Drilling combination anti-collapse structure in karst development area

Abstract

This application discloses a combined anti-collapse structure for boreholes in karst development areas, including a bottom casing and multiple intermediate casings. The bottom of the intermediate casings is connected to the bottom casing, and the multiple intermediate casings are connected end-to-end. The bottom end of the bottom casing is provided with cutting teeth. The structure also includes: reinforcing protrusions, spaced circumferentially along the inner side of the bottom casing or intermediate casings; and a tapering zone, with a tapering zone at the bottom of the reinforcing protrusions within the bottom casing. The bottom casing and multiple intermediate casings constitute the borehole wall, preventing borehole collapse during drilling. The casing can be rotated and pressed down by an external force applied by a torque power head configured on the top working platform, and the cutting teeth cut into the rock mass synchronously with the drill bit. The reinforcing protrusions effectively enhance the strength and rigidity of the bottom and intermediate casings, and effectively reduce deformation and warping of the bottom and intermediate casings by dispersing stress and absorbing energy.

Description

Technical Field

[0001] This application relates to the field of borehole collapse prevention technology, and in particular to borehole combined collapse prevention structures in karst development areas. Background Technology

[0002] The GZSG-3 section of the new Zhuhai-Zhaoqing High-Speed ​​Railway Gaoming-Zhaoqing East section's pre-station engineering project spans from DK25+565 to DK41+207.817, with a total length of 15.643km. The Xijiang Grand Bridge is located between Yong'an Town and Shapu Town in Zhaoqing City, Guangdong Province. Approximately 3.5km downstream of the existing Xijiang Grand Bridge on the Jiangzhao Expressway, it crosses the main channel of the Xijiang River as a three-tower cable-stayed bridge with spans of (70+148+435+435+148+70)m. It is the largest span among the three-tower steel box girder cable-stayed bridges along the high-speed railway and is a key and challenging project controlling the entire line.

[0003] Due to the large water depth at the main tower foundation of the Xijiang Grand Bridge, reaching a maximum depth of approximately 30 meters, and the complex geological conditions in the main pier construction area, drilling and on-site investigations revealed that karst is mainly developed in the section from DK29+250 to DK32+300, with a total karst rate of 21.78%. The cave height ranges from 0.30 to 18.8 meters, with some caves being unfilled to fully filled, and some caves exhibiting a beaded pattern. The linear karst rate is 9.44%, with the cave top elevation ranging from -57.85 to -5.79 meters and the strata depth from 13.0 to 60.0 meters. The strong karst development has a significant impact on the project quality and construction safety. Encountering large caves during construction may pose a risk of large-scale borehole collapse.

[0004] In existing technologies, the casing follow-up method is used to avoid hole collapse. The casing is rotated and pressed down by the full casing drilling rig while drilling. However, during rotary drilling, the casing is subjected to the pressure of the outer ring rock mass, the pressure of the inner ring cleaning mud, and strong water pressure, which makes the casing prone to deformation.

[0005] Therefore, it is necessary to propose a combined anti-collapse structure for boreholes in karst development areas and improve the strength of the anti-collapse casing, which has become an important technical problem that urgently needs to be solved. Utility Model Content

[0006] This application provides a combined anti-collapse structure for boreholes in karst development areas, aiming to solve the problem in the prior art where the casing is subjected to pressure from the outer ring rock mass, pressure from the inner ring cleaning mud, and strong water pressure, which makes the casing prone to deformation.

[0007] To achieve the above objectives, this application proposes a combined anti-collapse structure for boreholes in karst development areas, including a bottom casing and multiple intermediate casings. The bottom intermediate casings are connected to the bottom casing, and the multiple intermediate casings are connected end to end. The bottom end of the bottom casing is provided with cutting teeth. The structure also includes: reinforcing protrusions, which are spaced circumferentially on the inner side of the bottom casing or intermediate casings; and a tapering zone, which is provided at the bottom of the reinforcing protrusions inside the bottom casing.

[0008] In some embodiments, it further includes: a male connector, with a male connector provided at the top of the bottom sleeve and one end of the middle sleeve; and a female connector, with a female connector provided at the other end of the middle sleeve.

