Grouting spiral anchor with expandable end and mounting method thereof
Technical Field
The invention relates to a screw anchor and a mounting method thereof, in particular to a grouting screw anchor with an expandable end and a mounting method thereof.
Background
In recent decades, the demand for oil and gas resources has increased sharply, so that the exploitation of oil and gas gradually goes from the land to the offshore and then to the deep sea, and large and ultra-large floating structures (floating platforms, ferries, floating trestles, floating wharves and the like) are gradually increased, thereby providing higher requirements for deep water mooring systems and developing corresponding novel deep water mooring basic types. In the last two decades, the Tension Leg Platform (TLP) has been proved to have good motion performance and is a platform form which is very suitable for oil and gas production in deep sea areas. The spiral anchor foundation can well meet the mooring requirement of a Tension Leg Platform (TLP), has the characteristics of simple and rapid installation, no need of excavation and continuous tunneling, and good mooring performance, and is a hot direction for future mooring foundation research.
The spiral anchor is installed simply and quickly, the spiral anchor is only required to be hoisted to a designated position through an installation ship, the anchor body is released, torque is applied through the installation hole, and the spiral anchor penetrates to the designated position through the spiral blade; however, when the screw anchor is in service, the bearing capacity is mainly exerted depending on the self weight of the anchor body and the frictional resistance of the soil body to the anchor body and the helical blade, the bearing capacity can only be exerted in a limited way, and in order to improve the bearing area of the anchor body and increase the bearing capacity, the grouting screw anchor with the expandable end part is provided.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a grouting screw anchor with an expandable end and a mounting method thereof. This kind of anchor type has inherited the spiral anchor simple to operate swiftly, need not the advantage of excavation, and makes the spiral anchor tip open through comparatively simple structural design, has increased the lifting surface area of anchor body, and then has improved the bearing capacity of anchor body, utilizes the MICP technique, sprays the slip casting, makes open the part and coheres with the seabed soil, improves the bearing capacity of anchor body.
The invention adopts the following technical scheme:
a grouting spiral anchor with an expandable end part comprises an anchor body, a spiral large blade, an anchor head, a spiral small blade, a guide rod and an anchor tail cover plate; the anchor body is of a variable cross section, a plurality of spiral large blades are uniformly distributed on the upper part of the anchor body, the cross section of the lower part of the anchor body is reduced, a plurality of blades are uniformly distributed around the lower part of the anchor body, the upper end of each blade is hinged with the variable cross section of the anchor body, all the blades are just tightly attached to the lower part of the anchor body when tightened, the overall diameter of the lower part of the anchor body is consistent with that of the upper part, a torsional spring is arranged on the hinge, and the torsional spring can control the maximum; grouting branch pipes are arranged in the blades; the anchor head is of a cone structure and is arranged at the lower end of the anchor body, and a small spiral blade is distributed on the anchor head; the anchor tail cover plate is arranged at the upper end of the anchor body, the guide rod is vertically arranged in the inner space of the anchor body, the upper end of the anchor tail cover plate penetrates out of the anchor tail cover plate, the penetrating end of the guide rod is provided with a blocking ring, the blocking ring is used for limiting the guide rod to move downwards, a grouting hole is formed in the blocking ring and is connected with a grouting pipe arranged in the guide rod, and the grouting pipe is communicated with a grouting branch pipe in the blade; each blade is provided with a reserved hole, the tail end of the guide rod is provided with a buckle, the anchor body is provided with a corresponding opening, and the buckle penetrates through the opening of the anchor body and restrains the blade on the anchor body through the reserved hole; the upper part of the guide rod is provided with a stop block for enabling the guide rod to continue to move upwards when the blades are unfolded to the maximum limit, the top end of the guide rod is provided with a mooring rope hole for connecting a mooring steel cable, and the anchor tail cover plate is provided with a lifting lug for connecting and installing the steel cable; the upper end of the anchor body is provided with a mounting hole for applying torque during mounting.
In the above technical scheme, further, the grouting branch pipes of the blades are vein-shaped.
Furthermore, the thickness of the blade is controlled to be one third of the radius of the upper part of the anchor body.
Further, the maximum angle of the torsion spring is controlled to be 70-80 degrees.
The installation method of the expandable-end grouting screw anchor is as follows:
during site operation, the spiral anchor is adjusted to an appointed installation position by utilizing an installation steel cable for an installation ship, the verticality of the anchor body is guaranteed, the anchor body is released, torque is applied to the installation hole to enable the spiral anchor to spirally penetrate into a seabed to an appointed depth under the action of a large helical blade and a small helical blade, a mooring steel cable is tensioned, a guide rod moves upwards along a central shaft, the constraint on the blade is relieved through a reserved hole by a buckle at the moment, the blade is opened under the elastic action of a torsional spring, after the maximum opening angle of the torsional spring is reached, jet grouting is carried out through a grouting hole, grout is cemented with seabed soil, and installation is completed at the moment.
The technology of MICP (microbial induced calcium precipitation) can be used for grouting, the grouting liquid is cultured by adopting a CASO AGAR + urea (20g/L) culture medium at the temperature of 30 ℃ and the pH value of 7.3 until OD600= 1.0 is obtained to prepare bacterial liquid, calcium acetate and urea solution which are 1mol/L are prepared and mixed according to the volume ratio of 1:1 to prepare nutrient salt, and 100 mL of prepared bacteria are preparedMixing the solution with 1L of nutrient salt to obtain bacterial agent, treating each 1L of bacterial agent for 25cm3And (4) a part to be processed.
