KR20070103655A - Method for fortifying supporting force of weak land and device for fortifying supporting force of weak land having geotextile installed on piles - Google Patents

Abstract

A method for enhancing bearing capacity of the soft ground is provided to support axial load, lateral flow pressure or transverse load by installing geotextiles on the upper part of piles. A method for enhancing bearing capacity of the soft ground comprises the steps of: spreading a first sand mat layer(30) on the upper part of the soft ground(10), and installing a plurality of piles(20) to make the front end of the piles in contact with a bearing layer(11) through the sand mat layer and the soft ground using a pile driving device(100); installing support plates(21) having a larger size than the head of the pile to a head of each pile to extend the contact area with geotextiles(40); spreading geotextiles for transferring load to piles on the upper part of the piles and connecting the heads of the piles with geotextiles; and spreading a second sand mat layer(50) on the upper part of the geotextiles and banking up on the upper part of the second sand mat layer.

Description

TECHNICAL FOR FORTIFYING SUPPORTING FORCE OF WEAK LAND AND DEVICE FOR FORTIFYING SUPPORTING FORCE OF WEAK LAND HAVING GEOTEXTILE INSTALLED ON PILES}

1 is an explanatory view of a state constructed by a method of strengthening the bearing capacity of a soft ground using a conventional geotextile pack and compaction pile

2 is an explanatory diagram of a state constructed by the soft ground reinforcement method according to the present invention

Figure 3 is a view illustrating a state in which the soft ground bearing capacity reinforcing device is installed in accordance with the present invention to distribute the load

4 is an explanatory diagram showing a state in which a load is transmitted to a pile in a state in which a soft ground support force reinforcing device is installed according to the present invention;

Figure 5 (a) to Figure 5 (e) is a construction flowchart illustrating a method for strengthening the bearing capacity of the soft ground according to the present invention

Figure 6 (a) and Figure 6 (b) is an embodiment of the fixed form of the pile head and the support plate in the device for strengthening the bearing capacity of the soft ground according to the present invention

<Explanation of symbols for main parts of the drawings>

1 Soft ground 2 Geotextile Pack

3 Filler 4 Upper Mat Reinforcement

5 Fill 10 Soft Ground

11 support layer 20 pile

21 Support Plate 30 First Sand Mat Layer

40 Geotextile 50 2nd Sand Mat Layer

60 Fill 70 Structure

Registered Utility Model Publication No. 20-292926, Strengthening System of Soft Ground Using Compaction Pile Reinforced by Geotextile Pack

The present invention relates to a method for reinforcing bearing capacity of soft ground and a soft ground bearing reinforcing device including a geotextile installed in the pile head. More particularly, the present invention relates to a method and an apparatus for strengthening the bearing capacity of a soft ground to install a geotextile on top of a pile to support lateral load as well as lateral flow pressure or transverse load.

In general, as a method of improving the soft ground, by applying embankment load to the ground where vertical drainage materials such as PBD, sand drain, and pack drain are installed, it promotes consolidation to increase the strength of the ground, and stone column or sand compaction pile The method of substituting the ground is known. The sand compaction pile is also used as a vertical drainage method, and is also used as a replacement method at the base of the coastal harbor facility.

Until now, most of the methods for improving the soft ground have been generally used to preload the ground in which the vertical drainage is installed to promote consolidation drainage. Increasing the strength of the soft ground, however, does not completely avoid damage to the structure and generation of subfrictional forces due to long-term consolidation or secondary compression. Even if the consolidation drainage method increases the strength of the ground, a foundation system should be introduced to prevent the destruction of the ground in case of high fill load or structural load.

