KR20210065509A - Complex Method For Foundation Treatment of Soft Ground - Google Patents

Abstract

The present invention relates to a hybrid construction method for soft ground foundation treatment, capable of improving and reinforcing the quality of soft foundation ground, thereby preventing ground subsidence and inhibiting lateral deformation by securing a sufficient support force against an overburden load of a design structure. The method includes the following steps of: forming a plurality of first power-fill structures of a first depth at a first interval by injecting a rapid expandable composition through a power-fill injection pipe along the boundary of a soft ground construction area; forming a plurality of second power-fill structures of a second depth at a second interval by injecting a rapid expandable composition into the soft ground construction area through the power-fill injection pipe; and forming a raft layer in an upper part of the first and second power-fill structures of the soft ground construction area.

Description

Complex Method For Foundation Treatment of Soft Ground

The present invention relates to a complex method for treating a soft ground foundation, and more particularly, by improving and reinforcing the properties of the soft base ground to secure sufficient bearing capacity for the load of the upper structure, it is possible to prevent ground subsidence as well as , relates to a complex method for treating soft ground that can prevent lateral deformation in which the soft ground is disturbed by lateral flow.

In general, as the basic ground of structures including soil structures such as fill soil, the normal ground that has sufficient bearing capacity and does not have problems such as subsidence or lateral deformation is called ‘good ground’, and the ground that is not is ‘soft ground’.

In other words, in a broad sense, soft ground refers to the ground that does not satisfy the stability conditions of the foundation for subsidence, etc. because sufficient bearing capacity is not secured for the structure to be designed. ·It is relatively different depending on its importance, but generally refers to a soft ground composed of a high water content and high compressibility such as nitran, organic soil, unconsolidated clay, and silt, and a soil layer that is difficult to secure in relation to the load of the structure.

Quantitative criteria for determining whether the ground is soft is a cohesive soil layer with an N value of 4 or less and 10 or less in the standard penetration test (SPT Test), a test that investigates the degree of softness of the ground investigation test that investigates the soil condition of the target ground. As a result, the sandy soil layer, which is likely to be liquefied during earthquakes, is judged as soft ground.

When structures such as roads, bridges, and buildings are built directly on soft ground, the existing ground is destroyed due to insufficient bearing capacity, and consolidation or unequal subsidence of the existing ground occurs. will cause serious problems in

In order to actively improve the engineering characteristics of such soft ground, the soft ground improvement method is used, which can be divided into three main principles. That is, a substitution method that completely removes the soft soil composing the soft soil and fills it with loamy soil to improve the ground, a density increase method that lowers the water content of the soft soil or forms a solid ground through copper compaction, and a chemical method for the soft soil These include the coagulation method of improving the ground by solidifying the soft soil through treatment.

In addition, after improving the soft soil of the soft ground with the soft ground improvement method, a soft ground foundation treatment reinforcement method is also required, which reinforces the foundation of the structure built on the soft ground in order to safely construct the structure according to the design load. Concrete pile foundation method, in which concrete piles reinforce the foundation of the structure by driving concrete piles vertically up to the support layer of good ground as a treatment reinforcement method. Mat that reinforces the foundation by laying geotextile mats such as mesh nets on the soft ground, filling sand between them, and compacting them The construction method, the top-base construction method of installing a top-shaped concrete pile, etc. are being used.

On the other hand, the present applicant has proposed the Republic of Korea Patent Application No. 10-2017-0022156 'Soft ground improvement method using high-density polyurethane' as one of the methods for improving soft ground in ultra-soft ground.

In the above-applied invention, a soft ground improvement method comprising the following steps is disclosed.

a. Inserting an injection tube having a tube made of a waterproof material at the bottom into an injection hole formed by a perforator

b. Forming a foundation pile by injecting the instantaneous expansion composition with air through the injection tube

c. After compacting by installing solidified soil on the upper part of the foundation pile, the step of installing the solidified soil mat by installing geotextiles

d. After laying the substitution material mixed with soft soil and solidified soil on the top of the solidified soil mat, laying the geotextile to construct the replacement layer

e. After laying crushed stone on the top of the replacement layer, installing a conical pile

f. After filling crushed stone around the conical pile, constructing a finishing layer with discarded concrete on top

The above-applied invention is a foundation pile made of high-density polyurethane, an eco-friendly material, instead of the cement-based stabilizing solidifying agent, which has been widely used for the improvement of the conventional soft ground, and constructing the upper part with a solidified soil mat and a conical pile. It aims to provide a soft ground improvement method that can secure constructability, economic feasibility and environmental performance as well as stability against increase and subsidence.

