KR100857922B1 - Construction method of sand mat for road fill that can save sand through unnecessary cross section reduction - Google Patents

Abstract

The present invention provides a function to smoothly enter the drain equipment during the drain operation to promote the consolidation of the soft ground while providing a function to prevent settlement of the fill load during construction of the road through the fill on the soft clay ground In order to reduce the unnecessary cross-section of the sand mat, which is to be installed on the soft clay ground for the first time during the filling process, it is possible to drastically reduce the construction cost by reducing the use of expensive sand. The present invention relates to a method of constructing sand mats for road fillets, which can achieve sand savings through unnecessary cross-sectional reduction that prevents obstacles in drainage capacity by promoting effective bearing capacity by varying the particle size and shape of sand mats located under the slopes. .

In particular, in the construction method of the sand mat installed between the soft clay ground and the fill layer for the purpose of providing a settlement prevention function of the road made by filling a certain height on the soft clay ground,

The central sand mat located under the central part of the fill is formed of small particles of sand (0.25 to 0.5 mm), and is laid at a predetermined thickness to form a horizontal state.

The edge sand mat located at the bottom of the fill slope is formed of sand grains (1 mm to 2 mm) of coarse particles, and the upper surface is lowered toward the edge.

Description

A sand mat execution method according to the cause that can make sand reduction through unnecessary section reduction for impeachment}

Figure 1 is a cross-sectional view showing a sand mat construction method for filling the road through which the inventors can achieve sand saving through unnecessary cross-sectional reduction,

Figure 2 is a cross-sectional view showing a specific construction example of the sand mat construction method for road fill that can achieve the sand savings by reducing the unnecessary cross-section of the inventors,

Figure 3a, Figure 3b is a schematic cross-sectional view showing the settlement state of the road fill constructed by using the sand mat construction method for road fill that can achieve the sand savings through the unnecessary cross-sectional reduction of the present invention,

Figure 4 is a cross-sectional view showing the numerical value for calculating the sand saving cost of the road fill constructed by using the sand mat construction method for road fill that can achieve the sand savings through the unnecessary cross-sectional reduction of the inventors,

Figure 5a is a cross-sectional view showing a sand mat construction method for a conventional road fill;

Figure 5b is a schematic cross-sectional view showing a settlement state of the road fill constructed by using a sand mat construction method for the conventional road fill;

Figure 6a is a cross-sectional view showing another conventional sand mat construction method for land fill,

Figure 6b is a schematic cross-sectional view showing a settlement state of the road fill constructed by using another conventional sand mat filling method for the road fill.

<Description of the symbols for the main parts of the drawings>

c: Filling center s: Filling slope (s)

1: soft ground 2: sand mat

4: fill 6: 6: layer

8: road 10: correction settlement

100: sand mat 100a: center sand mat part

100b: edge sand mat portion 102: sand of small particles

104: coarse grains of sand

The present invention relates to a sand mat construction method for road fill that can achieve sand saving through unnecessary cross-sectional reduction, and more particularly, to provide a function of preventing settlement of roads that are constructed by filling in soft clay ground. To reduce the costly sand consumption by reducing the unnecessary cross-section of the sand mat part, which is installed on the soft clay ground for the first time during the filling process, to provide a function to facilitate the entry of the drain equipment during the drain work to promote the consolidation of It is possible to realize a significant reduction in the construction cost due to the construction, and by varying the particle size and shape of the contents of the sand mat located at the center of the fill and the bottom of the slope where the sedimentation amount is different during actual use, it is effective to promote the bearing capacity and the barriers to drainage capacity. To eliminate unnecessary cross section reduction It relates to methods for road construction sand mat sand embankment that can achieve savings.

In general, soft ground is composed of soil composed of fine particles such as clay or silt, organic soil with large gaps, peat soil, loose sand, etc., and high groundwater level. It refers to the ground to generate.

When civil engineering works are carried out on such soft ground, if the ground is used as it is, stability problems may occur.

In such a case, it is called the ground improvement to improve the engineering properties of the ground and increase its stability.

In general, the purpose of the soft ground improvement method is divided into the following four.

(1) Improvement of strength characteristics: The strength of the ground is the resistance to the destruction of the ground. The resistance to ground failure depends on the shear strength of the soil.