Sand compaction pile used as a substitution method is already widely used. Korean Utility Model Registration No. 20-292926 discloses a method for increasing the bearing capacity of soft ground using compacted piles reinforced with geotextile packs. BRIEF DESCRIPTION OF THE DRAWINGS It is a figure for demonstrating the state constructed by the construction method disclosed by the said document. Referring to FIG. 1, first, a steel pipe is pressed into a soft ground (1), and then a filler (3) such as gravel, sand, and crushed stone is packed into a pack (2) reinforced with high-strength geogrid. ) After installing sand and install the mat reinforcement (4) installed in a constant surface. It is part of the Geotextile Coated Column (GCC) method which supports the fill load (5) in the soft ground disclosed in the above document with a geotextile wrapped column. This method is to construct a composite ground with increased shear strength by replacing part of the soft ground with sand and gravel columns. For more efficient ground substitution, it is necessary to prevent the breaking and narrowing of the cross section of the large diameter stone column. The method disclosed in the above document improves the quality of the stone column by filling a sand, gravel, etc. by making a pack with high-strength geotextiles 2.

However, there is a problem in that the support mechanism of the ground reinforced by the stone column made of the geotextile 2 and the filler 3 formed by the method disclosed in the above document cannot be clearly identified. Where stone columns are used to support the loads of the structure, the bearing capacity in the vertical direction shall be assumed to be the mixed ground of the stone columns and the unreinforced soft ground. In order to verify the actual bearing capacity, a large plate load test should be carried out on an area containing a large number of stone columns and soft ground. In addition, the stone column reinforced with high-strength geosynthetic fiber is not a continuous element, it is not possible to grasp clear engineering properties. That is, the homogeneous and isotropic or anisotropic properties of the material of the continuum object cannot be clearly identified.

In addition, when the stone column is subjected to the transverse load, since the material is discrete, it is difficult to predict what the transverse support behavior will be, and it is not possible to calculate the flexural rigidity in engineering. Therefore, the vertical load such as embankment load can be supported by increasing the strength of the mixed ground, but there is a problem that it is difficult to reflect the support mechanism in the design for the lateral flow pressure and the lateral load of the structure.

An object of the present invention is to provide a method and a reinforcing device for reinforcing the soft ground, which can predict the support mechanism not only for the vertical load but also for the lateral flow pressure and the lateral load when the reinforcing force for the soft ground is to be reinforced.

The method of reinforcing the bearing capacity of the soft ground according to the present invention is to reinforce the bearing capacity of the soft ground economically and effectively by using piles and geotextiles for the large area embankment load or the load of the structure constructed on the soft ground.

In general, in order to support a load through the pile, a slab, a cap, or a footing that connects the pile and the pile is required. When the slab is connected to the head of the pile, deflection occurs due to the slab weight and the fill load or the load of the structure. Since the moment generated by this deflection causes the member to break, the slab must have a bending force and a member force capable of resisting shear. Therefore, the wider the spacing of piles supporting the load or structure load, the greater the deflection and the thicker the slab to withstand the member force.

The method of reinforcing the bearing capacity of the soft ground according to the present invention uses a high-strength geosynthetic fiber, rather than a concrete slab as a medium for transferring the fill load or the load of the structure to the pile. In soft ground that is not supported by piles, settlement occurs due to the upper load. When geotextiles are installed on top of the piles to connect the heads of each pile to the geotextiles, the upper loads acting between the piles are transferred to the geotextiles, and the upper loads are supported by the tensile strength of the geotextiles. Tensile force applied to the geosynthetic fiber is transferred to the pile head, so that the load of the fill and the structure is perfectly supported through the pile as long as the supporting force of the pile is secured.

According to one aspect of the invention, there is provided a method for strengthening the bearing capacity of soft ground. The method of strengthening the bearing capacity of the soft ground according to the present invention comprises the steps of: laying a first sand mat layer on top of the soft ground, and a plurality of piles so that the tip of the pile penetrates the sand mat layer and the soft ground layer to reach the supporting layer. And installing the geotextiles for transferring the load on top of the plurality of piles and connecting the heads of the plurality of piles with the geotextiles. It is preferable to use ready-made piles (RC, PC, PHC) as the pile, but it is also possible to use on-site casting piles.

In the present invention, between the step of installing a plurality of piles and connecting the head of the plurality of piles to the geosynthetic fibers, at least one of the plurality of piles in the head of the pile to expand the contact area with the geosynthetic piles It is preferable to further include the step of installing a support plate having an area larger than the head of the.

