leakage degree; observing the slurry bleeding condition in the rotary spraying process, ensuring that the slurry bleeding amount is less than 20% of the grouting amount, and finding out the reason and taking corresponding measures when the slurry bleeding amount is more than 20% of the grouting amount or the slurry is not bled.
Optionally, in a fourth implementation manner of the present invention, if the injection is interrupted during the injection process, performing the repeated injection overlapping according to the interruption condition includes: when the injection pipe is disassembled in the injection process, the repeated injection is carried out after the injection is recovered, and the lap joint length is not less than 0.1 m; when the spraying process is interrupted due to reasons, the repeated spraying is carried out after the spraying is resumed, and the lap joint length is not less than 0.5 m; when the jet interruption exceeds the initial setting time of the slurry, hole sweeping is carried out, after jet is resumed, re-jet is carried out, and the lap joint length is not less than 1 m.
Optionally, in a fifth implementation manner of the present invention, if slurry leaks from inside the hole during the spraying process, taking measures according to the slurry leakage degree includes: when slurry leaks from the hole in the jetting process, the drill rod and the nozzle stop lifting and are filled with cement slurry, and after the slurry returns to be normal, the drill rod and the nozzle start lifting again; when serious slurry leakage occurs in the hole in the spraying process, stopping spraying, pulling out the spraying pipe and taking a leakage stopping measure.
Optionally, in a sixth implementation manner of the first aspect of the present invention, the observing the slurry bleeding during the rotary spraying process, ensuring that the slurry bleeding amount is less than 20% of the grouting amount, and when the slurry bleeding amount is greater than 20% of the grouting amount or no slurry bleeding is performed, finding out the cause and taking corresponding measures include: when the flow is unchanged and the pressure is suddenly reduced, checking the leakage condition, and if necessary, pulling out the grouting pipe to check the sealing performance; when no bleeding or intermittent bleeding occurs, if the soil is soft, the soil is considered as a normal phenomenon, re-spraying is properly carried out, if a hole or a blind passage exists nearby, grouting is continued until bleeding, or a grouting pipe is pulled out, grouting is carried out again after the grout is solidified until bleeding, and quick-setting grout is used if necessary; and when the slurry outflow amount is more than 20% of the grouting amount, improving the rotary spraying pressure, reducing the diameter of the nozzle, or accelerating the lifting and rotating speed.
Optionally, in a seventh implementation manner of the first aspect of the present invention, before the double-grouting pipe reaches a preset depth, the cement slurry and compressed air are delivered to a nozzle of the double-grouting pipe, the drill rod and the nozzle rotate and perform a spraying operation from bottom to top, the cement slurry is sprayed from an inner nozzle at a pressure greater than 20MPa, and the compressed air is sprayed from an outer nozzle at a pressure greater than 0.7MPa, and a slurry outflow condition during the rotary spraying process is observed, the method further includes: building a sewage discharge system, introducing waste slurry generated in the construction process of the high-pressure jet grouting pile into a sedimentation tank to obtain settled clean water and settled soil, wherein the settled clean water is subjected to pollution-free discharge according to site conditions, and the settled soil is transported away when a foundation pit is excavated.
Optionally, in an eighth implementation manner of the first aspect of the present invention, when the double-grouting pipe reaches a preset depth, the cement slurry and compressed air are delivered to a nozzle of the double-grouting pipe, the drill rod and the nozzle rotate and perform a spraying operation from bottom to top, the cement slurry is sprayed out from an inner nozzle at a pressure greater than 20MPa, and the compressed air is sprayed out from an outer nozzle at a pressure greater than 0.7MPa, after observing a slurry overflow condition during the rotary spraying process, the grouting is stopped when the first drill rod exceeds the ground, the drill rod is removed quickly after the pressure drops, and when the first drill rod rises to a preset elevation of a pile top, before performing low-pressure additional spraying on the top of the rotary spraying pile for 1 to 2m, the method further includes: and (4) filling and recharging, namely inserting the grout conveying pipe into the hole 2m below the grout surface, and filling and grouting the grout used in grouting until the grout surface of the hole does not sink any more.
Optionally, in a ninth implementation manner of the first aspect of the present invention, after the low-pressure supplementary spraying is completed, the drill rod and the nozzle are flushed, the drilling machine is moved, and the operation of the next pile position is performed until all the pile positions are completely constructed, the method further includes: and (3) quality inspection, namely excavating a pile head 7 days after the pile is formed, wherein the excavation depth exceeds 0.5m below a grout stop surface, checking the uniformity of a pile body and measuring the pile forming diameter, calling a double-pipe single-action sampler 28 days after the pile is formed, vertically drilling a hole at one fourth of the pile forming diameter to take a core, and taking 3 samples at different depths to perform an unconfined compressive strength test.
In the technical scheme provided by the invention, the construction method of the high-pressure jet grouting pile test comprises the following steps: step one, construction preparation; step two, pile position lofting; thirdly, positioning a drilling machine and preparing for drilling; drilling; step five, preparing cement paste; sixthly, performing rotary spraying operation; step seven, dismantling the drill rod; and step eight, flushing and moving the drilling machine. In the embodiment of the invention, through the construction method of the high-pressure jet grouting pile test, the relevant parameters of pile forming construction are determined according to the test pile construction result, the construction efficiency is improved, and the smooth reinforcement of the tunnel ground surface is ensured.
