JP3528950B2 - Road construction method - Google Patents

Description

Detailed Description of the Invention

[0001]

The present invention relates also to a is about the construction method for building a road by embankment on soft ground.

[0002]

2. Description of the Related Art The following construction method is adopted when constructing a road by embankment on a soft ground having a thick layer of buried soil or alluvium. First, as shown in FIG. 7 , the cement-based solidifying material is dry-mixed in the shallow layer portion of the soft ground 1 and then solidified to form the shallow layer improved soil layer 2a, thereby improving the rigidity of the shallow layer 2 and the improved layer 2. Or, as shown in FIG. 8 , soft ground 1
Quick lime is dry-mixed in the shallow layer portion of No. 3 and then solidified to form a shallow layer improved soil layer 2b, and F is formed on the shallow layer improved soil layer 2b.
The dry ground of e-lime is solidified and then solidified to form the shallow-layer improved soil layer 2c, thereby forming the improved ground 2 having the increased rigidity of the shallow layer. Next, as shown in FIG. 7 and FIG.
Is used as a roadbed, and an embankment composed of a crusher run layer 3a and a crushed stone layer 3b for grain size adjustment is provided on the roadbed to form a roadbed 3, and then an asphalt concrete layer 4 is provided on the roadbed 3 for paving. In this specification, we combined the two leave road pavement without separating the pavement and roadbed.

[0003]

A static load due to embankment and a dynamic load due to running of an automobile are applied to the roadbed of the road, and these loads are transmitted to the roadbed. When the embankment thickness is as thin as about 1.0 m, the dynamic load is comparable to the static load and has a property of repeatedly acting for a long period of time. Therefore, if the degree of ground improvement is not sufficient, even if it can sufficiently withstand the consolidation settlement due to static load, it will not be able to withstand several times that dynamic load, and the road will continue to undergo consolidation settlement due to the dynamic load. It will be. On the other hand, if the ground is sufficiently improved, it is possible to suppress consolidation settlement due to dynamic load, but the relationship between the degree of ground improvement and the suppression effect of consolidation settlement due to dynamic load is not fully understood. For this reason, excessive attempts were made to suppress consolidation settlement, resulting in excessive ground improvement and unnecessarily prolonging the construction period, resulting in wasted construction costs .

An object of the present invention is to provide a road construction method which can be constructed at a relatively short construction period at low cost and which suppresses consolidation settlement due to dynamic load when a road constructed by embankment on soft ground is used. Ru near to provide.

[0005]

The invention according to claim 1 is
As shown in FIG. 1, has a reached all the plurality of pillars 20 to the support layer of soft soil below the soft ground 11 of the road foundation
Constructed with a length and an improvement rate of 10 to 50%, and laying a reinforcing mesh body 21 directly on these plural columnar bodies 20,
This is a road construction method in which the road pavement 18 is directly constructed on the reinforcing net 21. By laying the reinforcing net 21 directly on the columnar body 20 and constructing the road pavement 18 directly on the reinforcing net 21, the shallow layer improved ground 2a shown in FIGS. 7 and 8 is omitted. Thus, it is possible to suppress consolidation settlement due to the dynamic load on the road. Further, since the columnar body 20 has a length that does not reach the supporting layer below the soft ground 11, the construction period is shortened and the construction cost is reduced.

[0006] The invention according to claim 2, as shown in FIG. 2, and 10 all the soft ground support layer length do not want to reach below the plurality of pillars 20 in soft ground 11 of the road foundation
These columnar bodies 20 are constructed with an improvement rate of up to 50%.
A method for constructing a road, in which a shallow improved soil layer 13 is directly laid by mixing and solidifying earth and sand and a solidifying material, and a road pavement 18 is directly constructed on the shallow improved soil layer 13. The thickness of the crusher run layer 18a that constitutes the road pavement 18 by laying the shallow improved soil layer 13 by adding one or both of the additive material and the additive agent to the earth and sand and the solidifying material and mixing and solidifying the mixture. Is 5 to 15 cm, which is a road construction method. A shallow improved soil layer 13 is laid directly on the columnar body 20 by further adding either one or both of the additive and the additive to the solidifying material and the solidifying material to solidify, and the direct road is directly laid on this. By constructing the pavement 18, it is possible to reduce the thickness of the crusher run layer 3a shown in FIGS. 7 and 8 and suppress consolidation settlement due to a dynamic load on the road. Further, since the columnar body 20 has a length that does not reach the supporting layer below the soft ground 11, the construction period is shortened and the construction cost is reduced.

