CN212479074U - Hard rock drilling construction system for foundation pit secant pile in height-limited area - Google Patents

Abstract

The utility model discloses a limit for height district foundation ditch secant pile hard rock drilling construction system belongs to bored concrete pile construction technical field, wherein, construction system includes the full set of pipe rotary drill and the improved generation rig that are used for being under construction in the environment on limit for height district and hard rock soil layer, and the hard rock soil layer includes upper strata soil layer and lower floor rock stratum, and full set of pipe rotary drill drive sleeve subassembly pore-forms in upper strata soil layer department, and the improved generation rig drive down-the-hole hammer pore-forms in lower floor rock stratum department; the improved drilling machine is lower than the height of the height-limiting area, is connected with a down-the-hole hammer through a drill rod assembly, the drill rod assembly is composed of a plurality of short drill rods which are connected end to end, the top end of any short drill rod is disconnected, and a new short drill rod is additionally connected to lengthen the length of the drill rod assembly; the problem of prior art adopt to dig the machine soon that the efficiency is lower and dig the drill bit soon and easily damage is solved.

Description

Hard rock drilling construction system for foundation pit secant pile in height-limited area

Technical Field

The utility model relates to a bored concrete pile construction technical field especially relates to limit for height district foundation ditch secant pile hard rock and creeps into construction system.

Background

At present, traditional construction processes such as impact hole forming and rotary drilling are generally adopted for cast-in-place pile construction operation of hard rock stratum, and a rotary excavator is generally modified in a mode of reducing the height of the rotary excavator for cast-in-place pile construction operation of a height-limited area.

Although the construction method can meet the requirement of the construction operation height of the height-limited area, the rotary drilling machine is low in power and torque, low in efficiency when the hard rock layer is drilled, and the rotary drilling bit is extremely easy to damage when facing the hard rock, so that a system and a method capable of conducting drilling construction aiming at the height-limited area and the hard rock layer are urgently needed.

SUMMERY OF THE UTILITY MODEL

In order to overcome the not enough of prior art, the utility model discloses an aim at overcome limit for height district environmental condition under the hard rock bored concrete pile creep into the difficulty, provide a new hard rock and creep into pore-forming construction technology, aim at solving among the prior art construction feasibility low, the work efficiency is low, problem with high costs.

The utility model provides a technical scheme that its technical problem adopted is:

a hard rock drilling construction system for a foundation pit secant pile in a height-limited area comprises a full-casing rotary drilling machine and an improved drilling machine, wherein the full-casing rotary drilling machine and the improved drilling machine are used for construction in the environment of the height-limited area and a hard rock soil layer, the hard rock soil layer comprises an upper soil layer and a lower rock layer, a full-casing rotary drilling machine drives a casing pipe assembly to form a hole in the upper soil layer, and the improved drilling machine drives a down-the-hole hammer to form a hole in the lower rock layer; the improved drilling machine is lower than the height of the height limiting area, is connected with a down-the-hole hammer through a drill rod assembly, the drill rod assembly is composed of a plurality of short drill rods which are connected end to end, the top end of any short drill rod is disconnected, and a new short drill rod is connected with the top end of the short drill rod assembly to lengthen the length of the drill rod assembly.

By adopting the technical scheme, a common multifunctional drilling machine is changed into an improved drilling machine with the height lower than the height of a height-limited area, the height of a full-casing rotary drilling machine is about 2-3 m, so that the full-casing rotary drilling machine and the improved drilling machine can perform hole forming work in the height-limited area, and when rock breaking work is performed on a lower rock stratum, a down-the-hole hammer is gradually placed into a hole through a drill rod assembly;

the utility model discloses a progressively lengthen the mode of drilling rod subassembly, progressively send the down-the-hole hammer to the hole bottom and carry out broken rock work, replace current machine of digging soon, solved adopt the machine of digging soon to break rock work and the inefficiency that leads to, dig the problem that the drill bit very easily damaged soon.

Preferably, one end of the short drill rod is a hexagonal female joint, the other end of the short drill rod is a hexagonal male joint, the hexagonal female joint and the hexagonal male joint are connected through a fixing bolt, and the thickness of the hole wall of the jack of the hexagonal female joint is not less than 5 mm.