Drawings
FIG. 1 is a schematic view of an embodiment of a construction method of a high-pressure jet grouting test pile in an embodiment of the invention;
fig. 2 is a pile position layout diagram of a high-pressure jet grouting pile test in the embodiment of the invention.
Detailed Description
The embodiment of the invention provides a construction method of a high-pressure jet grouting pile test, which is used for determining relevant parameters of pile forming construction according to a test pile construction result, improving the construction efficiency and ensuring the smooth reinforcement of the ground surface of a tunnel.
The terms "first," "second," "third," "fourth," and the like in the description and in the claims, as well as in the drawings, if any, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It will be appreciated that the data so used may be interchanged under appropriate circumstances such that the embodiments described herein may be practiced otherwise than as specifically illustrated or described herein. Furthermore, the terms "comprises," "comprising," or "having," and any variations thereof, are intended to cover non-exclusive inclusions, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
For convenience of understanding, a specific flow of an embodiment of the present invention is described below, and referring to fig. 1, an embodiment of a method for constructing a high-pressure jet grouting pile test according to an embodiment of the present invention includes:
101. construction preparation;
and carrying out geological exploration, knowing the structural conditions of pipelines, buildings, structures and other public facilities nearby the engineering, carrying out relocation and reconstruction on the pipelines needing relocation and reconstruction, and completing electrification, access, water communication and land leveling of a construction site.
Engineering geological prospecting is a geological research work carried out to find out geological factors affecting the engineering buildings, and the geological factors to be surveyed include: the construction project is characterized by comprising the following steps of topographic and geomorphic, stratigraphic lithology, engineering geological characteristics, hydrogeological conditions, earthquake motion parameters and the like, wherein before formal construction, the construction site is required to achieve the conditions of water supply, power supply, road communication, site leveling and the like, namely, construction water, power consumption and roads for entering and exiting the site are provided, and the land leveling is ensured.
102. Pile position lofting;
and measuring the construction axis of the high-pressure jet grouting pile by using a total station, testing repeatedly, confirming that the construction axis is qualified, laying pile positions by using a steel ruler and a measuring line, nailing tightly by using bamboo sticks, wherein each pile position corresponds to one bamboo stick, and the center displacement deviation of a pile hole is smaller than 20 mm.
The total station, namely the total station type electronic distance measuring instrument, is a surveying instrument system integrating the measuring functions of horizontal angle, vertical angle, distance and the like, is widely used in the field of precision engineering measurement or deformation monitoring such as construction of overground large buildings and underground tunnels, and the like, measures a released construction axis according to a construction drawing, and reports the construction axis to a supervision engineer for use after the construction axis is qualified.
103. The drilling machine is in place and drilling is ready;
the method comprises the steps of placing a drilling machine in place, leveling and centering a pile machine to enable deviation between a drill rod and a pile position to be not more than 5cm, debugging an air compressor and a slurry pump, confirming that the air compressor and the slurry pump operate normally, checking the length of the drill rod, marking a depth line beside a drilling tower to enable elevation of the bottom of a hole to meet a preset depth, conducting a low-pressure water jetting experiment, and checking whether a nozzle and pressure are normal or not.
The perpendicularity of the pile machine is adjusted, so that a drill rod is consistent with a pile position, the deviation is not more than 5cm, the perpendicularity error of a drill hole is less than 1%, common mechanical equipment accessories are required to be equipped on a construction site, and the pile machine can be timely rush-repaired when mechanical equipment breaks down.
104. Drilling;
and starting a drilling machine to drill, drilling according to the preset opening diameter, the final hole diameter and the drilling depth, and measuring the slope of the hole, wherein the opening diameter is not more than 10cm of the outer diameter of the injection pipe, the final hole diameter is more than 2cm of the outer diameter of the injection pipe, the final hole depth is more than 0.5-1.0m of the preset opening depth, and the slope of the hole is not more than 0.5%.
When the final hole is drilled, the length of a drill rod and a drilling tool needs to be measured, the allowable deviation does not exceed 5cm, the stratum condition needs to be recorded during the drilling construction of the jet grouting pile, and once the stratum does not accord with the design, the participating parties need to be informed immediately and the design parameters of the jet grouting pile are adjusted.
105. Preparing cement paste;
mixing water and cement according to a preset water-cement ratio, uniformly stirring by using a stirrer to obtain a mixture, performing primary filtration treatment and secondary filtration treatment on the mixture to obtain target filtered slurry, measuring the water-cement ratio of the target filtered slurry, and performing high-pressure pump pressurization treatment to generate cement slurry.
P.O42.5 ordinary portland cement is used as reinforcing material, and the cement must be qualified when entering the field, sampled and inspected on site, and then put into use after being qualified. All the measuring tools are required to be identified in construction, and after the cement enters a field, a cement platform is required to be raised, and rain-proof colored cloth is covered to prevent the cement from being damped and agglomerated. The cement paste is strictly prepared according to a preset proportion, caking in the cement is screened in advance, the cement paste can be continuously stirred in a mixer for preventing the cement paste from being segregated, and the cement paste is slowly poured into a hopper before grouting.
106. Performing rotary spraying operation;
when the double-grouting pipe reaches the preset depth, cement paste and compressed air are conveyed to a nozzle of the double-grouting pipe, a drill rod and the nozzle rotate and perform spraying operation from bottom to top, the cement paste is sprayed out from an inner nozzle at the pressure of more than 20MPa, the compressed air is sprayed out from an outer nozzle at the pressure of more than 0.7MPa, and the slurry outflow condition in the rotary spraying process is observed.