(2) Improvement of deformation characteristics: Soil deformation is divided into soil volume change and shape change. In order to improve such characteristics, the compressibility is lowered or the shear strain coefficient is increased.

(3) Improvement of exponentiality: When soil water moves during or after construction, various problems occur due to the change of effective stress, which can be prevented by improving the exponential of the ground.

(4) Improvement of dynamic properties: In loose sandy soils, the pore water pressure may increase due to earthquake or ground dynamics, and liquefaction may occur due to effective stress reduction. To prevent liquefaction, the liquefaction resistance must be increased. Since the liquefaction resistance is related to the soil density, particle size distribution, skeletal structure, saturation, and initial effective stress of the soil, in order to increase the resistance to liquefaction, rapid dissipation of excess pore water pressure and supply cutoff of excess pore water pressure at the periphery For example, there are ways to reduce shear deformation during earthquakes.

Determination of the necessity of soft ground improvement works should be made after comprehensive judgment in consideration of the function, basic type, and air of the structure.

The soft ground improvement methods include preloading method, vertical drainage method, sand compaction pile method, etc., which are introduced from abroad and have many construction experiences in Korea. There are various methods, such as vacuum consolidation method, which are used for special purpose and have recently been introduced in Korea.

In selecting the soft ground improvement method, select the method that considers the purpose of countermeasures, the characteristics of the ground, the air, and the influence of the surrounding area. do.

(1) Points to note when selecting a construction method: Soft ground measures are established to make safe and economic road structures.

Soil improvement does not necessarily exist on the basis of one principle, but is often applied in a mixed parallel method based on a plurality of principles.

Therefore, when selecting the soil improvement method, it is necessary to clarify the purpose of the improvement, and in consideration of the conditions such as the characteristics of the ground, load conditions, construction conditions, construction period, and the surrounding natural environment and surroundings, the improvement objectives and smooth construction. In this regard, appropriate construction methods should be established in consideration of economic feasibility.

(2) Characteristics of roads and soft grounds: When constructing roads on soft grounds, the type and size of the roads shall be determined to determine whether the soft grounds have an engineering meaning. This can be done by comparing and evaluating the allowable bearing capacity and allowable settlement for the target road structure from the results of ground surveys, field surveys, and laboratory tests. The characteristics of the soft ground need to be reviewed in the original ground condition first, in order to determine whether the countermeasure method is implemented in combination with the structure condition.

If it is determined that a countermeasure is necessary, it is necessary to select a countermeasure method. Therefore, each countermeasure method according to this should select a countermeasure method suited to the conditions of the ground.

(3) Purpose of soft ground countermeasures: As a result of the design review, it is necessary to clarify what causes problems with the original ground, the purpose of countermeasures, and the degree of countermeasures.

(4) Constraints on air and environment: Air is a factor in the selection of construction methods. For example, in the case of the preloading method, the improvement ratio is also relatively inexpensive compared to other methods, and it is relatively easy in the construction technology, but it takes a long time to obtain a predetermined improvement effect, so it is effective in a thick clay layer that allows a long time of air. In the case of severe air constraints, it is possible to select a sand compaction file having a higher substitution rate than a vertical drainage or a deep mixing process that can be obtained within a few weeks.

In recent construction work, environmental consideration is a big problem.

Therefore, the existing structures should not be affected, but the compaction method or the quicklime pile method, which excludes the original ground, may cause deformation of the existing structures, and the settlement of the remaining structures by consolidation. Consideration should be given to the impact. And the problem of groundwater contamination by chemical injection method should be considered.

Determination of countermeasure methods requires abundant knowledge and experience, and should be selected in consideration of ground conditions, road conditions, construction conditions, etc., and may be handled solely, but in most cases, two or more methods are used in combination. .

(1) Loading method (preloading, vacuum pressure) + vertical drainage method (sand drain, pack drain, paper drain, menard drain, crushed stone drain)

(2) Loading method + pressure soil

(3) Vertical drainage method + sand compaction method (SCP) method

(4) Sand Mat + (1)

(5) Sand Mat + Geotextile + (1)

(6) Sand Mat + Geotextile + (2)

(7) Sand Mat + Geotextile + (3)

(8) Vertical drainage method + mixed treatment method

(9) other

The sand mat laying hole is a sand mat laid on the soft ground to act as an upper drainage layer for smooth drainage of water discharged due to the consolidation of the soft ground and the underground to block the rise of groundwater into the crushed soil. It is laid for the purpose of the drainage layer and the role of the support layer to secure the trafficability of the construction equipment.

