JP7538577B2 - Earth retaining wall - Google Patents

Description

The present invention relates to retaining walls at construction sites.

Generally, when constructing a building, excavation work is carried out to excavate the site to a specified depth, and retaining earth is always required to carry out this excavation work. Since excavation work often involves dangers such as collapse of the surrounding ground and outflow of soil and water from the surrounding ground, retaining earth is essential work to protect the sides of the excavation to protect them. When retaining earth is required, it is necessary to decide on the construction method after thoroughly considering the soil quality at the construction site, the groundwater level, surrounding buildings, and the load on the ground.

The following construction methods have been known for earth retaining works. The most common construction method is the parent pile and horizontal sheet pile method. This parent pile and horizontal sheet pile method is known to involve first burying H-shaped steel parent piles in the ground in a straight line at the same specified intervals, and then manually fitting multiple horizontal sheet piles between the H-shaped steel without any gaps (see Patent Document 1).

JP 2016-204834 A JP 2008-208599 A

However, the technology disclosed in the above-mentioned Patent Document 1 involves embedding multiple H-shaped steel beams and fitting multiple cross-sheet piles between the H-shaped steel beams, which requires excavating the site to a specified depth, resulting in large-scale excavation work and the problem that the preparation stage for fitting multiple cross-sheet piles between the H-shaped steel beams without gaps takes a lot of time and effort.

Another problem is that excavation must be done to a specified depth, making it unsuitable for locations with poor geology, weak foundations, or excessive soil pressure. For example, if the site is near a river, water will flow out as the site is excavated, making work difficult.

Furthermore, the skills required to manually fit multiple cross-sheet piles between the H-shaped steel beams without leaving any gaps are becoming scarce, and there are fewer skilled sheet-pile craftsmen, which means work is not progressing as smoothly as expected. In addition, it is becoming difficult to obtain timber suitable for cross-sheet piles, and the larger the construction site, the greater the number of sheet piles required, making it even more difficult to obtain cross-sheet piles.

Furthermore, Patent Document 2 and other documents disclose the use of cement as an earth retaining wall, but in this case, a large amount of cement is used, which increases costs and construction time. The objective of the present invention is to provide an earth retaining wall construction method, an earth retaining wall, and an excavation guide device that can easily form an earth retaining wall regardless of the geology of the site and without deep excavation of the site.

Therefore, the inventors have conducted intensive research to solve the above problems, and as a result, the invention of claim 1 is a retaining wall in the form of a closed enclosure wall, comprising: an earth retaining construction area formed of straight portions along the X-direction and the Y-direction and a plurality of corner portions; parent piles arranged along the X-direction and the Y-direction and having H-shaped steel; a cylindrical side wall formed of cement milk; and an intermediate wall formed of the cement milk and partially intersecting with the side wall,
The above-mentioned problem has been solved by providing an earth-retaining wall characterized in that the flanges on one side of the H-shaped steel of the parent pile in the straight portion are arranged along the X and Y directions of the retaining construction area, facing the inside of the earth-retaining construction area, and are arranged so that the inner flanges are aligned in a straight line along the X and Y directions, the H-shaped steel of the parent pile is formed as a concrete support part with cement milk from the lower end to the middle of the depth, the depths of the side walls and the intermediate wall are set shallower than the depth of the parent pile, the lower part of the side wall intersects with the upper part of the concrete support part of the parent pile, and part of the side wall is contained in the gap between the two flanges of the H-shaped steel.

The above problem is solved by the invention of claim 2, which is the retaining wall described in claim 1, characterized in that the intermediate wall is made up of two pieces. The above problem is solved by the invention of claim 3, which is the retaining wall characterized in that the intermediate wall is made up of one piece.

In the invention of claim 1, the retaining wall comprises, in a straight portion of the retaining construction area, parent piles having H-shaped steel, cylindrical side walls formed of cement milk, and intermediate walls that partially intersect with the side walls formed of the cement milk. The flanges on one side of the H-shaped steel of the parent piles arranged along the X and Y directions of the retaining construction area face the inner side of the retaining construction area and are arranged so that the inner flanges are aligned in a straight line along the X and Y directions, the H-shaped steel has a concrete support portion formed by cement milk up to the middle of the depth in the vertical direction of the parent pile, the depth of the side walls and the intermediate walls are set shallower than the depth of the parent pile, and the lower side of the side wall intersects with the upper part of the concrete support portion of the parent pile.

