KR101582068B1 - Ground anchor construction method for anchoring area extended improvement using extended excavation agitator - Google Patents

Abstract

The present invention provides a ground anchor construction method for anchoring area extended improvement using an extended excavation agitator, which can reduce an amount of an anchor for construction, shorten a construction period, and reduce a construction cost. According to a preferred embodiment of the present invention, the method comprises the following steps of: (a) performing drilling work; (b) forming an extended bore; (c) placing an extended excavation agitator inside a front end portion of an out casing; (d) forming an internal cement bore; (e) drawing out the extended excavation agitator to the outside of the out casing; (f) placing an inner member of an anchor assembly within a cement bore of an anchoring area; and (g) drawing out and removing the out casing on the earth and sand ground before a grout fluid is hardened in the (d) step.

Description

Technical Field [0001] The present invention relates to a ground anchor construction method and an extended anchor construction method using an enlarged excavation apparatus,

The present invention relates to a method for constructing an improved anchor for an anchorage field using an enlarged excavation apparatus, and more particularly, to a method for constructing an anchor for an anchorage of an improved anchorage field by an enlarged excavation and a grout material, The present invention relates to an improved anchor construction method using an enlarged excavation stirrer for reducing an amount of construction of an anchor by reducing cushion bulges in the interior of the anchor and reducing the construction cost and construction cost of the anchor.

In general, when a ground anchor is to be settled on the soil (especially the soft soil with an N value of 15 or less), the target fixation force (bearing capacity of the anchor) is constant And the shear stress of the ground is limited due to the characteristics of the slope soils. Therefore, there is a limit to the settlement force which can be settled per one anchor.

Therefore, the number of anchors to be installed also increases, resulting in an increase in the construction cost and construction period, as well as a decrease in construction quality due to the influence of the anchorpost overlapping between the anchors and the anchor holes in the perforated (flush) The horizontal spacing of the ball), the perforation of the perforation, and the settlement of the backside ground due to the clay process of the excavation slime.

Korean Patent No. 10-0673579 (ground anchor reinforced with geosynthetic fibers and anchor construction method using the same) has been proposed as a background of the present invention. This is accomplished by inserting a plurality of ground anchors, which are jackets of geosynthetic fiber fabricated in the shape of a turret, which surrounds the inner lower body connected to one side of the PC steel wire bundle, with the ground anchors surrounding the lower inner body at regular intervals, The fixing force for fixing and fixing the PC steel wire bundle by tensing can be improved.

However, the above background art has a limit in increasing the pulling resistance of the anchor steel hull because it can not have a cross-sectional structure formed from the center of the section in the anchoring steel section, the deep-section bulb body, and the soilless cement bulb body.

Korean Patent No. 10-0673579 (Ground Anchor Reinforced with Geosynthetic Fiber and Anchor Construction Method Using the Same)

In the present invention, an enlarged bulge forming sill cement is formed by an enlargement excavation and a grout material injection in a primary settlement section, and a cement bulb is formed inside a secondary enlarged bulb to increase the tension of an anchor, And an object of the present invention is to provide an improved ground anchor construction method using an enlarged excavation agitator capable of shortening the construction time and reducing construction cost.

According to a preferred embodiment of the present invention,

(a) introducing an outcasing to a free ground section in a soil layer and performing a boring operation through the inside of the outcasing;

(b) Expansion drilling After inserting the stirring device into the inside of the outcasing, the grout solution is injected through the inner passage of the inner rod, and the mixture is injected at the tip of the enlarged excavation agitator, Forming an enlarged bulb forming the soil cement in the settling section;

(c) further introducing the outcasing to the final length of the anchorage section, so that the enlarged excavation agitator is positioned inside the distal end of the outcage;

(d) re-injecting the grout solution at the tip of the enlarged excavation stirring device to grout the inside of the outcasing to replace the soil cement with cement at the center of the enlarged bulb to form an inner cement bulb;

(e) pulling out the enlarged excavation stirring device located at the distal end of the outcasing to the outside of the outcasing;

(f) inserting an anchor assembly into the inside of the outcasing to place the inner bottom of the anchor assembly within the cement bulb of the anchorage section;

and (g) drawing out the outer casing from the soil foundation before the grouting solution is hardened in the step (d).

Further, the method may further include the step of grouting the inside of the packer after the step (g) after adding the packer to the anchor assembly in the step (f).

