A method for forming a square pile hole in hard rock formations

Abstract

This invention relates to the field of square pile construction in hard rock strata, and particularly to a method for forming square pile holes in hard rock strata. A loop-shaped isolation channel is formed by a first sequence hole and a second sequence hole, isolating the rock strata in the non-hole-forming area from the rock strata to be excavated area. During excavation of the rock strata to be excavated, disturbance to the non-hole-forming area is significantly reduced. Compared to blasting methods, this method avoids internal damage and structural changes in the non-hole-forming area, thus ensuring the stability of the rock strata structure and providing good support for the cast-in-place square pile, guaranteeing the construction quality of the square pile. A precast tube is inserted into the first sequence hole to fill it. When drilling the second sequence hole, the precast tube guides the drill rod of the down-the-hole drill, preventing the drill rod from deviating. During construction, the second sequence hole can be drilled quickly, accelerating the construction process.

Description

Technical Field

[0001] This invention relates to the field of square pile construction in hard rock formations, and particularly to a method for forming square pile holes in hard rock formations. Background Technology

[0002] Square pile drilling technology refers to the drilling method used in foundation or slope engineering to construct piles with square cross-sections, such as anti-slide piles and support piles. Compared with traditional circular piles, square piles have stronger shear resistance and are especially suitable for landslide control and deep foundation pit support projects. Currently, the main method for drilling square piles in hard rock strata (where the saturated uniaxial compressive strength of the rock strata is greater than 60 MPa) is manual excavation, including cyclic manual excavation to a depth of 80-100 cm, protective drilling downwards, or using a water-cooled drill to excavate to a depth of about 60 cm each time. In rock strata where the saturated uniaxial compressive strength is less than 60 MPa, rotary drilling can be used to drill square piles, but the cost is about twice that of manually excavated piles. Using blasting construction methods can improve excavation efficiency.

[0003] However, blasting causes significant disturbance to the rock strata in non-hole-forming areas, which can easily lead to hidden damage and changes in the rock strata structure, resulting in changes in the rock strata's support force on the square piles and causing deviations between the actual performance and design performance of the square piles. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies where blasting methods cause significant disturbance to the rock strata in non-hole-forming areas during the construction of square pile holes, and to provide a method for forming square pile holes in hard rock strata.

[0005] This invention provides a method for forming square pile holes in hard rock strata, comprising the following steps:

[0006] S1: Surveying and setting out: According to the design requirements, set out the location of the square pile holes in the hard rock layer and mark the outline of the square piles; S2: Opening the first sequence holes: Using a down-the-hole drill, open a number of first sequence holes at intervals along the outline of the square pile; the depth of the first sequence holes is greater than or equal to the design depth of the square pile holes. S3: Insert precast tube: Insert a precast tube into the first sequence hole to support the hole wall of the first sequence hole; S4: Opening a second sequence hole: On the outline of the square pile, between two adjacent first sequence holes, a second sequence hole is opened using a down-the-hole drill. The depth of the second sequence hole is greater than or equal to the design depth of the square pile hole. The sidewalls of the first sequence hole and the sidewalls of the second sequence hole are connected to form a loop-shaped isolation channel, which isolates the rock strata in the non-hole area from the rock strata in the area to be excavated. S5: Fill with foam rod: Fill the second sequence hole with foam rod; S6: Opening split holes: Open several split holes in the rock strata of the area to be excavated; the depth of the split holes is greater than or equal to the design depth of the square pile holes. S7: Forming square pile holes: A splitting rod is inserted into the splitting hole to split the rock strata in the area to be excavated in sections from shallow to deep to form square pile holes.

[0007] Preferably, in step S4, the minimum distance between the hole walls of adjacent first sequential holes is d, where d is equal to the diameter of the first sequential hole and the diameter of the first sequential hole is equal to the diameter of the second sequential hole.

[0008] Preferably, in step S4, the drilling depth of the first sequence hole is greater than the design depth of the square pile hole; the drilling depth of the second sequence hole is greater than the design depth of the square pile hole.