In this configuration, the parent pile has an H-shaped steel, and the lower part of the H-shaped steel is firmly supported by the concrete support part. This concrete support part and the lower part of the side wall are configured to intersect in the vertical direction, and a part of the side wall is placed between the flanges of the H-shaped steel, so that the side wall is firmly supported by the parent pile. The H-shaped steel is formed with a strong concrete support part by cement milk from the lower end to the middle of the depth of the parent pile, and the depth of the side wall is set shallower than the depth of the parent pile, so that the amount of cement milk used is reduced, which not only reduces construction costs but also contributes to environmental conservation. In the invention of claim 2, in the retaining wall described in claim 1, the intermediate wall is formed in two pieces, so that the outer diameter of the cylindrical intermediate wall can be reduced, and the effective area of the retaining construction area can be increased. In the invention of claim 3, the intermediate wall is formed in one piece, so that the construction cost can be reduced with a simpler configuration.

1A is an oblique view of a key portion of a retaining wall according to the present invention, FIG. 1B is a longitudinal front view of a key portion of the retaining wall, FIG. 1C is a cross-sectional view taken along the X1-X1 arrow of FIG. 1B, FIG. 1D is a cross-sectional view taken along the X2-X2 arrow of FIG. 1B, and FIG. 1E is an enlarged view of part (α) of FIG. (A) is a schematic cross-sectional plan view of the retaining wall in the retaining construction area, (B) is an enlarged view of part (β) of (A), (C) is an enlarged view of part (γ) of (A), and (D) is a schematic cross-sectional plan view of the main parts of a unit wall body with one intermediate wall. 1A to 1C are a cross-sectional plan view and a longitudinal front view showing the structure of the parent pile. 4A to 4C are a cross-sectional plan view and a longitudinal front view showing the structure of the side walls and the intermediate wall. This is a diagram showing steps 1 to 3 of the construction of the parent pile. This is a diagram of steps 4 to 6 showing the completion of construction of the parent pile. This is a diagram of steps 7 to 10 until the construction of the side wall is completed. This is a diagram of steps 11 to 14 until the construction of the intermediate wall is completed. 1A is an exploded perspective view of a drilling guide device, and FIG. 1B is a perspective view of a state in which a lower part of a drilling drill is connected to the drilling guide device. 1A is a front view of a drilling guide device attached to a drilling drill, FIG. 1B is a front view of the drilling guide device disassembled, FIG. 1C is a cross-sectional view of a main part of the drilling guide device, and FIG. 1D is a cross-sectional view of the connecting part between the drilling guide device and the drilling drill. 1A to 1C are diagrams showing the use state of the excavation guide device.

The following describes the embodiments of the earth retaining wall, the earth retaining wall construction method, and the excavation guide device of the present invention based on the drawings. First, the earth retaining wall will be described, followed by the earth retaining wall construction method and the excavation guide device. The earth retaining wall is constructed in the shape of a closed enclosure wall (see Figure 2(A)). Specifically, an earth retaining construction area A is set first. The earth retaining construction area A refers to the area for constructing the earth retaining wall on the land or site on which the earth retaining wall is to be constructed (see Figure 2(A)). The parent piles B1, side walls 4, and intermediate walls 5 that make up the earth retaining wall are constructed along the boundary line of the earth retaining construction area A (see Figure 2(A)).

The retaining construction area A is composed of straight line parts along the X and Y directions and multiple corners (see Fig. 2(A)). The X-direction line that determines the retaining construction area A is the area boundary line Jx, and the Y-direction line is the area boundary line Jy. The retaining construction area A also has protruding corners To, which are corners facing outward, and recessed corners Ti, which are corners recessed inward.

Here, for the sake of convenience in explaining the invention, the terms X direction and Y direction are used to indicate directions, and in principle, the horizontal direction of the retaining construction area A is taken as the X direction, the area boundary line Jx is taken as the horizontal line, and the vertical direction is taken as the Y direction, with the area boundary line Jy being taken as the vertical line (see Figure 2). However, for the X and Y directions, it is also possible to replace the X direction with the vertical direction and the Y direction with the horizontal direction, with the area boundary line Jx being taken as the vertical line and the area boundary line Jy being taken as the horizontal line.

In addition, the aforementioned parent piles B1, side walls 4, and intermediate walls 5 are present as structures for constructing the retaining wall in the retaining construction area A (see Figures 1(A), (B), (C), 2, 4(C), etc.). The parent piles B1 are arranged at a predetermined interval along the boundary line of the retaining construction area A, and side walls 4, 4 and two or one intermediate walls 5 are formed between each of the adjacent parent piles B1, B1 in the multiple parent piles B1 arranged along the boundary line of the retaining construction area A.