For reference, the thickness of the sand mat is determined by considering two conditions, such as equipment running and drainage function. The sand mat thickness for the equipment running is determined by the undrained shear strength of the equipment when the ground is soft clay ground. It is a major factor in determining driving ability.

Therefore, given the undrained shear strength of the target soft ground, it can be used to calculate the allowable bearing capacity of the ground when designing, and from this, it is possible to determine the thickness of the sand mat considering the running ability of the equipment.

In addition, the sand mat thickness calculation for drainage function should be able to play a role as a horizontal drainage of the gap water discharged while the soft ground is consolidated settlement of the soft ground.

Therefore, when the soft layer is thick, when the pile width is wide, when the discharge of water due to consolidation, etc., a sufficient sand mat thickness is required to properly perform the role of the drainage.

In the construction of such sand mats, a sufficient amount of preparation drainage is used to reduce the disturbance of the foundation ground due to the construction, and to prevent the mixing of clay and the like, thus preventing the drainage effect.

In addition, the material of the sand mat needs to select a material that is not refined.

In case of wide range of stacking, both sides should be considered first and construction method should be considered according to the surface condition and weakness of the surface, and neglect pressure to avoid uneven laying thickness.

In the arrangement of underground drainage holes, it is provided in the longitudinal direction or the transverse direction of the body, but in the case of the installation in the longitudinal direction, it is advantageous to shorten the water passage distance.

It is necessary to be careful that the underground drain hole is installed in the sand mat so that fine grains, such as clay, invade the drain hole and thus reduce the drainage effect.

In particular, when there is a large amount of drainage, it is preferable to add underground drain holes or use perforated pipes.

Thus, the vertical drainage method is a kind of soft ground improvement method that promotes drainage by pouring drain material under the sand mat, and a method of promoting consolidation by shortening the drainage distance by artificially installing a plurality of vertical drains in the soft clay soil. Also called vertical drain method.

In addition, the surface horizontal drainage method is a method of draining the consolidation water of the clay layer horizontally by sand mat without applying the vertical drainage method when the thickness of the soft ground is small.

When the clay ground is improved and filled using the vertical drainage method and the horizontal drainage method, the central part of the fill is concave like the shape of the pear so that the settlement of the central part is increased, so that natural drainage is difficult.

In addition, the sand mat that is directly installed on the upper soft clay ground, if the lower ground is soft, because a large amount of depression into the ground ground, the construction machine is frequently conducted because there is a lack of ground pressure to withstand the weight of the drain pouring machine and other construction machinery.

In addition, clay ground is also greatly disturbed. As a result, the drainage effect is reduced due to the construction delay caused by the danger of falling of the construction machine and the permeability coefficient of the ground in the ground disturbance region.

In addition, sand mats are buried under the original clay at the time of filling, and drainage is impossible.

Therefore, in order to promote the drainage area, it is important to install the vertical drainage material and sand mat overlapping each other, and in the case of the vertical drainage material, it is important to select the settled soil having a larger permeability coefficient than the clay ground.

Depending on the construction method, sand drain method, pack drain method, and plastic, which is a vertical drainage method that shortens the drainage distance by installing column-shaped sand piles for the drainage function inside the clay layer, Paper) Drain Method

(plastic drain method), crushed pile method (gravel drain method).

In addition, sand compaction method, which is a compaction pile system that injects material into the casing medium by a press-fit compaction machine, forms compaction piles by drawing and compression, and simultaneously promotes bearing capacity and drainage of sand and crushed stone piles. It is divided into the "gravel compaction method".

In the vertical drainage method, the plastic drain method is a method of promoting consolidation in the ground by inserting a specially processed plastic material instead of sand or a card-board thereof.

Compared with sand drain method, plastic drain method is simpler and faster in construction, less disturbance in clay ground during penetration, and constant drain cross section in depth direction enables reliable construction, good drainage effect, and low construction cost. There is an advantage.

The sand (gravel) drain method and the sand (gravel) compact method are widely used and relatively expensive in recent years due to the development of construction machinery, which brings certain consolidation and compaction effects in land and sea works.