The invention according to claim 3 is the invention according to claim 2 , wherein either one or both of the additive and the additive are further added to the earth and sand and the solidifying material, and the mixture is wet-mixed to be solidified. This is a road construction method for laying the improved soil layer 13. By wet mixing, dust generation by powder at the construction site is suppressed, and the environment near the site is not contaminated with powder. In addition, the wet mixing method does not require compaction and can reduce variations in quality.

[0008] The invention according to claim 4 is the invention according to claim 2 or 3, the additional material is made of foam beads or chaff, the additive is a construction method of a road consisting of bubble generator. By adding a low-density material as an additive or an additive, the shallow layer improved soil layer 13 can be made lighter in weight, and the static load due to the shallow layer improved soil layer can be reduced. Further, since the low density body absorbs the vibration due to the dynamic load, the amount of dynamic consolidation settlement can be reduced.

The invention according to claim 5 is the invention according to claim 2 or 3 , which is a road construction method in which the additive material is a clinker formed by incineration of industrial waste. According to this construction method, it is possible to effectively utilize the clinker which is formed by the incineration of industrial waste and is in need of disposal.

The invention according to claim 6 is the invention according to claim 2 or 3 , which is a road construction method in which the additive material is an inorganic fiber or a synthetic fiber. By adding the above fibers as an additive, the shallow-layer improved soil layer 13 is reinforced, cracking of the improved ground due to traffic load is prevented, and durability of the improved ground is improved. Further, even if the layer thickness is made thinner than the shallow improved soil layer containing no fibers, the same durability as that of the shallow improved soil layer containing no fibers can be obtained.

The invention according to claim 7 is the invention according to claim 1 or 2 , which is a road construction method in which the columnar body 20 is a prefabricated pile or a ground improvement columnar body. By using ready-made piles for the pillars, it is possible to construct at a lower construction period and at a lower cost, and by using the ground improvement pillars, it is possible to more reliably prevent consolidation settlement of roads.

As shown in FIG. 3 , the invention according to claim 8 is the invention according to claim 1 or 2 , wherein the columnar body 20 is a ground improvement columnar body, and a body portion 20a of the columnar body 20 is provided.
It is a construction method of a road having a node portion 20b at the bottom. By providing the node portion 20b on the trunk of the ground improvement columnar body, the settlement resistance of the ground improvement columnar body is increased, and the consolidation settlement of the road can be prevented more reliably.

The invention according to claim 9 is the invention according to claim 1, 2 or 8 as shown in FIG.
0 is a ground improvement columnar body, and is a road construction method in which the tip end of the columnar body 20 has an enlarged portion 20c having a larger diameter than the body portion 20a. By providing the enlarged portion 20c having a larger diameter than the trunk portion at the tip of the soil improvement columnar body, the settlement resistance of the soil improvement columnar body is increased, and the consolidation settlement of the road can be prevented more reliably.

The invention according to claim 10 includes claims 1, 2 and
8 is an invention according to 8 or 9 , wherein the columnar body 20 is a ground improvement columnar body, and the columnar body 20 is a road construction method including an inorganic fiber or a synthetic fiber. By including the fibers in the columnar body, even if a crack is generated in the columnar body due to the lateral flow of the soft ground, the bending resistance of the columnar body is exerted, and the lateral flow thereafter can be suppressed.