A part of the side wall 4 and a part of the intermediate wall 5 intersect in the width direction (horizontal direction), and these are connected in a continuous manner to form an earth retaining wall in the earth retaining construction area A. The partial wall body formed by the side wall 4 and intermediate wall 5 formed between the adjacent parent piles B1 and B is called the unit wall body B2 (see Figure 2).

The parent pile B1 is composed of a parent pile hole 1, an H-shaped steel 2 as the pile core, and a concrete support 3 (see Figure 3(A)). The H-shaped steel 2 is embedded in the parent pile hole 1 (see Figure 3(B)). The H-shaped steel 2 is fixed and supported in the parent pile hole 1 by the concrete support 3 (see Figure 3(C)). In constructing the parent pile B1, first, the parent pile hole 1 is excavated in the position in the retaining construction area A where the parent pile B1 is to be constructed, in order to drive the H-shaped steel 2 into the hole (see step 2 in Figure 5).

To make it easier to drive the H-shaped steel 2 into the ground, the drill shaft of the excavation machine is used to excavate the parent pile hole 1, which has an inner diameter larger than the H-shaped cross-sectional shape of the H-shaped steel 2. The H-shaped steel 2 is inserted upright into the parent pile hole 1 (see Figures 3(B) and (C) and Figure 6, step 5). The total length of the H-shaped steel 2 is slightly longer than the total depth of the parent pile hole 1, and when the H-shaped steel 2 is completely driven into the parent pile hole 1, the upper tip of the H-shaped steel 2 protrudes slightly from the opening of the parent pile hole 1.

The concrete support 3 is provided from the bottom to the approximate middle of the total depth of the parent pile hole 1 over the entire depth from the opening to the bottom of the parent pile hole 1 (see Figs. 1(B), (D), 3(B), (C)). The concrete support 3 covers the H-shaped steel 2 so that it is embedded in concrete from the bottom to the middle position in the longitudinal direction, and the outer periphery and bottom of the concrete support 3 are in close contact with the inner periphery and bottom of the parent pile hole 1, so that the H-shaped steel 2 is securely fixed and supported in the parent pile hole 1 (see Figs. 1(A), (B), (D)).

The concrete support 3 is formed by solidifying liquid cement milk injected into the parent pile hole 1. The parent pile hole 1 is then backfilled with the embankment that was removed during excavation and piled up around the opening of the concrete support 3 until it closes the opening of the parent pile hole 1 (see Figure 3(C) and Figure 6, step 6). Parent piles B1 with this configuration are constructed at a specified interval along the area boundary line Jx and area boundary line Jy of the retaining construction area A (see Figure 2(A)).

Next, the construction of the side wall 4 of the unit wall B2 constructed between adjacent parent piles B1, B1 will be explained. In principle, two side walls 4 are constructed (see Figures 1 (A), (B), and (C)). The side wall 4 is composed of a side wall hole 41 and a side wall concrete part 42 formed by solidifying cement milk injected into the side wall hole 41. The side wall 4 is approximately cylindrical (see Figures 1 (A), (C), Figures 2 (B), (C), and (D)).

Furthermore, part of the cylindrical outer shape of the side wall 4 enters the gap S between the two flanges 21, 21 of the H-shaped steel 2 of the parent pile B1, and the part of the side wall 4 that enters the gap S is configured to abut or be close to the web 22 of the H-shaped steel 2 (see Figures 1(A), (C), and 2). Also, the side wall hole 41 is structured so that a part of it inevitably intertwines with the parent pile hole 1 (see Figures 1(B), 4(A), (B), and Figure 7, steps 8 and 9, etc.).

The side wall 4 is set shallower than the depth of the parent pile B1. Specifically, the depth of the side wall 4 is slightly more than half the depth of the parent pile B (see Figures 1(B), (E), 4(A), (B)). The lower part of the side wall 4 and the upper part of the concrete support part 3 of the parent pile B1 have a part where they intersect in the depth direction (or vertical direction) (see Figures 1(A), (B), (C), (E)).

In other words, the above-mentioned configuration of the parent pile B1 and the side wall 4 is such that the depth dimension of the side wall 4 is greater than the depth dimension from the opening of the parent pile hole 1 to the upper end of the concrete support part 3 (see FIG. 1). In other words, if the depth dimension from the opening of the parent pile hole 1 to the upper end of the concrete support part 3 is H1, and the depth of the side wall concrete part 42 or the side wall hole part 41 of the side wall 4 is H2, then
H2>H1.