By adopting the technical scheme, the hexagonal female joint of one short drill rod can be connected with the hexagonal sub-joint of the other short drill rod, so that the whole drill rod assembly is formed by head-to-tail connection, the hexagonal sub-joint of the short drill rod at the uppermost part of the drill rod assembly is connected with the power head of the improved drilling machine, and the hexagonal female joint of the short drill rod at the lowermost part of the drill rod assembly is connected with the down-the-hole hammer;

in addition, the thickness of the hole wall of the jack of the hexagonal female joint is not less than 5mm, so that the primary and secondary sleeved joint can have enough rigidity, and the drilling torque can be effectively transmitted.

Preferably, the length of the short drill rod is 2-6m, the sleeve assembly is formed by connecting a plurality of sections of sleeves end to end, and the length of each section of sleeve is 1m, 2m or 3 m.

By adopting the technical scheme, the lengths of the short drill rods and the single casing pipe are selected according to the height of the height-limited area, for example, when the height of the height-limited area is 5m, short drill rods of 2m and 3m can be adopted, and casing pipes of 1m, 2m and 3m can be adopted.

Preferably, the orifice of the hole is provided with a dustproof collecting box, the dustproof collecting box comprises a box body formed by surrounding the periphery of the hole, the box body is provided with a rubber dustproof ring abutting against a down-the-hole hammer or a drill rod assembly, and the top of the box body is communicated with a water pipe and sprays water to the interior of the box body on the upper layer.

Through adopting above-mentioned technical scheme, the down-the-hole hammer creeps into the in-process, breaks lower floor's stratum into piece to blow to the drill way through the high-pressure gas that the air compressor machine produced, when the piece blows to the drill way, receive the separation of rubber dust ring, in the air current flow direction box, the dust that carries in the upward return air current sinks to store up and stays in the box with water fog, has effectively reduced the flying dust pollution.

The utility model has the advantages that:

1. strong adaptability

The utility model discloses implement the combination process, be applicable to the special construction environment who possesses limit for height district and hard rock soil layer simultaneously, the sleeve pipe subassembly that full sleeve pipe rotary drill adopted the sleeve pipe subassembly that meets one by one to realize the work of digging soon of upper strata soil layer, and improved generation rig adopts the drilling rod subassembly that can extend to put down the hole hammer into the hole and carry out the broken rock work of lower strata;

2. the drilling efficiency of the hard rock is high

The utility model adopts the extendable drill rod component to match with the down-the-hole hammer, so that the height limitation of the height-limited area can be satisfied, and simultaneously, the problems of low drilling efficiency and easy damage of a rotary drilling bit caused by the existing rotary drilling rig are solved;

3. good quality of pore-forming

The utility model combines the combined drilling construction method of 'full casing rotary drilling machine + low clearance down-the-hole hammer', the upper soil layer adopts casing pipe assembly dado, the stability of the hole wall in the construction process is effectively improved, the sediment at the bottom of the hole is less, the quality of the formed hole is high, the quality of the pile body is good, and the control of the sedimentation and the deformation is relatively easy in the construction process;

4. no flying dust or slight flying dust in construction environment

The utility model discloses set up dustproof collecting box in drill way department, at the broken rock in-process of down-the-hole hammer, will go up the dust that carries in the return air current and pass through the water smoke deposit in the box, effectively reduced the flying dust pollution.

Drawings

The present invention will be further explained with reference to the drawings and examples.

FIG. 1 is a schematic view of the procedure for converting a crane into a modified crane according to the present invention;

FIG. 2 is a schematic structural diagram of an improved drilling machine of the present invention;

FIG. 3 is a schematic view of the extension of the sleeve assembly according to the present invention;

fig. 4 is a schematic view of the extension of a drill rod assembly according to the present invention;

fig. 5 is a schematic structural view of the female-male hexagonal joint of the present invention;

FIG. 6 is a schematic view of the construction of a dust collection box in the drilling construction system;

FIG. 7 is a schematic flow diagram of a drilling construction method;

fig. 8 is a construction diagram of the drilling construction method.

The reference numerals in the figures are explained below:

1. an improved crane;

2. an improved drilling machine; 201. a power head;

3. a bushing assembly; 301. a sleeve; 302. a screw;

4. a drill rod assembly; 401. short drill rods; 402. a drill stem is arranged in front of the drill stem; 403. subsequent drilling rods; 404. A U-shaped fixture block; 405. a hexagonal sub-joint; 406. a hexagonal female joint;

5. a down-the-hole hammer;

6. a dustproof collecting box; 601. a box body; 602. rubber dust ring.