Further, in the above-mentioned enlarged excavation stirring apparatus,

An inner rod adapter connected to the inner rod;

A grout injection shaft having one end connected to the inner rod adapter, a grouting shaft main body screwed to the shaft connection port, a grout injection shaft having a plurality of grouting discharge holes and having a bit screwed into the grouting shaft main body;

A stationary-side hinge block inserted into the grout injection shaft and positioned close to the bit and integrally fixed to the grout injection shaft;

A movable hinge block movably inserted into the grout injection shaft and positioned between the inner rod adapter and the fixed-side hinge block;

A swinging blade having one end hinged to the movable hinge block in a rotatable manner;

A lever having one end hinged to the fixed side hinge block and the other end hinged to the stirring vane;

And a stirring blade expanding spring inserted into the outer diameter portion of the grouting shaft and positioned between the inner rod adapter and the movable side hinge block to provide an expansion force for expanding the stirring blade during compression .

Further, the stirring vanes are arranged at intervals of 90 degrees around the grout injection shaft.

In addition, a key groove is formed on the inner surface of the inner rod adapter so as to maintain the compression force until the stirring vane expanding spring is compressed and then exits the front end of the out casing, and a stirring vane expanding spring is disposed in the grout injection shaft And a lock key for coupling with the key groove is further formed.

Further, the stirring blade is further provided with a stopper for stirring blade, which is positioned between the stirring blade and the lever and is fixed to the shaft for injecting grout to limit the rotation angle of the stirring blade to a predetermined value when the stirring blade is rotated and expanded .

According to the method of the present invention for enlarging the anchorage area by the enlarged excavation stirring apparatus, the enlarged bulge forming the soil cement is formed by the enlarging excavation and the jetting of the grout material in the first settlement section, It is also possible to increase the tension of the anchor by increasing the allowable adhesive force of these enlarged bulbs and cement bulbs by forming more cement bulbs. Therefore, the construction quantity of the anchor can be reduced and the air shortening and the construction cost can be reduced.

In addition, the enlarged digging and tilting apparatus can automatically expand the excavation wing at the moment when the agitating wing exits the front end of the out casing to be enlarged and excavated. After the enlarging excavation, the agitating wing is automatically folded It is easy to pull and remove by being loaded into the casing, and it is advantageous that no separate driving power is required for the expansion operation of the stirring blades.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate exemplary embodiments of the invention and, together with the description, serve to explain the principles of the invention, Shall not be construed as limiting.
FIGS. 1 to 7 are diagrams showing a construction state according to a process sequence of an anchorage enlargement improvement anchor construction method using an enlarged excavation stirring apparatus according to the present invention.
8 is an enlarged cross-sectional view taken along line AA of Fig.
9A and 9B are construction diagrams showing a state in which a packer is installed in an anchor assembly during an anchorage enlargement improvement type ground anchor construction using an enlarged excavation stirring apparatus according to the present invention.
10 is a perspective view of an enlarged excavation stirring apparatus according to an embodiment of the present invention.
Fig. 11 is a state in which the agitating blade is extended and opened in Fig. 10; Fig.
12 is a front sectional view of Fig. 10; Fig.
Fig. 13 is a front sectional view of Fig. 11; Fig.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the embodiments shown in the accompanying drawings, but the present invention is not limited thereto.

First, a fixing anchorage enlargement type improved ground anchor construction method using an enlarged excavation stirring apparatus of the present invention will be described.

Out casing  Punching work by

First, as shown in FIG. 1, the outcasing 7 is introduced into the soil layer 1 up to the free long section S1, and a drilling operation is performed through the inside of the outcasing 7. The out casing 7 is mounted on an unillustrated drilling machine and driven by intrusive rotation. The drilling operation can be performed, for example, by supplying water pressure to the inside of the outcasing 7.

Enlarged bulb forming work (enlarged excavation and Soil cement Stirring )

Then, as shown in Figs. 2 and 3, the enlarged excavation stirring apparatus 10 is inserted into the inside of the outcasing 7.

Thereafter, the grout liquid is injected through the inner passage of the inner rod 5 and injected from the front end of the enlarged excavation stirring apparatus 10, and at the same time, S2 to form an enlarged bulb 200 constituting the soil cement.

At this time, the stirring operation is performed between the grout solution and the soil to form soilless cement in the fixing section S2, and then the enlarged bulb 200 is formed when the soil cement is cured.

Out of casing  Additional penetration Stirring device Out casing  )

Then, as shown in Fig. 4, an operation of penetrating the outcasing 7 further deeper into the fusing section S2 is performed. As a result, the enlarged excavation stirring apparatus 10 is pulled into the distal end portion of the out casing 7 and positioned.

