CN110485413B - Combined type protection rapid hole forming method for pile foundation of viaduct adjacent to subway - Google Patents
Combined type protection rapid hole forming method for pile foundation of viaduct adjacent to subway Download PDFInfo
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- 238000005553 drilling Methods 0.000 claims abstract description 49
- 239000004568 cement Substances 0.000 claims abstract description 46
- 238000003756 stirring Methods 0.000 claims abstract description 36
- 230000002787 reinforcement Effects 0.000 claims abstract description 21
- 238000004140 cleaning Methods 0.000 claims abstract description 20
- 238000012545 processing Methods 0.000 claims abstract description 6
- 239000002689 soil Substances 0.000 claims description 19
- 238000005507 spraying Methods 0.000 claims description 17
- 230000001681 protective effect Effects 0.000 claims description 14
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- 230000002457 bidirectional effect Effects 0.000 claims description 2
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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
- E02D5/38—Concrete or concrete-like piles cast in position ; Apparatus for making same making by use of mould-pipes or other moulds
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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
- E21B21/00—Methods or apparatus for flushing boreholes, e.g. by use of exhaust air from motor
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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
- E21B3/00—Rotary drilling
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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
- E21B47/00—Survey of boreholes or wells
- E21B47/04—Measuring depth or liquid level
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Abstract
The invention discloses a combined type protection rapid hole forming method for a pile foundation of an adjacent subway viaduct, which comprises the steps of measuring and lofting, drilling, building a slurry processing center, stirring a cement pile, embedding a permanent steel casing, finishing and cleaning holes, processing and placing a reinforcement cage, closing underwater concrete and the like. Aiming at the problem of small clear distance of the subway tunnel, the invention adopts a combined protection method combining the cement mixing pile, the permanent steel casing and the thick slurry, ensures the stability of the construction close to the subway pile foundation, greatly reduces the disturbance to the subway structure, plays a good protection role and ensures the construction quality and safety.
Description
Technical Field
The invention relates to the field of bridge engineering, in particular to a composite protection rapid hole forming method for a pile foundation of an overhead bridge close to a subway.
Background
The pile foundation refers to a deep foundation consisting of piles and pile caps connected with the pile tops or a single pile foundation connected with the pile foundation by columns. The construction of the pile foundation of the bridge is the most important link in the construction of each bridge, and the construction comprises the procedures of measuring a lofting pile casing, embedding a drilling steel reinforcement cage, placing a cast-in-place pile and the like.
However, for some pile foundations with special positions, the pile foundations of the pile foundations are close to subways and driveways, construction is carried out along pile foundations of existing subway bridges, the pile foundations of a main line bridge are close to subway tunnels, the theoretical minimum clear distance is only 2.25m, and the pile foundations are located in special protection areas within 3.5m of outer lines of underground engineering (station tunnels and the like) structures. In the construction process, the vibration caused in the construction process is easy to disturb the existing subway tunnel structure, destroy the adjacent subway soil body, and cause the subway tunnel structure to crack or even collapse.
Disclosure of Invention
In order to solve one of the technical problems, the invention provides a composite protection rapid hole forming method for a pile foundation of an adjacent subway viaduct.
The technical scheme adopted by the invention for solving the technical problems is as follows: a composite protection rapid hole forming method for a pile foundation close to a subway viaduct comprises the following steps: a. measuring and lofting, surveying the geological structure and determining the position of a pile foundation; b. drilling holes, and forming original holes at the pile foundation position; c. establishing a slurry treatment center, and establishing a slurry protection wall on the side surface of the original hole; d. cement mixing pile, spraying cement into soil body by using mixing pile machine and fully mixing to reinforce covering layer; e. embedding a permanent steel pile casing; f. finishing and cleaning the hole; g. processing and placing a reinforcement cage; h. and (5) pouring underwater concrete.
According to the scheme, the combined protection method combining the cement mixing pile, the permanent steel casing and the thick slurry is adopted for solving the problem of small clear distance of the subway tunnel, so that the construction stability of the pile foundation close to the subway is ensured, the construction soil quality of the cement mixing pile is improved in the hole opening stage and the drilling initial stage of a drilling machine, the soil body around the pile foundation is reinforced and protected, the permanent steel casing has the reinforcing and protecting effects on the subsequent processes of hole forming and hole cleaning and filling of the pile foundation, upper structure construction and the like, the slurry treatment center is established to realize the recycling of the slurry, and the established slurry casing penetrates through the whole hole forming process, so that the material cost is saved, the environment is well protected, the stability of the soil body around the pile foundation in the drilling initial stage is ensured, the disturbance to the subway structure is greatly reduced, the good protection effect is achieved, and.