[0009] In some embodiments, the device further includes: a first groove area, wherein a plurality of first groove areas are provided at circumferential intervals on the outer peripheral surface of the male connector; and a connecting hole, wherein connecting holes are provided on both the first groove areas and the female connector.

[0010] In some embodiments, the reinforcement protrusion further includes: a connecting protrusion disposed at the top end of the reinforcement protrusion; and a connecting groove disposed at the bottom end of the reinforcement protrusion to accommodate the connecting protrusion.

[0011] In some embodiments, the device further includes a guide portion, wherein the guide portion is disposed on the top of the connecting protrusion.

[0012] In some embodiments, it further includes: a second grooving area, wherein a plurality of second grooving areas are provided circumferentially at the bottom of the bottom sleeve, and cutting teeth are provided in the second grooving areas.

[0013] This application proposes a combined anti-collapse structure for boreholes in karst development areas, including a bottom casing and multiple intermediate casings. The bottom intermediate casings are connected to the bottom casing, and the multiple intermediate casings are connected end-to-end. The bottom end of the bottom casing is equipped with cutting teeth. The structure also includes: reinforcing protrusions spaced circumferentially on the inner side of the bottom or intermediate casings; and a tapering zone at the bottom of the reinforcing protrusions within the bottom casing. The bottom casing and multiple intermediate casings constitute the borehole wall, preventing borehole collapse during drilling. Furthermore, because the bottom casing and multiple intermediate casings are rotated downwards, they generate almost no vibration, making it less likely to induce large-scale borehole collapse accidents in karst development areas. The casing can be rotated downwards by applying external force via a torque power head mounted on the top working platform, with the cutting teeth cutting into the rock mass synchronously with the drill bit. The reinforcing protrusions effectively enhance the strength and rigidity of the bottom and intermediate casings, and can effectively reduce deformation and warping of the bottom and intermediate casings by dispersing stress and absorbing energy. Furthermore, during rotary drilling, the reinforcing protrusion can effectively compress the internal rock mass, disrupting its integrity and facilitating subsequent drill bit advancement. The tapering zone design also helps the reinforcing protrusion penetrate the rock mass. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein: Figure 1This is a three-dimensional structural diagram of a borehole-combined anti-collapse structure in a karst development area according to one embodiment of this application; Figure 2 for Figure 1 Enlarged view of part A in the middle; Figure 3 This is a cross-sectional view of a borehole-combined anti-collapse structure in a karst development area according to one embodiment of this application; Figure 4 for Figure 3 Enlarged view of part B in the middle; Figure 5 This is a three-dimensional structural diagram of the intermediate protective sleeve in one embodiment of this application.

[0015] In the figure: bottom sleeve 1, middle sleeve 2, first groove area 3, cutting tooth 4, connecting protrusion 5, guide part 6, connecting hole 7, reinforcing protrusion 8, tapering area 9, male connecting end 10, female connecting end 11. Detailed Implementation

[0016] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0017] See Figure 1 , Figure 3 , Figure 4 and Figure 5 As shown, this application proposes a combined anti-collapse structure for boreholes in karst development areas, including a bottom casing 1 and multiple intermediate casings 2. The bottom intermediate casings 2 are connected to the bottom casing 1, and the multiple intermediate casings 2 are connected end to end. The bottom end of the bottom casing 1 is provided with cutting teeth 4. It also includes: reinforcing protrusions 8, which are provided at intervals along the circumference on the inner side of the bottom casing 1 or the intermediate casings 2; and a tapering zone 9, which is provided at the bottom of the reinforcing protrusions 8 inside the bottom casing 1.

[0018] The bottom casing 1 and multiple intermediate casings 2 constitute the casing for preventing borehole collapse. The number of intermediate casings 2 can be selected according to the depth of the borehole to adapt to the borehole depth. A working platform is set at the top of the casing, and a torque power head is configured on the working platform. The torque power head is preferably a full casing drilling rig. Since full casing drilling rigs are mature existing technology and are not the inventive point of this application, the specific structure of the full casing drilling rig is not limited here. The bottom casing 1 and multiple intermediate casings 2 rotate and press down under the drive of the full casing drilling rig to form the borehole wall, preventing borehole collapse during drilling. Furthermore, since the bottom casing 1 and multiple intermediate casings 2 rotate and press down, they hardly generate vibration, and are less likely to induce large-scale borehole collapse accidents in karst development areas.

