JP2019132094A - Design method and construction method for honeycomb structural body mattress method - Google Patents

Abstract

To provide a design method and a construction method expecting a restraint effect for the cell structure of a honeycomb structural body in a honeycomb structural body mattress method.SOLUTION: The design method for honeycomb structural body mattress method includes arranging strip materials made of a plurality of long pieces of resin or fiber sheets on a structure foundation in a width direction, partially joining the strip materials to each other at predetermined intervals in a zigzag manner repeatedly, and extending this in a direction perpendicular to the width direction, thereby installing a honeycomb structural body made by filling a honeycomb-like three-dimensional reinforcement forming honeycomb-like cells with a filling material. The design method for honeycomb structural body mattress method is characterized to compare ground reaction force P and allowance bearing capacity qa obtained by dividing ultimate bearing capacity qu of a foundation ground by a safety factor Fs and to make up the shortage of the allowance support capacity qa with respect to the ground reaction force P using the increment of bearing capacity σR/Fs by means of a honeycomb structural body mattress method installed on the structure foundation.SELECTED DRAWING: Figure 6

Description

  In the present invention, strip materials made of a plurality of long pieces of resin or fiber sheets are juxtaposed in the width direction, and are partially joined in a staggered manner at predetermined intervals, and these are joined in a direction perpendicular to the width direction. More specifically, a honeycomb structure in which a honeycomb structure formed by spreading the honeycomb-shaped three-dimensional reinforcing material and filling a filling material is installed under the structure. The present invention relates to a design method and a construction method of a structure mattress construction method.

  Conventionally, when a structure is constructed on soft ground, a method of replacing the base portion of the structure with crushed stone or the like to strengthen the supporting force is a widely used method. Further, in order to reduce the replacement thickness, it is also widely used a reinforcing material such as a geogrid. Patent Document 1 discloses a mattress method in which crushed stone is wrapped in a geogrid on the foundation ground of a gas station. .

  On the other hand, strip materials made of a plurality of long pieces of resin or fiber sheet are juxtaposed in the width direction, and are partially joined in a staggered manner at a predetermined interval, and this is stretched in a direction perpendicular to the width direction. There is known a honeycomb-shaped three-dimensional reinforcing material that forms honeycomb-shaped cells, and this honeycomb-shaped three-dimensional reinforcing material is filled with earth, sand, crushed stone, etc. (hereinafter, honeycomb-shaped three-dimensional reinforcing material is filled with earth, sand, crushed stone, etc. This structure is referred to as a “honeycomb structure”) and has been used for ground reinforcement, road base material, sidewalk foundation materials, temporary roads, and retaining wall materials.

  This honeycomb structure is also employed in the mattress method, and Patent Document 2 proposes a method combining a geogrid and a honeycomb structure.

  However, in these methods, structural calculation is performed in a configuration in which crushed stone is attached to the entire mattress range and this is wrapped with a geogrid, and structural calculation that takes into account the restraining effect due to the cell structure of the honeycomb structure is not performed.

JP-A-8-209670 JP 2010-255247 A

  An object of the present invention is to provide a design method and a construction method that allow for the effect of restraining the cell structure of the honeycomb structure in the honeycomb structure mattress method.

  The present inventor has found a supporting force increase effect due to the cell structure in the honeycomb structure mattress method, and incorporates the supporting force increase effect in the design method of the mattress method, so that even if the replacement thickness is smaller than the conventional mattress method. It has been found that sufficient support for the structure can be obtained.

The invention described in claim 1
A strip material made of a plurality of long pieces of resin or fiber sheets is juxtaposed in the width direction on the foundation of the structure, and partially joined in a staggered manner at predetermined intervals, and this is orthogonal to the width direction. A honeycomb structure mattress construction method in which a honeycomb structure is formed by filling a honeycomb-shaped three-dimensional reinforcing material with a filling material to form a honeycomb-shaped cell by spreading on a honeycomb structure,
Compare the ground reaction force P with the allowable bearing force qa obtained by dividing the ultimate bearing force qu of the foundation ground by the safety factor Fs.
This is a design method for a honeycomb structure mattress method characterized in that a deficiency in the allowable support force qa with respect to the ground reaction force P is compensated by an increase in support force σR / Fs by the honeycomb structure mattress method installed on the structure foundation.

  That is, the design method of the honeycomb structure mattress construction method of the present invention is not sufficient when the ground support force qa is small with respect to the ground reaction force P and the honeycomb structure mattress is installed between the structure and the ground. The gist of the invention is to supplement the allowable supporting force qa with the increase in supporting force σR / Fs by the honeycomb structure mattress.