Preferably, in the step c, a slurry retaining wall with the slurry concentration of 1.1-1.3 is arranged in the slurry processing center before the permanent steel casing is installed, and a slurry retaining wall with the slurry concentration of 1.03-1.1 is arranged after the permanent steel casing is installed.
Therefore, as the protective cylinder wall is not arranged before the permanent steel protective cylinder is not installed and the drilling depth is larger, the high-concentration slurry is configured to enhance the strength of the hole wall of the original hole, the drilling process is rapidly completed and the permanent steel protective cylinder is installed in time, and after the permanent steel protective cylinder is installed, the hole wall protection is enhanced, the slurry concentration and the slurry using amount are reduced, and the material cost is saved.
Preferably, step c further comprises a mud performance parameter test.
Therefore, through the mud performance parameter test, the changes of parameters such as the mud concentration, the viscosity, the water loss amount and the like are monitored in real time, and the mud dosage is adjusted, so that the protective wall is in the optimal protective state.
Preferably, in the step d, the cement mixing pile penetrates through a mud layer and a sand layer, and the pile end of the cement mixing pile reaches strongly weathered mudstone.
Therefore, the pile end of the mixing pile penetrates through the covering layer, and the cement mixing pile is enabled to act on the covering layer.
Preferably, the cement stirring pile in the step d adopts a two-spraying four-stirring process.
From the above, two-time cement spraying refers to two-time cement spraying, four-time stirring refers to four-time stirring, wherein the stirring pile rotates downwards and is lifted to be twice-time stirring, cement is sprayed in the stirring process, and the two-time spraying and four-time stirring process enables the effect of each-time cement stirring pile to be better and the stirring to be more uniform.
Preferably, a single row of deep cement mixing piles is adopted in the step d.
Therefore, the original hole is surrounded by the single-row deep cement mixing pile, so that the soil body on the hole wall is protected more firmly and reliably.
Preferably, in the step e, after the positioning is carried out by using a bidirectional control positioning method, a permanent steel casing is buried and fixed, and the permanent steel casing is sleeved into the original hole along the mud retaining wall.
Therefore, whether the center of the permanent steel casing coincides with the center of the pile position is calibrated, the position change and the deflection of the drilling machine and the drilling tool are detected, the vacancy is guaranteed to accurately meet the design requirement, and the permanent steel casing is accurately installed.
Preferably, the permanent steel casing in the step e is embedded into the original hole by a self-advancing or static pressure type.
Therefore, due to the vibration of subway operation, the vibration of large trains on a lane or the vibration generated in the drilling process of a drilling machine, soil bodies can be loosened and collapsed, the permanent steel casing cannot vibrate strongly in the construction process, and the vibration problem of the construction of the permanent steel casing can be effectively reduced by selecting the traditional self-propelled type or static pressure type.
Preferably, in the step b, whether the center of the calibration drill bit coincides with the center of the pile foundation position before drilling is carried out.
Therefore, the deviation of the drill bit and the pile foundation position is avoided, and the drilling position is strictly controlled.
Preferably, step f further comprises detecting the depth of the hole and the thickness of the sediments.
Therefore, after the hole is formed, the drilling depth of the display interface of the rotary drilling rig is compared with the depth of the measuring rope, and the final hole acceptance is guaranteed.
Drawings
The invention is further illustrated with reference to the following figures and examples:
FIG. 1 is a schematic view of a composite protection process according to a preferred embodiment of the present invention.
Detailed Description
Reference will now be made in detail to the present preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout.
In the description of the present invention, it should be understood that the orientation or positional relationship referred to in the description of the orientation, such as the upper, lower, front, rear, left, right, etc., is based on the orientation or positional relationship shown in the drawings, and is only for convenience of description and simplification of description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention.
In the description of the present invention, the meaning of a plurality of means is one or more, the meaning of a plurality of means is two or more, and larger, smaller, larger, etc. are understood as excluding the number, and larger, smaller, inner, etc. are understood as including the number. If the first and second are described for the purpose of distinguishing technical features, they are not to be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated or implicitly indicating the precedence of the technical features indicated.
In the description of the present invention, unless otherwise explicitly limited, terms such as arrangement, installation, connection and the like should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above terms in the present invention in combination with the specific contents of the technical solutions.
