JP3136315B2 - A computer-readable medium storing a ground design strength calculation system and a ground design strength calculation program - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a design ground strength calculation system for calculating the strength of the ground which is the basis for building a building or the like, and a computer readable medium storing a design ground strength calculation program for the ground.

[0002]

2. Description of the Related Art The basic design of a building, especially a low-rise building such as a residential building, is based on data obtained by conducting a ground survey of the building site, and the specifications of the foundation of the planned building and the load are supported by the ground. A method is considered to determine whether it is safe against force and subsidence.

In such a method, every time the shape or load of the foundation is changed or changed, it must be examined whether or not the ground is safe.

In the case of a two- or three-story foundation for a detached house, the base width of the applicable foundation (width of the bottom of the foundation)
Because there are many types of relationships between the load and the load, even the same wooden two-story building can be safe or dangerous if the foundation width differs by only a few centimeters. Originally, the bearing capacity of the ground and the amount of settlement are not so precise and accurate, so it is not appropriate to consider the ground safety based on the base width and load of the foundation.

[0005] foundation, even in the building, also a workpiece, such as a retaining wall, set the design area strength is what t / m ^2, on the grounds that it more bearing capacity expected Although it is judged that it can be used for this purpose, there is no known method for directly calculating the important soil bearing capacity.

[0006] In the ground survey, a rod having a screw point attached to its tip is rotated by applying a predetermined load to the head, and the amount of penetration is measured. (A parameter representing hardness and softness).

[0007] The ground survey method using the Swedish sounding method was described on January 30, 1993.
Published by the Japan Society of Geotechnical Engineers (currently the Geotechnical Society)
Please refer to.

[0008]

Conventionally, although the term "ground strength of ground" has been used, there has been no method for calculating a clear numerical value. Therefore, not the settlement amount but the bearing capacity itself is generally used as the ground strength. Have been. Since the failure of the building due to uneven settlement is caused by settlement rather than the bearing capacity, it is possible to select a safe foundation if the ground strength taking into account the settlement amount is determined by the ground. Become.

[0009] Recently, general ground diagnosis has been conducted by examining both the settlement amount and the bearing capacity. However, there are various formulas for calculating the settlement amount, and depending on which calculation formula is used,
Since the amount of settlement varies depending on the shape of the foundation and the contact pressure (design ground strength), it is necessary to input and consider the designer's basic specifications each time.

[0010] Further, since the base width of the foundation and the proof strength of the design site differ depending on the builder such as a house maker or a construction shop, and furthermore, depending on the scale of the building, every time the scale of the builder or the building is changed, it changes. Must be considered whether it is safe for the ground.

FIG. 22 is an explanatory diagram of a conventional base selection method. In the drawing, GL indicates the surface level of the ground (ground line), BS indicates the foundation, B indicates the foundation width (base width), q indicates the load, and RF indicates the reinforcing member. Ground survey
First, for the planned foundation (foundation of the type to be adopted), consider the bearing capacity and the amount of settlement, and if you are concerned about safety, expand the width of the foundation with the cloth foundation shown in Fig. (A). To reconsider or otherwise consider reinforcing the foundation. Further, in the case of the solid foundation shown in FIG. 3B, since the range under the foundation on which the load q is applied is not clear, it is difficult to examine the bearing strength and the amount of settlement.

That is, even if the foundation of a detached house is a cloth foundation, the foundation width B is 360 mm or 450 m.
m, or 600 mm because it is not a fixed size,
When considering safety from basic specifications, the same building is repeatedly examined. For example, when the foundation width B is 360 mm and the design bearing capacity is 5 t / m ² , the load of the building on the foundation is 1.8 t / m (=
5t / m ² × 0.36m), but with a building of the same scale and structure, the base width B is 450m
Once the design land yield strength of the 5t / m ² in m, the load of the building in basic street 2.25t / m (= 5t / m 2 × 0.
45m), so in the ground diagnosis, it is necessary to consider in consideration of the foundation width B of each planned foundation and the designed ground strength.

If a two-story building is considered and a three-story building is changed, the ground specifications will naturally differ, and the ground safety will be reviewed again. At present, there is no calculation method for calculating the ground strength that is the basis for the safety judgment of the building on the ground of the site, and the judgment is made based on the bearing capacity and the amount of settlement. The "Terzaggi's formula" is commonly used for the bearing capacity, but there is no such commonly used formula for the amount of settlement.

Article 38 of the Ordinance for Enforcement of the Building Standards Law stipulates that the foundation of a building must be structurally durable against subsidence or deformation of the ground. There are no clear criteria.

The conventional calculation of the soil bearing strength is empirically performed based on the specification of the foundation shape and the "N value" obtained from the ground. Therefore, ultimately, the skill of the designer and the can are relied on. It was impossible to calculate the bearing capacity objectively.