The invention according to claim 2
The method for designing a honeycomb structure mattress construction method according to claim 1, wherein the step of calculating a supporting force increase σR by the honeycomb structure mattress is the following steps 1) to 4).
1) Calculation of main earth pressure coefficient Ka Ka = tan ² (45 ° −φ / 2)
Where φ is the internal friction angle of the filling material filled in the honeycomb structure 2) Calculation of horizontal stress σm in the cell σm = Ka · σv
However, σv is the vertical stress generated in the cell, that is, the ground reaction force P
3) Calculation method of shear resistance τ of cell τ = σm · tanδ
Where δ is the friction angle of the wall between the cell and the filling material of the cell 4) Method for calculating the increase in bearing capacity σR σR = 2 · τ · (H / D) · [1 + π / (4-π)] ≒ 9 · τ ・ (H / D)
Where τ is the shear resistance of the cell
H is the height of the cells constituting the honeycomb structure
D is the diameter only when the cells constituting the honeycomb structure are regarded as circles.

  That is, the increase in bearing capacity σR by the honeycomb structure mattress in the design method of the honeycomb structure mattress construction method of the present invention is the internal friction angle φ of the filling material filling the honeycomb structure and the wall friction between the cells and the filling material. If the four variables of the angle δ, the height H of the cells constituting the honeycomb structure, and the diameter D only when the cells constituting the honeycomb structure are regarded as a circle are determined, the calculation can be performed.

The invention described in claim 3
The honeycomb structure mattress construction method according to claim 2, wherein a wall friction angle δ between the cells and the filling material of the cells has the same value as an internal friction angle φ of the filling material filled in the honeycomb structure. .

  The internal friction angle φ of the filling material and the wall friction angle δ between the cell and the filling material have the same value.

The invention according to claim 4
The height H of the cells constituting the honeycomb structure calculated by the design method of claims 1 to 3, and the diameter D only when the cells constituting the honeycomb structure are regarded as a circle,
A process of selecting a honeycomb-shaped three-dimensional reinforcing material,
A step of excavating the flooring portion of the structure installation location to a depth where the H can be accommodated;
Extending the honeycomb-shaped three-dimensional reinforcing material, filling the honeycomb-shaped three-dimensional reinforcing material with the filling material, and installing the honeycomb structure;
Including the step of installing the honeycomb structure mattress by setting one or more layers of the honeycomb structure until the height H is reached,
This is a construction method of the honeycomb structure mattress construction method.

  INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a honeycomb structure mattress construction method in which the range of the mattress installed under the structure is set to a necessary minimum depth and construction range.

It is a perspective view before the expansion of a honeycomb-shaped solid reinforcing material. It is a perspective view at the time of extending a honeycomb-like solid reinforcing material. It is sectional drawing which showed the concept of the load to the ground of a structure. It is sectional drawing which showed the concept of the load at the time of replacing a structure foundation with high quality soil. It is sectional drawing at the time of installing a honeycomb structure under a structure (box culvert). It is sectional drawing which showed the concept of the load at the time of using a honeycomb structure for a structure foundation. It is sectional drawing which showed the concept of the transmission of force when a load is applied to a honeycomb structure from the top. It is a top view explaining the concept of the supporting force increase by a honeycomb structure. FIG. 4 is a perspective view (left) of the deemed circle portion 11 and a development view of the circumferential portion of the deemed circle portion 11. FIG. 3 is a perspective view (left) of the deemed valley portion 12 and a developed view of a side surface portion of the deemed valley portion 12. It is a conceptual diagram (especially in the case of Example 2) of the test in Examples 1-3. It is the photograph at the time of installing a honeycomb structure on the ground. It is the photograph at the time of applying a loading load from the upper part to a honeycomb structure. 3 is a graph showing a relationship between a loading pressure P and a settlement amount S.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same components are denoted by the same reference numerals, and description thereof will be omitted as appropriate. Moreover, this embodiment is only one form for implementing this invention, and this invention is not limited by this embodiment, A various change embodiment is in the range which does not deviate from the summary of this invention. Is possible.

Embodiment
The gist of the present invention is a design method for installing a honeycomb structure in a mattress shape on a structure foundation, and that the replacement width and the replacement thickness can be reduced by using the design method. However, no such case has been known so far.

