Ground evaluation system and ground evaluation method

Abstract

To quickly obtain information for assessment of the integrity of structures after an earthquake occurs.SOLUTION: A ground evaluation system 1 includes a sensor 21 that obtains evaluation target data D1 for evaluating the soundness of the ground, which is at least one of the acceleration and the velocity acting on an evaluation point 81 along a vertical reference line 83 based on a ground surface 82 on the ground 8, and an information processing device 4 that uses the evaluation target data D1 to obtain evaluation value data D2 for evaluating the ground 8. The information processing device 4 has an evaluation value calculation unit 41 that obtains the evaluation value data D2 using at least one of the horizontal components of the acceleration and the velocity included in the evaluation target data D1.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a ground evaluation system and a ground evaluation method. [Background technology]

[0002] After an earthquake, the ground conditions are evaluated, and the structural integrity is determined based on the evaluation results. Based on the integrity assessment, it is decided whether repairs or countermeasures are necessary for the structures and the ground. This process first involves acquiring ground surface acceleration data, which is the data to be evaluated. Next, several evaluation values ​​are obtained through numerical calculations using the data to be evaluated. Finally, the necessity of repairs or countermeasures is determined using these evaluation values.

[0003] Non-patent document 1 discloses an energy-based method for evaluating liquefaction. Whether or not liquefaction occurs is one of the indicators for determining the soundness of a structure. This evaluation method focuses on cumulative energy loss as a physical quantity that governs liquefaction more directly than stress. The determination of liquefaction is made by comparing cumulative energy loss with seismic uplift energy. According to the method disclosed in this document, the generated strain and settlement can be obtained by simple calculations. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] Tsuyoshi Kunisho, Simplified calculation of generated strain and settlement using an energy-based liquefaction evaluation method and its application to past cases, Japanese Geotechnical Society, December 31, 2020, Vol. 15, No. 4, pp. 683-695. [Non-Patent Document 2] The Japanese Geotechnical Society, "Geotechnical Engineering: Basic Theory Series 2 - Dynamic Analysis of Soil - From Basic Theory to Applications," Japan, The Japanese Geotechnical Society, February 28, 2007. [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] It is crucial to confirm the structural integrity immediately after an earthquake. In other words, it is desirable to obtain information for structural integrity assessments conducted after an earthquake as quickly as possible.

[0006] Methods such as the effective stress analysis disclosed in Non-Patent Document 2 yield relatively accurate results. However, they have drawbacks, including the complexity of the calculation steps, the need for specialized knowledge and skills in handling the analysis software used for calculations, and the high computational load, resulting in long calculation times and high costs. Due to these factors, it is difficult to obtain information for assessing structural integrity quickly after an earthquake, making these methods unsuitable for immediate assessment.

[0007] Therefore, the present invention provides a ground evaluation system and a ground evaluation method that can obtain information for evaluating structural integrity after an earthquake in a short amount of time. [Means for solving the problem]

[0008] One embodiment of the present invention is a ground evaluation system for evaluating the ground on which a structure is installed, comprising: a first sensor that obtains first evaluation target data for evaluating the soundness of the ground, which is at least one of the acceleration and velocity acting on a first evaluation point set at a first depth along a first vertical reference line with respect to the ground surface in the ground; a second sensor that obtains second evaluation target data, which is at least one of the acceleration and velocity acting on a second evaluation point set at a second depth different from the first depth along a second vertical reference line with respect to the ground surface in the ground; and an information processing unit that obtains an evaluation value for evaluating the ground using the first evaluation target data and the second evaluation target data, wherein the information processing unit has an evaluation value calculation unit that obtains an evaluation value using at least one of the horizontal components of acceleration and velocity included in the first evaluation target data and at least one of the horizontal components of acceleration and velocity included in the second evaluation target data.

[0009] The ground evaluation system directly obtains evaluation target data for each evaluation point by means of the first sensor and the second sensor without relying on calculations. Therefore, the ground evaluation system can obtain the information required for confirming the soundness of the structure in a short time through simple calculations.

[0010] The evaluation value calculation unit of the ground evaluation system described above may correct the evaluation value by using at least one of the vertical components of acceleration and velocity included in the first evaluation target data and at least one of the vertical components of acceleration and velocity included in the second evaluation target data. According to this configuration, the accuracy of the evaluation value can be improved.