The rotary spraying process is continuous and uniform, if the pressure suddenly rises or drops in the rotary spraying process, and abnormal conditions such as a large amount of slurry leakage and slurry mixing occur, faults should be timely eliminated, and the repeated spraying pile connection should be deepened by 0.5m when the pile connection is repeated, so that the pile breakage is prevented. The slurry breaking phenomenon can not occur in the slurry pressing stage, the slurry conveying pipeline can not be blocked, if the pile forming process is stopped due to reasons, the slurry is repeatedly lapped up and down on the slurry breaking surface by not less than 0.5m when slurry supply is resumed.
107. Removing the drill rod;
and when the first drill rod exceeds the ground, stopping grouting, quickly removing the drill rod after the pressure is reduced, and when the first drill rod rises to a preset elevation of the pile top, performing low-pressure supplementary spraying on the top of the rotary spraying pile for 1-2 m.
When the drill rod is lifted to the designed elevation of the pile top, in order to avoid shrinkage of slurry after mixing of a mixer, and to cause the cavity at the top of the jet grouting pile, low-pressure supplementary grouting of 1-2m is needed.
108. Flushing and moving the drilling machine;
and after the low-pressure supplementary spraying is finished, washing the drill rod and the nozzle, moving the drilling machine, and performing operation of the next pile position until all the pile positions are constructed.
After the low-pressure supplementary spraying is carried out on the pile top, the grouting pipe is quickly pulled out, and the pipe section is washed by clear water so as to prevent the grouting pipe from being coagulated and blocked.
In the embodiment of the invention, the construction method of the high-pressure jet grouting pile test is adopted, and the relevant parameters of pile forming construction are determined according to the test pile construction result, so that the construction efficiency is improved, and the smooth reinforcement of the tunnel ground surface is ensured.
Another embodiment of the construction method of the high-pressure jet grouting pile test in the embodiment of the invention comprises the following steps:
step one, construction preparation: and carrying out geological exploration, knowing the structural conditions of pipelines, buildings, structures and other public facilities nearby the engineering, carrying out relocation and reconstruction on the pipelines needing relocation and reconstruction, and completing electrification, access, water communication and land leveling of a construction site.
Engineering geological prospecting is a geological research work carried out to find out geological factors affecting the engineering buildings, and the geological factors to be surveyed include: the construction project is characterized by comprising the following steps of topographic and geomorphic, stratigraphic lithology, engineering geological characteristics, hydrogeological conditions, earthquake motion parameters and the like, wherein before formal construction, the construction site is required to achieve the conditions of water supply, power supply, road communication, site leveling and the like, namely, construction water, power consumption and roads for entering and exiting the site are provided, and the land leveling is ensured.
Step two, pile position lofting: and measuring the construction axis of the high-pressure jet grouting pile by using a total station, testing repeatedly, confirming that the construction axis is qualified, laying pile positions by using a steel ruler and a measuring line, nailing tightly by using bamboo sticks, wherein each pile position corresponds to one bamboo stick, and the center displacement deviation of a pile hole is smaller than 20 mm.
The total station, namely the total station type electronic distance measuring instrument, is a surveying instrument system integrating the measuring functions of horizontal angle, vertical angle, distance and the like, is widely used in the field of precision engineering measurement or deformation monitoring such as construction of overground large buildings and underground tunnels, and the like, measures a released construction axis according to a construction drawing, and reports the construction axis to a supervision engineer for use after the construction axis is qualified.
Step three, positioning and drilling preparation of a drilling machine: the method comprises the steps of placing a drilling machine in place, leveling and centering a pile machine to enable deviation between a drill rod and a pile position to be not more than 5cm, debugging an air compressor and a slurry pump, confirming that the air compressor and the slurry pump operate normally, checking the length of the drill rod, marking a depth line beside a drilling tower to enable elevation of the bottom of a hole to meet a preset depth, conducting a low-pressure water jetting experiment, and checking whether a nozzle and pressure are normal or not.
The perpendicularity of the pile machine is adjusted, so that a drill rod is consistent with a pile position, the deviation is not more than 5cm, the perpendicularity error of a drill hole is less than 1%, common mechanical equipment accessories are required to be equipped on a construction site, and the pile machine can be timely rush-repaired when mechanical equipment breaks down.
Step four, drilling: and starting a drilling machine to drill, drilling according to the preset opening diameter, the final hole diameter and the drilling depth, and measuring the slope of the hole, wherein the opening diameter is not more than 10cm of the outer diameter of the injection pipe, the final hole diameter is more than 2cm of the outer diameter of the injection pipe, the final hole depth is more than 0.5-1.0m of the preset opening depth, and the slope of the hole is not more than 0.5%.
When the final hole is drilled, the length of a drill rod and a drilling tool needs to be measured, the allowable deviation does not exceed 5cm, the stratum condition needs to be recorded during the drilling construction of the jet grouting pile, and once the stratum does not accord with the design, the participating parties need to be informed immediately and the design parameters of the jet grouting pile are adjusted.
And step five, adding water into the barrel, adding qualified P.O42.5 cement, and uniformly mixing in a stirrer according to a preset water cement ratio to obtain a mixture, wherein the P.O42.5 cement is ordinary cement with the cement strength of 42.5, and the water cement ratio is 1-1.5.