If the bearing capacity can be objectively calculated from the results of the ground survey before the basic specifications are determined, it is possible to determine the basic specifications corresponding to the ground strength and to increase the foundation width. It is possible to determine in advance whether the ground is necessary, and it is possible to determine an economical and safe basic specification. However, as described above, since a method of directly calculating the ground bearing capacity of the ground was not known, such a method was conventionally impossible.

Accordingly, a first object of the present invention is to provide a ground design capable of objectively calculating a ground bearing from an "N value" obtained by a survey result of the ground by a Swedish sounding method before determining basic specifications. It is an object of the present invention to provide an earth bearing capacity calculation system. Further, a second object of the present invention is to provide a program for using the above-mentioned ground design strength calculation system which can be easily executed by a general-purpose computer regardless of the place. It is an object of the present invention to provide a computer-readable medium recording an execution program for operating a calculation system.

[0018]

[Means for Solving the Problems] Since the bearing capacity is a numerical value that indicates the strength of soil that is safe against bearing capacity and settlement, the numerical value that is safe by examining the supporting capacity and studying for settlement is determined. Have to find out. In the present invention, the load (ground pressure) of a building that is unsafe (= NO) is calculated in consideration of the bearing capacity, and is not safe (= N) in consideration of settlement.
O) Calculate the load when it becomes, and let the smaller one be the ground bearing capacity of the ground. It is assumed that buildings with a design ground bearing capacity lower than this ground strength are safe.

If the shape of the foundation is not set, each examination cannot be performed. Therefore, the shape of the foundation (general-purpose foundation) where the settlement amount hardly changes is set. This general purpose foundation
The base width B and the base length L were each set to 20 m 2
A solid base of 0 m x 20 m is used.

FIG. 1 is a diagram for explaining the principle of a method for calculating the design ground strength of a ground according to the present invention. In the figure, the same reference numerals as those in FIG. 22 correspond to the same parts. That is, the ground survey is carried out by using the “ground design ground strength calculation program” of the present invention, which will be described below and described in detail in Examples below, to determine the designed ground strength of the ground, and to determine the numerical value of the determined designed ground strength. The following foundations are selected from the existing foundation group. At this time, it is not necessary to study the selected foundation as described with reference to FIG. In addition, a foundation having a desired strength is obtained by examining the foundation reinforcement based on the determined design land strength.

[0021] The execution program of the system for calculating the design ground strength of the ground according to the present invention is for obtaining the allowable value of the bearing capacity and the settlement amount, that is, the ground strength, depending on the hardness of the ground, so that a safe foundation suitable for the ground concerned is obtained. Can be selected. Regardless of the relationship between the shape of the foundation and the load, the ground strength can be safely constructed by using a foundation having a calculated ground strength or less.

Therefore, even if there is a change in the building or foundation shape (number of floors, structure, foundation width, load, etc.),
There is no need to consider the safety of the ground. In the prior art, even if the ground is safe for a two-story building, it is necessary to consider again whether or not the ground is safe when changing to a three-story building. If it is known, even if it is a three-story building, only the foundation below the calculated soil bearing capacity is used, and the above examination is not necessary.

The "ground soil strength calculation program" according to the present invention can be calculated only by the "N value" obtained by the Swedish sounding method described above. There is no need to determine the force or internal friction angle, and the building designer can select a safe basic specification without worrying about examining the foundation for the ground.

That is, in order to achieve the first object, the present invention provides a ground condition data file for storing soil conditions of a ground, a basic dimension data file for storing general-purpose basic dimensions, and a Swedish sounding test. An "N value" data file for storing the collected "N values" for a plurality of depths under the foundation, a supporting force data file for storing the supporting force of the ground, a subsidence data file for storing the subsidence amount of the ground, And a plurality of depths under the ground based on the ground condition data file, the basic dimension data file and the data stored in the "N value" data file.
Repeatedly add the load of the specified size every time and set in advance
From the load when the supporting force becomes larger than
The load obtained by subtracting the load of the specified magnitude
Stored in the supporting force of the data file as data, before
Addition of load of specified size at multiple depths below the foundation of the ground
Is repeated until the settled amount at that time is set in advance.
From the load when the load exceeds
The settled weight is used as the allowable stress data.
The allowable bearing force data and the allowable stress data stored in the bearing force data file and the sinking amount data file are stored, and the smaller one is used as the design ground bearing data of the ground. And a calculating means for storing in the.

The soil conditions of the ground include soil soil (cohesive soil / sandy soil) of the ground, sedimentation thickness of loam layer, sedimentation thickness of galley, presence / absence of embankment / soil quality, and the like. As described above, as the general-purpose basic dimensions to be stored, a foundation having a shape in which the settlement amount hardly changes, for example, a solid foundation having a width of 20 m and a length of 20 m is input as a general-purpose basic (standard basic) dimension.

The "N value" data file stores numerical values ("N value") at a plurality of depths below the foundation collected by performing the above-mentioned swedish sounding test on the ground on which a building is to be built.