[0011] The evaluation value calculation unit of the ground evaluation system described above may obtain the relative value between the first evaluation target data and the second evaluation target data. Also according to this configuration, the information for the soundness evaluation can be obtained in a short time.

[0012] The ground evaluation system described above may further include a third sensor and a fourth sensor that are arranged at different depths along a second vertical reference line that is horizontally separated from the first vertical reference line. Also according to this configuration, the information for the soundness evaluation can be obtained in a short time.

[0013] Another aspect of the present invention is a ground evaluation method for evaluating the ground on which a structure is provided, including: a step of installing a first sensor for obtaining first evaluation target data for evaluating the soundness of the ground, which is at least one of acceleration and velocity acting on a first evaluation point set at a first depth along a first vertical reference line with the ground surface as a reference in the ground; a step of installing a second sensor for obtaining second evaluation target data, which is at least one of acceleration and velocity acting on a second evaluation point set at a second depth different from the first depth along a second vertical reference line with the ground surface as a reference in the ground; and a step of obtaining an evaluation value for evaluating the ground by using the first evaluation target data and the second evaluation target data. The step of obtaining the evaluation value obtains the evaluation value by using at least one of the horizontal components of acceleration and velocity included in the first evaluation target data and at least one of the horizontal components of acceleration and velocity included in the second evaluation target data.

[0014] In the above-described ground evaluation method, the steps of installing the first sensor and installing the second sensor may be carried out in parallel with the construction of the structure.

[0015] In the above-described ground evaluation method, the steps of installing the first sensor and installing the second sensor may be performed after the construction of the structure is completed. [Effects of the Invention]

[0016] According to the present invention, a ground evaluation system and a ground evaluation method are provided that can quickly obtain information for evaluating the structural integrity of ground after an earthquake. [Brief explanation of the drawing]

[0017] [Figure 1] Figure 1 is a schematic diagram showing the configuration of the ground evaluation system according to the embodiment. [Figure 2] Figure 2 shows sensors placed in the ground. [Figure 3] Figure 3(a) shows an example of sensor units being placed on an embankment, which is a structure. Figure 3(b) shows an example of sensor units being placed around the foundation piles of a building, which is a structure. [Figure 4] Figure 4 is a diagram illustrating the computer that constitutes the information processing device of the ground evaluation system shown in Figure 1. [Figure 5] Figure 5 is a functional block diagram showing the configuration of the information processing device included in the ground evaluation system shown in Figure 1. [Figure 6] Figure 6 is a flowchart showing the main steps of the ground evaluation method. [Figure 7] Figure 7 is a schematic diagram showing the ground evaluation system of the comparative example. [Modes for carrying out the invention]

[0018] Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the attached drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant explanations are omitted.

[0019] As shown in Figure 1, the ground evaluation system 1 evaluates the ground 8 on which the structure 9 is installed. Based on the evaluation results of the ground 8, the soundness of the structure 9 can be determined. The soundness of the structure 9 may also be defined from the perspective of whether or not repair work on the structure 9 or the ground 8 is necessary to ensure the safety of the structure 9. For example, when an earthquake acts on the ground 8, various changes occur in the ground 8, such as liquefaction and settlement. Depending on the degree of these changes, the safety of the structure 9 may not be ensured, and repair work on the structure 9 or the ground 8 may be required. The ground evaluation system 1 provides the user 93 with information (judgment result data D4) to determine whether or not this repair work is necessary.

[0020] The ground evaluation system 1 comprises a sensor unit 2, an information collection device 3, and an information processing device 4. The sensor unit 2 is embedded in the ground 8. The sensor unit 2 acquires evaluation target data D1. Furthermore, the sensor unit 2 outputs the acquired evaluation target data D1 to the information collection device 3. The information collection device 3 temporarily stores the evaluation target data D1. The information collection device 3 outputs the evaluation target data D1 to the information processing device 4. The information processing device 4 uses the evaluation target data D1 to provide judgment result data D4 to the user 93. The information processing device 4 is an information processing unit in a broad sense.

[0021] The information gathering device 3 may be omitted if necessary. In this case, the information processing device 4 may substitute for the functions of the information gathering device 3.

