KR101841876B1 - CIP Retaining Wall and Method Constructing the Same - Google Patents

Abstract

The present invention relates to a CIP retaining wall, and a construction method thereof. According to the present invention, a retaining wall structure which can be easily installed by using a steel pipe and has improved stiffness is constructed such that the construction of the retaining wall structure by placing shotcrete can be facilitated.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CIP (Retaining Wall)

The present invention relates to a CIP earth retaining wall, and more particularly, to a CIP retaining wall using a CFT steel pipe for easily installing a reinforced concrete retaining structure using a steel pipe and reinforcing the stiffness of the concrete, And a construction method thereof.

The construction method of the cast-in-place pile (CIP) wall is one of the construction methods to construct the earth retaining walls to prevent the collapse of the surrounding ground due to excavation during the excavation work for the construction of underground structures. After drilling to the required depth with a large-sized excavator, the concrete piles are successively installed in the ground in the perforated holes to form the retaining wall by the main heat type.

This CIP method can be applied to almost all ground without regard to the ground conditions. When excavation is completed, it is possible to construct an underground structure with underground walls, It is possible to maximize the construction space of underground structures in the land and maximize the land use rate.

On the other hand, when the groundwater level is high or soft ground, the steel wall casing is used in order to prevent the collapse of the pore wall or the relaxation of the surrounding ground during drilling.

Steel pipe casings should be installed in the ground at the same time as excavation by earth auger. When reinforcement and pouring of concrete in the hole are completed, concrete is pulled out before curing and reused.

Since the back earth pressure on the earth retaining walls in the excavation works or the ground with high groundwater level is much larger than that in the general case, the rigidity of the retaining walls is increased by embedding the H - shaped steel in the CIP concrete at regular intervals.

In the excavation work of the great center, usually, the lower part of the depth is formed by the rock. In this case, as shown in FIG. 1, the CIP pile in which the H-shaped steel is not buried is installed only up to the toe layer on the upper part of the rock layer, and the H-shaped steel buried in the concrete is extended to the required depth of the rock layer to reinforce the CIP pile After excavation of the rock layer, it is used as a thumb pile to install soil plate or shotcrete to complete the earth retaining wall.

However, H-beams are not expensive because they are expensive, and construction costs are increased.

Therefore, in recent years, attempts have been made to use CFT (Concrete Filled Tube) steel pipes, which are recognized to exert high rigidity due to the effect of synthesis or constraint of steel pipe and concrete, for reinforcing the rigidity of the earth retaining wall.

Instead of embedding the H-beam in the CIP concrete, the wall of the retaining wall used for reinforcing the CFT steel pipe inserts the steel pipe into the perforation hole and uses the concrete as a part of the CIP wall.

This method has advantages in that it is easier to construct and more economical than the method of embedding H-shaped steel in existing CIP concrete. However, when excavation of rock mass at large depth and construction of earth retaining wall is required, CFT steel pipe There is a problem in that it is not easy to install a soil plate or a reinforcement steel for pouring a shotcrete by using the cross-sectional characteristics.

Korean Unexamined Patent Publication No. 10-2012-0040780 (Publication date: April 30, 2012), title of invention: "connection structure for constructing main building type cladding wall with synthetic wall used as part of underground construction wall"

In order to solve the above problems, the present invention provides a CIP mud wall structure using a CFT steel pipe which is easy to install using a steel pipe and has a reinforced stiffness, and which facilitates the construction of a retaining structure by casting a shotcrete. And its object is to provide a construction method thereof.