Before the water and the cement are mixed, the method further comprises the following steps: calculating the unit pulp amount, wherein the unit pulp amount is the pulp amount sprayed in unit time, and the calculation formula is as follows: q ═ Q · (1+ β) (H/v) ·; wherein Q is the pulp amount and the unit is m3H is the rotary spraying length in m, q is the spraying amount in m3And/min, beta is loss coefficient and ranges from 0.1 to 0.2, v is lifting speed and has the unit of m/min, and the total slurry amount is calculated according to the unit slurry amount and the jet duration to determine the cement amount.
And step six, performing primary filtration treatment on the mixture to obtain intermediate filtered slurry and flowing the intermediate filtered slurry into a slurry pool, wherein the primary filtration treatment comprises the step of filtering the mixture through a filter screen.
The slurry is prepared within one hour before rotary spraying, hard gravels are filtered through primary filtration treatment, pipelines and nozzles are prevented from being blocked, and a proper amount of additives and blends can be added according to requirements in order to prevent cement paste from being segregated.
And seventhly, performing secondary filtration treatment on the intermediate filtered slurry to obtain target filtered slurry, wherein the secondary filtration treatment comprises pumping the intermediate filtered slurry into a filter sieve through a slurry pump, and performing secondary filtration.
The mud filter sieve is designed for screening special materials by enlarging a feed inlet on the basis of a common filter sieve, and is a machine type with large feeding amount, capability of preventing materials from splashing and easiness in observing a screen mesh. And (5) further screening sand and stone through secondary filtration treatment to obtain target filtration slurry.
And step eight, measuring the water-cement ratio of the target filtering slurry, pressurizing by a high-pressure pump to generate cement slurry, and conveying the cement slurry to a drilling machine for rotary spraying through a high-pressure pipe.
The high-pressure pump is a device for providing high-pressure power for high-pressure rotary spraying cement paste, is used for strengthening and reinforcing foundations of buildings, roads and the like, and can also be used for breaking rock and breaking coal by using high-pressure water jet.
Ninth, rotary spraying operation: when the double-grouting pipe reaches the preset depth, cement paste and compressed air are conveyed to a nozzle of the double-grouting pipe, a drill rod and the nozzle rotate and perform spraying operation from bottom to top, the cement paste is sprayed out from an inner nozzle at the pressure of more than 20MPa, the compressed air is sprayed out from an outer nozzle at the pressure of more than 0.7MPa, and the slurry outflow condition in the rotary spraying process is observed.
The rotary spraying process is continuous and uniform, if the pressure suddenly rises or drops in the rotary spraying process, and abnormal conditions such as a large amount of slurry leakage and slurry mixing occur, faults should be timely eliminated, and the repeated spraying pile connection should be deepened by 0.5m when the pile connection is repeated, so that the pile breakage is prevented. The slurry breaking phenomenon can not occur in the slurry pressing stage, the slurry conveying pipeline can not be blocked, if the pile forming process is stopped due to reasons, the slurry is repeatedly lapped up and down on the slurry breaking surface by not less than 0.5m when slurry supply is resumed.
Step ten, dismantling a drill rod: and when the first drill rod exceeds the ground, stopping grouting, quickly removing the drill rod after the pressure is reduced, and when the first drill rod rises to a preset elevation of the pile top, performing low-pressure supplementary spraying on the top of the rotary spraying pile for 1-2 m.
When the drill rod is lifted to the designed elevation of the pile top, in order to avoid shrinkage of slurry after mixing of a mixer, and to cause the cavity at the top of the jet grouting pile, low-pressure supplementary grouting of 1-2m is needed.
Step eleven, washing and moving the drilling machine: and after the low-pressure supplementary spraying is finished, washing the drill rod and the nozzle, moving the drilling machine, and performing operation of the next pile position until all the pile positions are constructed.
After the low-pressure supplementary spraying is carried out on the pile top, the grouting pipe is quickly pulled out, and the pipe section is washed by clear water so as to prevent the grouting pipe from being coagulated and blocked.
In the embodiment of the invention, the construction method of the high-pressure jet grouting pile test is adopted, and the relevant parameters of pile forming construction are determined according to the test pile construction result, so that the construction efficiency is improved, and the smooth reinforcement of the tunnel ground surface is ensured.
Another embodiment of the construction method of the high-pressure jet grouting pile test in the embodiment of the invention comprises the following steps:
step one, construction preparation: and carrying out geological exploration, knowing the structural conditions of pipelines, buildings, structures and other public facilities nearby the engineering, carrying out relocation and reconstruction on the pipelines needing relocation and reconstruction, and completing electrification, access, water communication and land leveling of a construction site.
Engineering geological prospecting is a geological research work carried out to find out geological factors affecting the engineering buildings, and the geological factors to be surveyed include: the construction project is characterized by comprising the following steps of topographic and geomorphic, stratigraphic lithology, engineering geological characteristics, hydrogeological conditions, earthquake motion parameters and the like, wherein before formal construction, the construction site is required to achieve the conditions of water supply, power supply, road communication, site leveling and the like, namely, construction water, power consumption and roads for entering and exiting the site are provided, and the land leveling is ensured.
Step two, pile position lofting: and measuring the construction axis of the high-pressure jet grouting pile by using a total station, testing repeatedly, confirming that the construction axis is qualified, laying pile positions by using a steel ruler and a measuring line, nailing tightly by using bamboo sticks, wherein each pile position corresponds to one bamboo stick, and the center displacement deviation of a pile hole is smaller than 20 mm.