However, the invention applied above is configured to construct a foundation pile at a uniform depth and spacing throughout the site construction area, so it can only serve to assist the basic bearing capacity of the structure, and can be used as a continuous underground wall or order wall. There was a problem that the role could not be performed properly.

In addition, the claimed invention is configured to construct a solidified soil mat layer, a replacement layer, and a conical pile on the upper part of the foundation pile through several steps, which is used in a construction method of forming an underground wall using the existing solidified soil As a simple borrowing of the old method, there was a problem of engineering instability to apply as it is to the method using the instantaneous expansion composition.

Korean Patent Application No. 10-2009-0114078 Korean Patent Application No. 10-2011-0117437 Korean Patent Application No. 10-2017-0022156

The present invention is to solve the problems of the prior art described above, and forms a plurality of power-fill structures using polyurethane in the soft ground by using the instantaneous expansion composition, but serves as an underground wall or a power-fill structure and a foundation The purpose is to provide a complex method for treating soft ground that can effectively improve and reinforce soft ground by maximizing the securing of bearing capacity and preventing lateral deformation by forming the power fill structure that plays the role of a pile at different depths and intervals. have.

In addition, the present invention forms a new concept complex foundation in which the lower foundation is a pile foundation made of a power fill structure and the upper foundation is a raft layer made of high-strength solidified soil, thereby distributing and sharing the load of the upper structure and suppressing excessive settlement There is another object to provide a complex method for the treatment of soft ground that can be done.

The composite method for treating soft ground according to the present invention comprises the steps of forming a plurality of first power fill structures of a first depth at first intervals by injecting an instantaneous expansion composition through a power fill injection pipe along the boundary of a soft ground construction area ; Forming a plurality of second power-fill structures of a second depth at second intervals by injecting an instantaneous expansion composition through a power-fill injection pipe in a soft ground construction area; and forming a raft layer on the first power-fill structure and the second power-fill structure in the soft ground construction area.

At this time, the raft layer is composed of solidified soil formed by mixing 52 to 136 kg/m of a solidifying agent and 66 to 140 kg/m of mixed water with respect to 1,700 kg/m of soil, and the soil is gravel with good particle size, gravel with poor particle size, It is characterized in that it is any one of silt-mixed gravel, clay-mixed gravel, fine-grained sand, poor-grained sand, silt-like sand, clay-like sand, silt and clay mixed sand.

And, the solidifying agent is characterized in that it contains 40 to 60% by weight of calcined sludge powder, 18 to 24% by weight of blast furnace slag powder, 10 to 32% by weight of quicklime powder, and 3 to 10% by weight of anhydrite powder.

The raft layer is positioned between the adjacent second power fill structures and includes a load distribution unit protruding downward from a lower surface of the raft layer in an arcuate shape.

Meanwhile, two or more adjacent first power fill structures overlap each other to form a power fill band structure having a predetermined width, and a plurality of power fill band structures are formed with a first interval.

In addition, the power-fill injection tube is formed of two or more sub-power-fill injection tubes of different lengths, and the first power-fill structure is an instantaneous expansion composition injected by two or more of the plurality of sub-power-fill injection tubes. It is characterized in that it consists of two or more and a plurality of sub power fill structures.

In addition, the power-fill injection tube is composed of two or more sub-power-fill injection tubes of different lengths, and the second power-fill structure is an instantaneous expansion composition injected by two or more and a plurality of sub-power-fill injection tubes. It is characterized in that it consists of two or more and a plurality of sub power fill structures.

