WO2007133001A1

WO2007133001A1 - Construction method of breast wall for tree planting

Info

Publication number: WO2007133001A1
Application number: PCT/KR2007/002270
Authority: WO
Inventors: Dong-Soo Seo; Kwang-Ho Kim
Original assignee: Dong-Soo Seo; Kwang-Ho Kim
Priority date: 2006-05-11
Filing date: 2007-05-09
Publication date: 2007-11-22
Also published as: KR100679873B1

Abstract

Disclosed is a construction method of a breast wall for tree planting. The tree planting breast wall entails no risk of collapse and inhibits damage because the reinforcements are not exposed outside, makes construction thereof simple because wrapping is very easy, provides very excellent tree planting capability after the construction, and is very suitable for eco-friendly con¬ struction for preventing the earth from being swept away in a river area and in an area of flowing water because it can maintain the structural functionality and strength thereof for a long time without using concrete or reinforcing bars.

Description

CONSTRUCTION METHOD OF BREAST WALL FOR TREE

PLANTING

Technical Field

[1] The present invention relates, in general, to a construction method of a breast wall for tree planting, and more particularly, to a construction method of a breast wall for tree planting , in which the tree planting breast wall eliminates the fear of collapse, inhibits damage because reinforcements are not exposed outside, makes construction thereof simple due to very easy wrapping thereof, provides excellent tree planting capability after construction, and is very suitable for eco-friendly construction for preventing the earth from being swept away in a river area and in an area of flowing water because it can maintain the structural functionality and strength thereof for a long time without using concrete or reinforcing bars. Background Art

[2] An earth reinforcement method functions to form a new complex structure by installing at least one reinforcement, having the shape of a strip or a plate having great tensile force, in a layer of filled earth, employing earth as a main component since ancient times, at regular intervals or in a desired place and burying the installed reinforcement with backfilled earth, and is widely used for mechanically stabilizing earth structures using earth.

[3] Examples of the construction using this earth reinforcement method include a mechanically stabilized earth wall (MSEW) for building a vertical wall structure, and a reinforced steep slope or reinforced soil slope (RSS). A face batter for constructing the MSEW, which functions like a retaining wall, ranges from about 80° to about 90° depending on the location thereof, and the RSS is built to have a face batter of 70° or less, depending on the face batter design.

[4] In order to maintain the original angle of the vertical wall structure when the

MSEW is constructed and the face batter when the RSS is constructed, leading frames or batter boards are installed before and during the construction of the foundation.

[5] The batter boards are used for measuring the angle according to the construction of the earth layer, are initially installed at the site at a point running from a smooth slope to a steep slope, and are installed on the basis of the height of the front side of the earth layer in the state in which the earth layer is continuously constructed.

[6] Meanwhile, in order to form the earth layer accompanied by the construction of the vertical wall structure or the earth slope, in the state in which a guide frame is installed in front of the vertical wall structure or the earth slope from a construction position using materials such as wood or wire mesh and reinforcing bars, and in which reinforcement capable of resisting a mass of earth is installed, earth work (filling and compaction) is performed behind the guide frame.

[7] In order to form the earth layer, the batter boards are installed in an area designed as foundation ground, and the guide frame is installed on filled earth ground on the basis of the batter boards. Further, the guide frame is used to arrange reinforcing bars in a lattice pattern, or to make a frame using wood, and is formed to have the same face batter as the batter boards. The guide frame is installed at a starting point of the earth slope and is constructed in a transverse direction.

[8] The reinforcement is installed on the ground on which the guide frame is placed.

When the reinforcement, the geogrid or geotextile, is installed on the earth layer or is totally wrapped, the earth is filled and compacted behind the guide frame in the state in which part of the reinforcement is put aside at the upper portion of the guide frame, and the reinforcement that has been put aside is arranged toward the upper portion of the earth mass, i.e. toward the front of the guide frame. The earth work is performed on the reinforcement with the earth at a predetermined amount (at a height of about 8 cm to about 15 cm), thereby forming the earth layer.

[9] In the state in which the earth layer is formed, other guide frames and reinforcement are installed on the earth layer. A mass of earth having a face batter or a slope is continuously reinforced by the repetition of the earth work described above.

