JP2003268790A - Method for reducing sinking of soft ground - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for inexpensively reducing sinking of soft ground without taking much time when forming a bank on the soft ground to construct a road, a parking facility or the like. <P>SOLUTION: High grade earth and sand with little danger of sinking is laid on the soft ground 11 to form the bank 12. A precast pile 21 is driven into the bank 12 and the soft ground 11 and a solidification layer 13 is formed on the bank 12 and the precast pile 21 so that a pile head 22 of the precast pile 21 is buried 10 cm or more. A pavement 14 is constructed on the solidification layer 13 and the precast pile 21, the bank 12, the solidification layer 13 and the pavement 14 are united. Loads of the bank 12, the solidification layer 13, the pavement 14, and vehicles or the like acting on the soft ground 11 is transmitted to the ground in a deep part of the soft ground 11 from a circumferential face and tip of the precast pile 21, and they are directly transmitted to a soft ground 11 surface via the bank 12. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for reducing settlement of soft ground.

[0002]

2. Description of the Related Art When embankment is carried out on soft ground such as peat ground or cohesive ground to construct roads, parking lots, etc., soft piles such as wooden piles, concrete piles, and steel piles After driving a large number of piles to the required depth at predetermined intervals, connect the pile heads to each other with a connecting material such as wire or rope in a net shape,
A pile net method for improving soft ground is widely adopted by laying sand or the like on it to form a mat body, and further laying a sheet for civil engineering or the like on the top to perform embankment. According to this method, the pile, the connecting member, and the sheet material are integrated, and the embankment load acts on the deep layer without directly acting on the soft ground surface, so that the settlement of the ground due to the embankment load can be stably reduced. .

However, in this construction method, all the pile heads of a large number of piles must be connected in a mesh shape in the vertical, horizontal, and diagonal directions with a connecting material, which is very time-consuming and therefore the construction period. However, there is a problem that the construction cost may be delayed.

By the way, in Japanese Patent Laid-Open No. 10-317307, a plurality of columnar bodies are constructed on a soft ground with a length not reaching the support layer and with an improvement rate of 10 to 50%. Lay a shallow improved soil layer by mixing and solidifying either or both of additives and additives to the soil and solidifying material and solidify, and construct a road pavement on the shallow improved soil layer. A construction method has been proposed, and according to this method,
The problems described above can be avoided.

[0005]

However, in the construction method proposed in Japanese Patent Laid-Open No. 10-317307, the improvement rate, which is the ratio of the cross-sectional area of the columnar body to the dominant area of one columnar body, is 10 to 10. It is 50%, and there is a demand to reduce this number to reduce the number of piles to be laid, and / or to reduce the pile diameter to further reduce the material costs and construction costs involved in pile construction. However, there is a problem that the shape of the surrounding ground may be deformed when the columnar body is constructed. Further, in the proposed construction method, since the columnar body is first constructed on the soft ground, various large heavy equipment for constructing the columnar body is directly installed on the soft ground to construct the columnar body. However, it is difficult to stably install a large heavy machine on soft ground for a long period of time, and there is a problem in that the safety of construction in constructing a columnar body may be impaired.

An object of the present invention is to propose a method for reducing the settlement of soft ground which can meet the above-mentioned demands in the prior art and solve the problems.

[0007]

In order to solve the above-mentioned problems, according to the invention of claim 1, there is provided a method for reducing the settlement of soft ground by using ready-made piles. Forming embankment by laying less high-quality earth and sand, placing the ready-made pile on the embankment and the soft ground, forming a solidified layer on the embankment and the ready-made pile, on the solidified layer The pavement is constructed to integrate the ready-made pile, the embankment, the solidified layer, and the pavement, and the load of the embankment, the solidified layer, the pavement, and other vehicles on the soft ground is applied to the ready-made pile. A method for reducing subsidence of soft ground is proposed, in which it is transmitted from the peripheral surface and the tip to the deep ground of the soft ground and is directly transmitted to the soft ground surface via the embankment.