[0009] Preferably, in step S2, before drilling the first sequence hole, a guide frame is set on the hard rock layer. The guide frame is equipped with a connector and several guide tubes, so that the guide tubes are located above the first sequence hole, and the drill rod of the down-the-hole drill passes through the guide tubes.

[0010] Preferably, a plurality of the guide tubes are arranged at intervals on the guide frame, and the center distance between adjacent guide tubes is 2d.

[0011] Preferably, in step S6, a water-cooled drill is used to create the splitting hole.

[0012] Preferably, in step S7, before the splitting rod is inserted into the splitting hole, the prefabricated tube is pulled out from the first sequence hole, and the first sequence hole is filled with foam rods.

[0013] Preferably, in step S3, the prefabricated pipe is a steel pipe.

[0014] Preferably, in step S6, the splitting hole includes a central hole and several circumferential holes. The central hole is located in the middle of the square pile hole, and the several circumferential holes are arranged in a ring around the circumference of the central hole.

[0015] Preferably, the circumferential hole is located on the diagonal of the outline of the square pile.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention provides a method for forming square pile holes in hard rock strata. By drilling a first sequence hole and a second sequence hole, a loop-shaped isolation channel is formed, effectively isolating the rock strata in the non-hole-forming area from the rock strata in the area to be excavated. When excavating the area to be excavated, the disturbance to the rock strata in the non-hole-forming area can be significantly reduced. Compared with traditional blasting methods, this method can avoid internal damage and structural changes in the rock strata, ensuring the structural stability of the rock strata in the non-hole-forming area, thereby providing good support for the subsequent cast square piles and ensuring construction quality.

[0017] 2. This invention provides a method for forming square pile holes in hard rock strata. During construction, a down-the-hole drill is used for drilling, improving construction efficiency. When drilling the first sequence hole, the rock strata on both sides provide support for the drill rod, ensuring hole position accuracy. When drilling the second sequence hole, since the two sides are first sequence holes, the drill rod is prone to displacement, affecting hole position accuracy. Therefore, a precast tube is first inserted into the first sequence hole for filling, and the precast tube guides the drill rod to prevent displacement, ensuring the accuracy of the second sequence hole, while also accelerating drilling speed and improving construction efficiency.

[0018] 3. The present invention provides a method for forming square pile holes in hard rock strata. After the second sequence hole is drilled, foam rods are filled into the hole to prevent stone chips and debris from entering the hole and avoid affecting the splitting effect of the rock strata in the subsequent excavation area.

[0019] 4. The present invention provides a method for forming square pile holes in hard rock strata. When splitting the rock strata in the area to be excavated to form square pile holes, a segmented splitting method from shallow to deep is adopted. The rock strata are first divided into several segments along the vertical direction, and the splitting operation is carried out sequentially from the shallow segment to the deep segment, which reduces the difficulty of a single splitting, facilitates the crushing and hoisting of rock blocks, and improves construction accuracy and efficiency. Attached Figure Description

[0020] Figure 1 This is a schematic flowchart of a method for forming square pile holes in hard rock strata according to the present invention. Figure 2 This is a schematic diagram of the construction of the first hole in a method for forming square pile holes in hard rock strata according to the present invention; Figure 3 This is a construction schematic diagram of the second hole in a method for forming square pile holes in hard rock strata according to the present invention; Figure 4 This is a construction schematic diagram of the second hole in a method for forming square pile holes in hard rock strata according to the present invention; Figure 5 This is a partially enlarged structural schematic diagram of the insertion of a prefabricated pipe in a method for forming square pile holes in hard rock strata according to the present invention. Figure 6 This is a partially enlarged structural diagram of the foam-filled rod used in a method for forming square pile holes in hard rock strata according to the present invention. Figure 7 This is a schematic diagram of the guide frame for a method of forming square pile holes in hard rock strata according to the present invention; Figure 8 This is a partially enlarged structural diagram of the foam filling rod used in a method for forming square pile holes in hard rock strata according to Embodiment 2 of the present invention.