Detailed Description

The conception, the specific structure, and the technical effects produced by the present invention will be clearly and completely described below in conjunction with the embodiments and the accompanying drawings to fully understand the objects, the features, and the effects of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all embodiments, and other embodiments obtained by those skilled in the art without inventive labor based on the embodiments of the present invention all belong to the protection scope of the present invention. In addition, all the connection/connection relations referred to in the patent do not mean that the components are directly connected, but mean that a better connection structure can be formed by adding or reducing connection auxiliary components according to specific implementation conditions. The utility model discloses each technical feature in the creation can the interactive combination under the prerequisite that does not contradict conflict each other.

The utility model provides a limit for height district foundation ditch secant pile hard rock creeps into construction system, includes improved generation crane 1, full sleeve pipe rotary drill and improved generation rig 2 that are arranged in the environment of limit for height district and hard rock soil layer to be under construction, and improved generation crane 1 is used for hanging sleeve pipe 301 to full sleeve pipe rotary drill in limit for height district, and the hard rock soil layer includes upper strata soil layer and lower floor stratum.

As shown in fig. 1, a part of the masts of the general hoist is disassembled so that the height of the hoist is lower than that of the height-limit zone to form the improved hoist 1.

As shown in fig. 2, a part of masts of the multifunctional drilling machine is disassembled to enable the height of the multifunctional drilling machine to be lower than that of the height-limiting area so as to form an improved drilling machine 2, the original mast height of the multifunctional drilling machine is 28m, the height of the improved drilling machine 2 after being modified is 8m, and the rest structures of the improved drilling machine 2 are unchanged from the original multifunctional drilling machine and mainly comprise a chassis, a mast, a follow-up frame, a power head 201, a rotating rod and a fixed frame.

As shown in fig. 3, the full casing rotary drill drives the casing assembly 3 to form a hole in the upper soil layer, the casing assembly 3 is formed by connecting a plurality of casings 301 end to end, a previous casing 301 is screwed into the hole by the full casing rotary drill, a new casing 301 is taken out and mounted to the top end of the previous casing 301 to lengthen the overall length of the casing assembly 3, and the sleeves are connected end to end by opening screw holes and penetrating through screw rods 302 in the screw holes.

The improved drilling machine 2 is connected with a down-the-hole hammer 5 through a drill rod assembly 4, the down-the-hole hammer 5 is driven to form a hole in the lower rock stratum, the height of the improved drilling machine 2 is lower than that of a height limiting area, the drill rod assembly 4 is composed of a plurality of short drill rods 401 which are connected end to end, the top end of any short drill rod 401 is disconnected, and a new short drill rod 401 is additionally connected to lengthen the length of the drill rod assembly 4.

The specific steps for lengthening the drill rod assembly 4 are as follows: selecting a short drill rod 401 as a pre-extension drill rod 402, clamping a joint at the top end of the pre-extension drill rod 402 at a hole opening by using a U-shaped fixture block 404, disconnecting the pre-extension drill rod 402 from the power head 201 of the improved drilling machine 2 or the short drill rod 401 above the pre-extension drill rod, raising the power head 201 of the improved drilling machine 2, taking a new short drill rod 401 as a subsequent drill rod 403, connecting the bottom end of the subsequent drill rod 403 with the pre-extension drill rod 402, and connecting the top end of the subsequent drill rod with the power head 201 of the improved drilling machine 2 or the short drill rod 401 above the subsequent drill.

The concrete working principle for solving the technical problem is as follows: the common multifunctional drilling machine is modified into an improved drilling machine 2 with the height lower than the height of the height-limited area, and the height of the full-casing rotary drilling machine is about 2-3 meters, so that the full-casing rotary drilling machine and the improved drilling machine 2 can perform hole forming work in the height-limited area; when the improved drilling machine 2 is used for carrying out rock breaking work on a lower rock stratum, the down-the-hole hammer 5 is gradually placed into a hole through the drill rod assembly 4, due to the limitation of a height limiting area, the height of an initial drill rod assembly 4 is certainly not enough to place the down-the-hole hammer 5 at the bottom of the hole, at the moment, the top end of any short drill rod 401 is disconnected, a new short drill rod 401 is additionally connected to lengthen the length of the drill rod assembly 4, after the down-the-hole hammer is placed to the depth of one short drill rod 401, the drill rod assembly 4 is lengthened again, and the process is repeated so that the down-the-hole hammer 5 is placed at the bottom.