The total station, namely the total station type electronic distance measuring instrument, is a surveying instrument system integrating the measuring functions of horizontal angle, vertical angle, distance and the like, is widely used in the field of precision engineering measurement or deformation monitoring such as construction of overground large buildings and underground tunnels, and the like, measures a released construction axis according to a construction drawing, and reports the construction axis to a supervision engineer for use after the construction axis is qualified.
Step three, positioning and drilling preparation of a drilling machine: the method comprises the steps of placing a drilling machine in place, leveling and centering a pile machine to enable deviation between a drill rod and a pile position to be not more than 5cm, debugging an air compressor and a slurry pump, confirming that the air compressor and the slurry pump operate normally, checking the length of the drill rod, marking a depth line beside a drilling tower to enable elevation of the bottom of a hole to meet a preset depth, conducting a low-pressure water jetting experiment, and checking whether a nozzle and pressure are normal or not.
The perpendicularity of the pile machine is adjusted, so that a drill rod is consistent with a pile position, the deviation is not more than 5cm, the perpendicularity error of a drill hole is less than 1%, common mechanical equipment accessories are required to be equipped on a construction site, and the pile machine can be timely rush-repaired when mechanical equipment breaks down.
Step four, drilling: and starting a drilling machine to drill, drilling according to the preset opening diameter, the final hole diameter and the drilling depth, and measuring the slope of the hole, wherein the opening diameter is not more than 10cm of the outer diameter of the injection pipe, the final hole diameter is more than 2cm of the outer diameter of the injection pipe, the final hole depth is more than 0.5-1.0m of the preset opening depth, and the slope of the hole is not more than 0.5%.
When the final hole is drilled, the length of a drill rod and a drilling tool needs to be measured, the allowable deviation does not exceed 5cm, the stratum condition needs to be recorded during the drilling construction of the jet grouting pile, and once the stratum does not accord with the design, the participating parties need to be informed immediately and the design parameters of the jet grouting pile are adjusted.
And step five, adding water into the barrel, adding qualified P.O42.5 cement, and uniformly mixing in a stirrer according to a preset water cement ratio to obtain a mixture, wherein the P.O42.5 cement is ordinary cement with the cement strength of 42.5, and the water cement ratio is 1-1.5.
Before the water and the cement are mixed, the method further comprises the following steps: calculating the unit pulp amount, wherein the unit pulp amount is the pulp amount sprayed in unit time, and the calculation formula is as follows: q ═ Q · (1+ β) (H/v) ·; wherein Q is the pulp amount and the unit is m3H is the rotary spraying length in m, q is the spraying amount in m3And/min, beta is loss coefficient and ranges from 0.1 to 0.2, v is lifting speed and has the unit of m/min, and the total slurry amount is calculated according to the unit slurry amount and the jet duration to determine the cement amount.
And step six, performing primary filtration treatment on the mixture to obtain intermediate filtered slurry and flowing the intermediate filtered slurry into a slurry pool, wherein the primary filtration treatment comprises the step of filtering the mixture through a filter screen.
The slurry is prepared within one hour before rotary spraying, hard gravels are filtered through primary filtration treatment, pipelines and nozzles are prevented from being blocked, and a proper amount of additives and blends can be added according to requirements in order to prevent cement paste from being segregated.
And seventhly, performing secondary filtration treatment on the intermediate filtered slurry to obtain target filtered slurry, wherein the secondary filtration treatment comprises pumping the intermediate filtered slurry into a filter sieve through a slurry pump, and performing secondary filtration.
The mud filter sieve is designed for screening special materials by enlarging a feed inlet on the basis of a common filter sieve, and is a machine type with large feeding amount, capability of preventing materials from splashing and easiness in observing a screen mesh. And (5) further screening sand and stone through secondary filtration treatment to obtain target filtration slurry.
And step eight, measuring the water-cement ratio of the target filtering slurry, pressurizing by a high-pressure pump to generate cement slurry, and conveying the cement slurry to a drilling machine for rotary spraying through a high-pressure pipe.
The high-pressure pump is a device for providing high-pressure power for high-pressure rotary spraying cement paste, is used for strengthening and reinforcing foundations of buildings, roads and the like, and can also be used for breaking rock and breaking coal by using high-pressure water jet.
And step nine, when the double grouting pipe reaches the preset depth and the nozzle reaches the preset elevation, performing jet grouting.
The jet grouting pile adopts a double-pipe method high-pressure jet grouting process, continuously operates from bottom to top, and when the jet pipe reaches a preset depth, the nozzle can simultaneously jet high-pressure slurry and jet of air to impact and damage a soil body.
Step ten, conveying the cement paste and compressed air to a nozzle of a double-grouting pipe, wherein the flow rate of the cement paste is more than 30L/min, the nozzle rotates and is lifted from bottom to top to perform spraying operation, the rotary spraying lifting speed is 10-15cm/min, the cement paste is sprayed out from an inner nozzle under the pressure of more than 20MPa, and the compressed air is sprayed out from an outer nozzle under the pressure of more than 0.7 MPa.
The nozzles rotate and lift while spraying, the spraying operation is carried out from bottom to top, whether the initial setting time of slurry, the grouting flow, the pressure, the rotating and lifting speed and other parameters meet the design requirements or not is checked at any time, and the recording is made at any time to draw an operation process curve.
And step eleven, when the spraying is interrupted in the spraying process, carrying out repeated spraying overlapping according to the interruption condition.