That is, the present invention
A strip material made of a plurality of long pieces of resin or fiber sheets is juxtaposed in the width direction on the foundation of the structure, and partially joined in a staggered manner at predetermined intervals, and this is orthogonal to the width direction. A honeycomb structure mattress construction method in which a honeycomb structure is formed by filling a honeycomb-shaped three-dimensional reinforcing material with a filling material to form a honeycomb-shaped cell by spreading on a honeycomb structure,
Compare the ground reaction force P with the allowable bearing force qa obtained by dividing the ultimate bearing force qu of the foundation ground by the safety factor Fs.
This is a design method for a honeycomb structure mattress method characterized in that a deficiency in the allowable support force qa with respect to the ground reaction force P is compensated by an increase in support force σR / Fs by the honeycomb structure mattress method installed on the structure foundation.

The honeycomb-shaped three-dimensional reinforcing material and honeycomb structure used in the present invention will be described.
FIG. 1 is a perspective view of a honeycomb-shaped three-dimensional reinforcing material (3 cells) used in the present invention before expansion. In the present embodiment, the three-cell honeycomb three-dimensional reinforcing material is exemplified, but the number of cells of the honeycomb three-dimensional reinforcing material is not limited to three cells and may be any number. The same applies to the honeycomb structure and the honeycomb retaining wall made from the honeycomb-shaped three-dimensional reinforcing material. The honeycomb-shaped three-dimensional reinforcing material 1 has a strip material 2 made of a plurality of long pieces of resin or fiber sheets arranged in parallel in the width direction, and is repeatedly staggered at a predetermined interval and partially at a joint portion 4 at a constant interval. It is a combination. The honeycomb-shaped three-dimensional reinforcing material 1 is expanded in the extending direction a to form a honeycomb-shaped cell structure. Resin is preferable as the material used for the honeycomb-shaped three-dimensional reinforcing material, and among the resins, high-density polyethylene is preferable.

  In some cases, the strip material 2 is provided with holes 3 for discharging water accumulated in the cells. The hole may have any size or shape.

  FIG. 2 is a perspective view when the honeycomb-shaped three-dimensional reinforcing material (3 cells) shown in FIG. 1 is stretched. When the honeycomb-shaped three-dimensional reinforcing material 1 is stretched, honeycomb-shaped cells 5 are formed. As a general method for using the honeycomb-shaped three-dimensional reinforcing material 1, the honeycomb-shaped three-dimensional reinforcing material cell 5 is filled with a filling material up to the height of the cell and compacted, whereby a rigid honeycomb structure 9 is obtained. Let it form.

  As the filling material to be filled in the cell 5 of the expanded honeycomb-shaped reinforcing material, any soil material such as sand, earth and sand, crushed stone can be used, but in the case of the mattress method, the filling material is Crushed stone is preferred.

Next, the mechanism of the force that the structural load is applied to the ground will be described.
In FIG. 3, the concept of the load to the ground of a structure was shown. When the structure 6 is installed on the ground, the ground reaction force P is applied to the lower ground of the structure. Since the ground reaction force P is balanced with the support force q, the structure 6 can be kept stable. On the other hand, when the supporting force q is smaller than the ground reaction force P, the settlement of the structure 6 proceeds and the ground 7 is destroyed. When the supporting force q is smaller than the ground reaction force P, a replacement method is generally performed in which the lower part of the structure is replaced with high-quality sandy soil.

  Here, the support force q, the ultimate support force qu, and the allowable support force qa will be described. When a structure is constructed on the ground, a ground reaction force P that acts on the ground from the structure and a support force q that the ground reacts against the ground reaction force P appear on the ground. The limit support force with which the ground is supported with respect to the ground reaction force P is the ultimate support force qu. Further, the value obtained by dividing the ultimate support force qu by the safety factor Fs is the allowable support force qa. When the safety factor is 1, the values of the ultimate support force qu and the allowable support force qa are equal.

FIG. 4 shows the concept of load when the structure foundation is replaced with high-quality soil. As described above, the structure foundation is replaced with high-quality soil when the ultimate supporting force qu under the structure is smaller than the ground reaction force P. When the lower part of the structure 6 is replaced with good-quality sandy soil, the load is distributed to the internal friction angle of the sandy soil. When the structure foundation is replaced with high-quality soil, the ground reaction force P is reduced to σz due to the load dispersion effect of the high-quality soil. If σz is smaller than the ultimate support force qu, the structure can be supported. That is, the relationship between the ground reaction force P and the underground vertical stress σz (extreme support force qu) is generally expressed by the following equation.

σz = P / [1 + 2 · (z / B) tanθ] + γ · z Equation 1

Where σz: underground vertical stress (kN / m ² )
P: Ground reaction force per unit area (kN / m ² )
z: Depth from the foundation bottom plate of the structure (m)
B: Structure foundation bottom slab width (m)
θ: underground load distribution angle (°)
γ: Unit volume weight (kN / m ³ )

  The replacement method with high-quality soil for the structure foundation has the effect of reducing the ground reaction force P per unit area at the bottom of the high-quality soil layer by replacing the high-quality soil, and the reduced load per unit is smaller than the ultimate bearing capacity qu. By doing so, the uneven settlement of the structure does not occur. However, this construction method tends to increase the depth of replacement of high-quality soil, and the burden on civil engineering work is large.