The calculating means is configured to calculate the bearing strength of the ground at each of a plurality of depths beneath the foundation, the measurement points, and the measurement points based on the data stored in the ground condition data file, the foundation dimension data file, and the “N value” data file. The maximum squat amount is calculated and stored in the supporting force data file and the squat amount data file, respectively, and the supporting force data file and the squat amount data stored in the squat amount data file are compared with each other. The smaller one is stored in the ground strength data file as the designed ground strength of the ground.

The architect designer arbitrarily selects a foundation that is equal to or less than the design ground strength stored in the above-mentioned ground strength data file from among various types of foundations prepared in existing shapes and dimensions, and instructs the local builder. do it.

Also, in order to achieve the second object,
The present invention includes a step of storing a soil condition of a ground in a ground condition data file, a step of storing a general-purpose basic dimension in a basic dimension data file, and an “N value” for each of a plurality of sub-foundation depths collected in a Swedish sounding test. Is stored in an “N value” data file; and, based on the data stored in the ground condition data file, the basic dimension data file, and the “N value” data file , a predetermined Of magnitude load
Repeat the addition and it becomes larger than the preset support strength
From the load at the time of
The load obtained by subtracting the load is used as the allowable load data.
And storing the data file, the basis of the ground
Repeated addition of load of specified size for each lower multiple depth
And the amount of settlement at that time exceeds the amount of settlement set in advance.
Subtract the load of the specified magnitude from the above load
The settling amount data file is used as the allowable stress data.
Storing the allowable bearing force data file and the allowable stress data stored in the bearing force data file and the squat amount data file.
As a result of the comparison, the smaller one is the design ground strength of the ground.
Storing the data as the data in the ground strength data file. The program for causing a computer to execute the method for calculating the design ground strength of the ground, the program being recorded on a computer-readable medium.

By setting this medium in the input means of a general-purpose computer, the above-mentioned design proof stress can be calculated easily and quickly.

Although this medium is generally a so-called floppy disk (FD), it is not limited to this, and any type of known computer-readable medium can be used.

The present invention is not limited to the above means, and it goes without saying that various modifications can be made without departing from the technical idea of the present invention.

[0033]

Embodiments of the present invention will be described below in detail with reference to examples.

FIG. 2 is a block diagram for explaining an example of the system configuration of a computer for executing the program for calculating the design strength of ground of the present invention. In the figure, 1 is a central processing unit (CPU), 2 is a read-only memory (ROM) storing a basic control program of a computer, etc., 3 is a working write / read memory (RAM), 4 is a CRT or LCD, and others. Display unit (DP
L), 5 is an input unit, 5a is a keyboard (K
B) and 5b are pointing devices such as a mouse (PO
INT), 6 is a floppy disk drive (FD)
D) and 7 are file units suitable for a hard disk, 7a is a ground condition data file, 7b is a basic dimension data file, 7c is an "N value" data file,
7d is a bearing capacity data file, 7e is a settlement data file, and 7f is a ground bearing data file.

The above-mentioned CPU1, ROM2, and RAM3 constitute arithmetic means, and include a floppy disk drive (FDD).
The program recorded on the floppy disk set in 6 is executed. This program may be stored in a file unit 7 such as a hard disk with a program area provided.

FIG. 3 is a data input screen displayed on the display unit 4 when the ground design strength calculation program according to the present invention is started, and corresponds to each item of the template illustrated using the keyboard 5a and the pointing device 5b. Enter the data.

In the items of the survey subject and the survey place, the type of the building and the local location are input. In the soil item, enter "1" for cohesive soil and 2 for sandy soil. As a result, in the case of cohesive soil 1.6t / m ^3, in the case of sandy soils are displayed weight of 1.8 t / m ³ and soil.

In the item of ROHM, the thickness from the upper part (GL- × m) to the lower part of the thickness of the ROHM layer is input. Similarly, if there is a garbage, and if there is an embankment, enter the thickness of each type (cohesive or sandy soil). As for the embankment, the input thickness of the embankment is converted into a numerical value used for calculation and displayed. That is, when a numerical value is input to the embankment, the embankment is automatically calculated by (input value / 0.25 rounded up) × 0.25 and displayed as xxm. As the embankment soil type, the type of the embankment soil is input, and xxt / m ³ is displayed in the same manner as the above-mentioned soil quality.

When a numerical value is input to the depth Df of the lower surface of the foundation,
In calculation, Df is (input value / 0.25 rounded up) × 0.25
And is displayed as xxm. As the base width B and the base length L, 20 of the above-mentioned general-purpose dimension is input.

The above numerical values are standard values. In particular, in the case of 0.25, the "N value" is measured every 0.25 m, and the lower surface of the foundation is set to about GL-0.3 m. This is based on the fact that it can be changed.

