Synchronous hole-forming installation construction method for deep foundation pit dewatering well

Abstract

The invention relates to a deep foundation pit dewatering well synchronous hole-forming installation construction method, which is characterized in that a dewatering well pipe is arranged in a hollow spiral drill rod, and a conical split spiral drill bit is arranged at the bottom end of the spiral drill rod, so that the drill bit can be closed during drilling through a spring stretching piece; opening of a drill bit and synchronous lowering of a well pipe after drilling and forming can be achieved through downward pressing of the telescopic rod piece, the processes of well digging, drilling and well pipe lowering in the traditional foundation pit dewatering process are fused, the construction time is saved, the structure is reasonable, and construction is convenient; the roller is arranged between the drill rod of the spiral drill and the well casing of the dewatering well, so that the well casing is centered in a drill hole, and the mounting stability of the dewatering well casing is improved; when the drill rod of the spiral drill is separated from the well casing of the dewatering well, the drill bit of the spiral drill is expanded by utilizing the downward pressing of the telescopic rod piece, the self weight of the well casing and the antifriction and limiting effects of the hoop rollers, and the synchronous and rapid installation of the well casing of the dewatering well after hole forming is further realized.

Description

Technical Field

[0001] The invention belongs to the field of foundation pit dewatering construction, and in particular relates to a synchronous hole-forming and installation construction method for a deep foundation pit dewatering well. Background Art

[0002] Foundation pit dewatering refers to the dewatering work done when the groundwater level is higher than the bottom of the excavation during foundation pit excavation, and the groundwater will continue to seep into the pit to ensure that the foundation pit can be constructed under dry conditions, to prevent slope instability, foundation sand flow, pit bottom uplift, pit bottom pipe bursts, and a decrease in foundation bearing capacity. For pipe well point dewatering, the precise lowering and installation of the dewatering well is often the key to controlling the foundation pit dewatering effect. Traditional dewatering well pipe installation must often be carried out after drilling, and the construction period is limited; affected by factors such as borehole size, wall protection mud, and mechanical vibration, the accuracy of pipe lowering cannot be effectively guaranteed; moreover, after the well pipe is lowered into place, the bottom of the pipe and the surrounding pores must be backfilled in time to ensure the firmness and stability of the dewatering well pipe.

[0003] Therefore, in order to optimize the construction period of foundation pit dewatering, relevant research was carried out on the current problems, and the commonly used methods were compared. After analysis and combination with actual conditions, the traditional spiral hole drilling installation construction method was transformed to find a dewatering well pipe installation construction method that is quick and convenient to install, accurately positioned, and has a stable structure. Ensuring the accuracy and stability of the dewatering well installation is an issue that needs to be solved urgently. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a method for synchronously drilling and installing a deep foundation pit dewatering well.

[0005] The method for synchronously drilling and installing a deep foundation pit dewatering well comprises the following steps:

[0006] Step 1, construction preparation stage: install the backfill pipe on the outer wall of the precipitation well pipe, place the precipitation well pipe inside the auger drill rod, and install the auger drill rod on the drilling rig;

[0007] Step 2, drilling construction stage: start the spiral drive device, the spiral drill rod cuts the soil to form a borehole, until the well pipe of the drainage well is synchronously moved down to the designed depth;

[0008] Step 3, well pipe lowering stage: the retractable rod in the spiral drive device presses down against the well pipe of the dewatering well to lift the auger drill rod;

[0009] Step 4: Backfill and seal stage: fill the bottom of the well pipe with fine-grained sand and gravel, and inject grout around the well pipe.

[0010] Preferably, in step one, the auger drill rod is a hollow structure, with auger blades spirally arranged around the outer wall, rollers symmetrically arranged on the inner wall, an internal thread arranged on the upper end of the auger drill rod, and an auger drill bit arranged on the lower end; a backfill pipe is fixed to the outer wall of the dewatering well pipe by a clamp, the backfill pipe is connected to a hose, and a hoop roller is arranged at the bottom end of the dewatering well pipe; when placing the dewatering well pipe inside the auger drill rod, it also includes adjusting the direction of the dewatering well pipe to avoid collision between the roller and the backfill pipe, ensuring that the well pipe body is in contact with the roller, and the hoop roller is in contact with the inner wall of the auger drill bit.

[0011] Preferably, in step one, the auger drill rod is connected to the spiral drive device of the drilling rig through a connecting mechanism, and the connecting mechanism is screwed and fixed to the spiral drive device and the auger drill rod through external threads at both ends, respectively, for transmitting torque to achieve drilling; the spiral drive device is fixed to the drilling rig through a mechanical arm, and an internal thread is provided at the lower end of the spiral drive device.

