CN113981955A

CN113981955A - Construction method of test pile

Info

Publication number: CN113981955A
Application number: CN202111288282.6A
Authority: CN
Inventors: 许波; 邓广玉; 岺海津; 刘金宝; 张立福
Original assignee: China Coal Jiangnan Construction Development Group Co ltd
Current assignee: China Coal Jiangnan Construction Development Group Co ltd
Priority date: 2021-11-02
Filing date: 2021-11-02
Publication date: 2022-01-28

Abstract

The invention relates to the field of buildings, in particular to a construction method of a test pile. In the application, a pile foundation is formed by adopting a rotary drilling machine, and a damping steel pipe (a rubber damping layer is adhered to the outer side of the steel pipe) is wrapped outside an engineering pile reinforcement cage, so that the vibration damping of the pile foundation is realized; meanwhile, an industrial grease lubricating layer is brushed outside the rubber layer, and a PVC protective film is wrapped outside the grease lubricating layer, so that the aim of reducing the frictional resistance (drag reduction) of the foundation to the pile side is fulfilled, the sinking of the subway tunnel caused by pile foundation settlement is reduced, and the safety of the subway is ensured. And placing the manufactured reinforcement cage into the drilled hole, and pouring concrete. For the vibration reduction efficiency of the vibration reduction rubber layer, when the disturbance frequency of subway vibration at the pile body is 20Hz, the vibration reduction efficiency of the rubber layer on the outer side of the engineering pile is 54 percent; and the damping efficiency increases with the increase of the disturbance frequency, and is 97% when the disturbance frequency is 100 Hz.

Description

Construction method of test pile

Technical Field

The invention relates to the field of buildings, in particular to a construction method of a test pile.

Background

Subway operation, vehicle load all produce the shock wave, all produce different influences to the ground basis, and then influence superstructure normal use and produce serious secondary disaster. At present, basic earthquake-proof research is mainly started from the perspective of an earthquake-proof structure, the traditional earthquake-proof structure system mainly enhances earthquake-proof performance by improving the self rigidity and ductility of the structure, but the structural rigidity is improved once, so that the earthquake-proof performance is facilitated, the structure ductility is improved singly, the energy consumption capacity of the structure can be enhanced, the inertia force is increased, the structure absorbs more energy, adverse effects can be generated on the higher condition of a building, such as the shaking of a top floor, serious noise and the like.

Disclosure of Invention

In order to solve the problems, the invention provides a construction method of a test pile, when the disturbance frequency of subway vibration at a pile body is 20Hz, the vibration reduction efficiency of an outer rubber layer of an engineering pile is 54 percent; and the damping efficiency increases with the increase of the disturbance frequency, and is 97% when the disturbance frequency is 100 Hz.

In order to achieve the purpose, the invention adopts the technical scheme that: a construction method of a test pile comprises the following steps:

step 1: driving a special full-rotation sleeve by a full-rotation drilling machine, and drilling the full-rotation sleeve into a specified elevation;

step 2: drilling the full-rotation sleeve by a rotary drilling rig to take earth, and forming a first pile hole;

and step 3: taking out the full-rotation sleeve, and placing the pile casing in the first pile hole by the full-rotation drilling machine so as to replace the position of the full-rotation sleeve;

and 4, step 4: the rotary drilling rig drills into the protective cylinder and continues to dig downwards, and the rotary drilling rig takes earth to the height of the cylinder bottom of the damping cylinder and forms a second pile hole communicated with the first pile hole;

and 5: lowering the damping cylinder to the second pile hole;

step 6: grouting between the second pile hole and the damping cylinder through a grouting guide pipe, and sleeving a concrete protective layer on the outer wall of the damping cylinder;

and 7: the rotary drilling rig drills into the damping cylinder and continues to dig downwards, and takes soil to the designed pile bottom elevation to form a third pile hole communicated with the second pile hole;

and 8: lowering the reinforcement cage to the third pile hole, wherein the bottom of the reinforcement cage is level with the bottom elevation of the third pile hole, and the top of the reinforcement cage is level with the top of the damper cylinder;

and step 9: and pouring concrete into the first pile hole, the second pile hole and the third pile hole.

