Rotary digging hole-forming cast-in-place pile rich in large-diameter loose sandy cobble stratum and construction method

Abstract

The invention relates to a rotary excavating hole-forming cast-in-place pile for a stratum rich in large-diameter loose sandy cobbles and a construction method, and aims at solving the problem of easy hole collapse by adopting a high-pressure rotary jet grouting consolidating and hardening cobble layer structure for the stratum rich in large-diameter loose sandy cobbles, ensuring the safety and stability of surrounding buildings and the pile-forming quality and saving the cost. The drilling construction of a pile hole is carried out by adopting a small drill bit hole guiding-cutting tooth drill bit hole expanding combined hole forming technology, so that the drilling efficiency is improved, and the abrasion degree of the drill bit is reduced; the pebble stratum rotary drilling self-propelled steel casing hole-forming system and the efficient steel casing embedding and pulling-out system are adopted for steel casing construction, mechanical input is reduced, the steel casing can be recycled, the first section of casing and the standard section of casing are connected through the casing connecting end and the connecting and fixing hole, welding operation is avoided, the environment is protected, and the construction efficiency is improved. The construction efficiency and accuracy of the steel casing are improved, and the cost and the construction period are saved.

Description

Technical Field

[0001] The invention belongs to the field of foundation and basic engineering, and in particular relates to a cast-in-place pile bored by rotary drilling in a stratum rich in large-diameter loose sand and gravel, and a construction method thereof. Background Art

[0002] With the continuous expansion of urban construction and reconstruction, rotary bored piles have become an important support for ensuring the safety of pile foundation construction. They are widely used due to their advantages such as fast construction speed, high construction safety factor, and reliable pile quality. When constructing pile foundations for bridge projects in water-crossing sections, it is often necessary to cross gravel strata. However, due to their loose structure and high permeability, gravel strata are prone to collapse and leakage, which poses great difficulties for pile foundation construction. When encountering gravel strata rich in large-diameter blocks during rotary drilling operations, how to avoid large-scale collapse, how to improve drilling construction efficiency, and how to avoid the flow of concrete into adjacent piles during the pouring of pile core concrete to form inclined hardened concrete that makes it difficult to drill, have become problems in rotary bored pile drilling in gravel strata rich in large-diameter pebbles.

[0003] In view of this, in view of the shortcomings in the previous construction of cast-in-place piles in sand and gravel strata, a new type of rotary-drilled cast-in-place pile and construction method for loose sand and gravel strata rich in large blocks is urgently needed to improve construction efficiency, improve construction quality, and ensure the safety and reliability of the construction process. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a cast-in-place pile bored by rotary drilling in a stratum rich in loose sand and gravel with large block diameters and a construction method.

[0005] The construction method of the rotary-drilled bored pile in a stratum rich in large-diameter loose sand and gravel comprises the following steps: Step 1: Drill grouting holes around the pile hole, and inject grout into the grouting holes to obtain a solidified area; Step 2: Steel casing construction: Set up a guide frame for efficient steel casing burial and removal, carry out steel casing burial construction, and complete the burial of steel casing through a self-propelled steel casing hole-forming system with rotary drilling in pebble strata; Step 3: Construction of steel cage: After drilling and cleaning the hole, tie the steel cage according to the pile hole diameter requirements, and then use a truck crane to lower the steel cage; Step 4: pouring concrete and testing: pouring concrete into the pile hole to form a cast-in-place pile; Step 5: Karst cavity treatment construction: Set up a lava cavity filling system, set up grouting pipes next to the bored piles, and perform grouting construction to fill the karst cavity with slurry.

[0006] Preferably, in step 2, the steel casing efficient burial and removal system includes a pad, soil nails, a vertical frame, a horizontal frame and reinforcing diagonal braces. The pad is fixed to both sides of the steel casing by soil nails, the vertical frame is arranged on the pad, the horizontal frame connects the vertical frames on both sides, and the reinforcing diagonal braces are fixed at the intersection of the horizontal frame and the vertical frame.

[0007] Preferably, in step 2, the self-propelled steel casing drilling system for rotary drilling in pebble formation includes a rotary drilling rig and a drill rod, the rotary drilling rig is arranged on the ground, the drill rod is arranged on the rotary drilling rig, and a drill rig driver and a drill bit are arranged at the bottom of the drill rod; the steel casing is obtained by splicing a first-section casing and a standard-section casing, a casing driver is arranged at the top of the standard-section casing, the casing driver is fixed to the drill rig driver with fixing bolts through a driving connecting plate, connecting fixing holes are arranged at the top of the first-section casing and the upper and lower ends of the standard-section casing, casing connecting ends are arranged at the top of the first-section casing and the upper end of the standard-section casing, and cutting teeth are arranged at the bottom of the first-section casing.