According to the invention of claim 2, in the invention of claim 1, there is proposed a method for reducing the settlement of soft ground by causing the pile head of the ready-made pile to penetrate into the solidified layer.

According to the invention of claim 3, in the invention of claim 1, the pile head portion of the ready-made pile is provided in the solidified layer by 10c.
A method for reducing subsidence of soft ground is proposed in which the penetration is performed for m or more.

According to the invention of claim 4, in the invention of claim 1, 2 or 3, the improvement rate, which is the ratio of the cross-sectional area of the ready-made pile to the control area of one of the ready-made pile, exceeds 10%. A method to reduce the settlement of soft ground is proposed.

According to the invention of claim 5, claims 1, 2 and
In the third or fourth aspect of the invention, a method for reducing settlement of soft ground is proposed, in which the solidified layer is constructed by mixing a solidifying material in an upper layer portion of the embankment.

According to the invention of claim 6, claims 1, 2 and
In the third or fourth aspect of the invention, a method of reducing settlement of soft ground is proposed, in which soil and sand and a solidifying material are mixed in advance and laid on the embankment to construct the solidified layer.

According to the invention of claim 7, claims 1, 2,
In the invention of 3, 4, 5 or 6, there is proposed a method for reducing settlement of soft ground, in which the embankment is formed on an excavated surface obtained by excavating the soft ground to a predetermined depth.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION An example of an embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows the method of the present invention to reduce the subsidence of soft ground in order to prevent the soft ground from sinking during and after the construction when embankment is built on the soft ground to construct a road or a parking lot. FIG. 6 is a process explanatory view for explaining an example of an embodiment of performing.

First, the embankment 12 is formed on the soft ground 11 by laying a desired thickness of sand having a low risk of sinking (FIG. 1 (A)). After this, the embankment 12 places various large-scale heavy equipment for driving ready-made piles, and even if the heavy-duty construction work is performed, the large-scale heavy equipment does not tilt or fall over, and the safe construction of the ready-made piles can be performed. It has the property that it can be performed.

Next, a known number of ready-made piles 21 such as wooden piles, concrete piles, steel pipe piles, etc. are driven to a required depth at a predetermined number of intervals, and the pile head surface of the pile head 22 of the ready-made piles 21. 22a
Is set up so that it is embedded at a predetermined depth in the embankment 12 (FIG. 1 (B)). Here, the two ready-made piles 21 are shown to be placed, but the ready-made piles 21 may be any number,
The required number may be set. Further, the diameter and length of the ready-made piles 21 and the installation interval are determined by the allowable subsidence amount required for the constructed road, parking lot, and the like.

Then, in the upper layer portion of the embankment 12 and the thickness portion below the pile head surface 22a of the ready-made pile 21 to the depth position, powder or slurry of cement, cement solidifying material,
A solidifying material such as quicklime is mixed and hardened to form a solidified layer 13 (FIG. 2C). Depending on the water content of the embankment 12,
In some cases, the solidified layer 13 is formed by compaction after mixing, and in other cases, the solidified layer 13 is formed without compaction.

The solidified layer 13 is preferably formed so that its lower end surface 13a is at a position deeper by 10 cm or more from the pile head surface 22a of each ready-made pile 21. Further, the strength and the thickness dimension of the solidified layer 13 are determined so as to secure the integrity of the ready-made pile 21 and the solidified layer 13 and to have the performance required to reduce the settlement of the soft ground 11. It

A roadbed material such as a crusher run is laid on the solidified layer 13 thus formed, and is uniformly compacted by using a rammer or the like to form a roadbed layer 14a. And pavement layer 14b by flatly rolling it by using a road roller or the like.
To form the pavement 14, resulting in ready-made piles 21,
The embankment 12, the solidified layer 13, and the pavement 14 are integrated and constructed ((D) of the same figure).