[0022] The sensor unit 2 is embedded in the ground 8 beneath the structure 9. An evaluation area 80 is defined in the ground 8. The evaluation area 80 defines the area to be evaluated by the ground evaluation system 1. The evaluation area 80 includes multiple evaluation points 81 (first evaluation point, second evaluation point). The evaluation points 81 define the specific locations where the evaluation target data D1 is acquired in the initial state.

[0023] A sensor 21 (first sensor, second sensor, third sensor, fourth sensor) is placed at each of the multiple evaluation points 81. In other words, the sensor 21 obtains evaluation target data D1 at the evaluation point 81 where it is placed. The evaluation target data D1 is at least one of acceleration data and velocity data. In addition, each data includes at least a horizontal X component. The horizontal X component may be only a component along the first axis (X axis), or it may include two components: a component along the first axis and a component along the second axis (Y axis) perpendicular to the first axis. Furthermore, each data includes a vertical Z component (Z axis). By integrating the vertical Z component of acceleration, the vertical Z displacement of the sensor 21 can be obtained. The vertical Z displacement of the sensor 21 can accurately correct the variables used in the theoretical formula described later.

[0024] When the data to be evaluated D1 is acceleration, sensor 21 is an accelerometer. The accelerometer may be a mechanical accelerometer or an optical accelerometer using optical fibers. The accelerometer may be a biaxial accelerometer capable of acquiring one acceleration component in the horizontal direction X and one acceleration component in the vertical direction Z. Alternatively, the accelerometer may be a triaxial accelerometer capable of acquiring acceleration components in the horizontal direction X, horizontal direction Y, and vertical direction Z.

[0025] If the ground evaluation system 1 is used to evaluate the effect of long-period earthquakes on the ground 8, the sensor 21 may be a velocity meter instead of an accelerometer. Alternatively, the sensor 21 may be a measuring instrument capable of acquiring both acceleration and velocity.

[0026] Sensor 21 acquires the response of evaluation point 81 caused by the seismic waves input to evaluation point 81. In other words, it acquires the acceleration and / or velocity at evaluation point 81. Sensor 21 continuously outputs the acceleration and / or velocity information at evaluation point 81 to the information acquisition device 3.

[0027] As shown in Figure 2, the sensors 21 are installed along three vertical reference lines 83 (first vertical reference line, second vertical reference line) along the vertical direction Z. The spacing between adjacent vertical reference lines 83 may be the same. In the example in Figure 2, three sensors 21 are installed along each vertical reference line 83. Note that the number of sensors 21 installed along one vertical reference line 83 is not limited to three. The ground evaluation system 1 only needs to include at least one vertical reference line 83 and have at least two sensors 21 installed along that vertical reference line 83. The spacing (span) of the sensors 21 may be equal, as shown in Figure 2. The spacing of the sensors 21 in the vertical direction Z may be, for example, 0.5m to 1.0m. By installing the sensors 21 at shorter intervals, more accurate results can be obtained. Note that the spacing of the sensors 21 does not have to be equal. For example, the arrangement of the sensors 21 may be varied in density depending on the distribution of mechanical properties in the evaluation region 80.

[0028] Furthermore, the placement of the sensors 21 may be determined according to the structure 9 installed on the ground 8. Examples of structures 9 include an embankment 91 (see Figure 3(a)) and a building 92 (see Figure 3(b)). If the structure 9 is an embankment 91, multiple sensors 21 may be installed inside the embankment 91 at a position higher than the original ground (ground surface 82). Also, if the structure 9 is a building 92 and the object of soundness evaluation is the foundation pile 921 of the building 92, multiple sensors 21 may be installed along the vertical direction Z in which the foundation pile 921 extends.

[0029] As shown again in Figure 1, the information gathering device 3 is connected to the sensor unit 2. There are no particular restrictions on the connection configuration between the information gathering device 3 and the sensor unit 2. For example, the information gathering device 3 and the sensor unit 2 may be connected by a wired connection. That is, the information gathering device 3 and the sensor unit 2 may be directly connected by a communication cable. Alternatively, the information gathering device 3 and the sensor unit 2 may be connected wirelessly. That is, the information gathering device 3 and the sensor unit 2 may be connected by a wireless communication means such as Wi-Fi. Furthermore, the information gathering device 3 and the sensor unit 2 may be connected by a combination of wired and wireless connections. That is, the end of the communication cable extending from the sensor 21 may be connected to a repeater installed on the ground surface 82, and the information gathering device 3 may be connected from the repeater via a communication network such as the Internet.