According to an aspect of the present invention, there is provided a CIP earth mooring structure comprising:

And a pile of a thumb which is arranged at a predetermined distance between the pile and the pile, and which is installed at a depth deeper than the pile of the pile,

The thumb pile has a cylindrical shape hollowed out so that the filled concrete is poured therein, a plurality of screw grooves are formed in the circumferential direction on the inner surface of the lower end, and a plurality of engaging grooves having a predetermined depth in the circumferential direction are formed on the screw groove Upper steel pipe; And

A plurality of threaded portions formed on an outer circumferential surface of the threaded portion and having a diameter smaller than the diameter of the upper steel pipe and having a plurality of threaded protrusions protruding in a ring shape to be inserted into the threaded portion, And a lower steel pipe extending from the fastening member, the lower steel pipe being formed in a hollow cylindrical shape and having a frusto-conical rotating member formed on a lower surface thereof.

 A method of constructing a CIP earth retaining wall according to an aspect of the present invention includes:

Providing a thumb pile so that the tip portion is inserted up to a certain depth of the rock layer at regular intervals and making the connecting member attached to the thumb pile face the excavation surface;

Establishing a continuous thermal underground continuous wall by providing a pile between the thumb pile and the thumb pile;

Exposing a connecting member attached to the thumb pile by excavating a front surface of the continuous earth continuous wall;

Constructing the earth retaining structure on the rock excavation surface between the thumb pile and the thumb pile using the connecting member;

A grid-like reinforcing bar is provided between the connecting member and the connecting member, and a shotcrete is installed to fill the grid-like reinforcing bars.

According to the above-described construction, the upper steel pipe and the lower steel pipe are combined to form a thumb pile, so that the steel pipe can have a large strength and an easy installation.

The present invention has the effect of facilitating the installation of the earth retaining structure by installing the shotcrete in the lower steel pipe.

1 is a perspective view illustrating the construction of a conventional CIP earth retaining wall according to the related art.
FIG. 2 is a perspective view showing a CIP earth retaining wall constructed according to an embodiment of the present invention.
3 is a perspective view showing the shapes of the upper steel pipe and the lower steel pipe according to the embodiment of the present invention.
FIG. 4 is a cross-sectional view illustrating a joint portion between an upper steel pipe and a lower steel pipe according to an embodiment of the present invention.
5 is a perspective view illustrating a configuration of a rotating member according to another embodiment of the present invention.
6 is a view showing a configuration of a connecting member according to the first and second embodiments of the present invention.
7 is a view illustrating a configuration of a connection member according to a third embodiment of the present invention.
8 is a view showing a grid reinforcing bar installed between CFT piles for installing the earth retaining structure according to the embodiment of the present invention.
FIG. 9 is a view showing a concrete installation of shotcrete after a reinforcing bar for lattice is installed between CFT piles according to an embodiment of the present invention. FIG.

Throughout the specification, when an element is referred to as "comprising ", it means that it can include other elements as well, without excluding other elements unless specifically stated otherwise.

FIG. 2 is a perspective view illustrating a state in which a CIP earth retaining wall according to an embodiment of the present invention is installed, FIG. 3 is a perspective view illustrating a shape of an upper steel pipe and a lower steel pipe according to an embodiment of the present invention, FIG. 5 is a perspective view illustrating the structure of a rotary member according to another embodiment of the present invention. Referring to FIG.

The present invention uses a thumb pile to reinforce a wall in constructing a CIP earth retaining wall, eliminating the existing H-shaped steel and applying a CFT pile using an inexpensive steel plate to easily form a soil retaining structure such as a soil plate Can be installed.

The CIP earth retaining walls according to the embodiment of the present invention may include a plurality of in-situ piles 10 connected to each other and arranged in a row and arranged at regular intervals between the in-situ piles 10, It consists of a CFT pile, which is a thumb pile constructed with deep depth.

And a toothed wall 20 formed by shotcrete at the lower part of the pile 10 and between the thumb piles.

The CFT pile can be constructed with the upper steel pipe 100 in the case of a soil section where excavation is easy, but it may be difficult or impossible to apply the thumb pile when the rock is located in the lower part of the ground. Therefore, the CFT pile couples the upper steel pipe 100 and the lower steel pipe 200 to the lower part of the upper steel pipe 100.