Referring to fig. 1, a preferred embodiment is that a pile foundation is located between two lines of a subway, the theoretical minimum clear distance is 2.25m, a covering layer is funnel-shaped and belongs to an extremely unstable state, the covering layer comprises a sand layer, a silt layer and a clay layer, and the depth of the covering layer is 15-16 m.
A composite protection rapid hole forming method for a pile foundation close to a subway viaduct comprises the following steps:
(1) and (6) measuring and sampling. Surveying nearby the pile foundation by a measurer, drawing an outer boundary diagram, marking the coordinates close to the subway outer edge line of the pile foundation, determining the position of the pile foundation, lofting the road on the edge line, determining the plane position relation between the pile foundation and the subway outer edge line, rechecking the measurement control point, measuring and placing the pile position of each pile after the measurement control point meets the requirement, and placing the pile driver in place.
(2) And (4) drilling holes. According to the field construction requirement, in order to reduce the disturbance of the construction process to the surrounding soil body and the subway structure as much as possible, the rotary drilling rig is selected for construction, the determined pile foundation position is drilled, a primary hole is formed preliminarily, the primary hole is the pile foundation hole formed after the rotary drilling rig conducts primary hole opening and drilling, the hole opening means that the pile foundation position is perforated preliminarily, and the drilling is conducted to deepen or enlarge the hole opening diameter.
(3) And (4) establishing a slurry treatment center and establishing a slurry protecting wall. Engineering geological conditions penetrate through a sand layer and a sludge layer, the thickness of the sand layer and the thickness of the sludge layer are thick, special treatment is needed, slurry indexes are required to be adjusted at any time according to the actual address condition on site, the slurry performance is guaranteed, a slurry treatment center is established due to the thick thickness of the sand layer and the thick thickness of the sludge layer, the slurry is recycled, a high-concentration slurry retaining wall needs to be configured due to the fact that no permanent steel retaining wall 1 is arranged and the drilling depth is large during hole guiding construction, a hole guiding process is completed quickly, and a permanent steel retaining wall 1 is installed in time.
(4) And (5) stirring the piles with cement. The cement mixing pile is used for reinforcing and protecting a covering layer in a hole opening stage and a drilling machine drilling initial stage, reinforcing and protecting hole walls around an original hole, and avoiding collapse or other problems in a follow-up construction process.
(5) The permanent steel casing 1 is embedded. The permanent steel pile casing 1 is used for preventing soil from collapsing due to loosening, cement mixing piles and thick mud protection are used during initial drilling, however, after hole cleaning, concrete pouring of steel bars and pile foundations is carried out, and due to long time and subway operation vibration or road vehicle vibration, the permanent steel pile casing 1 is designed to protect the retaining wall.
(6) And finishing and cleaning the hole. The permanent steel protective cylinder 1 is installed and then formed into a hole, the hole depth and the sediment thickness of a final hole need to be measured, the drilling depth of a display interface of a rotary drilling rig is different from the actual hole depth, the hole needs to be measured again, a hole cleaning drill bit is replaced to clean the hole, the hole depth is measured again, the hole cleaning process is carried out until the measured final hole is qualified in inspection, the hole cleaning process is used for cleaning impurities such as mud inside the final hole until all indexes of the mud at the bottom of the hole and the sediment thickness meet the standard requirements, and a steel reinforcement cage is convenient to place.
(7) And (5) processing and placing the reinforcement cage. The steel reinforcement cage is used for as basic skeleton, possesses tensile and compressive capacity, plays the effect of restraint to pile body concrete, makes it bear certain horizontal force, reaches the designing requirement after the hole depth, transfers the steel reinforcement cage to the pile hole, inserts the pipe again and carries out concrete placement.
(8) And (5) pouring underwater concrete. And (5) after the steel reinforcement cage is installed, checking the thickness of sediments at the bottom of the hole after the steel reinforcement cage is qualified, pouring concrete, and finishing the final pore-forming process.