[0021] Marked in the image: 1-Hard rock stratum, 11-Rock stratum in the area to be excavated, 12-Rock stratum in the non-hole-forming area, 2-Outline of square pile, 3-First sequence hole, 4-Second sequence hole, 5-Split hole, 6-Precast pipe, 7-Foam rod, 8-Guide frame, 81-Guide pipe, 82-Connecting part. Detailed Implementation

[0022] The present invention will now be described in further detail with reference to specific embodiments. However, this should not be construed as limiting the scope of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0023] Unless otherwise specified, the use of terms such as "upper," "lower," "left," "right," "center," "inner," and "outer" to indicate orientation or positional relationships in the description of specific embodiments of the present invention is based on the orientation or positional relationships shown in the accompanying drawings, or the orientation or positional relationship in which the product / equipment / device is typically placed during use. These terms are merely for the purpose of facilitating the description of the present invention or simplifying the description in specific embodiments, enabling those skilled in the art to quickly understand the solution, and do not indicate or imply that a particular device / component / element must have a specific orientation, or be constructed and operated in a specific positional relationship. Therefore, they should not be construed as limitations on the present invention.

[0024] Furthermore, the use of terms such as "horizontal," "vertical," "suspended," and "parallel" does not imply that the corresponding device / component / element must be absolutely horizontal, vertical, suspended, or parallel, but rather that it can be slightly tilted or have a deviation. For example, "horizontal" merely means that its direction is more horizontal relative to "vertical," not that the structure must be completely horizontal, but that it can be slightly tilted. Alternatively, it can be simplified to mean that the corresponding device / component / element, when set in a "horizontal," "vertical," "suspended," or "parallel" direction, can have an error / deviation of ±10% relative to the corresponding direction, more preferably within ±8%, more preferably within ±6%, more preferably within ±5%, and more preferably within ±4%. As long as the corresponding device / component / element is within the error / deviation range, it can still achieve its function in the present invention.

[0025] Furthermore, the use of terms such as "first," "second," and "third" in terminology is merely for distinguishing descriptions of identical or similar components and should not be interpreted as emphasizing or implying the relative importance of a particular component.

[0026] Furthermore, in the description of the embodiments of the present invention, "several", "more than", and "a number of" represent at least two. The number can be any number, such as 2, 3, 4, 5, 6, 7, 8, or 9, and can even exceed nine.

[0027] Furthermore, in the description of the technical solution of this invention, unless otherwise explicitly specified / limited / restricted, the terms "set up," "install," "connect," "link," "provided with," "laid out," and "arranged" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to common connection methods in the art, such as welding, riveting, bolting, and threaded connections. Such connections can be mechanical, electrical, or communication connections; they can be direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components.

[0028] Example 1 like Figures 1-8 As shown, a method for forming square pile holes in hard rock formations comprises the following steps: S1: Surveying and setting out: According to the design requirements, set out the location of the square pile holes in the hard rock layer 1 and mark the outline of the square pile 2; S2: Opening the first sequence hole 3: Mark the positions of several first sequence holes 3 on the outline line 2 of the square pile. The positions of several first sequence holes 3 are arranged at intervals along the outline line 2 of the square pile, so that adjacent first sequence holes 3 are set at intervals. The first sequence holes 3 are opened using a down-the-hole drill. The depth of the first sequence hole 3 is greater than or equal to the design depth of the square pile hole. S3: Insert precast tube 6: Insert precast tube 6 into the first sequence hole 3; S4: Opening the second sequence hole 4: Mark the positions of several second sequence holes 4 on the outline line 2 of the square pile. The second sequence holes 4 are located between adjacent first sequence holes 3. The second sequence holes 4 are opened using a down-the-hole drill. The depth of the second sequence hole 4 is greater than or equal to the design depth of the square pile hole. The sidewall of the first sequence hole 3 and the sidewall of the second sequence hole 4 are connected to form a loop-shaped isolation channel. The loop-shaped isolation channel isolates the rock stratum 12 in the non-hole area and the rock stratum 11 in the area to be excavated. S5: Fill with foam rod 7: Fill the second sequence hole 4 with foam rod 7; S6: Opening split holes 5: Mark the positions of several split holes 5 in the rock stratum 11 in the area to be excavated, and open split holes 5; the depth of split holes 5 is greater than or equal to the design depth of the square pile hole. S7: Forming square pile holes: A splitting rod is inserted into the splitting hole 5 to split the rock strata 11 in the area to be excavated from shallow to deep to form square pile holes.