[10] In the construction of the reinforced earth mass, which is continuously performed by the above-described method, other separate batter boards having a predetermined length are bound at a predetermined vertical position of the reinforced earth mass so as to have the same direction as the slope. The angle of construction is measured at the sight of the batter boards. In this way, the construction is performed.

[11] Afterwards, the earth work is performed by installing the guide frame and reinforcement as described above. Thereby, construction can be completed.

[12] Meanwhile, the batter boards for the vertical wall structure for constructing a separate-type MSEW are installed perpendicular to the front face of the earth layer, and the guide frame, made of vertically arranged reinforcing bars, is installed. Thereby, the wall structure perpendicular to the ground can be realized through the reinforcement and the earth work as described above.

[13] However, this conventional tree planting breast wall has a problem in that, when the reinforcement is exposed outside and is damaged on the outside by a fire or a sharp tool such as a knife, the breast wall structure itself is in serious danger of collapsing.

[14] Further, a block- type tree planting breast wall can support the transverse earth pressure to some degree, but is difficult to wrap. Thus, the block-type tree planting breast wall makes use of a steel mesh, thereby sharply reducing the tree planting capability.

Disclosure of Invention

Technical Problem

[15] Accordingly, the present invention has been made keeping in mind the above problems occurring in the related art, and an object of the present invention is to provide a construction method of a breast wall for tree planting, in which the tree planting breast wall is in no danger of collapsing and inhibits damage because reinforcements are not exposed outside, makes construction thereof simple because wrapping is very easy, provides very excellent tree planting capability after the construction, and is very suitable for eco-friendly construction for preventing the earth from being swept away in a river area and in an area of flowing water because it can maintain the structural functionality and strength thereof for a long time without using concrete and reinforcing bars. Technical Solution

[16] According to an aspect of the present invention, there is provided a construction method of a breast wall for tree planting, the method comprising the steps of:

[17] installing a geogrid of synthetic resin at a construction site;

[18] stacking tree planting packs or jute bags at a front lower portion of the geogrid, bending the geogrid in a vertical upward direction, and placing the bent geogrid on a top one of the tree planting packs or jute bags;

[19] disposing a molded frame, upper and lower ends of which are open, on the geogrid so as to be in surface contact with the tree planting packs or jute bags, setting an earth sack, an upper end of which is open, in the molded frame, and filling and compacting earth in the earth sack;

[20] removing the molded frame from the earth sack, and primarily placing and compacting a first earth layer, adjacent to the rear of the earth sack, at a half height of the earth sack;

[21] bending back the geogrid at the front of the geogrid, making one end of the geogrid extend backwards to wrap the earth sack, fastening the tree planting packs or jute bags with the geogrid, and secondarily placing and compacting a second earth layer up to the top of the earth sack behind the earth sack; and

[22] placing the geogrid on the top of the second earth layer again, stacking new tree planting packs or jute bags on the lower top tree planting pack or jute bag, setting the molded frame and the earth sack at a position slightly displaced backward from the top of the lower earth sack, and sequentially repeating the previous steps up to the desired height of the tree planting breast wall.

[23] According to an aspect of the present invention, there is provided a construction method of a breast wall for tree planting, the method comprising the steps of:

[24] installing a geogrid of synthetic resin at a construction site;

[25] stacking tree planting packs or jute bags at a front lower portion of the geogrid, bending the geogrid in a vertical upward direction, and placing the bent geogrid on a top one of the tree planting packs or jute bags;

[26] primarily placing and compacting a first earth layer to a half height of the earth sack;

[27] bending back the geogrid at the front of the geogrid, making one end of the geogrid extend backwards to wrap the first earth layer, fastening the tree planting packs or jute bags with the geogrid, and secondarily placing and compacting a second earth layer up to the top tree planting pack or jute bag behind the geogrid; and

[28] placing the geogrid on the top of the second earth layer again, stacking new tree planting packs or jute bags on the lower top tree planting pack or jute bag, setting the tree planting packs or jute bags to a position slightly displaced backward from the Io wer top tree planting pack or jute bag, and sequentially repeating the previous steps up to the desired height of the tree planting breast wall.

[29] Hereinafter, an exemplary embodiment according to the invention will be described in detail with reference to the accompanying drawings.

[30] For reference, when the detailed descriptions of known functions and constructions are determined to make the subject matter of the invention needlessly obscure, they will be avoided hereinafter.