[0012] Preferably, in step 2, the auger drill bit is a conical petal-shaped symmetrical structure, hinged to the bottom end of the auger drill rod through a rotating shaft, and a spring tensioning member is provided between the auger drill bit and the inner wall of the auger drill rod.

[0013] Preferably, in step 4, the backfill pipe wall is evenly provided with grouting holes and is wrapped with geotextile all around.

[0014] Preferably, a hydraulic retractable rod is vertically provided inside the spiral drive device above the dewatering well pipe; in step three, after the hole is formed, the retractable rod in the spiral drive device is started to descend until it contacts the dewatering well pipe, and the auger drill rod is simultaneously lifted, and the auger drill bit is propped open by the reverse pressure of the dewatering well pipe through the retractable rod, so that the dewatering well pipe and the auger drill rod are gradually separated.

[0015] The beneficial effects of the present invention are:

[0016] 1) The present invention embeds the well pipe of the dewatering well into the hollow auger drill rod, and arranges a conical lobed auger drill bit at the bottom end of the auger drill rod. The drill bit can be closed during drilling by a spring tensioning member, and the drill bit can be opened and the well pipe can be lowered synchronously after the hole is formed by pressing down the retractable rod. This integrates the processes of well drilling and well pipe lowering in the traditional process of foundation pit dewatering, saves construction time, has a reasonable structure, and is convenient for construction.

[0017] 2) The present invention arranges rollers between the auger drill rod and the drainage well pipe, thereby ensuring that the well pipe is centered in the borehole and improving the installation stability of the drainage well pipe; when separating the auger drill rod and the drainage well pipe, the downward pressure of the telescopic rod, the deadweight of the well pipe and the friction reduction and limiting effect of the hoop roller are utilized to facilitate the opening of the auger drill bit, thereby further realizing the synchronous and rapid installation of the drainage well pipe after the hole is formed.

[0018] 3) The present invention has a backfill pipe preset on the outer wall of the well pipe of the dewatering well, which can timely backfill sand and gravel into the bottom of the well pipe when the spiral drill rod is pulled up, effectively preventing the well pipe from loosening and deviating; at the same time, grouting is injected around the well pipe body to achieve rapid sealing of the gap between the well pipe and the drill hole, effectively ensuring the dewatering effect of the well pipe. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Installation plan for simultaneous drilling of dewatering wells;

[0020] Figure 2 It is the overall schematic diagram of the auger drill rod;

[0021] Figure 3 This is a schematic diagram of the backfill pipe structure;

[0022] Figure 4 This is a schematic diagram of the connection between the auger drill rod and the drilling rig;

[0023] Figure 5 After drilling Figure 1 AA section view in;

[0024] Figure 6 After drilling Figure 1 BB section diagram in;

[0025] Figure 7 Well pipe lowering stage Figure 1 AA section view in;

[0026] Figure 8 Backfill sealing stage Figure 1 BB cross-section diagram in.

[0027] Explanation of the reference numerals in the accompanying drawings: 1. Drill hole; 2. Auger drill rod; 3. Auger blade; 4. Auger drill bit; 5. Rotating shaft; 6. Spring tension member; 7. Well pipe of dewatering well; 8. Roller; 9. Hoop roller; 10. Backfill pipe; 11. Fastener; 12. Sand and gravel; 13. Connecting mechanism; 14. Screw drive device; 15. Drilling rig; 16. Retractable rod; 17. Grouting hole; 18. Geotextile; 19. Hose; 20. Backfill grouting device; 21. Robotic arm. DETAILED DESCRIPTION

[0028] The present invention is further described below in conjunction with embodiments. The description of the following embodiments is only used to help understand the present invention. It should be noted that for ordinary persons in the art, without departing from the principle of the present invention, the present invention can also be modified in some ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0029] Embodiment 1

[0030] As an example, Figures 1 to 8 As shown, this deep foundation pit dewatering well synchronous drilling and installation construction method includes the following steps:

[0031] Step 1, construction preparation stage: first, install the backfill pipe 10 on the outer wall of the drainage well pipe 7, and install the sleeve roller 9 at the bottom of the well pipe; then, place the drainage well pipe 7 inside the auger drill rod 2, connect the backfill pipe 10 and the hose 19, and connect the auger drill rod 2 to the spiral drive device 14 of the drilling rig 15 through the connecting mechanism 13.

[0032] Step 2, drilling construction stage: Under the premise of ensuring that the auger drill rod 2 is vertical, start the spiral drive device 14, and cut the soil to form a borehole 1 under the action of the auger blades 3 and the auger drill bit 4, until the drainage well pipe 7 moves down to the designed depth synchronously with the auger drill rod 2.