The structure of the enlarged excavation stirring device 10 to be drawn into the inside of the out casing 7 will be described later.

When the enlarged excavation stirring apparatus 10 is pulled into the inside of the out casing 7, there is a clearance space between the enlarging excavation stirring apparatus 10 and the out casing 7, The conditions for filling the liquid are established.

Internal cement bulb forming work

Then, as shown in FIG. 4, the grout liquid is injected through the inner rod 5 and the grout liquid is re-injected from the tip of the enlarged excavating and stirring apparatus 10.

The re-sprayed grout liquid exits the enlarged excavation stirring apparatus 10 and fills the inside of the out casing 7. At this time, the soil cement located at the center of the enlarged bulb 200 is pushed out from the inside of the outcasing 7 and has a cement bulb 210 replaced with cement in the fixing zone S2.

Therefore, the injection of the grout liquid is terminated when the soil cement exits the outcasing 7.

Enlarged excavation Stirring device Draw

Then, as shown in Fig. 5, an enlarged excavation stirring apparatus 10 located at the distal end of the outcasing 7 is pulled out of the outcasing 7.

At this time, since the grout liquid can escape by a volume corresponding to the length of the enlarged excavation stirring apparatus 10 and the inner rod inserted into the outer casing 7, it is possible to supplement the grout liquid additionally in small amount after the outcasing of the outcasing 7 have.

Anchor assembly installation

6, an anchor assembly 300 composed of a covered strand 310 and an inner bottom body 320 is inserted into the outcasing 7. At this time, the anchor assembly 300 is inserted such that the inner bottom body 320 is positioned in the cement bulb 210 in the fixing section S2.

Out casing Draw

Then, as shown in Fig. 7, the outcasing 7 is pulled out from the soil layer 1 before the grout liquid is hardened.

When the soil cement and the cement are cured, the inner bottom body 320 is installed at the center of the cement bulb 210 in the enlarged bulge 200 of the fixing section S2 in the soil foundation so that the anchor force can be exerted .

According to this method, the anchor assembly 300 is not attached directly to the soil cement bulb 210 but is attached through the inner cement bulb 210 as shown in FIG. 8 in the fixing section S2.

Therefore, when a tension force is generated in the anchor assembly 300, a shearing stress is generated between the inner cement bulb 210 and the enlarged bulb 200 composed of the soil cement to increase the allowable design tension of the anchor assembly 300 . For this reason, it is possible to reduce the amount of construction of the anchor, thereby shortening the construction time and construction cost.

That is, the allowable anchor tension (T _a ) = π × d _e × S ₂ × τ _a ,

- d _e : Expansion of the settlement section The diameter (cm) of the aged soil cement bulb

- S ₂ : Length of settlement length (cm)

- τ _a : Allowable shear stress (Kg / cm ² )

d _e = 40 cm, S ₂ = 800 cm and N = 5, the allowable anchor tension (T _a ) is 3.14 x 40 x 800 x 0.09 x 5 = 45,216 kg (45.216 ton).

On the other hand, when the allowable adhesive force Fs between the enlarged bulges 300 of the inner cement bulb 210 and the fusing long section S2 is calculated by the secondary injection,

Allowable Adhesive Force (Fs) = π × d _a × S ₂ × τ _s = 3.14 × 15 × 800 × 15/4 = 141,300 Kg (141.3 tons)

- d _a : Outcasing diameter of settlement section (cm)

- τ _s : Allowable Shear Stress (Kg / cm ² )

(τ _s = q _u / 4, q _u = Unconfined compressive strength of the stirring-up soil cement bulb, with the proviso that q _u = 15 kg / cm ² )

Therefore, Fs / T _a = 3.13? 1.2.

The diameter of the enlarged stirring cement bulb 210 was 40 cm and the uniaxial compressive strength q _u was 8 kg / cm ² The permissible tension of the anchor assembly 300 can be designed up to 45.2 tons and the allowable design tension force of the anchor according to the N value of the settlement section S2 and the length of the anchorage field, Can be increased.

Meanwhile, in the step of installing the anchor assembly in the present method, the packer 330 may be added to the anchor assembly 300, and grouting may be performed to the inside of the packer 330 after the outcasing 7 is pulled out.

At this time, when the grouting is performed to the inside of the packer 300, the packer 300 expands to the inner surface of the punched hole of the out casing 7, so that the drawing resistance of the anchor can be further increased.