The lower steel pipe 200 is applied to a case where it is difficult to insert the upper steel pipe 100 into the lower ground because the rock is located in the lower part of the ground.

The upper steel pipe 100 has an excellent proof against vertical stress by inserting the filled concrete therein and also has a strong effect on the bending stress caused by the horizontal earth pressure by suppressing the deformation of the upper steel pipe 100 by the filled concrete.

In the present invention, the lower steel pipe (200) for constituting the rock pile is located at the lower part of the upper steel pipe (100). The filled concrete of the upper steel pipe 100 passes through the lower steel pipe 200 to fill the filled concrete.

The upper portion of the lower steel pipe 200 is inserted into the lower portion of the lower steel pipe 100 and is coupled.

The upper steel pipe 100 of the embodiment of the present invention is composed of an upper steel pipe body 101 having an upper end and a lower end opened in a cylindrical shape of a hollow space 102 in which the hollow is hollow.

A plurality of thread grooves 114 are formed in the circumferential direction on the inner surface of the lower end of the upper steel pipe body 101. The upper portion of the thread groove 114 forms a protruding surface 112 having a constant inclination, A plurality of engaging grooves 110 having a certain depth in the circumferential direction are formed.

The protruding surface 112 is formed in a tapered structure so as to become narrower from the bottom to the top.

The lower steel pipe 200 of the embodiment of the present invention includes a lower steel pipe body 201, a fastening member 210, a rotating member 300, and a connecting member 400.

The lower steel pipe 200 is composed of a cylindrical lower steel pipe body 201 and has an open upper end. The upper part of the lower steel pipe body 201 is formed with a fastening member 210 formed to be smaller than the diameter of the upper steel pipe body 101.

The fastening member 210 has a hollow cylindrical shape and a plurality of threads 212 corresponding to the thread groove 114 are formed on an outer circumferential surface of the fastening member 210. The fastening member 210 is spaced a predetermined distance above the thread 212, 110 are formed on the outer circumferential surface of the engaging portion.

The stopping jaw 214 protrudes in the form of a ring along the outer peripheral surface of the fastening member 210 and is made of a material having elasticity while supporting the strength of the fastening force.

The lower steel pipe body 201 has a hollow cylindrical shape extending from the fastening member 210 on the upper surface thereof, and a truncated conical rotating member 300 is formed on the lower surface thereof.

When the fastening member 210 of the lower steel pipe 200 is inserted into the lower inner side of the upper steel pipe 100, the upper steel pipe 100 is rotated and the thread 212 of the lower steel pipe body 201 is inserted into the upper steel pipe body And the engaging protrusion 214 of the fastening member 210 is inserted into the threaded groove 114 of the fastening member 101 with interference so as to contact the protruding face 112 of the upper steel pipe body 101, (214) is engaged with the engaging groove (110) of the lower steel pipe body (201) in a concave convex manner. This fastening method can firmly couple the upper steel pipe 100 and the lower steel pipe 200 while easily fastening them.

The rotary member 300 extends from the lower surface of the lower steel pipe body 201 and is formed in a frustum shape and includes a first conical portion 310, a second conical portion 320, a third conical portion 330, In the order of decreasing diameter.

The first conical portion 310 has a plurality of discharge ports along the side edge of the body, and excavated material (ground, stone, etc.) is discharged to the outside when excavated.

The second conical portion 320 and the third conical portion 330 may be formed by cutting the outer surface of the body in a gear forming manner to form the helical projections 321 and 331 or attach or combine the helical projections 321 and 331 Respectively.

The spiral protrusions 321 and 331 may be formed to be inclined at a predetermined angle in the downward direction and may be formed at regular intervals with the adjacent other spiral protrusions 321 and 331 or may have a wider spacing from the lower part to the upper part.

