CN111335312A - Rock-entering construction process for large-diameter lock catch steel pipe pile - Google Patents

Abstract

The invention discloses a large-diameter lock catch steel pipe pile rock entering construction process, which comprises the following steps: pre-drilling holes by rotary drilling; making a steel pipe pile; sinking the steel pipe pile to 30cm above the rock surface; rotary drilling a pile core and taking out soil; hammering the down-hole into the rock for 3 m; after the pile core is drilled in a rotary drilling manner and soil is taken out, slowly placing the hammer head into the pile core through a drill rod, reversely rotating the down-the-hole hammer in the pile to blow off the residual loose soil layer in the pile, and after the hammer head contacts an inner hoop of the pile and generates a crisp sound, positively rotating to open the wing, and at the moment, fully opening 4-5 air compressors, wherein the air pressure is not less than 1.4Mpa, and the rotating speed is 3-4 r/min; the steel pipe pile synchronously follows when the hammer head drills, and when the blown slag is changed into grey rock powder from yellow mud slag and the sinking speed is obviously reduced, the height of the steel pipe pile entering the rock top is recorded until the down-the-hole hammer enters the rock by 3 m. The invention solves the problem that the pore diameter of the formed hole is larger than the pile diameter, and the steel pipe pile can follow along with the down-the-hole hammer, has high rock entering speed, and can not cause the conditions of drill hole collapse and repeated crushing.

Description

Rock-entering construction process for large-diameter lock catch steel pipe pile

Technical Field

The invention relates to a steel pipe pile rock-entering construction process, in particular to a large-diameter lock catch steel pipe pile rock-entering construction process.

Background

The operation of locking and buckling the steel pipe pile into the rock is carried out on the high-strength rock foundation, and the conventional construction method in China mainly comprises two methods, namely, the traditional impact drilling punching method is used, but the aperture after punching is smaller than the pile diameter, so that the steel pipe pile cannot be vibrated and sunk; and secondly, a rotary drilling pre-drilling method is adopted, the rotary drilling efficiency in a rock stratum is very slow, 20 hours are required for 3m rock entering, and great uncertainty exists, and a reaming bit is required to ream again after the rock stratum is drilled, so that the progress requirement cannot be met, and the gear wheel consumption is high, and the cost consumption is huge. .

The rock entering construction process which is larger than the pile diameter in pore-forming diameter, does not need extra hole expansion and is high in rock entering speed is urgently needed.

Disclosure of Invention

The invention aims to solve the technical problem of providing a rock entering construction process which has the advantages that the diameter of a formed hole is larger than the diameter of a pile, no hole is required to be expanded, and the rock entering speed is high.

In order to achieve the purpose, the technical scheme of the invention is as follows:

the large-diameter lock catch steel pipe pile rock entering construction process is characterized in that: the construction process comprises the following steps:

(1) pre-drilling hole by rotary drilling

The stratum of the project contains more pebble layers and large boulders, and after typical construction, the steel pipe pile cannot be directly vibrated and sunk in place, and pre-formed holes need to be replaced and filled. And (3) performing pre-hole construction by adopting a rotary drilling rig, wherein the diameter of the pile casing needs to cover the whole lock catch steel pipe pile in order to ensure that the steel pipe pile can smoothly vibrate and sink in place.

After comparison, sand-soil mixture is preferably used for replacing the filler, and both broken stones and medium coarse sand are easy to cause pile sinking difficulty or pile head deformation.

(2) Steel pipe pile making pile

Because the rock breaking resistance and the friction force between adjacent lock catches need to be overcome in the process of entering the rock and sinking the pile, the straightness of the lock catches needs to be checked and controlled to be 1cm during pile manufacturing, so that the equipment damage caused by continuous striking of the follow-in ring due to overlarge lock catch friction force after the rock is broken by the down-the-hole hammer is reduced; (3) steel pipe pile vibration sinking

After the steel pipe pile manufacturing is finished, the steel pipe pile is vibrated and sunk into the preformed hole, and a crawler crane and a vibration hammer are used for vibrating and sinking the steel pipe pile;

(4) dig and bore stake core and draw soil soon

The method comprises the following steps that a rotary drilling rig is adopted for digging soil for a pile core of the steel pipe pile, the lifting height of the rotary drilling rig is adjustable, and the adjustable range is 5-10 m, so that the technical scheme shows that the problem that certain errors occur between the actual rock surface height and the rock surface of a drawing through the rotary drilling rig with the adjustable lifting height is solved;