In recent years, excessive maritime harvesting in coastal areas has resulted in imbalances in coastal ecosystems and reduced catches.

Therefore, in order to continuously supply aggregates for construction materials, we are actively developing sand resources in the exclusive boundary waters.

Due to this situation, securing of drainage materials for soft ground treatment is lagging in view of the importance of supplying preferential concrete aggregate, and the soft ground improvement construction is facing a more difficult time.

Therefore, there is a need for a countermeasure technique that can improve drainage function when materials that are somewhat unsuitable to the particle size criteria are used to improve the soft ground economically and efficiently.

For this study, the application of soft aggregates or fiber mat materials was used to examine the applicability of soft ground drainage by indoor testing, or to install horizontal holes in order to maintain the function of horizontal drainage using dredged soil as an alternative to sand mat.

Although the need for drainage measures has been suggested, these previous studies have not yet proposed the normal mechanism, design, and construction techniques considering the overall sand mat drainage and ground subsidence.

The prior art will be described below with reference to the drawings for clarity.

5A is a cross-sectional view illustrating a conventional sand mat construction method for road fill, and FIG. 5B is a schematic cross-sectional view illustrating a settlement state of road fills constructed using a conventional sand mat construction method for road fill.

As shown, after laying the sand mat 2 to a predetermined thickness on the soft ground 1, the drain pouring machine and other construction machines are run and placed on top of the sand mat 2 to artificially cast the vertical drain material. (Not shown), followed by filling the soil 4 at a predetermined height in the form of upper and lower beams on the top of the sand mat 2, and placing the pavement layer 6 on the soil 4 above. The road 8 is constructed.

In the case of the road constructed as described above, as shown in FIG. 5B, partial deformation of the sand mat 2 may occur due to the consolidation settlement phenomenon that occurs due to the load transfer of itself during the filling 4.

That is, the sand mat located at the lower portion of both slopes of the fill (2) with relatively low load transfer of the sand mat (2) located in the lower portion above the center of the fill (4) where load loading of the fill (4) itself is concentrated. (2) As shown in the drawing rather than the site will be concentrated sinking.

Accordingly, the sand mat 2 located at both sides of the sand mat 2 is located upward from the sand mat 2 located at the center, and thus, the sand mat 2 may not function as an initially intended horizontal drainage.

As described above, the portion of the sand mat 2 positioned below the inclined portions of the fill 2 has a lower settlement level due to the less load transfer relative to the sand mat 2 positioned at the center. Therefore, even though the thickness of the sand mat 2 does not need to be as thick as the central portion, since the same thickness is installed, there is a problem of causing an increase in construction cost due to unnecessary use of expensive sand.

In recent years, development of countermeasure technology to solve such a problem phenomenon has emerged one after another.

This will be described in more detail with an example (application number 10-2006-0048424) as follows.

Figure 6a is a cross-sectional view showing another conventional sand filling method for land fill proposed as an alternative for solving the above-described conventional problems, Figure 6b is constructed using another conventional sand filling method for land fill It is a schematic sectional drawing which shows the settlement state of road fill.

As shown in the figure, the corrected settlement soil 10 is first laid in the form of upper and lower subsidence, and then the sand mat 2 is laid on the upper portion of the corrected settlement soil 10 with a predetermined thickness. The drain pouring machine and other construction machines are run and positioned on the top of the sand mat 2 to artificially cast the vertical drain material, followed by the filling 4 by a predetermined height, and the pavement layer 6 on the top of the filling 4. To build a road (8).

As such, the road 8 constructed as described above effectively supports and supports the loading loads generated in the fill 2 process, and greatly reduces the settlement phenomenon occurring during the fill 2 process, and initially intended horizontally. On the other hand, it has the following problems.

If you explain this in detail according to the order,

First, there is a problem that the work delay and construction cost increase due to the increase in the number of airborne and materials due to the use of settlement soils.

Second, as settling correction soil is laid out in the form of upper and lower subsidence, the sand mats that are subsequently laid are also installed in the upper and lower subsidence. It provided obstacles in the running and stable installation of drain pouring machine and other construction machine.