[31] Further, technical terms, as will be described below, are defined in consideration of their function in the present invention, which may be varied according to the intention of user or operator or the usual practice.

[32] Therefore, it is apparent that such terms should be defined based on the contents of this specification.

[33] FIG. 1 is a perspective view illustrating a breast wall for tree planting constructed by a construction method of a breast wall for tree planting according to an embodiment of the present invention. FIG. 2 is an enlarged side sectional view illustrating the state of installing a geogrid in a construction method of a breast wall for tree planting according to an embodiment of the present invention. FIG. 3 is a side sectional view illustrating the state of disposing tree planting packs or tree planting jute bags at the front lower portion of a geogrid in a construction method of a breast wall for tree planting according to an embodiment of the present invention. FIG. 4 is a side sectional view illustrating the state of setting earth sacks in molded frames behind tree planting packs and putting earth in the earth sacks in a construction method of a breast wall for tree planting according to an embodiment of the present invention. FIG. 5 is a side sectional view illustrating the process of removing molded frames from earth sacks in a construction method of a breast wall for tree planting according to an embodiment of the present invention. FIG. 6 is a side sectional view illustrating the state in which a first-stair earth layer is completed in a construction method of a breast wall for tree planting according to an embodiment of the present invention. FIG. 7 is a side sectional view illustrating the state of stacking tree planting packs and installing a geogrid on the tree planting packs in order to form a second-stair earth layer in a construction method of a breast wall for tree planting according to an embodiment of the present invention. FIG. 8 is a side sectional view illustrating the state in which a first- stair earth layer is completed on a first-stair earth layer in a construction method of a breast wall for tree planting according to an embodiment of the present invention.

[34] The construction method of a breast wall for tree planting 1 according to an embodiment of the present invention functions to further increase tree planting capability to maintain the structure of the tree planting breast wall firmer for a longer time. In FIG. 2, i.e. in the enlarged side sectional view, illustrating the state of installing a geogrid in a construction method of a breast wall for tree planting according to an embodiment of the present invention, the geogrid 30, which is made of synthetic resin and has the shape of a lattice or a repetitive flat plane, is installed on all of the ground of a construction site, thereby increasing the action resistance in an unstable slope section, increasing frictional force through mutual bonding with earth layers 41 and 42, and uniformly distributing a load at a lower portion of the unstable slope section to prevent differential settlement of the ground.

[35] In FIG. 3, i.e. in the side sectional view, illustrating the state of disposing tree planting packs or tree planting jute bags at the front lower portion of a geogrid in a construction method of a breast wall for tree planting according to an embodiment of the present invention, the tree planting packs 50 or the tree planting jute bags are stacked at the front lower portion of the geogrid 30, and the geogrid 30 is vertically bent upwards behind the top tree planting pack 50, and is thereby surrounded with tree planting packs 50. Each tree planting pack 50 is made of synthetic fiber, such as polyester or polypropylene, or civil engineering fiber, such as glass fiber, such that plants properly germinate, and has a weight from 40 kg to 55 kg with earth 11 therein. Of course, each tree planting pack 50 allows water to enter and exit, but prevents earth particles therein from coming out. Further, each tree planting pack 50 allows the permeation of water to prevent erosion.

[36] In FIG. 4, i.e. in the side sectional view illustrating the state of setting earth sacks in molded frames behind of tree planting packs and putting earth in the earth sacks in a construction method of a breast wall for tree planting according to an embodiment of the present invention, a molded frame 20 having the shape of a quadrangular tube, a quadrangular frame, or a cylinder, upper and lower ends of which are open, is disposed on the geogrid 30 so as to be in surface contact with the tree planting packs 50 or the tree planting jute bags, and an earth sack 10 having the shape of a quadrangular tube or a cylinder, an upper end of which is open, is set in the molded frame 20. Then, the earth 11 is loaded and compacted in the earth sack 10. At this time, the molded frame 20 having the shape of the quadrangular tube or frame and the earth sack 10 having the shape of the quadrangular tube facilitate filling of the earth and installation of the geogrid. Because the tree planting packs 50, located at the front of the molded frame 20, can take the place of the earth sack 10, the earth sack 10 can be omitted. Further, the molded frame 20 or the earth sack 10 may have a cylindrical shape rather than the quadrangular shape.

