Hole protector for anti-floating anchor rod hole under complex geological conditions and use method
By using a hole protector to form a stable ring support structure under complex geological conditions, the problem of easy collapse of anchor bolt holes is solved, continuous drilling and centralized grouting are achieved, construction efficiency and quality are improved, and costs are reduced.
Patent Information
- Application Number
- CN202511796518.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-02
- Publication Date
- 2026-01-16
AI Technical Summary
Under complex geological conditions, anchor holes are prone to collapse during the construction of anti-buoyancy anchors, and traditional construction methods are inefficient and cannot achieve "one hole, one injection", resulting in high construction costs and extended construction period.
The borehole protector consists of a central rod, a slider, a telescopic cover, a hinge, an arc-shaped protective plate, a transmission rod, and a counterweight. The arc-shaped protective plate expands under the gravity of the counterweight, forming a stable annular support structure to prevent the borehole wall from collapsing. The telescopic cover seals the borehole opening, enabling continuous drilling and concentrated grouting.
It effectively prevents anchor hole collapse, simplifies construction process, improves construction efficiency, reduces costs, adapts to different geological conditions, and ensures construction quality and schedule.
Smart Images
Figure CN121345121A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of anchor hole protection, and in particular to a hole protector for anti-floating anchor holes under complex geological conditions and a use method thereof. BACKGROUND
[0002] In the traditional anti-floating anchor construction in the construction industry, the conventional process is mechanical drilling -> hole cleaning -> anchor installation -> grouting, but due to process organization and efficiency considerations, it is difficult to achieve "one hole one grouting", and generally a certain number of anchor holes need to be drilled before the subsequent grouting process is carried out. However, the anti-floating anchor design spacing is generally close, and the vibration generated by the subsequent drilling mechanical operation can easily disturb the formed hole wall; if the construction area has complex geological conditions such as high underground water level and loose sand layer, the stability of the hole wall itself is poor, and the collapse risk of the formed anchor hole will be greatly increased under the superimposed influence of mechanical vibration, which will lead to the failure of the early drilling and hole cleaning process, resulting in waste of rework.
[0003] In order to avoid the above hole collapse problem and ensure construction quality, the intermittent construction mode of "drilling a hole, immediately installing an anchor, and immediately grouting" is often forced to be used under complex geological conditions, but this method needs to frequently switch drilling, installation, and grouting equipment and processes, which not only seriously prolongs the overall construction period, but also causes repeated scheduling and idling of manpower, machinery, and materials, significantly increasing construction costs, and exposing the limitations of traditional technology in complex geological scenarios that efficiency and quality cannot be considered.
[0004] The hole collapse problem in anti-floating anchor construction mainly comes from two aspects: first, the continuous vibration generated by the subsequent drilling mechanical operation can easily disturb the formed hole wall, inducing hole collapse; second, the high underground water level and loose sand layer and other geological features lead to weak stability of the hole wall itself, which is more susceptible to external environmental influences and prone to hole collapse, especially in complex geological scenarios, the two types of risks are superimposed, and the problem is more prominent. SUMMARY
[0005] In order to make up for the above shortcomings, the present application provides a hole protector for anti-floating anchor holes under complex geological conditions and a use method thereof, which solves the problems of easy hole collapse and low construction efficiency of complex geological anchor holes in traditional anti-floating anchor construction.
[0006] In order to achieve the above object, the application adopts the following technical scheme: A hole protector for anti-floating anchor rod hole under complex geological conditions, comprising a middle rod, a slider, an extension cover, a joint, an arc-shaped guard plate, a transmission rod and a counterweight; the arc-shaped guard plate has several pieces, which form a complete cylinder in the closed state, and the lower part of the cylinder is pointed; the joint is arranged on the transmission rod, one end of the transmission rod is connected with the middle rod, and the other end is connected with the arc-shaped guard plate; the counterweight is fixed at the bottom of the middle rod, and drives the axial movement of the middle rod through gravity, drives the transmission rod and the joint to act, and expands or closes the arc-shaped guard plate; the slider is sleeved on the middle rod and is linked with the arc-shaped guard plate; the extension cover is installed at the top of the arc-shaped guard plate and is connected with the slider, and expands or closes synchronously with the sliding of the slider.