The present invention provides a buoyancy force on the upper raft layer by forming a first power-fill structure serving as an underground wall or an order wall along the boundary of a soft ground construction area and a second power-filling structure serving as a foundation pile in an area within the boundary of the construction area, respectively. It has the advantage of effectively preventing excessive settlement and effectively preventing lateral deformation by distributing the load of the upper structure while securing sufficient support and bearing capacity.

In addition, the present invention uses a new concept complex method in which the lower foundation forms a foundation pile with a power fill structure, and the upper foundation forms a raft layer with high-strength solidified soil, thereby constructing a foundation pile compared to the existing pile foundation method. Although the depth and number can be reduced, the stress transmitted to the ground is reduced by 1/100, and there is another advantage of reducing the maximum settlement amount and the differential settlement amount.

1 is a view showing a planar structure in which a power fill structure according to the present invention is formed in a soft ground construction area.
2 is a view showing a cross-sectional structure in which the power fill structure according to the present invention is formed in a soft ground construction area.
3 is a view for explaining a power fill structure according to the present invention.
4 is a view for explaining a power fill band structure according to the present invention.
5 is a view for explaining a raft layer according to the present invention.
6 is a view showing the test results of the ground improvement and reinforcement effect of the instantaneous expansion composition according to the present invention.
7 is a view showing the results of the neutralization experiment of the solidifying agent mortar sample according to the present invention.
8 is a view showing the plate load test result of the solidified soil sample according to the present invention.
9 is a view for explaining the Burmister stress reduction principle.

Hereinafter, specific details for carrying out the present invention will be described with reference to the accompanying drawings. In describing a specific embodiment of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted.

1 is a view showing a planar structure in which a power fill structure according to the present invention is formed in a soft ground construction area 10 .

According to FIG. 1 , a first power fill structure 110 is formed along the boundary 20 of a soft ground construction area 10 requiring improvement or reinforcement work, and a second power fill structure 120 is formed in the inner area. ) is formed.

The first power fill structure 110 is formed along the boundary 20 of the construction area, and is formed with a first gap S1 from the adjacent first power fill structure 110, the first gap S1 ) will be determined by engineering calculations considering the type of soil constituting the soft ground, the properties of the soil such as moisture content and compressibility, as well as the design load of the structure to be constructed on the upper part.

In addition, the second power fill structure 120 is formed with a second gap S2 from the adjacent second power fill structure 120 in the construction area surrounded by the first power fill structure 110 . The second interval S2 will be determined by engineering calculations in consideration of the nature of the soil constituting the soft ground and the design load of the upper structure.

In general, the first gap S1 between the first power fill structures 110 is narrower than the second gap S2 between the second power fill structures 120 , which is the first power fill structure (S1). This is because 110) is formed more densely along the boundary 20 of the soft ground construction zone, thereby suppressing lateral deformation and effectively performing the role of an underground wall or a water-order wall to block groundwater.

On the other hand, although the first power fill structure 110 is formed along all the boundaries 20 of the soft ground construction zone in FIG. 1, the ground properties of the soft ground construction zone, the design load of the upper structure and the adjacent structure, etc. It goes without saying that the first power fill structure 110 may be formed only on a portion of the boundary depending on various conditions.

In addition, although the entire first power fill structure 110 is formed at the same first interval S1 along the boundary 20 of the soft ground construction zone in FIG. 1, the shape or ground properties of the soft ground construction zone, The first power fill structure 110 may be formed at various intervals such as the 1-1 interval and the 1-2 interval according to various conditions such as the upper portion and adjacent structures.

As shown in FIG. 1 , the second power-fill structure 120 is a quadrilateral in which a plurality of second power-fill structures 120 are spaced apart from each other at a second interval S2 in an area within the boundary of the soft ground construction area 20 , as shown in FIG. 1 . It is formed in the form of a lattice, and it can be formed in various polygonal shapes such as pentagons or hexagons, or it can be formed in a random shape instead of a regular shape depending on the conditions such as the shape of the soft ground construction area, ground properties, and the shape of the upper structure. .

