JP7400383B2 - Ground hardness estimation system and ground hardness estimation method - Google Patents

Description

The present invention relates to a ground hardness estimation system and a ground hardness estimation method for estimating the hardness of the ground.

A support layer determination method for determining whether a pile hole has reached the support layer of a pile has been studied (see, for example, Patent Document 1). In this supporting layer determination method, the control unit of the drilling management system outputs a histogram and a depth-N value graph of judgment criterion information in correspondence with the depth of each graph, and is added to the depth-elapsed time graph, and the integrated current value and vertical and horizontal vibration characteristic values associated with the drilling depth are added to each graph and displayed.

By the way, the N value used in Patent Document 1 has different hardness depending on the soil quality.
FIGS. 8(a) and 8(b) show the relationship between the N value and the hardness of the ground for sand and clay, respectively. For example, even if the ground has an N value of "10", if it is sand, it will be determined to be "loose to medium hardness", and if it is clay, it will be determined to be "hard".

Therefore, shear wave velocity is sometimes used to uniformly evaluate the hardness of the ground regardless of soil quality. Since it is difficult to measure shear wave velocity, a formula for calculating shear wave velocity using the N value and soil quality is known (for example, see Non-Patent Document 1). In this document, the shear wave velocity (hereinafter referred to as the "converted shear wave velocity") is calculated by substituting the age coefficient and soil coefficient according to the depth, N value, and soil classification into the calculation formula. calculate.

Japanese Patent Application Publication No. 2018-112011

Yutaka Ota and Noritoshi Goto: "Experimental formula for estimating transverse wave velocity and its physical background", Physical Exploration, Vol. 31, No. 1, February 1978, pp. 8-16

However, in order to obtain the N value and soil classification used to calculate the converted shear wave velocity, it is necessary to conduct a boring survey. Because this boring survey is time-consuming, it has been difficult to efficiently determine shear wave velocities at various locations.

A ground hardness estimation system that solves the above problems includes a measurement information storage unit that records a plurality of measured values that can be obtained when drilling a hole in the ground, and a hardness index value that indicates the hardness of the ground. A ground investigation information storage unit, a multivariate analysis formula storage unit that stores a multivariate analysis formula with the measured value as an explanatory variable and the hardness index value as an objective variable, and a control unit. A system for estimating an index value, wherein the control unit stores each measurement value recorded in the measurement information storage unit and the hardness index value recorded in the ground investigation information storage unit based on an explanatory variable and a purpose. When a multivariate analysis formula is calculated by performing multivariate analysis using variables and recorded in the multivariate analysis formula storage unit, and measurement values obtained when drilling a hole to be evaluated are obtained, these measurement values and Using the multivariate analysis formula, a hardness index value of the ground in which the hole to be evaluated is excavated is estimated.

According to the present invention, the hardness of the ground can be efficiently evaluated.

FIG. 1 is a schematic front view of a drilling device that excavates a pile hole in an embodiment. FIG. 1 is a configuration diagram showing the configuration of a ground hardness estimation system that estimates the hardness of the ground in an embodiment. FIG. 2 is an explanatory diagram of the hardware configuration of the embodiment. It is a figure explaining the data structure of the data storage part in embodiment, Comprising: (a) is a ground investigation data storage part, (b) is an excavation measurement data storage part. A flowchart illustrating a processing procedure for estimating the hardness of the ground in the embodiment. 5 is a flowchart illustrating the processing procedure of multiple regression equation calculation processing in the embodiment. It is a figure comparing the value estimated using the multiple regression formula calculated in the embodiment and the shear rate value calculated by a boring survey at a nearby position, (a) is the first location, (b) is (a ) is different from the second location. It is an explanatory diagram for evaluating the hardness of the ground in three stages in a modified example, in which (a) shows the relationship between the N value and the hardness index value in the case of sand, and (b) shows the relationship between the N value and the hardness index value in the case of clay. shows the relationship with the index value. FIG. 7 is an explanatory diagram illustrating data association when evaluating hardness in three stages in a modified example.

An embodiment of a ground hardness estimation system and a ground hardness estimation method will be described below with reference to FIGS. 1 to 7. In this embodiment, the hardness of the ground where a pile hole for installing a building pile is to be excavated is estimated. Here, the ground whose hardness is estimated includes bedrock.