According to the method of the present invention, by constructing the pile head 22 of the ready-made pile 21 by penetrating it into the solidified layer 13,
Since the ready-made pile 21, the embankment 12, the solidified layer 13, and the pavement 14 can be firmly integrated, the embankment 12, the solidified layer 1
3, the pavement 14, and the load of a vehicle passing on the pavement 14 is applied to the deep ground by the frictional force of each pile peripheral surface of the ready-made pile 21 and the supporting force of each pile tip, and the soft ground 11
Since it is also applied to the surface and supported by the bearing capacity of the soft ground 11, the load can be dispersed and acted not only on each of the ready-made piles 21, but it acts on the ready-made piles 21. The load burden can be reduced.

Therefore, in addition to using the ready-made piles as the pile type, the improvement rate, which is the ratio of the cross-sectional area of the ready-made piles 21 to the controlled area of one ready-made pile 21, does not exceed 10%. As a result, the number of ready-made piles 21 can be reduced and the diameter of the ready-made piles 21 can be reduced. Therefore, it is possible to prevent the shape of the surrounding ground from being deformed when the prefabricated pile 21 is driven, and the prefabricated pile 2
Since it is possible to reduce the scale of No. 1, it is possible to shorten the construction period for constructing the prefabricated piles 21, reduce the cost required for the construction, and construct roads, parking lots, etc. on soft ground. In this case, the settlement of soft ground can be reduced at low cost in a short period of time.

Further, since the embankment 12 made of high quality earth and sand with less risk of subsidence is first formed on the soft ground 11, and the ready-made piles 21 are then driven, the soft ground 11 is formed.
It is possible to place the large-sized heavy equipment for placing the ready-made piles 21 on the embankment 12 directly without placing the large-sized heavy equipment for placing the ready-made piles 21 on the ground. Therefore, the ready-made pile 21
It is possible to extremely reduce the risk of tilting or tipping over large heavy equipment in the construction work, and it is possible to perform construction with high safety.

FIG. 2 is a process explanatory view for explaining another embodiment according to the method of the present invention. Figure 2
In the case shown in, the point of forming the embankment 12A by laying good-quality earth and sand to a thickness such that the pile head 22 of the ready-made pile 21 can be seen, and the thing in which the solidifying material and the earth and sand are mixed in advance 12
It differs from the case shown in FIG. 1 in that it is laid on A to form the solidified layer 13A. Therefore, FIG.
The same reference numerals are given to the portions corresponding to the respective portions in FIG. 1 among the respective portions, and the description thereof will be omitted.

First, on the soft ground 11, a prefabricated pile to be laid after this is laid with a good quality earth and sand which is less likely to sink to a predetermined thickness through which the required length can be seen to form the embankment 12A (FIG. 2).
(A)). After this, the embankment 12A is equipped with various large heavy equipment for driving ready-made piles, and even if the construction work is performed, the large heavy equipment does not tilt or fall over, and the construction work of the ready-made piles can be performed safely. It has the property that it can be performed.

Next, in the embankment 12A and the soft ground 11, the prefabricated piles 21 are projected from the embankment 12A of a required length and driven to a required depth at predetermined intervals (FIG. 2 (B)). Ready-made pile 21
After laying, the powder or slurry of cement, cement solidifying material, solidified material such as quick lime, and earth and sand are laid on the embankment 12A and ready-made piles 21 and hardened to solidify the solidified layer 13A. Are formed (FIG. 2 (C)).

The solidified layer 13A has a lower end surface 13
It is desirable that Aa is formed at a position deeper than 10 cm from each pile head surface 22a of the ready-made pile 21. Further, the strength and the thickness dimension of the solidified layer 13A are determined so as to secure the integrity of the ready-made pile 21 and the solidified layer 13A and to have the performance required to reduce the settlement of the soft ground 11. ing.