Next, a method for using a honeycomb structure as a structure foundation will be described.
FIG. 5 shows an example in which the honeycomb structure 9 is installed under the structure 6 so that the structure 6 (box culvert or the like) constructed of concrete or the like does not cause uneven settlement. When the ground reaction force P of the structure 6 is larger than the ultimate support force qu of the ground 7, the honeycomb structure can be used as the structure foundation to ensure the ultimate support force qu. The honeycomb structure to be installed under the structure 6 may be a single layer or a plurality of layers. FIG. 5 shows an example of single layer laying.

FIG. 6 shows the concept of load when a honeycomb structure is used as the structure base. When the honeycomb structure is laid on the structure foundation, it is possible to estimate the increase in supporting force σR due to the honeycomb structure, and the ground reaction force P per unit area and the increase in supporting force σR due to the honeycomb structure. And the ultimate supporting force qu of the honeycomb structure bottom plate portion is expressed by the following relational expression.

P ≦ σR + qu (2)

However, P: Ground reaction force per unit area (kN / m ² )
σR: Increase in bearing capacity due to honeycomb structure (kN / m ² )
qu: Ultimate ground bearing capacity (kN / m ² )

In general, when performing ground improvement considering the bearing capacity of the structure foundation, a safety factor that is several times higher than the ground reaction force P is considered, and the allowable bearing capacity obtained by dividing the ground bearing capacity qu of the structure foundation by the safety factor Fs. A force qa is used. When the safety factor Fs is expected, the ground reaction force P per unit area, the bearing force increase σR / Fs by the honeycomb structure that allows the safety factor, and the allowable bearing force qa are expressed by the following relational expressions ( When the safety factor is 1, the ultimate support force qu and the allowable support force qa have the same value).

P ≦ (σR / Fs) + (qu / Fs) = (σR / Fs) + qa Equation 3

However, P: Ground reaction force per unit area (kN / m ² )
σR: Increase in bearing capacity due to honeycomb structure (kN / m ² )
qu: Ultimate ground bearing capacity (kN / m ² )
qa: Allowable bearing capacity of the ground (kN / m ² )
Fs: Safety factor

Next, a method for calculating the bearing capacity increase σR by the honeycomb structure will be described with reference to FIGS.
FIG. 7 is a cross-sectional view showing the concept of force transmission when a load is applied to the honeycomb structure from above. When the load q is applied to the honeycomb structure 9, the cells of the honeycomb structure 9 try to spread in the horizontal direction (horizontal stress σm), and at that time, the shear resistance τ between the cell wall 10 and the filling material The shear resistance τ acts as a resistance against the load q.

  When the load q is loaded on the filling material in the honeycomb structure 9, a shear resistance force τ proportional to the load q acts in the direction opposite to the load q. A value obtained by converting the shear resistance q into a unit area of the honeycomb structure 9 is σR.

The horizontal stress σm of the honeycomb structure 9 is defined as a force that causes the filling material to expand laterally when a load q is applied to the honeycomb structure 9, and is mainly related to the vertical stress σv that acts on the honeycomb structure. It is obtained by multiplying the working earth pressure coefficient Ka and is expressed by the following equation.

σm = Ka · σv Equation 4

However, Ka: main earth pressure coefficient Ka
σv: vertical stress generated in the cell (ground reaction force P) (kN / m ² )

The main earth pressure coefficient Ka is derived by the following formula from the relationship with the internal friction angle φ of the filling material filled in the honeycomb structure.

Ka = tan ² (45−φ / 2) Equation 5

The relationship between the shear resistance τ in the honeycomb structure 9 and the horizontal stress σm when the honeycomb structure 9 and the wall surface friction angle δ are expressed by the following equation.

τ = σm · tan δ Equation 6

Where σm: horizontal stress in the cell (kN / m ² )
δ: Wall friction angle between cell and filling material (°)

The wall friction angle δ was confirmed to be the same as the internal friction angle φ of the filling material by a large one-surface shear test.

  FIG. 8 is a plan view for explaining the concept of an increase in supporting force by the honeycomb structure. The increase in supporting force σR by the honeycomb structure is closely related to the height H and the cell size D of the honeycomb structure. The mechanism of the effect of increasing the supporting force will be described with reference to the assumed circle portion 11 in which the cells of the honeycomb structure 9 are considered to be circular, and the portion other than the assumed circle portion 11 (deemed valley portion 12).