[0008] Preferably, in step three, a combined hole-forming technology of small drill bit hole-leading and pick drill bit hole-expanding is used during drilling, a rotary drill is used for drilling, a small drill bit is used for hole-leading, and then a pick drill bit with the same hole diameter as the pile hole is used for hole-expanding to complete the drilling construction; after the drilling is completed, a hole-forming detector is used to check the hole depth, hole shape, hole diameter and verticality and clean the hole.

[0009] Preferably, in step three, after the steel cage is lowered, the guide tube construction and secondary hole cleaning construction are carried out. The guide tube is installed by crane in cooperation with manual work. The guide tube is first placed to the bottom of the pile hole by the crane, and then lifted for a distance. After the height of the guide tube is determined, the height of the guide tube chuck is adjusted with an I-beam, and the guide tube is clamped with the chuck; air lift reverse circulation is used for secondary hole cleaning construction.

[0010] Preferably, in step three, the lava cavity filling system includes a grouting pipe and a guide hole pipe. There is a karst cavity around the bored pile. The guide hole pipe is arranged next to the bored pile and extends into the karst cavity. The grouting pipe is arranged in the guide hole pipe. During grouting construction, slurry is poured into the karst cavity through the grouting pipe.

[0011] Preferably, the area outside the solidification zone and below the ground line is a high-pressure jet-jet-consolidated hardened pebble layer structure; below the ground line are a fill layer, a clay layer, a pebble layer and a mudstone layer in sequence.

[0012] The invention relates to a cast-in-place pile bored by rotary drilling in a stratum rich in loose sand and gravel with large block diameters, which is obtained by any of the above-mentioned methods.

[0013] The beneficial effects of the present invention are: 1) The present invention adopts high-pressure rotary spraying to consolidate and harden the pebble layer structure for the stratum rich in large-diameter loose sand and pebbles, which solves the problem of easy hole collapse, ensures the safety and stability of surrounding buildings and the quality of pile formation, and saves costs.

[0014] 2) The present invention adopts a small drill bit hole-cutting drill bit hole-expanding combined hole-forming technology to carry out pile hole drilling construction, thereby improving drilling efficiency and reducing drill bit wear.

[0015] 3) The present invention adopts a self-propelled steel casing hole-forming system for rotary drilling in pebble strata and a steel casing efficient burying and removal system to construct steel casing, which reduces the mechanical input, and the steel casing can be recycled. The first section of the casing and the standard section of the casing are connected by the casing connecting end and the connecting fixing hole, without welding operation, which protects the environment, improves the efficiency and accuracy of the steel casing construction, and saves costs and construction period.

[0016] 4) The present invention adopts a lava cavity filling system to fill the karst cavity in the formation, which has fast construction speed, simple operation and good filling effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the structure of the pebble layer consolidated and hardened by high-pressure jet spraying; Figure 2 It is a top view of the structure of the pebble layer consolidated and hardened by high-pressure jet spraying; Figure 3 It is a schematic diagram of the system structure of a self-propelled steel casing hole-forming rotary drill in pebble formation; Figure 4 yes Figure 3 Schematic diagram of the connection structure of the middle first section casing; Figure 5 yes Figure 3 Schematic diagram of the connection structure of the medium standard section casing; Figure 6 This is a front view of the system structure for efficient burial and removal of steel casing; Figure 7 It is a side view of the system structure for efficient burial and removal of steel casing; Figure 8 is a schematic diagram of the lava cavity filling architecture.

