Underwater anchor rod construction method applied to water-rich pebble stratum

Abstract

The invention relates to the technical field of anchor rod construction, in particular to an underwater anchor rod construction method applied to a water-rich pebble stratum, which comprises the following steps of: 1, constructing a waterproof curtain around a foundation pit; 2, soil is excavated in the foundation pit to the height 0.2 m above the water level in the foundation pit to serve as a construction datum plane, and the water level in the foundation pit is kept equal to the water level outside the foundation pit; 3, an embedded steel sleeve larger than a drilling machine sleeve is embedded at the position H / tan theta away from the waterproof curtain according to the designed inclination angle, the embedded steel sleeve is backfilled and compacted firstly, then cement paste is injected to fix the embedded steel sleeve, H is the vertical distance between the anchor rod and the construction datum plane in the foundation pit, and theta is the inclination angle of the anchor rod inclination angle; water pressure inside and outside the foundation pit can be kept balanced, water gushing and sand gushing can be avoided, the risk caused by the fact that cement paste in the pebble bed is taken away by flowing underground water is made up through secondary grouting, and finally it is guaranteed that the hole is not leaked through the method that cement and water glass double-liquid paste is injected into the hole.

Description

Technical Field

[0001] The invention relates to the technical field of anchor rod construction, in particular to an underwater anchor rod construction method applied to a water-rich pebble stratum. Background Art

[0002] Foundation pit support is a measure to support, reinforce and protect the side walls of the foundation pit and the surrounding environment to ensure the safety of underground structure construction and the surrounding environment of the foundation pit. In the process of foundation pit construction, anchor support reinforcement is often used for reinforcement. At present, when anchor drilling construction is carried out underwater in water-rich pebble strata, water and sand will gush out under the action of water pressure. A large amount of groundwater will gush out of the borehole, carrying a large amount of fine soil particles and sand particles, causing ground settlement around the foundation pit. When cement slurry is injected into the borehole, the cement slurry is lost in large quantities along with the gushing groundwater, resulting in anchor failure, so it needs to be improved. Summary of the invention

[0003] The object of the present invention is to provide an underwater anchor construction method for use in water-rich pebble formations to solve the problems raised in the above-mentioned background technology.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] An underwater anchor construction method applied to a water-rich pebble formation comprises the following steps:

[0006] Step 1: Construct a water-stop curtain around the foundation pit;

[0007] Step 2: Dig soil in the foundation pit to a height of 0.2m above the water level in the foundation pit as the construction reference surface, and keep the water level inside the foundation pit equal to the water level outside the foundation pit;

[0008] Step 3: At a distance of H / tanθ from the water-stop curtain, bury a pre-buried steel casing that is larger than the drilling casing according to the designed inclination angle. First, backfill and compact the pebbles, and then inject cement slurry to fix the pre-buried steel casing. H is the vertical distance between the anchor rod and the construction reference surface in the foundation pit, and θ is the inclination angle of the anchor rod.

[0009] Step 4: Use a hydraulic impact casing drill to drill along the embedded steel casing, penetrate the water-stop curtain when encountering it, and stop the drilling of the drill rod and drill bit of the drill rig until the designed hole depth is reached;

[0010] Step 5: After the hole is formed, clean the sand and rock chips in the hole. After cleaning, pull out the drill rod and drill bit;

[0011] Step 6: Insert anchor rods, grouting pipes, secondary grouting pipes and orifice grouting pipes into the drilling rig casing, then inject cement slurry from the bottom of the hole through the grouting pipes. Pull out the drilling rig casing after the slurry overflows from the orifice;

[0012] Step 7: After the cement slurry solidifies, cement slurry is injected through the secondary grouting pipe for secondary grouting, and then the orifice grouting pipe is opened with clean water pressure;

[0013] Step 8: Dig soil in the foundation pit to 0.5m below the anchor rod as the new construction reference surface, and at the same time lower the water level in the foundation pit to 0.2m below the new construction reference surface;

[0014] Step 9: Clean all cement slurry stones exposed outside the water-stop curtain, leave 1m of exposed anchor rods, grouting pipes, secondary grouting pipes and orifice grouting pipes, and cut off the excess parts;

[0015] Step 10: After the cement slurry reaches the required strength, start installing the steel waist beam and tension and lock it;

[0016] Step 11: After tensioning and locking, cement and water glass double liquid slurry is injected through the hole grouting pipe to seal the gap between the cement slurry stone body of the anchor rod and the water-stop curtain interface, and at the same time, a circle of grouting body is formed around the anchor rod at the hole section.