For example, according to the design structure of the upper structure, the second power fill structure 120 may be disposed more densely than other areas in the area receiving the eccentric load, thereby reducing the effect of the eccentric load as a whole and inducing it to act on the center of the foundation. There will be.

In the case of constructing the second power fill structure 120 in various polygonal shapes or random shapes including a grid shape, the second power fill structure 120 is not located at the same second interval S2 as a whole, but in the 2-1 interval and 2-2 interval It is natural that it can be formed at various intervals according to the

2 shows a cross-sectional structure in which the power fill structure according to the present invention is formed in the soft ground construction area 10 .

According to FIG. 2 , a first power fill structure 110 is formed on the left and right boundaries 20 of the soft ground construction zone 10 , and a plurality of second power fill structures 120 are formed at a second interval ( S2) is formed.

At this time, the first power fill structure 110 is formed at a first depth D1, and the second power fill structure 120 is formed in the soft ground construction zone 10 at a second depth D2, respectively. The first depth (D1) and the second depth (D2) will be determined by engineering calculations in consideration of the type of soil constituting the soft ground, the properties of the soil such as moisture content and compressibility, as well as the height and area of the structure to be constructed on the upper part. .

In a general case, as shown in FIG. 2 , the first power-fill structure 110 serving as an underground wall or an order wall is formed to be deeper than the second power-fill structure 120 serving as a pile foundation, but soft ground construction The first depth D1 may be formed to have a depth equal to or shorter than the second depth D2 depending on various conditions such as the shape of the zone, ground properties, upper and adjacent structures, and the like.

In addition, in the soft ground construction zone 10 , the first power fill structure 110 may be formed at various depths, such as a 1-1 depth and a 1-2 depth, as well as the second power fill structure ( 120) may also be formed in various ways, such as a 2-1 depth, a 2-2 depth, etc. as needed.

On the other hand, in (a), (b), (c) of Figure 3 is a view for explaining a method for forming a power fill structure according to the present invention is shown.

First, referring to FIG. 3( a ), first, the soft ground construction zone 10 is drilled with a drilling device (not shown in the drawing) to form the power fill injection hole 11 to the required depth and diameter.

The power-fill injection tube 300 is inserted into the power-fill injection hole 11 formed by the drilling device as described above, and the upper end of the power-fill injection tube 300 is a connecting transport member such as a hose. is not shown) and is connected.

The instantaneous expansion composition 310 supplied by the power-fill injection device is injected into the power-fill injection hole 11 through the lower end of the power-fill injection tube 300 , and the power-fill injection tube 300 is located at the lower end. In addition to the hollow of the lower end, a plurality of through holes may be formed in the side so that the instantaneous expansion composition 310 can be introduced into the power fill injection hole 11 through this.

The instantaneous expansion composition 310 injected into the power-fill injection hole 11 is solidified while applying an expansion pressure to the soft ground around the power-fill injection hole 11. As shown in FIG. 3( b ), the instantaneous expansion composition 310 is continuously added while raising the fill injection tube 300 at a predetermined time interval, and as shown in FIG. 3( b ), while applying the inflation pressure to the entire power-fill injection hole 11 , the power-fill The structure 100 is formed.

A representative example of the instantaneous expansion composition 310 forming the power fill structure 100 is polyurethane. It is preferable to use high-density polyurethane manufactured to be suitable for the method according to the present invention, not general polyurethane.

First, a polyether polyol is used as one of the compositions of high-density polyurethane. In particular, a polyether polyol using an initiator having a low molecular weight of 1300 or less having 3 or more functional groups is used.

Examples of the initiator include glycerine having a functional group of 3, pentaerythritol having a functional group of 4, diethylene triamine having a functional group of 5, sorbitol having a functional group of 6, and the like.

Another composition required to produce high-density polyurethane is isocyanate, and in this method, polymeric 4,4'-diphenylmethane diisocyanate is used.

The polymeric 4,4'-diphenylmethane diisocyanate maintains a liquid state at room temperature, has a low vapor pressure, and is not toxic, so it is a composition suitable for use when it is put into soft ground as in this method.