The utility model discloses a progressively lengthen drilling rod subassembly 4's mode, progressively send down-the-hole hammer 5 to the hole bottom and carry out broken rock work, replace current machine of digging soon, solved adopt the machine of digging soon to break rock work and the inefficiency that leads to, dig the problem that the drill bit very easily damaged soon.

In order to realize the separable connection relationship between the short drill rod 401 and the short drill rod 401 or between the short drill rod 401 and the power head 201 of the improved drilling machine 2, the utility model discloses further define the short drill rod 401 as follows.

One end of the short drill rod 401 is a hexagonal female joint 406, the other end of the short drill rod is a hexagonal male joint 405, and the hexagonal female joint 406 is connected with the hexagonal male joint 405 through a fixing bolt.

The hexagonal female coupling 406 of one stub drill rod 401 may be connected to the hexagonal female coupling 405 of another stub drill rod 401 to achieve end-to-end extension of the entire drill rod assembly 4, the hexagonal female coupling 405 of the uppermost stub drill rod 401 of the drill rod assembly 4 being connected to the power head 201 of the modified drill rig 2 and the hexagonal female coupling 406 of the lowermost stub drill rod 401 of the drill rod assembly 4 being connected to the down-the-hole hammer 5.

Moreover, the hole wall thickness of the jack of the hexagonal female joint 406 is not less than 5 mm; the primary and secondary sleeve joints can be ensured to have enough rigidity, and drilling torque can be effectively transmitted.

The length of the short drill rod 401 is 2-6m, the sleeve assembly 3 is formed by connecting a plurality of sections of sleeves 301 end to end, and the length of each section of sleeve 301 is 1m, 2m or 3 m; the lengths of the short drill pipe 401 and the single casing 301 are selected according to the height of the height-limited zone, for example, when the height of the height-limited zone is 5m, short drill pipes 401 with the lengths of 2m and 3m can be used, and casings 301 with the lengths of 1m, 2m and 3m can be used.

When the down-the-hole hammer 5 is used for rock breaking, an air pipe connected with an air compressor is placed into the hole bottom to blow out the quercus acutissima at the hole bottom, so that the flying dust in the construction environment is excessive.

As shown in fig. 6, for solving this problem, the utility model discloses be equipped with dustproof collecting box 6 in the drill way department in hole, dustproof collecting box 6 includes and encloses the box 601 that closes the formation all around along the hole, and being equipped with of box 601 supports the rubber dust ring 602 of pressing in down-the-hole hammer 5 or drilling rod subassembly 4, and box 601 top intercommunication water pipe is to the inside water spray of box 601.

In the drilling process of the down-the-hole hammer 5, the lower rock stratum is broken into fragments, high-pressure gas generated by the air compressor is blown to the hole opening, when the fragments are blown to the hole opening, the fragments are blocked by the rubber dust ring 602, airflow flows into the box body 601, dust carried in upward-returning airflow is deposited in the box body 601 when meeting water mist, and flying dust pollution is effectively reduced.

In fig. 6, a tank 601 is divided into an upper tank and a lower tank, and a filter screen capable of filtering water is used at the joint of the upper tank and the lower tank to drain excess water in the upper tank into the lower tank.

Furthermore, the utility model discloses still provide a construction method who corresponds with above-mentioned construction system as follows.

A construction method for drilling a hard rock of a secant pile of a foundation pit in a height-limited area is shown in figures 7 and 8 and comprises the following steps:

s1, preparing an improved crane 1, a full casing rotary drilling machine and an improved drilling machine 2;

the improved crane 1 and the improved drilling machine 2 are modified in the following modes: part of the mast of the crane is dismantled to make the height of the crane lower than the height of the height-limiting zone to form the improved crane 1, and part of the mast of the multifunctional drilling machine is dismantled to make the height of the drilling machine lower than the height of the height-limiting zone to form the improved drilling machine 2.

S2, moving the full-casing rotary drilling machine to a preset position, hoisting the first casing 301 with the high-strength alloy cutter head to the full-casing rotary drilling machine by using the improved crane 1, and driving the first casing 301 to form a hole in an upper soil layer by the full-casing rotary drilling machine;

the step of S2 is specifically: hoisting the first section of casing 301 by using an improved crane 1, and installing the first section of casing 301; first section sleeve pipe 301 has the high strength alloy tool bit, and first section sleeve pipe 301's construction effect is the main factor that influences the straightness that hangs down of pile foundation, consequently need guarantee that it is perpendicular as far as possible, pushes down the in-process from two axis directions of X and Y, utilizes the survey hammer cooperation theodolite (total powerstation) to detect sleeve pipe 301 straightness that hangs down, if the skew phenomenon appears, the landing leg hydro-cylinder of adjustable full-slewing drilling machine guarantees that sleeve pipe 301 is perpendicular (must detect with the theodolite after the adjustment).