[0029] A loop-shaped isolation channel is formed by connecting the sidewall of the first sequence hole 3 with the sidewall of the second sequence hole 4. This loop-shaped isolation channel isolates the non-hole-forming rock stratum 12 from the rock stratum 11 to be excavated. When excavating the rock stratum 11 to be excavated, it can significantly reduce the disturbance to the non-hole-forming rock stratum 12. Compared with blasting construction, it can avoid internal damage and changes in the rock stratum structure of the non-hole-forming rock stratum 12, thereby ensuring the structural stability of the non-hole-forming rock stratum 12. This allows the non-hole-forming rock stratum 12 to provide good support for the cast-in-place square pile, ensuring the construction quality of the square pile.

[0030] In terms of construction technology, down-the-hole drilling is adopted to improve construction efficiency. When drilling the first sequence hole 3, the rock strata on both sides of the first sequence hole 3 can support the drill rod, thus ensuring the construction accuracy of the first sequence hole 3. When drilling the second sequence hole 4, since the second sequence hole 4 is flanked by the first sequence holes 3, the drill rod is prone to deviation when the down-the-hole drill is directly lowered, which makes it impossible to guarantee the positional accuracy of the second sequence hole 4. Therefore, a prefabricated pipe 6 is inserted into the first sequence hole 3 to fill it. When drilling the second sequence hole 4, the drill rod of the down-the-hole drill is guided by the prefabricated pipe 6, thus avoiding the deviation of the drill rod. During construction, the second sequence hole 4 can be drilled quickly, which speeds up the construction process.

[0031] After drilling the second sequence hole 4, foam rods 7 are filled into the second sequence hole 4 to prevent stone chips and debris from filling the second sequence hole 4 and affecting the splitting effect of the rock strata 11 in the area to be excavated.

[0032] When splitting the rock strata 11 in the area to be excavated from shallow to deep to form square pile holes, the rock strata 11 in the area to be excavated is first divided into multiple segments in the vertical direction. The rock strata 11 in the area to be excavated is split in sequence from the shallow segment to the deep segment, which reduces the difficulty of splitting the rock strata, makes it easier to lift the broken rock out of the square pile hole, and improves the construction accuracy.

[0033] Specifically, the outline of the square pile 2 is a square with a side length of 250cm.

[0034] In one or more embodiments, in S4, the minimum distance between the walls of adjacent first sequence holes (3) is d, where d is equal to the diameter of the first sequence hole 3 and the diameter of the first sequence hole 3 is equal to the diameter of the second sequence hole 4. Specifically, d is 15cm. When the diameter of the first sequence hole 3 is equal to the diameter of the second sequence hole 4 and the minimum distance is equal to the diameter of the first sequence hole 3, the first sequence hole 3 and the second sequence hole 4 can be connected after drilling, so that the loop-shaped isolation channel formed by the first sequence hole 3 and the second sequence hole 4 can better isolate the rock strata 12 in the non-hole area and the rock strata 11 in the area to be excavated, and better reduce the disturbance of the rock strata 12 in the non-hole area during splitting construction, thus ensuring the construction quality.

[0035] In one or more embodiments, in S4, the drilling depth of the first sequence hole 3 is greater than the design depth of the square pile hole; the drilling depth of the second sequence hole 4 is greater than the design depth of the square pile hole. When carrying out splitting construction, it can better avoid disturbing the rock strata 12 in the non-hole area and facilitate splitting operation at the bottom of the square pile hole. Specifically, the drilling depth of the first sequence hole 3 is 5cm greater than the design depth of the square pile hole, and the drilling depth of the second sequence hole 4 is 5cm greater than the design depth of the square pile hole.