[0030] The information acquisition device 3 continuously records the evaluation target data D1 that is continuously transmitted from the sensor unit 2. For example, the information acquisition device 3 may continuously record the evaluation target data D1 by repeatedly overwriting a predetermined memory area. In this case, the information acquisition device 3 can hold the evaluation target data D1 for a predetermined period determined according to the size of the memory area. When the input evaluation target data D1 satisfies a condition, the information acquisition device 3 stops repeatedly overwriting and holds the evaluation target data D1 for a predetermined period based on when the evaluation target data D1 satisfies the condition. The information acquisition device 3 then transmits the evaluation target data D1 for the predetermined period to the information processing device 4. The transmission of the evaluation target data D1 from the information acquisition device 3 to the information processing device 4 may be an active operation of the information acquisition device 3 or a passive operation in accordance with a command transmitted from the information processing device 4.

[0031] The information processing device 4 obtains judgment result data D4 using the evaluation target data D1. The information processing device 4 then presents the judgment result data D4 to the user 93. The information processing device 4 is realized by a computer executing a predetermined program. Figure 4 is a diagram showing an example of the hardware configuration of the computer 400 that constitutes the information processing device 4 of the ground evaluation system 1 according to the embodiment.

[0032] As an example, computer 400 includes, as hardware components, a processor 401, a main memory unit 402, an auxiliary memory unit 403, and a communication control unit 404. Computer 400 may also include additional components. For example, computer 400 may include an input unit 405 for receiving input operations and an output unit 406 for outputting processing results.

[0033] The processor 401 is a computing unit that executes the operating system and application programs. Examples of processors include CPUs (Central Processing Units) and GPUs (Graphics Processing Units), but the type of processor 401 is not limited to these. For example, the processor 401 may be a combination of a sensor and a dedicated circuit. The dedicated circuit may be a programmable circuit such as an FPGA (Field-Programmable Gate Array), or it may be another type of circuit.

[0034] The main memory unit 402 is a device that stores programs for realizing the information processing device 4 of the ground evaluation system 1, calculation results output from the processor 401, and the like. The main memory unit 402 is composed of, for example, at least one of ROM (Read Only Memory) and RAM (Random Access Memory).

[0035] The auxiliary storage unit 403 is generally a device capable of storing a larger amount of data than the main storage unit 402. The auxiliary storage unit 403 is composed of a non-volatile storage medium such as a hard disk or flash memory. The auxiliary storage unit 403 stores the program P1 and various data that cause the computer 400 to function as the information processing device 4 of the ground evaluation system 1. In this embodiment, the ground evaluation program that realizes the information processing device 4 of the ground evaluation system 1 is implemented as program P1.

[0036] The communication control unit 404 is a device that performs data communication with other computers via a communication network. The communication control unit 404 is composed of, for example, a network card or a wireless communication module.

[0037] As shown in Figure 5, the information processing device 4 includes, as functional components, an evaluation value calculation unit 41, an evaluation value determination unit 42, and a health determination unit 43. The evaluation value calculation unit 41 and the evaluation value determination unit 42 constitute an information processing unit in the narrow sense. These functional components are realized by the execution of a program by the processor 401. Furthermore, the information processing device 4 includes a main memory unit 402 and an output unit 406. Note that in Figure 5, the communication control unit 404 and input unit 405 shown in Figure 4 are omitted from the illustration.

[0038] The evaluation value calculation unit 41 receives the data to be evaluated D1. The evaluation value calculation unit 41 uses the data to be evaluated D1 to calculate the first evaluation value D21, the second evaluation value D22, the third evaluation value D23, and the fourth evaluation value D24. The evaluation value calculation unit 41 outputs the first evaluation value D21, the second evaluation value D22, the third evaluation value D23, and the fourth evaluation value D24 to the evaluation value determination unit 42. For example, the first evaluation value D21 is shear stress. The second evaluation value D22 is shear strain. The second evaluation value D22 is settlement. The fourth evaluation value D24 is rising wave energy. The evaluation value calculation unit 41 may also use other physical quantities as evaluation values. Furthermore, the evaluation value calculation unit 41 may generate and output at least one of the first evaluation value D21, the second evaluation value D22, the third evaluation value D23, and the fourth evaluation value D24.