S3, after the full casing rotary drilling machine drives the previous casing 301 to be screwed into the hole, the next casing 301 is hung to the full casing rotary drilling machine by using the improved crane 1, and the bottom of the next casing 301 is fixedly connected with the top of the previous casing 301.

In step S3, each casing 301 has a length of 1m, 2m, or 3 m.

When the full-casing rotary drilling machine drills to a position just before drilling to a lower rock stratum, the casing 301 with a proper length is reasonably installed, and the situation that the casing assembly 3 is not long enough or is exposed too much to cause inconvenience in subsequent work when the casing 301 reaches the lower rock stratum is avoided. For example, after a full casing rotary drill rig drills a casing assembly 3 down to a distance of 10m from the formation, 3 casings 301 of 3m and 1 casing 301 of 1m may be selected for subsequent drilling operations.

In the steps of S2 and S3, soil sampling is carried out in a mode of rotating and punching and grabbing soil while drilling by the full-casing rotary drilling machine, and the casing 301 needs to advance to drill at least more than 0.5 m.

S4, repeating step S3 until the sleeve assembly 3 is completely drilled at the upper soil layer.

Up to this point, the upper soil layer is completely formed by the full casing rotary drilling machine, the casing pipe assembly 3 is installed on the hole wall, and then rock breaking and hole forming are carried out on the lower rock layer.

S5, moving the modified drill 2 to a preset position, and mounting the down-the-hole hammer 5 to the modified drill 2 using the drill rod assembly 4.

In step S5, the drill rod assembly 4 is composed of a plurality of short drill rods 401 that are connected end to end, the length of each short drill rod 401 is 2-6m, one end of each short drill rod 401 is a hexagonal female joint 406, the other end of each short drill rod 401 is a hexagonal male joint 405, the hexagonal female joint 406 and the hexagonal male joint 405 are connected through a fixing bolt, and the hole wall thickness of the insertion hole of the hexagonal female joint 406 is not less than 5 mm.

S6, the down-the-hole hammer 5 is driven into the bottom of the hole, the lower rock stratum is broken and drilled to the designed depth, when the length of the drill rod assembly 4 is insufficient, the top end of any short drill rod 401 is disconnected, and a new short drill rod 401 is additionally connected to lengthen the length of the drill rod assembly 4;

in step S6, the specific steps for lengthening the drill rod assembly 4 are as follows: selecting a short drill rod 401 as a pre-extension drill rod 402, clamping a joint at the top end of the pre-extension drill rod 402 at a hole opening by using a U-shaped fixture block 404, disconnecting the pre-extension drill rod 402 from the power head 201 of the improved drilling machine 2 or the short drill rod 401 above the pre-extension drill rod, raising the power head 201 of the improved drilling machine 2, taking a new short drill rod 401 as a subsequent drill rod 403, connecting the bottom end of the subsequent drill rod 403 with the pre-extension drill rod 402, and connecting the top end of the subsequent drill rod with the power head 201 of the improved drilling machine 2 or the short drill rod 401 above the subsequent drill.

After the lower rock stratum is drilled to the designed depth, the power head 201 of the improved drilling machine 2 is lifted to the top of the height-limiting area, then the top end of the short drill rod 401 close to the hole opening is clamped by the U-shaped fixture block 404, the short drill rod 401 between the short drill rod 401 and the power head 201 is detached, the lower end of the power head 201 is connected with the top end of the short drill rod 401 at the hole opening, then the power head 201 of the improved drilling machine 2 is lifted to the top of the height-limiting area, and the down-the-hole hammer 5 is moved out of the hole by repeated operation.