When the injection pipe is disassembled in the injection process, the repeated injection is carried out after the injection is recovered, and the lap joint length is not less than 0.1 m; when the spraying process is interrupted due to reasons, the repeated spraying is carried out after the spraying is resumed, and the lap joint length is not less than 0.5 m; when the jet interruption exceeds the initial setting time of the slurry, hole sweeping is carried out, after jet is resumed, re-jet is carried out, and the lap joint length is not less than 1 m.
And step twelve, when slurry leaks in the holes in the spraying process, taking measures according to the slurry leakage degree.
When slurry leaks from the hole in the jetting process, the drill rod and the nozzle stop lifting and are filled with cement slurry, and after the slurry returns to be normal, the drill rod and the nozzle start lifting again; when serious slurry leakage occurs in the hole in the spraying process, stopping spraying, pulling out the spraying pipe and taking a leakage stopping measure.
Step thirteen, observing the slurry bleeding situation in the rotary spraying process, ensuring that the slurry bleeding amount is less than 20% of the grouting amount, and finding out the reason and taking corresponding measures when the slurry bleeding amount is more than 20% of the grouting amount or the slurry does not bleed.
When the flow is unchanged and the pressure is suddenly reduced, checking the leakage condition, and if necessary, pulling out the grouting pipe to check the sealing performance; when no bleeding or intermittent bleeding occurs, if the soil is soft, the soil is considered as a normal phenomenon, re-spraying is properly carried out, if a hole or a blind passage exists nearby, grouting is continued until bleeding, or a grouting pipe is pulled out, grouting is carried out again after the grout is solidified until bleeding, and quick-setting grout is used if necessary; when the slurry outflow is more than 20% of the slurry injection amount, the rotary spraying pressure is increased, the diameter of the nozzle is reduced, or the lifting speed and the rotating speed are increased.
Fourteen steps of dismantling the drill rod: and when the first drill rod exceeds the ground, stopping grouting, quickly removing the drill rod after the pressure is reduced, and when the first drill rod rises to a preset elevation of the pile top, performing low-pressure supplementary spraying on the top of the rotary spraying pile for 1-2 m.
When the drill rod is lifted to the designed elevation of the pile top, in order to avoid shrinkage of slurry after mixing of a mixer, and to cause the cavity at the top of the jet grouting pile, low-pressure supplementary grouting of 1-2m is needed.
Step fifteen, washing and moving the drilling machine: and after the low-pressure supplementary spraying is finished, washing the drill rod and the nozzle, moving the drilling machine, and performing operation of the next pile position until all the pile positions are constructed.
After the low-pressure supplementary spraying is carried out on the pile top, the grouting pipe is quickly pulled out, and the pipe section is washed by clear water so as to prevent the grouting pipe from being coagulated and blocked.
In the embodiment of the invention, the construction method of the high-pressure jet grouting pile test is adopted, and the relevant parameters of pile forming construction are determined according to the test pile construction result, so that the construction efficiency is improved, and the smooth reinforcement of the tunnel ground surface is ensured.
Referring to fig. 2, fig. 2 is a diagram of pile position arrangement of a high-pressure jet grouting pile test according to an embodiment of the present invention, including:
and (3) 12 groups of test piles, each group comprises 2, the total number of the test piles is 24, the pile length is 16.5m, the pile diameter is 0.6m, the longitudinal and transverse spacing is 1.2m, and the test piles are arranged according to the positions shown in the figure 2.
Referring to table 1, table 1 is a table of process laboratory ratios in the examples of the present invention, including:
TABLE 1
And water cement ratios and cement mixing amounts corresponding to 12 groups of rotary jet piles, wherein the water cement ratios of the first group to the fourth group are all 1:1, the water cement ratios of the fifth group to the eighth group are all 1.25:1, the water cement ratios of the ninth group to the tenth group are all 1.5:1, the cement mixing amounts of the first group, the fifth group and the ninth group are all 140kg/m, the cement mixing amounts of the second group, the sixth group and the tenth group are all 160kg/m, the cement mixing amounts of the third group, the seventh group and the tenth group are all 180kg/m, and the cement mixing amounts of the fourth group, the eighth group and the tenth group are all 200 kg/m.
Referring to table 2, table 2 is a reference table of main technical parameters for construction of a jet grouting pile in the embodiment of the present invention, and includes:
TABLE 2
The pressure of the cement paste is 20-40MPa, the flow rate of the cement paste is 80-120L/min, the air pressure is 0.7-0.8MPa, the water-cement ratio is 1-1.5, the lifting speed of a drill rod is 10-15cm/min, the rotating speed of the drill rod is 10-15r/min, the diameter of a nozzle is 2.4mm, and the length of a high-pressure pipe is less than 50 m.