[0039] The evaluation value calculation unit 41 includes a preprocessing unit 410, a shear stress calculation unit 411, a shear strain calculation unit 412, a settlement amount calculation unit 413, and a rising wave energy calculation unit 414.

[0040] The preprocessing unit 410 converts the acceleration included in the evaluation target data D1 into velocity and displacement using equations (1) and (2). Briefly, the preprocessing unit 410 performs an integration operation.

Number

Number

[0041] The shear stress calculation unit 411 obtains the shear stress using the following formula (3).

number

[0042] The density (ρ) of the ground 8 is obtained from a soil survey of the ground 8 conducted in advance and stored in the main memory unit 402. The shear stress calculation unit 411 reads the density (ρ) of the ground 8 from the main memory unit 402. The shear stress calculation unit 411 receives the horizontal acceleration component of evaluation point 81(i-1) and the horizontal acceleration component of evaluation point 81(i) from the preprocessing unit 410. The shear stress calculation unit 411 also receives the vertical Z depth of evaluation point 81(i-1) and the vertical Z depth of evaluation point 81(i) from the preprocessing unit 410.

[0043] The numerator of the second term on the right-hand side is the relative value between the horizontal acceleration component of evaluation point 81(i-1) and the horizontal acceleration component of evaluation point 81(i). Furthermore, the second term on the right-hand side (Z i-1 -Z i) is the difference between the vertical Z depth of evaluation point 81(i-1) and the vertical Z depth of evaluation point 81(i). In other words, it is the relative distance along the vertical Z between evaluation point 81(i-1) and evaluation point 81(i). Note that the second term on the right side (Z i-1 -Z i ) can be treated as a constant value, but by making it the relative distance along the vertical direction between evaluation point 81(i-1) and evaluation point 81(i), the shear stress (τ i This can improve the accuracy of ).

[0044] The shear strain calculation unit 412 obtains the shear strain using the following formula (4).

number

[0045] The shear strain calculation unit 412 receives the horizontal displacement of evaluation point 81(i-1) and the horizontal displacement of evaluation point 81(i) of the ground 8 from the preprocessing unit 410. Furthermore, the shear strain calculation unit 412 receives the vertical Z depth of evaluation point 81(i-1) and the vertical Z depth of evaluation point 81(i) of the ground 8 from the preprocessing unit 410.

[0046] In other words, the numerator of the first term on the right-hand side is the relative value between the displacement of evaluation point 81(i-1) and the displacement of evaluation point 81(i). Furthermore, the denominator of the first term on the right-hand side is the relative distance along the vertical direction from evaluation point 81(i-1) to evaluation point 81(i). Note that, similar to the shear stress calculation unit 411, the denominator of the first term on the right-hand side may be treated as a constant value, but by using the relative distance along the vertical direction from evaluation point 81(i-1) to evaluation point 81(i), the shear strain (γ i This can improve the accuracy of ).

[0047] The settlement amount calculation unit 413 may, for example, obtain the settlement amount (5) using the following formula (5) based on the method disclosed in Non-Patent Document 1.

number

[0048] Furthermore, shear strain (γ) and volumetric strain (ε) can be determined from triaxial tests using sampled ground from the target soil. V If the relationship ) is obtained, the test results may be used.

[0049] The rising wave energy calculation unit 414 obtains the rising wave energy using the following equation (6).

number

[0050] The rising wave energy calculation unit 414 receives the horizontal displacement of the evaluation point 81(i) of the ground 8 from the preprocessing unit 410. Furthermore, the rising wave energy calculation unit 414 receives the density (ρ) and shear wave velocity (V) of the ground 8 from the main memory unit 402. S )

[0051] The evaluation value determination unit 42 receives the first evaluation value D21 (shear stress), the second evaluation value D22 (shear strain), the third evaluation value D23 (settlement), and the fourth evaluation value D24 (upward wave energy) from the evaluation value calculation unit 41. The evaluation value determination unit 42 determines the evaluation value data D2. The determination of the evaluation value data D2 is to determine whether or not damage has occurred to the ground 8. The determination of the evaluation value data D2 is to determine whether or not liquefaction has occurred. Therefore, the evaluation result data D3 output by the evaluation value determination unit 42 indicates either "damage has occurred" or "no damage has occurred". Furthermore, the evaluation result data D3 indicates either "liquefaction has occurred" or "liquefaction has not occurred".