[0007] As a further description of the above technical scheme: the number of arc-shaped guard plates is three, and the three arc-shaped guard plates are distributed in a circumferential symmetry, and can completely fit the inner wall of the anchor rod hole after expansion.
[0008] As a further description of the above technical scheme: the joint is arranged at both ends of the transmission rod, which can flexibly adjust the angle of the transmission rod, and ensure the stable expansion or reset of the arc-shaped guard plate.
[0009] As a further description of the above technical scheme: the weight of the counterweight can be adjusted according to the depth of the anchor rod hole and the geological conditions, so as to meet the needs of the expansion of the arc-shaped guard plate driven by the self-moving middle rod.
[0010] As a further description of the above technical scheme: when the counterweight reaches the pointed end of the lower part of the arc-shaped guard plate cylinder, the pointed end supports the counterweight, and at this time the transmission rod reaches the maximum expansion diameter.
[0011] As a further description of the above technical scheme: the extension cover adopts a fan type opening and closing structure, and its opening and closing action is synchronous with the movement of the arc-shaped guard plate, and through the linkage of the slider and the middle rod, the extension cover is opened synchronously when the arc-shaped guard plate is expanded, and is closed synchronously when the arc-shaped guard plate is closed, so as to prevent sundries from falling into the hole.
[0012] As a further description of the above technical scheme: the top of the middle rod can accept external pressure, and the axial pressure or tension is applied to the top of the middle rod to forcibly drive the movement of the middle rod, and then control the expansion or closing of the arc-shaped guard plate.
[0013] As a further description of the above technical scheme: a supporting piece is further slidably connected to the middle rod, a supporting rod matched with the number of arc-shaped guard plates is connected to the supporting piece, and the supporting rod is a telescopic rod, and the distal end is fixedly connected to the top of the arc-shaped guard plate.
[0014] A use method of a hole protector for anti-floating anchor rod hole under complex geological conditions, comprising the following steps:
[0015] Step S1: Drilling and cleaning: Complete the drilling and cleaning of the anti-buoyancy anchor bolt holes at the preset hole positions;
[0016] Step S2: Lowering the hole protector and automatic hole protection: Lower the hole protector, which is in the closed state, to the bottom of the hole. With the help of the gravity of the counterweight, the central rod moves down. Through the linkage of the transmission rod and the hinge, the arc-shaped protective plate expands outward to support the hole wall. At the same time, the telescopic cover unfolds to close the hole.
[0017] Step S3: Continuous drilling and temporary hole protection: Move the work machinery to the next designed hole position and repeat steps S1 and S2 until all anchor holes in a batch are drilled and temporarily protected.
[0018] Step S4: Hole protector retrieval and subsequent construction: Pull the middle bar in sequence to close and remove the hole protectors in each hole, and then carry out anchor bolt installation and grouting operations in the anchor bolt holes that have been protected.
[0019] As a further description of the above technical solution: In step S4, the recovered hole protector, after being cleaned and maintained, can be reused for subsequent batches of the same project or for anchor hole protection operations in other construction projects.
[0020] The present invention has the following beneficial effects:
[0021] 1. In this invention, three symmetrically distributed arc-shaped protective plates are expanded and fitted to the borehole wall to form a stable ring support structure, which can effectively resist the vibration and disturbance of subsequent drilling machinery. At the same time, it is suitable for complex geological conditions such as high groundwater level and loose sand layer, avoids the natural collapse of the borehole wall, solves the problem of borehole collapse, ensures the effectiveness of the early drilling and cleaning process, and reduces rework waste. Meanwhile, the tip of the arc-shaped protective plate can accurately support the counterweight block, restrict the center rod from moving further down, and avoid the problem of abnormal transmission rod angle and excessive expansion and contraction of arc-shaped protective plates due to excessive downward movement of the center rod. This ensures that the arc-shaped protective plate forms a stable ring support structure and maximizes the anti-borehole collapse effect.