Furthermore, disturbance of the construction process to surrounding soil bodies and subway structures is reduced as much as possible according to site construction requirements, a 50t truck crane is selected for hoisting construction of the permanent steel casing 1, and a rotary drilling rig is selected for drilling construction. The rotary drilling rig is a construction machine suitable for hole forming operation in building foundation engineering, is mainly suitable for soil layer construction of sandy soil, cohesive soil, silty soil and the like, and is widely applied to foundation construction of various foundations such as cast-in-place piles, continuous walls, foundation reinforcement and the like, the rated power of the rotary drilling rig is generally 125-450 kW, the power output torque is 120-400 kN.m, the maximum hole forming diameter can reach 1.5-4 m, and the maximum hole forming depth is 60-90 m, so that the requirements of various large-scale foundation constructions can be met. The diameter of a main line bridge used in the engineering is 2.8m at the maximum, the length of the main line bridge is 40-65 m, and therefore two models of 300kw and 360kw rotary drilling rigs are selected for construction, so that the requirement of hole forming of the pile foundation is met.
Further, according to the site confirmation of the geological exploration data of the pile foundation and the display of the geological exploration data, the cement mixing pile needs to penetrate through the sand layer and enter the strongly weathered rock layer for 2m, and is temporarily set for 18 m. The deep cement mixing pile 2 with the single row diameter of 50cm is adopted, if the mixing pile acts on the stable soil body, mutual meshing can not be referred, and the meshing thickness can also be designed to be 5-10 cm. The cement mixing pile is constructed by adopting a two-spraying four-stirring process, the pile diameter is 500mm, 42.5-grade ordinary portland cement is adopted as a material, the ash content per meter is 75kg, the water-cement ratio is 0.45-055, the high-efficiency water reducing agent is 0.5%, and the spraying pressure is not less than 0.5 MPa. The cement mixing pile can be constructed after the age of the cement mixing pile is not less than 28d and the compressive strength is not less than 1 MPa. The deep cement mixing pile is suitable for reinforcing saturated soft clay with various causes, is commonly used for reinforcing geology such as silt, mucky soil, clay, sub-clay and the like, has a pile forming depth of 30m, and has a wall forming depth of 18m by adopting a multi-head diameter pile. The two-spraying four-stirring process is characterized in that two stirring processes are adopted at each stirring position, each cycle comprises a first spraying process and a second stirring process, the spraying process refers to cement spraying, the stirring process refers to a stirring operation in the process that a cement stirring pile extends into a covering layer or is pulled out of the covering layer, each stirring pile extends into the covering layer and is pulled out, the stirring pile performs two stirring operations, namely two stirring operations, the stirring pile simultaneously sprays cement and is pulled out in the process of extending into the covering layer, namely one-spraying two stirring operations are completed, and the two continuous operations are performed at the same position, namely the two-spraying four-stirring process. In this embodiment, the machine used for the cement mixing pile is a deep mixing pile machine.
Furthermore, the permanent steel casing 1 cannot vibrate strongly during construction, and the traditional self-advancing type or static pressure type is selected, wherein the self-advancing type is to place the permanent steel casing 1 into a pile foundation hole by using a crane in a hoisting mode, and the static pressure type is to use forward and reverse rotation of a power head to rub and a pressurizing oil cylinder to pressurize so that the permanent steel casing 1 is cut into the soil. In the embodiment, the self-advancing embedded permanent steel casing 1 is adopted, so that the generation of large vibration is avoided, and the collapse of an original hole is prevented.
Furthermore, after the hole is opened, the diameter of the drill bit is adjusted by the drilling machine to be 5cm larger than that of the permanent steel casing 1, the drilling machine continues to drill after the original hole position is aligned and vertically adjusted, and the drilling process requires slow drilling at a constant speed, so that the subway structure is prevented from being influenced by overlarge vibration. The method comprises the steps that a field technician masters the drilling depth in real time, when the hole depth reaches the elevation of a position 5m below a subway structure, drilling is stopped, the permanent steel protective cylinder 1 starts to be hoisted, the permanent steel protective cylinder 1 is buried by a crane, hoisting points are arranged at the symmetrical positions of the protective cylinders, the center of the permanent steel protective cylinder 1 is kept consistent with the center of a hole leading hole in the burying process, the field technician monitors the perpendicularity and plane position deviation of the permanent steel protective cylinder 1 in real time, and the deviation is corrected in time. When the diameters of pile foundations are different, the specifications of the adopted permanent steel casing 1 are also different, for example, when the diameters of the pile foundations are 180cm, 220cm, 250cm and 280cm, the diameters of the adopted permanent steel casing 1 are 200cm, 250cm, 280cm and 310cm respectively, and the thicknesses of the permanent steel casing 1 are 8mm, 10mm, 20mm and 20mm, so that the pile foundation is suitable for different pile foundation holes.