[0019] The design of the cutting teeth 4 reduces sinking resistance, protects the bottom casing 1, and enhances the stability of the bottom casing 1 and multiple intermediate casings 2 during rotational sinking. The reinforcing protrusion 8 is the core structure of the borehole assembly anti-collapse structure in karst development areas. The reinforcing protrusion 8 is integrally formed with the bottom casing 1 or intermediate casing 2, effectively enhancing the strength and rigidity of the bottom casing 1 and intermediate casing 2. Furthermore, it effectively reduces deformation and warping of the bottom casing 1 and intermediate casing 2 by dispersing stress and absorbing energy. During rotary drilling, the reinforcing protrusion 8 can also effectively compress the internal rock mass, disrupting its integrity and facilitating subsequent drill bit advance. The tapering zone 9 facilitates the insertion of the reinforcing protrusion 8 into the rock mass.

[0020] In this embodiment, the surface of the reinforcing protrusion 8 away from the bottom protective cylinder 1 and the plurality of intermediate protective cylinders 2 is an arc-shaped surface. The arc-shaped surface smoothly transitions with the inner surfaces of the bottom protective cylinder 1 and the plurality of intermediate protective cylinders 2. This structural design helps to reduce the resistance experienced by the reinforcing protrusion 8 during rotation.

[0021] Specifically, the bottom casing 1 and multiple intermediate casings 2 constitute the borehole wall, preventing borehole collapse during drilling. Furthermore, because the bottom casing 1 and multiple intermediate casings 2 rotate downwards, they generate almost no vibration, making it less likely to induce large-scale borehole collapse accidents in karst areas. The casing can be rotated downwards by applying external force with the torque power head configured on the top working platform, and the cutting teeth 4 cut into the rock mass synchronously with the drill bit. The reinforcing protrusion 8 effectively enhances the strength and rigidity of the bottom casing 1 and intermediate casings 2, and can effectively reduce deformation and warping of the bottom casing 1 and intermediate casings 2 by dispersing stress and absorbing energy. Moreover, during rotary drilling, the reinforcing protrusion 8 can effectively compress the internal rock mass, disrupting its integrity and facilitating subsequent drill bit advance. The tapering zone 9 facilitates the insertion of the reinforcing protrusion 8 into the rock mass.

[0022] In detail, since excessive thickness of the bottom protective sleeve 1 and the multiple intermediate protective sleeves 2 would increase the difficulty of rotating and pressing them down, the bottom protective sleeve 1 and the multiple intermediate protective sleeves 2 should not be too thick. In this embodiment, the thickness of the bottom protective sleeve 1 and the multiple intermediate protective sleeves 2 is preferably 16mm. The reinforcing protrusion 8 can enhance the strength and rigidity of the bottom protective sleeve 1 and the multiple intermediate protective sleeves 2 with almost no increase in thickness, effectively reducing the deformation and warping of the bottom protective sleeve 1 and the intermediate protective sleeves 2.

[0023] Among them, the bottom protective sleeve 1 and multiple intermediate protective sleeves 2 are made of Q345 steel plate, and the cutting teeth 4 are made of cemented carbide. The cutting teeth 4 are preferably made of YG8 (K30).

[0024] See Figure 1 , Figure 3 and Figure 5 As shown, in some embodiments, it further includes: a male connector 10, which is provided at the top of the bottom protective sleeve 1 and one end of the middle protective sleeve 2; and a female connector 11, which is provided at the other end of the middle protective sleeve 2. The connection between the male connector 10 and the female connector 11 forms the connection between the bottom protective sleeve 1 and the middle protective sleeve 2, as well as between two adjacent middle protective sleeves 2.

[0025] In this embodiment, the outer diameter of the male connector 10 is equal to the outer diameter of the bottom casing 1 and the middle casing 2, the outer diameter of the female connector 11 is equal to the inner diameter of the bottom casing 1 and the middle casing 2, and the inner diameter of the male connector 10 is equal to the outer diameter of the female connector 11, so that the inner and outer diameters of the connection are the same as the inner and outer diameters of the bottom casing 1 or the middle casing 2, thereby reducing the rotary drilling resistance.