Further, the shock attenuation section of thick bamboo is including outsourcing steel pipe, rubber shock absorber layer, PVC protection film, and wherein rubber shock absorber layer passes through the lateral wall of viscose layer parcel at the outsourcing steel pipe, and the even coating of lateral wall of rubber shock absorber layer has the grease lubricant film, and the PVC protection film passes through the lateral wall of grease lubricant film parcel at rubber shock absorber layer.

Furthermore, the damping cylinder the bottom of outsourcing steel pipe extends outside the rubber shock absorber layer and constitutes the steel pipe bottom, and the lateral wall welding of this steel pipe bottom has a plurality of supporting shoes, and this supporting shoe supports the bottom at second stake hole.

Further, the top of outsourcing steel pipe extends outside the rubber damper layer and constitutes the steel pipe top, and a plurality of adjustment hole has been seted up to the lateral wall on this steel pipe top along its circumference, and all equips with the nut in every adjustment hole, and this nut all equips with the bolt, realizes adjusting damper cylinder's straightness that hangs down through adjusting bolt.

Further, between step 2 and step 3, there is also step 2 a: and filling slurry or backfill soil into the first pile hole.

And further, a step 7a is also included between the step 7 and the step 8, wherein the third pile hole is subjected to hole cleaning treatment by adopting a reverse circulation hole cleaning process, the density of slurry within 500mm of the bottom of the hole is enabled to be less than 1.10g/m, the sand content is less than or equal to 2%, the viscosity of the funnel is less than or equal to 18s, and the sediment is not more than 50 mm.

Further, in step 2, the full rotary sleeve is taken out by a jack and a crane.

The invention has the beneficial effects that: in the application, a pile foundation is formed by adopting a rotary drilling machine, a damping steel pipe (the length of the steel pipe is 19.15m) is coated outside an engineering pile reinforcement cage, and a rubber damping layer with the thickness of 30-40 mm is adhered outside the coated steel pipe, so that the vibration damping of the pile foundation is realized; meanwhile, an industrial grease lubricating layer is brushed outside the rubber layer, and a PVC protective film is wrapped outside the grease lubricating layer, so that the aim of reducing the frictional resistance (drag reduction) of the foundation to the pile side is fulfilled, the sinking of the subway tunnel caused by pile foundation settlement is reduced, and the safety of the subway is ensured. And placing the manufactured reinforcement cage into the drilled hole, and pouring concrete. Theoretical research and computational analysis show that the vibration reduction efficiency of the rubber layer on the outer side of the engineering pile is 54% when the disturbance frequency of subway vibration at the pile body is 20 Hz; and the damping efficiency increases with the increase of the disturbance frequency, and is 97% when the disturbance frequency is 100 Hz. And for the vibration reduction effect of the pile foundation vibration reduction defense line, according to the scientific research result, when the thickness of the rubber layer is 30mm, the vibration reduction effect can meet the requirement of the detection index; before actual construction, a single-pile vibration damping test is carried out according to different rubber layer thicknesses (35mm/45mm), if the target value is not reached, the thickness of the vibration damping rubber layer can be increased until the first-stage detection meets the index value (the daytime vibration level is not more than 75dB, and the nighttime vibration level is not more than 72dB), and according to the test result, the rubber layer thickness meeting the requirement is selected to carry out comprehensive engineering pile construction.

Drawings

FIG. 1 is a schematic view of the bottom layer of a test pile hole.

Fig. 2 is a working principle diagram of step 1 of the pile testing process.

Fig. 3 is a working principle diagram of step 2 of the pile testing process.

Fig. 4 is a working principle diagram of step 3 of the pile testing process.

Fig. 5 is a working principle diagram of step 4 of the pile testing process.

Fig. 6 is a working principle diagram of steps 5-6 of the pile testing process.

Fig. 7 is a working principle diagram of step 7 of the pile testing process.

Fig. 8 is a working principle diagram of steps 8-9 of the pile testing process.