If the intersection point between the concrete support portion 3 and the side wall concrete portion 42 of the side wall 4 in the vertical direction (depth direction) is defined as an intersection portion 90, the intersection dimension h of the intersection portion 90 in the vertical direction is
h = H2 - H1.
Here, the intersection dimension h in the vertical direction (depth direction) between the concrete support portion 3 of the parent pile B1 and the side wall concrete portion 42 of the side wall 4 (see Figures 1(B) and (E)) is, specifically, if the depth of the parent pile B1 is about 10 m, the intersection dimension h of the intersection portion 90 is about 1 m.

In other words, the upper part of the concrete support part 3 of the parent pile B1 and the lower part of the side wall 4 have an intersection part 90 in the vertical direction, and the concrete support part 3 and the side wall concrete part 42 of the side wall 4 are continuously connected in the depth direction (or vertical direction). In addition, the intersection dimension h of the intersection part 90 is not limited to the above numerical value, but is changed appropriately depending on the depth dimension of the parent pile hole part 1 and the side wall hole part 41, and may be about 0.5 m to about 2 m.

The excavation of the side wall hole 41 in the side wall 4 and the injection of the cement milk are carried out before the cement milk for the construction of the concrete support portion 3 of the parent pile B1 has completely solidified and is still in a fluid state. In other words, the side wall hole 41 in the side wall 4 and the injection of the cement milk into the side wall hole 41 are carried out when the concrete portion of the concrete support portion 3 has not yet solidified and is in a liquid state and can be mixed with the cement milk that forms the side wall 4.

As a result, the concrete support portion 3 of the parent pile B1 and the side wall concrete portion 42 formed by the solidification of the cement milk in the side wall 4 are mixed together, and the concrete support portion 3 and the side wall concrete portion 42 of the side wall 4 are integrated together (see Figures 1, 4(B) and (C)).

The area where the pile hole 1 of the pile B1 has been backfilled with embankment will intersect with the side wall 4. During the process of injecting cement milk into the pile hole 1 of the pile B1 and the side wall hole 41 of the side wall 4, the cement milk will also flow into the pile hole 1, and the pile hole 1 will be backfilled with embankment and the cement milk injected into the side wall hole 41 will mix together.

Then, the cement milk injected into the side wall hole 41 inside the parent pile hole 1 and above the concrete support 3 mixes with the fill soil to form a mortar state, which hardens to form a cylindrical wall above the concrete support 3 with roughly the same diameter as the concrete support 3. This cylindrical wall is mortar-like and has different properties from the concrete support 3, but has sufficient strength, and the cylindrical wall and the side wall 4 are continuously interwoven in the vertical direction, forming a wall in which the parent pile B1 and the side wall 4 are continuous.

Next, the depth of the intermediate wall 5 is the same or approximately the same as the depth of the side wall 4 (see Figs. 1(A), (B) and 4(C)). The outer diameter of the intermediate wall 5 is larger than the outer diameter of the side wall 4. Furthermore, the cross section of the intermediate wall 5 perpendicular to the vertical direction and the cross section of the side wall 4 perpendicular to the vertical direction are configured to intersect. In other words, the side wall 4 and the intermediate wall 5 are configured to be continuously and partially intertwined in the vertical direction.

The intermediate wall 5 is composed of an intermediate wall hole 51 and an intermediate wall concrete section 52. First, the intermediate wall hole 51 is excavated, and cement milk is poured into the intermediate wall hole 51. The cement milk solidifies to form the intermediate wall concrete section 52, thereby forming the intermediate wall 5 (see Figure 4(C) and steps 12 to 14 in Figure 8).

The drilling of the intermediate wall hole 51 in the intermediate wall 5 and the injection of the cement milk are carried out before the cement milk for the construction of the side wall concrete portion 42 in the side wall hole 41 is completely solidified and is still in a fluid state. In other words, the intermediate wall hole 51 in the intermediate wall 5 and the injection of the cement milk into the intermediate wall hole 51 are carried out when the concrete portion of the side wall concrete portion 42 has not yet solidified and is in a liquid state and can be mixed with the cement milk that forms the intermediate wall 5.

As a result, the side wall concrete portion 42 of the side wall 4 and the intermediate wall concrete portion 52 of the intermediate wall 5 formed by the solidification of the cement milk in the intermediate wall concrete portion 52 are mixed together, and the side wall concrete portion 42 of the side wall 4 and the intermediate wall concrete portion 52 of the intermediate wall 5 are integrated.