[0017] Preferably, pressure grouting is used when injecting cement slurry.

[0018] Preferably, pressure grouting is used when injecting the double slurry of cement and water glass.

[0019] Preferably, the drilling rig casing is a multi-section casing, which is pulled out section by section.

[0020] Preferably, a steel plate is laid under the drilling rig.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The underwater anchor construction method applied to water-rich pebble strata ensures the consistency of the inclination angle of the anchor by pre-buried steel casings, while maintaining the water pressure balance inside and outside the foundation pit, thereby avoiding the occurrence of water and sand gushing, and adopts secondary grouting to compensate for the risk of cement slurry in the pebble layer being carried away by flowing groundwater. Finally, a method of injecting cement-water-glass double-liquid slurry at the orifice is adopted to ensure that the orifice does not leak. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0024] Figure 2 It is a schematic diagram of the structure after the steel waist beam is installed in the present invention.

[0025] The meanings of the numbers in the figure are: 1. Embedded steel casing; 2. Drill rod; 3. Water-stop curtain; 4. Secondary grouting pipe; 5. Anchor rod; 6. Grouting pipe; 7. Hole grouting pipe; 8. Steel waist beam. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] The present invention provides a technical solution:

[0028] An underwater anchor construction method for use in water-rich pebble formations, see Figure 1-Figure 2 , including the following steps:

[0029] Step 1: Construct a water-stop curtain 3 around the foundation pit to prevent or reduce the water from the side wall of the foundation pit from flowing into the foundation pit;

[0030] Step 2: Dig soil in the foundation pit to a height of about 0.2m above the water level in the foundation pit as the construction reference surface, and keep the water level inside the foundation pit equal to the water level outside the foundation pit;

[0031] Step 3: bury the embedded steel casing 1 which is larger than the drilling casing at the designed inclination angle at a distance of H / tanθ from the water-stop curtain. First, backfill and compact the pebbles and then inject cement slurry to fix the embedded steel casing 1. H is the vertical distance between the anchor rod and the construction reference plane in the foundation pit (the buried depth of the anchor rod); θ is the inclination angle of the anchor rod, which is also the inclination angle of the embedded steel casing.

[0032] Step 4: Use a hydraulic impact casing drill to drill along the embedded steel casing 1, penetrate the water-stop curtain 3 when it encounters it, and stop the drilling of the drill rod 2 and the drill bit of the drilling rig at the designed hole depth;

[0033] Step 5: After the hole is formed, clean the sand and rock chips in the hole. After cleaning, pull out the drill rod and drill bit;

[0034] Step 6: Insert the anchor rod 5, the grouting pipe 6, the secondary grouting pipe 4 and the hole grouting pipe 7 into the drilling rig casing, then inject cement slurry from the bottom of the hole through the grouting pipe, and pull out the drilling rig casing after the slurry overflows from the hole;

[0035] Step 7: After the cement slurry solidifies, cement slurry is injected through the secondary grouting pipe 4 for secondary grouting, and then the orifice grouting pipe 7 is opened with clean water pressure;

[0036] Step 8: Dig in the foundation pit to 0.5m below anchor rod 5 as the new construction reference surface, and at the same time lower the water level in the foundation pit to 0.2m below the new construction reference surface;

[0037] Step 9: Clean all cement slurry stones exposed outside the water-stop curtain, leave 1m of exposed anchor rods, grouting pipes, secondary grouting pipes and orifice grouting pipes, and cut off the excess parts;

[0038] Step 10: After the cement slurry reaches the required strength, the steel waist beam 8 is installed and tensioned and locked. As a result, the cement slurry stone body of the anchor rod and the bonding surface of the curtain are prone to shifting, resulting in gaps and water seepage.