[0015] The invention according to claim 11, claim 1,
The invention according to any one of 8 to 10 , wherein the columnar body 20 is a ground improvement columnar body, and is a road construction method in which the columnar body 20 is constructed by a mechanical stirring method or a high-pressure injection stirring method. By constructing the ground improvement columnar body by the mechanical agitation method, it is possible to inexpensively build the outer diameter of the improvement body regardless of the soil quality. Further, by constructing the ground improvement columnar body by the high-pressure injection stirring method, the construction machine can be made smaller and lighter, and the construction machine can be constructed even in a narrow place or under an existing step plate.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is one in which a columnar body which does not reach a supporting layer below the soft ground is constructed on a soft ground, and a reinforcing net or a shallow-improved soil layer is laid on the columnar body. is there. When this combination is adopted, the value L obtained by adding the thickness of the columnar body and the thickness of the road pavement to the thickness of the shallow improved soil layer is used to suppress the consolidation settlement due to the traffic load, that is, the dynamic load. It is a big condition. By setting the improvement rate of the columnar body in the range of 10 to 50% and setting this value L to 4 m or more, consolidation settlement due to a dynamic load can be substantially eliminated. Here, the improvement rate of the columnar body means the percentage of the cross-sectional area of the columnar body to the unit area of the improved ground when the columnar body is viewed from above as shown in FIGS. 5 and 6 . Columnar improvement rate is 10%
If it is less than 50, consolidation settlement cannot be sufficiently suppressed, and
When it exceeds%, there is a problem that the construction period and the construction cost are rather increased. Preferably, this improvement rate is 15 to 30%.

The above value L is required to be 4 m or more, but even if it is increased, the effect of suppressing dynamic consolidation settlement is not so great. However, as the value L increases, the effect of suppressing static consolidation settlement increases accordingly. In the present invention, in order to avoid excessive ground improvement, it does not reach to the supporting layer below the lower end soft ground 11 of the column-like body (not shown). Figure 1 and Figure
2 does not show a supporting layer, the columnar body 20 does not reach the supporting layer in the same manner. The maximum value of this value L is appropriately determined in consideration of the layer thickness of the soft ground and its softness, the load condition, the economical efficiency and the like. As shown in FIG. 1, when the road pavement 18 is directly provided on the reinforcing net 21 without providing the shallow improved soil layer, it is necessary to increase the improvement rate of the columnar body 20.

The reinforcing mesh body 21 of the present invention shown in FIG . 1 is a mesh body formed of a material such as inorganic fiber, synthetic fiber, synthetic resin or steel. The mesh-like body made of inorganic fibers or synthetic fibers is a string-like body made of the fibers and meshed. Examples of the inorganic fiber include glass fiber, and examples of the synthetic fiber include polyamide-based nylon fiber, polyolefin-based polyethylene fiber, polypropylene fiber and the like. Examples of the synthetic resin include polyethylene and polypropylene resin. The reticulate body made of steel is formed by making a large number of cuts in parallel with each other in a plate-shaped steel leaving a peripheral edge and then pulling both edges of the plate-shaped steel in a direction orthogonal to the cuts. The mesh size of the mesh is 10 to 200 mm, and depending on the required degree of reinforcement,
Use one reinforcing net or a plurality of overlapping nets.

As shown in FIG . 2, the shallow improved soil layer 13 of the present invention comprises earth and sand, a cement in the form of powder or slurry, a cement-based solidifying material, a solidifying material such as quick lime, and either an additive or an additive. Alternatively, it is laid by uniformly mixing both and solidifying. Depending on the water content of the target ground, it may be mixed and compacted to form a shallow improved soil layer, or it may be formed without compaction. When the water content of the target ground is low,
If a solidifying material in the form of a slurry is used and then either one or both of the additive and the additive are further added to the solidifying material and earth and sand and wet-mixed, dust generation by powder at the construction site is suppressed, and No more polluting the environment with powder.

Examples of the additive of the present invention include foamed beads, low-density materials such as rice husks, clinker formed by incineration of industrial waste, inorganic fibers or synthetic fibers. Further, the additive of the present invention includes a bubble generator. The above-mentioned additives or additives may be added singly or as a mixture of two or more kinds. You may mix an additive and an additive. Foamed beads are 2 per 100% by volume of the material forming the shallow soil layer.
Add 0-50% by volume. If it is less than 20% by volume, the purpose of addition cannot be achieved, and if it exceeds 50% by volume, the strength of the shallow-layer improved soil layer when solidified decreases. By adding the low density body, the shallow layer improved soil layer can be made lighter in weight, the static consolidation settlement amount can be reduced, and the elastic coefficient of the shallow layer improved soil layer can be reduced to absorb the dynamic load due to traffic load. . Along with this, even if the length of the columnar body is shortened, consolidation settlement can be prevented.