[0052] In other words, the evaluation value determination unit 42 performs an evaluation of the ground 8. Therefore, the evaluation value data D2 shows the evaluation result for the ground 8 and is not data that indicates the soundness of the structure 9 itself. The soundness of the structure 9 is determined by the soundness determination unit 43.

[0053] The conditions for determining the evaluation value data D2 may be set as appropriate depending on the specific situation in which the ground evaluation system 1 is applied. The conditions for determining whether or not damage has occurred to the ground 8 include "design shear strength (τ f An example is the maximum shear stress (τ). Furthermore, the shear strength τ of the ground material obtained from the mechanical test of the sampled specimen can be used as a judgment criterion. l This is a comparison with "the shear strength of the ground (τ lExamples of conditions for determining whether liquefaction has occurred include, for example, "maximum shear strain (γ) > 3.75%" or "cumulative energy ratio > 1". The choice of which of these conditions to use is appropriate. These conditions are pre-stored in the main memory unit 402. The evaluation value determination unit 42 reads the conditions corresponding to the evaluation value data D2 from the main memory unit 402 and executes the determination process.

[0054] The structural integrity determination unit 43 receives evaluation result data D3 from the evaluation value determination unit 42. The structural integrity determination unit 43 outputs the result "repair work required (structural integrity problem)" if the evaluation result data D3 is "damaged" and "liquefaction present", "damaged" and "no liquefaction", or "no damage" and "liquefaction present". In other words, the structural integrity determination unit 43 determines that there is a problem with the structural integrity of the structure 9 and outputs the determination result data D4. In that case, the structural integrity determination unit 43 causes the output unit 406 to inform the user 93 that there is a problem with the ground 8 that requires repair work.

[0055] The structural integrity determination unit 43 outputs the result "No repair work required (no structural integrity issues)" if the evaluation result data D3 is "No damage" and "No liquefaction". In other words, the structural integrity determination unit 43 determines that there are no structural integrity issues with the structure 9 and outputs the determination result data D4. In this case, the output unit 406 is instructed to inform the user 93 that there are no problems with the ground 8 that would require repair work.

[0056] The structural integrity determination unit 43 may include information in the determination result data D4 for determining whether repair work is necessary, in addition to the information of "damage present" or "no damage." In this case, the structural integrity determination unit 43 performs a process to arrange the various evaluation values ​​received from the evaluation value calculation unit 41 into a desired format. For example, the structural integrity determination unit 43 may perform a process to arrange the distribution of shear strain or shear stress into the format of a contour map. Furthermore, a failure margin contour map can also be obtained using the shear stress contour map. In the failure margin contour map, it can be determined that failure has occurred in the range where the failure margin exceeds 1. Moreover, since the extent of failure can be determined from the contour map, the scope of repair work can be minimized, contributing to a reduction in repair time and cost. The structural integrity determination unit 43 may then present the visualized information to the user 93. The user 93 may look at the distribution of shear strain shown in the contour map and determine whether repair work is necessary. In other words, the ground evaluation system 1 of this embodiment can be described as a shear stress visualization system within the ground, or as a shear strain visualization system within the ground.

[0057] In other words, the ground evaluation system 1 outputs at least one of the following: information that directly indicates whether or not there is a problem with the structural integrity of the structure 9, and information that allows the user 93 to determine whether or not there is a problem with the structural integrity of the structure 9.

[0058] Next, a ground evaluation method using the ground evaluation system 1 will be explained. Figure 6 is a flowchart showing the main steps of the ground evaluation method. The ground evaluation method includes the steps of: installing the sensor unit 2 in step S11; evaluating the characteristics of the soil sample in step S12; preparing the evaluation target data D1 in step S13; obtaining evaluation value data D2 in step S2; determining the evaluation value data D2 in step S3; and determining the soundness in step S4.

[0059] First, step S11 is performed to install the sensor unit 2. Step S11 may be performed in parallel with the construction of the structure 9. Alternatively, step S11 may be added retrospectively to a structure 9 that has already been constructed. When the sensor unit 2 is added retrospectively, for example, the sensors 21 can be installed at each evaluation point 81 by using a curved boring drilling method.