[0039] Step 11: After tensioning and locking, cement and water glass double slurry is injected through the hole grouting pipe 7 to seal the gap between the cement slurry stone body of the anchor rod and the water-stop curtain interface. At the same time, a circle of grouting body is also formed around the anchor rod at the hole section to further prevent groundwater from seeping out of the anchor rod.

[0040] In this method, the drilling rig retreats a certain distance, and the inclination angle of the anchor rod is ensured to be consistent by pre-buried steel casing. At the same time, the water pressure inside and outside the foundation pit is kept balanced, which can avoid the occurrence of water and sand gushing. Secondary grouting is used to compensate for the risk of cement slurry in the pebble layer being carried away by flowing groundwater. Finally, the method of injecting cement-water-glass double liquid slurry at the orifice is used to ensure that the orifice does not leak.

[0041] Pressure grouting is used when injecting cement slurry; pressure grouting is used when injecting cement and water glass double liquid slurry.

[0042] The drilling rig casing is a multi-section casing, which is pulled out section by section when the casing is pulled out. The drilling rig casing is an existing conventional technical setting.

[0043] Lay steel plates under the drilling rig.

Claims

1. An underwater anchor construction method applied to water-rich pebble formations, characterized by: The following steps are involved: Step 1: construct a water-stop curtain (3) around the foundation pit; Step 2: Dig soil in the foundation pit to a height of 0.2m above the water level in the foundation pit as the construction reference surface, and keep the water level inside the foundation pit equal to the water level outside the foundation pit; Step 3: at a distance of H / tanθ from the water-stop curtain, a pre-buried steel casing (1) larger than the drilling casing is buried at a designed inclination angle, first backfill and compact pebbles, and then inject cement slurry to fix the pre-buried steel casing (1), H is the vertical distance between the anchor rod and the construction reference surface in the foundation pit, and θ is the inclination angle of the anchor rod; Step 4: Use a hydraulic impact casing drill to drill along the embedded steel casing (1), penetrate the water-stop curtain (3) when encountering it, and stop the drilling of the drill rod (2) and the drill bit of the drilling rig until the designed hole depth is reached; Step 5: After the hole is formed, clean the sand and rock chips in the hole. After cleaning, pull out the drill rod and drill bit; Step 6: inserting anchor rods (5), grouting pipes (6), secondary grouting pipes (4) and hole grouting pipes (7) into the drilling rig casing, and then injecting cement slurry from the bottom of the hole through the grouting pipes. After the slurry overflows from the hole, the drilling rig casing is pulled out; Step 7: After the cement slurry solidifies, cement slurry is injected through the secondary grouting pipe (4) for secondary grouting, and then the orifice grouting pipe (7) is opened with clean water pressure; Step 8: dig soil in the foundation pit to 0.5m below the anchor rod (5) as a new construction reference surface, and at the same time lower the water level in the foundation pit to 0.2m below the new construction reference surface; Step 9: Clean all cement slurry stones exposed outside the water-stop curtain, leave 1m of exposed anchor rods, grouting pipes, secondary grouting pipes and orifice grouting pipes, and cut off the excess parts; Step 10: After the cement slurry reaches a certain strength, the steel waist beam (8) is installed and tensioned and locked; Step 11: After tensioning and locking, cement and water glass double slurry is injected through the hole grouting pipe (7) to seal the gap between the cement slurry stone body of the anchor rod and the water-stop curtain interface, and at the same time, a circle of grouting body is formed around the anchor rod at the hole section.

2. The underwater anchor construction method applied to water-rich pebble formation according to claim 1 is characterized by: Pressure grouting is used when injecting cement slurry.

3. The underwater anchor construction method applied to water-rich pebble formation according to claim 1 is characterized in that: Pressure grouting is used when injecting cement and water glass double liquid slurry.

4. The underwater anchor construction method applied to water-rich pebble formation according to claim 1 is characterized by: The drilling rig casing is arranged in multiple sections, and is pulled out section by section.

5. The underwater anchor construction method applied to water-rich pebble formation according to claim 1 is characterized by: Lay steel plates under the drilling rig.

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