Method for constructing a chair-type, self-supported earth retaining wall

Abstract

The present invention provides a method for constructing a chair-type, self-supported earth retaining wall used for retaining external forces such as earth pressure prior to an excavation. The method of the present invention forms a first column of piles having a plurality of piles arranged along the circumference of the region to be excavated. Subsequently, the method comprises forming a second column of piles having a plurality of piles by consecutively perforating a plurality of holes by a predetermined spacing at predetermined positions outwardly from the first column of piles, along the circumference of the region to be excavated, inserting H-beams into the respective holes, filling left and right spaces of the webs of the H-beams with soil, and filling the outer spaces of the flanges of the H-beams with a flowable stiffening material. The method subsequently comprises interconnecting the first column of piles and the second column of piles by a connection member. The first column of piles and the second column of piles are formed along the circumference of the region to be excavated, with an outward spacing, and connected to each other by the connection member.The present invention provides a method for constructing a chair-type, self-supported earth retaining wall used for supporting external forces such as earth pressure prior to an excavation. The method of the present invention comprises forming a first pile array 20 having a plurality of piles 22 arranged along a circumference of an region to be excavated. Subsequently, the method comprises forming a second pile array 30 having a plurality of piles arranged along a circumference of the to-be-excavated region by consecutively drilling a plurality of boreholes 31 at predetermined intervals at predetermined positions outwardly spaced apart from the first pile array, inserting H-beams into the respective boreholes, filling left and right spaces of webs 34 of the H-beams 32 with soil 40, and filling the outer spaces of flanges 36 of the H-beams with a flowable hardening material 50. The method subsequently comprises fixedly interconnecting the first pile array and the second pile array using a connection member. The first pile array and the second pile array are formed in such a fashion as to be outwardly spaced apart from each other along the circumferences of the to-be-excavated region, and are connected to each other by the connection member to construct an underground earth retaining wall.

Description

TECHNICAL FIELD[0001]The present invention relate to a method for constructing a chair-type, self-supported earth retaining wall, and particularly to, such a method for constructing a chair-type, self-supported earth retaining wall, in which an earth retaining wall used for supporting an external force such as earth pressure or the like prior to an excavation can be constructed by a supporting construction technique employing an improved double-row pile structure so as to complement various shortcomings involved in a conventional temporary facility construction technique such as a strut supporting construction technique, an earth anchor construction technique or the like.BACKGROUND ART[0002]In general, when filling the ground, cutting the ground, or drilling the ground, and the like are performed, while a slope surface is generally formed to maintain the stability of the ground. However, when the excavation is performed to improve the utility of the land more effectively or to impro...

AI Technical Summary

Benefits of technology

[0021]The method for constructing a chair-type, self-supported earth retaining wall of the present invention can improve several disadvantages involved in an existing temporary facility construction technique such as the strut supporting construction technique, the earth anchor construction technique, or the like. That is, according to the present invention, the necessity of using struts is eliminated, so that the quantity of the steel sheets used is reduced, thereby saving the construction expense, shortening the construction period, making the construction of heavy equipment in the excavation site smooth, and facilitating a subsequent mold work to improve the construction capacity. In addition, since the present invention implements a self-supported temporary facility structure to resolve a problem of an encroachment into adjacent private lands occurring when the anchor is installed on the ground, the restriction in the downtown area construction work, etc., is mostly removed as compared to the earth anchor construction technique. Moreover, the present invention can further reduce land settlement and displacement caused by the temporary facility construction work thereby minimizing a damage of adjacent structure due to earth excavation and further increasing the excavatable depth as compared to the self-supported earth retaining construction method that has been proposed by the present inventor in PCT international publication No. WO 2007 / 117050 entitled “UNDERGROUND RETAINING WALL FOR PUBLIC WORKS AND METHOD FOR CONSTRUCTING THE SAME”. In particular, the flowable hardening material such as cement paste is charged into the outer spaces of both flanges of the H-beam, soil such on-site soil is poured into the inner spaces of the both flanges of the H-beam to support the H-beam in the boreholes. Thus, the H-beam is discarded into the ground in case of an existing traditional construction method, but the reuse of the H-beam is facilitated and the displacement the H-beam occurring in the boreholes can be effectively prevented in case of a novel construction method. Accordingly, since the stable support of the H-beams within the boreholes minimizes the occurrence of the displacement of the earth retaining wall, the merit of the self-supported earth retaining wall employing a double-row pile structure can be maximized. In addition, since the present invention uses various walls such as cast-in-place piles (CIPs), soil cement walls (SCWs), sheet piles, and the like as the first pile array, it enables the inventive earth retaining wall to bind to various kinds of walls to provide a water stopping function and exhibit a heaving prevention effect, thereby ensuring its excellent usability. Moreover, the chair-type, self-supported earth retaining wall construction method according to the present invention can be utilized complementarily together with the existing traditional earth retaining construction method. In case of this construction, the conventional construction method can show the effect of the present invention and simultaneously can further increase the underground excavation depth. If the present invention is used together with the strut supporting construction method as a complementary supporting construction method, the construction distance and use quantity of the struts is reduced, thereby improving the construction capacity and the economic efficiency. In addition, if the present invention is used together with the earth anchor construction method as a complementary supporting construction method, the construction distance and use quantity of the earth anchors is reduced, thereby improving the construction capacity and the economic efficiency.