FIG. 1 shows an excavator 10 as an excavator that excavates a pile hole h0. The excavator 10 includes a base machine 11, a mast 14, and an auger machine 16. The base machine 11 includes a lower traveling body including a crawler 12 and an upper revolving body including an operation chamber 13.

The mast 14 is installed upright on the base machine 11. Inside the mast 14, wires for depth and speed meter measurements are provided. An auger machine 16 is attached to the mast 14 so as to be movable up and down. The auger machine 16 includes a drive motor housed in a box and a drilling rod 17 that is rotationally driven by the drive motor. A drilling head 18 is attached to the tip (lower end) of the drilling rod 17. The excavation head 18 has a excavation blade formed at the tip of a pair (two) of swinging excavation arms. Note that the elevation of the excavation head 18 is controlled by an operator in the operation room 13.

Further, an excavation water supply device (not shown) that supplies excavation water to the excavation head 18 is connected to the excavator 10 . The amount of this excavation water is adjusted by the operator in the operation room 13 depending on the excavation situation.

As shown in FIG. 2, each measuring device (21 to 24) that measures the excavation state and excavation conditions of the excavator 10 is connected to a ground hardness estimation system 30. In this embodiment, it is connected to a drilling depth measuring device 21, a flow rate measuring device 22, a current measuring device 23, and a vibration measuring device 24. Each measuring device (21 to 24) constantly performs measurements and sends the measured values to the ground hardness estimation system 30.

The drilling depth measuring device 21 measures the amount of wire fed out within the mast 14, and measures the drilling depth (depth) according to the position of the drilling head 18. In this case, the drilling depth measuring device 21 measures the drilling depth in relation to time.

The flow meter 22 measures the injection flow rate (water injection amount) of excavation water supplied from the excavation water supply device. In this case, the flow meter 22 measures the amount of water injected in relation to time.
The current measuring device 23 measures the load current of the drive motor of the auger machine 16. In this case, the current measuring device 23 measures the current value in relation to time.

The vibration measuring device 24 measures vibrations at the installation location. In this embodiment, the vibration measuring device 24 is attached to the mast 14 and measures the vibration characteristics of the base machine 11 in three directions: the front-rear direction, the left-right direction, and the up-down direction. In this case, the vibration measuring device 24 measures vibration characteristics in relation to time. Note that the vibration measuring device 24 may be attached to a location other than the mast 14, such as the operation room 13.

(Hardware configuration)
The hardware configuration of the information processing device H10 that constitutes the ground hardness estimation system 30 will be explained using FIG. 3. The information processing device H10 includes a communication device H11, an input device H12, a display device H13, a storage unit H14, and a processor H15. Note that this hardware configuration is just an example, and it can also be implemented using other hardware.

The communication device H11 is an interface that establishes a communication path with other devices and executes data transmission and reception, and is, for example, a network interface card, a wireless interface, or the like.

The input device H12 is a device that accepts input from a worker or the like who estimates the ground hardness, and is, for example, a mouse, a keyboard, or the like. The display device H13 is a display or the like that displays various information.

The storage unit H14 is a storage device that stores data and various programs for executing various functions of the ground hardness estimation system 30. Examples of the storage unit H14 include ROM, RAM, hard disk, and the like.

The processor H15 controls each process in the ground hardness estimation system 30 using programs and data stored in the storage unit H14. Examples of the processor H15 include a CPU, an MPU, and the like. This processor H15 loads a program stored in a ROM or the like into a RAM and executes various processes for estimating the ground hardness.

The processor H15 is not limited to performing software processing for all processes that it executes. For example, the processor H15 may include a dedicated hardware circuit (for example, an application-specific integrated circuit: ASIC) that performs hardware processing for at least part of the processing that it executes. That is, the processor H15 includes (1) one or more processors that operate according to a computer program (software), (2) one or more dedicated hardware circuits that execute at least some of various processes, or ( 3) It can be configured as a circuit including a combination thereof. A processor includes a CPU and memory, such as RAM and ROM, where the memory stores program codes or instructions configured to cause the CPU to perform processing. Memory or computer-readable media includes any available media that can be accessed by a general purpose or special purpose computer.