When the lower steel pipe 200 is inserted into the rock bottom at the lower part of the ground, the lower steel pipe body 201 is rotated to excavate along the spiral protrusions 321 and 331 of the second and third cone parts 330 and 330 The water is excavated and easily inserted into the bottom of the ground and firmly connected.

The first cone part 310, the second cone part 320 and the third cone part 330 can be detachably coupled to each other. When the abrasion of the first cone part 310, the third cone part 320, The life can be extended.

5, the rotating member 300 according to another embodiment of the present invention is the same as the first and second conical parts 310 and 320 described above, The plurality of concave and convex portions 341 are radially coupled to the outer circumferential surface of the third conical portion at regular intervals in a row and a row without being constituted by the concave portions 321 and 331. The plurality of concave-convex portions 341 are spaced apart from each other in rows and columns, and a space is formed between the concave-convex portions 341, thereby increasing frictional force during excavation.

The connecting member 400 is vertically coupled to the outer circumferential surface of the lower steel pipe body 201 inserted in the rock layer in a rod shape.

The configuration of the connecting member 400 will be described in detail with reference to FIGS. 6 and 7. FIG.

FIG. 6 is a view showing a configuration of a connecting member according to the first and second embodiments of the present invention, and FIG. 7 is a view showing a configuration of a connecting member according to the third embodiment of the present invention.

6A, the connecting member 400 of the first embodiment of the present invention has a longitudinal inner groove 412 formed inside a lower steel pipe body 201, A first spring support base 421, a second spring support base 431 and a third spring support base 441 are formed at regular intervals in upper, middle, and lower portions of the first spring support base 421, A first spring member 420, a second spring member 430 and a third spring member 440 are coupled to the second spring support 431 and the third spring support 441, The spring member 420, the second spring member 430 and the third spring member 440 are coupled to the rear surface of the bar-shaped connecting member body 410.

The connection member body 410 can be finely moved by the elastic force of the first spring member 420, the second spring member 430, and the third spring member 440.

The connecting member body 410 has through holes 411 formed at regular intervals and facilitates the attachment of the mounting members of the earth retaining structure through the through holes 411 or the installation of the reinforcing steel such as the reinforcing bars 500 for grids Thereby facilitating the operation.

6B, the connecting member 400 of the second embodiment of the present invention includes a connecting member body 410 having a plurality of through holes 411 formed therein, And an elastic member 450 is formed at the upper, middle, and lower points of the inner surface of the lower steel pipe body 201.

The elastic member 450 includes a female screw groove 452 formed in the inner surface 451 of the lower steel pipe body 201 and a screw bolt 453 coupled to the female screw groove 452. The screw bolt 453 And a support 455 having one end coupled to the spring 454 and the other end coupled to one surface of the coupling member body 410. The spring 454 is coupled to one side of the coupling member body 410, The elastic member 450 functions to finely adjust the elasticity of the connecting member body 410 even when the connecting member body 410 is moved by an external force.

7, the connecting member 400 of the third embodiment of the present invention has a longitudinal inner groove 412 formed inside a lower steel pipe body 201, A second spring support 431 and a third spring support 441 are formed at regular intervals in upper, middle, and lower portions of the first spring support 421, the second spring support 421, The first spring member 420, the second spring member 430 and the third spring member 440 are coupled to the spring support 431 and the third spring support 441, respectively.

The rod-shaped connecting member body 410 is divided into upper and lower parts about a rotation bracket 460 which can be adjusted in angle at an intermediate point.

The second spring member 430 is coupled to one side of the rotation bracket 460 and the first spring member 420 and the third spring member 440 are coupled to the upper connecting member body 410, And are coupled to one side of the connecting member body 410, respectively.

The connecting member 400 is rotated by the rotation bracket 460 and the spring members 420, 430, and 440 in order to adjust the position of the connecting member 400 according to the surrounding topography when the external reinforcing force of the reinforcing bar 500 It is possible to adjust the position finely, thereby facilitating the installation work.