Meanwhile, an enlarged excavation stirring apparatus 10 used in the present method will be described.

10 to 12, the enlarged excavation stirring apparatus 10 includes an inner rod adapter 12, a grout injection shaft 14, a fixed side hinge block 16, a movable side hinge block 18, a stirring blade 20 A lever 22, and a stirring blade expanding spring 24. As shown in Fig.

The inner rod adapter 12 has a cylindrical shape and one end thereof is connected to the inner rod 5 on the side of the drilling rig by screw connection so as to connect the grouting rod 14 to the inner rod 5 so as to rotate integrally.

The grout injection shaft 14 includes a shaft coupling 142 whose one end is connected to the inner rod adapter 12, a grouting shaft main body 144 screwed to the shaft coupling 142, a plurality of grouting discharge holes 146a And a bit 146 screwed to the grouting shaft body 144. The bit 146 is provided on the grouting shaft body 144, The grout injection shaft 14 has a grouting injection passage 14a communicating with the inner rod 5 therein. In the present embodiment, the grouting discharge holes 146a are provided both in the direction perpendicular to the longitudinal direction of the grouting grooves 14 and in the oblique direction.

The fixed side hinge block 16 is inserted into the grout injection shaft 14 and positioned near the bit 146 and welded to the grout injection shaft 14. The movable side hinge block 18 is movably inserted into the grout injection shaft 14 and is positioned between the inner rod adapter 12 and the fixed side hinge block 16. At this time, the fixed side hinge block 16 and the movable side hinge block 18 have a rectangular cross section smaller than the cross sectional size of the outcasing 7.

The stirring vane 20 has a plate-like structure in which one end is rotatably hingedly connected to the movable hinge block 18 via a pin 19. In the present embodiment, the stirring vane 20 is configured such that its distal end is located at the movable hinge block 18 when the stirring vane 20 is folded (before expansion) as shown in Figs. 10 and 12 But it may be longer. The lever 22 is hinged at one end to the fixed side hinge block 16 via a pin 17 and the other end is hinged to the stirring vane 20 through a pin 21. The agitating blades 20 are arranged around the grouting shaft 14 at intervals of 90 degrees. Of course, the corresponding levers 22 are connected one by one for each of the stirring blades 20. Therefore, in the present embodiment, a total of four stirring vanes 20 perform a sliding operation for enlarged excavation.

The stirring blade expanding spring 24 is inserted into the outer diameter portion of the grouting shaft 14 and is positioned between the inner rod adapter 12 and the movable side hinge block 18. [ Thus, the stirring blade expanding spring 24 provides an expanding force to cause the stirring blade 20 to spread during compression.

Here, a key groove 144a is formed on the inner surface of the inner rod adapter 12 so as to maintain a compressive force until the stirring blade expanding spring 24 is compressed and then exits the front end of the outer casing 7, The injection shaft 14 is further provided with a lock key 144a for engaging with the key groove 144a in the section where the stirring blade extension spring 24 is located.

In addition, when the stirring vane 20 is extended and rotated, it is positioned between the stirring vane 20 and the lever 22 so as to limit the rotation angle within a predetermined range, and is fixed to the grouting shaft 14 And a stopper 144b for a stirring blade is further provided.

The enlarged excavation stirring apparatus 10 constructed as described above is charged into the outer casing 7 without compressing the stirring vane expanding spring 24 for the enlarged bulb forming operation and pushes the inner rod 12 When rotated, the stirring blade extension spring 24 is compressed and the key groove 122 is engaged with the key 144a.

The stirring vane 20 is supported by the movable side hinge block 18 which receives the compressive force of the stirring blade expanding spring 24 in the inside of the out casing 7 and the lever 22 connected to the fixed side hinge block 16 side ) And have an expanding power to stand up.

Then, when the mixer 20 is pulled out of the out casing 7, the stirring vane 20 is opened by the expansion force corresponding to the compression force of the stirring vane expanding spring 24 until the stirring vane stopper 144b stops as shown in FIGS. 11 and 14 It is rotated and expanded.

Therefore, in the enlarged bulb forming operation step, the stirring vane 20 is rotated in the open state and the grouting solution is discharged through the grouting discharge hole 146a, so that excavation and stirring work are simultaneously performed to form the enlarged bulb 200 made of the soil cement .

In addition, in the additional penetration step of the out casing, the front end of the out casing 7 pushes the stirring vane 20 from the back side, and the operation is performed again as shown in FIG. At this time, the movable side hinge block 18 is moved backward.

