Hole guiding method suitable for diagonal bracing construction of bed rock above pit bottom of foundation pit

Abstract

The invention discloses a hole guiding method suitable for diagonal bracing construction of bed rock above the bottom of a foundation pit. The hole guiding method comprises the steps that a down-the-hole hammer of a down-the-hole drill is used for obliquely and downwards drilling a guiding hole in the position, where a diagonal bracing pipe is arranged, of a rock stratum; after the down-the-hole hammer drills and digs to a certain depth of the rock stratum, an anti-collapse device is installed and fixed at the hole opening of the guide hole, and a water injection pipe is arranged in the guide hole; the down-the-hole hammer continues to drill downwards until drilling of the guide hole is completed, in the process, rock debris at the bottom of the guide hole is cleaned in a discontinuous air blowing mode, so that the rock debris is discharged from a debris discharging hole, and water is continuously injected into the guide hole through a water injection pipe to control dust; the anti-collapse device and the down-the-hole hammer are recycled, and an inclined supporting pipe is installed in the guide hole; the grouting pipe is installed in the inclined supporting pipe, and the gap between the inclined supporting pipe and the grouting pipe and the gap between the inclined supporting pipe and the guide hole are filled; and grouting operation is conducted through the grouting pipe. The method has the advantage that the hole guiding problem of diagonal bracing construction of bed rock above the bottom of the foundation pit is effectively solved.

Description

Technical Field

[0001] The invention relates to the technical field of diagonal bracing construction, in particular to a hole-guiding method suitable for diagonal bracing construction with bedrock above a foundation pit bottom. Background Art

[0002] At present, the main form of foundation pit support is horizontal support. However, with the rapid development of foundation pit support in recent years, many foundation pits are no longer limited to horizontal support as a support form, but adopt inclined support with faster construction efficiency. The existing inclined support forms are mainly divided into inclined supports with the bottom of the support inserted into the soil to a certain depth and inclined throw supports with the bottom of the support connected to the basement floor or pier. Among them, the inclined throw supports have the problems of secondary excavation and too many post-pouring strips. Therefore, the inclined support system has made great progress in recent years. The current technology for sinking inclined supports mainly adopts static pressure, and is mainly suitable for soft soil layers. However, when the inclined support piles are in hard soil layers or bedrock formations, when static pressure is used, there are major problems in construction, and it is generally difficult to effectively sink the piles. At present, for areas with hard soil layers, diagonal bracing can be constructed by driving holes to sink piles, or when the bedrock is buried deep and serves as the diagonal bracing bearing layer, effective pile sinking can also be achieved through vibration pressure. However, for situations where there is broken bedrock above the pit bottom, there is currently no suitable method to sink the diagonal brace below the pit bottom to effectively play the role of diagonal bracing in diagonal support. The biggest problem with diagonal bracing piles in areas with bedrock above the pit bottom is how to drill holes. Currently, drilling holes in bedrock is mostly limited to vertical drilling, while oblique drilling is rarely used. This is mainly because when drilling oblique holes, the bedrock within the shallow 2m range is prone to collapse due to fragmentation, causing the down-the-hole hammer drill rod to be stuck by gravel and unable to further operate, making subsequent drilling more difficult. Summary of the Invention

[0003] The purpose of the present invention is to provide a drilling method for inclined bracing construction where bedrock exists above the bottom of a foundation pit based on the above-mentioned deficiencies in the prior art. This method effectively solves the problem of inclined drilling where bedrock exists above the bottom of a foundation pit by using a down-the-hole hammer to drill holes, and then uses a manipulator to sink the steel pipe to the designed depth. This overcomes the difficulty that the inclined bracing steel pipe cannot be effectively sunk into the bedrock, thereby improving the range of strata applicable to the inclined bracing.