According to FIG. 8, the range in which the supporting force is increased by the honeycomb structure is such that each cell of the honeycomb structure 9 is a circle having a diameter D circumscribed by the cell (deemed circle portion 11) and other than the deemed circle portion 11. It is approximated to a rounded rhombus-shaped portion (deemable valley portion 12, hatched portion in FIG. 8). Since the honeycomb structure installed under the structure receives the load of the structure on the surface, it can be approximated that two types of cell aggregates of the deemed circle portion 11 and the deemed valley portion 12 receive the load. . That is, the supporting force increase amount σR by the honeycomb structure is an average value of the supporting force increase amount σR1 of the assembly of the deemed circle portion 11 and the supporting force increase amount σR2 of the assembly of the deemed valley portion 12, and It is represented by

σR = (σR1 + σR2) / 2 Formula 7

However, σR1: Increase in bearing capacity of the aggregate of the deemed circle portion 11 (kN)
σR2: Increase in bearing capacity of aggregate of deemed valley portion 12 (kN)

  Next, the shear force generated in one cell is calculated by multiplying the shear force τ acting on the side surface (inner surface side) of the cells constituting the honeycomb structure by the side area (inner area) of one cell. . Furthermore, if the shear force is divided by the area of the cell, the shear force per unit area of the cell can be calculated.

FIG. 9 shows a perspective view (left) of the deemed circle portion 11 and a developed view of the circumferential portion of the deemed circle portion 11. Of one cell constituting the honeycomb structure, the shearing force of the deemed circle portion 11 (the supporting force increase σR1 of the aggregate of the deemed circle portion 11) is calculated as follows.
That is, σR1 is calculated by dividing the product of the side area A1 of the deemed circle portion 11 and the shear resistance τ by the area S1 of the deemed circle portion 11, and is expressed by the following equation.

σR1 = A1 · τ / S1 Equation 8

However, σR1: Increase in bearing capacity of the aggregate of the deemed circle portion 11 (kN)
τ: Shear resistance (kN)
A1: Side area of the deemed circle portion 11 (m ² )
S1: Area of the deemed circle portion 11 (m ² )

Further, the side area A1 of the deemed circle portion 11 and the area S1 of the deemed circle portion 11 can be calculated by the following equations.

A1 = πD · H Equation 9

S1 = πD ^2/4 ... formula 10

From the above, substituting Equation 8 and Equation 9 into Equation 7 leads to the following equation.

σR1 = 4 · τ · (H / D) Equation 11

In FIG. 10, the perspective view (left) of the deemed valley part 12 and the expanded view of the side part of the deemed valley part 12 were shown. Of one cell constituting the honeycomb structure, the shearing force of the deemed valley portion 12 (the increase in supporting force σR2 of the aggregate of the deemed valley portion 12) is calculated as follows. That is, σR2 is calculated by dividing the product of the side area A2 of the deemed valley portion 12 and the shear resistance τ by the area S2 of the deemed valley portion 12, and is expressed by the following equation.

σR2 = A2 · τ / S2 Equation 12

Where σR2: increase in bearing capacity of the aggregate of the deemed valley portion 12 (kN)
τ: Shear resistance (kN)
A2: Side area of deemed valley portion 12 (m ² )
S2: Area of the deemed valley portion 12 (m ² )

The side area A2 of the deemed valley portion 12 is calculated as follows. That is, the side surface portion of the deemed valley portion 12 is composed of four rounded rhombus-shaped portions having the same area as a quarter of the side area of the deemed circle portion 11. It is the same area as the side area. That is, it is expressed by the following formula.

A2 = (1/4) · π · D · H · 4 = π · D · H Equation 13

Next, the area S2 of the deemed valley portion 12 is calculated as follows. The area S2 of the deemed valley portion 12 is an area obtained by dividing four squares (quarter circles) of a circle having a radius (1/2) · D from a square having a side length of D by the following formula: It is represented by

S2 = D ² − [(1/2) D] ² · π / 4 · 4 = D · (4-π) / 4 Equation 14

From the above, when formulas 13 and 14 are substituted into formula 12 and rearranged, the following formula is derived.

σR2 = A2 · τ / S2 = 4 · τ · (H / D) [π / (4-π)] Equation 15

The average of the supporting force increase σR1 of the deemed circle portion 11 and the supporting force increase σR2 of the deemed valley portion 12 calculated by the above method is the supporting force increase σR by the honeycomb structure. Substituting Equation 11 and Equation 15 into Equation 7 and rearranging them leads to the following equation.