Fig. 9 is a structural schematic view of a shock-absorbing cylinder.

Fig. 10 is an enlarged schematic view of the structure at I in fig. 9.

Fig. 11 is a schematic position diagram between a subway tunnel and a plurality of test piles.

The reference numbers illustrate: 1. a full rotation sleeve; 11. a first pile hole; 12. a second pile hole; 13. a third pile hole; 2. protecting the cylinder; 3. a damper cylinder; 31. steel pipes are wrapped; 32. an adhesive layer; 33. a rubber shock-absorbing layer; 34. a grease lubrication layer; 35. a PVC protective film; 36. a concrete protective layer; 37. a support block; 4. and (4) a reinforcement cage.

Detailed Description

Referring to fig. 1-11, in the present embodiment, during the pile testing process, a geological profile needs to be investigated, and according to the drilling disclosure data, the ground rock and soil layer is divided into the following types from top to bottom: artificial filling layer, washing layer, residual layer and weathered rock containing conglomerate of three water groups, Kangle section (K2S1) of chalk system. The following are now assigned:

artificial filling <1 >: the artificial filling layer disclosed by the field mainly comprises miscellaneous filling soil and partially plain filling soil. The plain filling soil is mainly grey brown, loose, slightly compacted locally and slightly wet, mainly comprises cohesive soil, sand and the like, and the top of the plain filling soil contains a small amount of broken stones and a concrete pavement. The miscellaneous fill is in miscellaneous color, loose to slightly compacted and slightly wet, mainly comprises concrete, broken stone and clay, and is filled with a small amount of bricks and domestic garbage.

The layer is widely distributed, all the drill holes are exposed, the layer thickness is 1.00-4.60 m, the average thickness is 2.99m, the layer top buried depth is 0.00-0.00 m (the elevation is 7.02-9.81m), and the layer bottom buried depth is 1.00-4.60 m (the elevation is 3.64-7.52 m). The filling soil in the field is formed by artificial filling, and the filling age of the old filling soil at the lower part exceeds 10 years except for newly demolished filling bricks at the surface layer.

Powdery clay layer <2-1 >: mainly brown yellow and gray, plasticity as main, general viscosity, moderate toughness and dry strength, mainly composed of sticky grains and powder grains, and containing a small amount of quartz grains. The layer thickness is 0.80-6.00 m, the average thickness is 2.77m, the layer top buried depth is 2.60-5.40 m (elevation 3.11-6.96 m), and the layer bottom buried depth is 3.80-9.50 m (elevation-2.33-6.01 m).

Mucky soil layer <2-2 >: grayish black, gray, fluid plastic, local soft plastic and slightly fishy smell, mainly comprises sticky particles and powder particles, has uniform soil texture, is sticky and smooth, contains organic matters, locally contains sand grains, has nonuniform soil texture of the layer, and locally contains powdery clay and silt. The layer thickness is 0.80-2.90 m, the average thickness is 1.69m, the layer top buried depth is 1.50-6.00 m (elevation is 2.99-6.77 m), and the layer bottom buried depth is 2.70-8.40 m (elevation is-1.37-5.02 m).

Medium-coarse sand layer <2-3 >: grayish yellow, saturated, slightly dense to medium dense, poor gradation, quartz particles as the component, and a small amount of sticky particles. The layer thickness is 0.60-3.90 m, the average thickness is 1.97m, the layer top buried depth is 1.00-9.20 m (elevation-1.07-7.52 m), and the layer bottom buried depth is 3.00-10.50 m (elevation-2.78-5.52 m).

Residual powdery clay layer <3 >: the local part is silty soil which is brownish red, brownish yellow and hard plastic, has general viscosity and moderate toughness and dry strength, mainly consists of sticky grains and powder grains, contains a small amount of quartz grains and is formed by residual conglomerate-containing sandstone. The layer thickness is 1.00-10.20 m, the average thickness is 3.44m, the layer top buried depth is 2.30-8.40 m (elevation-0.28-6.29 m), and the layer bottom buried depth is 4.50-14.10 m (elevation-6.10-3.67 m).

