CN116716879A - An underwater double-casing cast-in-place pile construction method suitable for hard rock seabed - Google Patents

Abstract

The invention discloses a construction method for underwater double-casing cast-in-place piles suitable for seabeds with hard rock layers. It belongs to the technical field of cast-in-place piles and includes the following steps: S1. Hang the outer casing, and use a punching pile driver to drill out the cast-in-place piles. Allow the outer casing to naturally sink to the outer casing hole on the hard rock layer, expand the outer casing hole, and support and seal the outer casing in the expanded hole; S2. Hoist the inner casing to the outer casing hole. In the barrel, a punching pile driver is used to drill an inner casing hole with a depth of 0.5m~1m, and the inner casing is supported and blocked; S3. A down-the-hole drill is used to drill the anchor hole and lower the anchor rod. ;S4. Pour concrete mortar into the inner casing. After the concrete mortar reaches the preset strength, withdraw the support between the inner casing and the outer casing, and pour concrete mortar between the inner casing and the outer casing. . While avoiding "undercut" and "burst" caused by the pile hammer of the punching pile driver, anchor rods are used to ensure the load-bearing capacity and stability of the pile foundation, speed up the construction progress, and greatly reduce the cost of hole formation.

Description

A construction method for underwater double-cased cast-in-place piles suitable for seabeds with hard rock layers

Technical field

The present invention relates to the technical field of cast-in-place piles, and in particular to a construction method of underwater double-casing cast-in-place piles suitable for seabeds with hard rock layers.

Background technique

During the construction of underwater double-casing cast-in-place piles in complex sea areas, punching pile drivers are often used to drill pile holes, and internal and external steel casings with different burial depths are arranged, and then concrete is poured into the pile holes to Predetermined height, after the concrete solidifies, a double-casing cast-in-place pile is formed. The double-casing cast-in-place pile can overcome the problems of steel casing bottom opening curling and drum bottom opening leakage that often occur when steel casings are buried on high-strength bare rock or inclined rock seabed. Problems such as slurry and casing slippage. However, due to the particularity and complexity of complex sea areas, there are complex covering layers in the underwater bedrock. The upper covering layer is mostly loose accumulations or sediments such as silt, and the lower covering layer is mostly hard rock. For example, the patent number is "201910087227.7 ", the disclosed "Construction Technology of Double Casing Casings for Grouted Piles" discloses the use of a pile hammer to continue drilling through the mortar layer until a hole is drilled in the hard rock layer. When a percussion drill drills into a hard rock layer, because the hard rock is relatively hard, it is easy to cause damage to the drill bit as the drilling goes deeper, which will seriously extend the construction period and increase time and economic costs.

Contents of the invention

The purpose of the present invention is to solve the above technical problems and provide a construction method of underwater double-casing cast-in-place piles suitable for seabeds with hard rock layers. On the basis of the traditional punching pile driver drilling construction, the down-the-hole drilling construction is introduced. process to avoid "undercutting" and "blasting hammer" caused by the pile hammer of the punching pile driver. At the same time, anchor rods are used to ensure the load-bearing capacity and stability of the pile foundation, speeding up the construction progress and greatly reducing the cost of hole formation. .

In order to achieve the above object, the present invention provides the following solution: The present invention discloses a construction method of underwater double casing cast-in-place piles suitable for seabeds with hard rock layers, which includes the following steps:

S1. Lift the outer casing vertically to the piling area of the seabed, and use a punching pile driver to drill an outer casing for the outer casing to naturally sink to the hard rock layer in the piling area. Barrel hole, the outer casing hole is expanded, and the bottom end of the outer casing is supported and blocked in the expanded hole;

S2. Lift the inner casing vertically into the outer casing, and use the punching pile driver to drill the hard rock layer at the bottom of the inner casing to create an inner protection for the inner casing to sink naturally. Barrel hole, the depth of the inner casing hole is 0.5m~1m, and the bottom end of the inner casing is supported and blocked from between the inner casing and the outer casing;

S3. Use down-the-hole drilling to drill anchor holes on the hard rock layer in the inner casing and between the inner casing and the outer casing and lower the anchor rod;

S4. Pour concrete mortar into the inner casing. After the concrete mortar reaches the preset strength, withdraw the support between the inner casing and the outer casing, and add water to the inner casing and the outer casing. Concrete mortar is poured between the outer casings.

Preferably, in step S1, step S2 and step S3, air compressor air supply is used to promptly clean the drilling slag in the outer casing hole, the inner casing hole and the anchor hole.

Preferably, in step S1, the diver goes into the water, finds out the surrounding conditions of the outer casing, and manually expands and cleans the outer casing hole.