A foaming agent that generates bubbles is also added so that high-density polyurethane can instantaneously expand in soft ground. Conventionally, chlorofluorocarbon-based foaming agents have been widely used, but their use is currently limited due to problems such as ozone layer destruction. Cyclopentane is a typical alternative blowing agent.

When such a foaming agent is used, it is injected into the soft ground and foamed immediately due to a low boiling point when the pressure condition is changed, and the resulting high-density polyurethane foam has good mixing efficiency and has excellent physical properties.

In addition, a catalyst is added to promote the resinization reaction and foaming reaction, such as TEDA (Triethylene Diamine), DMEA (Dimethyl Ethanol Amine), TMBDA (Tetramethyl Butane Diamine), DMCHA (Dimethyl Cyclohexyl Amine), TEA (Triethyl Amine), etc. It is preferable to use an amine-based catalyst, and although an organometallic salt catalyst may be used in combination, those that may cause soil contamination should be excluded.

The power fill structure 100 formed by the polyurethane-based instantaneous expansion composition made of the above-described composition fills the gaps and voids by applying pressure to the soft ground while instantaneously expanding, and as can be seen from the experimental results of FIG. 6 , the power fill structure 100 expands. The pressure reaches 50~100ton/m2, and the expansion volume reaches 15~30 times the input amount.

The polyurethane-based instantaneous expansion composition made of the above-described composition has excellent expansibility as well as resistance to fresh water, seawater, oil, etc. and excellent durability, so it is very suitable as a material for forming an eco-friendly power fill structure.

On the other hand, even if the instantaneous expansion composition is injected into the power fill injection hole 11 as it is, it expands at a fast rate and solidifies to maintain a constant shape, but after inserting a flexible tube or the like into the power fill injection hole 11 first It may be configured to expand together with the tube by injecting the instantaneous expansion composition into the tube.

3( c ) shows a power-fill structure formed in a soft ground using three sub-power-fill injection pipes.

In this case, the power-fill injection tube 300 is composed of first to third sub-power-fill injection tubes 301 , 302 , and 303 of different lengths, respectively, and the instantaneous expansion composition supplied from the power-fill injection device is supplied from the first to third sub-power-fill injection tubes. The three sub power fill injection tubes 301 , 302 , and 303 were allowed to be simultaneously injected into the upper, middle, and lower portions of the power fill injection hole 11 .

That is, the instantaneous expansion composition injected through the first sub-power-fill injection tube 301 forms the first sub-power-fill structure 101 on the upper portion of the power-fill injection hole 11 and the second sub-power-fill injection tube 302 . The instantaneous expansion composition injected through the second sub power fill structure 102 in the central portion of the power fill injection hole 11, and the instantaneous expansion composition injected through the third sub power fill injection tube 303 is the power fill injection hole (11) The third sub power fill structures 103 are respectively formed in the lower portion.

In this way, the power-fill structure 100 is formed by dividing the power-fill structure 100 into the first to third sub-power-fill structures 101 , 102 , and 103 , thereby forming the power-fill structure 100 with one power-fill injection tube 300 . Not only can the construction time be reduced, but also, since each of the sub power fill structures 101 , 102 , 103 expands and solidifies at the same time, there is an advantage that an even expansion pressure can be applied to the soft ground.

In addition, the first to third sub power-fill injection tubes 301 , 302 , 303 inserted into the power-fill injection hole 11 are left in the power-fill injection hole 11 without being removed even after all the instantaneous expansion composition is injected. It can be put to solidify together with the instantaneous expansion composition.

The first to third sub-power-fill injection tubes 301 , 302 , and 303 integrated with the power-fill structure serve as pillars in the power-fill structure, and the raft layer 200 and the power-fill structure 100 are formed thereon. will connect

On the other hand, although it is shown in FIG. 3(c) that three sub-power-fill structures are formed with three sub-power-fill injection tubes, the two sub-power-fill structures are formed according to various conditions such as the depth of the power-fill injection hole 11 or the nature of the soft ground. Of course, it may be composed of four sub-power-fill injection tubes or four or more sub-power-fill injection tubes.

4 shows a power-fill band structure in which three power-fill structures are continuously formed and overlap each other.