Examples of the low density air bubble generator include polyoxyethylene alkyl ether compounds and higher alcohol sulfate ester compounds. This bubble generator is a liquid before mixing, but is a substance that entrains bubbles in the layer when forming the shallow improved soil layer. When the rice husk is made into a low-density body, the rice husk contains a large amount of SiO ₂ so that it has a high corrosion resistance, and because of its shape, it has a resistance to traffic load in order to increase the shear strength of the shallow improved soil layer for a long time. large. The diameter formed by incineration of industrial waste is 5
When a clinker having a diameter of mm or less is used as the additive, the clinker that is in need of disposal can be effectively used.

When an inorganic fiber or a synthetic fiber is used as the additive, the inorganic fiber such as a steel fiber having a length of about 2 to 4 cm, or the polyamide type nylon fiber or the polyolefin type polyethylene fiber having a length of about 4 to 7 cm is preferable. A synthetic fiber made of polypropylene fiber is used. When the length is less than the above lower limit, the reinforcing effect is poor, and when the length exceeds the above upper limit, it becomes difficult to handle when mixing with other materials. By adding the above fibers as an additive, the shallow improved soil layer is reinforced and cracks of the improved ground due to traffic loads are prevented,
The durability of the improved ground is improved. Further, even if the layer thickness is made thinner than the shallow improved soil layer containing no fibers, the same durability as that of the shallow improved soil layer containing no fibers can be obtained. In order to achieve the above object, rice husks, inorganic fibers or synthetic fibers are 0.1 to 5.0% by volume, preferably 0.2 to 2 with respect to 100% by volume of the material for forming the shallow layer improved soil layer. 0.0% by volume, and the clinker is added at 30% by volume or less. The bubble generator is 0.01 with respect to 100% by weight of the material forming the shallow soil layer.
.About.1.0 wt%, preferably 0.1 to 0.5 wt%.

The columnar construction method includes a method of driving ready-made piles such as wooden piles, ready-made concrete piles, and steel piles into the deep ground, and a method of constructing ground-improved pillars. By using ready-made piles for the pillars, it is possible to construct at a lower construction period and at a lower cost, and by using the ground improvement pillars, it is possible to more reliably prevent consolidation settlement of roads. There are mechanical agitation method and high-pressure jet agitation method as construction methods for constructing this soil improvement columnar body, but if the soil improvement columnar body is constructed by the mechanical agitation method, it will be cheaper and the outer diameter of the improvement body will be constant regardless of the soil quality. can do. Further, by constructing by a high-pressure jet agitation method, the construction machine can be made smaller and lighter, and the construction machine can be constructed even in a narrow place or under an existing step plate. When constructing this soil improvement columnar body, as shown in FIG. 3 , the node portion 20b is provided on the body portion 20a of the soil improvement columnar body 20.
Can also be formed. As a result, the frictional force on the peripheral surface of the soil improvement columnar body increases, the settlement resistance increases, and the consolidation settlement of the road can be prevented more reliably. There is also an advantage that lateral flow of soft ground is less likely to occur. Further, when constructing the soil improvement columnar body, as shown in FIG. 4 , an enlarged portion 20c having a diameter larger than that of the trunk portion 20a is provided at the tip of the soil improvement columnar body 20.
Can also be formed. As a result, the settlement resistance of the ground improvement columnar body is further increased, and the consolidation settlement of the road can be prevented more reliably.

Further, the ground improvement columnar body 20 may contain inorganic fibers or synthetic fibers. In this case, preferably, the inorganic fibers are steel fibers having a length of about 2 to 4 cm,
As the synthetic fiber, polyamide-based nylon fiber, polyolefin-based polyethylene fiber or polypropylene fiber having a length of about 4 to 7 cm is used. When the length is less than the above lower limit, the reinforcing effect is poor, and when the length exceeds the above upper limit, it becomes difficult to handle when mixing with other materials. This fiber is contained in an amount of about 0.2 to 2.0% by volume based on all materials forming the ground improvement columnar body. By including the fibers in the columnar body, even if a crack is generated in the columnar body due to the lateral flow of the soft ground, the bending resistance of the columnar body is exerted, and the lateral flow thereafter can be suppressed.