[37] In FIG. 5, i.e. in the side sectional view illustrating the process of removing molded frames from earth sacks in a construction method of a breast wall for tree planting according to an embodiment of the present invention, the molded frame 20 is removed from the earth sack 10, and then an earth layer 41 is primarily placed and compacted adjacent to the rear of the earth sack 10 at a half height of the earth sack 10. Thereby, a first tier 40 using the earth layers 41 and 42 is stacked and prepared.

[38] In FIG. 6, i.e. in the side sectional view illustrating the state in which a first-stair earth layer is completed in a construction method of a breast wall for tree planting according to an embodiment of the present invention, the geogrid 30 is bent back at the leading end thereof, and thus the leading end thereof extends backwards to wrap the bottom, front and top surfaces of the earth sack 10. The tree planting packs 50 or the tree planting jute bags are fastened with the geogrid 30 using a fastening means such as a fastening clip or ring. An earth layer 42 is secondarily placed and compacted up to the top of the earth sack 10 behind the earth sack 10. Thereby, the stacking of the first tier 40 using the earth layers 41 and 42 is completed. Here, it is apparent that each earth layer for the first tier should be compacted using separate equipment for compaction.

[39] In FIG. 7, i.e. in the side sectional view illustrating the state of stacking tree planting packs and installing a geogrid on the tree planting packs in order to form a second-stair earth layer in a construction method of a breast wall for tree planting according to an embodiment of the present invention, the geogrid 30 is placed on the top of the first tier 40 again, and then new tree planting packs 50 are stacked on the top tree planting pack 50 for the first tier 40.

[40] In FIG. 8, i.e. in the side sectional view illustrating the state in which a first-stair earth layer is completed on a first-stair earth layer in a construction method of a breast wall for tree planting according to an embodiment of the present invention, the molded frame 20 and the earth sack 10 are set to a position slightly displaced backward from the top of the lower earth sack 10. Like the above-mentioned method, the geogrid 30 is folded backwards, and then earth is buried and compacted in the rear of the earth sack 10. Thereby, a second tier 40a is completed. In this method, a plurality of stairs is stacked up to the desired height of the tree planting breast wall 1, so that the tree planting breast wall 1 is completed.

[41] FIG. 9 is a perspective view illustrating a breast wall for tree planting constructed by a construction method of a breast wall for tree planting according to another embodiment of the present invention. FIG. 10 is an enlarged side sectional view illustrating the state of installing a geogrid in a construction method of a breast wall for tree planting according to another embodiment of the present invention. FIG. 11 is a side sectional view illustrating the state of disposing tree planting packs or tree planting jute bags at the front lower portion of a geogrid in a construction method of a breast wall for tree planting according to another embodiment of the present invention. FIG. 12 is a side sectional view illustrating the state of primarily filling earth behind tree planting packs or tree planting jute bags in a construction method of a breast wall for tree planting according to another embodiment of the present invention. FIG. 13 is a side sectional view illustrating the state in which a first-stair earth layer is completed in a method of constructing tree planting breast wall according to another embodiment of the present invention. FIG. 14 is a side sectional view illustrating the state of stacking tree planting packs and installing a geogrid on the tree planting packs in order to form a second-stair earth layer in a construction method of a breast wall for tree planting according to another embodiment of the present invention. FIG. 15 is a side sectional view illustrating the state in which a first-stair earth layer is completed on a first-stair earth layer in a construction method of a breast wall for tree planting according to another embodiment of the present invention.

[42] The construction method of a breast wall for tree planting according to another embodiment of the present invention functions to further increase tree planting capability at a lower cost to maintain the structure of the tree planting breast wall firm for a long time.

[43] First, as in FIG. 10, the geogrid 30, which is made of synthetic resin and has the shape of a lattice or a repetitive flat plane, is installed on all of the ground of a construction site, thereby increasing action resistance in an unstable slope section, increasing frictional force through mutual bonding with earth layers 41 and 42, and uniformly distributing a load at a lower portion of the unstable slope section to prevent differential settlement of the ground.