FIG. 8 is a view illustrating a lattice reinforcement installed between CFT piles for installing the earth retaining structure according to an embodiment of the present invention. FIG. 9 is a cross- Fig. 5 is a view showing a shotcrete poured after reinforcing bars are installed.

8 and 9, a reinforcing bar 500 for lattice is installed between the CFT piles (the upper steel pipe 100 and the lower steel pipe 200), and the shotcrete 510 is laid on the rock excavation surface Build up the earth retaining structure.

The connecting member 400 is installed with a grid reinforcing bar 500 with a clearance equal to the distance of the through holes 411 formed in the vertical direction, and corrects the installation error according to excavation conditions.

In the case of constructing the earth retaining structure by placing the shotcrete 510 on the rock excavation surface, the installation work of the grid-like reinforcing bars 500 to be embedded in the shotcrete 510 is carried out in order to reinforce the bending stiffness of the shotcrete 510, The installed connecting member 400 facilitates the installation work of reinforcing steel including the grid-shaped reinforcing bars 500.

The method of constructing the CIP earth retaining wall according to the embodiment of the present invention is characterized in that the thumb piles 100 and 200 are installed such that the tip portions are inserted to a certain depth of the rock layer at regular intervals, (100) and the thumb piles (100, 200) are installed between the thumb piles (100, 200) and the thumb piles (100, 200) Exposing the connecting member 400 attached to the thumb piles 100 and 200 by excavating the entire surface of the continuous earth continuous wall 100 and exposing the connecting member 400 attached to the thumb piles 100 and 200 using the connecting member 400, And installing the earth retaining structure on the rock excavation surface between the thumb piles 100 and 200.

Next, a grid-like reinforcing bar 500 is installed between the connecting member 400 and the connecting member 400, and the shotcrete 510 is installed so that the grid-like reinforcing bars 500 are embedded.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, It belongs to the scope of right.

10: in-situ pile 20:
100: upper steel pipe 101: upper steel pipe body
102: space portion 110:
112: projecting surface 114: screw groove
200: lower steel pipe 201: lower steel pipe body
210: fastening member 212: threaded
214: locking jaw 300: rotating member
310: first cone 312: outlet
320: second conical portion 321: helical projection
330, 340: third conical portion 331: helical projection
341: concave / convex portion 400: connecting member
410: connecting member body 411: through hole
412: inner groove 420: first spring member
421: first spring support member 430: second spring member
431: second spring support member 440: third spring member
441: third spring support 450: elastic member
451: inner surface 452: female thread groove
453: screw bolt 454: spring
455: Support base 460: Rotation bracket
500: grid-shaped reinforcing bars 510: shotcrete

Claims (5)