Furthermore, after the cement retaining wall is set up, parameter testing needs to be performed on the slurry performance, in this embodiment, the parameters for measuring the retaining wall slurry are volume, viscosity, water loss, mud skin thickness, colloid content, sand content and PH value, the volume is weighed by a 1006 type slurry specific gravity, the viscosity is measured by a viscometer, and the water loss is measured by a water loss meter. The mud skin rate is measured by a ruler, the colloid rate is measured by a measuring cylinder, the sand content is measured by a sand rate tester, and the pH value is measured by a pH test paper. According to geological conditions, the slurry treatment center outputs slurry, the parameters are kept within a proper range, in the embodiment, the parameters on the slurry retaining wall of the newly prepared slurry and the hole cleaning slurry are different, and the capacity, the viscosity, the water loss, the thickness of the slurry skin, the colloid rate and the pH value of the sand content are respectively 1.1-1.3 and 1.03-1.1, 16-22 and 17-20, less than 18 and less than 20, respectively less than 1.5, more than or equal to 95, more than or equal to 98, less than 4 and less than 2, respectively 6.5-10, wherein the newly prepared slurry refers to the slurry parameter on the slurry retaining wall before the permanent steel retaining tube 1 is installed, and the hole cleaning slurry refers to the slurry parameter of the slurry retaining wall after the permanent steel retaining tube 1 is installed. Therefore, during the hole leading construction, as the permanent steel casing 1 is not arranged and the drilling depth is larger, a high-concentration slurry retaining wall needs to be configured, the procedure is quickly completed, the permanent steel casing 1 is installed in time, and the slurry concentration can be properly reduced after the permanent steel casing 1 is installed.
Furthermore, in order to effectively exert the protection effect of the cement mixing pile, the cement mixing pile penetrates through a sludge layer, and the pile end of the cement mixing pile reaches a strongly weathered sludge layer.
Furthermore, before construction in the step (2), the central point of each pile position is detected according to the measurement control network, whether the center of the drill bit is overlapped with the center of the pile position is checked before drilling, and whether position deviation and deflection of the drilling machine and the drilling tool occur or not is detected in the whole construction process, so that the accuracy of the vacancy is ensured to meet the design requirement.
Further, detecting the depth of the hole and the thickness of the sediment: after the hole is formed, the drilling depth L1 of a display interface of the rotary drilling machine is compared with the hole depth L2 measured by a measuring rope, if L2 is smaller than L1, the bottom cleaning drill bit can be replaced to clean the bottom, and the hole depth is tested again. And after the inspection and acceptance are qualified, cleaning the holes immediately. In the embodiment, the hole is cleaned by adopting a reverse circulation method until all indexes of the slurry at the bottom of the hole and the thickness of the sediments meet the standard requirement. The specific gravity of the slurry within 50cm of the bottom of the hole is controlled to be 1.03-1.1, the viscosity is 17-20 s, the sand content is less than 2%, and the water level in the hole is kept during hole cleaning so as to ensure the pressure of the slurry in the hole. The hole cleaning is carried out twice, and the hole cleaning is carried out once after the drilling depth reaches the design depth and the hole inspection is qualified. And secondary hole cleaning meets the design requirement, and a reinforcement cage is arranged.
Furthermore, after the steel reinforcement cage is processed and the secondary hole cleaning is qualified, hoisting construction of the steel reinforcement cage can be carried out. During hoisting construction, each section of the steel reinforcement cage is hoisted by adopting multiple points, so that the deformation caused by hoisting is reduced. The hoisting angle should be strictly controlled, and the included angle between the suspension arm and the lifting rope should be small-angle, so that the horizontal separation is reduced. The hoisting point at the top end of the steel reinforcement cage needs to be hoisted by a special hoisting tool, and the hoisting point at the root part of the steel reinforcement cage needs to be hoisted by two hoisting ropes. When the steel reinforcement cage is lifted, the top lifting point is lifted firstly, then the root lifting point is lifted, so that the steel reinforcement cage is changed from horizontal to inclined lifting, when the root of the steel reinforcement cage is completely separated from the ground, the top lifting point is quickly lifted to 90 degrees, then the root lifting point can be removed, and the steel reinforcement cage is vertically lifted into the hole and installed.
Further, referring to fig. 1, in the cement mixing pile process, a temporary steel casing 3 needs to be installed to protect the hole wall until the cement mixing pile process is completed, the temporary steel casing 3 is pulled out, and a permanent steel casing 1 is installed. The permanent steel casing 1 is a steel casing which is buried in a pile foundation hole and is not pulled out any more, and the temporary steel casing 3 is a steel casing which is temporarily used to protect the hole and is required to be pulled out in a subsequent step.