Fully weathered gravel-containing sandstone <4-1 >: the rock is brownish red, the rock is severely weathered, the original rock structure is destroyed, the rock core is hard soil, and the rock core is easy to disperse after being soaked in water and softened. Exposing the layer thickness to be 0.70 to 8.50m, the average thickness to be 3.69m, the layer top buried depth to be 2.40 to 11.10m (elevation-3.28 to 6.00m), the layer bottom buried depth to be 5.00 to 16.70m (elevation-8.98 to 3.22m)

Strongly weathered gravel-containing sandstone <4-2 >: the rock is mainly brownish red, the weathering of the rock is strong, most of the original rock tissue structure is destroyed, the joint fracture develops, the rock is half-rock half-soil-shaped and is crushed by soil, the rock is extremely soft-soft, is dehydrated and cracked, is easy to soften when meeting water, is easy to be broken by hammering, is dumb by hammering, and is locally rock pillar-shaped and partially weathered. All the drill holes are disclosed, the layer thickness is 0.40-38.40 m, the average thickness is 7.84m, the layer top buried depth is 2.40-51.00 m (elevation-43.25-minus 9.61m), and the layer bottom buried depth is 6.00-55.00 m (elevation-46.48-minus 17.45 m).

Weathered gravel-containing sandstone <4-3 >: brownish red, partial destruction of original rock tissue structure, sand-shaped structure, layered structure, argillaceous cementation, local argillaceous calcareous cementation, crack development, soft rock, and exposure of all drilled holes, wherein the thickness of the exposed layer is 0.60-27.90 m, the average thickness is 5.76m, the buried depth of the top of the layer is 6.00-54.00 m (elevation-46.25-17.18 m), and the buried depth of the bottom of the layer is 7.60-59.00 m (elevation-50.29-0.52 m).

Slightly weathered gravel-containing sandstone <4-4 >: brownish red, undamaged original rock tissue structure, sand-shaped structure, layered structure, argillaceous cementation, partial argillaceous cementation, fracture development and soft rock quality. All the drill holes of the layer are exposed, and are not drilled through, the thickness is 1.00-28.35 m, the average thickness is 14.42m, the buried depth of the top layer is 14.40-50.00 m (the elevation is-50.29-minus 6.11m), and the buried depth of the bottom layer is 20.00-72.17 m (the elevation is-63.88-minus 11.60 m).

According to the water-rich condition and water permeability of the stratum, the stratum of the site is evaluated as follows:

1. artificial fill layer <1 >: the field is distributed with miscellaneous filling soil, local plain filling soil, loose to slightly compacted shape, and medium-strong stratum permeability.

2. Powdery clay layer <2-1 >: the ground is distributed with a plastic clay layer which mainly comprises clay grains and powder grains, and has a small amount of quartz grains and a weak water permeable layer with poor water-rich property.

3. Mucky soil layer <2-2 >: the sludge layer of the field is widely distributed, is in a flow-plastic-soft-plastic shape, has uniform soil quality, locally contains a small amount of fine silt, shell fragments and the like, and is a micro-permeable layer.

4. Medium-coarse sand layer <2-3 >: the coarse sand layer in the field is distributed locally, is slightly-medium dense, has better water-rich property and stronger stratum permeability, and is a strong permeable layer.

5. Residual silty clay <3>, total weathering gravel-containing sandstone layer <4-1 >: the water-permeable floor is distributed sporadically in a hard plastic-hard shape, mainly comprises sticky particles and powder particles, locally contains a small amount of quartz particles, is softened when meeting water, has poor water-rich property and is a weak water-permeable layer.

6. 4-2 parts of strongly weathered gravel-containing sandstone and 4-3 parts of moderately weathered argillaceous siltstone: the bed rock crack of the layer in the field develops slightly, the permeability of underground water in the bed rock is weak, and the water-rich property is weak.

4-4 parts of slightly weathered gravel-containing sandstone layer, no fracture development, and weak permeability and water-rich property of underground water in bedrock.