By constructing the columnar body, lateral flow of the ground due to dynamic load can be prevented. A method of constructing the columnar body when viewed from above will be described based on FIGS. 5 and 6 . Considering the efficiency and economy of construction, the planar arrangement of the pillars should be a lattice arrangement as shown in Fig. 5 or a non-contact staggered arrangement as shown in Fig. 6 so that the improvement rate is as low as possible. It is preferable to suppress it. Improvement rate of 10
When the lattice-like arrangement shown in FIG. 5 is made in the range of 50%, the lattice spacing d ₁ (however, the lattice spacing d ₁ ≧ the lattice spacing d ₂ )
Is less than twice the height from the upper end of the pillar to the road pavement surface, the improvement rate is set in the range of 10 to 50%.
Also in the case of the non-contact staggered arrangement shown in FIG. 6 , when the road direction is D, the columnar body spacing d ₃ (wherein the columnar body spacing d ₃ ≧ columnar body spacing d ₄ ) is the upper end of the columnar body. If the height is less than twice the height from the road to the pavement surface, the static load and the dynamic load are surely transmitted to the columnar body, and the lateral flow of the ground can be sufficiently prevented.

As shown in FIGS. 1 and 2 , the road pavement 18 of the present invention comprises a crusher run layer 18a, a particle size adjusting crushed stone layer 18b and an asphalt concrete 18c. 1 and 2 , the crusher run layer 18a
Has a thickness of 5 to 15 cm, and the particle size adjusting crushed stone layer 18b has a thickness of 10
The asphalt concrete 18c is laid to a thickness of -30 cm, and the asphalt concrete 18c is laid to a thickness of 10-40 cm.

[0027]

Embodiments of the present invention will now be described with reference to the drawings together with comparative examples. <Example 1> As shown in FIG. 1, a ground improvement columnar body 20 was constructed on the target soft ground 11 by a mechanical stirring method with a length that did not reach the support layer below the soft ground 11. At this time, the columnar bodies each had a diameter a of 80 cm and a length L ₁ of 400 cm .
The distances d ₃ and d ₄ shown in 6 are 125 cm, respectively, and the improvement rate is 2
5.7%, non-contact staggered construction. The reinforcing net 21 made of glass fiber is laid on the ground improvement columnar body 20, and the crusher run layer 18a is placed on the grounding net 21 for 30 cm.
Of the asphalt concrete 18c having a thickness of 5 cm. The total length L shown in FIG. 1 was 445 cm.

<Example 2> On the same soft ground as in Example 1, a ground improvement columnar body was constructed by a high-pressure injection stirring method, and a reinforcing mesh body made of steel was laid. The ground was improved in the same manner as in Example 1 except for the above.

<Embodiment 3> On the same soft ground as that of Embodiment 1, as shown in FIG.
Ground improvement columnar body with nodes so that the diameter b of b is 100 cm, the thickness c is 50 cm, the distance d between the nodes is 80 cm, and the length L _{1 of the} columnar body is 400 cm. Twenty built. The ground was improved in the same manner as in Example 1 except for the above. The total length L was 445 cm.

<Embodiment 4> On the same soft ground as in Embodiment 1, as shown in FIG.
A ground-improved columnar body 20 with an enlarged portion was constructed so that the diameter e of 0c was 100 cm, the thickness f was 50 cm, and the length L _{1 of the} columnar body was 400 cm. The ground was improved in the same manner as in Example 1 except for the above. The total length L was 445 cm.

<Example 5> When a ground improvement columnar body is constructed on the same soft ground as in Example 1 by a mechanical stirring method, the material for constructing the columnar body is made of steel having an average length of 6 cm and a thickness of 0.8 mm. The fiber contains 0.2% by weight of the whole material, and the length L ₁ of the columnar body is 400 cm.
I tried to become. The ground was improved in the same manner as in Example 1 except for the above. The total length L was 445 cm.

<Example 6> When a ground improving columnar body is constructed on the same soft ground as in Example 1 by a mechanical stirring method, a vinylon fiber having an average length of 3 cm and a thickness of 350 denier is used as a material for constructing the columnar body. 1.0% by volume of the entire material, the length L ₁ of the columnar body is 400
I made it cm. The ground was improved in the same manner as in Example 1 except for the above. The total length L was 445 cm.