(Soil hardness estimation system 30)
The ground hardness estimation system 30 in FIG. 2 is a computer system that estimates a hardness index value indicating the hardness of the ground from each measured value during excavation. The ground hardness estimation system 30 includes a control section 31, a ground investigation data storage section 32 as a ground investigation information storage section, an excavation measurement data storage section 33 as a measurement information storage section, and a multiple regression equation as a multivariate analysis equation storage section. A storage unit 34 is provided.

The control unit 31 includes a control means (CPU, RAM, ROM, etc.), and performs processes (processes such as a measurement value management stage, a calculation stage, and an estimation stage) to be described later. For this purpose, the control unit 31 functions as a measured value management unit 311, a calculation unit 312, and an estimation unit 313 by executing the ground hardness estimation program stored in the memory.

The measured value management unit 311 records the geological survey results obtained through the boring survey in the geological survey data storage unit 32.

Further, the measured value management unit 311 stores the measured values obtained from each measuring device (21 to 24) at each time in the memory, and records the measured values at each depth in the excavation measurement data storage unit 33. Specifically, the measured value management unit 311 acquires the drilling depth, water injection amount, current value, and vibration characteristics in the time period during which drilling was actually performed (drilling time period). In hard geological formations, the excavation head 18 may be pulled up once just before digging. For this reason, the actual drilling depth of the drilling head 18 does not necessarily increase monotonically as time elapses. Therefore, the measured value management unit 311 deletes the periods during which the drilling head 18 is withdrawn or stopped from the total working time, and specifies the measured value during the drilling time period that is actually used for drilling. The measured value management unit 311 associates the measured values in the specified drilling time period to determine the depth (start depth, end depth), drilling speed, water injection amount, integrated current value, and vibration characteristics in association with the depth (start depth, end depth). Identify.

Furthermore, the measurement value management unit 311 specifies the magnitude of vibration (amplitude value) for each analysis frequency by performing frequency analysis on the vibration characteristics in the three directions measured by the vibration measuring device 24. In this embodiment, frequencies in 20 intervals of 1/3 octave band analysis frequencies (1 Hz to 80 Hz) are used as analysis frequencies. This frequency is 1Hz, 1.25Hz, 1.6Hz, 2Hz, 2.5Hz, 3.15Hz, 4Hz, 5Hz, 6.3Hz, 8Hz, 10Hz, 12.5Hz, 16Hz, 20Hz, 25Hz, 31.5Hz, 40Hz, 50Hz, 63Hz, 80Hz It is.

The calculation unit 312 performs multivariate analysis to calculate a multiple regression equation. Specifically, the calculation unit 312 uses the data acquired from the ground investigation data storage unit 32 to calculate an objective variable indicating the hardness of the ground.

Here, since the converted shear wave velocity is used as the objective variable, the calculation unit 312 stores an equation for calculating the converted shear wave velocity. As the formula for calculating this converted shear wave velocity, for example, the formula proposed by Goto Ota, which is calculated using the N value, depth, age coefficient, and soil quality coefficient, is used. This proposed formula is shown by formula (1) in FIG. The age coefficient is a coefficient indicating the age of geology, and for example, "1.0" is used for new geology, and "1.306" is used for old geology. Moreover, the soil quality coefficient is a coefficient associated with soil quality classification, and for example, "1.0" is used for clay, and "1.085" is used for sand. In this embodiment, the calculation unit 312 stores a soil quality correspondence table of soil coefficients corresponding to soil quality classifications.

Further, the calculation unit 312 calculates a multiple regression equation using a plurality of measured values obtained during excavation as explanatory variables, and stores the objective variable indicating the hardness of the ground in the multiple regression equation storage unit 34. In this embodiment, the calculation unit 312 stores a multiple regression model formula. This model formula is Equation (2) shown in FIG. 5, where [objective variable y]=regression coefficient a1×[explanatory variable X1]+regression coefficient a2×[explanatory variable explanatory variable Xm] + [intercept b]. Furthermore, the calculation unit 312 holds data regarding the reference p value of the regression coefficient in order to delete explanatory variables that have a small influence. In this embodiment, "0.05" is used as the reference p value.
The estimating unit 313 estimates the hardness of the ground of the excavated pile hole by substituting the measured value obtained when the pile hole is newly excavated into the multiple regression equation stored in the multiple regression equation storage unit 34.