Taking syz2 as an example, the predicted pile position formation condition is shown in fig. 1:

the invention relates to a construction method of a test pile, which comprises the following steps:

step 1: driving the special full-rotation sleeve 1 through a full-rotation drilling machine, and drilling the full-rotation sleeve 1 into a specified elevation;

step 2: drilling the full-rotation sleeve 1 by a rotary drilling rig to take earth, and forming a first pile hole 11;

and step 3: taking out the full-rotation sleeve 1, and placing the pile casing 2 in the first pile hole 11 by the full-rotation drilling machine so as to replace the position of the full-rotation sleeve 1;

and 4, step 4: the rotary drilling rig drills into the protective cylinder 2 and continues to dig downwards, and the rotary drilling rig takes earth to the height of the cylinder bottom of the damping cylinder 3 and forms a second pile hole 12 communicated with the first pile hole 11;

and 5: lowering the damper cylinder 3 to the second pile hole 12;

step 6: grouting is carried out between the second pile hole 12 and the damper cylinder 3 through a grouting guide pipe, and a concrete protective layer 36 is sleeved on the outer wall of the damper cylinder 3;

and 7: the rotary drilling rig drills into the shock absorption cylinder 3 and continues to dig downwards, the rotary drilling rig takes earth to the designed pile bottom elevation and forms a third pile hole 13 communicated with the second pile hole 12;

and 8: lowering the reinforcement cage 4 to the third pile hole 13, wherein the bottom of the reinforcement cage 4 is flush with the elevation of the bottom of the third pile hole 13, and the top of the reinforcement cage 4 is flush with the top of the damper cylinder 3;

and step 9: and pouring concrete into the first pile hole 11, the second pile hole 12 and the third pile hole 13.

In the embodiment, the full-casing rotary drilling machine is a novel drilling machine which integrates full-hydraulic power and transmission and electromechanical-hydraulic combined control. The construction speed is 8-10 times of that of other construction aspects under the same condition, the pile quality is higher than the national current construction acceptance standard, the excellent scientificity and advancement of the Bernout construction technology are shown, and the application prospect is very wide. The full rotation is a novel drilling machine which integrates full hydraulic power, transmission and electromechanical-hydraulic combined control. The drilling technology is novel, environment-friendly and efficient. The research of the brand-new process construction method succeeds, the construction of pile foundations of various complex strata such as cobble, boulder stratum, karst cave-containing stratum, thick quicksand stratum, strong necking stratum, huge thick stone-filling layer and the like is realized for constructors, and in addition, the construction of cast-in-place piles, replacement piles and underground continuous walls and the possibility of barrier-free penetration of pipe jacking and shield tunnels through various pile foundations can be realized under the condition that barriers such as pile pulling, reinforced concrete structures and the like are not removed.

The full casing drilling machine is characterized in that:

(1) no noise and no vibration;

(2) the slurry is not used, the processing, storage and transportation of the slurry are avoided, and the operation surface is clean;

(3) soil and lithologic characteristics can be visually judged during excavation, and for the end-supported pile, the pile length can be conveniently determined on site;

(4) the excavating speed is high and can reach about 14 m/h for general soil;

(5) the drilling depth is large, and the deepest depth reaches 143.8m according to the soil layer condition;

(6) the verticality of the formed hole is convenient to master, and the verticality can be accurate to 1/500;

(7) because the drilling machine is a full-casing drilling machine, the hole wall can not collapse, and the hole forming quality is high;

(8) the diameter of the formed hole is standard, the filling coefficient is very small, and 13% of concrete can be saved compared with other hole forming methods;

(9) the hole cleaning is thorough, the speed is high, and the drilling slag at the bottom of the hole can be cleaned to about 3.0 cm;

(10) the drilling machine is self-propelled, and is convenient for field movement.

Meanwhile, the rotation of a rotating device of the full-rotation drilling machine is utilized, so that the frictional resistance between the full-rotation sleeve 1 and the soil layer is greatly reduced, the full-rotation sleeve is pressed in while rotating, and the rotary excavator is utilized to drill and take the soil until the full-rotation sleeve 1 is about 1m below the strongly weathered rock surface.