<Embodiment 7> As shown in FIG. 2, a soil improvement columnar body 20 is constructed on the same soft soil 11 as in Embodiment 1 by a mechanical stirring method with a length that does not reach the supporting layer below the soft soil 11. did. At this time, each columnar body has a diameter a of 80 cm and a length L ₂ of 400 cm.
And the intervals d ₃ and d ₄ shown in FIG.
m, improvement rate 25.7%, non-contact staggered construction. On the ground improvement columnar body 20, slurry-like cement-based solidifying material is added to excavated soil and separately prepared earth and sand, and foamed beads of low density are added as an additive material to the whole material 30
Add 3% by volume and wet mix to form a shallow improved soil layer 13 with L ₃ =
It was laid in a thickness of 30 cm. A crusher run layer 18a was laid on this to a thickness of 30 cm, a particle size adjusting crushed stone layer 18b was further laid on this to a thickness of 10 cm, and an asphalt concrete 18c having a thickness of 5 cm was paved on it. The total length L shown in FIG. 2 was 475 cm.

<Embodiment 8> The length L ₂ of the ground improvement columnar body was set to 400 cm, and rice husk as an additive was added in an amount of 20% by volume of the whole material and wet mixed to form a shallow improved soil layer having a thickness L ₃ of 30 cm. It was laid on the same soft ground as in Example 1. The ground was improved in the same manner as in Example 7 except for the above. The total length L was 475 cm.

<Example 9> The length L ₂ of the ground improvement columnar body was set to 400 cm, and a liquid higher alcohol sulfate ester compound (trade name: Fine Foam # 606, N.
(Manufactured by M.B.) was added in an amount of 0.3% by weight based on the total amount of the material, and the mixture was wet mixed to lay a shallow improved soil layer having a thickness L ₃ of 30 cm on the same soft ground as in Example 1. The ground was improved in the same manner as in Example 7 except for the above. The total length L was 475 cm.

<Example 10> The length L ₂ of the ground improvement columnar body was set to 400 cm, and the average particle size formed by incineration of industrial waste as an additive was 20.
A clinker of mm was added in an amount of 20% by volume of the whole material and wet-mixed, and a shallow improved soil layer having a thickness L ₃ of 30 cm was laid on the same soft ground as in Example 1. The ground was improved in the same manner as in Example 7 except for the above. The total length L was 475 cm.

<Example 11> The length L ₂ of the ground improvement columnar body was set to 400 cm, and a steel fiber having an average length of 3 cm and a nominal thickness of 0.8 mm was added as an additive material by 1.0% by volume of the whole material, and then wet. Mixed thickness L ₃
A shallow improved soil layer of 30 cm was laid on the same soft ground as in Example 1. The ground was improved in the same manner as in Example 7 except for the above. The total length L was 475 cm.

<Example 12> The length L ₂ of the ground improvement columnar body was set to 400 cm, and vinylon fiber having an average length of 3 cm and a thickness of 350 denier was added as an additive material in an amount of 1.0% by volume of the entire material and wet mixed. Thickness L ₃
A shallow improved soil layer of 30 cm was laid on the same soft ground as in Example 1. The ground was improved in the same manner as in Example 7 except for the above. The total length L was 475 cm .

<Comparative Example 1> As shown in FIG. 7 , the same target soft ground 1 as in Example 1 was excavated, a cement-based solidifying material was added to the excavated soil and separately prepared soil, and the mixture was dry-mixed. The compacted improved soil layer 2a was laid to a thickness of 60 cm by compaction. A crusher run layer 3a having a thickness of 30 cm is provided thereon, and a crushed stone layer 3b for particle size adjustment is further laid thereon to have a thickness of 10 cm, and the upper layer is paved with asphalt concrete 4 having a thickness of 5 cm. . The total length L shown in FIG. 7 is 10
It was 5 cm.

<Comparative Example 2> As shown in FIG. 8 , the same target soft ground 1 as in Example 1 was excavated, and quick lime was added as a solidifying material to the excavated soil and separately prepared soil, and after dry mixing. The compacted improved soil layer 2b was laid to a thickness of 150 cm by compaction.
Fe lime was dry-mixed on the shallow improved soil layer 2b and then solidified to form a shallow improved soil layer 2c having a thickness of 30 cm. Crusher run layer 3 on this improved shallow soil layer 2c
After a is provided with a thickness of 30 cm, a crushed stone layer 3b for grain size adjustment is further laid on this with a thickness of 10 cm, and 5 c
It was paved with m-thick asphalt concrete 4.
The total length L shown in FIG. 8 was 225 cm.