After the solidified layer 13A is formed, the roadbed layer 14a and the pavement layer 14b are sequentially laid on the solidified layer 13A to form the pavement 14 as in the case shown in FIG. 1 (D). The pile 21, the embankment 12A, the solidified layer 13A, and the pavement 14 are integrated and constructed (FIG. 2D).

According to the method of the present embodiment, the same effect as in the case shown in FIG. 1 can be obtained, and a mixture of earth and sand and a solidifying material is laid on the embankment 12A to solidify the solidified layer 13A.
Since it was designed to form a
It is not necessary to mix the solidifying material and the earth and sand while paying attention to the depth dimension of A, and the solidifying material and the earth and sand can be easily and evenly mixed, so that the expected performance of the solidified layer 13A can be obtained. It is possible to improve the work efficiency and simplify the work at the construction site.

FIG. 3 is a process explanatory view for explaining another embodiment according to the method of the present invention. Figure 3
In the case shown in, the excavated surface 11 obtained by excavating the soft ground 11 is
The point that the embankment 12B is formed on a is different from the case shown in FIG. Therefore, of the parts of FIG. 3, those parts corresponding to the parts of FIG. 1 are designated by the same reference numerals, and a description thereof will be omitted.

First, the soft ground 11 is excavated to a depth L of a required dimension, and good quality earth and sand is laid on the excavation surface 11a to a predetermined thickness so that ready-made piles to be subsequently placed are buried. Then, the embankment 12B is formed (FIGS. 3A and 3B). The embankment 12B has a property that after this, various large heavy equipment for placing ready-made piles is placed, and the large heavy equipment does not tilt or fall over even when performing the construction work, and the construction can be performed safely. have.

Next, the prefabricated piles 21 are driven to the predetermined depth in the embankment 12B and the soft ground 11 at a predetermined interval (FIG. 3).
(C)). At this time, each pile head surface 22a of the prefabricated pile 21 is covered with earth and sand of a predetermined depth in the embankment 12B, and the pile head 22 is embedded.

The ready-made pile 21 which is the upper layer portion of the embankment 12B
In the thickness portion to the depth position below the pile head surface 22a of
Powder or slurry-like cement, cement solidifying material, solidifying material such as quick lime are mixed and hardened to form a solidified layer 13B (FIG. 3 (D)). Depending on the water content of the embankment 12, it may be compacted after mixing to form the solidified layer 13B or may be formed without compaction. The lower end surface 13Ba of the solidified layer 13B is 10 to 10 from the pile head surface 22a of each ready-made pile 21.
It is desirable to be formed at a position deeper than cm.

After the solidified layer 13B is formed, FIG.
Similar to the case shown in FIG. 5, the roadbed layer 14a and the pavement layer 14b are laid to form the pavement 14, and the ready-made pile 21, the embankment 12B, the solidified layer 13B, and the pavement 14 are integrally formed.

According to the method of this embodiment, the same effect as that shown in FIG. 1 can be obtained, and the soft ground 11 is first excavated to a required depth L, and the excavation surface 11a formed by excavation is formed. Since the embankment 12B, the solidified layer 13B, and the pavement 14 have been constructed, it is possible to finish the level position LV of the surface of the pavement 14 to be substantially the same height as the level position LV of the original surface of the soft ground 11. For this reason, for example, it is possible to finish the adjoining site where the pavement 14 is not formed, at approximately the same height level and without a step, so that the road where the pavement 14 is formed and the adjoining site where the pavement 14 is not formed are provided. It is possible to build roads that are easy for people and vehicles to come and go.

Further, in the case shown in FIG. 3, the finishing level position of the pavement 14 is finished to be substantially the same height as the level position of the original surface of the soft ground 11, but the depth L
Can be set to an appropriate depth and the surface of the pavement 14 can be finished at a desired level position.