Further, the full-rotation sleeve 1 comprises a first section of sleeve and a standard section of sleeve, wherein a cutting edge is arranged on the extension of the lower end of the first section of sleeve, and a first fixing pin hole is formed in the upper end of the first section of sleeve; the lower opening of the first section of the sleeve is provided with a cutting edge, so that the first section of the sleeve is convenient to sink and drill, and the upper end of the first section of the sleeve is provided with a fixed pin hole, so that the first section of the sleeve is convenient to be connected with a standard; the upper and lower both ends of standard festival sleeve pipe all are provided with the fixed pinhole of second, and standard festival sleeve pipe: the upper end and the lower end are provided with fixing pin holes, so that the extension and the disassembly are convenient; wherein the first fixing pin hole of the first section of sleeve pipe is mutually assembled with the second fixing pin hole at one end of the standard section of sleeve pipe, and the second fixing pin hole at the other end of the standard section of sleeve pipe is assembled with the full-rotary drilling machine.

In the step 2, the full-slewing drilling machine only uses a special first section of sleeve (the thickness of the wall of the sleeve is 60mm, the extension of a tool bit is 10mm, and the total thickness is 70mm) to drill in place (the thickness of the steel pipe enters a strongly weathered surface by about 1m), the protective cylinder 2 (the thickness of the wall of the steel pipe is 30mm) is replaced, in order to avoid the difficulty in removing the sleeve, in the step 2, the full-slewing sleeve 1 is taken out through a jack and a crane, and the full-slewing drilling machine is prevented from being removed in a returning mode. Also before replacing the casing 2, i.e. between step 2 and step 3, there is a step 2 a: and (3) filling slurry or backfill in the first pile hole 11 to avoid hole collapse when the first section of casing is pulled out. Simultaneously, the shock absorption pipe is put down after the drill hole is dug to the shock absorption pipe bottom elevation, the shock absorption cylinder 3 the bottom of the outer-coated steel pipe 31 extends out of the rubber shock absorption layer 33 and forms the steel pipe bottom end, the outer side wall of the steel pipe bottom end is welded with a plurality of supporting blocks 37, and the supporting blocks 37 abut against the bottom of the second pile hole 12. Wherein 8 supporting blocks 37 with the thickness of 20mm are oppositely supported and welded at the bottom of the shock-absorbing cylinder 3 and are used for supporting the whole shock-absorbing cylinder 3; meanwhile, in this embodiment, the top of the outer-coated steel tube 31 extends out of the rubber shock-absorbing layer 33 and forms a steel tube top end, the outer side wall of the steel tube top end is provided with a plurality of adjusting holes along the circumferential direction, each adjusting hole is internally provided with a nut, each nut is provided with a bolt, and the adjustment of the verticality of the shock-absorbing cylinder 3 is realized through the adjusting bolts. Wherein 8 alignment holes are evenly distributed on the top, the aperture is 60mm, 58 x 35 x 32 nuts are welded into the alignment holes, the nuts are flush with the inner side of the steel pipe, and the verticality of the steel pipe is adjusted by using high-strength bolts. And then grouting the outer side of the shock absorption pipe to form a protective layer for the rubber pad made of the shock absorption material (basically protecting the subway tunnel after grouting is finished), drilling a hole by using a rotary excavating machine to the designed pile bottom elevation, placing the reinforcement cage 4, and finally pouring underwater concrete.

Further, damper cylinder 3 includes outsourcing steel pipe 31, rubber shock absorber layer 33, PVC protection film 35, and wherein rubber shock absorber layer 33 passes through viscose layer 32 parcel at the lateral wall of outsourcing steel pipe 31, and the even coating of lateral wall of rubber shock absorber layer 33 has grease lubricant layer 34, and PVC protection film 35 passes through grease lubricant layer 34 parcel at the lateral wall of rubber shock absorber layer 33.