(5) down-the-hole hammer into rock

(5.1) lower down-the-hole hammer, open the wings

After the pile core of the rotary drilling pile is excavated, the down-the-hole hammer is shifted to an operation point, the hammer head is slowly put into the pile core through a drill rod, the down-the-hole hammer reversely rotates and sinks to prevent the wings from being clamped in the pile after being opened, at the moment, the liquid mud and the loose soil layer are mainly used in the pile, only 2-3 air compressors are started, all the air compressors are started after the hammer head of the down-the-hole hammer contacts with the inner hoop of the pile bottom and generates crisp sound, and the air pressure is not less than 1.4Mpa and the wings of the reaming hole are opened in the forward rotation mode. Due to the fact that broken stones exist in the backfilled sand, the broken stones blown out in the process of lowering the hammer body can block the exhaust duct, the situation can cause that the down-the-hole hammer can not make a sound normally after contacting with the pile bottom inner hoop, and the hammer head needs to be moved out of the duct to remove the broken stones and then lowered again;

(5.2) blowing slag and reaming, and self-following steel pipe pile

After the wing is opened, the wing rotates along with the hammer head, the crushed slag is discharged out of the pile through the exhaust hole of the hammer head, the steel pipe pile synchronously sinks along with the drilling of the hammer head, and the drilling amount of the hammer head is increased, and the follow-up amount of the steel pipe pile is increased; according to the technical scheme, the steel pipe pile is self-following, secondary vibration sinking of a vibration hammer is not needed, the working efficiency is high, the rock entering speed is high, and the situations of drill hole collapse and repeated crushing cannot occur;

and when the blown slag is changed from yellow mud slag into grey rock powder and the speed is obviously reduced, judging whether the steel pipe pile starts to enter the rock or not by combining the early-stage pre-hole forming data, recording the initial elevation after the steel pipe pile enters the rock, and continuously breaking the rock and blowing the slag until the preset rock entering depth is reached.

Further: in the step (5.1), the diameter and the ovality of the inner wall of the steel pipe pile are ensured to meet the requirement of smooth downward placement of the hammer head when the hammer head is placed, and the drill jamming phenomenon can be avoided.

Further: the bottom inner wall of the steel pipe pile is provided with a convex annular follow-up ring, the hammer head is provided with an annular groove, the annular follow-up ring is used for being clamped in the annular groove of the hammer head, the annular follow-up ring is matched with the annular groove to enable the steel pipe pile and the down-the-hole hammer to be concentric, the concentric steel pipe pile and the down-the-hole hammer can realize bottom expanding drilling and synchronous follow-up of the pipe pile, namely the steel pipe pile can be drilled and synchronously driven along with bottom expanding of the down-the-hole hammer.

Further: the wall thickness of circle is followed to the annular is greater than the diameter of tup in the steel-pipe pile and the diameter of steel-pipe pile inner wall diameter is poor, and from this technical scheme can know, adopts the annular of this specific wall thickness to follow the circle, can be so that the steel-pipe pile follow the ring through the annular and firmly with the annular groove connection on the tup, improve the stability of advancing simultaneously.

Further: the annular follow-up ring is made of Q345 steel, is high in strength and not easy to damage, and is not easy to fall off after being installed; compared with Q235 steel, the performance is much better.

Further: in the step (5.3), in the process of breaking rock and advancing by the down-the-hole hammer, if the advancing length of the hammer head is less than 5cm within 10 minutes, immediately stopping entering the rock, moving the down-the-hole hammer out of the pile, and checking whether equipment damage occurs or not; if the equipment is damaged, continuing to put the broken rock into footage after repairing; if the device is not damaged, it is checked whether there are other problems.