In the inner cement bulb forming work step, the cement discharged through the grouting discharge hole 146a of the grouting injection shaft 14 is filled through the passage formed between the grouting injection shaft 14 and the out casing 7 So that the inner cement bulb 210 is formed thereafter.

Thus, the enlarged excavation stirring apparatus 10 can expand the stirring vane 20 mechanically by the stirring vane expanding springs 24 without using any additional power, thereby eliminating the need for an electric power unit, This simplifies the manufacturing process and reduces the risk of failure.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art in light of the above teachings. will be. The invention is not limited by these variations and modifications, but is limited only by the claims appended hereto.

7: Out casing
10: Magnified excavator
12: Inner rod adapter
14: Shaft for grouting injection
144a: Rock Key
144b: keyway
16: Fixed side hinge block
18: movable side hinge block
20: stirring blade
22: leverage
24: Spring for stirring blade expansion
200: enlarged bulb
210: Cement bulbs
300: anchor assembly
320: My lower body
330: Packer

Claims (6)

(a) introducing an outcasing 7 to a free ground section S1 in the soil foundation 1 and performing a drilling operation through the interior of the outcasing 7;
(b) In-situ excavation After the stirring apparatus 10 is inserted into the inside of the outcasing 7, the grout solution is injected through the inner passage of the inner rod 5 and injected from the tip of the enlarged excavation stirring apparatus 10 And forming an enlarged bulb (200) forming a silicate cement in the settling length section (S2) through an enlarging excavation and a stirring operation of the enlarged excavation stirring device (10);
(c) further introducing the outcasing (7) to the focal point of the fusing section so that the fusing and stirring device (10) is located inside the tip of the outcasing (7);
(d) The grout solution is re-injected from the tip of the enlarged excavation stirring device 10 to grout the inside of the outcasing 7 to replace the soil cement with cement at the center of the enlarged bulb 200, Forming a bulb (210);
(e) drawing out the enlarged excavation stirring device (10) located at the distal end of the outcasing (7) to the outside of the outcasing (7);
(f) inserting an anchor assembly (300) into the inside of the outcasing (7) to place the inner lower body (320) of the anchor assembly (300) in the cement bulb (210) between the fixing cages;
(g) withdrawing and removing the outcasing 7 from the soil layer 1 before the grouting solution is cured in the step (d)
The enlarged excavation stirring apparatus (10)
An inner rod adapter 12 connected to the inner rod 5;
A grout shaft main body 144 which is threadedly coupled to the shaft connecting hole 142 and a plurality of grouting discharge holes 146a which are connected to the inner rod adapter 12 at one end, A shaft 14 for grouting with a bit 146 screwed into the groove 14;
A fixed side hinge block 16 inserted into the grouting shaft 14 and positioned close to the bit 146 and integrally fixed to the grouting shaft 14;
A movable side hinge block 18 movably inserted into the grouting hole 14 and positioned between the inner rod adapter 12 and the fixed side hinge block 16;
A stirring vane (20) having one end hinged to the movable hinge block (18) in a rotatable manner;
A lever 22 having one end hinged to the fixed side hinge block 16 and the other end hinged to the stirring vane 20;
And is inserted into the outer diameter portion of the grout injection shaft 14 so as to be positioned between the inner rod adapter 12 and the movable hinge block 18 so as to provide an expansion force for expanding the stirring vane 20 during compression. And a wing extension spring (24). The method of the present invention includes the steps of: The method according to claim 1,
Further comprising the step of grouting the inside of the packer (330) after the step (g) after adding the packer (330) to the anchor assembly (300) in the step (f) An improved ground anchor construction method using a device. delete The method according to claim 1,
Wherein the stirring vanes (20) are disposed at intervals of 90 degrees around the grout injection shaft (14). The method according to claim 1,
A key groove 144a is formed on the inner surface of the inner rod adapter 12 to maintain a compressive force until the agitating vane expanding spring 24 is compressed and then exits the front end of the out casing 7, Characterized in that a lock key (144a) for engaging with a key groove (144a) is formed in a section where the stirring blade extension spring (24) is located in the use shaft (14) Improved ground anchor construction method. The method according to claim 1,
The stirring blade 20 is positioned between the stirring blade 20 and the lever 22 so as to limit the rotation angle within a predetermined range when the stirring blade 20 is rotated and expanded, And a stopper (144b) for a wing is further provided. The method for constructing an improved anchorage enlarging type ground anchor using the enlarged excavation stirring device.

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