[0004] The purpose of the present invention is achieved by the following technical solutions: A drilling method suitable for diagonal bracing construction in which bedrock exists above the bottom of a foundation pit, the method comprising: S1: Using a down-the-hole hammer of a down-the-hole drill, a pilot hole is drilled obliquely downward at the location where the diagonal support pipe is set in the rock formation; S2: After the down-the-hole hammer drill has excavated to a certain depth in the rock formation, an anti-collapse device is installed and fixed at the opening of the pilot hole, and a water injection pipe is set in the pilot hole; The anti-collapse device is provided with a chip removal hole on one side thereof close to the retaining pile, one end of the water injection pipe is located in the introduction hole, and the other end passes through the chip removal hole and extends to the outside of the anti-collapse device; S3: The down-the-hole hammer continues to drill downward until the pilot hole is drilled. During this process, intermittent air blowing is used to clean the rock debris at the bottom of the pilot hole so that the rock debris is discharged from the chip removal hole. Water is continuously injected into the pilot hole through the water injection pipe to control dust. S4: Recovering the anti-collapse device and the down-the-hole hammer, and installing the diagonal support pipe in the guide hole; S5: installing a grouting pipe in the diagonal bracing pipe and filling the gap between the diagonal bracing pipe and the grouting pipe and between the diagonal bracing pipe and the lead hole; S6: Utilize the grouting pipe to perform grouting operation.

[0005] In step S1, before drilling the guide hole, the shallow soil layer, residual soil and fully weathered rock or broken and diggable strongly weathered rock are removed, the site is leveled, and a rock chip collection pit is excavated near the position where the diagonal support pipe is set in the rock layer. The rock chip collection pit is set close to the retaining pile.

[0006] In step S2, the installation and fixing method of the anti-collapse device is as follows: The anti-collapse casing of the anti-collapse device is installed at the orifice of the guide hole, and a sealing plate is set on the top of the anti-collapse casing, wherein the sealing plate is provided with a through hole allowing the drill rod of the down-the-hole drill to pass through; concrete is poured at the orifice of the guide hole to fix the anti-collapse casing at the orifice of the guide hole.

[0007] In step S3, an air compressor is used to perform intermittent air blowing, so that the rock chips are discharged from the chip discharge hole and collected through the rock chip collection pit.

[0008] In step S4, a robot is used to insert the diagonal bracing tube into the wall of the guide hole. When the diagonal bracing tube is inserted to the bottom, vibration pressure is applied in time periods and multiple times. The bottom end of the diagonal bracing tube is sealed by a bottom sealing steel plate. Grouting holes are provided on the diagonal bracing tube and the bottom sealing steel plate, and the grouting holes of the diagonal bracing tube are sealed by anti-blocking foam.

[0009] In step S5, rock cuttings are used to fill the gaps between the diagonal bracing pipe and the grouting pipe and between the diagonal bracing pipe and the lead hole.

[0010] In step S6, during grouting, ensure that the slurry flows from the outer wall of the diagonal support pipe along the hole wall of the lead hole to the hole mouth of the lead hole.

[0011] The advantages of the present invention are: effectively solving the problem of drilling holes in the construction of inclined braces when there is bedrock above the bottom of the foundation pit, and then solving the problem that piles cannot be driven in the bedrock above the bottom of the foundation pit during the construction of inclined braces (piles cannot be driven to the designed depth by static pressure or conventional drilling methods), improving the application range of the inclined brace (can be used when there is bedrock above the bottom of the foundation pit), solving the problem that the cantilever support structure cannot be used and the horizontal support cannot be used due to high requirements for surrounding environmental protection, having little impact on the surrounding environment, being environmentally friendly, and having significant comprehensive effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 Schematic cross-section of step S3 of the hole-guiding method for diagonal bracing construction in which bedrock exists above the bottom of a foundation pit according to the present invention; Figure 2 Schematic cross-section of step S5 of the hole-guiding method for diagonal bracing construction in which bedrock exists above the bottom of a foundation pit according to the present invention; like Figures 1 and 2 As shown, the marks in the figure represent: Down-the-hole hammer 1, drill rod 2, guide hole 3, diagonal support pipe 4, cuttings collection pit 5, anti-collapse casing 6, sealing plate 7, chip discharge hole 8, water injection pipe 9, bottom sealing steel plate 10, grouting hole 11, retaining piles 12, foundation pit bottom 13, rock layer 14, and cuttings 15. DETAILED DESCRIPTION

[0013] The features of the present invention and other related features are further described in detail below through embodiments in conjunction with the accompanying drawings to facilitate understanding by those skilled in the art: Example: Figures 1 and 2 As shown, this embodiment relates to a hole-guiding method suitable for diagonal bracing construction where bedrock exists above the bottom of a foundation pit. The method mainly includes the following steps: S1: using the down-the-hole hammer 1 of the down-the-hole drill to drill a pilot hole 3 obliquely downward at the location where the diagonal support pipe 4 is provided in the rock stratum 14 .