As shown in FIG. 4(a), the ground investigation data storage unit 32 records ground investigation data obtained from boring investigation results. In the ground survey data, the N value, soil type classification, age coefficient, and converted shear wave velocity are recorded in association with the site identifier, survey position coordinates, and depth.

In the site identifier data area, data related to an identifier for specifying the site where the boring survey was conducted is recorded.
In the survey position coordinate data area, data regarding the coordinates of the position where the boring survey was conducted at this site is recorded.

In the depth data area, data regarding the N value and the depth for specifying the soil quality at this boring survey position are recorded. In this embodiment, the depth is recorded in units of, for example, 0.1 m, and the depth range (end depth and start depth) is recorded.

Data regarding the N value measured at this depth is recorded in the N value data area.
In the soil classification data area, data regarding an identifier for specifying the soil classification at this depth is recorded. The soil quality coefficient can be specified using this soil quality classification and the soil quality correspondence table.

The age coefficient data area records data regarding the age coefficient of the ground at this depth.
In the converted shear wave velocity data area, data regarding the converted shear wave velocity at this depth is recorded.

As shown in FIG. 4B, the excavation measurement data storage unit 33 records excavation measurement values in association with site identifiers, pile numbers, pile coordinates, and depths. The excavation measurement value is a measurement value that can be obtained when a pile hole is excavated. In this embodiment, values related to an integrated current value, excavation speed, injection amount, and vibration are used as excavation measurement values. Furthermore, the end depth of the depth is used as the excavation measurement value.

In the site identifier data area, data related to an identifier for specifying the site where this pile hole was excavated is recorded.
In the pile number data area and the pile coordinate data area, a number for identifying an excavated pile and data regarding the position coordinates of the pile are recorded. Using these pile coordinates and the survey position coordinates in the ground survey data storage section 32, the excavation measurement data can be associated with the ground survey data obtained by performing a boring survey at the closest location.

In the depth data area, data regarding the depth of the measured value obtained in this pile hole is recorded. In this embodiment, the depth is recorded in units of, for example, 0.1 m, and the depth range (end depth and start depth) is recorded.

The integrated current value data area, excavation speed data area, and water injection amount data area each contain an integrated current value (integral current value) calculated from the measured current value, the speed of the excavation head 18 when excavating (excavation speed), Data regarding the injection amount (water injection amount) that supplied drilling water is recorded.

In the vibration data area, data regarding the direction of vibration (three directions: front and back, left and right, and up and down) and the amplitude at each center frequency of 20 amplitude sections are recorded.
The multiple regression equation storage unit 34 records data related to the multiple regression equation. Here, identifiers for specifying the target variable, explanatory variables of the target variable, and coefficients (regression coefficients) of each explanatory variable are stored.

(Soil hardness estimation method)
Next, a method for estimating the ground hardness using the above-described ground hardness estimation system 30 will be explained using FIGS. 5 to 7.

First, the control unit 31 of the ground hardness estimation system 30 executes a process of registering boring survey results (step S1-1). Specifically, the measured value management unit 311 of the control unit 31 acquires a site identifier for identifying the site and the coordinates of the survey position where the boring survey was conducted at the site via the input device H12, and stores the information in the ground survey data storage unit 32. to be recorded. Furthermore, the measured value management unit 311 acquires the N value, soil classification, and age coefficient according to the depth in this boring survey, and records them in the ground survey data storage unit 32.

Next, the control unit 31 of the ground hardness estimation system 30 executes a calculation process of the converted shear wave velocity (step S1-2). Specifically, the calculation unit 312 of the control unit 31 acquires the N value, soil classification, depth, and age coefficient from the ground investigation data storage unit 32. Further, the calculation unit 312 uses the soil type classification and the soil type correspondence table to identify the soil type coefficient. Furthermore, the calculation unit 312 calculates the converted shear wave velocity Vs' by substituting the N value, depth, age coefficient, and soil quality coefficient into the converted shear wave velocity calculation formula for each depth, and stores the ground survey data. 32.