σR = (σR1 + σR2) / 2≈9 · τ · (H / D) (16)

Next, the design procedure of the honeycomb structure mattress method using the design method according to the present invention is performed in the following steps. First, the procedure for calculating the lack of support capacity is described.
1) Calculate the ground reaction force P applied to the ground when a structure is installed.
2) The ultimate bearing capacity qu of the ground is measured and determined by a flat plate loading test or the like.
3) The allowable bearing force qa is calculated by dividing the ultimate bearing force qu obtained from the measurement by the safety factor Fs set when the structure is installed.
4) By subtracting the allowable bearing force qa from the ground reaction force P, the insufficient bearing force (that is, equivalent to the bearing force increase σR / Fs by the honeycomb structure mattress method) is calculated.

Next, the main earth pressure coefficient Ka used for calculating the bearing capacity increase σR by the honeycomb structure mattress, the horizontal stress σm in the cell, and the calculation method of the horizontal stress σm in the cell will be described.

5) Calculation of main earth pressure coefficient Ka The inner friction angle φ of the filling material filled in the honeycomb structure is calculated, and the inner earth friction angle φ is substituted into the following formula to calculate the main earth pressure coefficient Ka.
Ka = tan ² (45 ° −φ / 2)
Where φ is the internal friction angle of the filling material filled in the honeycomb structure

6) Calculation of horizontal stress σm in cell The horizontal stress σm in the cell is calculated by substituting the main earth pressure coefficient Ka calculated in the above procedure into the following equation.
σm = Ka · σv
However, σv is the vertical stress generated in the cell, that is, the ground reaction force P

7) Calculation Method of Horizontal Stress σm in Cell The horizontal stress σm in the cell is calculated by substituting the horizontal stress σm in the cell calculated in the above procedure into the following formula. It has been confirmed by a large one-side shear test that the wall friction angle δ is the same value as the internal friction angle φ of the filling material filled in the honeycomb structure.
τ = σm · tanδ
Where δ is the wall friction angle between the cell and the cell filler

Next, a method for calculating the bearing capacity increase σR by the honeycomb structure mattress will be described.
Using the main earth pressure coefficient Ka obtained by the above procedure, the horizontal stress σm in the cell, and the horizontal stress σm in the cell, the bearing capacity increase σR is calculated as follows.

8) Calculation method of increase in bearing capacity σR σR = 2 · τ · (H / D) · [1 + π / (4-π)] ≈ 9 · τ · (H / D)
Where τ is the shear resistance of the cell
H is the height of the cells constituting the honeycomb structure
D is the diameter only when the cells constituting the honeycomb structure are regarded as circles.

At this time, the insufficient supporting force obtained in 4) (that is, the supporting force increase σR / Fs by the honeycomb structure mattress method) and the supporting force increase σR obtained in 8) are divided by the safety factor Fs. In comparison with the height H of the cell and only when the cell is regarded as a circle, the numerical value is substituted for the diameter D, and the increase in the supporting force σR / Fs by the honeycomb structure mattress method is larger than the insufficient supporting force. A trial is performed so that H and D are determined.

Next, the procedures for constructing the honeycomb structure mattress are the following procedures 1) to 4).
1) Select and prepare a honeycomb three-dimensional reinforcing material satisfying the diameter D only when the cell height H calculated by the above design method is considered as a circle and the cell is regarded as a circle.
2) Excavate the flooring part of the structure installation location to a depth where the height H of the cell fits.
3) The honeycomb-shaped three-dimensional reinforcing material is expanded, and the honeycomb structure is installed by filling the honeycomb-shaped three-dimensional reinforcing material with the filling material in the flooring portion of the structure installation location.
4) One or more layers of the honeycomb structure are installed until the height H is reached, and the honeycomb structure mattress is installed.

  In Examples 1 to 3, a honeycomb structure was installed on the ground, and a flat plate loading test based on the Japan Society for Geotechnical Engineering (JGS1521) was performed. As a comparative example, the same test was performed without installing anything on the ground.

  In FIG. 11, the conceptual diagram of the test in Examples 1-2 (especially FIG. 11 is the case of Example 2) was shown. FIG. 12 shows a photograph when the honeycomb structure is installed on the ground. FIG. 13 shows a photograph when a load is applied to the honeycomb structure from above.

  A load was applied from the upper part of Examples 1 and 2 and Comparative Example 1, and the load and the amount of displacement were measured. The experimental conditions at that time are shown in Table 1. A graph showing the relationship between the loading pressure P and the settlement amount S is shown in FIG. From the graphs, the ultimate supporting forces of actually measured values of Examples 1 and 2 and Comparative Example 1 were calculated.