FIG. 4 is an explanatory diagram of an "N value" input screen.
For a plurality of measurement points A, B, C, D, E,..., The “N value” actually measured by the Swedish sounding method is input. In the Swedish sounding method, when the rod cannot penetrate and the “N value” is 15, the “N value” is set to 15 for all the lower layers. If "N value" is set to 15, "N value" is automatically input as 15 up to 5 m. In addition, measurement points that cannot be penetrated due to moths or the like are not input. “N value” is 15
Is the limit for the Swedish sounding method.

The CPU 1 executes the ground condition data file 7a
Based on the data stored in the foundation dimension data file 7b and the "N value" data file 7c, the bearing capacity at each depth of 0.25 m below the foundation of the ground, the measurement point, and the maximum subsidence amount between the measurement points are calculated. The calculated values are stored in the supporting force data file 7d and the settlement data file 7e.

Thereafter, the CPU 1 compares the bearing strength data stored in the bearing strength data file 7d and the settlement amount data file 7e with the settlement amount data and determines the smaller one as the design ground strength of the ground in the ground bearing data file 7f. It is stored and displayed on the display unit (DPL) 4.

Based on the numerical value of the design ground strength, a foundation having the design ground strength or less is selected from various types of foundations prepared in existing shapes and dimensions. At that time, the shape and dimensions of the foundation are arbitrary.

Next, the procedure (program) for calculating the above-mentioned design ground strength will be described in detail.

FIG. 5 is a flowchart showing the entire flow of the program for calculating the design strength of the ground according to the present invention. First, this program is started, and ground conditions are input from the input screen shown in FIG. 3 (S-1). Then, "N value" is input from the input screen of FIG. 4 (S-2). This “N value” is a value that has been previously measured and tabulated by the Swedish sounding method.

After the input of each data, first, the supporting strength of the ground is examined (S-3). See Fig. 6 for an examination of the ground bearing capacity.
As will be described in detail below, the magnitude of the load q and the ground support force fe are compared from the foundation below 1.5 m (S-4), and the ground support force and the load are compared (S-5). In the case of “supporting force ≧ load” (YES), 0.1 t / m ² is added to the load (S-6), and the process is repeated until “ground supporting force <load”.

If "ground support force <load" is satisfied (NO), the amount of settlement is examined (S-8). If the permissible bearing capacity of the ground: fe1 is (q−0.1) t / m ² , the design ground strength determination step of the ground (S-1)
Go to 5) (S-7).

The study of the settlement amount will be described in detail with reference to FIG.
The subsidence amount up to 5.0 m is calculated (S-9), and the subsidence amount is an intermediate value of the maximum allowable relative subsidence amount of 4.0 to 6.0 cm of the "Architectural Foundation Structural Design Guideline" of the Architectural Institute of Japan. 0.0cm
Is compared as a standard (S-10), and the amount of settlement is> 5.0 cm.
If it is below (NO), 0.1 t / m ² is added to the load (S-11), and the process is repeated until the sinking amount becomes more than 5.0 cm.

In step (S-10), the amount of settlement> 5.0c
m (YES), the allowable stress: fe2 becomes (q
−0.1) t / m ² (S-14), and go to the ground design strength determination step (S-15).

In the study of the settlement amount, the difference of the maximum settlement amount between the measurement points is calculated (S-12). The difference between the maximum subsidence amounts is from 2.0 to 3.0 cm to 2.0 cm, the standard land of the allowable relative subsidence amount according to the "Architectural Foundation Structural Design Guidelines" of Architectural Institute of Japan
(S-13), and when the difference in the amount of settlement is> 2.0 cm (YES), the allowable stress degree: fe2 is (q-0.
1) Assuming t / m ² (S-14), go to the step of determining the designed ground strength of the ground (S-15).

Determining the design strength of the ground (S-1)
In 5), the allowable bearing capacity: fe1 obtained in step (S-7) is compared with the allowable stress degree: fe2 obtained in step (S-14), and the smaller one is designed for the ground. Earth bearing capacity.

FIG. 6 is a flowchart for explaining the details of the procedure for examining the supporting force according to the present invention. First, the depth D of the lower surface of the foundation, that is, the root bottom of the foundation is set to GL-0.5 m (S
-21), allowable ground strength (long-term allowable strength) q
a is calculated (S-22), and the calculated value is recorded.

Next, the standard load q (= 0.1 t / m ² ) is added to calculate the underground stress q ′ (S-24), and the calculated value is recorded. If the calculated underground stress q ′ is smaller than the allowable ground support qa from the foundation to 1.5 m (YES), 0.1 t / m ² is added to the load q (S
−26), and calculate the underground stress q ′ at that time (S-2).
4) Record. This is repeated, and when the underground stress q ′ becomes larger than the allowable bearing capacity qa of the ground (NO),
Add 0.25 m to the depth D of the root bottom of the foundation (S-2
7), Step (S-28) → (S-24) until the depth D of the root bottom of the foundation exceeds 1.0 m (S-28).
→ (S-25) → (S-27) → (S-28) is repeated.