[0036] In one or more embodiments, in S2, before the down-the-hole drill opens the first sequence hole 3, a guide frame 8 is set on the hard rock layer 1. The guide frame 8 is equipped with a connector and several guide tubes 81, so that the guide tubes 81 are located above the first sequence hole 3, and the drill rod of the down-the-hole drill passes through the guide tubes 81. Specifically, a row of guide tubes 81 are arranged on the guide frame 8, with adjacent guide tubes 81 spaced apart. A connecting part 82 is provided on the guide frame 8, which is used to connect with the fixing bolts pre-embedded on the hard rock layer 1, so that the guide frame 8 is fixed on the hard rock layer 1. After the guide frame 8 is fixed, the guide tubes 81 are located above the first sequence hole 3 and are coaxial with the first sequence hole 3. When drilling the first sequence hole 3, the drill rod passes through the guide tubes 81. Through the limiting effect of the guide frame 8, the hole position can be prevented from shifting when drilling the first sequence hole 3, thereby ensuring drilling accuracy and improving drilling efficiency.

[0037] In an optional embodiment, a number of guide tubes 81 are arranged at intervals on the guide frame 8, and the center-to-center distance between adjacent guide tubes 81 is 2d. Specifically, they are located on the same side of the square pile outline 2, and the center-to-center distance between adjacent guide tubes 81 is 30cm, so that after the second sequence hole 4 is drilled, the first sequence hole 3 can be connected with the second sequence hole 4 to form a loop-shaped isolation channel, thereby isolating the rock strata 12 in the non-drilling area and the rock strata 11 in the area to be excavated.

[0038] In one or more embodiments, in S6, a water-cooled drill is used to open the splitting hole 5, which can ensure the drilling accuracy of the splitting hole 5 and ensure the splitting effect of the rock strata 11 in the area to be excavated.

[0039] In one or more embodiments, in S3, the precast pipe 6 is a steel pipe, and the drill bit of the down-the-hole drill is located between the two steel pipes and guided by the steel pipes, thereby preventing the drill bit of the down-the-hole drill from deviating.

[0040] In one or more embodiments, in S6, the splitting hole 5 includes a central hole and several circumferential holes. The central hole is located in the middle of the square pile hole, and the several circumferential holes are arranged in a ring around the central hole. Specifically, the splitting hole 5 is a circular hole with a diameter of 20 cm. The circumferential holes are evenly distributed around the central hole, and all the circumferential holes are opened on the rock stratum 11 in the area to be excavated. After the splitting rod is inserted into the splitting hole 5 to perform the splitting operation, the splitting rod can break the rock stratum 11 in the area to be excavated. The splitting rod is supplied with high-pressure oil by a hydraulic power station, which is transmitted to the oil cylinder in the rod body through the oil pipe. This pushes the wedge block in the middle of the rod body to move downward, thereby opening the outer wedge blocks on both sides and generating a huge lateral expansion force, causing the rock or concrete on both sides of the hole wall to be cracked from the inside. The number of splitting holes 5 is five, consisting of one central hole and four circumferential holes.

[0041] In an optional embodiment, the circumferential hole is located on the diagonal of the square pile outline 2; specifically, the circumferential hole is located on the line connecting the corner and the center of the square pile outline 2, and the circumferential hole is located at the midpoint of the line.

[0042] This embodiment describes a method for forming square pile holes in hard rock strata. During construction, a first sequence hole 3 is drilled using a down-the-hole drill (DHD) and a steel pipe adapted to the DHD is inserted into it. When drilling the second sequence hole 4, the drill rod of the DHD is guided by the steel pipe, preventing the second sequence hole 4 from shifting position. This allows the first sequence hole 3 and the second sequence hole 4 to quickly form a loop-shaped isolation channel separating the non-hole-forming rock strata 12 from the rock strata 11 to be excavated. Subsequently, a splitting hole 5 is drilled to split the rock strata 11 to be excavated, thus forming the square pile hole. This avoids the use of blasting to excavate the square pile hole, reducing disturbance to the non-hole-forming rock strata 12 and ensuring its stability. This provides stable support for the square pile, ensuring the quality of the formed square pile. This method also improves the efficiency of square pile formation in hard rock strata and reduces drilling costs.

[0043] Example 2 This embodiment provides a method for forming square pile holes in hard rock formations. The method is largely the same as that in Embodiment 1. The difference from Embodiment 1 is that, in S7, before the splitting rod is inserted into the splitting hole 5, the precast pipe 6 is pulled out from the first sequence hole 3, and the first sequence hole 3 is filled with foam rods 7.