Further: the construction process also comprises the inspection of down-the-hole hammer equipment;

the hydraulic hammer equipment is checked after rock entering is completed, when the total station detects that the rock breaking depth reaches a preset depth, the hammer head is reversed, the wing fins are retracted, the drill rod is lifted, and if the drill jamming phenomenon occurs, the hammer head needs to be turned again to open the wing fins to be knocked in the air, then the wing fins are reversed again, retracted and lifted, so that the wing fins of the hammer head are completely retracted; after the hammer head is moved out of the pile, a mechanical manipulator checks whether the hammer head cracks, wing fractures and alloy spherical teeth on a hammer head bottom plate fall off or not so as to determine whether rock breaking can be continued or not; if the hammer head cracks and the wing is broken, replacing the hammer head and the wing; if the alloy beads at the bottoms of the hammer head and the wing fall to more than one fifth, the rock-entering effect of the down-the-hole hammer is affected, the hammer head and the wing alloy beads need to be replaced, damaged old alloy beads are removed through the spark discharger, and new alloy buttons are installed.

Further: the vertical central axis of the down-the-hole hammer is on the same straight line with the vertical central axis of the pile sinking, and the vertical central axis of the pile sinking is parallel to the lock catch; this application sets up the vertical central axis of down-the-hole hammer and the vertical center of pile sinking on a straight line, and is parallel with the vertical central axis of pile sinking and hasp, and it has solved the destruction that eccentric pile sinking caused the down-the-hole hammer to and eccentric removal sinks and brings bigger tip resistance, and the tup damages easily, follows up the problem that the circle drops easily. In general, after the verticality of the sunk pile exceeds 1%, a special-shaped pile needs to be manufactured to adjust the verticality of the pile, and because the steel pipe pile and the hammer body are synchronously sunk in the down-the-hole hammer construction process, the special-shaped pile only needs to be sunk under the condition of ensuring the freedom of the special-shaped pile, and the steel pipe pile cannot be sunk into the rock after being vibrated for a plurality of steel pipe piles at one time in advance.

Through the technical scheme, the invention has the beneficial effects that:

the invention has the advantages of high rock entering speed, high slag discharging wind speed, no need of secondary crushing, high work efficiency, larger pore-forming diameter than pile diameter, self-following of the pipe pile and no need of secondary vibration and sinking of a vibration hammer.

Drawings

FIG. 1 is a flow chart of a rock-entering construction process of a large-diameter lock catch steel pipe pile.

Detailed Description

In order to make the technical means, the creation characteristics, the achievement purposes and the effects of the invention easy to understand, the invention is further explained below.

Referring to fig. 1, the invention discloses a large-diameter lock catch steel pipe pile rock-entering construction process, which comprises the following steps:

(1) pre-drilling hole by rotary drilling

Pre-drilling holes are drilled by adopting an SANY360/365 rotary drilling machine, pre-drilling hole construction is carried out by the rotary drilling machine, the pre-drilling holes are determined according to parameters such as the diameter, the length and the like of the steel pipe pile, the construction mode of the rotary drilling machine is a conventional technology, and details are not repeated herein; carry out backfill sand and pile casing pull out after the pre-perforation, the diameter of the pile casing covers the whole lock catch steel pipe pile, the diameter of the pile casing in the application is 1200mm, of course, other diameters can be realized according to actual needs, and the redundant description is omitted here; according to the technical scheme, the pile casing covers the whole lock catch steel pipe pile, so that the problem that the follow-up pile sinking still encounters boulders can be effectively prevented.

In addition, according to the geological conditions of the construction area, if a large amount of boulders are contained in the geological area, the drill bits need to be specially reinforced except for the drill bits, the shoe teeth, the cutting teeth and the cone which are configured in a supernormal way, and a specific reinforcing mode is not described here.

(2) Steel pipe pile making pile

The inner diameter of the steel pipe pile is 988mm, the diameter of the upper part of the hammer head is 978mm, and the distance between the upper part of the hammer head and the inner wall of the steel pipe pile is only 10mm, so that the inner diameter of the steel pipe pile needs to be checked after pile manufacturing, and a drill jamming site is avoided; meanwhile, the wall thickness of the follow-up ring is 16mm, the distance between the bottom of the hammer head and the follow-up ring is only 10mm, and the inner diameter of the follow-up ring also needs to be checked after pile making; according to the technical scheme, the rock breaking resistance and the friction force between adjacent lock catches are overcome in the process of entering the rock and sinking the pile, otherwise, the situations that the inner hoop of the pile falls off, the hammer body is abraded, the pile cannot enter the rock smoothly and the like are easily caused; therefore, the straightness deviation of the lock catch is required to be checked and controlled to be smaller than 1cm during pile making, so that equipment damage caused by continuous striking of the follow-in ring due to overlarge friction force of the lock catch after rock breaking of the down-the-hole hammer is reduced; in order to reduce the influence of the locking friction force on the down-the-hole hammer-in rock as much as possible, the invention adopts a process of sinking piles one-in-rock, and is not influenced by the special-shaped piles under the condition, if the piles are uniformly sunk into the rock after being vibrated and sunk, the special-shaped piles or the condition with larger verticality deviation can not occur, otherwise, the condition that the inner hoops fall off or the hammer body is worn easily occurs.