[0022] 2. In this invention, the fan-shaped telescopic cover and the arc-shaped protective plate are linked, which can achieve hole sealing without additional operation, avoid secondary hole cleaning, and further simplify the construction process. The hole protector has two modes: self-expanding counterweight and active control of top pressure. No complicated technical training is required, and ordinary construction personnel can quickly get started. Moreover, the hole protector can be reused. The weight of the counterweight can be flexibly adjusted according to geological conditions and hole depth. The setting of the support and telescopic rod further improves the adaptability of the equipment. It not only reduces the idle and repeated investment costs of manpower, machinery and materials, but also adapts to the construction needs of different complex geological scenarios, taking into account both construction efficiency and economy.
[0023] 3. This invention utilizes the temporary protective function of the hole protector to achieve a construction mode of batch drilling and centralized grouting, abandoning the traditional intermittent construction of "drilling one hole and grouting one hole", avoiding frequent equipment switching and scheduling, greatly shortening the construction period and improving the overall construction efficiency. Attached Figure Description
[0024] Figure 1 This is a front view of the closed state of the hole protector in this invention;
[0025] Figure 2 This is a front view schematic diagram of the unfolded state of the hole protector in this invention;
[0026] Figure 3 This is a schematic cross-sectional view of the hole protector in the unfolded state of the present invention;
[0027] Figure 4 This is a top cross-sectional view of the hole protector inserted into the anchor bolt hole in this invention;
[0028] Figure 5 This is a top view of the support component.
[0029] Legend:
[0030] 1. Center rod; 2. Slider; 3. Telescopic cover; 4. Hinge; 5. Arc-shaped guard plate; 6. Transmission rod; 7. Counterweight; 8. Support component. Detailed Implementation
[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0032] Example 1
[0033] Reference Figures 1-4This invention provides an embodiment of a hole protector for anti-buoyancy anchor bolt holes under complex geological conditions. The protector includes a central rod 1, a slider 2, a telescopic cover 3, a hinge 4, an arc-shaped protective plate 5, a transmission rod 6, and a counterweight 7. These components work together to form a complete hole protector structure. The arc-shaped protective plates 5 are three in number, symmetrically distributed around the circumference. When closed, they enclose a complete cylindrical structure. When expanded, they completely conform to the inner wall of the anchor bolt hole, forming a stable annular support structure. This effectively resists vibrations and disturbances from subsequent drilling machinery, preventing the hole wall from collapsing naturally. Furthermore, the lower part of the cylinder is machined into a pointed shape, allowing the hole protector to be lowered... During the process, the contact area and frictional resistance with the hole wall are reduced, allowing the hole protector to move smoothly and uniformly down along the axis of the anchor bolt hole, avoiding disturbance to the hole wall due to violent collisions or scraping between the components and the hole wall during descent. The hinges 4 are respectively set at both ends of the transmission rod 6, forming a flexible rotatable connection node. One end of the transmission rod 6 is hinged to the middle rod 1, and the other end is hinged to the inner middle of the arc-shaped guard plate 5. Through the angle adjustment function of the hinges 4, the axial movement of the middle rod 1 can be smoothly converted into the radial opening and closing movement of the arc-shaped guard plate 5, ensuring that the arc-shaped guard plate 5 fits the hole wall when expanding and resets smoothly when closing, thus ensuring the stable operation of the hole protector.
[0034] The counterweight 7 is fixedly installed on the bottom end face of the central rod 1. Its weight can be flexibly adjusted according to the geological conditions of the construction area (such as the looseness of the sand layer and the stability of the hole wall) and the design depth of the anchor bolt hole. Its core function is to provide driving force through its own gravity, so that the central rod 1 moves downward autonomously after the hole protector is lowered to the bottom of the hole, thereby triggering the linkage between the transmission rod 6 and the hinge 4 to realize the automatic expansion of the arc-shaped protective plate 5. When the counterweight 7 reaches the lower tip of the cylinder of the arc-shaped protective plate 5, the tip of the arc-shaped protective plate 5 supports the counterweight 7. At this time, the transmission rod 6 reaches the maximum expansion diameter, ensuring that the arc-shaped protective plate 5 can fully support the hole wall. This prevents the central rod 1 from continuing to move downward, which would cause the transmission rod 6 and the arc-shaped protective plate 5 to form a reverse angle, resulting in the arc-shaped protective plate 5 contracting and closing.