In addition, it is possible to connect the head of the pile with geosynthetic fibers and directly construct or fill the slab of the structure on the top of the geosynthetic fiber. have.

At this time, the support plate is bolted to the head of the pile, or polygonal groove is formed on the head of the pile, and a polygonal protrusion is formed on the lower surface of the support plate to insert and fix the protrusion of the support plate into the groove, or by using an adhesive Adhesion can also be fixed.

According to another aspect of the present invention, there is provided a device for strengthening the bearing capacity of a soft ground comprising a pile and geotextiles. A device for reinforcing support of soft ground according to the present invention includes a plurality of piles installed so as to reach the support layer through the first sand mat layer and the soft ground disposed on the soft ground, and evenly load the plurality of piles. It characterized in that it comprises a geotextile laid on top of the plurality of piles for delivery.

In addition, it is preferable to fix the support plate having a larger area than the head of the pile fixed to the head of at least one of the plurality of piles in order to enlarge the contact area with the geosynthetic fiber.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the present invention.

5 (a) to 5 (e) is a construction flowchart illustrating a method for strengthening the bearing capacity of the soft ground according to the present invention. First, the first sand mat layer 30 is disposed on the soft ground 10, and the tip of the pile 20 penetrates through the sand mat layer 30 and the soft ground layer 10 to the support layer 11. A plurality of piles to be installed using the pile construction equipment 100 (Fig. 5 (a) and 5 (b)). As the pile 20, ready-made piles such as RC, PC, PHC and composite piles, or can be used in the field cast. In addition, the grouting column, which is to be used for piles, can also be used because of its large effective diameter. When the pile is installed, the tip of the pile 20 is inserted into the support layer 11 to secure a supporting force to support the fill load. Next, a support plate 21 having a larger area than the head of the pile is installed on the head of each pile 20 so that the contact area with the geosynthetic fiber 40 is enlarged (FIG. 5C). Next, the geosynthetic fiber 40 for transferring the load to the pile is installed on the upper portion of the plurality of piles 20 to connect the head of the plurality of piles with the geosynthetic fiber (Fig. 5 (d)). High-strength geotextiles should have different strength depending on the size of the upper load, and are designed to support the upper load in consideration of pile spacing. Next, a second sand mat layer 50 is laid on the top of the geotextile 40, and then buried in the top of the second sand mat layer 50 (FIG. 5 (e)). The second sand mat layer 50 is disposed on the upper portion 40 and the fill 60 is applied, but the floor slab of the structure 70 may be directly constructed.

2 to 4, the soft ground 10 that is not supported by the pile 20 due to the load of the fill soil 60 or the structure 70 dropped on the top of the geosynthetic fiber 40 is settled. . However, the load F of the fill 60 or the structure 70 loaded on top of the geotextiles is supported by geotextiles having a high tensile strength. In addition, the tensile force (T) applied to the geosynthetic fiber is transmitted to the pile through the support plate 21 installed on the head of the pile 20, the tip of the pile is supported by the support layer 11, so the soft ground 10 Even if settled, the top layer 60 or the structure 70 is supported by the geotextiles. Since the pile 20 is a continuum, it can be used to reinforce the bearing capacity of the soft ground inexpensively and effectively by reflecting the known physical properties of the lateral load or flow pressure as well as the vertical load. In addition, when the soft ground is settled using the geosynthetic fiber 40 having a high tensile strength, the load applied to the pile layer 60 or the structure 70 can be transferred to the pile 20, so the ground is settled by the settlement of the soft ground. Prevents layer 60 or structure 70 from collapsing.

6 shows a fixed coupling structure of the head and the support plate of the pile 20. Referring to Figure 6 (a), the head of the pile is formed with a groove 23 having a rectangular cross section, a projection 22 having a rectangular cross section is formed on the lower surface of the support plate 21. When the projection 22 of the support plate 21 is inserted into the groove 23, the support plate is applied to the geosynthetic fibers installed on the upper part is to act only from the top to the bottom so that the plate does not rotate or deviate. Referring to Figure 6 (b), the support plate is fixed by fastening the bolt to the head of the pile. Although not shown, an insert for bolting when the pile is placed is inserted into the head end surface of the pile.