As described above, one power-fill structure is formed in the soft ground with a first interval S1 or a second interval S2 from the adjacent power-fill structure. However, the first power fill structure 110 serving as an underground wall or an order wall may be configured as a power fill band structure as shown in FIG. 4 in order to more faithfully serve as an underground wall or an order wall.

That is, three power fill injection holes 11 are adjacently formed in the soft ground, and then three power fill injection tubes are inserted into each power fill injection hole 11, and then three power fill injection holes are simultaneously formed. to form a structure.

As described above, the three power-fill structures formed in the three adjacent power-fill injection holes 11 overlap each other while expanding, and the three power-fill structures form one power-fill band structure to serve as an underground wall or an order wall. will do

In this case, the power-fill structure 100 may be formed by inserting one power-fill injection tube 300 into each of the three power-fill injection holes 11 , but each power fill structure 100 may be formed using the method of FIG. 3( c ). Three sub-power-fill injection tubes may be inserted into the fill injection hole 11 to form three sub-power-fill structures.

That is, as shown in FIG. 4 , the first to third sub-power-fill structures 101a , 102a and 103a are formed in the left power-fill injection hole 11 , and the first to third sub-power-fill structures are also formed in the central power-fill injection hole 11 . to third sub power-fill structures 101b, 102b, and 103b are formed, and first to third sub-power-fill structures 101c, 102c, and 103c are formed in the right power-fill injection hole 11 to form each adjacent sub-power-fill structure As the power fill structure expands, it overlaps, and as a result, a total of nine sub power fill structures form one power fill band structure.

A total of nine sub-power-fill injection tubes used to form each sub-power-fill structure are left as they are without being removed as described above to serve as a pillar connecting the upper raft layer 200 and the power-fill structure.

Meanwhile, although FIG. 4 shows that three power-fill injection holes are adjacent to each other to form a power-fill band structure, two power-fill injection holes or four or more power-fill injection holes are shown depending on the nature of the soft ground or various conditions such as the upper structure. The injection holes may be adjacent to each other to form a power fill band structure.

After forming the first power-fill structure 110 and the second power-fill structure 120 in the soft ground construction zone as described above, a raft layer 200 of a certain thickness is formed thereon, the raft layer 200 Use high-strength solidified soil blended at a ratio of 51~136kg/m3 of solidifying agent and 66~140kg/m3 of mixed water to 1,700kg/m3 of silver soil.

At this time, as the solidified soil, soil generated by excavation at the construction site may be used, but if there is a quality problem, high-quality soil should be brought in from the outside and used, and soil containing excessive organic impurities or chlorides should be used. refrain from using it.

That is, according to the standard soil classification, fine-grained gravel, poor-grained gravel, silt-mixed gravel, clay-mixed gravel, fine-grained sand, poor-grained sand, silty sand, clay sand, silt and clay mixed sand, etc. can be used as solidified soil materials. There will be.

Conventionally, cement has been mainly used as a solidifying agent that forms the solidified soil together with the soil, but in recent years, due to the toxic substances contained in cement, when used as a solidifying agent, the need to replace it is greatly increased due to the problem of contamination of the soil. .

Accordingly, the present invention proposes an environmentally friendly solidifying agent that recycles inorganic components generated in various industrial sites to prevent soil contamination and to be sufficiently used in soft ground containing a lot of moisture.

Specifically, the solidifying agent according to the present invention comprises 40 to 60% by weight of calcined sludge powder, 18 to 24% by weight of blast furnace slag powder, 10 to 32% by weight of quicklime powder, and 3 to 10% by weight of anhydrous gypsum powder. A coagulant or the like may be further added.

The calcined sludge powder can be obtained by incinerating or calcining sludge generated in various industrial sites. In particular, the paper sludge generated in a paper mill that manufactures paper contains many inorganic components in addition to pulp, and through the calcination process, pulp, etc. Organic components are burned and only inorganic components remain, which can be used as a good raw material for a solidifying agent.