COMPARATIVE EXAMPLE 3 Except that the ground improving columnar body 20 shown in FIG. 2 is elongated and the lower end of the columnar body is buried in the lower support layer (not shown) of the soft ground. The ground was improved in the same manner as in Example 7 .

<Comparative Test and Results> Regarding the subsidence amount and the occurrence status of steps of roads constructed by the various construction methods of Examples 1 to 12 and Comparative Examples 1 to 3 , it is started after construction. The measurement was performed for a period of time until 720 days after the start of use. Further, with respect to the construction cost required for road construction, the estimated values of other examples and comparative examples when Example 1 was set to 100 were examined.
The results are shown in Table 1.

[0043]

[Table 1]

(A) Regarding the amount of subsidence and occurrence of steps: As is clear from Table 1, both roads constructed by the construction methods of Examples 1 to 12 and roads constructed by the construction methods of Comparative Examples 1 to 3 The settling amount due to static load until the start of use is small, and the construction methods of Examples 1 to 12 and Comparative Example 1
No significant difference was observed between the construction methods of No. 3 and No. 3. Again 1
It could not be said that there was a significant difference between the two examples.
But since the road was used, due to dynamic loading,
The road subsidence by the construction methods of Comparative Examples 1 and 2 was large, whereas the road subsidence by the construction methods of Examples 1 to 12 and Comparative Example 3 were all small. Among the roads produced by the construction methods of Examples 1 to 12 , particularly, Example 3 had the smallest subsidence amount . (b) Construction cost: When the construction cost of the construction method of Example 1 is 100, the estimated construction cost of each construction method of other Examples 2 to 12 is a large ratio of the settlement amount.
Although more expensive than the estimated construction cost of each construction method of Comparative Examples 1 and 2 , about 20% to about 20% of the construction cost of the construction method of Comparative Example 3 in which the lower end of the columnar body is embedded in the support layer. It was as low as 40%.

[0045]

As described above, according to the present invention, a road can be constructed at a low cost in a relatively short construction period without excessive ground improvement that unnecessarily prolongs the construction period. road constructed by embankment when used, Ru can be suppressed consolidation settlement by dynamic load. Twist
Physically, according to the invention of claim 1,
Lay the reinforcing net directly and place it directly on top of this reinforcing net.
Shown in Figures 7 and 8 by building a roadside pavement
The shallow ground improvement ground 2 is omitted and the pressure due to the dynamic load on the road is reduced.
Dense settlement can be suppressed. The columnar body is soft ground
Since the length does not reach the supporting layer below the
This will lead to reductions in cost and construction costs. The invention according to claim 2
According to the above, on the columnar body, add or
Add either or both of the agents and mix to solidify
By laying a shallow improved soil layer directly on the
By building the road pavement shown in Figures 7 and 8
Decrease the thickness of the crusher run layer 3a,
It is possible to suppress consolidation settlement due to static load. Pillar
The shape is a length that does not reach the supporting layer below the soft ground
Therefore, the construction period is shortened and the construction cost is reduced.

[Brief description of drawings]

FIG. 1 is a cross-sectional view seen from a direction orthogonal to a road direction constructed by a construction method according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view seen from a direction orthogonal to a road direction constructed by a construction method according to a seventh embodiment of the present invention.

FIG. 3 is a front view of a ground improvement columnar body having a joint portion in a body portion of the present invention.

FIG. 4 is a front view of a ground improvement columnar body having an enlarged portion at the tip of the present invention.

FIG. 5 is a plan view of a ground improvement columnar body arranged in a grid pattern according to the present invention.

FIG. 6 is a plan view of a ground improvement columnar body arranged in the non-contact staggered pattern of the present invention.

FIG. 7 is a cross-sectional view seen from a direction orthogonal to the road direction constructed by the method of Comparative Example 1.

FIG. 8 is a cross-sectional view seen from a direction orthogonal to the road direction constructed by the construction method of Comparative Example 2.