(3) Steel pipe pile vibration sinking

Determining the pile sinking sequence of the steel pipe pile according to the down-the-hole hammer equipment, and selecting reasonable pile sinking equipment, which comprises the following specific steps: after the steel pipe pile is manufactured, the steel pipe pile is vibrated and sunk to a pre-hole forming position, in order to ensure that a down-the-hole hammer tooth expanding drill bit is smoothly opened, the elevation of the pile bottom needs to be strictly controlled, and the vibration and sinking of the steel pipe pile are stopped when the steel pipe pile reaches 30cm-50cm above the rock surface; the pile sinking equipment comprises a 180t crawler crane and a hydraulic vibration hammer; in addition, the diameter of the hole needs to be enlarged by combining a down-the-hole hammer, and the lock catch direction of the sunk pile is considered, so that collision between the reaming wing and the lock catch of the sunk steel pipe pile is avoided; because the diameter of the down-the-hole hammer is about 1050, the diameter exceeds the outer edge of the steel pipe pile by 15mm after hole forming, the female buckle is closer to the steel pipe pile after the male buckle and the female buckle are combined, so that the pile sinking needs to be carried out in the advancing direction of the pile sinking, and the lock catch of the sunk pile cannot be touched in the rock entering process.

In addition, if the friction force between the lock catches is large after the large batch of vibration-sinking steel pipe piles are subjected to vibration sinking, once the abnormal-shaped piles cannot normally enter the rock subsequently, the principle of vibration-sinking one pile and rock-entering one pile is adopted, the overall effect is basically consistent, and the repeated reworking problems that the drill bit is abraded and the lock catches cannot normally sink are reduced.

(4) Dig and bore stake core and draw soil soon

Adopt to dig soon and bore and dig the steel-pipe pile core and draw soil, the promotion height-adjustable who digs soon is 5 to 10 meters, and from this technical scheme knows, has solved the problem that actual rock face height can appear certain error with the drawing rock face through promoting height-adjustable's dig soon, and general error height is 5 to 10 meters, therefore dig the height-adjustable who bores soon and be 5 to 10 meters.

(5) Down-the-hole hammer into rock

(5.1) lower down-the-hole hammer, open the wings

In order to avoid the damage of the rotary drilling bit to the pile bottom heel feeding ring, the rotary drilling bit is used for digging soil which is about 50cm higher than the pile bottom, and the residual soil can be blown out by a down-the-hole hammer directly in the follow-up process. After the pile core of the rotary drilling pile is excavated, the down-the-hole hammer is shifted to an operation point, the hammer head is slowly put into the pile core through a drill rod, the down-the-hole hammer reversely rotates and sinks to prevent the wings from being clamped in the pile after being opened, at the moment, liquid mud and loose soil layers are mainly used in the pile, only 2-3 air compressors are required to be opened, all the air compressors (4-5 air compressors and 5 air compressors which are generally opened on site are determined mainly through air pressure, if the pile is shorter than 25m, 4 air compressors can be normally opened) after the hammer head of the down-the-hole hammer contacts an inner hoop at the bottom of the pile and generates crisp sound, and the air pressure is not less than 1.4Mpa, and the wings of the hole expanding are opened in a. Due to the fact that broken stones exist in the backfilled sand, the broken stones blown out in the process of lowering the hammer body can block the exhaust duct, the down-the-hole hammer can not make a sound normally after contacting with the pile bottom inner hoop under the condition, and the hammer head needs to be moved out to remove the broken stones outside the duct and then lowered again.