That is, since the drain pouring machine and other construction machines are moved and positioned to the top of the sand mat formed to be inclined to both sides, the vertical drain material is to be poured and the collapse of the sand mat is caused.

Third, there is a problem that the settlement soil loses the function of the sand mat by providing a factor that inhibits the smooth pitch of the ground.

That is, the settlement soil is mixed with the sand mat by the loading load during the filling process, and as a result, a phenomenon that greatly disturbs the foundation ground is caused. This is because it causes a phenomenon.

Fourth, since the sand mat is laid in a protruding form as shown in the figure, there is an uneconomical problem that leads to an increase in construction cost due to the increase in the distance of expensive sand mat laying.

The present invention has been made in view of the conventional problems as described above, and its object is to provide a function to prevent settlement of the ground due to the fill load during construction of the road through the fill on the soft clay ground and consolidation of the soft ground. Construction costs due to the reduction of expensive sand usage by making unnecessary cross-sectional reduction of sand mat, which is installed on soft clay ground for the first time during the filling process, to provide the function to facilitate the entry of drain equipment during draining work The size and shape of the contents of the sand mat part located in the central part of the soil and the lower part of the slope where the settling amount is different when the actual use is settled can be greatly reduced. Reduced Sand Through Section Reduction To provide a fill for road construction methods that you can rule the sand mats.

Specific means of the present invention for achieving the above object,

In the construction method of the sand mat which is installed between the soft clay ground and the fill layer for the purpose of providing settlement prevention function of the road is made by filling a certain height on the soft clay ground,

The central sand mat located under the central part of the fill is formed of small particles of sand (0.25 to 0.5 mm), and is laid at a predetermined thickness to form a horizontal state.

The edge sand mat located at the bottom of the fill slope is formed of sand grains (1 mm to 2 mm) of coarse particles, and the upper surface is lowered toward the edge.

Hereinafter, the configuration of the present invention in detail with reference to the drawings.

1 is a cross-sectional view showing a sand mat construction method for the road fill that can achieve the sand savings through the unnecessary cross-sectional reduction of the present inventors, Figure 2 is a sand mat for road fill that can achieve the sand savings through the unnecessary cross-sectional reduction of the inventors. It is a cross section shown to show the specific construction example of a construction method.

For reference, in describing the present invention, when it is determined that a detailed description of related known functions or configurations may unnecessarily obscure the gist of the present invention, the detailed description thereof is omitted.

In addition, terms to be described below are terms defined in consideration of functions in the present invention, which may vary according to intentions or customs of users and operators.

Therefore, the definition should be made based on the contents throughout the specification.

As shown, the central sand mat part 100a positioned below the center portion of the fill is formed of sand 102 having small contents, and is formed to have a predetermined thickness so as to form a horizontal state. s) Edge sand mat portion (100b) located in the lower portion is formed of a grain of sand grains (104) of coarse particles, it is laid lower to the edge.

Here, the central sand mat portion 100a is formed of sand 102 of small particles having a size of about 0.25 mm to 0.5 mm, and the edge sand mat portion 100b has a size of about 1 mm. It is formed of coarse grains of sand 104 having a size of ˜2 mm.

On the other hand, the coarse grained sand grains 104 are formed, but the edge sand mat portion (100b) is installed so that the upper surface is lowered toward the edge is the center of both sides on the basis of the center (D) of the whole sand mat 100 Both ends of the edge sand mat part 100b and the end of the edge sand mat part 100b are laid at a half thickness (H / 2) of the installation thickness H of the center sand mat part 100a. It is laid.

The sand mat 100 installed in this way is in a state as shown in Figure 3a, 3b by the loading after the final fill.

That is, the central sand mat part 100a positioned below the central part c of the filled area 4 to which stress concentration due to the filled area 4 load is applied is recessed, in which the center has a somewhat large depression. In this case, the edge sand mat portion 100b located below the both slopes of the fill 4 having relatively low stress concentration due to the loading load has a very high degree of depression as shown in the drawing rather than the central sand mat portion 100a. Less appears.

Accordingly, the overall shape of the sand mat 100, which is finally implemented after the fill 4, is sand that has been laid with a uniform thickness so as to maintain a horizontal state with the edge sand mat part 100b that has been inclined downwardly toward the edge. The mat part 100a has a cross-sectional shape close to a horizontal state.