Next, the control unit 31 of the ground hardness estimation system 30 executes recording processing of excavation measurement data based on the measured values (step S1-3). Specifically, the measured value management unit 311 of the control unit 31 acquires the measured values measured by each measuring device (21 to 24) when a pile hole is excavated, and stores them in the memory. In this case, the measurement value management unit 311 specifies the time period in which drilling actually progressed (drilling time period) in the drilling depth for each hour, and determines the drilling depth, water injection amount, current value, and vibration in this time period. Identify characteristics. Then, the measured value management unit 311 specifies the water injection amount according to the specified drilling depth (depth), and records the water injection amount in the excavation measurement data storage unit 33 in association with the depth. Furthermore, the measured value management unit 311 calculates a drilling speed and an integrated current value based on the specified drilling depth in association with the drilling depth, and records them in the drilling measurement data storage unit 33. Furthermore, the measurement value management unit 311 specifies the amplitude value in the vibration direction and analysis frequency by vibration-analyzing the vibration based on the specified drilling depth, and stores the amplitude value in the drilling measurement data storage unit 33 in association with the drilling depth. Record.

Next, the control unit 31 of the ground hardness estimation system 30 executes calculation processing using a multiple regression equation (step S1-4). Specifically, the control unit 31 uses the ground hardness index value (converted shear wave velocity) as an objective variable, and calculates regression coefficients for each explanatory variable. Here, as explanatory variables, among the logarithm value of the integrated current value, end depth, excavation speed, water injection amount, and vibration, explanatory variables whose influence is not small are used. The vibration has frequencies in 20 sections in three directions. Then, the control unit 31 stores the calculated explanatory variables and regression coefficients of the multiple regression equation in the multiple regression equation storage unit. Details of the calculation process of this multiple regression equation will be described later.

Thereafter, the control unit 31 of the ground hardness estimation system 30 executes a process of estimating the ground hardness of the pile hole based on the newly acquired measured value (step S1-5). Specifically, the measured value management unit 311 of the control unit 31 acquires the measured values measured by each measuring device (21 to 24) when a new pile hole is excavated using the excavator 10. Then, as in step S1-3, the measured value management unit 311 determines the water injection amount, drilling speed, integrated current value, vibration direction, and amplitude value at the analysis frequency according to the drilling depth during the actual drilling time. is recorded in the excavation measurement data storage unit 33 in association with the drilling depth (depth).

Next, the estimation unit 313 of the control unit 31 acquires explanatory variables used in the multiple regression equation recorded in the multiple regression equation storage unit 34 from the excavation measurement data storage unit 33. Then, the estimation unit 313 calculates the converted shear wave velocity Vs' by substituting the acquired water injection amount, drilling speed, end depth, integrated current value, vibration direction, and amplitude value of the analysis frequency into the multiple regression equation. . Then, the estimation unit 313 records the estimated converted shear wave velocity Vs′ in the excavation measurement data storage unit 33 and outputs it to the display device H13.

(Calculation method of multiple regression equation)
Next, details of the multiple regression equation calculation process will be described using FIG. 6. In this embodiment, a multiple regression equation is calculated using data obtained when 20 holes were excavated at four different sites.

First, the control unit 31 executes data association processing (step S2-1). Specifically, the measured value management unit 311 of the control unit 31 extracts excavation measurement data and ground survey data of the site whose site identifiers match from the ground survey data storage unit 32 and the excavation measurement data storage unit 33, respectively. . Then, the measurement value management unit 311 associates the excavation measurement data of the pile hole and the ground survey data for each same depth. In addition, when a plurality of borings are performed at the same site, the measured value management unit 311 uses the ground survey data of the boring position where the pile hole position is closest, and associates it with the excavation measurement data.

Next, the control unit 31 executes a relational expression setting process (step S2-2). Specifically, the calculation unit 312 of the control unit 31 uses the converted shear wave velocity Vs' of the associated ground survey data as an objective variable and each measurement value of the excavation measurement data as an explanatory variable in the multiple regression model equation. , set a relational expression in which the explanatory variable is multiplied by the regression coefficient. For example, the relational expression shown in equation (3) in FIG. 6 is set. Here, in this embodiment, a logarithmic value is used for the integrated current value.

Then, the control unit 31 executes a process of identifying a regression coefficient that can best explain the data (step S2-3). Specifically, the calculation unit 312 of the control unit 31 calculates each regression coefficient of each explanatory variable by the least squares method or the like.