Preferably, in steps S1 and S2, stacking sand bags are used for support and sealing.

Preferably, in step S3, four anchor holes are evenly arranged in the circumferential direction of the hard rock layer between the inner casing and the outer casing, and eight anchor holes are drilled in the inner casing. The anchor holes are in one group with each other, and multiple groups of the anchor holes are arranged circumferentially.

Preferably, a steel cage is used to detect the verticality and hole diameter of the anchor hole, and a measuring rope is used to measure the depth of the anchor hole and the thickness of the sediment at the bottom of the hole.

Preferably, step S1 also includes step S0, which is to set up a steel platform, set a cross control net and a reference point on the steel platform, mark the hole positions corresponding to the pile forming area, and then perform the above-mentioned step on the steel platform. The holes are cut to form holes for lowering the steel casing, and the casing positioning frame is installed on the steel platform.

Preferably, the distance between the outer casing and the inner casing is 0.3~0.5m.

Preferably, the coaxiality deviation between the outer casing and the inner casing is not greater than 0.05m.

Preferably, the depth of the anchor hole is 0.5~1.0m, and the diameter is 0.1m~0.12m.

Compared with the prior art, the present invention achieves the following technical effects:

This invention is based on the drilling construction of the traditional punching pile driver, and adopts the down-the-hole drilling construction technology. The punching pile driver only needs to drill a 0.5m~1m shallow hole in the hard rock layer, and will not cause any damage to the punching pile driver. Causes phenomena such as "undercut" and "blasting hammer". The remaining anchor holes are drilled by down-the-hole drills and the anchor rods are lowered to ensure the load-bearing capacity and stability of the pile foundation. This speeds up the construction progress and greatly reduces the cost. hole cost.

Description of the drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the drawings needed to be used in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some of the drawings of the present invention. Embodiments, for those of ordinary skill in the art, other drawings can also be obtained based on these drawings without exerting creative efforts.

Figure 1 is a structural perspective view of an underwater double-casing cast-in-place pile;

Figure 2 is a top structural view of the underwater double-casing cast-in-place pile.

Explanation of reference signs: 1. Outer casing; 2. Inner casing; 3. Anchor rod; 4. Concrete pile body; 5. Sea level; 6. Sand layer; 7. Clay layer; 8. Crushed rock layer; 9 , Gravel layer; 10. Hard rock layer; 11. Concrete core; 12. Sand bag.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

This embodiment provides an underwater double-casing cast-in-place pile construction method suitable for seabeds with hard rock layers. As shown in Figures 1 to 2, it includes the following steps:

S1. Lift the outer casing 1 vertically to the piling area of the seabed, then extend the pile hammer of the punching pile driver vertically into the outer casing 1, and drill the outer casing hole in the piling area. The outer casing hole is drilled from the surface of the seabed to the top of the hard rock layer 10. After the outer casing hole is formed, the outer casing 1 can naturally fall into the outer casing hole due to its own gravity, and the outer casing hole is expanded. The bottom end of the outer casing 1 is supported and blocked in the hole; the surface layer of the seabed is usually sand layer 6, clay layer 7, crushed rock layer 8, gravel layer 9, and hard rock layer 10 from top to bottom. Of course, it is also possible There are only clay layer 7, crushed rock layer 8, gravel layer 9, and hard rock layer 10. However, regardless of the seed composition, the outer casing hole only needs to be drilled from top to bottom to the upper surface of the hard rock layer 10;

S2. Lift the inner casing 2 vertically into the outer casing 1. After the pile hammer is replaced by the punching pile driver, the pile hammer extends into the inner casing 2 and drills out the hard rock layer 10 at the bottom of the inner casing 2. The depth of the inner casing hole is 0.5m~1m. When the hole is formed, the inner casing 2 sinks into the inner casing hole due to its own gravity. The depth of the inner casing hole will not cause the pile punching pile driver to If the hammer is damaged, support and seal the bottom end of the inner casing 2 from between the inner casing 2 and the outer casing 1;

S3. Use down-the-hole drilling to drill the anchor hole in the hard rock layer inside the inner casing 2 and between the inner casing 2 and the outer casing 1 and lower the anchor rod 3;

S4. Pour concrete mortar into the inner casing 2. The concrete mortar will seep down into the anchor hole of the inner casing 2. After the concrete mortar reaches the preset strength, withdraw between the inner casing 2 and the outer casing 1. For support, pour concrete mortar between the inner casing 2 and the outer casing 1. The concrete mortar will penetrate into the anchor hole between the inner casing 2 and the outer casing 1. The concrete mortar between the casing 2 and the outer casing 1 will form the concrete pile body 4, the concrete mortar in the anchor hole will form the concrete core 11, and the anchor 3 can effectively ensure the connection between the double casing cast-in-place pile and the hard rock layer 10 stability.