And a pile of a thumb which is arranged at a predetermined distance between the pile and the pile, and which is installed at a depth deeper than the pile of the pile,
Wherein the thumb pile has a cylindrical shape hollowed out so that the filled concrete is poured therein, a plurality of screw grooves formed in the circumferential direction on the lower end inner side surface thereof, and a tapered structure An upper steel pipe forming a protruding surface and having a plurality of engaging grooves formed at a predetermined depth in a circumferential direction on an upper surface of the protruding surface;
A plurality of threads corresponding to the thread grooves are formed on an outer circumferential surface of the threaded portion and formed in a ring shape so as to be inserted into the engaging groove on an upper portion of the threaded portion, And a lower steel pipe comprising a lower steel pipe body formed of a plurality of engaging jaws made of a material and formed in a cylindrical shape hollowed out from the fastening member and having a truncated cone-
The rotary member includes a first conical portion extending from a lower surface of the lower steel pipe body and formed in a truncated conical shape and having a plurality of exhaust ports along a side edge thereof; A second conical portion formed with a plurality of helical protrusions formed obliquely and becoming narrower from the upper portion to the lower portion, and a third conical portion coupled to the third conical portion in order of decreasing diameter,
A plurality of concave-convex portions are radially joined to the outer circumferential surface of the third conical portion at regular intervals in a row and a row, the plurality of concave-convex portions are spaced apart from each other by rows and columns, and a space is formed between the concave-convex portions, ,
The first conical portion, the second conical portion, and the third conical portion are separately detachable and replaceable,
Wherein when the fastening member of the lower steel pipe is inserted into the lower inner side of the upper steel pipe, the upper steel pipe is rotated and the thread of the lower steel pipe body is fastened to the screw groove of the upper steel pipe body, Wherein the engaging jaw is inserted into the engaging groove of the lower steel pipe body in a concave-convex manner so that the engaging jaw is engaged with the protruding face of the upper steel tube body,
Further comprising a connecting member, which is vertically formed in a bar shape and connected to the outer circumferential surface of the lower steel pipe body inserted into the rock layer and formed with through holes at regular intervals,
The connecting member includes a connecting member body having a plurality of through holes spaced apart from each other by a predetermined distance in the vertical direction and a connection member body vertically formed on the outer circumferential surface of the lower steel pipe body, An elastic member is formed at the intermediate and lower points,
The elastic member includes a female screw groove formed on an inner surface of the lower steel pipe body, a screw bolt coupled to the female screw groove, a spring coupled to one side of the screw bolt, Wherein the elastic member is capable of fine adjustment by an elastic force even when the connecting member body is moved by an external force. And a pile of a thumb which is arranged at a predetermined distance between the pile and the pile, and which is installed at a depth deeper than the pile of the pile,
Wherein the thumb pile has a cylindrical shape hollowed out so that the filled concrete is poured therein, a plurality of screw grooves formed in the circumferential direction on the lower end inner side surface thereof, and a tapered structure An upper steel pipe forming a protruding surface and having a plurality of engaging grooves formed at a predetermined depth in a circumferential direction on an upper surface of the protruding surface;
A plurality of threads corresponding to the thread grooves are formed on an outer circumferential surface of the threaded portion and formed in a ring shape so as to be inserted into the engaging groove on an upper portion of the threaded portion, And a lower steel pipe comprising a lower steel pipe body formed of a plurality of engaging jaws made of a material and formed in a cylindrical shape hollowed out from the fastening member and having a truncated cone-
The rotary member includes a first conical portion extending from a lower surface of the lower steel pipe body and formed in a truncated conical shape and having a plurality of exhaust ports along a side edge thereof; A second conical portion formed with a plurality of helical protrusions formed obliquely and becoming narrower from the upper portion to the lower portion, and a third conical portion coupled to the third conical portion in order of decreasing diameter,
A plurality of concave-convex portions are radially joined to the outer circumferential surface of the third conical portion at regular intervals in a row and a row, the plurality of concave-convex portions are spaced apart from each other by rows and columns, and a space is formed between the concave-convex portions, ,
The first conical portion, the second conical portion, and the third conical portion are separately detachable and replaceable,
Wherein when the fastening member of the lower steel pipe is inserted into the lower inner side of the upper steel pipe, the upper steel pipe is rotated and the thread of the lower steel pipe body is fastened to the screw groove of the upper steel pipe body, Wherein the engaging jaw is inserted into the engaging groove of the lower steel pipe body in a concave-convex manner so that the engaging jaw is engaged with the protruding face of the upper steel tube body,