Next, the control unit 31 executes a process of deleting explanatory variables with little influence (step S2-4). Specifically, the calculation unit 312 of the control unit 31 identifies a multiple regression equation for calculating ground hardness by deleting explanatory variables whose regression coefficients have p-values equal to or less than the stored reference p-value. , is stored in the multiple regression equation storage unit 34. Here, the identified multiple regression equation is shown as equation (4) in FIG.
Note that the selection of explanatory variables is not limited to the method using the p value shown here, and any method may be used as long as it is possible to delete explanatory variables that have little influence. For example, the selection may be based on AIC (Akaike Information Criterion).

In this embodiment, the logarithm of the integrated current value, the end depth, and the water injection amount are used as explanatory variables of the specified multiple regression equation. Further, as explanatory variables, vibrations with center frequencies of 3.15Hz, 8Hz, 12.5Hz, 31.5Hz, 40Hz, 50Hz, 63Hz, and 80Hz are used for vibrations in the left-right direction. Furthermore, as explanatory variables, 1.6Hz, 2.5Hz, 8Hz, 10Hz, 12.5Hz, 20Hz, 25Hz, 31.5Hz, 40Hz, 50Hz, 63Hz, and 80Hz are used for vibration in the vertical direction. Furthermore, for the back and forth vibration, 1Hz, 2Hz, 2.5Hz, 4Hz, 8Hz, 12.5Hz, 20Hz, and 50Hz are used.

(verification)
FIGS. 7(a) and 7(b) show a comparison between the shear wave velocity Vs estimated using the multiple regression equation and Vs' determined from the ground investigation at the site. FIGS. 7(a) and 7(b) show the case where verification was performed at two different locations at the same site. These are calculated by calculating the converted shear wave velocity Vs' from boring surveys conducted at different locations, and by calculating the estimated shear wave velocity Vs using data measured during excavation of pile holes in the vicinity of each boring survey location. ing.

From Figures 7(a) and (b), the shear wave velocity Vs estimated using the measured value data during pile hole excavation and the multiple regression equation is the same as the converted shear wave velocity Vs' calculated from the nearby boring survey. It can be seen that the values are approximate.

According to this embodiment, the following effects can be obtained.
(1) In the present embodiment, the control unit 31 of the ground hardness estimation system 30 executes the process of estimating the ground hardness of the pile hole based on the newly acquired measured value (step S1-5). Thereby, the hardness of the ground in the pile hole can be specified from the measured value when the pile hole is excavated, so the hardness of the ground at the location where the hole is formed can be efficiently evaluated.

(2) In the present embodiment, the control unit 31 of the ground hardness estimation system 30 associates the ground survey data of the location closest to the hole at the same site with the excavation measurement data of the hole. As a result, it is possible to generate a relational expression that evaluates the hardness that approximates the hardness in the excavated hole, so even if the N value or soil classification of the excavated pile hole is unknown, the hardness can be estimated.

(3) In the present embodiment, the control unit 31 of the ground hardness estimation system 30 calculates the converted shear wave velocity Vs' as the ground hardness index value. This makes it possible to uniformly evaluate the hardness of the ground regardless of soil classification.

This embodiment can be modified and implemented as follows. This embodiment and the following modified examples can be implemented in combination with each other within a technically consistent range.
- In the above embodiment, the control unit 31 of the ground hardness estimation system 30 calculates a multiple regression equation by correlating excavation measurement data and ground survey data at four different sites. The number of sites from which data for calculating the multiple regression equation is acquired is not limited to four. For example, field data in a predetermined area (for each area such as Kanto or Kansai) where the deposition environment is common may be used. Alternatively, a multiple regression equation may be calculated for each site.

- In the above embodiment, the control unit 31 of the ground hardness estimation system 30 used the integral current value, end depth, excavation speed, water injection amount, and vibration as explanatory variables for calculating the ground hardness index value. The explanatory variables are not limited to these, and may be any value that can be measured when forming a hole or a value that can be calculated therefrom. For example, starting depth, instantaneous current value, excavation acceleration, etc. may be used. Furthermore, although a logarithmic value is used as the integral current value in the above multiple regression equation, the integral current value may be used as it is in the equation.
- In the above embodiment, when vibration is used as an explanatory variable, the amplitude value at the frequency of 1/3 octave band analysis is used. Measured values related to vibration are not limited to these, and, for example, characteristic values obtained by other analysis methods (Fourier analysis) may be used.