[0055] When the depth D of Excavation bottom of the foundation exceeds 1.0 m, the value (q-0.1) t / m 2 by subtracting the 0.1 t / m ² from the load q at that time The permissible bearing strength fe1 of the ground is set (S-29).

FIG. 7 is a flowchart for explaining the details of the procedure for studying the settlement amount according to the present invention. First, the depth D of the lower surface of the foundation, that is, the root bottom of the foundation is set to GL-0.5 m (S-
31) A standard load q (= 0.1 t / m ² ) is applied (S-32). The settlement amount Si (cm) between each measurement point is calculated from the base to GL-5.0 m (S-33), and the calculation result is recorded.

The settlement amount Si (cm) is compared with the allowable value of 5.0 cm (S-34), and the settlement amount Si (cm) is set at the allowable value of 5.0 cm.
When it does not exceed 0 cm (NO), the load q is 0.1 t / m.
² is repeated by adding (S-35), and the calculated settlement amounts Si are recorded.

In step (S-34), the settlement amount Si (c
m) exceeds the allowable value of 5.0 cm (Y
ES) adds 0.25 m to the depth D of the root bottom of the foundation (S-36). Also, after the processing of step (S-33), the difference in the settlement amount between the current measurement point and the previous measurement point (Si-
When (Si _-1 ) exceeds the allowable value of 2.0 cm, (S-3)
8) Go to step (S-36).

In step (S-36), after adding 0.25 m to the depth D of the root root, the step (S-3)
While the depth D of the root bottom of the foundation does not exceed 1.0 m in the judgment of 7) (NO), go to step (S-35) and add 0.1 t / m ² to the load q (S-35). 35) and repeat the processing from step (S-33).

If the depth D of the root root of the foundation exceeds 1.0 m in the judgment of step (S-37), a value obtained by subtracting 0.1 t / m ² from the load q at that time ( q-
0.1) Let t / m ^{2 be} the allowable stress fe2 of the ground.

FIG. 8 is a flowchart for explaining the details of the procedure for determining the allowable stress fe2 in FIG. First, when the load q is (q = 0.1 t / m ² ), the difference between the maximum settlement amounts between the measurement points> the allowable value (2.0 cm) is satisfied (S-41).
Is fe2 as 0, and the load q when the difference between the maximum squat amounts between the measurement points> the allowable value (2.0 cm) is not (q = q + 0.1
t / m ² ), the difference in the maximum settlement between the measurement points>
If it is the allowable value (2.0 cm) (S-42), fe2
Is 1. Hereinafter, when the difference between the maximum squat amounts between the measurement points> the allowable value (2.0 cm) is not satisfied, the load q is set to 0.
It is determined whether or not the difference between the maximum squat amounts between the measurement points> the permissible value (2.0 cm) is determined by sequentially adding 1 t / cm ² (S-43) (S-4i).

The allowable stress fe2 thus calculated is compared with the allowable bearing force fe1 (step (S-1) in FIG. 5).
5)), the smaller one is defined as the design ground strength of the ground.

FIG. 9 shows the "N value" used in the present invention.
It is explanatory drawing of an example of a table. This "N value" table is a table prepared by measuring the ground of cohesive soil at the three measurement points A, B, and C by the Swedish sounding method, and shows the penetration depth of the rod (m ) Is shown along with a graph at each measurement point measured from GL until the “N value” becomes 15 in increments of 0.25 m.

FIG. 10 is an explanatory diagram of a use mode of the result calculated by the ground design strength calculation program according to the present invention.
As a result of calculation using the obtained “N value” by the program for calculating the design strength of the ground, 3.3 t / m ² was obtained as shown in FIG. Then, after the decimal point was cut off, the design ground strength was determined to be 3.0 t / m ² .

As shown in FIG. 6B, when there are two types of the 5.0 t / m ² specification and the 3.0 t / m ² specification each as a basis, the above-mentioned design ground strength 3.0 t / m 2 is obtained. Based on ² , select one of the foundations of the 3.0 t / m ² specification.

As described above, if the standard basic specifications are determined, the designer can easily set the basics simply by selecting an appropriate one from the specifications.

As described above, the program for calculating the design ground strength of the ground according to the present invention provides a load of a certain magnitude (in the embodiment,
0.1 t / m ² as a standard) is gradually applied to the ground, and a value obtained by subtracting a predetermined value (in the embodiment, 0.1 t / m ² ) from the value at the time when the ground is destroyed in terms of supporting force is used as the value. As the allowable stress of the ground, a load of the same magnitude (same as above) is gradually applied to the ground, and the value obtained by subtracting a predetermined value (same as above) from the value when the settlement amount exceeds the allowable value is the allowable stress of the ground. As a degree, the smaller one of the two is taken as the design ground strength of the ground.

As a standard method of applying a load, in the present embodiment, the above-mentioned 0.1 t / m ² is sequentially added. The base for the addition is based on the aforementioned 20 m × 20 m bottom plate (the lower surface of the foundation) as a standard when the settlement amount hardly changes when a load is applied to the same ground. The size of the foundation is not limited to this, and may be any size as long as the amount of settlement does not substantially change when a load is applied to the same ground.