After upper soil layer and lower floor's stratum have all become the pore-forming, the limit for height district hard rock creeps into the construction process and accomplishes, later installs processes such as steel reinforcement cage, fills the pipe, includes as follows:

s7, placing a reinforcement cage and a perfusion catheter

1. According to the actual situation on site, a construction method of lifting the steel reinforcement cage into the hole in sections is adopted, and the connection of the steel reinforcement cages at the hole openings is realized through sleeve connection;

2. after the connection of the steel reinforcement cage is finished, the steel reinforcement cage is aligned to a hole position during hoisting, and the steel reinforcement cage is vertically and stably hung and slowly lowered in place;

3. selecting a pipe with the diameter of 300mm for the concrete pouring pipe, checking each section of pipe before placing the pipe, and performing a sealing hydraulic test when the pipe is used for the first time; sealing rings are added at the connecting parts of the guide pipes and butter is smeared, so that reliable sealing is ensured, and the bottom of each guide pipe is 300-500 mm away from the bottom of each hole; when the catheter is inserted, the length of the catheter is adjusted and matched.

S8, pouring concrete and pulling out the sleeve 301

1. After the placement of the reinforcement cage and the pouring guide pipe is finished, measuring the sediment at the bottom of the hole, and pouring underwater concrete if the sediment meets the requirements; if the thickness of the sediment at the bottom of the hole exceeds the standard, gas lift reverse circulation is adopted for secondary hole cleaning;

2. c35 underwater commercial concrete is adopted as the pile body concrete, the slump is 180-220 mm, the project adopts a hopper pouring method for pouring the concrete, the initial pouring is to ensure that the concrete can block the bottom of the hole, and 2-3 m3 concrete is poured at one time;

3. the sleeve 301 is pulled out by adopting a vibration clamp; in the concrete pouring process, the sleeve 301 and the guide pipe are pulled up frequently according to the pouring height, so that the sleeve 301 and the guide pipe are prevented from being solidified in the concrete, the sleeve 301 and the guide pipe are strictly controlled to be prevented from being pulled up too fast to expose the concrete surface, the pile breaking risk is caused, the bottom openings of the sleeve 301 and the guide pipe are kept 2-4 m lower than the concrete surface, and the maximum length of the bottom openings cannot be larger than 6 m;

4. in the concrete pouring process, the hopper and the guide pipe are lifted up and down from time to time so that the concrete in the pipe can be smoothly put into the hole until the height of the pile top is over-poured by 0.8-1.0 m when the concrete is poured to the designed elevation position.

While the preferred embodiments of the present invention have been described, the present invention is not limited to the above embodiments, and those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention, and such equivalent modifications or substitutions are intended to be included within the scope of the present invention as defined by the appended claims.

Claims (4)

1. The hard rock drilling construction system for the foundation pit secant pile in the height-limited area is characterized by comprising a full-casing rotary drilling machine and an improved drilling machine, wherein the full-casing rotary drilling machine and the improved drilling machine are used for construction in the environment of the height-limited area and a hard rock soil layer, the hard rock soil layer comprises an upper soil layer and a lower rock layer, the full-casing rotary drilling machine drives a casing pipe assembly to form a hole in the upper soil layer, and the improved drilling machine drives a down-the-hole hammer to form a hole in the lower rock layer;

the improved drilling machine is lower than the height of the height limiting area, is connected with a down-the-hole hammer through a drill rod assembly, the drill rod assembly is composed of a plurality of short drill rods which are connected end to end, the top end of any short drill rod is disconnected, and a new short drill rod is connected with the top end of the short drill rod assembly to lengthen the length of the drill rod assembly.

2. The hard rock drilling construction system for the secant pile of the foundation pit in the height-limited area according to claim 1, wherein one end of the short drill rod is a hexagonal female joint, the other end of the short drill rod is a hexagonal male joint, the hexagonal female joint and the hexagonal male joint are connected through a fixing bolt, and the thickness of the hole wall of the jack of the hexagonal female joint is not less than 5 mm.

3. The hard rock drilling construction system for the ground pit occlusive pile in the height-limited area as claimed in claim 1, wherein the length of the short drill rod is 2-6m, the sleeve assembly is composed of a plurality of sleeves which are connected end to end, and the length of each sleeve is 1m, 2m or 3 m.

4. The system for hard rock drilling construction of the foundation pit snap-in pile of the height-limiting area as claimed in claim 1, wherein a dustproof collecting box is arranged at the opening of the hole, the dustproof collecting box comprises a box body formed by enclosing the periphery of the hole, a rubber dustproof ring pressed against a down-the-hole hammer or a drill rod assembly is arranged on the box body, and the top of the box body is communicated with a water pipe and sprays water to the interior of the upper-layer box body.

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