In the method of this embodiment, the solidified layer 13B is formed by mixing the solidifying material in the upper layer portion of the embankment 12B laid on the soft ground 11, but the embankment 12B is prepared as a ready-made pile 21.
The pile head 22 may be constructed to have a thickness that allows a desired length to be seen, and a mixture of a solidifying material and earth and sand may be laid on the embankment 12B to form a solidified layer. Also at this time, the lower end surface of the solidified layer is more than 1 mm from the pile head surface 22a of the ready-made pile 21.
It is desirable to be formed at a position deeper than 0 cm.

FIG. 4 is a process explanatory view for explaining still another embodiment according to the method of the present invention. In the case shown in FIG. 4, the pile head surface 22a of the ready-made pile 21.
Is different from the case shown in FIG. 1 in that it is constructed so as to have substantially the same height level as the lower end surface 13Ca of the solidified layer 13C. Therefore, of the parts of FIG. 4, those parts corresponding to the parts of FIG. 1 are designated by the same reference numerals, and a description thereof will be omitted.

First, high-quality earth and sand with less risk of subsidence is laid on the soft ground 11 to a predetermined thickness to form the embankment 12C (FIG. 4 (A)). The embankment 12C has a property that after this, various large-sized heavy equipment for placing ready-made piles is placed, and the large-sized heavy equipment does not tilt or fall over even if the construction work is performed, and the construction can be performed safely. have.

Next, the ready-made piles 21 are driven by a required number of piles at a predetermined interval to a required depth (FIG. 4 (B)). At this time, the pile head surface 22a of the ready-made pile 21 is covered with earth and sand of a predetermined depth in the embankment 12C, and each pile head 22 is embedded.

On the pile head surface 22a of the ready-made pile 21 and on the upper layer portion of the embankment 12C, powder or slurry cement,
A solidifying material such as cement solidifying material or quick lime is mixed and hardened to form a solidified layer 13C (FIG. 4C). Ready-made pile 21
The pile head 22 of is just hidden and buried in the embankment 12C, the lower end surface 13Ca of the solidified layer 13C contacts the pile head surface 22a of each ready-made pile 21, and the solidified layer 13C is formed on the ready-made pile 21. It

After the solidified layer 13C is formed, FIG.
Similar to the case shown in Fig. 4, the roadbed layer 14a and the pavement layer 14b are laid to form the pavement 14, whereby the ready-made piles 21, the embankment 12C, the solidified layer 13C, and the pavement 14 are integrally constructed (Fig. 4). (D)).

According to the method of this embodiment, substantially the same effect as that shown in FIG. 1 can be obtained, and the pile head 2 of the ready-made pile 21 can be obtained.
The solidifying material can be mixed with the embankment 12C in a state where 2 does not protrude from the embankment 12C, that is, the solidifying material can be mixed with the embankment 12C without avoiding the pile heads 22 when forming the solidified layer 13C. Therefore, without paying attention to avoid the pile head 22, it is possible to shorten the time required for the work of forming the solidified layer 13C, improve the work efficiency, and reduce the settlement of the soft ground 11. Construction can be performed.

[0044]

According to the method of the present invention, as described above,
First, lay good quality earth and sand with less risk of subsidence on soft ground to form embankment, place ready-made piles in the embankment and soft ground, and insert the pile heads of ready-made piles 10 cm or more. A solidified layer is formed on the embankment and the prefabricated pile, and pavement is constructed on the solidified layer to integrate the prefabricated pile, the embankment, the solidified layer, and the pavement, and the embankment, the solidified layer, and the pavement on the soft ground. And other vehicles, etc. are transmitted from the peripheral surface and the tip of the prefabricated pile to the deep ground of the soft ground and also directly to the soft ground surface through the embankment, so only the prefabricated pile is loaded. Since the load is dispersed and applied without burdening the load, it is possible to reduce the load of the load applied to the ready-made pile. Therefore, it is possible to prevent the improvement rate, which is the ratio of the cross-sectional area of the pile to the controlled area of one pile, from exceeding 10%, thereby preventing the shape of the surrounding ground from being deformed when the columnar body is constructed. Besides, it is possible to reduce the number of ready-made piles to be laid, and / or to reduce the pile diameter to shorten the construction period and reduce the construction cost. As a result, when constructing a road, a parking lot, or the like on the soft ground, it is possible to perform construction for reducing the subsidence of the soft ground at low cost in a short period of time.