[0018] Explanation of the accompanying drawings: 1-ground line, 2-fill layer, 3-clay layer, 4-pebble layer, 5-mudstone layer, 6-grouting hole, 7-pile hole, 8-solidification area, 9-rotary drilling rig, 10-drill rod, 11-drill rig driver, 12-fixing bolt, 13-drive connecting plate, 14-drill bit, 15-casing driver, 16-standard section casing, 17-casing connection end, 18-first section casing, 19-cutting tooth, 20-connection fixing hole, 21-steel casing, 22-pad, 23-soil nail, 24-vertical frame, 25-horizontal frame, 26-reinforced diagonal brace, 27-cast-in-place pile, 28-karst cavity, 29-grouting pipe, 30-hole guide pipe, 31-slurry. DETAILED DESCRIPTION

[0019] The present invention is further described below in conjunction with embodiments. The description of the following embodiments is only used to help understand the present invention. It should be noted that for ordinary persons in the art, without departing from the principle of the present invention, the present invention can also be modified in some ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0020] Embodiment 1 As an embodiment, the rotary bored cast-in-place pile in a loose sandy gravel formation rich in large blocks includes a high-pressure rotary jet consolidation and hardening gravel layer structure, a gravel formation rotary drilling self-propelled steel casing hole forming system, a steel casing efficient burying and removal system and a lava cavity filling system; like Figure 1 and Figure 2 As shown, the high-pressure rotary spraying consolidation hardened pebble layer structure includes a ground line 1, a fill layer 2, a clay layer 3, a pebble layer 4, a mudstone layer 5, a grouting hole 6, a pile hole 7, and a solidification area 8. Below the ground line 1 are the fill layer 2, the clay layer 3, the pebble layer 4, and the mudstone layer 5 in sequence. The grouting holes 6 are arranged around the pile holes 7, and the solidification area 8 is the area formed after the grouting holes 6 are grouted. A solidification zone 8 is formed around the pile hole 7, and a high-pressure rotary spraying consolidation and hardening pebble layer structure is formed from top to bottom outside the solidification zone 8; The steel casing 21 of the cast-in-place pile 27 is obtained by splicing the first casing 18 and the standard casing 16. The self-propelled steel casing hole-forming system for rotary drilling in pebble formations includes a rotary drilling rig 9 and a drill rod 10. The bottom end of the drill rod 10 is connected to the casing driver 15 at the top of the standard casing 16. like Figure 6 and Figure 8 As shown, the steel casing efficient burial and removal system is arranged on the ground around the steel casing 21; there is a karst cavity 28 around the cast-in-place pile 27, and the grouting pipe 29 in the lava cavity filling system is arranged next to the cast-in-place pile 27 for injecting slurry 31 into the karst cavity 28.

[0021] Embodiment 2 As another embodiment, this embodiment 2 proposes, on the basis of the embodiment 1, a more specific bored cast-in-place pile in a stratum rich in large-diameter loose sand and gravel: like Figure 3As shown, the self-propelled steel casing hole-forming system for rotary drilling in pebble formation includes a rotary drilling rig 9, a drill rod 10, a drill rig driver 11, a fixing bolt 12, a drive connecting plate 13, a drill bit 14, a casing driver 15, a standard section casing 16, a casing connecting end 17, a first section casing 18, a cutting tooth 19, and a connecting and fixing hole 20. The rotary drilling rig 9 is arranged on the ground, the drill rod 2 is arranged on the rotary drilling rig 9, the drill rig driver 11 is arranged on the drill rod 10, the drill bit 14 is arranged on the drill rod 10, the casing driver 15 is arranged on the top of the standard section casing 16, and is fixed to the drill rig driver 11 through the drive connecting plate 13 with fixing bolts, the casing connecting end 17 and the connecting and fixing hole 20 are arranged on the top of the first section casing 18 and the upper and lower ends of the standard section casing 16, and the cutting tooth 19 is arranged at the bottom of the first section casing 18.

[0022] like Figure 6 As shown, the efficient burying and removal system of the steel casing includes a pad 22, soil nails 23, a vertical frame 24, a horizontal frame 25, and a reinforcing diagonal brace 26. The pad 22 is fixed to both sides of the steel casing 21 by the soil nails 23, the vertical frame 24 is arranged on the pad 22, the horizontal frame 25 connects the vertical frames 24 on both sides, and the reinforcing diagonal brace 26 is fixed at the intersection of the horizontal frame 25 and the vertical frame 24.

[0023] like Figure 8 As shown, the lava cavity filling system includes a cast-in-place pile 27, a karst cavity 28, a grouting pipe 29, a borehole pipe 30, and slurry 31. The karst cavity 28 is around the cast-in-place pile 27, the borehole pipe 30 is arranged beside the cast-in-place pile 27 and extends into the karst cavity 28, the grouting pipe 29 is arranged in the borehole pipe 30, and the slurry 31 is arranged in the karst cavity 28.

[0024] It should be noted that the parts in this embodiment that are the same or similar to those in the first embodiment can be referenced to each other and will not be described in detail in this application.