- In the above embodiment, the control unit 31 of the ground hardness estimation system 30 estimated the converted shear wave velocity Vs' as the ground hardness index value. The estimated ground hardness index value is not limited to this.

For example, the tip bearing capacity may be used as the ground hardness index value. This tip bearing capacity can be determined, for example, by Yoshinobu Kitani and Tomoharu Hirose, "Proposal of Bearing Capacity Coefficient of Embedded Piles," Abstracts of Academic Lectures at the Architectural Institute of Japan, Structural I, September 2018, pp. It can be calculated using the following formulas (5) and (6) described in 719-720.
In the case of sand: Tip support strength qp=222×N...(5)
In the case of clay: Tip bearing capacity qp = 268 x N … (6)
In these formulas (5) and (6), "N" is the N value.
For this reason, the control unit 31 stores a formula for calculating the tip bearing capacity degree according to the soil type classification. Furthermore, the tip bearing capacity degree is recorded in the ground investigation data storage unit 32 instead of the converted shear wave velocity Vs'.

After the boring survey result registration process (step S1-1), the control unit 31 calculates the tip support strength as the hardness index value instead of the converted shear wave velocity Vs'. Here, the control unit 31 specifies the tip bearing capacity by substituting the N value of the ground survey data storage unit 32 into the formula for calculating the tip bearing capacity according to the soil classification.
Then, in the data association process (step S2-1), the control unit 31 associates the specified tip bearing capacity with the excavation measurement data instead of the converted shear wave velocity Vs' of the ground survey data. Then, the control unit 31 calculates a multiple regression equation using the tip support force as an objective variable.

Furthermore, three levels of index values ("1", "2", and "3") may be used as the ground hardness index value.
As shown in FIG. 8(a), in the case of sand, the N values of "0 or more and less than 10", "10 or more and less than 30", and "30 or more" are "1", "2", and "3", respectively. ” hardness and setting. Furthermore, as shown in FIG. 8(b), in the case of clay, the N values of "0 or more and less than 4", "4 or more and less than 8", and "8 or more" are respectively "1", "2", and Set the firmness to "3".

Furthermore, the control unit 31 of the ground hardness estimation system 30 stores corresponding data for specifying three levels of ground hardness index values from the N value and the soil classification. Furthermore, the ground investigation data storage unit 32 records a hardness index value instead of the converted shear wave velocity Vs'.

Also in this case, the control unit 31 calculates the stiffness index value instead of the converted shear wave velocity Vs'. Here, the control unit 31 specifies the hardness index value using the N value and soil classification in the ground investigation data storage unit 32, and the corresponding data.
Then, the control unit 31 executes data association processing (step S2-1).
Here, as shown in FIG. 9, hardness is associated with the excavation measurement data instead of the converted shear wave velocity Vs' of the ground survey data. Then, the control unit 31 calculates a multiple regression equation using the hardness as an objective variable.

Furthermore, the method of multivariate analysis is not limited to multiple regression analysis that calculates multiple regression equations. For example, instead of regression analysis, logistics regression analysis may be used. Specifically, when a multivariate analysis formula is generated by setting "1" when the hardness is "2" or more and "0" when it is less than "2", the following formula (7) is obtained. .
y ₂₃ = 1/{1+exp[-(a1×x1+a2×x2+…+am×xm+b)]}…(7)
Here, y ₂₃ is an objective variable and indicates the probability that the hardness will be "2" or more (0≦y ₂₃ ≦1).
And x1, x2, ..., xm are explanatory variables, and each measured value is used. Furthermore, a1, a2, ..., am are regression coefficients corresponding to each explanatory variable, and b is a regression coefficient.

Next, when a regression equation is generated by setting "1" when the hardness is "3" or more and "0" when the hardness is less than "3", the following equation (5) is obtained.
y ₃ = 1/{1+exp[-(α1×x1+α2×x2+…+αm×xm+β)]}…(8)
Here, y ₃ is an objective variable and indicates the probability that the hardness will be "3" or more (0≦y ₃ ≦1).
And x1, x2, ..., xm are explanatory variables, and each measured value is used. Further, α1, α2, αm are regression coefficients corresponding to each explanatory variable, and β is a regression coefficient.