The air compressor is used as a power source of the down-the-hole hammer, compressed air is used for blowing and washing rock debris at the bottom of a hole and cooling a medium of a hammer head, the pressure of the air compressor meets the working requirement of the down-the-hole hammer impactor, and the rock debris can be discharged, so that the air compressor is comprehensively considered according to the working performance of the down-the-hole hammer, the aperture and the depth of a pile and other factors when being selected. The impact frequency and the impact power of the down-the-hole hammer impactor are both related to the air pressure, which is an important factor determining the impact power and thus is a main parameter influencing the drilling speed of the down-the-hole hammer, and the increase of the drilling speed and the increase of the air pressure are in a direct proportion relationship. Through practical conclusion, the impact frequency and the drilling speed of the down-the-hole hammer impactor can be ensured to be optimal when the air pressure is maintained to be more than 1.4 MPa.

(5.2) blowing slag and reaming, and self-following steel pipe pile

When the soil layer is broken and slag is blown, the steel pipe pile synchronously follows along with the hammer head while the hammer head drills, and the drilling amount of the hammer head and the following amount of the steel pipe pile are increased; according to the technical scheme, the steel pipe pile is self-following, secondary vibration sinking of a vibration hammer is not needed, the working efficiency is high, the rock entering speed is high, and the situations of drill hole collapse and repeated crushing cannot occur; when the blown slag is changed from yellow mud slag to gray rock powder and the speed is obviously reduced (because the down-the-hole hammer starts to expand the hole in a soil layer, the resistance is small, the sedimentation rate can reach 10-15 cm/min, once the down-the-hole hammer reaches the rock surface, the speed is reduced immediately, the speed is about 2-3 cm/min, whether the speed is obviously reduced is generally judged by observing 5cm sinking time through a measuring instrument), and whether rock entering is started is judged by combining the early pre-hole data (the rock entering is judged by the following three aspects, 1, the slag is obviously found to be rock slag, the rock slag can be judged by hand pinching, the rock slag is obviously different from sand, 2, the speed of 5cm sinking is observed through the measuring instrument, the speed can be obviously observed to be reduced, 3, the pre-hole rotary drilling has data, the rock surface is definitely below the pre-hole, once the elevation is lower than the, and if the pre-drilling hole bottom elevation is not reached, determining that the steel pipe pile does not start to enter the rock), recording the initial elevation after the steel pipe pile enters the rock, and continuing breaking the rock and blowing slag until the preset rock entering depth is reached. By adopting the rock-entering construction process, the time required for breaking the rock and entering the ruler for 3m at the rock strength of 100-120Mpa is 1-2 h; in the process of breaking rock and advancing by the down-the-hole hammer, if the advancing length of the hammer is less than 5cm in 10 minutes, immediately stopping entering the rock, moving the down-the-hole hammer out of the pile and checking whether equipment damage occurs or not; if the equipment is damaged, continuing to put the broken rock into footage after repairing; if the device is not damaged, it is checked whether there are other problems.

In addition, when the steel pipe pile enters the rock, the rock entering depth needs to be strictly controlled, once the rock entering depth exceeds the rock entering depth, the steel pipe pile body deforms after the lock catch enters the rock, and the situation that the hammer head cannot be smoothly pulled out can be caused, and if the situation occurs, the pile body can only be pulled out; in addition, the rock entry rate needs to be closely tracked, and the abnormality needs to be immediately stopped when being found.

According to the invention, the inner wall of the bottom of the steel pipe pile is provided with the protruded annular follow-up ring, the hammer head is provided with the annular groove, when the down-the-hole hammer breaks rock stratum and drills, the annular follow-up ring welded at the bottom of the pile is clamped by the annular groove on the hammer head, the steel pipe pile follows up the hammer head by the drilling amount, and the steel pipe pile follows up by the drilling amount, so that the situations of drilling collapse and repeated breaking can not occur; the annular follow-up ring and the annular groove are matched to enable the steel pipe pile and the down-the-hole hammer to be concentric, the concentric steel pipe pile and the down-the-hole hammer can realize bottom expanding drilling and synchronous follow-up of the pipe pile, namely the steel pipe pile can be expanded to drill and synchronously advance along with the down-the-hole hammer.

The annular follow-up ring is made of Q345 steel, is high in strength and not easy to damage, and is not easy to fall off after being installed; compared with Q235 steel, the performance is much better; moreover, the annular follow-up ring can also be made of other materials which have high strength, are not easy to damage and are not easy to fall off after installation, which is determined by manufacturers and is not described herein again.