The supporting force improvement effect σR of Examples 1-2 was calculated from the difference between the limiting supporting force of Examples 1-2 and the limiting supporting force of Comparative Example 1, respectively. That is, the increase in the supporting force of the actually measured value is calculated as follows.

Increase in bearing capacity of Example 1 = Ultimate bearing capacity of Example 1-Ultimate bearing capacity of Comparative Example 1

Increase in bearing capacity of Example 2 = Ultimate bearing capacity of Example 2-Ultimate bearing capacity of Comparative Example 1

The theoretical values σR of Examples 1 and 2 were calculated as follows.
The filling material filled in the honeycomb structures of Examples 1 and 2 was crushed stone, and the internal friction angle was φ = 35 °.
From Equation 5, the main earth pressure coefficient Ka is obtained from Equation 5 as follows.

Ka = tan ² (45−φ / 2) = tan ² (45−35 / 2) = 0.271

The vertical stress σv acting on the honeycomb structure was calculated at 90 kN / m ^{2 obtained} by dividing the ultimate supporting force of Example 2 by the safety factor 3. The vertical stress σv of 90 kN / m ² corresponds to a state in which a concrete structure having a height of about 4 m (unit volume weight is 22 kN / m ³ ) is loaded on the honeycomb structure.
The horizontal stress σm of the honeycomb structure 9 in the case of σv = 90 kN / m ² is obtained from Equation 4 as follows.

σm = Ka · σv = 0.271 × 90 = 24.39 kN / m ²

The shear resistance τ in the honeycomb structure 9 can be obtained from Equation 6 as follows. The wall surface friction angle δ of the honeycomb structure 9 is the same as the internal friction angle φ of the filling material, and φ = δ = 35 °.

τ = σm · tan δ = 24.39 × tan 35 ° = 24.39 × 0.7
= 17.07 (kN / m ² )

The increase in supporting force σR by the honeycomb structures of Example 1 and Example 2 is obtained from Equation 16 as follows.
In the case of Example 1, since the height H of the honeycomb structure is 0.15 m and the cell size (diameter) D≈0.3 m, σR (Example 1) of Example 1 is

σR (actual 1) = 9 · τ · (H / D)
= 9 × 17.07 × (0.15 / 0.3) = 76.8 (kN / m 2)

In the case of Example 2, since the height H of the honeycomb structure is 0.3 m and the cell size (diameter) D≈0.3 m, σR (Example 2) of Example 2 is
σR (actual 2) = 9 · τ · (H / D)
= 9 × 17.07 × (0.3 / 0.3) = 153.6 (kN / m 2)

The theoretical values of Examples 1 and 2 derived from the above were compared with σR derived from the plate loading test results. The comparison results are shown in Table 1. In both Example 1 and Example 2, the actually measured value σR and the theoretical value σR approximated each other.

By constructing the construction method of the honeycomb structure mattress construction method of the present invention, it is possible to obtain sufficient support force for the structure even if the replacement area and the replacement thickness are smaller than those of the conventional mattress construction method.

DESCRIPTION OF SYMBOLS 1 Honeycomb-shaped solid reinforcement 2 Strip material 3 Hole 4 Bonding part 5 Cell 6 Structure 7 Ground 8 Replacement part 9 Honeycomb structure 10 Cell wall 11 Only a honeycomb structure and a circular part 12 Only a honeycomb structure and a valley part 13 Loading board a Stretching direction X Cross section P Ground reaction force per unit area z Depth from structure foundation bottom B Structure foundation bottom width θ Ground load distribution angle q Bearing capacity qu Ultimate bearing force σz Vertical stress in the ground σR Increased bearing capacity due to honeycomb structure q Load D Diameter of honeycomb structure deemed circle H Height of honeycomb structure σm Horizontal stress τ Shear resistance in honeycomb structure 9