[0014] In this embodiment, a down-the-hole drill rig includes a down-the-hole hammer 1 and a drill rod 2. The down-the-hole hammer 1 and drill rod 2 are connected, and the drill rod 2 can be extended. The down-the-hole drill rig drives the drill rod 2 to rotate, thereby driving the down-the-hole hammer 1 to rotate together, used to drill the rock stratum 14 on the bottom 13 of the foundation pit. The appropriate model of down-the-hole hammer 1 is selected based on the diameter of the diagonal support tube 4, ensuring that the diameter of the pilot hole 3 drilled by the down-the-hole hammer 1 is larger than the diameter of the diagonal support tube 4. Before drilling the pilot hole 3, an excavator is used to remove the shallow soil layer (rock stratum 14), residual soil, and fully weathered rock or broken and excavable highly weathered rock. The site is leveled, and a rock debris collection pit 5 is excavated near the location of the diagonal support tube 4 in the rock stratum 14. The rock debris collection pit 5 is located near the retaining pile 12 and has a depth of 0.5 meters. The rock debris collection pit 5 is used to collect rock debris 15 generated by the down-the-hole hammer 1 drilling the rock stratum 14.

[0015] S2: After the down-the-hole hammer 1 drills to a certain depth (2 m) in the rock layer 14 , an anti-collapse device is installed and fixed at the opening of the pilot hole 3 , and a water injection pipe 9 is set in the pilot hole 3 .

[0016] In this embodiment, the anti-collapse device includes an anti-collapse casing 6 and a sealing plate 7. The diameter of the anti-collapse casing 6 should be slightly smaller than the diameter of the guide hole 3 and its length should be no less than 1.5 meters. The bottom of the anti-collapse casing 6 is located within the opening of the guide hole 3, and the top of the anti-collapse casing 6 extends beyond the opening of the guide hole 3. The anti-collapse casing 6 has a horizontal chip removal hole 8 on its side near the retaining pile 12 for removing rock cuttings 15. The sealing plate 7 is located at the top of the anti-collapse casing 6 and has a through hole for the drill pipe 2 of the down-the-hole drill. One end (the bottom end) of the water injection pipe 9 is located within the guide hole 3 and above the down-the-hole hammer 1, while the other end (the top end) extends through the chip removal hole 8 to the outside of the anti-collapse casing 6. Specifically, the down-the-hole hammer 1 uses low power to drill holes in the shallow 2m depth range. Due to the relatively fragmented bedrock in the shallow area, the holes formed in this shallow range are irregular. After the drilling operation within this 2m depth range is completed, an anti-collapse casing 6 is inverted at the mouth of the drilling hole 3. After the anti-collapse casing 6 is placed at the mouth of the drilling hole 3, concrete is poured to seal and fill the collapsed area (the concrete is poured into the gap between the outer wall of the anti-collapse casing 6 and the mouth of the drilling hole 3). At the same time, the anti-collapse casing 6 is fixed at the mouth of the drilling hole 3, allowing the drill pipe 2 to pass through the anti-collapse casing 6 for operation. By installing and fixing the anti-collapse casing 6, excessive power can be prevented from causing a large amount of debris in the shallow hole wall, thereby preventing the shallow hole wall from collapsing during subsequent deeper drilling. It can also prevent rock fragments from falling into the hole and blocking the drill pipe 2.

[0017] S3: If Figure 1 As shown, the down-the-hole hammer 1 continues to drill downward until the drilling of the guide hole 3 is completed. During this process, intermittent air blowing is used to clean the rock chips 15 at the bottom of the guide hole 3, so that the rock chips 15 are discharged from the chip discharge hole 8, and water is continuously injected into the guide hole 3 through the water injection pipe 9 to control dust.