The above-mentioned embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (10)
1. A construction method for testing a high-pressure jet grouting pile is characterized by comprising the following steps:
step one, construction preparation: carrying out geological exploration, knowing the structural conditions of pipelines, buildings, structures and other public facilities near the engineering, carrying out relocation and reconstruction on the pipelines needing relocation and reconstruction, and completing electrification, access, water communication and land leveling of a construction site;
step two, pile position lofting: measuring the construction axis of the high-pressure jet grouting pile by using a total station, performing repeated test, confirming that the construction axis is qualified, laying pile positions by using a steel ruler and a measuring line, and nailing the pile positions tightly by using bamboo sticks, wherein each pile position corresponds to one bamboo stick, so that the center displacement deviation of a pile hole is smaller than 20 mm;
step three, positioning and drilling preparation of a drilling machine: the method comprises the steps that a drilling machine is in place, leveling and centering treatment are carried out on a pile machine, so that the deviation between a drill rod and a pile position is not more than 5cm, an air compressor and a slurry pump are debugged, the air compressor and the slurry pump are confirmed to be normally operated, the length of the drill rod is checked, a depth line is marked beside a drilling tower, the elevation of the bottom of a hole meets the preset depth, a low-pressure water jetting experiment is carried out, and whether a nozzle and pressure are;
step four, drilling: starting a drilling machine to drill, drilling according to a preset opening caliber, a final hole caliber and a drilling depth, and measuring the hole slope, wherein the opening caliber is not more than 10cm of the outer diameter of the injection pipe, the final hole caliber is more than 2cm of the outer diameter of the injection pipe, the final hole depth is more than 0.5-1.0m of the preset opening depth, and the hole slope is not more than 0.5%;
step five, preparing cement paste: mixing water and cement according to a preset water-cement ratio, uniformly stirring by using a stirrer to obtain a mixture, performing primary filtration treatment and secondary filtration treatment on the mixture to obtain target filtered slurry, measuring the water-cement ratio of the target filtered slurry, and performing pressurization treatment by using a high-pressure pump to generate cement slurry;
step six, jet grouting operation: when the double-grouting pipe reaches a preset depth, conveying the cement paste and compressed air to a nozzle of the double-grouting pipe, rotating the drill rod and the nozzle, performing spraying operation from bottom to top, spraying the cement paste from an inner nozzle at a pressure of more than 20MPa, spraying the compressed air from an outer nozzle at a pressure of more than 0.7MPa, and observing the slurry outflow condition in the rotary spraying process;
step seven, dismantling the drill rod: stopping grouting when the first drill rod exceeds the ground, quickly removing the drill rod after the pressure is reduced, and performing low-pressure supplementary spraying on the top of the rotary spraying pile for 1-2m when the first drill rod rises to a preset elevation of the pile top;
step eight, washing and moving the drilling machine: and after the low-pressure supplementary spraying is finished, washing the drill rod and the nozzle, moving the drilling machine, and performing operation of the next pile position until all the pile positions are constructed.
2. The construction method of the high-pressure jet grouting pile test according to claim 1, wherein the step of mixing water and cement according to a preset water-cement ratio, uniformly stirring the mixture by using a stirrer to obtain a mixture, performing primary filtration treatment and secondary filtration treatment on the mixture to obtain target filtration slurry, measuring the water-cement ratio of the target filtration slurry, and performing high-pressure pump pressurization treatment to generate cement slurry comprises the steps of:
adding water into a barrel, adding qualified P.O42.5 cement, and uniformly mixing in a stirrer according to a preset water cement ratio to obtain a mixture, wherein the P.O42.5 cement is ordinary cement with the cement strength of 42.5, and the water cement ratio is 1-1.5;
performing primary filtration treatment on the mixture to obtain intermediate filtered slurry and flowing the intermediate filtered slurry into a slurry pool, wherein the primary filtration treatment comprises the step of filtering the mixture through a filter screen;
performing secondary filtration treatment on the intermediate filtered slurry to obtain target filtered slurry, wherein the secondary filtration treatment comprises pumping the intermediate filtered slurry into a filter sieve through a slurry pump for secondary filtration;
and measuring the water-cement ratio of the target filtering slurry, pressurizing the target filtering slurry by a high-pressure pump to generate cement slurry, and conveying the cement slurry to a drilling machine for rotary spraying through a high-pressure pipe.
3. The method for constructing a high-pressure jet grouting pile test according to claim 2, wherein before the mixing of water and cement according to the preset water cement ratio, the method further comprises:
calculating unit pulp amount, wherein the unit pulp amount is the pulp amount sprayed in unit time, and the calculation formula is as follows:
Q＝(H/v)·q·(1+β)；
wherein Q is the pulp amount and the unit is m3H is the rotary spraying length in m, q is the spraying amount in m3B is loss coefficient, the range is 0.1-0.2, v is lifting speed, and the unit is m/min;
and calculating the total slurry amount according to the unit slurry amount and the jet duration time, and determining the cement amount.
4. The method for constructing a high-pressure jet grouting pile test according to claim 1, wherein when the double grouting pipe reaches a preset depth, the cement paste and compressed air are delivered to the nozzle of the double grouting pipe, the drill rod and the nozzle rotate and lift from bottom to top to perform a spraying operation, the cement paste is sprayed out from the inner nozzle at a pressure greater than 20MPa, and the compressed air is sprayed out from the outer nozzle at a pressure greater than 0.7MPa, and observing the slurry outflow during the jet grouting process comprises:
when the double grouting pipe reaches the preset depth and the nozzle reaches the preset elevation, performing jet grouting;
conveying the cement paste and compressed air to a nozzle of the double-grouting pipe, wherein the flow rate of the cement paste is more than 30L/min, the nozzle rotates and is lifted from bottom to top to perform spraying operation, the rotary spraying lifting speed is 10-15cm/min, the cement paste is sprayed out from an inner nozzle at the pressure of more than 20MPa, and the compressed air is sprayed out from an outer nozzle at the pressure of more than 0.7 MPa;
when the spraying is interrupted in the spraying process, carrying out repeated spraying and lapping according to the interruption condition;
when slurry leakage occurs in the holes in the spraying process, measures are taken according to the slurry leakage degree;
observing the slurry bleeding condition in the rotary spraying process, ensuring that the slurry bleeding amount is less than 20% of the grouting amount, and finding out the reason and taking corresponding measures when the slurry bleeding amount is more than 20% of the grouting amount or the slurry is not bled.