[0044] By filling the first sequence hole 3 with foam rods 7, the filling of the first sequence hole 3 with stone chips and debris is prevented from affecting the splitting effect of the rock stratum 11 in the area to be excavated; the foam rods 7 have strong deformation and buffering capacity, which can further prevent the rock stratum 12 in the non-hole area from being disturbed during the splitting construction, and provide lateral displacement space for the rock stratum, which is convenient for splitting.

[0045] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for forming square pile holes in hard rock strata, characterized in that, Includes the following steps: S1: Surveying and setting out: According to the design requirements, the location of the square pile hole is set out in the hard rock layer (1), and the outline of the square pile is marked (2); S2: Opening the first sequence hole (3): Using a down-the-hole drill, several first sequence holes (3) are opened at intervals along the outline of the square pile (2); the depth of the first sequence hole (3) is greater than or equal to the design depth of the square pile hole; S3: Insert precast tube (6): Insert precast tube (6) into the first sequence hole (3) to support the hole wall of the first sequence hole (3); S4: Opening a second sequence hole (4): On the outline line (2) of the square pile, between two adjacent first sequence holes (3), a second sequence hole (4) is opened using a down-the-hole drill. The depth of the second sequence hole (4) is greater than or equal to the design depth of the square pile hole. The sidewall of the first sequence hole (3) and the sidewall of the second sequence hole (4) are connected to form a loop-shaped isolation channel, which isolates the rock strata (12) in the non-hole area and the rock strata (11) in the area to be excavated. S5: Fill with foam rod (7): Fill the second hole (4) with foam rod (7); S6: Opening split holes (5): Opening several split holes (5) in the rock strata (11) of the area to be excavated; the depth of the split holes (5) is greater than or equal to the design depth of the square pile hole; S7: Forming square pile holes: A splitting rod is inserted into the splitting hole (5) to split the rock strata (11) in the area to be excavated from shallow to deep to form square pile holes.

2. The method for forming square pile holes in hard rock strata according to claim 1, characterized in that, In S4, the minimum distance between the holes of adjacent first sequence holes (3) is d, where d is equal to the diameter of the first sequence hole (3) and the diameter of the first sequence hole (3) is equal to the diameter of the second sequence hole (4).

3. A method for forming square pile holes in hard rock strata according to claim 1, characterized in that, In S4, the drilling depth of the first sequence hole (3) is greater than the design depth of the square pile hole; the drilling depth of the second sequence hole (4) is greater than the design depth of the square pile hole.

4. A method for forming square pile holes in hard rock strata according to claim 1, characterized in that, In S2, before drilling the first sequence hole, a guide frame (8) is set on the hard rock layer (1). The guide frame (8) is equipped with a connector and several guide tubes (81) so that the guide tubes (81) are located above the first sequence hole (3) and the drill rod of the down-the-hole drill passes through the guide tubes (81).

5. A method for forming square pile holes in hard rock strata according to claim 4, characterized in that, Several guide tubes (81) are arranged at intervals on the guide frame (8), and the center distance between adjacent guide tubes (81) is 2d.

6. A method for forming square pile holes in hard rock strata according to claim 1, characterized in that, In S6, a water-cooled drill is used to open a splitting hole (5).

7. A method for forming square pile holes in hard rock strata according to claim 1, characterized in that, In S7, before the splitting rod is inserted into the splitting hole (5), the prefabricated tube (6) is pulled out from the first sequence hole (3), and the first sequence hole (3) is filled with foam rods (7).

8. A method for forming square pile holes in hard rock strata according to claim 1, characterized in that, In S3, the prefabricated pipe (6) is a steel pipe.

9. A method for forming square pile holes in hard rock strata according to claim 1, characterized in that, In S6, the splitting hole (5) includes a central hole and several circumferential holes. The central hole is located in the middle of the square pile hole, and the several circumferential holes are arranged in a ring around the circumference of the central hole.

10. A method for forming square pile holes in hard rock strata according to claim 9, characterized in that, The circumferential hole is located on the diagonal of the outline (2) of the square pile.

Images