In order to form an embankment by laying good quality earth and sand which is unlikely to sink, on the soft ground, various large heavy machines for driving ready-made piles are not brought directly onto the soft ground, Since large heavy equipment is installed on the embankment consisting of earth and sand and ready-made piles are placed, it is possible to install large heavy equipment in a stable and safe posture and perform placement work, while maintaining construction safety. Construction work can be performed to reduce the settlement of soft ground.

[Brief description of drawings]

FIG. 1 is a process explanatory view for explaining an example of an embodiment for reducing subsidence of soft ground by the method of the present invention.

FIG. 2 is a process explanatory view for explaining another embodiment according to the method of the present invention.

FIG. 3 is a process explanatory view for explaining another embodiment according to the method of the present invention.

FIG. 4 is a process explanatory view for explaining still another embodiment according to the method of the present invention.

[Explanation of symbols]

11 soft ground 12, 12A, 12B, 12C Embankment 13, 13A, 13B, 13C Solidified layer 13a, 13Aa, 13Ba, 13Ca Lower end surface 14 pavement 21 Ready-made piles 22 pile head 22a Pile head surface

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kunihiko Oumi             1-25-1 Nishi-Shinjuku, Shinjuku-ku, Tokyo Taisei             Construction Co., Ltd. (72) Inventor Yasuo Ito             1-25-1 Nishi-Shinjuku, Shinjuku-ku, Tokyo Taisei             Construction Co., Ltd. F-term (reference) 2D040 AA02 AB07 AB11 AC05 CA01                       CA03 CB01 CB03                 2D043 CA01 CA08                 2D046 DA17

Claims (7)

[Claims] 1. A method for reducing the settlement of soft ground using ready-made piles, which comprises first laying a good quality earth and sand which is unlikely to sink on the soft ground to form a fill, and forming the fill and the soft ground. Placing the ready-made pile, forming a solidified layer on the embankment and the ready-made pile, constructing a pavement on the solidified layer to the ready-made pile, the embankment, the solidified layer and the pavement. Integrate, and transfer the load of the embankment, the solidified layer, the pavement, and other vehicles applied on the soft ground to the deep ground of the soft ground from the peripheral surface and the tip of the ready-made pile. A subsidence reduction method for soft ground, which is characterized in that it is transmitted directly to the soft ground surface via a bank. 2. The method for reducing settlement of soft ground according to claim 1, wherein the pile head of the ready-made pile is allowed to penetrate into the solidified layer. 3. The pile head of the ready-made pile is placed in the solidified layer.
The method of reducing subsidence of soft ground according to claim 1, wherein the penetration is made 0 cm or more. 4. The settlement reduction method for soft ground according to claim 1, 2 or 3, wherein an improvement rate, which is a ratio of a cross-sectional area of the ready-made pile to a controlled area of one of the ready-made pile, does not exceed 10%. 5. The method of reducing subsidence of soft ground according to claim 1, 2, 3 or 4, wherein the solidified layer is constructed by mixing a solidifying material in an upper layer portion of the embankment. 6. The method for reducing subsidence of soft ground according to claim 1, 2, 3 or 4, wherein a mixture of earth and sand and a solidifying material is laid on the embankment to construct the solidified layer. 7. The embankment is formed on an excavated surface obtained by excavating the soft ground to a predetermined depth.
The method for reducing subsidence of soft ground according to 3, 4, 5 or 6.