In this embodiment, as shown in Figures 1 to 2, in steps S1, S2 and S3, the air compressor air supply method is used to promptly clean the drilling slag in the outer casing hole, the inner casing hole and the anchor hole.

Specifically: in step S1, the punching pile driver is in place, the pile hammer of the punching pile driver extends into the outer casing 1 to impact the seabed, a small amount of mud is added during the impact process, and drilling stops when the pile hammer reaches the hard rock layer 10 Then, the outer casing hole is formed, and the air compressor is used to add compressed air to the water in the outer casing hole. The pressure generated can eject the slag sample from the outer casing port 1, and the punching pile driver can be removed.

In step S2, after the punching pile driver is replaced with a new pile hammer, the punching pile driver is in position again, and the pile hammer extends into the inner casing 2 to impact the hard rock layer 10 to form an inner casing hole, and the air compressor is used to protect the inner casing. When compressed air is added to the water in the cylinder hole, the pressure generated can eject the slag sample from the inner casing 2, and the punching pile driver can be removed.

In step S3, in order to ensure the grouting effect, an air compressor is used to clean the holes twice to ensure the grouting quality in step S4.

In this embodiment, as shown in Figures 1 to 2, in step S1, the diver goes into the water, finds out the surrounding conditions of the outer casing 1, and manually expands and cleans the outer casing hole.

Furthermore, in this embodiment, as shown in Figures 1 to 2, in steps S1 and S2, the method of stacking sand bags 12 is used for support and sealing. In specific step S1, high sandbags 12 are piled (or thrown) around the bottom end of the outer casing 1. The sandbags 12 are stacked tightly and fill the outer casing holes to achieve the effect of plugging leaks and fixing the outer casing 1. In step S2, the throwing method is used to throw sandbags 12 between the outer casing 1 and the inner casing 2. The sandbags 12 are stacked tightly to achieve the effect of blocking leakage and fixing the inner casing 2.

In this embodiment, as shown in Figures 1 to 2, in step S3, four anchor holes are evenly arranged in the circumferential direction of the hard rock layer 10 between the inner casing 2 and the outer casing 1, and the inner casing 2 is drilled Eight anchor holes are provided, two anchor holes form a group with each other, and multiple groups of anchor holes are arranged circumferentially.

In this embodiment, as shown in Figures 1 to 2, a steel cage is used to detect the verticality and hole diameter of the anchor hole, and a measuring rope is used to measure the depth of the anchor hole and the thickness of the sediment at the bottom of the hole.

In this embodiment, as shown in Figures 1 to 2, step S1 also includes step S0 construction preparation: setting up a steel platform, setting a cross control network and reference points on the steel platform, and marking the pile corresponding to the pile area. hole position, and then cut the hole position on the steel platform to form a hole for lowering the steel casing. Install the casing positioning frame on the steel platform. After adjusting the positioning frame, the outer casing 1 can be lowered. Make preparations before construction and strictly follow relevant specifications and operating procedures to ensure the safety and quality of the construction process.

In this embodiment, as shown in Figures 1 to 2, the distance between the outer casing 1 and the inner casing 2 needs to be guaranteed to be 0.3~0.5m. The lengths of the outer casing 1 and the inner casing 2 need to be set in actual engineering, but it is necessary to ensure that the tops of the outer casing 1 sinking into the outer casing hole and the tops of the inner casing 2 sinking into the inner casing hole are evenly spaced. Located 5 above sea level. The length difference between the outer casing 1 and the inner casing 2 is usually between 0.5m~1m, so that after the inner casing 2 sinks into the inner casing hole, the top of the outer casing 1 and the inner casing 2 The surfaces are flush. When pouring concrete mortar, it needs to be poured to the top surface of the inner casing 2. The outer casing 1 and the inner casing 2 are generally made of steel casings.

The concrete must be poured quickly and in one go. During the first pouring, the first buried depth of the conduit should be greater than 1.0m. As the perfusion continues, the tube can be extubated at any time, and the pause time should not exceed 30 minutes. During the entire pouring process, the buried depth of the conduit in the concrete is preferably 2.0m-6.0m, which cannot be less than 2m or greater than 6m. A dedicated person must be assigned to measure the buried depth of the conduit and the height difference between the inner and outer concrete surfaces of the inner casing 2. Fill in the underwater concrete pouring records in a timely manner.