[0026] See Figure 1 , Figure 2 , Figure 3 and Figure 5 As shown, in some embodiments, it further includes: a first groove area 3, wherein multiple first groove areas 3 are provided circumferentially at intervals on the outer peripheral surface of the male connector 10; and a connecting hole 7, wherein connecting holes 7 are provided on both the first groove areas 3 and the female connector 11. The male connector 10 and the female connector 11 are connected by high-strength bolts and the connecting holes 7. After the bottom casing 1 or the intermediate casing 2 has sunk into place, before connecting the next section of the intermediate casing 2, a clamp is first used to secure the sunken bottom casing 1 or intermediate casing 2 to prevent the bottom casing 1 or intermediate casing 2 from sinking due to its own weight. The clamp consists of two semicircles and is tightened with long bolts.

[0027] See Figure 1 , Figure 2 , Figure 3 and Figure 5As shown, in some embodiments, it further includes: a connecting protrusion 5, which is disposed at the top of the reinforcing protrusion 8; and a connecting groove, which is provided at the bottom of the reinforcing protrusion 8 to accommodate the connecting protrusion 5. The connecting protrusion 5 and the connecting groove share the torque on the high-strength bolt, thereby enhancing the service life of the high-strength bolt. Furthermore, the structural design of the connecting groove and the connecting protrusion 5 also facilitates the rapid positioning of the male connecting end 10 and the female connecting end 11.

[0028] See Figure 1 , Figure 2 , Figure 3 and Figure 5 As shown, in some embodiments, a guide portion 6 is further included, which is provided on the top of the connecting protrusion 5. The guide portion 6 facilitates the insertion of the connecting protrusion 5 into the connecting groove, reducing the difficulty of docking between the male connecting end 10 and the female connecting end 11.

[0029] See Figure 1 , Figure 3 and Figure 4 As shown, in some embodiments, it further includes: a second cutting groove area, wherein a plurality of second cutting groove areas are provided circumferentially at the bottom of the bottom sleeve 1, and the cutting teeth 4 are disposed in the second cutting groove areas. The cutting teeth 4 are disposed in the second cutting groove areas by welding, and the second cutting groove areas can increase the area of ​​the connection between the cutting teeth 4 and the bottom sleeve 1, thereby enhancing the reliability of the cutting teeth 4.

[0030] The above description is only a part or preferred embodiment of this application. Neither the text nor the drawings should limit the scope of protection of this application. All equivalent structural transformations made using the content of this application's specification and drawings under the overall concept of this application, or direct / indirect applications in other related technical fields, are included within the scope of protection of this application.

Claims

1. A borehole-supported anti-collapse structure for karst development areas, comprising a bottom casing (1) and multiple intermediate casings (2), wherein the bottom intermediate casings (2) are connected to the bottom casing (1), the multiple intermediate casings (2) are connected end to end, and the bottom end of the bottom casing (1) is provided with cutting teeth (4), characterized in that, Also includes: Reinforcing protrusions (8) are provided circumferentially on the inner side of the bottom sleeve (1) or the middle sleeve (2). The tapering area (9) is provided at the bottom of the reinforcing protrusion (8) inside the bottom sleeve (1). Also includes: Male connector (10), the top end of the bottom protective sleeve (1) and one end of the middle protective sleeve (2) are provided with the male connector (10); The female connector (11) is provided at the other end of the intermediate protective sleeve (2). Also includes: The first grooving area (3) is provided with a plurality of first grooving areas (3) at circumferential intervals on the outer peripheral surface of the male connection end (10); Connection hole (7) is provided on both the first groove area (3) and the female connection end (11); Also includes: The bottom of the bottom sleeve (1) is provided with a plurality of second cutting grooves along the circumferential direction, and the cutting teeth (4) are provided in the second cutting grooves.

2. The combination anti-sloughing structure for drilling in karst development zones according to claim 1, characterized in that, Also includes: Connecting protrusion (5), the connecting protrusion (5) is disposed at the top of the reinforcing protrusion (8); The bottom end of the reinforcing protrusion (8) is provided with a connecting groove that is adapted to the connecting protrusion (5).

3. The combination anti-sloughing structure for drilling in karst development zones according to claim 2, characterized in that, Also includes: The guide portion (6) is provided on the top of the connecting protrusion (5).

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