Problems solved by technology

Accordingly, in case of a large drilling work, the use of a large quantity of steel sheets greatly increases the construction expense, and the arranged struts obstruct the field works such as the movement of the drilling equipment, the conveyance of the drilled earth and sand, and the construction materials, and the like.

In addition, the above strut supporting construction technique causes impediments to works of the reinforcing steel bar of a structure or a mold, thereby reducing the working efficiency.

Also, in the strut supporting construction technique, a number of through-holes produced in the structure causes problems of durability and waterproof property of an completed underground structure.

However, this construction technique has serious disadvantages in that there is a restriction in the conditions for the construction field in case of downtown area construction work because it could encroach adjoining private lands, and the construction expense becomes high in case of non-large sized drilling works.

However, in case of a ground having a high underground water level and a ground having a subsidence property, there is a risk of slope breakage, and the modification of the inclined surface due to cutting off of the earth is serious, thereby causing the sinking of the adjoining ground.

Further, the above soil nailing construction technique has a disadvantage in that it is difficult to apply to the ground of specific conditions, and it requires a careful attention.

However, there occur problems in that stability of the inclined surface is difficult to secure in a weak ground, it is improper for a deep drilling work, a space is narrow and the workability is poor at the time of constructing a structure in the raker.

However, the above construction technique has disadvantages in that since the steel wire is disposed linearly, and a moment produced in the girth due to the soil pressure is different from a resistance moment produced by prestressing, so that an unbalanced moment always acts on in the members, and the girth is weak to a local unbalanced load when the length thereof is made long.

In addition, such a construction technique has a limitation in extending the length of the prestressed girth because of restriction in increasing eccentricity due to limitation in the rigidity of the installation device.

However, there frequently occurs the case where a pile driving work is not performed smoothly because of gravel existing in soil or other ground conditions.

In particular, the H-beams are inserted into the ground by a ground boring method employing Augering instead of the pile driving in most fields due to a driving noise generated during the pile driving.

However, this filling work cannot be performed well due to a relatively deep boring depth as compared to a small clearance space because the boring depth of the borehole 500 is more than 10 m. In addition, although the filling work is performed well, soil must be well tamped down in order to achieve an expected and desired effect.

However, in this tamping work, it is difficult to expect the desired effect at the regions beyond a region within a range of 1 m on the ground surface.

However, such a method of employing the cement paste 540 entails problems in that it makes difficult a pullout work for collecting the inserted H-beam 520 after the completion of the construction, and hardened cement lumps surrounding the surface of the H-beam 520 must be removed for the reuse of the H-beam although the inserted H-beam 520 is collected.

Accordingly, such a cement paste injection method involves a drawback in that it is difficult to apply to the construction in which the H-beam must be substantially recollected.

In particular, in the case where the H-beam is constructed in a self-supported earth retaining construction method, the filling work-associated problem is very important.

However, as mentioned above, the earth retaining construction method encounters many drawbacks in terms of construction.

In most self-supported earth retaining construction in which the H-beams must be collected, an incomplete borehole filling work causes great displacement of the self-supported earth retaining wall, which contributes to a reduction in self-supporting capability.

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