In the unit wall body B2, two intermediate walls 5 are formed between the side walls 4, 4 located on both sides of the intermediate wall 5 (see Figures 1 and 2 (A) to (C)), or one intermediate wall 5 is formed (see Figure 2 (D)). When two intermediate walls 5 are formed in the unit wall body B2, the two intermediate walls 5, 5 are formed so as to intersect along the depth direction (up and down direction). Here, when excavating the intermediate wall hole portion 51 of the intermediate wall 5, an excavation guide device 6 may be used.

The structure and use of the excavation guide device 6 will be described later. In a set of unit walls B2, when there is one intermediate wall 5, the spacing between the H-shaped steels 2, 2 of the parent piles B1, B1 on both sides of the unit wall B2 is configured to be narrow. When there is one intermediate wall 5 in the unit wall B2, it is often used when the retaining construction area A is relatively small.

The side walls 4 and intermediate walls 5 that make up the parent pile B1 and unit wall body B2 are arranged as described above along the area boundary line Jx in the X direction of the earth retaining construction area A and the area boundary line Jy in the Y direction (see Figure 2). The inner edge of the flange 21 of the H-shaped steel 2 of the parent pile B1 arranged on the X direction side of the protruding corner To, that is, the outer edge of the flange 21 located inside the earth retaining construction area A, is located at the intersection of the area boundary line Jx and the area boundary line Jy (see Figure 2).

In addition, the edge of the inner flange 21 of the H-shaped steel 2 of the parent pile B1 arranged on the Y-direction side of the protruding corner To, in other words, the edge of the flange 21 located inside the earth retaining construction area A located outside the earth retaining construction area A, is located at a position a predetermined distance away from the intersection of the area boundary line Jx and area boundary line Jy. The inner flanges 21 of the H-shaped steel 2 of the parent pile B1 arranged along the area boundary line Jx and area boundary line Jy in the earth retaining construction area A are arranged so as to be aligned in a row along the area boundary line Jx and area boundary line Jy on which they are respectively arranged (see FIG. 2).

For the H-shaped steel 2 of the parent pile B1 located on the area boundary line Jx side at the protruding corner To of the retaining construction area A, the side wall 4 located closest to the parent pile B1 on the area boundary line Jx side fits directly between the two flanges 21, 21 of the H-shaped steel 2 along the area boundary line Jx (see Figure 2). In addition, the side wall 4 on the area boundary line Jy side located closest to the parent pile B1 on the area boundary line Jx side is arranged so as to incline toward the H-shaped steel 2 of the parent pile B1 on the area boundary line Jx side with respect to the linear row of other intermediate walls 5 and side walls 4, and is configured to fit between the two flanges 21, 21 of the H-shaped steel 2.

The H-shaped steel 2 of the parent pile B1 located at the inside corner Ti between the boundary lines Jx and Jy of the retaining construction area A has its web 22 inclined at 45 degrees to the X and Y directions (see Figures 2(A) and (C)). The flanges 21, 21 of the H-shaped steel 2 of the parent pile B1 located at the inside corner Ti are configured to accommodate the side walls 4, 4 located closest to the inside corner Ti between the boundary lines Jx and Jy.

As for the side walls 4 and intermediate walls 5 of the retaining construction area A described above, it is preferable that the diameter (outer diameter) of the roughly cylindrical intermediate wall 5 is equal to or greater than the diameter (outer diameter) of the roughly cylindrical side wall 4, and it is most preferable that the diameter (outer diameter) of the intermediate wall 5 is larger than the diameter (outer diameter) of the side wall 4. Furthermore, in the retaining construction area A, there may be cases where a gap is formed between the side wall 4 arranged in the Y direction adjacent to the parent pile B1 at the corner To and the H-shaped steel 2 of the parent pile B1. In such cases, an additional side wall 4 may be added as an auxiliary to fill the gap between the parent pile B1 and the side wall 4 [see Figures 2 (A) and (B)].

Next, the construction method and necessary equipment for the earth retaining wall will be explained. Before explaining the construction, the necessary equipment for the construction of the earth retaining wall will be explained. The main equipment used is a leaderless pile driver C, which is composed of a vehicle body 7 and an excavation device 8. The vehicle body 7 is a self-propelled vehicle equipped with tracks 72 on a main body 71 having a driver's cabin, and the main body 71 is equipped with an extendable boom 73 (see Figure 5).

The drilling device 8 includes a drilling drill 81, an auger 82 that rotates the drilling drill 81 in the axial direction, a tip drilling mechanism 83 attached to the tip of the drilling drill 81, and a loop head 84. The tip drilling mechanism 83 is designed to be replaceably attached to the drilling drill 81. If necessary, a drilling guide device 6 may be provided above the tip drilling mechanism 83 (see FIG. 11).

The loop head 84 is formed with an outer diameter larger than the outer diameter of the screw-shaped drill 81 and the tip excavation mechanism 83, and a digging blade (not shown) is also attached to the lower end (tip) of the loop head 84. The loop head 84 is formed in a screw shape, and the soil dug up by the digging blade of the tip excavation mechanism 83 and the digging blade of the loop head 84 are guided upward.

The loop head 84 and the tip drilling mechanism 83 are mounted on the same axis, and this axis is detachably attached to the drilling drill 81 via a mounting bolt. Although not shown, a loop material may be attached around the loop head 84, which may prevent the loop head 84 from coming into direct contact with the H-shaped steel 2 of the parent pile B1 during construction of the side wall hole 41.

Next, the construction of the retaining wall will be explained. To determine the area in which the retaining wall will be constructed, a retaining construction area A is set, which is composed of straight line sections along the X and Y directions and multiple corners (see Figure 2). As mentioned above, the straight line sections in the retaining construction area A are the area boundary line Jx along the X direction and the area boundary line Jy along the Y direction. Then, an outside corner To and an inside corner Ti are set, where the area boundary line Jx and the area boundary line Jy intersect.

The parent pile hole 1 is excavated at the boundary line Jx and boundary line Jy of the retaining construction area A by the drilling drill 81, loop head 84, and tip excavation mechanism unit 83 of the excavation device 8 (see steps 1 and 2 in Figure 5). Next, cement milk is injected from the bottom to the middle of the total depth in the vertical direction of the parent pile hole 1 (see step 3 in Figure 5). The cement milk is injected by spraying it from the loop head 84 and tip excavation mechanism unit 83 via a pump from the ground through the tubular drilling drill 81. The loop head 84 and tip excavation mechanism unit 83 are equipped with a nozzle so that the cement milk can be sprayed.

Next, the H-shaped steel 2 is inserted into the parent pile hole 1, and the piled soil that was created when the parent pile hole 1 was excavated is backfilled into the parent pile hole 1 to form the parent pile B1 (see steps 4 and 5 in Figure 6). The H-shaped steel 2 is embedded into the vertical parent pile hole 1 as accurately as possible, and the upper part of the H-shaped steel 2 is set so that it protrudes slightly from the opening of the parent pile hole 1. In this way, the parent piles B1 are constructed and placed at a specified interval along the area boundary line Jx and area boundary line Jy of the retaining construction area A (see step 6 in Figure 6).

Next, we move on to the process of constructing the side wall 4. Specifically, a side wall hole 41 is excavated so that a part of the side wall 4 fits into the gap S between the adjacent parent piles B1, B1 and between both flanges 21, 21 of each H-shaped steel 2, and a lower part of the side wall 4 intersects with the upper part of the cement milk injection part of the parent pile B1, that is, the part that becomes the concrete support part 3 when solidified [see steps 7 and 8 in Figure 7].

Then, cement milk is injected into the side wall hole 41 to construct the cylindrical side wall concrete portion 42 (see steps 9 and 10 in Figure 7). Such side walls 4 are constructed so that they fit into the gaps S between both flanges 21, 21 of all parent piles B1. At this time, a structure is created in which parts of the side walls 4, 4 in the width direction fit into both gaps between the flanges 21, 21 on both sides of the width direction of the parent pile B1. Here, the construction of the side walls 4, the excavation of the side wall hole 41 and the injection of cement milk are performed when the cement milk that constitutes the concrete support portion 3 of the parent pile B1 is in a soft state before it solidifies.

During the construction process of the side wall 4, part of the side wall hole 41 intersects with the parent pile hole 1 of the parent pile section B in the width direction. The parent pile hole 1 is backfilled with embankment on the top surface of the concrete support section 3, but since the embankment backfilled in the parent pile hole 1 is in an extremely soft and loose state, the cement milk injected into the side wall hole 41 flows into the parent pile hole 1 side, mixes appropriately with the backfilled embankment, and hardens into a mortar state. As a result, the side wall 4 and the parent pile B1 mix firmly together to form the wall body.

Next, we move on to the process of constructing the central wall 5. First, an intermediate wall hole 51 is excavated between both side walls 4, 4 located between adjacent parent piles B1, B1 to the same depth as the side wall hole 41 of the side wall 4 and so as to intersect with the side wall hole 41 in the diametric direction (see steps 11 and 12 in Figure 8). Next, cement milk is poured into the intermediate wall hole 51. When the cement milk solidifies in the intermediate wall hole 51, an intermediate wall concrete part 52 is formed, and the construction of the intermediate wall 5 is completed by intersecting a part of the side wall concrete part 42 of the side wall 4 in the width direction (see steps 13 and 14 in Figure 8). Here, a drilling guide device 6 described later may be used for the construction of the intermediate wall 5.

Next, the drilling guide device 6 will be described. The drilling guide device 6 serves to position the tip drilling mechanism 83 when drilling the intermediate wall hole 51 with the drilling device 8 of the drilling drill 81, loop head 84, and tip drilling mechanism unit 83 during construction of the intermediate wall 5 (see Figure 11). In addition, from the start of drilling, it serves as a guide to accurately maintain the direction of travel of the drilling drill 81, loop head 84, and tip drilling mechanism unit 83.

In other words, when the intermediate wall hole 51 is excavated by the excavation device 8, the excavation drill unit 81 serves to excavate the intermediate wall hole 51 in an accurate position by not approaching the intermediate wall hole 51 in a biased manner toward the side wall hole 41 of the adjacent side wall 4. Furthermore, the blade material 63 of the excavation guide device 6 also serves to stir the soil and the injected cement milk within its movable range during the excavation work.

The drilling guide device 6 is composed of a guide body 61, two blade holding members 62, and two blade holding members 62 (see Figures 9 and 10). The guide body 61 has a shaft support portion 61a, a connecting protrusion portion 61b, and a connected portion 61c. The two blade holding members 62 are attached to the shaft support portion 61a.

The connecting protrusion 61b is connected to the lower end of the drilling drill 81 and has a circular or polygonal cross section. The lower end of the drilling drill 81 is formed with a connecting hole 81a into which the connecting protrusion 61b is inserted. The connecting protrusion 61b is inserted into the connecting hole 81a of the drilling drill 81 and fixed with a fastener 64 such as a bolt or nut. The connecting portion 61c of the guide body 61 is connected to the loop head 84 and the tip drilling mechanism part 83 of the drilling device 8 (see Figures 10(A) and (B)).

The blade retaining member 62 is composed of a semicircular arch-shaped bearing portion 62a, a connecting plate portion 62b extending outward from both ends of the bearing portion 62a in the width direction, and a blade mounting plate portion 62c extending radially from a predetermined position of the bearing portion 62a. The bearing portions 62a, 62a of both blade retaining members 62, 62 hold the shaft support portion 61a of the guide body 61 between them (see FIG. 9(A)).

The inner diameter of the circular inner circumference formed by the symmetrical joining of the two bearing parts 62a, 62a is set to be approximately equal to the outer diameter of the shaft support part 61a. The connecting plate parts 62b, 62b are fixed to each other with fasteners 64 such as bolts and nuts, and the two blade retainers 62, 62 are rotatably attached to the shaft support part 61a of the guide body 61. The connecting plate part 62b and the blade attachment plate part 62c have bolt holes for fasteners 64 such as bolts and nuts.

The blade material 63 is attached to the blade holding material 62 so that it can be replaced. The blade material 63 has a cross-sectional shape perpendicular to the longitudinal direction that is generally T-shaped. The blade material 63 has a bolt hole on one longitudinal side for fasteners 64 such as bolts and nuts for attachment to the blade attachment plate portion 62c.

The blade material 63 is fixed to the blade mounting plate portion 62c of the blade retaining material 62 via fasteners 64 such as bolts and nuts. Here, in the theory of connecting the blade mounting plate portions 62c, 62c, by arranging the bolt holes vertically, the fasteners 64 such as bolts and nuts are also arranged vertically, which reduces the resistance of the soil during excavation work.

When both blade retaining materials 62, 62 are attached to the shaft support portion 61a of the guide body 61, both blade mounting plate portions 62c, 62c are set to be located on the extension of the diameter of the circular cross section of both bearing portions 62a. In other words, both blade mounting plate portions 62c, 62c are provided so as to be approximately point-symmetrical with respect to the center of the cross section diameter of the shaft support portion 61a, and the two blade materials 63, 63 attached to both blade mounting plate portions 62c, 62c are also positioned approximately point-symmetrical.

Blade materials 63 are prepared in various different lengths in the longitudinal direction. Two blade materials 63 are attached to the excavation guide device 6. In the case where there are two intermediate walls 5, and there are two intermediate walls 5 between adjacent parent piles B1, B1, each intermediate wall 5 is provided at a position offset from the center of both H-shaped steels 2, 2 between the adjacent parent piles B1, B1.

Therefore, the two blade materials 63, 63 are used with different lengths in the longitudinal direction. In other words, one intermediate wall 5 is constructed in a position biased toward one of the H-shaped steels 2 from the middle between the two H-shaped steels 2, 2, and the other intermediate wall 5 is constructed in a position biased toward the other H-shaped steel 2, so the lengths of the two blade materials 63, 63 are different so that both tips can abut against both H-shaped steels 2, 2. Also, when there is one intermediate wall 5 between adjacent parent piles B1, the intermediate wall 5 is located at the center of both H-shaped steels 2, 2 between the adjacent parent piles B1, B1, and two blade materials 63 with the same length in the longitudinal direction are used.

The blade material 63 attached via the blade retaining material 62 attached to the guide body 61 can rotate on a horizontal plane together with the guide body 61 which rotates with the rotation of the drilling drill 81, and when the blade material 63 abuts against the flange 21 of the H-shaped steel 2, it stops rotating together with the blade retaining materials 62, 62 (see Figure 11).

The tips of the two blade materials 63 of the drilling guide device 6 enter between the two flanges 21, 21 of the H-shaped steel 2 of the parent pile B1, and the tips of the blade materials 63 approach or abut the flanges 21, 21 or web 22 of the H-shaped steel 2. As the drilling drill 81 rotates, the drilling guide device 6 itself also tries to rotate, but when the blade materials 63 abut against the flanges 21, 21, the drilling guide device 6 rotates freely relative to the shaft support portion 61a of the guide body 61, and the axis of the drilling drill 81 is maintained in a constant position by the H-shaped steel 2 of the adjacent parent piles B1, and the intermediate wall hole 51 of the intermediate wall 5 can be accurately drilled without being affected by the side wall hole 41 of the nearby side wall 4.

The use of the drilling guide device 6 will now be explained. The drilling guide device 6 serves to drill the intermediate wall hole 51 at an accurate position while maintaining the verticality during construction of the intermediate wall 5. The tip portions of the two blade members 63, 63 of the drilling guide device 6 are inserted into the gap S formed by the two flanges 21, 21 and the web 22 of each of the adjacent H-shaped steels 2, 2 of the adjacent parent piles B1, B1.

At this time, the tip portions of both blade materials 63, 63 of the drilling guide device 6 are set so that they can abut against both flanges 21, 21 or the web 22 of the H-shaped steel 2. Then, drilling is started by the drilling drill 81, loop head 84, and tip drilling mechanism 83, and both blade materials 63, 63 use both H-shaped steels 2, 2 roughly like guide rails to perform accurate drilling work, and can perform drilling work without being affected by the side wall hole 41 adjacent to the intermediate wall hole portion 51.

In addition, although not shown, the upper part of the concrete support part 3 of the parent pile B1 and the lower part of the side wall 4 may be adjacent to each other without intersecting in the vertical direction. Even in this case, by injecting cement milk into the side wall hole 41, the cement milk flows into the backfilled soil above the concrete support part 3 of the parent pile hole 1, turning it into a mortar state, which then solidifies, essentially integrating the parent pile B1 and the side wall 4.

A...Earth retaining construction area, B1...Main pile, B2...Unit wall, 1...Main pile hole, 2...H-shaped steel,
21... flange, 3... concrete support portion, 4... side wall, 41... side wall hole portion, 5... intermediate wall,
51: intermediate wall hole portion; 6: drilling guide device; 61: guide body; 61a: shaft support portion;
62...Blade retainer, 62a...Bearing portion, 62b...Connecting plate portion,
62c...blade mounting plate portion, 63...blade holding material, 90...intersection portion.

Claims (3)

A retaining wall in the form of a closed enclosure wall, comprising: a retaining construction area formed by straight portions and a plurality of corners along the X-direction and the Y-direction; parent piles arranged along the X-direction and the Y-direction and having H-shaped steel; a cylindrical side wall formed of cement milk; and an intermediate wall partially intersecting with the side wall formed of the cement milk;
The flanges on one side of the H-shaped steel of the parent pile in the straight portion arranged along the X-direction and the Y-direction of the retaining construction area face the inner side of the retaining construction area and are arranged so that the inner flanges are aligned in a straight line along the X-direction and the Y-direction,
A retaining wall characterized in that the H-shaped steel is formed as a concrete support portion using cement milk from the lower end to the middle of the depth of the parent pile, the depth of the side walls and the intermediate wall is set shallower than the depth of the parent pile, the lower part of the side walls intersects with the upper part of the concrete support portion of the parent pile, and a part of the side walls is contained within the gap between the two flanges of the H-shaped steel. The retaining wall according to claim 1, characterized in that the intermediate walls are made up of two pieces. The retaining wall according to claim 1, characterized in that the intermediate wall is a single piece.

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