According to the present invention, in order to reinforce the supporting force of the soft ground, it is possible to provide a method and reinforcing device for reinforcing the soft ground, which can predict the supporting mechanism for not only the vertical load but also the lateral flow pressure and the lateral load.

The method of strengthening the bearing capacity of the soft ground according to the present invention has the following useful effects in industry.

First, it is possible to stably support the fill load through the pile or grouting column constructed on the sand mat layer. Since piles and grouting columns are homogeneous and continuous, the engineering properties can be easily understood, and the basic behavior of the reinforced soft fats in terms of vertical load, lateral load and moment can be easily calculated.

Secondly, even if the gap between the piles is wide, the earth load or structural load is transmitted to the geotextile, and if the transmitted load is within the tensile strength of the geotextile, the top load can be stably supported.

Third, because the connections between piles are made of high-strength geosynthetics rather than concrete slabs, it is not necessary to reinforce the member forces against moments caused by sag due to the slab's own weight or upper load.

Fourth, when the upper load is applied to the high-strength geosynthetic fiber and the deflection occurs to a certain degree, the tensile force of the geosynthetic fiber is transferred to the head of the pile, applying a force to the pile in the form of a vertical load. Therefore, even if the gap between piles is wide enough, if the tensile strength of the geosynthetic fiber and the pile strength are sufficiently designed, it is possible to economically and stably support the fill load and the load of the structure.

An embodiment of the present invention described above and illustrated in the drawings should not be construed as limiting the technical spirit of the present invention. The protection scope of the present invention is limited only by the matters described in the claims, and those skilled in the art can change and change the technical idea of the present invention in various forms. Therefore, such improvements and modifications will fall within the protection scope of the present invention, as will be apparent to those skilled in the art.

Claims (9)

Laying a first sand mat layer on top of the soft ground; Installing a plurality of piles such that the tip of the pile penetrates through the sand mat layer and the soft ground layer to contact the support layer; Method of strengthening the bearing capacity of the soft ground, comprising the step of installing the geosynthetic fiber for transmitting the load on top of the plurality of piles to connect the head of the plurality of piles with geosynthetic fibers. The method of claim 1, Between installing the plurality of piles and connecting the heads of the plurality of piles with geosynthetic fibers, an area larger than the head of the piles to enlarge the contact area with the geosynthetic fibers on the head of at least one of the plurality of piles. Supporting method of strengthening the soft ground, characterized in that it further comprises the step of installing a support plate having. The method of claim 2, The support plate is strengthening the bearing capacity of the soft ground, characterized in that the bolt is fixed to the head of the plurality of piles. The method of claim 2, A groove is formed in the head of the pile, and a protrusion is formed in the lower surface of the support plate, and the support plate is soft, characterized in that a protrusion formed in the lower surface is inserted into and fixed in the groove formed in the head of the pile. How to strengthen the bearing capacity of the ground. The method according to any one of claims 1 to 4, After connecting the head of the pile with the geosynthetic fiber, further comprising the step of laying a second sand mat layer on the top of the geosynthetic support method for strengthening the soft ground. A plurality of piles installed through the first sand mat layer and the soft ground disposed on the soft ground to reach the support layer; Reinforcement device of the soft ground, characterized in that it comprises a geotextile installed on top of the plurality of piles to evenly distribute the load to the plurality of piles. The method of claim 6, And a support plate having a larger area than the head of the pile fixed to the head of at least one of the plurality of piles to enlarge the contact area with the geotextiles. The method of claim 7, wherein The support plate is strengthening device of the soft ground, characterized in that the bolt is fixed to the head of the plurality of piles.  The method of claim 7, wherein A groove is formed in the head of the pile, and a protrusion is formed in the lower surface of the support plate, and the support plate is soft, characterized in that a protrusion formed in the lower surface is inserted into and fixed in the groove formed in the head of the pile. Ground support system.

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