[0033] Step 3, well pipe lowering stage: after the borehole 1 is formed, the retractable rod 16 in the spiral drive device 14 is started to lower it until it contacts the well pipe 7 of the dewatering well, and the auger drill pipe 2 is slowly lifted simultaneously, and the auger drill bit 4 is propped open by the retractable rod 16 to gradually separate the well pipe 7 of the dewatering well from the auger drill pipe 2.

[0034] Embodiment 2

[0035] As another embodiment, this embodiment 2 proposes, based on the embodiment 1, a more specific method for synchronous drilling and installation of deep foundation pit dewatering wells:

[0036] In step one, if Figures 1 to 4As shown, before construction, two symmetrical backfill pipes 10 are first fixed to the outer wall of the concrete or steel structure of the precipitation well pipe 7 by using a clamp (11), and the side wall of the backfill pipe 10 is evenly provided with grouting holes 17 and wrapped with a layer of geotextile 18 to prevent the grouting holes 17 from being blocked. The backfill pipe (10) extends to the bottom of the well pipe, and a ring of fixed hoop rollers 9 are installed around the bottom of the precipitation well pipe 7. The number of hoop rollers 9 is consistent with the number of petals of the spiral drill bit (4). Subsequently, the precipitation well pipe 7 is placed inside the spiral drill rod 2 along the rollers 8, and the direction of the precipitation well pipe 7 is adjusted so that the backfill pipe 10 is placed between two adjacent rows of rollers 8, and the two ends of the spring tension member (6) are respectively connected to the spiral drill rod (2) and the inner wall of the spiral drill bit (4). After the auger drill rod 2 is assembled, the backfill pipe 10 is connected to the hose 19, and the reserved length of the hose 19 is ensured to be sufficient for backfilling during the subsequent separation of the drainage well pipe 7 and the auger drill rod 2; the auger drill rod (2) is connected to the spiral drive device (14) of the drilling rig 15 through the connecting mechanism (13), and the auger drill rod (2) with the drainage well pipe 7 built in is installed on the drilling rig 15. After the site is cleaned and leveled, and the surveying and positioning are carried out, drilling is started at the designed position of the drainage well.

[0037] The connecting mechanism 13 is screwed and fixed to the spiral driving device 14 and the spiral drill rod 2 through external threads at both ends, so as to transmit torque to realize drilling; the spiral driving device 14 is fixed to the drilling rig 15 through a mechanical arm 21, and is provided with an internal thread at the lower end and a hydraulic retractable rod 16 inside.

[0038] In step 2, if Figure 5 and Figure 6 As shown, during the drilling construction, under the premise of ensuring that the auger drill rod 2 is vertical, the spiral driving device 14 is started to drive the auger drill rod 2 to rotate, and the soil is cut to form a borehole 1 under the action of the auger blades 3 and the auger drill bit 4. During this period, under the tension of the spring tension member 6, the conical petal-shaped auger drill bit 4 always remains in a closed state. During the drilling process, the drainage well pipe 7 moves down synchronously with the auger drill rod 2 to the designed depth.

[0039] In step three, if Figure 7As shown, after the borehole 1 is formed, the telescopic rod 16 in the spiral drive device 14 is started to gradually descend until it contacts the drainage well pipe 7. At this time, the drilling rig 15 is operated to synchronously and slowly lift the spiral drill rod 2. Under the counterpressure of the telescopic rod 16, the drainage well pipe 7 opens the spiral drill bit 4 into a symmetrical four-petal structure; then the spiral drill rod 2 is continued to be lifted, so that the drainage well pipe 7 and the spiral drill rod 2 are gradually separated. By lifting the spiral drill rod 2 and counterpressing the drainage well pipe 7, the in-situ synchronous installation of the drainage well pipe 7 after the hole is formed is realized. In the above process, the deadweight of the well pipe, the friction reduction limit of the roller 8, and the friction reduction of the sleeve roller 9 all play a certain role in assisting. In order to prevent the spiral drill bit from scratching the outer wall structure of the drainage well pipe during the process of lifting the spiral drill rod, certain protective measures can be taken on the well pipe or the drill bit contact surface if necessary.

[0040] It should be noted that the parts in this embodiment that are the same or similar to those in the first embodiment can be referenced to each other and will not be described in detail in this application.

[0041] Embodiment 3

[0042] As another embodiment, this embodiment 3 proposes a more specific method for synchronous drilling and installation of deep foundation pit dewatering wells based on the first and second embodiments:

[0043] Specifically, it also includes step 4, backfilling and sealing stage:

[0044] The backfill pipe 10 is evenly distributed with grouting holes 17 on its wall and is surrounded by a geotextile 18 .