[Explanation of symbols]

11 soft ground plate 13 shallow improved soil layer 18 paving 18a Kurassharan layer 18b crushed stone for mechanical stabilization layer 18c asphalt concrete 20 columnar body 20a barrel 20b knuckles 20c enlarged portion 21 reinforcing mesh body

   ─────────────────────────────────────────────────── ─── Continued front page    (73) Patent holder 000133881               Tenox Co., Ltd.               6-13-7 Akasaka, Minato-ku, Tokyo (73) Patent holder 000006264               Mitsubishi Materials Corporation               1-5-1 Otemachi, Chiyoda-ku, Tokyo (72) Inventor Tetsuhiko Miura               12-4 Tatemachi, Saka City, Saga Prefecture (72) Inventor Kazuyuki Fujikawa               2-34-5 Minamiikebukuro, Toshima-ku, Tokyo               Inside the ceremony company Diamond Consultant (72) Inventor Takeaki Hama               2-4 Sotokanda, Chiyoda-ku, Tokyo               Within Tokyo Tsubasa Kogyo Co., Ltd. (72) Inventor Hideki Tanaka               4-1-1 Tenjin, Chuo-ku, Fukuoka City, Fukuoka Prefecture                 Tenox Kyushu Co., Ltd. (72) Inventor Shigeru Yoshida               6-13-7 Akasaka, Minato-ku, Tokyo Stock market               Inside the company Tenox (72) Inventor Isao Kobayashi               1-5-1 Otemachi, Chiyoda-ku, Tokyo               Within Mitsubishi Materials Corporation                (56) References JP-A-4-73310 (JP, A)                 JP-A-2-108722 (JP, A)                 JP-A-6-212619 (JP, A)                 JP 10-280433 (JP, A)

Claims (11)

(57) [Claims] 1. A and 10 all the soft ground (11) of the support layer to the length brewing reach <br/> Shinano lower plurality of columnar bodies in soft ground road foundation (11) (20) Constructed with an improvement rate of -50%, laying a reinforcing netting (21) directly on the plurality of columnar bodies (20), and directly road paving (18) on the reinforcing netting (21). ) Is a road construction method. 2. A and 10 all the soft ground (11) of the support layer to the length brewing reach <br/> Shinano lower plurality of columnar bodies in soft ground road foundation (11) (20) ˜50% improvement rate, and the shallow layer improved soil layer (13) is laid directly on the plurality of columnar bodies (20) by mixing soil and solidifying material to solidify, A method for constructing a road for directly constructing a road pavement (18) on an improved soil layer (13), in which one or both of an additive material and an additive agent are added to the soil and solidifying material and mixed. The improved soil layer (13) is laid by solidification, and the crusher run layer (18a) that constitutes the road pavement (18).
The construction method of the road is characterized in that the thickness is 5 to 15 cm. 3. The road according to claim 2, wherein the shallow-improved soil layer (13) is laid by further adding one or both of the additive and the additive to the soil and the solidifying material and wet-mixing to solidify. Construction method. 4. The additive material comprises foam beads or rice husks,
Construction method of road according to claim 2 or 3, wherein the additive consists bubble generator. 5. The road construction method according to claim 2, wherein the additive material is a clinker formed by incineration of industrial waste. 6. The road construction method according to claim 2, wherein the additive material is an inorganic fiber or a synthetic fiber. 7. The road construction method according to claim 1, wherein the columnar body (20) is a prefabricated pile or a ground improvement columnar body. 8. The columnar body (20) is a ground improvement columnar body,
The road construction method according to claim 1 or 2, wherein the body portion (20a) of the columnar body (20) has a node portion (20b). 9. The columnar body (20) is a ground improvement columnar body,
The tip of the columnar body (20) has an enlarged portion (20) having a diameter larger than that of the body portion (20a).
The road construction method according to claim 1, 2 or 8 having c). 10. The road construction method according to claim 1, wherein the columnar body (20) is a ground improvement columnar body, and the columnar body (20) contains an inorganic fiber or a synthetic fiber. 11. The columnar body (20) is a ground improvement columnar body, and the columnar body (20) is constructed by a mechanical stirring method or a high-pressure jet stirring method. Road construction method described in.