Blast furnace slag is generated as a by-product in the process of manufacturing pig iron by melting iron ore together with coke in a blast furnace. It contains silicon dioxide (SiO ₂ ), aluminum oxide (Al ₂ O ₃ ), and iron oxide (Fe ₂ O ₂ ). In addition, the blast furnace slag should be finely powdered to a powder of 6000 cm2/g or more.

Quicklime powder should be added to make up for the insufficient calcium component in the solidifying agent, and anhydrous gypsum powder should be added as a solidifying agent so that the solidified soil can be hardened quickly and have high strength.

In the case of soft ground containing a lot of moisture, fly ash can be added to discharge moisture and strengthen cohesion. Fly ash is a dust collector that collects fine substances suspended in the air after the combustion of coal in a thermal power plant. .

The results of component analysis of the solidifying agent sample prepared according to an embodiment of the present invention are shown in Table 1 below, in which calcium oxide (CaO) and silicon dioxide (SiO ₂ ) are the main components, and contaminants such as hexavalent chromium are not detected. it can be seen that

Item Result Analysis Quality Si, Al, Ti, Fe, Mn, Ca, Mg, Na, K, P, S ICP & XRF Quantity SiO ₂ 30.3% KS L 3316 : 2014 Al ₂ O ₂ 12.2% TiO ₂ 0.55% Fe ₂ O ₃ 3.04% Mn ₂ O ₃ 0.12% CaO 44.1% MgO 2.84% Na ₂ O 0.63% K ₂ O 0.77% P ₂ O 0.26% SO ₃ 1.75%

On the other hand, the neutralization time of the mortar sample using the solidifying agent prepared according to an embodiment of the present invention is different from the mortar sample using general cement, as shown in FIG. 7, that the neutral value appears after about 16 days after the solidification treatment. Able to know.

The compressive strength test results of the mortar sample using the solidifying agent prepared according to an embodiment of the present invention are shown in Table 2 below, and it can be seen that the mortar sample has ten times or more strength compared to the mortar sample using general cement.

Type Result Sample Mortar 1 12.7N/㎟ Sample Mortar 2 14.8N/㎟ Sample Mortar 3 12.0N/㎟ Cement Mortar 1 0.8N/㎟ Cement Mortar 2 0.9N/㎟

On the other hand, the results of the flat plate load test of the solidified soil sample prepared by mixing the solidifying agent, the soil, and the mixed water prepared according to an embodiment of the present invention in the above-mentioned ratios are shown in FIG. 8, and the settlement ratio and prediction accordingly The yield load is as shown in Table 3 below, and it can be seen that after about 5 days of curing, the yield load is sufficient for heavy equipment to pass through.

Settlement Ratio Predicted Yield Load using Extrapolation (kPa) Day 1 Day 2 Day 3 Day 1 Day 2 Day 3 Sample 1 0.46 0.19 0.11 171 330 377 Sample 2 0.46 0.39 0.13 220 189 527

On the other hand, the above-described solidified soil may be constructed in a flat form as shown in FIG. 1 on the soft ground construction area where the first power fill structure 110 and the second power fill structure 120 are formed, As shown in FIG. 5( a ), before forming the raft layer 200 , solidified soil may be constructed after excavating between the second power fill structures 120 to a predetermined width and depth.

In this way, when the raft layer 200 is formed after excavating the soft ground in a grid form, solidified soil is also constructed in the excavated space, and as shown in FIG. 5(b), the load protruding downward from the lower surface of the raft layer (2000). The dispersion unit 210 is formed.

The shape of the load distribution unit 210 is determined depending on the type of excavation of the soft ground, and it is possible to excavate in a general groove shape so that the cross section of the load distribution unit 210 protrudes in a rectangular shape, but an ellipse It will be advantageous to structurally distribute the overhead load by excavating in a shape so that the load distribution unit 210 protrudes in an arch shape.

In addition, the depth and width excavated in the soft ground to form the load distribution unit 210 is sufficient to ensure that the raft layer 200 including the first and second power fill structures 110 and 120 serves as a buoyancy base. It will be determined by engineering calculations taking into account the weight of the upper structure, the bearing capacity of the excavated soil, and gravity.