The construction process also comprises the inspection of down-the-hole hammer equipment; the down-the-hole hammer equipment is checked after rock entering is completed, when the total station detects that the rock breaking depth reaches a preset depth (limited to 3m in the invention), an air compressor is closed, a drill rod is lifted, if the drill jamming phenomenon occurs, wings which are just opened by a hammer head need to be rotated to be empty and then rotated and lifted again, so that the wings of the hammer head are completely retracted, and small stones are prevented from being clamped between the hammer head and the wall of the steel pipe pile; after the hammer head is moved out of the pile, a mechanical operator checks whether the hammer head cracks or wings break or not and alloy spherical teeth on a bottom plate of the hammer head fall off so as to determine whether rock breaking can be continued; if the hammer head cracks and the wings break, the hammer head and the wings are replaced; if the alloy beads at the bottoms of the hammer head and the wing fall to more than one fifth, the rock-entering effect of the down-the-hole hammer is affected, the hammer head and the wing alloy beads need to be replaced, damaged old alloy beads are removed through the spark discharger, and new alloy buttons are installed.

In the invention, JB160A pile frames are adopted (by fixed processing)

The drill rod connects the single-shaft power head of the pile machine with the down-the-hole hammer) and the SANY360 rotary drilling rig (the drill driving cylinder is connected with the down-the-hole hammer through the fixed processing lining rod) as a pile frame to carry out down-the-hole hammer construction. When the steel pipe pile is a short pile, the JB160A walking pile frame has a height of 35m, and the reverse direction is avoidedThe efficiency can be improved by 25 percent by dismantling the drill rod again.

In the rock-entering process, because the internal friction reducing strips of the down-the-hole hammer are made of loss materials, the down-the-hole hammer is required to be detached for inspection every 15 or so rock-entering piles, if the wear of the friction reducing strips is not timely replaced, damage to a piston, a cylinder sleeve (chuck) and the like is easily caused, and after a hammer body is disassembled, the inner wall of the piston is polished and then new friction reducing strips are replaced; meanwhile, after long-time use, the fact that the using condition of the down-the-hole hammer is optimal and the abrasion is minimum when the using amount of the down-the-hole hammer lubricating oil is 15-20 liters per hour is found. According to the invention, the part of the bottom of the tubular pile, which is only 3m into rock, is not provided with the lock catch, the rock depth is strictly controlled, once the part is beyond the depth, the steel pipe pile body is deformed after the lock catch enters the rock, so that the condition that the hammer head cannot be smoothly pulled out can be caused, if the condition occurs, the pile body can be pulled out only, the condition that the deviation exists in the rock in site observation, the absolute accuracy cannot be achieved, and after the communication between the owner and a design institute, the length of the male buckle is reduced by 10cm, so that the condition that the down-the-hole hammer cannot be smoothly pulled out due to the fact that.

According to a common construction method, rotary drills are selected for rock entering construction, a gear drum is used for drilling embedded rocks for 3m, then a hydraulic hole expanding drill is used for expanding holes for 3m, the rock embedding work efficiency is 20h/3m, the hole expanding work efficiency is 10h/3m, namely 0.7 drill/stand/day, large uncertainty exists, 8 rotary drills need to be used for simultaneous operation according to the process, and the construction efficiency of 2 down-the-hole hammers can be achieved.

The foregoing shows and describes the general principles and broad features of the present invention and advantages thereof. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims (8)

1. The large-diameter lock catch steel pipe pile rock entering construction process is characterized in that: the construction process comprises the following steps:

(1) pre-drilling hole by rotary drilling

Pre-drilling construction is carried out by rotary drilling, the pre-drilled hole meets the installation requirement of the steel pipe pile, and the diameter of a protective cylinder of the pre-drilled hole covers the whole lock catch steel pipe pile;

(2) steel pipe pile making pile

Strictly controlling the roundness, the inner diameter and the straightness of the steel pipe pile, wherein the inner diameter of the steel pipe pile is not less than 980mm, and the straightness deviation of the lock catch is controlled within 1 cm;

(3) steel pipe pile vibration sinking

After the steel pipe pile manufacturing is finished, the steel pipe pile is vibrated and sunk into the preformed hole, and a crawler crane and a vibration hammer are used for vibrating and sinking the steel pipe pile;

(4) dig and bore stake core and draw soil soon

Digging soil for a pile core of the steel pipe pile by adopting a rotary drilling rig, wherein the lifting height of the rotary drilling rig is adjustable, and the adjustable range is 5-10 meters;