The range of study of the bearing capacity is set to a standard up to 1.5 m below the foundation, depending on the scale and structure of a detached house. The long-term allowable bearing capacity qa of the ground can be obtained from Notification 11 of the Ministry of Construction.
According to the following formula of No. 1.

Q _a = 1/3 (α · C · N _C + β · γ ₁ · B · N _r + γ ₂ · D _f · N _q ) (t / m ² ) (1) where , Q _a : Long-term allowable bearing capacity of the ground (t / m ² ) C: Adhesive strength of the soil (t / m ² ) = “N value” × 10/16 as standard (from soil survey training book) γ ₁ : Unit volume weight of the ground below the bottom of the foundation (t /
m ³ ) γ ₂ : Unit volume weight of the ground above the base bottom (t /
m ³ ) D _f : Depth of embedding of foundation (m) α, β: Coefficient determined by foundation shape (α =
1.0 is standard).

N _c , N _r , N _q : Supporting force coefficient determined by the internal friction angle of the ground Internal friction angle φ: φ = (20 · N value) ^1/2 +15, where 0 is standard for cohesive soil .

In the case of sandy soil, qa = 0.8 · N value + ／ (γ2 · Df · Nq) rather than using qa as it is
Is more appropriate empirically, so this is the standard. Gala is not the "N value" of the soil itself,
The standard "N value" of the gala part is 2 or 3 as the buried soft ground. The “N” value of ROHM is standardized as “N” value × 2.0.

The underground stress of the load is determined by the rectangular division method based on the distributed load according to the Architectural Institute of Japan's "Guidelines for Designing Basic Building Structures".

FIG. 11 is an explanatory diagram of a rectangular division method for calculating the underground stress. FIG. 3A shows a width B and a length L.
(B) is a schematic view of a rectangular base bottom surface.

The underground stress is calculated by dividing the base bottom (four in the figure) and, as shown in FIG. 4B, (underground stress at point E) = (underground stress at point E). (Stress degree) × 4. Since the stress level at the center is maximized, it is standard to study at the center of the bottom of the foundation. The following equation is used to calculate the underground stress.

Δσz = q / 2π ｛[mn / (m ² + n ² +1) ^1/2 ] ·
(m ² + n ² +2) / (m ² +1) (n ² +1) + sin ^-1 mn / (m ² + n ² +1)
^1/2 ｝ (t / m ² ) where, Δσz: Underground stress at depth z from the foundation (t / m ² ) q: Uniformly distributed load (t / m ² ) m: m = B / z n: n = L / Z B: Short side of base bottom (base width) (m) L: Long side (length) of base bottom plate (m) The amount of settlement is calculated by De Beer (Dubier)
According to the following formula: ^{_{S = 0.4∫ 0 h (P1 /}} N) log (P2 / P1) d
h: (cm) where: S: amount of settlement (cm) N: “N value” P1: effective loading pressure (kg / cm ² ) P2: stress after loading (kg / cm ² ) h: layer for which the amount of settlement is determined Thickness (cm) The following conversion values are empirically used.

For soft ground up to 2.0 m, the settlement is 1.8 times the calculated value. For good ground up to 2.0 m, the settlement is 0.8 times the calculated value, 2.0 m to 5.0 m. For soft ground, the settlement is 1.2 times the calculated value. For good ground from 2.0m to 5.0m, the settlement is 0.6 times the calculated value. .6 times.

FIG. 12 is an explanatory diagram of the comparison of the settlement amount due to the change of the basic shape, in which the horizontal axis represents the base bottom (the basic width (= short side) Bm when the long side L = 20 m) and the vertical axis represents the settlement. Quantity (c
m).

As shown in the figure, when the base width B exceeds 5 m, the change in the amount of settlement is reduced regardless of the long side.
It becomes 6.90 at 20 m. B × L is 100m × 100m
Considering that the amount of settlement is 6.92 when B × L is set to 20 m × 20 m as a standard base dimension, the base can be used as a versatile base. The dimensions were 20 m × 20 m.

Next, the study of the above-mentioned bearing strength and settlement amount will be further described.

(1) Investigation of Support Strength FIG. 13 is an explanatory diagram of a method of studying the support strength. First, a load q of 0.1 t / m ² (standard) is applied to the ground, and it is determined whether the underground stress q ′ at that time is equal to or less than the long-term allowable bearing capacity qa of the ground 1.5 m (standard) under the foundation. Check up to
When the long-term allowable bearing capacity qa of all the grounds is larger, the same examination is performed by further adding 0.1 t / m ² .
The study is terminated when the underground stress q ′ becomes larger. That is, the examination is stopped when qa ≦ q ′,
Let the permissible bearing capacity of the ground at that time be (q-0.1) t / m
^{Assume 2} .