The embodiment adopts "mud dado + cement jump sheet pile + steel protects a section of thick bamboo" cement layer protection rapid hole forming technique, and the long diameter of 40m 2.5m pile foundation initial stage creeps into and down the steel protects a section of thick bamboo and is about 7 hours to the pore-forming time, can play fine guard action, can ensure construction quality and safety.
It should be noted that the slurry processing center used in this embodiment is a slurry processing device, and the slurry processing device is used as an environment-friendly pile foundation auxiliary machine device in modern foundation construction, and is increasingly applied to non-excavation pile foundation construction such as rotary drilling construction using a slurry wall protection process, pile foundation construction using a circular drilling process, continuous wall construction, slurry balance method shield construction, slurry push pipe construction, and the like. The equipment can effectively improve the pore-forming quality and the pore-forming work efficiency, shorten the pore-cleaning time, reduce the construction cost and reduce the drill sticking accidents. And from the perspective of environmental protection construction, the equipment realizes the recycling of slurry, so that the conventional waste slurry transportation and dumping treatment is changed into the solid-liquid separation of the waste slurry, and further the residue soil transportation treatment is realized. The method can greatly save the mud treatment cost in the construction process, greatly reduce the pollution of the mud in the construction process to the environment, and improve the modernization level of civilized construction and environment-friendly construction.
The above description is only a preferred embodiment of the present invention, but the present invention is not limited to the above embodiments, and the present invention shall fall within the protection scope of the present invention as long as the technical effects of the present invention are achieved by any similar or identical means.
Claims (7)
1. A composite protection rapid hole forming method for a pile foundation close to a subway viaduct is characterized by comprising the following steps:
a. measuring and lofting, surveying the geological structure and determining the position of a pile foundation;
b. drilling holes, and forming original holes at the pile foundation position;
c. establishing a slurry treatment center, establishing a slurry retaining wall on the side surface of an original hole, and carrying out a slurry performance parameter test, wherein the slurry treatment center establishes the slurry retaining wall with the slurry concentration of 1.1-1.3 before a permanent steel casing is installed, and establishes the slurry retaining wall with the slurry concentration of 1.03-1.1 after the permanent steel casing is installed;
d. the cement mixing pile adopts a two-spraying four-stirring process, the two-spraying four-stirring process is a twice stirring process adopted at each stirring position, each time of circulation comprises a first spraying process and a second stirring process, cement is sprayed once, the stirring process refers to the stirring operation in the process that the cement mixing pile extends into a covering layer or is pulled out of the covering layer, the mixing pile extends into the covering layer and is pulled out each time, the mixing pile carries out twice stirring work, the cement is sprayed out and pulled out simultaneously in the process that the mixing pile extends into the covering layer, one-spraying two-stirring process is completed once, the operations are continuously carried out twice at the same position, the cement is sprayed into a soil body by using a mixing pile machine and is fully;
e. embedding a permanent steel pile casing;
f. finishing and cleaning the hole;
g. processing and placing a reinforcement cage;
h. and (5) pouring underwater concrete.
2. The method for rapidly forming the hole on the composite type protective pile foundation of the viaduct adjacent to the subway as claimed in claim 1, wherein in step d, the cement mixing pile is driven through the silt layer and the sand layer, and the pile end of the cement mixing pile reaches the strongly weathered mudstone.
3. The method for rapidly forming the hole on the composite type protective pile foundation of the viaduct adjacent to the subway according to claim 1, wherein a single-row deep cement mixing pile is adopted in the step d.
4. The method as claimed in claim 1, wherein in step e, after positioning by using a bidirectional control positioning method, a permanent steel casing is embedded and fixed, and the permanent steel casing is sleeved into the original hole along the slurry retaining wall.
5. The method as claimed in claim 1, wherein the permanent steel casing is embedded into the original hole in a self-advancing or static pressure manner.
6. The method for rapidly forming the hole on the pile foundation of the viaduct adjacent to the subway according to claim 1, wherein in the step b, whether the center of the calibration drill is coincident with the center of the pile foundation position before drilling is performed.
7. The method for rapidly forming the hole in the combined type protection manner of the pile foundation of the viaduct adjacent to the subway according to claim 1, wherein the step f further comprises detecting the hole depth and the sediment thickness.
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