[0035] The slider 2 is movably sleeved in the upper area of the central rod 1, and can slide freely along the axial direction of the central rod 1. It is linked to the arc-shaped guard plate 5 through a connecting rod structure, so that the opening and closing action of the arc-shaped guard plate 5 is synchronized with the displacement of the slider 2. The telescopic cover 3 is installed on the top edge of the arc-shaped guard plate 5 and is fixedly connected to the slider 2 through a connector. It adopts a fan-shaped opening and closing structure spliced with multiple fan-shaped plates. Its opening and closing action is synchronized with the movement of the arc-shaped guard plate 5: when the arc-shaped guard plate 5 expands outward, the slider 2 moves down accordingly, driving the telescopic cover 3 to unfold to close the opening, effectively preventing external debris, scattered soil or rainwater from falling into the hole during construction and avoiding secondary hole cleaning; when the arc-shaped guard plate 5 closes inward, the slider 2 resets upward and drives the telescopic cover 3 to retract.
[0036] The top of the central rod 1 is reserved with a force-bearing end, which can accept external axial pressure or tension to form an active control mode. When the guard plate needs to be expanded or closed quickly under complex geological conditions (such as local loosening of the borehole wall or insufficient weight of the counterweight 7), the axial movement of the central rod 1 can be forced by applying pressure or lifting force to the top of the central rod 1, thereby accurately controlling the expansion range or closing timing of the arc-shaped guard plate 5, and adapting to more complex construction conditions.
[0037] Example 2
[0038] Reference Figure 5 Based on Example 1, a support member 8 is slidably connected to the central rod 1. A support member 8 is fixedly connected to a number of struts matching the number of arc-shaped guard plates 5. The struts are telescopic struts (the shortest state matches the radius of the cylinder that the arc-shaped guard plate 5 closes). The far end of the struts is fixedly connected to the top of the arc-shaped guard plate 5. The struts contract as the arc-shaped guard plate 5 unfolds and closes. When the counterweight block 7 at the lower tip of the cylinder of the arc-shaped guard plate 5 in Example 1 fails to support the counterweight block 7, the support member 8 supports the slider 2 and the top of the central rod 1, which is reserved for bearing force, to prevent the central rod 1 from continuing to move downward. At this time, the transmission rod 6 also reaches the state of maximum expansion diameter.
[0039] Example 3
[0040] In the actual construction process, the weight of the counterweight 7 is first adjusted according to the geological conditions of the construction area, such as the groundwater level, sand layer distribution, and the design depth of the anchor bolt hole, to ensure that it can drive the middle rod 1 to move down autonomously.
[0041] Then follow these steps:
[0042] Step S1: Drilling and Cleaning: Use professional drilling equipment to drill anti-buoyancy anchor bolt holes at the preset hole positions. The drilling depth and diameter meet the design requirements. After drilling, use cleaning equipment to clean the mud, sand, gravel and other debris in the hole to ensure that the hole wall is flat and the hole is clean.
[0043] Step S2: Lowering the Borehole Protector and Automatic Borehole Protection: The borehole protector, which is in a closed state (at this time, the three arc-shaped protective plates 5 are gathered together to form a cylinder with a pointed bottom), is vertically lowered to directly above the formed anchor bolt hole using a light lifting device. The position of the lifting device is adjusted so that the borehole protector is coaxial with the hole position, and then the borehole protector is slowly lowered. During the lowering process, a uniform speed is maintained (the speed does not exceed 0.5m / s) to avoid violent collision between the borehole protector and the hole wall and to prevent human disturbance of the hole wall.