Furthermore, in this embodiment, as shown in Figures 1 to 2, the coaxiality deviation between the outer casing 1 and the inner casing 2 is not greater than 0.05m. The deviation of the inclination of the inner casing 2 should not be greater than 1%, and the finally lowered inner casing 2 meets the horizontal position and verticality requirements.

In this embodiment, the depth of the anchor hole is 0.5~1.0m, and the diameter is 0.1m~0.12m. When drilling, fix the down-the-hole drill, turn on the down-the-hole drilling rig, and adjust the drilling angle of the drill rig according to the terrain and geological conditions before drilling. It is necessary to control after drilling to avoid secondary alignment drilling and meet the requirements of the pilot hole. After the anchor hole reaches the design elevation, check the hole position, hole diameter, hole depth, hole shape, and geological conditions at the bottom of the hole. The hole position deviation shall not be greater than 0.05m, and the inclination shall not be greater than 5‰.

Specific examples are used in the present invention to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea; at the same time, for those of ordinary skill in the art, based on this The idea of the invention will be subject to change in the specific implementation and scope of application. In summary, the contents of this description should not be construed as limitations of the present invention.

Claims (10)

1. An underwater double-casing cast-in-place pile construction method suitable for hard rock seabeds, which is characterized by including the following steps: S1. Lift the outer casing vertically to the piling area of the seabed, and use a punching pile driver to drill an outer casing for the outer casing to naturally sink to the hard rock layer in the piling area. Barrel hole, the outer casing hole is expanded, and the bottom end of the outer casing is supported and blocked in the expanded hole; S2. Lift the inner casing vertically into the outer casing, and use the punching pile driver to drill the hard rock layer at the bottom of the inner casing to create an inner protection for the inner casing to sink naturally. Barrel hole, the depth of the inner casing hole is 0.5m~1m, and the bottom end of the inner casing is supported and blocked from between the inner casing and the outer casing; S3. Use down-the-hole drilling to drill anchor holes on the hard rock layer in the inner casing and between the inner casing and the outer casing and lower the anchor rod; S4. Pour concrete mortar into the inner casing. After the concrete mortar reaches the preset strength, withdraw the support between the inner casing and the outer casing, and add water to the inner casing and the outer casing. Concrete mortar is poured between the outer casings. 2. A construction method for underwater double-cased cast-in-place piles suitable for seabeds with hard rock layers according to claim 1, characterized in that in step S1, step S2 and step S3, an air compressor is used to supply air in a timely manner. Clean the drilling slag in the outer casing hole, the inner casing hole and the anchor hole. 3. A construction method for underwater double-casing cast-in-place piles suitable for seabeds with hard rock layers according to claim 1, characterized in that, in step S1, divers go into the water to find out the surrounding conditions of the outer casing, The outer casing hole is manually expanded and cleaned. 4. A construction method for underwater double-cased cast-in-place piles suitable for seabeds with hard rock layers according to claim 3, characterized in that, in steps S1 and S2, the method of stacking sand bags is used for support and sealing. . 5. A construction method for underwater double-casing cast-in-place piles suitable for seabeds with hard rock layers according to claim 1, characterized in that in step S3, there is a gap between the inner casing and the outer casing. Four anchor holes are evenly arranged in the circumferential direction of the hard rock layer, and eight anchor holes are drilled in the inner casing. Two of the anchor holes form a group with each other, and multiple groups of anchor holes are arranged circumferentially. cloth. 6. A construction method for underwater double-cased cast-in-place piles suitable for seabeds with hard rock layers according to claim 5, characterized in that a steel bar detection cage is used to detect the verticality and aperture of the anchor hole. The measuring rope measures the depth of the anchor hole and the thickness of the sediment at the bottom of the hole. 7. A construction method for underwater double-cased cast-in-place piles suitable for seabeds with hard rock layers according to claim 1, characterized in that step S1 also includes step S0 before step S1, erecting a steel platform and setting it on the steel platform. Use the cross control network and reference points to mark the hole positions corresponding to the pile forming area, then cut the holes on the steel platform to form the steel casing lowering hole, and install the casing positioning frame on the steel platform. . 8. A kind of underwater double casing cast-in-place pile construction method suitable for seabed with hard rock layer according to claim 5, characterized in that the distance between the outer casing and the inner casing is 0.3~ 0.5m. 9. A construction method for underwater double-casing cast-in-place piles suitable for seabeds with hard rock layers according to claim 8, characterized in that the coaxiality between the outer casing and the inner casing is The deviation is not greater than 0.05m. 10. A construction method for underwater double-cased cast-in-place piles suitable for seabeds with hard rock layers according to claim 9, characterized in that the depth of the anchor hole is 0.5~1.0m and the diameter is 0.1m. ~0.12m.