[0045] As the auger drill rod 2 is lifted, the backfill grouting device 20 is used to fill the bottom of the precipitation well pipe 7 with fine-grained sand and gravel 12, effectively preventing the precipitation well pipe 7 from loosening and shifting; then grouting is injected around the precipitation well pipe 7 to achieve rapid sealing of the gap between the precipitation well pipe 7 and the borehole 1, until the auger drill rod 2 is completely pulled out, completing the synchronous installation of the precipitation well pipe 7.

[0046] like Figure 8As shown, when the auger drill rod 2 starts to rise and separates from the well pipe 7 of the dewatering well and exposes the bottom of the pipe, the backfill grouting device 20 is promptly used to fill the bottom of the well pipe 7 of the dewatering well through the hose 19 and the backfill pipe 10 with fine-grained sand and gravel 12, and the filling length is not less than 1m, which not only ensures the stability of the bottom of the well pipe, but also ensures the dewatering effect as a drainage channel; as the auger drill rod 2 continues to rise, the backfill grouting device 20 is used to fill the surroundings of the well pipe 7 of the dewatering well through the hose 19 and the backfill pipe 10, so as to ensure that the gap between the well pipe 7 of the dewatering well and the borehole 1 is dense, until the auger drill rod 2 is completely pulled out, the clay is sealed, and the synchronous installation of the well pipe 7 of the dewatering well is completed. Among them, the specific range of different backfill sections such as sand and gravel, grouting, etc. can be comprehensively determined according to the on-site geological conditions and hydrological conditions.

[0047] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

Claims

1. A method for synchronous drilling and installation of deep foundation pit dewatering wells, characterized in that: The following steps are involved: Step 1, construction preparation stage: install the backfill pipe on the outer wall of the precipitation well pipe, place the precipitation well pipe inside the auger drill rod, and install the auger drill rod on the drilling rig; Step 2, drilling construction stage: start the spiral drive device, the spiral drill rod cuts the soil to form a borehole, until the well pipe of the drainage well is synchronously moved down to the designed depth; Step 3, well pipe lowering stage: the retractable rod in the spiral drive device presses down against the well pipe of the dewatering well to lift the auger drill rod; Step 4: Backfill and seal stage: fill the bottom of the well pipe with fine-grained sand and gravel, and inject grout around the well pipe.

2. The method for synchronously drilling and installing a deep foundation pit dewatering well according to claim 1 is characterized in that: In step one, the auger drill rod is a hollow structure, with auger blades spirally arranged around the outer wall, rollers symmetrically arranged on the inner wall, an internal thread arranged on the upper end of the auger drill rod, and an auger drill bit arranged on the lower end; a backfill pipe is fixed to the outer wall of the dewatering well pipe by a clamp, the backfill pipe is connected to a hose, and a hoop roller is arranged at the bottom end of the dewatering well pipe; when placing the dewatering well pipe inside the auger drill rod, it also includes adjusting the direction of the dewatering well pipe to avoid collision between the roller and the backfill pipe, ensuring that the well pipe body is in contact with the roller, and the hoop roller is in contact with the inner wall of the auger drill bit.

3. The method for synchronously drilling and installing a deep foundation pit dewatering well according to claim 1 is characterized in that: In step one, the auger drill rod is connected to the spiral drive device of the drilling rig through a connecting mechanism, and the connecting mechanism is screwed and fixed to the spiral drive device and the auger drill rod through external threads at both ends, so as to transmit torque to realize drilling; the spiral drive device is fixed to the drilling rig through a mechanical arm, and an internal thread is provided at the lower end of the spiral drive device.

4. The method for synchronously drilling and installing a deep foundation pit dewatering well according to claim 2 is characterized in that: In step 2, the auger drill bit is a conical petal-shaped symmetrical structure, which is hinged to the bottom end of the auger drill rod through a rotating shaft, and a spring tensioning member is provided between the auger drill bit and the inner wall of the auger drill rod.

5. The method for synchronously drilling and installing a deep foundation pit dewatering well according to claim 1 is characterized in that: In step 4, grouting holes are evenly distributed on the wall of the backfill pipe, and the pipe is wrapped with geotextile all around.

6. The method for synchronously drilling and installing a deep foundation pit dewatering well according to claim 4 is characterized in that: A hydraulic retractable rod is vertically provided inside the spiral drive device above the well pipe of the dewatering well. In step three, after the hole is formed, the retractable rod in the spiral drive device is started to descend until it contacts the well pipe of the dewatering well, and the auger drill rod is lifted simultaneously. The auger drill bit is propped open by the reverse pressure of the retractable rod against the well pipe of the dewatering well, so that the well pipe of the dewatering well and the auger drill rod are gradually separated.

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