[44] In FIG. 11, i.e. in the side sectional view illustrating the state of disposing tree planting packs or tree planting jute bags at the front lower portion of a geogrid in a construction method of a breast wall for tree planting according to another embodiment of the present invention, the tree planting packs 50 or the tree planting jute bags are stacked at the front lower portion of the geogrid 30, and the geogrid 30 is vertically bent upwards behind the tree planting packs 50, and thereby surrounds tree planting packs 50. Each tree planting pack 50 is made of synthetic fiber, such as polyester or polypropylene, or civil engineering fiber, such as glass fiber such that plants can properly grow, and has a weight from 40 kg to 55 kg with earth 11 therein. Of course, each tree planting pack 50 allows water to enter and exit, but prevents earth particles therein from coming out. Further, each tree planting pack 50 allows the permeation of water to prevent erosion.

[45] In FIG. 12, i.e. in the side sectional view illustrating the state of primarily filling earth behind tree planting packs or tree planting jute bags in a construction method of a breast wall for tree planting according to another embodiment of the present invention, an earth layer 41 is primarily placed and compacted adjacent to the rear of the tree planting packs 50 or the tree planting jute bags at a half height of the tree planting packs 50 or the tree planting jute bags. Thereby, stacking a first tier 40 using the earth layers 41 and 42 is prepared.

[46] In FIG. 13, i.e. in the side sectional view illustrating the state in which a first-stair earth layer is completed in a construction method of a breast wall for tree planting according to another embodiment of the present invention, the geogrid 30 is bent back at the leading end thereof, and thus the leading end thereof extends backwards to wrap the bottom, front and top surfaces of the earth layer 42. The tree planting packs 50 or the tree planting jute bags are fastened with the geogrid 30 using a fastening means such as a fastening clip or ring. The earth layer 42 is secondarily placed and compacted up to the top of the tree planting packs 50 or the tree planting jute bags behind the tree planting packs 50 or the tree planting jute bags. Thereby, the stacking of the first tier 40 using the earth layers 41 and 42 is completed. Here, it is apparent that each earth layer for the first tier should be compacted using separate equipment for compaction.

[47] In FIG. 14, i.e. in the side sectional view illustrating the state of stacking tree planting packs and installing a geogrid on the tree planting packs in order to form a second-stair earth layer in a construction method of a breast wall for tree planting according to another embodiment of the present invention, the geogrid 30 is placed on the top of the first tier 40 again, and then new tree planting packs 50 are stacked on the top tree planting pack 50 for the first tier 40.

[48] In FIG. 15, i.e. in the side sectional view illustrating the state in which a first-stair earth layer is completed on a first-stair earth layer in a construction method of a breast wall for tree planting according to another embodiment of the present invention, the tree planting packs 50 or the tree planting jute bags are set to a position slightly displaced backward from the top of the lower tree planting packs 50 or the tree planting jute bags. Like the above-mentioned method, the geogrid 30 is folded backwards, and then earth is buried and compacted behind the tree planting packs 50 or the tree planting jute bags. Thereby, a second tier 40a is completed. In this method, a plurality of stairs is stacked up to the desired height of the tree planting breast wall Ia, so that the tree planting breast wall Ia is completed.

[49] This tree planting breast wall 1, constructed by the construction method of the present invention is subjected to seed spraying, irrigation, and control of inset pests, thereby more smoothly facilitating the growth of vegetation in the tree planting packs 50.

[50] Further, this tree planting breast wall Ia constructed by the construction method of the present invention can more effectively prevent the earth from being swept away in a river area and an area of flowing water because the tree planting packs 50 or the tree planting jute bags can maintain the structural functionality and strength of the breast wall for a long time without using concrete and reinforcing bars.

Advantageous Effects

[51] As described above, according to the present invention, the tree planting breast wall entails no risk of collapse and inhibits damage because the reinforcements are not exposed outside, makes the construction simple because wrapping is very easy, provides very excellent tree planting capability after construction, and is very suitable for an eco-friendly construction for preventing the earth from being swept away in a river area and an area of flowing water because it can maintain the structural functionality and strength thereof for a long time without using concrete or reinforcing bars.