Here, using equation (7), the probability that the hardness does not exceed "2", that is, the probability that the hardness becomes "1", which is less than "2", is calculated using equation (9). Further, using Equations (8) and (9), the probability that the hardness will be "2" (the probability that it will be greater than or equal to "2" and less than "3") is calculated using Equation (10).

y ₁ = 1 - y ₂₃ ...(9)
_y2 =1- _y3 - _y1 ...(10)
Based on the regression coefficients a, b, α, and β obtained above, regression equations (8) to (10), and the measured values during excavation of the newly drilled hole to be evaluated, the probability that the hardness will be 1 to 3 ( y ₁ , y ₂ , y ₃ ) can be calculated.

Specifically, the estimated value of hardness is calculated as the average weighted probability using the following formula.
[Estimated hardness] = y ₁ × 1 + y ₂ × 2 + y ₃ × 3 … (11)
Furthermore, instead of the estimated value of hardness calculated by this formula (11), it is possible to use the maximum value (maximum probability) of y ₁ , y ₂ , y ₃ as the estimated value of hardness. can.

- In the above embodiment, the multivariate analytical formula for estimating the ground hardness was calculated using excavation measurement value data when forming a pile hole. The excavation measurement value used to calculate the multivariate analytical formula is not limited to the value when forming a pile hole, and excavation measurement value data when forming another hole may be used.

Next, technical ideas that can be understood from the above embodiment and other examples will be additionally described below.
(a) The ground hardness estimation system according to any one of claims 1 to 3, wherein the control unit calculates the multivariate analytical formula for each ground according to a sedimentation environment.

h0...Pile hole, Vs'...Converted shear wave velocity, 10...Excavator, 11...Base machine, 12...Crawler, 13...Operation room, 14...Mast, 16...Auger machine, 17...Drilling rod, 18...Drilling head , 20... Ground hardness estimation system, 21... Drilling depth measuring device, 22... Flow rate measuring device, 23... Current measuring device, 24... Vibration measuring device, 30... Ground hardness estimation system, 31... Control unit, 32... Ground investigation data storage section as a ground investigation information storage section, 33... Excavation measurement data storage section as a measurement information storage section, 34... Multiple regression equation storage section as a multivariate analysis equation storage section, 311... Measured value management section, 312...Calculation unit, 313...Estimation unit.

Claims (3)

a measurement information storage unit that records a plurality of measurement values that can be obtained when drilling a hole in the ground;
a ground investigation information storage unit that records a hardness index value according to the shear wave velocity of the ground;
a multivariate analysis formula storage unit that stores a multivariate analysis formula with the measured value as an explanatory variable and the hardness index value as an objective variable;
A system for estimating the hardness index value, comprising a control unit,
The control unit includes:
A multivariate analysis formula is created by performing multivariate analysis using each measurement value recorded in the measurement information storage unit and the hardness index value recorded in the ground investigation information storage unit as explanatory variables and objective variables. Calculate and record in the multivariate analysis formula storage unit,
When measured values are obtained when a hole to be evaluated is excavated, the hardness index value of the ground in which the hole to be evaluated is excavated is estimated by using these measured values and the multivariate analysis formula. A ground hardness estimation system featuring: The ground solidification system according to claim 1, wherein the control unit uses at least a plurality of logarithmic values of an integrated current value, depth, excavation speed, water injection amount, and vibrations at predetermined frequencies in three directions as the explanatory variables. estimation system. a measurement information storage unit that records a plurality of measurement values that can be obtained when drilling a hole in the ground;
a ground investigation information storage unit that records a hardness index value according to the shear wave velocity of the ground;
a multivariate analysis formula storage unit that stores a multivariate analysis formula with the measured value as an explanatory variable and the hardness index value as an objective variable;
A method for estimating the hardness index value, the method comprising:
The control unit includes:
A multivariate analysis formula is created by performing multivariate analysis using each measurement value recorded in the measurement information storage unit and the hardness index value recorded in the ground investigation information storage unit as explanatory variables and objective variables. Calculate and record in the multivariate analysis formula storage unit,
When measured values are obtained when a hole to be evaluated is excavated, the hardness index value of the ground in which the hole to be evaluated is excavated is estimated by using these measured values and the multivariate analysis formula. A ground hardness estimation method featuring: