JP3309303B2 - Construction method of underground diaphragm wall in frozen soil - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an underground continuous wall in a frozen ground in which a ground continuous wall constituting a mountain retaining wall, a water blocking wall, a foundation of a structure or an underground structure is applied to a ground having a frozen soil portion. Concerning the construction method.

[0002]

2. Description of the Related Art Reinforcing shells formed by connecting steel box-type sheet piles are built on underground continuous walls which constitute mountain retaining walls, water blocking walls, foundations of structures or underground structures. The underground continuous wall having such a structure is constructed by, for example, the following procedure. First, the preparatory excavation groove for constructing the preparatory element that constitutes the preparatory construction part of the underground continuous wall is filled with a stable liquid such as bentonite muddy water, while being separated from each other by approximately one element length. It is formed by an excavator while stabilizing steel. Then, a steel box-type sheet pile is continuously connected to the preceding excavation trench while consolidating as necessary, forming a shell, and concrete is poured into this shell while replacing the stabilizing liquid with a tremy pipe. Build the preceding element. Then, the succeeding element is constructed between the preceding elements constructed with a space therebetween in the same procedure as described above, and the underground continuous wall is constructed.

[0003]

By the way, in order to prevent collapse of a trench wall in an extremely soft ground or the like, it has been considered to construct a continuous underground wall by freezing the ground, but has the following problems. Therefore, it has not been realized. In other words, of the concrete poured into the shell of the steel box-type sheet pile, the one located inside the frozen soil part is hardened to some extent because the concrete itself generates heat when hardened, but is close to the frozen soil part In some parts, the heat is deprived in the frozen soil part, and before the solidification is complete, the moisture is frozen and the quality is deteriorated. This problem naturally occurs in the case where the underground continuous wall is constructed on the ground having a frozen soil portion in a cold region or the like.

[0004] Accordingly, an object of the present invention is to provide a method for constructing a continuous underground wall in frozen soil which can maintain good quality of concrete even when applied to the ground having a frozen soil portion.

[0005]

In order to achieve the above object, the present invention is provided in a trench excavated and formed in a ground having a frozen soil portion, and a shell formed by a steel box type sheet pile. A method for constructing a frozen ground underground continuous wall by casting concrete therein, wherein at least a range from the ground surface side to the underground side of the frozen ground part is wider than the shell body, and a trench is excavated and formed. In the excavated groove, the steel box-type sheet pile is erected to form a shell, and a portion having a wider width than the shell of the groove and the shell having a heat insulating property are provided between the shell and the shell. It is characterized in that it is backfilled with a returning material, concrete is poured into the shell and hardened.

[0006]

According to the present invention, a groove is excavated by forming at least the area from the ground surface side to the underground side of the frozen soil part wider than the shell body, and a steel box-type sheet pile is formed in the excavated groove. To form a shell body, and backfill the space between the part of the groove wider than the shell body and the shell body with a heat-insulating backfill material, cast concrete in the shell body, and harden it Therefore, the concrete cast inside the shell,
At the time of hardening, the heat transfer between the frozen ground and the frozen ground is interrupted by the backfill material having heat insulation properties, so that the heat such as the heat generated during the hardening itself is taken away by the frozen ground. Disappears.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for constructing an underground frozen ground wall according to a first embodiment of the present invention will be described below with reference to FIGS. In the first embodiment, as shown in FIG. 1, a range of a predetermined depth from the ground surface side is a frozen frozen soil portion 1, and a non-frozen soil portion that is not frozen is further underground. An example will be described in which a groove 4 is excavated and formed in the ground 3 which is 2 and an underground continuous wall is constructed in the groove 4.

First, a steel box type sheet pile employed in the first embodiment will be described. As shown in FIG. 3, the steel box-shaped sheet pile 10 </ b> A has a rectangular shape and an opening formed in a substantially rectangular web 11 and both side edges of the web 11 so as to be parallel to each other. It has a substantially H-shaped cross section including a pair of flanges 12 having no flange. An arc-shaped portion 13 for connecting adjacent ones is provided on both end edges of the flange 12.
Are provided continuously along the longitudinal direction. The arc-shaped portion 13 has a substantially arc-shaped cross section in which the outer side is opened with respect to the flange 12.

One of the adjacent steel box-type sheet piles is a steel box-type sheet pile 10A having the above-mentioned shape, and the other one is provided on all the arc-shaped portions 13 as shown in FIG. A main plate portion 15 having a substantially rectangular shape and a length of the main plate portion 1;
5. A coupling joint member 17 having substantially plate-shaped engaging portions 16 provided substantially at right and left sides of the main plate portion 15 on both side edge portions of the connecting joint member 17, respectively.
Is used in a state in which one of the engaging portions 16 is engaged with the steel box type sheet pile 10B. Then, as shown in FIG. 5, for example, after the steel box-shaped sheet pile 10B to which the coupling joint member 17 is joined is erected, the steel box-shaped sheet pile 10A to which the coupling joint member 17 is not joined is cut into a circle. The work is carried out underground by fitting these inside the arc-shaped portion 13 while fitting them so that the engaging portion 16 of the connecting joint member 17 of the steel box-shaped sheet pile 10B in the built-in state is positioned. The shell 18 is formed by repeating as appropriate in accordance with the size of the element to be divided and constructed of the continuous wall.

Next, the main steps of the method of constructing a continuous underground wall in frozen soil according to the first embodiment using the steel box type sheet piles 10A and 10B will be described in order. The following steps are:
This step is common to both the preceding element and the following element described in the related art. First, as shown in FIG. 6, at a predetermined construction position of the ground 3, the range from the ground surface side to the underground side of the frozen soil part 1 is set to be a wide groove 4 a wider than the shell 18, and from the underground side of the frozen soil part 1. A groove 4 having an irregular cross-sectional shape in which the range of the unfrozen soil portion 2 up to a predetermined depth is a narrow groove portion 4b having substantially the same width as the shell 18 is filled with a stable liquid 5 such as bentonite muddy water to stabilize the inner wall surface. And excavation with an excavator (not shown). Here, a stable liquid 5 such as bentonite muddy water is used.
May be mixed with antifreeze to prevent freezing,
Circulated or heated.

As shown in FIG. 7, the steel box-type sheet piles 10A and 10B, which are substantially formed at a height corresponding to the distance from the bottom of the narrow groove 4b of the groove 4 to the ground surface, are adjacent to each other. The fittings are connected and erected to form the shell 18. Next, as shown in FIG. 8 and FIG.
A backfill material 20 having heat insulating properties is poured into the space defined by the shell and the shell 18 while substituting the stabilizing liquid 5 with a tremy tube (not shown), and this portion is backfilled. Here, as the backing material 20 having the above-mentioned heat insulating properties, for example, mixed soil mixed with styrofoam beads, poorly mixed mortar containing less cement than usual, muddy mortar, less cement than usual Poorly-mixed concrete or the like will be used. In the case where the styrene foam beads mixed soil is used as the backfill material 20, it is also possible to use a package in which the styrofoam beads and the soil are packed in a bag, that is, to package the soil, thereby preventing the styrene foam beads from being separated from the soil. be able to. In addition, when poorly mixed concrete is used as the backfill material 20, the use of artificial lightweight aggregate can increase the heat insulation. This is because the artificial lightweight aggregate becomes vitreous once the surface is melted and hardened, and becomes void due to impermeability of water, thereby increasing heat insulation.

Next, as shown in FIGS. 1 and 2, a concrete 2 is placed in a shell 18 made of the steel box-shaped sheet piles 10A and 10B while replacing the stabilizer 5 with a tremy pipe (not shown).
1 is cast. Then, in this state, the cast concrete 21 is cured. In such a process, the ground 3 having the frozen soil part 1 is constructed by constructing the preceding element and the succeeding element connecting the preceding elements.
An underground continuous wall 22 is constructed therein. Then, for example, when excavating the ground on one side of the underground continuous wall 22, an unnecessary layer of the backfill material 20 is removed as necessary.

In constructing the preceding element,
The groove 4 is excavated so that the wide groove portion 4a becomes wide with respect to the entire circumference of the shell 18 in the horizontal direction, whereby the layer of the backfill material 20 between the wide groove portion 4a and the shell 18 is formed. It will form an annular shape in plan view. When the succeeding element is constructed between the preceding elements, the side elements of the preceding element are exposed, and the wide groove 4a is widened in the direction of the wall thickness of the shell 18 so that the width of the wide element 4a is increased. When the trench 4 is excavated including a part of the layer of the backfill material 20 on the side of the following element construction side, the layer of the backfill material 20 formed on both sides in the wall thickness direction of the shell 18 thereafter becomes the layer of the preceding element. It will be continuous with the layer of the backfill material 20 left on both sides in the wall thickness direction. As a result, a good heat insulating property can be obtained in all directions by the layer of the backfill material 20 not only when constructing the preceding element but also when constructing the succeeding element.

As described above, according to the first embodiment, the range from the ground surface side to the underground side of the frozen ground 1 is the shell 18.
The groove 4 is excavated and formed into a wider groove 4a, and a steel box-type sheet pile 10 is formed in the excavated groove 4.
A and 10B are erected to form a shell 18, and a back-insulating material 2 having a heat insulating property is provided between the wide groove 4a of the groove 4 and the shell 18.
0, the concrete 21 is cast into the shell 18 and the concrete 21 is hardened. Therefore, the concrete 21 cast into the shell 18 has a heat-insulating backfill when hardened. The transmission of heat to and from the frozen soil part 1 is cut off by the material 20, so that heat such as heat generated during the hardening of the frozen soil part 1 itself is not lost to the frozen soil part 1. Therefore, even when applied to the ground 3 having the frozen soil part 1, the shell 1 made of the steel box-type sheet piles 10A and 10B can be used.
The concrete 21 poured into the inside 8 does not freeze the moisture before solidification, not to mention the part close to the frozen soil part 1, so that the quality of the concrete 21 is maintained well. Become. This also makes it possible to realize the construction of an underground continuous wall by freezing the ground in order to prevent the collapse of the groove wall in an extremely soft ground or the like. Moreover, when the concrete 21 is poured into the shell 18, the shell 18 is stabilized by the backfilling material 20.
Therefore, for example, there are various merits such as being suitable for construction of a tall underground continuous wall. The width of the wide groove 4a is set such that the layer of the backfill material 20 exhibits a sufficient heat insulating effect between the concrete 21 and the frozen soil part 1.

In general, the ground 3 has at least the frozen soil portion of the steel box-type sheet piles 10A and 10B because the frozen soil portion 1 is on the ground surface side and the unfrozen soil portion 2 is below the ground portion, as described above. The upper part of the part 1 is connected by using the above-described connecting joint member 17 that is continuous in the longitudinal direction in order to prevent the backfill material 20 from flowing into the inside. Further, in a predetermined range located in the unfrozen soil portion 2, for example, as shown in FIG. 10, a structure in which a plurality of short connecting joint members 17 are joined at a predetermined pitch so as to form a slit between adjacent members. By adopting and turning the concrete outward from the slit, it is also possible to carry out consolidation prior to backfilling. In this case, if the compacted concrete is poured with the canvas sheet or the like stuck, the canvas sheet adheres to the ground side by the pressure of the compacted concrete, whereby the concrete leaks to the ground side with the canvas sheet. And prevent concrete from sticking to the ground. For example, in order to prevent the backfill material 20 from flowing into the shell 18 in a later step, the consolidation concrete is cast to a position where the opening of the bottom portion of the shell 18 including the slit is closed. do it. Of course, it is also possible to pour the solidified concrete in the entire area of the unfrozen soil portion 2.

The joint structure of the steel box type sheet piles 10A and 10B is not limited to the above, and various known structures can be applied. For example, as shown in FIG. 11, a structure or the like in which the arc-shaped portions 13 are engaged with each other can be adopted by making the arc-shaped portions 13 engageable with each other. In addition, for example, if necessary, the web 1
It is also possible to use steel box-type sheet piles 10A and 10B provided with an opening 24 penetrating in the thickness direction in FIG. further,
It is easier to set the tremy tube by setting the tremy tube to the outside surface of the steel box-shaped sheet piles 10A and 10B in advance by attaching a not-shown tremy tube for injecting the backfill material 20 before embedding. This is advantageous.

Next, a method for constructing an underground frozen ground wall according to a second embodiment of the present invention will be described below with reference to FIGS. 12 to 15, focusing on the differences from the first embodiment. In the second embodiment, first, as shown in FIG. 12, at a predetermined construction position of the ground 3, in addition to the range from the ground surface side to the underground side of the frozen soil part 1, and further from the underground side of the frozen soil part 1 The groove 4 having the same cross-section in which the range of the unfrozen soil portion 2 to a predetermined depth is wider than the shell 18 is formed by excavation while filling the stabilizing liquid 5 to stabilize the inner wall surface. Then, as shown in FIG. 13, the steel box-type sheet piles 10A, 10B
To form the shell 18. At this time, the reinforced concrete 23 is poured into the bottom of the groove 4 while replacing the stabilizing liquid 5 with a tremy pipe (not shown). In this case, the plurality of short connecting joint members 17 described above are provided on the steel box-shaped sheet piles 10A and 10B in a predetermined range on the bottom side located in the unfrozen soil portion 2.
A structure in which slits are formed between each other can be adopted. In response, the consolidation concrete 23 closes the opening of the bottom portion of the shell 18 including the slit, for example, to prevent the backfill material 20 from flowing into the shell 18 in a later step. It is driven to the position. Of course, it is also possible to cast the concrete 23 in the whole area of the unfrozen soil portion 2.

Next, at the time when the compacted concrete 23 has been cured, as shown in FIG. 14, a back-insulating material 20 having heat insulating properties is placed in a space defined by the groove 4 and the shell 18. It is poured while replacing the stabilizing solution 5 with a tremy tube (not shown), and this portion is backfilled. Then, as shown in FIG. 15, the concrete 2 is replaced in the shell 18 by the steel box-shaped sheet piles 10A and 10B with the stabilizing liquid 5 by a not-shown tremy tube.
1 is cast. Then, the concrete 21 is hardened in this state. In such a process, the underground continuous wall 22 is constructed in the ground 3 having the frozen soil part 1 by constructing the preceding element and the succeeding element that connects the preceding elements.

According to the second embodiment described above, the same effect as that of the first embodiment can be obtained, and in addition, since it is not necessary to excavate the groove 4 to have an irregular cross-sectional shape, the setup change of the excavator can be performed. Construction is facilitated because it becomes unnecessary, and moreover, since the gap between the bottom of the groove 4 and the steel box-shaped sheet piles 10A and 10B is large, there is an advantage that solidification can be reliably performed.

[0020]

As described above in detail, according to the method for constructing a submerged ground wall in frozen ground according to the present invention, a trench is excavated by making at least the area from the ground surface side to the ground side of the frozen ground part wider than the shell body. In addition to forming the shell, a steel box-type sheet pile is erected in the excavated groove to form a shell, and a heat insulating property is provided between a portion formed wider than the shell of the groove and the shell. Since the concrete back into the shell is hardened by backfilling with the backfill material having it, the concrete poured into the shell is hardened by the backfill material, The transmission is cut off, so that heat such as heat generated at the time of hardening itself is not taken by the frozen soil portion. Therefore, even when applied to the ground having a frozen soil part, the concrete poured into the shell of the steel box-type sheet pile will freeze the moisture before solidifying any part, not to mention the part close to the frozen soil part. As a result, the quality of the concrete is maintained well.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view taken along the line XX in FIG. 2 showing a state after placing concrete into a shell body in a method of constructing a frozen ground in-ground continuous wall according to a first embodiment of the present invention.

FIG. 2 is a plan sectional view taken along the line YY in FIG. 1 showing a state after the concrete is poured into the shell body in the method of constructing a ground wall in frozen ground according to the first embodiment of the present invention.

FIG. 3 is a perspective view showing one of the steel box-type sheet piles used in the method for constructing a frozen ground in-ground continuous wall according to the first embodiment of the present invention.

FIG. 4 is a perspective view showing the other side of the steel box-type sheet pile used in the method for constructing a frozen ground inland ground wall according to the first embodiment of the present invention.

FIG. 5 is a plan view showing a connection state of steel box-type sheet piles used in the method of constructing a ground wall in frozen ground according to the first embodiment of the present invention.

FIG. 6 is a cross-sectional view taken along a line corresponding to line XX in FIG. 2 showing a state at the time of trench excavation in the method of constructing a frozen ground in-ground continuous wall according to the first embodiment of the present invention.

FIG. 7 is a cross-sectional view taken along a line corresponding to line XX in FIG. 2, showing a state when the shell is formed by the steel box-shaped sheet pile in the method for constructing a frozen ground inland ground wall according to the first embodiment of the present invention. It is.

FIG. 8 is a cross-sectional view taken along a line corresponding to line XX in FIG. 2 showing a state at the time of backfilling in the method of constructing a frozen ground in-ground continuous wall according to the first embodiment of the present invention.

FIG. 9 is a plan sectional view taken along a line corresponding to the line YY in FIG. 1 showing a state at the time of backfilling in the method of constructing a frozen ground in-ground continuous wall according to the first embodiment of the present invention.

FIG. 10 is a perspective view showing a modification of the steel box-type sheet pile used in the method for constructing a continuous ground wall in frozen ground according to the first embodiment of the present invention at the time of coping with rooting.

FIG. 11 is a perspective view showing another example of the steel box-type sheet pile used in the method for constructing a frozen ground inland continuous wall according to the first embodiment of the present invention.

FIG. 12 is a view illustrating a state of excavating a trench in the method for constructing a frozen ground inland ground wall according to a second embodiment of the present invention, taken along the line XX in FIG. 2;
It is sectional drawing which follows the line equivalent to a line.

FIG. 13 is a cross-sectional view taken along a line corresponding to line XX in FIG. 2, showing a state where a shell is formed by a steel box-shaped sheet pile in the method of constructing a frozen ground inland ground wall according to the second embodiment of the present invention. It is.

FIG. 14 is a view illustrating a state of backfilling in the method of constructing the underground frozen ground wall in accordance with the second embodiment of the present invention at the time of backfilling, and FIG.
It is sectional drawing which follows the line equivalent to a line.

FIG. 15 is a cross-sectional view taken along a line corresponding to line XX in FIG. 2, showing a state after placing concrete into a shell body in the method of constructing a frozen ground in-ground continuous wall according to the second embodiment of the present invention. .

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Frozen ground 3 Ground 4 Groove 10A, 10B Steel box-shaped sheet pile 18 Shell 20 Backfill material 21 Concrete

Continuation of the front page (72) Inventor Takuro Odawara Shimizu Construction Co., Ltd. 1-3-2 Shibaura, Minato-ku, Tokyo (56) References JP-A-60-92514 (JP, A) JP-A-3-295926 (JP, A) JP-A-1-275806 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) E02D 5/20 102 E02D 5/18 102 E02D 3/115

Claims (1)

(57) [Claims] 1. Construction of an underground continuous wall in frozen ground which is provided in a trench excavated and formed in the ground having a frozen soil portion, formed of a shell body with a steel box-shaped sheet pile, and casts concrete therein. A method wherein at least a range from the ground surface side to the underground side of the frozen soil part is wider than the shell body to excavate and form a groove, and the steel box-type sheet pile is built in the excavated groove. And a shell body is formed, and a space formed between the portion of the groove wider than the shell body and the shell body is backfilled with a heat-insulating backfill material. Concrete is poured into the shell body and hardened. A method for constructing a ground wall in a frozen ground, wherein