(2) Consideration of Settlement Amount FIG. 14 is an explanatory diagram of a method of studying the settlement. First 0.
A load q of 1 t / m ² (standard) is applied to the ground, and GL−
It is checked whether the settlement amount to 5.0 m (standard) is less than the allowable settlement amount.
The same examination is performed by adding 1 t / m ^2, and the operation is stopped when the settled amount is exceeded. That is, when the settlement amount Scm exceeds the allowable value of 5.0 cm or the difference of the maximum settlement amount between the measurement points exceeds the allowable value of 2.0 cm, the examination is stopped, and the allowable stress of the ground at that time is changed to (q −0.1) t / m ² .

Then, the allowable stress levels of the above (1) and (2) are compared, and the smaller one is defined as the designed ground strength of the ground.

FIG. 15 is an explanatory diagram of a method for examining the support strength and the amount of settlement with or without reinforcement. In the figure,
(A) shows the case without the groundwork reinforcement, and (b) shows the case with the groundwork reinforcement. When only the ground directly below the foundation is soft ground, 25cm is standard as the range of the ground work reinforcement, and if the soft ground is strengthened by the land work (reinforcement with compaction, chestnut stone, crushed stone, etc.), Since the designed ground strength of the ground can be expected to be larger, the designed ground strength of the ground when the ground work is reinforced is separately calculated. In this calculation method, the same calculation as when examining from the foundation is performed, but the bearing capacity and the amount of settlement are calculated from the soft ground 25 cm below the foundation as shown in FIG. I do.

FIG. 16 is an explanatory diagram of a calculation example of the supporting force and the settlement amount depending on the presence or absence of the groundwork reinforcement. In this calculation example,
The measurement was performed at three points A, B, and C. The calculated value of the design ground strength when there was no ground work reinforcement was 2.4 t / m ² , but the calculated value of the design ground strength when the ground work was reinforced from under the foundation to GL-0.75 m was 4.7 t. / M ² .

FIG. 17 is an explanatory diagram of the result of comparison between the values calculated by the program for calculating the design strength of the ground according to the present invention and the measured values. In the figure, the horizontal axis shows the measured value (cm) of the differential settlement amount,
The vertical axis shows the calculated value (estimated value (cm) of the differential settlement amount) obtained by the program for calculating the design strength of the ground according to the present invention.

Based on the test results by the Swedish sounding method and the level measurement results of existing buildings, the values calculated (estimated values) by the program for calculating the design strength of the ground according to the present invention and the actually measured values were compared. It can be seen from the figure that the estimated value and the measured value are quite close.

Next, a case in which the present invention is specifically implemented will be described.

FIG. 18 is an explanatory diagram of the “N value” of Case 1 of the present invention, and FIG. 19 is an explanatory diagram of the shape of the ground and the actually measured values of the settlement amount in Case 1. The topographical condition of this ground was a plateau, and there was an eight-year-old house. The design ground strength calculated by the design ground strength calculation program of the ground of the present invention is 1.3 t / m ² (from the settlement amount at the point D), and the estimated value S of the settlement amount is S = 12.95c.
m (the amount of settlement at point D), and the measured value of the amount of settlement is 13.2
0 cm. The maximum tilt angle was 16/1000.

FIG. 20 is an explanatory diagram of the “N value” of Case 2 of the present invention, and FIG. 21 is an explanatory diagram of the shape of the ground and the actually measured values of the settlement amount in Case 2. The topographic condition of this ground is flood plain. The design soil strength calculated by the design soil strength calculation program for the ground of the present invention is 1.6 t / m ² (from the bearing capacity at the point A), and the estimated value S of the settlement amount is S = 6.5 cm (the settlement amount at the point A). Quantity), S
= 5.8 cm (the amount of settlement at point C), and the measured value of the amount of settlement was 5.7 cm. The maximum tilt angle was 7/1000.

As can be seen from the above examples, the values calculated by the program for calculating the designed ground strength of the ground according to the present invention are very close to the actually measured values.

The program for calculating the design strength of the ground according to the present invention may be stored in a program area provided in the file unit 7, or may be stored in a floppy disk set in the floppy disk drive FDD6. It can also be executed on another computer via the PC. Instead of the floppy disk as the computer-readable medium, another similar recording medium can be used. Further, the program can be distributed to another computer via a communication line.

The input data (ground condition data, basic dimension data, etc.) other than the "N value" is not stored in a built-in file, but is input means such as a keyboard (KB) when executing the program. Alternatively, the data can be input from a separate recording medium.

[0094]

As described above, according to the present invention,
Before deciding the basic specifications, the bearing capacity can be objectively calculated from the ground survey results. In addition, by recording a program for using the above-described ground design strength calculation system on a computer-readable recording medium, the user can input the "N value" collected at the site to the computer to design the ground. It is possible to know the bearing capacity and determine the optimum basic specifications easily, quickly and accurately.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the principle of a method for calculating a designed ground strength of a ground according to the present invention.