[0044] When the borehole protector reaches the bottom of the borehole, the counterweight 7 at the bottom generates a downward driving force, causing the central rod 1 to move axially downward. As the central rod 1 moves downward, the axial force is converted into radial thrust through the transmission rod 6 with hinges 4 at both ends, simultaneously pushing the three arc-shaped protective plates 5 to expand outward smoothly until the outer walls of the protective plates are completely and tightly attached to the borehole wall, forming an effective ring support structure to resist the lateral pressure of the soil. At the same time, during the expansion of the arc-shaped protective plates 5, the sliding device 2 at the top is driven downward along the central rod 1 via the connecting rod. As the slider 2 moves downward, it triggers the telescopic cover 3 to unfold in a fan-shaped structure, completely covering the borehole opening and sealing it. This prevents debris and soil generated during subsequent drilling operations from falling into the hole, and also prevents rainwater from washing away the borehole wall and causing soil erosion or water accumulation in the hole during rainy weather. When the counterweight 7 reaches the lower tip of the cylindrical part of the arc-shaped guard plate 5, the tip supports the counterweight 7, and the transmission rod 6 reaches its maximum expansion diameter. The arc-shaped guard plate 5 provides optimal support to the borehole wall. At this point, the temporary protection work for the anchor bolt hole is completed.
[0045] Step S3: Continuous drilling and protection: After completing the protection of the current anchor bolt hole, move the drilling equipment and related machinery to the next designed hole position, and repeat the operations of steps S1 and S2 to complete the drilling and temporary protection of all anchor bolt holes in a batch in sequence; during this process, there is no need to frequently switch drilling and grouting equipment, thus achieving continuous construction;
[0046] Step S4: Hole Protector Retrieval and Subsequent Construction: After all anchor holes in a batch have been protected, the hole protectors in each hole are retrieved sequentially. During retrieval, the top of the central rod 1 is lifted to apply axial tension, driving the central rod 1 upward, which in turn moves the transmission rod 6 and the hinge 4, causing the arc-shaped protective plate 5 to close inward, while the telescopic cover 3 closes simultaneously. After the arc-shaped protective plate 5 is completely closed, the hole protector is removed from the hole. Immediately after the hole protector is pulled out, anti-buoyancy anchor reinforcement is installed in the hole, and grouting is then carried out. Due to the protection provided by the hole protector, the hole wall remains intact and the hole is clean, providing a strong guarantee for the quality of anchor installation and grouting. Following this process, the hole protectors are retrieved sequentially, and the anchor installation and grouting of the corresponding holes are completed.
[0047] The recovered anchor bolt protection device is cleaned to remove mud, sand and other debris adhering to the surface. The operating status of each component (such as hinge 4, transmission rod 6, support rod, etc.) is checked. After maintenance or replacement of worn or damaged components, it can be reused for subsequent batches of the same project or anchor bolt hole protection operations in other construction projects.
[0048] Furthermore, under special geological conditions, if the weight of the counterweight 7 is insufficient to drive the arc-shaped guard plate 5 to fully expand, axial pressure can be applied to the top of the central rod 1 to force the central rod 1 to move downward, thereby controlling the expansion of the arc-shaped guard plate 5; if it is necessary to retract the hole protector in advance or adjust the state of the arc-shaped guard plate 5, axial tension can be applied to the top of the central rod 1 to force the central rod 1 to move upward, thereby achieving the closure of the arc-shaped guard plate 5.
[0049] This invention enables a batch drilling and centralized grouting construction mode by providing temporary protection for anchor bolt holes with a hole protector. It eliminates the traditional intermittent construction of "drilling one hole and grouting one hole," effectively avoiding frequent equipment switching and scheduling, and improving overall construction efficiency. At the same time, the stable ring support structure formed by the arc-shaped protective plate 5 can effectively resist the vibration and disturbance of subsequent drilling machinery, prevent the hole wall from collapsing naturally, ensure construction quality, and reduce the risk of rework and construction costs.
[0050] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A hole protector for anti-buoyancy anchor bolt holes under complex geological conditions, characterized in that: The system includes a central rod (1), a slider (2), a telescopic cover (3), a hinge (4), an arc-shaped guard plate (5), a transmission rod (6), and a counterweight (7). The arc-shaped guard plate (5) consists of several pieces that, when closed, enclose a complete cylinder with a pointed lower part. The hinge (4) is mounted on the transmission rod (6), with one end connected to the central rod (1) and the other end connected to the arc-shaped guard plate (5). The counterweight (7) is fixed to the bottom of the central rod (1) and drives the central rod (1) to move axially by gravity, thereby causing the transmission rod (6) and the hinge (4) to move, thus expanding or closing the arc-shaped guard plate (5). The slider (2) is mounted on the central rod (1) and is linked to the arc-shaped guard plate (5). The telescopic cover (3) is mounted on the top of the arc-shaped guard plate (5) and is connected to the slider (2), expanding or closing synchronously with the sliding of the slider (2).