[0018] In this embodiment, as excavation progresses, the drill rod 2 needs to be lengthened to accommodate the needs of the down-the-hole hammer 1. Intermittent air blowing is performed using an air compressor, causing rock chips 15 to be discharged from the chip discharge hole 8 and collected in the rock chip collection pit 5. The down-the-hole hammer 1 easily generates a large amount of dust during operation, which significantly pollutes the environment. This is achieved by continuously injecting water through the water injection pipe 9. The diameter of the water injection pipe 9 is 1 cm, which should not be too large to prevent excessive water flow from causing the water level at the bottom of the hole to deepen, thereby preventing the down-the-hole hammer 1 from being completely submerged in water and reducing work efficiency.

[0019] S4: Recover the anti-collapse device and the down-the-hole hammer 1, and install the diagonal support pipe 4 in the guide hole 3.

[0020] In this embodiment, a manipulator is used to insert the diagonal support tube 4 into the wall of the lead hole 3. When the diagonal support tube 4 is inserted to the bottom, it should be vibrated and pressured in time periods and multiple times to ensure that the bottom of the diagonal support tube 4 is in effective contact with the rock layer 14. The bottom of the diagonal support tube 4 is sealed with a bottom steel plate 10. Grouting holes 11 are provided on the bottom side wall of the diagonal support tube 4 and the bottom steel plate 10. The grouting holes 11 on the diagonal support tube 4 are blocked with anti-blocking foam to prevent loose gravel on the wall of the lead hole 3 from blocking it. During grouting, the slurry will squeeze the anti-blocking foam, causing the slurry to flow out of the diagonal support tube 4. Specifically, when the down-the-hole hammer 1 is used to excavate the lead hole 3, the wall of the lead hole 3 will be uneven. The grouting holes 11 of the diagonal support tube 4 are only provided with anti-blocking foam, and no barbs are provided. This avoids the problem that the diagonal support tube 4 cannot be placed smoothly due to being stuck on the irregular hole wall. The bottom of the diagonal bracing tube 4 is not provided with a pile tip. Instead, the bottom of the diagonal bracing tube 4 is sealed with a bottom sealing steel plate 10 , and grouting holes 11 are provided on the bottom sealing steel plate 10 to solve the problem of damage to the pile tip caused by concentrated force on the pile tip.

[0021] S5: If Figure 2 As shown, the grouting pipe 9 is installed in the diagonal support pipe 4 and fills the gaps between the diagonal support pipe 4 and the grouting pipe 9 and between the diagonal support pipe 4 and the lead hole 3 .

[0022] In this embodiment, rock chips are used to fill the gaps between the diagonal support pipe 4 and the grouting pipe 9 and between the diagonal support pipe 4 and the lead hole 3. The rock chips 15 are used for filling, which can reduce the use of other backfill materials.

[0023] S6: Grouting is performed using the grouting pipe 9 to effectively fill and bond the gaps between the diagonal bracing pipe 4 and the surrounding bedrock.

[0024] In this embodiment, during the grouting process, the slurry first flows into the rock debris 15 between the diagonal support tube 4 and the grouting tube 9, then flows through the grouting holes 11 in the diagonal support tube 4 and the bottom steel plate 10 into the rock debris 15 between the diagonal support tube 4 and the lead hole 3, and finally flows into the gap in the rock layer 14. During grouting, the slurry is ensured to flow from the outer wall of the diagonal support tube 4 along the wall of the lead hole 3 to the orifice of the lead hole 3 to ensure the density of the grouting.

[0025] The beneficial technical effects of this embodiment are: effectively solving the problem of drilling holes for diagonal bracing construction where there is bedrock above the bottom of the foundation pit, and further solving the problem of being unable to sink piles when there is bedrock above the bottom of the foundation pit during diagonal bracing construction (it is impossible to sink piles to the designed depth by static pressure or conventional drilling methods), improving the scope of application of diagonal bracing (it can be used when there is bedrock above the bottom of the foundation pit), solving the problem that cantilever support structures cannot be used due to high requirements for surrounding environmental protection and horizontal supports cannot be used, having little impact on the surrounding environment, being environmentally friendly, and having significant overall effects.