The invention has the following advantages:
the stress area of the anchor body is increased by opening the blades at the end part of the spiral anchor, so that the bearing capacity of the anchor body is improved; torque is applied, underwater continuous spiral penetration is carried out by using the spiral blade, the penetration resistance is small, excavation is not needed, and the installation is convenient; the end blades are internally provided with grouting pipes for injecting grouting, so that a cemented umbrella cover can be formed, and the bearing capacity is improved.
Drawings
FIG. 1 is a schematic view of the construction of an anchor body of the present invention prior to tensioning;
FIG. 2 is a front cross-sectional view of the anchor body of the present invention prior to tensioning;
FIG. 3 is a top plan view of the anchor body of the present invention prior to tensioning;
FIG. 4 is a bottom plan view of the anchor body of the present invention prior to tensioning;
FIG. 5 is a front cross-sectional view of the anchor body of the present invention after tensioning;
FIG. 6 is a bottom plan view of the anchor body of the present invention after tensioning;
FIG. 7 is a schematic illustration of blade grouting.
In the figure: 1. anchor body, 2, spiral big blade, 3, anchor head, 4, blade, 5, spiral little blade, 6, guide rod, 7, slip casting pipe, 8, torsional spring, 9, hinge, 10, preformed hole, 11, buckle, 12, stop block, 13, anchor tail cover plate, 14, slip casting hole, 15, mooring cable hole, 16, mooring steel cable, 17, lug, 18, mounting hole, 19, stop ring, 20, cementation zone, 21, slip casting branch pipe.
Detailed Description
The technical solution of the present invention is further explained by a specific example, but the solution of the present invention is not limited thereto.
Referring to fig. 1-7, a grouting screw anchor with an expandable end is characterized in that the end is provided with four blades which can rotate around a pin in a hinged mode, a guide rod is tensioned when the grouting screw anchor is spirally penetrated to a specified penetration depth, so that the blades are separated from the restraint of a buckle and expand under the action of a torsion spring, the stress area of the grouting screw anchor and seabed soil is enlarged, grouting is performed, and the MICP technology is adopted for grouting, so that the bearing capacity of the anchor is improved. Specifically, the structure is as follows: a grouting spiral anchor head 3 is conical, a small spiral blade 5 is arranged at the anchor head for spiral penetration, four blades 4 are uniformly hinged at the variable cross section of an anchor body 1 through hinges 9, when the blades 4 are tightened, the cross section area of the anchor body 1 is ensured to be unchanged, a grouting branch pipe 21 is arranged in each blade 4, a reserved hole 10 is arranged at the upper end of each blade 4 and used for a buckle 11 to restrain the blade 4 through the reserved hole 10, a torsion spring 8 is arranged between each blade 4 and the anchor body 1, the maximum opening angle of the torsion spring 8 is set to be 70-80 degrees, the buckle 10 is arranged at the tail end of a guide rod 6, an anchor tail cover plate 13 extending out of the upper end of the guide rod 6 is provided with a blocking ring 19, the diameter of the blocking ring 19 is larger than the inner diameter of an anchor tail center hole and used for limiting the guide rod 6 to move downwards, a blocking block 12 is arranged at the upper part of the guide rod 6, the radius of the blocking, the buckle 11 moves upwards, the constraint on the blade 4 is relieved through the preformed hole 10, and after the constraint is relieved, the blade 4 is opened to the maximum opening angle of the torsion spring 8 under the action of the torsion spring 8. The blocking ring 19 is provided with a grouting hole 14, the grouting hole 14 is connected with a grouting pipe 7 arranged in the guide rod 6, the grouting pipe 7 is connected with a grouting branch pipe 21 in the blade 4, the uppermost end of the guide rod 6 is provided with a mooring hole 15 which is connected with a mooring steel cable 16, two lifting lugs 17 are welded at the symmetrical part of the outer side of the anchor tail and used for connecting and installing the steel cable, and the anchor tail is provided with an installation hole 18 which is used for applying torque during installation. The upper part of the anchor body 1 is uniformly provided with the large spiral blades 2 for spiral penetration during spiral anchor installation.
During on-site construction, a mounting steel cable and a mooring steel cable are connected in advance, an anchor body is adjusted to a specified mounting position through the mounting steel cable for a mounting ship, the verticality of the anchor body is guaranteed, the anchor body is released, torque is applied to the mounting hole to enable the anchor body to spirally penetrate into a seabed for a specified depth, the mooring steel cable 16 is stretched, a guide rod 6 moves upwards along a central shaft, a buckle 11 at the tail end of the guide rod 6 moves upwards along with the guide rod 6, when the buckle 11 moves to the upper portion of a preformed hole 10 in a blade 4, constraint on the blade 4 is completely removed, the blade 4 pops out under the action of a torsion spring 8 and stretches to the maximum angle of the torsion spring 8, jet grouting is performed through a grouting hole 14 in a blocking ring 19 at the moment, the grouting can adopt the MICP technology, the grout is injected to the blade 4, the blade 4 is cemented with seabed soil.
The installation process of the invention is as follows:
1. pre-connecting and installing a steel cable and a mooring steel cable;
2. hoisting the anchor body to a preset position by using an installation vessel;
3. the perpendicularity of the anchor body is guaranteed, the steel cable is installed in a loosening mode, and the anchor body is released;
4. applying torque at the mounting hole to enable the anchor body to spirally penetrate into the seabed by a specified depth;
5. stretching the mooring steel cable, pulling the guide rod, and releasing the constraint of the buckle on the blade to open the blade;
6. carrying out underwater jet grouting in the grouting holes, and cementing the slurry and the seabed soil by using an MICP technology;
and finishing the installation.