2. A hole protector for anti-buoyancy anchor bolt holes under complex geological conditions according to claim 1, characterized in that: The number of the arc-shaped guard plate (5) is three pieces. The three arc-shaped guard plates (5) are symmetrically distributed around the circumference and can completely fit the inner wall of the anchor bolt hole after expansion.
3. A hole protector for anti-buoyancy anchor bolt holes under complex geological conditions according to claim 1, characterized in that: The hinge (4) is located at both ends of the transmission rod (6), and the angle of the transmission rod (6) can be flexibly adjusted to ensure that the arc-shaped guard plate (5) expands or returns to its original position smoothly.
4. A hole protector for anti-buoyancy anchor bolt holes under complex geological conditions according to claim 1, characterized in that: The weight of the counterweight (7) can be adjusted according to the depth of the anchor hole and geological conditions to meet the needs of the central rod (1) to move down autonomously and drive the arc-shaped guard plate (5) to expand.
5. A hole protector for anti-buoyancy anchor bolt holes under complex geological conditions according to claim 4, characterized in that: When the counterweight (7) reaches the tip of the lower part of the cylindrical part of the arc-shaped guard plate (5), the tip can support the counterweight (7), and at this time the transmission rod (6) reaches the maximum extended diameter.
6. A hole protector for anti-buoyancy anchor bolt holes under complex geological conditions according to claim 1, characterized in that: The telescopic cover (3) adopts a fan-shaped opening and closing structure. Its opening and closing action is synchronized with the movement of the arc-shaped guard plate (5). It is linked with the middle rod (1) through the slider (2). It opens synchronously when the arc-shaped guard plate (5) unfolds and closes synchronously when the arc-shaped guard plate (5) closes, in order to prevent debris from falling into the hole.
7. A hole protector for anti-buoyancy anchor bolt holes under complex geological conditions according to claim 1, characterized in that: The top of the middle rod (1) can accept external pressure. By applying axial pressure or tension to the top of the middle rod (1), the middle rod (1) is forced to move, thereby controlling the expansion or closure of the arc-shaped guard plate (5).
8. A hole protector for anti-buoyancy anchor bolt holes under complex geological conditions according to claim 1, characterized in that: The central rod (1) is also slidably connected to a support member (8), and the support member (8) is connected to a number of struts matching the number of arc-shaped guard plates (5). The struts are telescopic rods, and their distal ends are fixedly connected to the top of the arc-shaped guard plate (5).
9. A method for using a hole protector for anti-buoyancy anchor bolt holes under complex geological conditions, characterized in that: Includes the following steps: Step S1: Drilling and cleaning: Complete the drilling and cleaning of the anti-buoyancy anchor bolt holes at the preset hole positions; Step S2: Lowering the hole protector and automatic hole protection: Lower the hole protector, which is in a closed state, to the bottom of the hole. Drive the middle rod (1) to move down with the help of the gravity of the counterweight (7). Through the linkage of the transmission rod (6) and the hinge (4), the arc-shaped guard plate (5) expands outward to support the hole wall. At the same time, the telescopic cover (3) is opened to close the hole. Step S3: Continuous drilling and temporary hole protection: Move the work machinery to the next designed hole position and repeat steps S1 and S2 until all anchor holes in a batch are drilled and temporarily protected. Step S4: Hole protector retrieval and subsequent construction: Pull the middle bar (1) in sequence to close and remove the hole protectors in each hole, and then carry out anchor bolt installation and grouting operations in the anchor bolt holes that have been protected.
10. The method of using a hole protector for anti-buoyancy anchor bolt holes under complex geological conditions according to claim 9, characterized in that: In step S4, the recovered hole protector, after cleaning and maintenance, can be reused for subsequent batches of the same project or for anchor hole protection operations in other construction projects.