Therefore, considering the sinking shape of the sand mat 100 due to the load (4) loading load when constructing the road (8), it is possible to achieve sand saving through unnecessary cross-sectional reduction, thereby reducing the waste of natural resources and significantly reducing the construction cost. It becomes possible to plan.

For reference, the sand saving cost through the cross-sectional reduction described above is roughly calculated with reference to FIG. 4.

① Total area calculation

② Calculation of reduction area

③ Sand saving cost by area calculation

And, the final shape of the sand mat 100 is finally implemented to form a cross-sectional shape close to the horizontal, the central sand mat portion 100a of the sand mat 100 is sand (0.25 ~ 0.5mm: particles of small contents): (102), and the edge sand mat part 100b is formed of sand grains (1 mm to 2 mm: 104) of coarse particles, so that the edge sand mat 100b can effectively serve as an initial intended horizontal drainage.

That is, the shape of the sand mat 100 is formed to facilitate the horizontal drainage, as well as to facilitate the drainage of water discharged due to the consolidation of the soft ground (1) through the arrangement of sand particles effective for drainage strokes. In addition to acting as the upper drainage layer, it is possible to effectively perform the role of the underground drainage layer to block the rise of groundwater into the crushed soil.

In addition, as described above, the central sand mat part 100a, which is located at the center of the sand mat 100, has a constant thickness to maintain a horizontal state, but has a small content of sand (0.25-0.5 mm: (102) ), The horizontal drainage stroke as described above is effective, while the non-drainage shear strength is used to stabilize the running and installation of the drain pouring machine and other construction machines that cast the vertical drain material to promote the compaction of the soft ground. It is suitable to prevent the occurrence of unnecessary increase in the thickness of the sand mat 100 for the stable running and installation of such equipment, thereby reducing the waste of natural resources due to the sand saving and construction cost. It becomes possible.

For reference, the present invention may be variously modified and may take various forms. However, in the detailed description of the present invention, only specific embodiments thereof are described.

Therefore, it is to be understood that the invention is not to be limited to the specific forms referred to in the description, but rather to include all modifications, equivalents and alternatives falling within the spirit and scope of the invention as defined by the appended claims. It must be understood.

As described above, the present invention provides a function of preventing settlement due to the loading load of the ground during the construction of the road through the fill on the soft clay ground, and also facilitates the entry of the drain equipment during the drain work to promote the compaction of the soft ground. In order to provide a function for planning, the unnecessary cross-sectional reduction of the sand mat, which is installed on the soft clay ground for the first time during the filling process, has the effect of drastically reducing the construction cost by reducing the use of expensive sand.

In addition, by varying the particle size and shape of the contents of the sand mat located in the central part and the lower part of the sediment where sedimentation amounts are different when the yarn is used, it is effective to promote the bearing capacity and to eliminate the obstacles of drainage capacity. It can improve working safety and convenience by providing a space suitable for driving and installation stability of drain pouring machine and other construction machines for pouring drain material, and unnecessary sand for driving and installation stability of such equipment. It is possible to reduce the sand by not having to increase the thickness of the mat, and to reduce the waste of natural resources and to further reduce the construction cost.

Claims (3)

delete delete In the construction method of the sand mat which is installed between the soft clay ground and the fill layer for the purpose of providing settlement prevention function of the road is made by filling a certain height on the soft clay ground, The central sand mat part 100a, which is located below the central part of the fill area, forms the contents as small particles of sand 102, and installs a predetermined thickness to form a horizontal state. Edge sand mat portion (100b) is located at the bottom of the fill slope (s) is to form the contents of the grains of coarse grain of sand (104), the lower the upper surface is laid, The center sand mat part 100a is formed of sand 102 of small particles having a size of about 0.25 mm to 0.5 mm, and the edge sand mat part 100 b is about 1 mm to 2 mm in size. Formed from the grains of coarse grains of sand (104) forming the size of, the edge sand mat portion (100b) from the site to be the center (D / 2) of both sides on the basis of the center (D) of the whole sand mat 100 Cross-section reduction is characterized in that both ends of the installation of the sand sand mat 100b and the end of the sand sand mat 100b are laid so as to be half the thickness H / 2 of the thickness H of the central sand mat 100a. Sand mat construction method for road fill that can achieve sand saving through

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