FIG. 2 is a block diagram illustrating an example of a system configuration of a computer that executes a ground design strength calculation program for ground according to the present invention.

FIG. 3 is a data input screen displayed on a display unit when a ground design strength calculation program according to the present invention is started.

FIG. 4 is an explanatory diagram of an “N value” input screen.

FIG. 5 is a flowchart showing an entire flow of a ground design strength calculation program for ground according to the present invention.

FIG. 6 is a flowchart illustrating details of a procedure for examining a support strength according to the present invention.

FIG. 7 is a flowchart illustrating details of a procedure for examining a settlement amount according to the present invention.

FIG. 8 is a flowchart illustrating details of a procedure for determining an allowable stress degree fe2 in FIG. 5;

FIG. 9 is an explanatory diagram of an example of an “N value” table used in the present invention.

FIG. 10 is an explanatory diagram of a use mode of a result calculated by a ground design strength calculation program for ground according to the present invention.

FIG. 11 is an explanatory diagram of a rectangular division method when calculating the underground stress level.

FIG. 12 is an explanatory diagram of a comparison of a settlement amount due to a change in a basic shape.

FIG. 13 is an explanatory diagram of a method for examining the support force.

FIG. 14 is an explanatory diagram of a method for studying the settlement amount.

FIG. 15 is an explanatory diagram of a method for examining the degree of bearing capacity and the amount of settlement based on the presence or absence of groundwork reinforcement.

FIG. 16 is an explanatory diagram of a calculation example of a support strength and a settlement amount depending on whether or not the groundwork is reinforced.

FIG. 17 is an explanatory diagram of a comparison result between a calculated value by a ground design strength calculation program for ground and an actually measured value according to the present invention.

FIG. 18 is an explanatory diagram of “N value” in case 1 of the present invention.

FIG. 19 is an explanatory diagram of a shape of a building and an actually measured value of a settlement amount in Case 1;

FIG. 20 is an explanatory diagram of “N value” in case 2 of the present invention.

FIG. 21 is an explanatory diagram of a shape of a building and an actually measured value of a settlement amount in Case 2;

FIG. 22 is an explanatory diagram of a conventional base selection method.

[Explanation of symbols]

Reference Signs List 1 Central processing unit (CPU) 2 Read-only memory (ROM) storing basic control program of computer 3 Write / read memory (RAM) 4 CRT or LCD, other display unit (DPL) 5 Input unit 5a Keyboard (KB) 5b Pointing device such as mouse (POIN
T) 6 Floppy disk drive (FDD) 7 File unit suitable for hard disk 7a Ground condition data file 7b Basic dimension data file 7c "N value" data file 7d Bearing data file 7e Sinking amount data file 7f Ground strength data file.

Claims (2)

(57) [Claims] 1. A ground condition data file for storing soil conditions of a ground, a basic dimension data file for storing general-purpose basic dimensions, and an "N value" for each of a plurality of depths below the foundation collected in a Swedish sounding test. An "N-value" data file, a bearing strength data file for storing ground bearing strength, a settlement data file for storing ground subsidence, a ground strength data file for storing designed ground strength data for the ground, Based on the data stored in the ground condition data file, the basic dimension data file, and the "N value" data file , a predetermined size
Repeat the addition of the load to make it larger than the preset bearing capacity.
The load of the specified size added from the load when
The load obtained by subtracting the weight from the above
The data is stored in the data file of the holding strength, and a load of a predetermined magnitude is applied at a plurality of depths below the foundation of the ground.
Calculation is repeated until the amount of settlement at that time is set in advance.
From the load when the amount exceeds the specified size
The load obtained by subtracting the load is used as the allowable stress
Stored in the lower amount data file, and comparing the allowable bearing force data and the allowable stress data stored in the bearing force data file and the sinking amount data file, the smaller one is designated as the design ground strength data of the ground. And a calculating means for storing the ground strength data file in the ground strength data file. A step of storing soil conditions of the ground in a ground condition data file; a step of storing general-purpose foundation dimensions in a foundation dimension data file; Is stored in an “N value” data file; and a predetermined value is set for each of a plurality of depths under the ground based on the ground condition data file, the basic dimension data file, and each data stored in the “N value” data file. Of the size
Repeat the addition of the load to make it larger than the preset bearing capacity.
The load of the specified size added from the load when
The load obtained by subtracting the weight from the above
Storing the data in a holding strength data file; and applying a load of a predetermined magnitude to each of a plurality of depths under the ground.
Calculation is repeated until the amount of settlement at that time is set in advance.
From the load when the amount exceeds the specified size
The load obtained by subtracting the load is used as the allowable stress
Storing the lower bearing data file and the allowable bearing data and the allowable stress data stored in the bearing data file and the sinking data file; and Design ground strength
A computer-readable medium storing a program for causing a computer to execute a method for calculating a design ground strength of a ground, comprising: storing the data as the data in the ground strength data file.