(5) down-the-hole hammer into rock

(5.1) lower down-the-hole hammer, open the wings

After the pile core of the rotary drilling pile is excavated, the down-the-hole hammer is shifted to an operation point, the hammer head is slowly put into the pile core through a drill rod, the down-the-hole hammer reversely rotates and sinks to prevent the wings from being clamped in the pile after being opened, at the moment, the pile mainly takes liquid mud and loose soil layers as main materials, 2-3 air compressors are opened, all the air compressors are opened after the hammer head of the down-the-hole hammer contacts with an inner hoop at the bottom of the pile and generates crisp sound, the air pressure is not less than 1.4Mpa, and the reaming wings are opened in a forward rotation mode;

(5.2) blowing slag and reaming, and self-following steel pipe pile

After the wing is opened, the broken slag is discharged out of the pile through the exhaust hole of the hammer along with the rotation of the hammer, the steel pipe pile synchronously sinks along with the drilling of the hammer, when the blown slag is changed into grey rock powder from yellow mud slag and the speed is obviously reduced, the steel pipe pile is judged whether to start rock entering or not by combining pre-hole forming data in the early stage, after the steel pipe pile is determined to enter the rock, the initial elevation is recorded, and the rock breaking and slag blowing are continued until the preset rock entering depth is reached.

2. The large-diameter lock catch steel pipe pile rock entering construction process according to claim 1, characterized in that: in the step (5.1), the diameter and the ovality of the inner wall of the steel pipe pile are ensured to meet the requirement of smooth downward placement of the hammer head when the hammer head is placed.

3. The large-diameter lock catch steel pipe pile rock entering construction process according to claim 1, characterized in that: the steel pipe pile is characterized in that a protruding annular follow-up ring is arranged on the inner wall of the bottom of the steel pipe pile, an annular groove is formed in the hammer head, the annular follow-up ring is clamped in the annular groove of the hammer head, the steel pipe pile and the down-the-hole hammer are concentric, and the steel pipe pile is synchronously advanced along with the down-the-hole hammer.

4. The large-diameter lock catch steel pipe pile rock entering construction process according to claim 3, characterized in that: the wall thickness of the annular follow-up ring is larger than the diameter difference between the diameter of the hammer head in the steel pipe pile and the diameter of the inner wall of the steel pipe pile.

5. The large-diameter lock catch steel pipe pile rock entering construction process according to claim 3 or 4, characterized in that: the annular follow-up ring is made of Q345 steel through machining.

6. The large-diameter lock catch steel pipe pile rock entering construction process according to claim 1, characterized in that: in the step (5.2), in the process of advancing the down-the-hole hammer into the rock, if the advancing length of the hammer head is less than 5cm in 10 minutes, immediately stopping entering the rock, moving the down-the-hole hammer out of the pile, and checking whether equipment damage occurs or not; if the equipment is damaged, continuously putting the rock into a rock footage after repairing; if the device is not damaged, it is checked whether there are other problems.

7. The large-diameter lock catch steel pipe pile rock entering construction process according to claim 1, characterized in that: the construction process also comprises the inspection of down-the-hole hammer equipment;

the down-the-hole hammer equipment is checked after rock entering is finished, when the total station detects that the rock entering depth reaches a preset depth, the hammer head is reversed, the wing is retracted, the drill rod is lifted, and if the drill jamming phenomenon occurs, the hammer head needs to be turned again to open the wing to be knocked empty, then the wing is reversed again to be retracted and lifted, so that the wing of the hammer head is completely retracted; after the hammer head is moved out of the pile, a mechanical manipulator checks whether the hammer head cracks, wing fractures and alloy spherical teeth on a hammer head bottom plate fall off or not so as to determine whether rock breaking can be continued or not; if the hammer head cracks and the wing is broken, replacing the hammer head and the wing; if the alloy beads at the bottoms of the hammer head and the wing fall to more than one fifth, the rock-entering effect of the down-the-hole hammer is affected, the hammer head and the wing alloy beads need to be replaced, damaged old alloy beads are removed through the spark discharger, and new alloy buttons are installed.

8. The large-diameter lock catch steel pipe pile rock entering construction process according to claim 1, characterized in that: the vertical central axis of the down-the-hole hammer is in the same straight line with the vertical central axis of the pile sinking, and the vertical central axis of the pile sinking is parallel to the lock catch.

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