[0026] Although the above embodiments have described in detail the concepts and embodiments of the present invention with reference to the accompanying drawings, ordinary technicians in this field can recognize that various improvements and modifications can still be made to the present invention without departing from the scope of the claims, so they are not described in detail here.

Claims

1. A drilling method suitable for diagonal bracing construction where bedrock exists above the bottom of a foundation pit, characterized in that The method comprises: S1: Using a down-the-hole hammer of a down-the-hole drill, a pilot hole is drilled obliquely downward at the location where the diagonal support pipe is set in the rock formation; S2: After the down-the-hole hammer drill has excavated to a certain depth in the rock formation, an anti-collapse device is installed and fixed at the opening of the pilot hole, and a water injection pipe is set in the pilot hole; The anti-collapse device is provided with a chip removal hole on one side thereof close to the retaining pile, one end of the water injection pipe is located in the introduction hole, and the other end passes through the chip removal hole and extends to the outside of the anti-collapse device; S3: The down-the-hole hammer continues to drill downward until the pilot hole is drilled. During this process, intermittent air blowing is used to clean the rock debris at the bottom of the pilot hole so that the rock debris is discharged from the chip removal hole. Water is continuously injected into the pilot hole through the water injection pipe to control dust. S4: Recovering the anti-collapse device and the down-the-hole hammer, and installing the diagonal support pipe in the guide hole; S5: installing a grouting pipe in the diagonal bracing pipe and filling the gap between the diagonal bracing pipe and the grouting pipe and between the diagonal bracing pipe and the lead hole; S6: Utilize the grouting pipe to perform grouting operation.

2. A drilling method suitable for diagonal bracing construction in which bedrock exists above the bottom of a foundation pit as claimed in claim 1, characterized in that In step S1, before drilling the guide hole, the shallow soil layer, residual soil and fully weathered rock or broken and diggable strongly weathered rock are removed, the site is leveled, and a rock chip collection pit is excavated near the position where the diagonal support pipe is set in the rock layer. The rock chip collection pit is set close to the retaining pile.

3. A hole-guiding method suitable for diagonal bracing construction in which bedrock exists above the bottom of a foundation pit as claimed in claim 2, characterized in that In step S2, the installation and fixing method of the anti-collapse device is as follows: The anti-collapse casing of the anti-collapse device is installed at the orifice of the guide hole, and a sealing plate is set on the top of the anti-collapse casing, wherein the sealing plate is provided with a through hole allowing the drill rod of the down-the-hole drill to pass through; concrete is poured at the orifice of the guide hole to fix the anti-collapse casing at the orifice of the guide hole.

4. A drilling method suitable for diagonal bracing construction in a foundation pit with bedrock above the bottom of the foundation pit as claimed in claim 3, characterized in that In step S3, an air compressor is used to perform intermittent air blowing, so that the rock chips are discharged from the chip discharge hole and collected through the rock chip collection pit.

5. A drilling method suitable for diagonal bracing construction in a foundation pit with bedrock above the bottom of the foundation pit as claimed in claim 4, characterized in that In step S4, a robot is used to insert the diagonal bracing tube into the wall of the guide hole. When the diagonal bracing tube is inserted to the bottom, vibration pressure is applied in time periods and multiple times. The bottom end of the diagonal bracing tube is sealed by a bottom sealing steel plate. Grouting holes are provided on the diagonal bracing tube and the bottom sealing steel plate, and the grouting holes of the diagonal bracing tube are sealed by anti-blocking foam.

6. A hole-guiding method suitable for diagonal bracing construction in a foundation pit with bedrock above the bottom of the foundation pit as claimed in claim 5, characterized in that In step S5, rock cuttings are used to fill the gaps between the diagonal bracing pipe and the grouting pipe and between the diagonal bracing pipe and the lead hole.

7. A hole-guiding method suitable for diagonal bracing construction in a foundation pit with bedrock above the bottom of the foundation pit as claimed in claim 6, characterized in that In step S6, during grouting, ensure that the slurry flows from the outer wall of the diagonal support pipe along the hole wall of the lead hole to the hole mouth of the lead hole.

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