Further comprising a connecting member, which is vertically formed in a bar shape and connected to the outer circumferential surface of the lower steel pipe body inserted into the rock layer and formed with through holes at regular intervals,
Wherein the connecting member includes a connecting member body having a plurality of through holes spaced apart from each other by a predetermined distance in the vertical direction and a connecting member body vertically formed on an outer circumferential surface of the lower steel pipe body,
The connecting member has a longitudinal inner groove formed inside the lower steel pipe body, and a first spring support, a second spring support, and a third spring support are formed on one surface of the inner groove at regular intervals A first spring member, a second spring member, and a third spring member are coupled to the first spring support, the second spring support, and the third spring support, respectively,
The rod-shaped connecting member body is divided into upper and lower parts by a rotation bracket capable of adjusting an angle at an intermediate point,
The first spring member and the third spring member are respectively coupled to one side of the upper connecting member body and the lower connecting member body, respectively, and the second spring member is coupled to one side of the rotating bracket,
The connecting member may be provided on the rotation bracket, the first spring member, the second spring member, the third spring member, and the third spring member, Wherein the micro-position adjustment is possible. delete In the construction method of the earth retaining wall,
Providing a thumb pile so that the tip portion is inserted up to a certain depth of the rock layer at regular intervals and making the connecting member attached to the thumb pile face the excavation surface;
Establishing a continuous thermal underground continuous wall by providing a pile between the thumb pile and the thumb pile;
Exposing a connecting member attached to the thumb pile by excavating a front surface of the continuous earth continuous wall; And
And constructing the earth retaining structure on the rock excavation surface between the thumb pile and the thumb pile using the connecting member,
Wherein the thumb pile has a cylindrical shape hollowed out so that the filled concrete is poured therein, a plurality of screw grooves formed in the circumferential direction on the lower end inner side surface thereof, and a tapered structure An upper steel pipe forming a protruding surface and having a plurality of engaging grooves formed at a predetermined depth in a circumferential direction on an upper surface of the protruding surface;
A plurality of threads corresponding to the thread grooves are formed on an outer circumferential surface of the threaded portion and formed in a ring shape so as to be inserted into the engaging groove on an upper portion of the threaded portion, And a lower steel pipe comprising a lower steel pipe body formed of a plurality of engaging jaws made of a material and formed in a cylindrical shape hollowed out from the fastening member and having a truncated cone-
The rotary member includes a first conical portion extending from a lower surface of the lower steel pipe body and formed in a truncated conical shape and having a plurality of exhaust ports along a side edge thereof; A second conical portion formed with a plurality of helical protrusions formed obliquely and becoming narrower from the upper portion to the lower portion, and a third conical portion coupled to the third conical portion in order of decreasing diameter,
A plurality of concave-convex portions are radially joined to the outer circumferential surface of the third conical portion at regular intervals in a row and a row, the plurality of concave-convex portions are spaced apart from each other by rows and columns, and a space is formed between the concave-convex portions, ,
The first conical portion, the second conical portion, and the third conical portion are separately detachable and replaceable,
Wherein when the fastening member of the lower steel pipe is inserted into the lower inner side of the upper steel pipe, the upper steel pipe is rotated and the thread of the lower steel pipe body is fastened to the screw groove of the upper steel pipe body, Wherein the engaging jaw is inserted into the engaging groove of the lower steel pipe body in a concave-convex manner so that the engaging jaw is engaged with the protruding face of the upper steel tube body,
Further comprising a connecting member, which is vertically formed in a bar shape and connected to the outer circumferential surface of the lower steel pipe body inserted into the rock layer and formed with through holes at regular intervals,
The connecting member includes a connecting member body having a plurality of through holes spaced apart from each other by a predetermined distance in the vertical direction and a connection member body vertically formed on the outer circumferential surface of the lower steel pipe body, An elastic member is formed at the intermediate and lower points,
The elastic member includes a female screw groove formed on an inner surface of the lower steel pipe body, a screw bolt coupled to the female screw groove, a spring coupled to one side of the screw bolt, Wherein the elastic member is capable of fine adjustment by an elastic force even when the connecting member body is moved by an external force. 5. The method of claim 4,
In the step of constructing the earth retaining structure,
Providing a grid-like reinforcing bar between the connecting member and the connecting member, and installing a shotcrete to fill the grid-like reinforcing bars.

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