5. The construction method of the high-pressure jet grouting pile test according to claim 4, wherein if the jet is interrupted in the jet process, the repeated jet lapping according to the interruption condition comprises the following steps:
when the injection pipe is disassembled in the injection process, the repeated injection is carried out after the injection is recovered, and the lap joint length is not less than 0.1 m;
when the spraying process is interrupted due to reasons, the repeated spraying is carried out after the spraying is resumed, and the lap joint length is not less than 0.5 m;
when the jet interruption exceeds the initial setting time of the slurry, hole sweeping is carried out, after jet is resumed, re-jet is carried out, and the lap joint length is not less than 1 m.
6. The construction method of the high-pressure jet grouting pile test according to claim 4, wherein if slurry leakage occurs in the hole during the jetting process, taking measures according to the slurry leakage degree comprises:
when slurry leaks from the hole in the jetting process, the drill rod and the nozzle stop lifting and are filled with cement slurry, and after the slurry returns to be normal, the drill rod and the nozzle start lifting again;
when serious slurry leakage occurs in the hole in the spraying process, stopping spraying, pulling out the spraying pipe and taking a leakage stopping measure.
7. The construction method of the high-pressure jet grouting pile test according to claim 4, wherein the observing the slurry bleeding during the jet grouting process ensures that the slurry bleeding amount is less than 20% of the grouting amount, and when the slurry bleeding amount is more than 20% of the grouting amount or no slurry bleeding is performed, finding out the cause and taking corresponding measures comprises:
when the flow is unchanged and the pressure is suddenly reduced, checking the leakage condition, and if necessary, pulling out the grouting pipe to check the sealing performance;
when no bleeding or intermittent bleeding occurs, if the soil is soft, the soil is considered as a normal phenomenon, re-spraying is properly carried out, if a hole or a blind passage exists nearby, grouting is continued until bleeding, or a grouting pipe is pulled out, grouting is carried out again after the grout is solidified until bleeding, and quick-setting grout is used if necessary;
and when the slurry outflow amount is more than 20% of the grouting amount, improving the rotary spraying pressure, reducing the diameter of the nozzle, or accelerating the lifting and rotating speed.
8. The method for constructing a high-pressure jet grouting pile test according to claim 1, wherein when the double-grouting pipe reaches a predetermined depth, the grout and compressed air are delivered to the nozzle of the double-grouting pipe, the drill rod and the nozzle rotate and perform jet operation from bottom to top, the grout is ejected from the inner nozzle at a pressure of more than 20MPa, the compressed air is ejected from the outer nozzle at a pressure of more than 0.7MPa, and before observing grout outflow during the jet grouting, the method further comprises:
building a sewage discharge system, introducing waste slurry generated in the construction process of the high-pressure jet grouting pile into a sedimentation tank to obtain settled clean water and settled soil, wherein the settled clean water is subjected to pollution-free discharge according to site conditions, and the settled soil is transported away when a foundation pit is excavated.
9. The method of claim 1, wherein the cement slurry and compressed air are delivered to the nozzle of the double-grouting pipe when the double-grouting pipe reaches a predetermined depth, the drill rod and the nozzle rotate and perform a spraying operation from bottom to top, the cement slurry is sprayed from the inner nozzle at a pressure greater than 20MPa and the compressed air is sprayed from the outer nozzle at a pressure greater than 0.7MPa, after observing a slurry overflow condition during the rotary spraying process, the grouting is stopped when the first drill rod exceeds the ground, the drill rod is rapidly removed after the pressure drops, and when the first drill rod rises to a predetermined elevation of the pile top, the method further comprises the following steps before performing a low-pressure supplementary spraying of 1-2m on the top of the rotary sprayed pile:
and (4) filling and recharging, namely inserting the grout conveying pipe into the hole 2m below the grout surface, and filling and grouting the grout used in grouting until the grout surface of the hole does not sink any more.
10. The method for constructing the high-pressure jet grouting pile test according to any one of claims 1 to 9, wherein after the low-pressure jet grouting is completed, the drill rod and the nozzle are flushed and the drilling machine is moved to perform the operation of the next pile position until all the pile positions are constructed, and the method further comprises the following steps:
and (3) quality inspection, namely excavating a pile head 7 days after the pile is formed, wherein the excavation depth exceeds 0.5m below a grout stop surface, checking the uniformity of a pile body and measuring the pile forming diameter, calling a double-pipe single-action sampler 28 days after the pile is formed, vertically drilling a hole at one fourth of the pile forming diameter to take a core, and taking 3 samples at different depths to perform an unconfined compressive strength test.
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| CN113916522A (en) * | 2021-10-11 | 2022-01-11 | 中铁西北科学研究院有限公司 | Test method for obtaining jet grouting parameters suitable for jet grouting pile construction environment in laboratory |
| CN113916522B (en) * | 2021-10-11 | 2022-06-24 | 中铁西北科学研究院有限公司 | Test method for obtaining jet grouting parameters suitable for jet grouting pile construction environment in laboratory |
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