[0025] Embodiment 3 As another embodiment, based on the first and second embodiments, the third embodiment proposes a construction method for bored piles in a stratum rich in loose sand and gravel with large block diameters, including the following steps: Step 1: Drill grouting holes 6 around the pile hole 7, and inject grout into the grouting holes 6 to obtain a solidified area 8; Step 2, steel casing construction: set up a steel casing efficient burying and removal guide frame, carry out steel casing burying construction, and complete the burying of steel casing 21 through the pebble stratum rotary drilling self-propelled steel casing hole forming system; Step 3: Construction of steel cage: After drilling and cleaning the hole, tie the steel cage according to the diameter requirement of the pile hole 7, and then lower the steel cage with a truck crane; Step 4, pouring concrete and testing: pouring concrete into the pile hole 7 to form a cast-in-place pile 27; Step 5, karst cavity treatment construction: set up a lava cavity filling system, set up a grouting pipe 29 next to the cast-in-place pile 27, and perform grouting construction to fill the karst cavity 28 with slurry 31.

[0026] Embodiment 4 As another embodiment, this embodiment 4, based on the embodiment 3, proposes a more specific construction method of bored cast-in-place piles in a stratum rich in loose sand and gravel with large block diameters: Step 1: Construction preparation: Carry out on-site traffic control, close the surrounding area, prepare construction materials and mechanical equipment according to construction requirements, and arrange them to enter the factory one by one.

[0027] Step 2: Pile position layout: Use a total station to layout according to the coordinate values ​​of the pile foundation center and the known control point coordinate values ​​to determine the pile hole position.

[0028] Step three, high-pressure rotary jet grouting construction: After the measurement and positioning are completed, the high-pressure rotary jet drilling rig is moved to the designated pile position, and the high-pressure rotary jet drilling rig is used to drill downward. When the high-pressure rotary jet drilling rig drills to the designed elevation, the drilling is stopped, the grouting machine is in place, and grouting construction is carried out through the grouting hole 6.

[0029] Step 4, steel casing construction: set up the steel casing efficient burying and removal guide frame, the pad 22 is fixed on both sides of the casing 21 by soil nails 23, the vertical frame 24 is set on the pad 22, the horizontal frame 25 connects the vertical frames 24 on both sides, and the reinforcement diagonal brace 26 is fixed at the intersection of the horizontal frame 25 and the vertical frame 24, and the steel casing burying construction is carried out. The rotary drilling rig 9 is set on the ground, the drill rod 2 is set on the rotary drilling rig 9, the drill rig driver 11 is set on the drill rod 10, the drill bit 14 is set on the drill rod 10, the casing driver 15 is set on the top of the standard section casing 16, and is fixed to the drill rig driver 11 with fixing bolts through the drive connecting plate 13. The casing connection end 17 and the connecting fixing hole 20 are set on the top of the first section casing 18 and the upper and lower ends of the standard section casing 16, and the cutting teeth 19 are set at the bottom of the first section casing 18 to complete the burying of the steel casing.

[0030] Step 5: The drilling rig is in place and drilling is started: a rotary drill is used on site to drill the hole, a small drill bit is used to guide the hole, and then a pick drill bit with the same diameter is used to expand the hole to complete the drilling construction.

[0031] Step 6: Hole inspection and hole cleaning: After drilling is completed, use a hole detector to check the hole depth, hole shape, hole diameter and verticality, and clean the hole.

[0032] Step seven, steel cage construction: tie up the steel cage according to the pile hole diameter requirements, and then lower the steel cage with a truck crane.

[0033] Step eight, construction of lower conduit: The conduit is installed by crane and manual labor. First, place the conduit at the bottom of the hole with the crane, and then lift the conduit 40cm. After the height of the conduit is determined, use I-beam to adjust the height of the conduit chuck, and clamp the conduit with the chuck.

[0034] Step nine, secondary hole cleaning construction: use air lift reverse circulation for secondary hole cleaning construction.

[0035] Step 10: Pour concrete and inspect: The pile foundation concrete for the entire line is centrally mixed and processed at a mixing station and transported to the pile positions at the construction site by tank trucks for pouring.

[0036] Step eleven, karst cavity treatment construction: a borehole pipe 30 is arranged beside the cast-in-place pile 27 and extends into the karst cavity 28 , a grouting pipe 29 is arranged in the borehole pipe 30 , and grouting construction is performed, and the slurry 31 fills the karst cavity 28 .

[0037] Step 12: Inspection and acceptance, and removal of construction equipment and machinery.