The invention described in claim 1
A strip material made of a plurality of long pieces of resin or fiber sheets is juxtaposed in the width direction on the foundation of the structure, and partially joined in a staggered manner at predetermined intervals, and this is orthogonal to the width direction. A honeycomb structure mattress construction method in which a honeycomb structure is formed by filling a honeycomb-shaped three-dimensional reinforcing material with a filling material to form a honeycomb-shaped cell by spreading on a honeycomb structure,
Compare the ground reaction force P with the allowable bearing force qa obtained by dividing the ultimate bearing force qu of the foundation ground by the safety factor Fs.
The deficiency of the allowable bearing force qa with respect to the ground reaction force P is supplemented by the bearing force increase σR / Fs by the honeycomb structure mattress installed on the structure foundation ,
A method for designing a honeycomb structure mattress method, wherein the steps of calculating the increase in supporting force σR by the honeycomb structure mattress are the following steps 1) to 4).
1) Calculation of main earth pressure coefficient Ka Ka = tan ² (45 ° −φ / 2)
Where φ is the internal friction angle of the filling material filled in the honeycomb structure 2) Calculation of horizontal stress σm in the cell σm = Ka · σv
However, σv is the vertical stress generated in the cell, that is, the ground reaction force P
3) Calculation of shear resistance τ of cell τ = σm · tanδ
However, δ is the wall friction angle between the cell and the filling material of the cell. 4) Calculation of the increase in bearing force σR σR = 2 · τ · (H / D) · [1 + π / (4-π)] ≈ 9 · τ・ (H / D)
Where τ is the shear resistance of the cell
H is the height of the cells constituting the honeycomb structure
D is the diameter only when the cells constituting the honeycomb structure are regarded as circles.

The invention according to claim 2
Is the design method of the honeycomb structure mattress method of claim 1 wherein the wall friction angle δ is equal to the internal friction angle φ of Chutsume material to be filled in the honeycomb structure of the filling material in said cell and a cell .

The invention described in claim 3
The height H of the cells constituting the honeycomb structure calculated by the design method according to claim 1 or 2 , and the diameter D only when the cells constituting the honeycomb structure are regarded as a circle,
A process of selecting a honeycomb-shaped three-dimensional reinforcing material,
A step of excavating the flooring portion of the structure installation location to a depth where the H can be accommodated;
Extending the honeycomb-shaped three-dimensional reinforcing material, filling the honeycomb-shaped three-dimensional reinforcing material with the filling material, and installing the honeycomb structure;
Including the step of installing the honeycomb structure mattress by setting one or more layers of the honeycomb structure until the height H is reached,
This is a construction method of the honeycomb structure mattress construction method.

Claims (4)

A strip material made of a plurality of long pieces of resin or fiber sheets is juxtaposed in the width direction on the foundation of the structure, and partially joined in a staggered manner at predetermined intervals, and this is orthogonal to the width direction. A honeycomb structure mattress construction method in which a honeycomb structure is formed by filling a honeycomb-shaped three-dimensional reinforcing material with a filling material to form a honeycomb-shaped cell by spreading on a honeycomb structure,
Compare the ground reaction force P with the allowable bearing force qa obtained by dividing the ultimate bearing force qu of the foundation ground by the safety factor Fs.
A design method for a honeycomb structure mattress construction method, wherein a deficiency in the allowable bearing force qa with respect to the ground reaction force P is compensated by a supporting force increase σR / Fs by a honeycomb structure mattress construction method installed on a structure foundation. The method for designing a honeycomb structure mattress construction method according to claim 1, wherein the step of calculating a supporting force increase σR by the honeycomb structure mattress is the following steps 1) to 4).
1) Calculation of main earth pressure coefficient Ka Ka = tan ² (45 ° −φ / 2)
Where φ is the internal friction angle of the filling material filled in the honeycomb structure 2) Calculation of horizontal stress σm in the cell σm = Ka · σv
However, σv is the vertical stress generated in the cell, that is, the ground reaction force P
3) Calculation of shear resistance τ of cell τ = σm · tanδ
However, δ is the wall friction angle between the cell and the filling material of the cell. 4) Calculation of the increase in bearing force σR σR = 2 · τ · (H / D) · [1 + π / (4-π)] ≈ 9 · τ・ (H / D)
Where τ is the shear resistance of the cell
H is the height of the cells constituting the honeycomb structure
D is the diameter only when the cells constituting the honeycomb structure are regarded as circles.   The method for designing a mattress construction method for a honeycomb structure according to claim 2, wherein a wall friction angle δ between the cells and the filling material of the cells is the same value as an internal friction angle φ of the filling material filled in the honeycomb structure. The height H of the cells constituting the honeycomb structure calculated by the design method of claims 1 to 3, and the diameter D only when the cells constituting the honeycomb structure are regarded as a circle,
A process of selecting a honeycomb-shaped three-dimensional reinforcing material,
A step of excavating the flooring portion of the structure installation location to a depth where the H can be accommodated;
Extending the honeycomb-shaped three-dimensional reinforcing material, filling the honeycomb-shaped three-dimensional reinforcing material with the filling material, and installing the honeycomb structure;
Including the step of installing the honeycomb structure mattress by setting one or more layers of the honeycomb structure until the height H is reached,
Construction method of honeycomb structure mattress construction method.