Further, a step 7a exists between the step 7 and the step 8, wherein the third pile hole 13 is subjected to hole cleaning treatment by adopting a reverse circulation hole cleaning process, the density of slurry within 500mm of the bottom of the hole is smaller than 1.10g/m, the sand content is smaller than or equal to 2%, the viscosity of the funnel is smaller than or equal to 18s, and the sediment is not larger than 50 mm.

Hole cleaning requirements are as follows:

(1) during the hole cleaning process of the cast-in-place pile, slurry is continuously replaced until underwater concrete is poured. Before concrete is poured, the density of slurry within 500mm of the bottom of a hole is less than 1.10g/m, the sand content is less than or equal to 2%, the viscosity of a funnel is less than or equal to 18s, sediment is not more than 50mm, meanwhile, the slurry proportion of a poured pile is determined according to the situation of a field stratum and the situation of hole wall stability, and measures for maintaining the hole wall stability are taken in a soil layer which is easy to leak slurry;

(2) for a sandy soil layer and a sand cobble layer with poor soil quality, the specific gravity of the hole bottom slurry after hole cleaning is 1.15-1.25 (g/cm 3);

(3) the thickness of the sediment at the bottom of the hole after hole cleaning is not more than the designed specified value of 50 mm. And (4) re-measuring the thickness of the sediments before pouring the underwater concrete, cleaning the holes again when the sediments exceed the specification, and pouring the underwater concrete after the sediments are qualified. The engineering adopts a reverse circulation hole cleaning method:

the above embodiments are merely illustrative of the preferred embodiments of the present invention, and not restrictive, and various changes and modifications to the technical solutions of the present invention may be made by those skilled in the art without departing from the spirit of the present invention, and the technical solutions of the present invention are intended to fall within the scope of the present invention defined by the appended claims.

Claims

1. A construction method of a test pile is characterized by comprising the following steps:

step 1: driving the special full-rotation sleeve by a full-rotation drilling machine, and drilling the full-rotation sleeve to a specified elevation;

and 5: lowering the damping cylinder to the second pile hole;

and 8: lowering the reinforcement cage 4 to the third pile hole, wherein the bottom of the reinforcement cage 4 is level with the elevation of the bottom of the third pile hole, and the top of the reinforcement cage 4 is level with the top of the shock-absorbing cylinder;

2. The construction method of the test pile according to claim 1, wherein the damping cylinder comprises an outer-coated steel pipe, a rubber damping layer and a PVC protective film, wherein the rubber damping layer is wrapped on the outer side wall of the outer-coated steel pipe through an adhesive layer, the outer side wall of the rubber damping layer is uniformly coated with a grease lubricating layer, and the PVC protective film is wrapped on the outer side wall of the rubber damping layer through the grease lubricating layer.

3. The construction method of a test pile according to claim 2, characterized in that: the damping cylinder the bottom of outsourcing steel pipe extends outside the rubber shock absorber layer and constitutes the steel pipe bottom, and the lateral wall welding of this steel pipe bottom has a plurality of supporting shoes, and this supporting shoe supports the bottom at second stake hole.

4. The construction method of a test pile according to claim 3, characterized in that: the top of outsourcing steel pipe extends outside the rubber damper layer and constitutes the steel pipe top, and a plurality of adjustment hole has been seted up to the lateral wall on this steel pipe top along its circumference, and all equips with the nut in every adjustment hole, and this nut all equips with the bolt, realizes adjusting damper cylinder's straightness that hangs down through adjusting bolt.

5. The construction method of a test pile according to claim 1, characterized in that: in between step 2 and step 3, there is also step 2 a: and filling slurry or backfill soil into the first pile hole.

6. The construction method of a test pile according to claim 1, characterized in that: and 7a, performing hole cleaning treatment on the third pile hole by adopting a reverse circulation hole cleaning process between the step 7 and the step 8, wherein the density of slurry within 500mm of the bottom of the hole is smaller than 1.10g/m, the sand content is smaller than or equal to 2%, the viscosity of the funnel is smaller than or equal to 18s, and the sediment is not larger than 50 mm.

7. The construction method of a test pile according to claim 1, characterized in that: in step 2, the fully-revolving sleeve is taken out by the jack and the crane.