[0038] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

Claims

1. A construction method for bored piles in a stratum rich in loose sand and gravel with large block diameters, characterized in that: The following steps are involved: Step 1: Drill grouting holes around the pile hole, and inject grout into the grouting holes to obtain a solidified area; Step 2: Steel casing construction: Set up a guide frame for efficient steel casing burial and removal, carry out steel casing burial construction, and complete the burial of steel casing through a self-propelled steel casing hole-forming system with rotary drilling in pebble strata; Step 3: Construction of steel cage: After drilling and cleaning the hole, tie the steel cage according to the pile hole diameter requirements, and then use a truck crane to lower the steel cage; Step 4: pouring concrete and testing: pouring concrete into the pile hole to form a cast-in-place pile; Step 5: Karst cavity treatment construction: Set up a lava cavity filling system, set up grouting pipes next to the bored piles, and perform grouting construction to fill the karst cavity with slurry.

2. The construction method of rotary bored cast-in-place piles in a stratum rich in large-diameter loose sand and gravel according to claim 1 is characterized in that: In step 2, the efficient burial and removal system of the steel casing includes a pad, soil nails, a vertical frame, a horizontal frame and reinforcing diagonal braces. The pad is fixed to both sides of the steel casing by soil nails, the vertical frame is set on the pad, the horizontal frame connects the vertical frames on both sides, and the reinforcing diagonal braces are fixed at the intersection of the horizontal frame and the vertical frame.

3. The construction method of rotary bored cast-in-place piles in a stratum rich in large-diameter loose sand and gravel according to claim 1 is characterized in that: In step 2, the self-propelled steel casing hole-forming system for rotary drilling in pebble formation includes a rotary drilling rig and a drill rod, the rotary drilling rig is arranged on the ground, the drill rod is arranged on the rotary drilling rig, and a drill rig driver and a drill bit are arranged at the bottom of the drill rod; the steel casing is obtained by splicing a first-section casing and a standard-section casing, a casing driver is arranged on the top of the standard-section casing, the casing driver is fixed to the drill rig driver with fixing bolts through a driving connecting plate, connecting fixing holes are arranged on the top of the first-section casing and the upper and lower ends of the standard-section casing, casing connecting ends are arranged on the top of the first-section casing and the upper end of the standard-section casing, and cutting teeth are arranged on the bottom of the first-section casing.

4. The construction method of rotary bored cast-in-place piles in a stratum rich in large-diameter loose sand and gravel according to claim 1 is characterized in that: In step three, a combined hole-making technology of small drill bit hole-leading and pick drill bit hole-expansion is used during drilling. A rotary drill is used for drilling, a small drill bit is used for hole-leading, and a pick drill bit with the same hole diameter as the pile hole is used for hole-expansion to complete the drilling construction. After the drilling is completed, a hole-forming detector is used to check the hole depth, hole shape, hole diameter and verticality and clean the hole.

5. The construction method of rotary bored cast-in-place piles in a stratum rich in large-diameter loose sand and gravel according to claim 1 is characterized in that: In step three, after the steel cage is lowered, the guide tube construction and secondary hole cleaning construction are carried out. The guide tube is installed by crane and manual labor. The guide tube is first placed to the bottom of the pile hole by the crane, and then lifted for a distance. After the height of the guide tube is determined, the height of the guide tube chuck is adjusted with an I-beam, and the guide tube is clamped with the chuck; air lift reverse circulation is used for secondary hole cleaning construction.

6. The construction method of rotary bored cast-in-place piles in a stratum rich in large-diameter loose sand and gravel according to claim 1 is characterized in that: In step three, the lava cavity filling system includes a grouting pipe and a guide hole pipe. There is a karst cavity around the bored pile. The guide hole pipe is arranged next to the bored pile and extends into the karst cavity. The grouting pipe is arranged in the guide hole pipe. During grouting construction, slurry is poured into the karst cavity through the grouting pipe.

7. The construction method of rotary bored cast-in-place piles in a stratum rich in large-diameter loose sand and gravel according to claim 1 is characterized in that: The area outside the solidification zone and below the ground line is a high-pressure jet-jet-consolidated hardened pebble layer structure; below the ground line are a fill layer, a clay layer, a pebble layer and a mudstone layer in sequence.

8. Rotary bored cast-in-place piles in strata rich in large-diameter loose sand and gravel, characterized in that: Obtained by the method according to any one of claims 1 to 7.

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