After the raft layer 200 is formed in the soft ground construction zone, it is possible to suppress settlement by laying the geotextile on the top as in the prior art, as well as increase the friction force by installing the protruding geotextile. .

According to the composite method for treating soft ground according to an embodiment of the present invention described above, improvement of soft ground properties by consolidation of the first and second power fill structures 110 and 120, the first power fill structure 110 A complex solution required for soft ground treatment, such as the role of an underground wall or a water barrier of the first and second power fill structures 110 and 120 and the raft layer 200, and the role of a buoyancy foundation by the raft layer 200 It will be seen that the present invention provides.

Although this complex solution can dramatically reduce the construction depth and number of foundation piles compared to the existing pile foundation method, it is possible to reduce the maximum settlement amount and the differential settlement amount by drastically reducing the stress transmitted to the ground by 1/100, which is As shown in FIG. 9, it can be confirmed by the Burmister stress reduction principle.

In the above, detailed contents for carrying out the present invention have been described together with the accompanying drawings to help the understanding of the technical idea of the present invention, but this is merely illustrative of the preferred embodiment of the present invention and is not limited thereto. , it will be apparent to those of ordinary skill in the art that various modifications or substitutions are possible without departing from the scope of the technical spirit of the present invention.

10 - Soft ground construction area 11 - Power fill injection hole
20 - boundary of soft ground construction area
100 - Powerfill structure
101 - first sub power fill structure 102 - second sub power fill structure
103 - third sub power fill structure
110 - first power fill structure 120 - second power fill structure
200 - raft floor 210 - load distribution section
300 - Powerfill infusion tube
301 - First sub-power-fill injection tube 301 - Second sub-power-fill injection tube
303 - Third sub power fill injection tube
310 - Instant Expansion Composition
S1 - first interval S2 - second interval
D1 - first depth D2 - second depth

Claims (7)

forming a plurality of first power-fill structures of a first depth at first intervals by injecting an instantaneous expansion composition through a power-fill injection pipe along the boundary of the soft ground construction zone;
forming a plurality of second power-fill structures having a second depth at second intervals by injecting an instantaneous expansion composition through a power-fill injection pipe into a soft ground construction zone;
Forming a raft layer on the upper portions of the first power-fill structure and the second power-fill structure in a soft ground construction area; a composite method for treating soft ground, comprising: a. The method according to claim 1,
The raft layer is composed of solidified soil formed by mixing 52 to 136 kg/m of a solidifying agent and 66 to 140 kg/m of mixed water with respect to 1,700 kg/m of soil,
The soil is fine-grained gravel, poor-grained gravel, silt-mixed gravel, clay-mixed gravel, fine-grained sand, poor-grained sand, silty sand, clay sand, silt and clay mixed sand. complex method for 3. The method according to claim 2,
The solidifying agent comprises 40 to 60% by weight of calcined sludge powder, 18 to 24% by weight of blast furnace slag powder, 10 to 32% by weight of quicklime powder, and 3 to 10% by weight of anhydrous gypsum powder. complex method. The method according to claim 1,
The raft layer is
It is located between the adjacent second power-fill structures, and comprises a load distribution part protruding downwardly from the lower surface of the raft layer in an arcuate shape. The method according to claim 1,
Two or more adjacent first power-fill structures overlap each other to form a power-fill band structure having a predetermined width,
A composite method for treating a soft ground, characterized in that a plurality of the power fill band structures are formed with a first interval. 5. The method according to any one of claims 1 to 4,
The power-fill injection tube is composed of two or more sub-power-fill injection tubes of different lengths,
The first power-fill structure is a composite method for soft ground treatment, characterized in that it consists of two or more sub-power-fill structures formed of the instantaneous expansion composition injected by two or more of the plurality of sub-power-fill injection pipes. 5. The method according to any one of claims 1 to 4,
The power-fill injection tube is composed of two or more sub-power-fill injection tubes of different lengths,
The second power-fill structure is a composite method for soft ground treatment, characterized in that it consists of two or more sub-power-fill structures formed of the instantaneous expansion composition injected by the two or more plurality of sub-power-fill injection pipes.

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