[52] Although exemplary embodiments of the present invention have been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. Brief Description of the Drawings

[53] FIG. 1 is a perspective view illustrating a breast wall for tree planting constructed by a construction method of a breast wall for tree planting according to an embodiment of the present invention;

[54] FIG. 2 is an enlarged side sectional view illustrating the state of installing a geogrid in a construction method of a breast wall for tree planting according to an embodiment of the present invention;

[55] FIG. 3 is a side sectional view illustrating the state of disposing tree planting packs or tree planting jute bags at the front lower portion of a geogrid in a construction method of a breast wall for tree planting according to an embodiment of the present invention; [56] FIG. 4 is a side sectional view illustrating the state of setting earth sacks in molded frames behind tree planting packs and putting earth in the earth sacks in a construction method of a breast wall for tree planting according to an embodiment of the present invention; [57] FIG. 5 is a side sectional view illustrating the process of removing molded frames from earth sacks in a construction method of a breast wall for tree planting according to an embodiment of the present invention; [58] FIG. 6 is a side sectional view illustrating the state in which a first-stair earth layer is completed in a construction method of a breast wall for tree planting according to an embodiment of the present invention; [59] FIG. 7 is a side sectional view illustrating the state of stacking tree planting packs and installing a geogrid on the tree planting packs in order to form a second-stair earth layer in a construction method of a breast wall for tree planting according to an embodiment of the present invention; [60] FIG. 8 is a side sectional view illustrating the state in which a first-stair earth layer is completed on a first- stair earth layer in a construction method of a breast wall for tree planting according to an embodiment of the present invention; [61] FIG. 9 is a perspective view illustrating a breast wall for tree planting constructed by a construction method of a breast wall for tree planting according to another embodiment of the present invention; [62] FIG. 10 is an enlarged side sectional view illustrating the state of installing a geogrid in a construction method of a breast wall for tree planting according to another embodiment of the present invention; [63] FIG. 11 is a side sectional view illustrating the state of disposing tree planting packs or tree planting jute bags at the front lower portion of a geogrid in a construction method of a breast wall for tree planting according to another embodiment of the present invention; [64] FIG. 12 is a side sectional view illustrating the state of primarily filling earth behind tree planting packs or tree planting jute bags in a construction method of a breast wall for tree planting according to another embodiment of the present invention; [65] FIG. 13 is a side sectional view illustrating the state in which a first-stair earth layer is completed in a construction method of a breast wall for tree planting according to another embodiment of the present invention; [66] FIG. 14 is a side sectional view illustrating the state of stacking tree planting packs and installing a geogrid on the tree planting packs in order to form a second-stair earth layer in a construction method of a breast wall for tree planting according to another embodiment of the present invention; and [67] FIG. 15 is a side sectional view illustrating the state in which a first-stair earth layer is completed on a first- stair earth layer in a construction method of a breast wall for tree planting according to another embodiment of the present invention.

[68] *Description of reference characters of important parts*

[69] 1, Ia: tree planting breast wall 10: earth sack

[70] 11 : earth 20: molded frame

[71] 30: geogrid 40: first tier

[72] 41: first earth layer 42: second earth layer

[73] 40a: second tier 50: tree planting pack

Claims

[1] A construction method of a breast wall for tree planting, the method comprising the steps of: installing a geogrid of synthetic resin at a construction site; stacking tree planting packs or jute bags at a front lower portion of the geogrid, bending the geogrid in a vertical upward direction, and placing the bent geogrid on a top one of the tree planting packs or jute bags; disposing a molded frame, upper and lower ends of which are open, on the geogrid so as to be in surface contact with the tree planting packs or jute bags, setting an earth sack, an upper end of which is open, in the molded frame, and filling and compacting earth in the earth sack; removing the molded frame from the earth sack, and primarily placing and compact a first earth layer adjacent to a rear of the earth sack at a half height of the earth sack; bending back the geogrid at a front of the geogrid, making one end of the geogrid extend backwards to wrap the earth sack, fastening the tree planting packs or jute bags to the geogrid, and secondarily placing and compacting a second earth layer up to a top of the earth sack behind the earth sack; and placing the geogrid on the top of the second earth layer again, stacking new tree planting packs or jute bags on the lower top tree planting pack or jute bag, setting the molded frame and the earth sack at a position slightly displaced backward from the top of the lower earth sack, and sequentially repeating the previous steps up to a desired height of the tree planting breast wall.

[2] The construction method according to claim 1, wherein the molded frame has a shape of a quadrangular tube, a quadrangular frame, or a cylinder, and the earth sack wrapped by the molded frame has a shape of a quadrangular tube or a cylinder.