[0060] Step S12 is performed to evaluate the characteristics of the soil sample. In this step S12, the physical and mechanical properties of the in-situ sample are obtained. First, a field sample is taken at the same depth as the depth at which the sensor unit 2 will be installed. Then, the physical and mechanical properties are obtained by triaxial testing, etc. These properties include density, particle size characteristics, and stiffness. The obtained information is stored in the main memory unit 402. By utilizing the physical and mechanical properties, it becomes possible to determine the degree of damage to the ground 8, as well as liquefaction.

[0061] Next, step S13 is performed to prepare the data to be evaluated D1. This step S13 is performed by the information acquisition device 3 and the information processing device 4. When the data to be evaluated D1 that satisfies the conditions is input, the information acquisition device 3 passes the data to be evaluated D1 for a predetermined period to the information processing device 4. The information acquisition device 3 stores the data to be evaluated D1 in the main memory unit 402 or the auxiliary memory unit 403.

[0062] Next, step S2 is performed to prepare the data to be evaluated D1. This step S2 is performed by the evaluation value calculation unit 41. Step S2, which prepares the data to be evaluated D1, in other words, includes step S21, which obtains evaluation value data D2 using theoretical formulas shown in equations (1) to (6), etc. As a result of step S21, the evaluation value calculation unit 41 outputs the evaluation value data D2 (step S22). The evaluation value data D2 includes, for example, a first evaluation value D21 (shear stress), a second evaluation value D22 (shear strain), a third evaluation value D23 (settlement), and a fourth evaluation value D24 (upward wave energy).

[0063] Next, step S3 is performed to determine the evaluation value data D2. This step S3 is performed by the evaluation value determination unit 42. For example, the evaluation value determination unit 42 compares the first evaluation value D21 (shear stress) with the design value and the second evaluation value D22 (shear strain) with the design value (step S31). As a result, a result D31 of either "damage present" or "no damage" is obtained. The evaluation value determination unit 42 also performs a liquefaction determination based on the energy method (step S32). As a result, a result D31 of either "liquefaction present" or "no liquefaction" is obtained. As a result of step S3, evaluation result data D3 including results D31 and D32 is obtained.

[0064] Next, step S4 is performed to determine the soundness of the ground. This step S4 is performed by the soundness determination unit 43. If the evaluation result data D3 satisfies the following conditions, the soundness determination unit 43 outputs determination result data D41 indicating that damage requiring repair work has occurred in the ground 8 (there is a problem with its soundness) (step S41: YES). Then, necessary repairs or countermeasures are taken for the ground 8 (step S42). Condition 1: When evaluation result data D3 is "damaged" and "liquefaction present". Condition 2: When evaluation result data D3 is "damaged" and "no liquefaction". Condition 3: When evaluation result data D3 is "no damage" and "liquefaction present".

[0065] On the other hand, if the evaluation result data D3 does not satisfy the above conditions, in other words, if it satisfies the following conditions, then the judgment result data D42 is output, indicating that no damage requiring repair work has occurred in the ground 8 (there are no problems with its soundness) (step S41: NO). In this case, the ground evaluation method is terminated. Condition 4: When evaluation result data D3 is "no damage" and "no liquefaction".

[0066] First, we will briefly describe the comparative example's ground evaluation system, and then we will explain the ground evaluation system 1 of this embodiment, focusing on the differences.

[0067] Figure 7 is a functional block diagram of the comparative example ground evaluation system 6. The comparative example ground evaluation system 6 includes a ground surface sensor 62, an information collection device 63, and an information processing device 64.

[0068] The comparative example's ground evaluation system 6 differs from the embodiment's ground evaluation system 1 in that the ground surface sensor 62 is located on the ground surface 82. In other words, the comparative example's ground evaluation system 6 does not directly measure the evaluation target data at evaluation points 81 set inside the ground 8. The comparative example's ground evaluation system 6 estimates the evaluation target data D642 at evaluation points 81 set inside the ground 8.

[0069] The comparative example ground evaluation system 6 uses information received by the ground surface sensor 62 to estimate the acceleration, velocity, and displacement input to the evaluation point 81 using the input value estimation unit 641. The input value estimation unit 641 uses the information received by the ground surface sensor 62 as input values ​​and outputs the acceleration, velocity, and displacement (data D641) for each evaluation point 81 to perform estimation calculations.

[0070] Next, the comparative example ground evaluation system 6 takes the acceleration, velocity, and displacement (data D641) estimated for each evaluation point 81 as input and estimates the response of the evaluation area 80. This estimation yields the estimated evaluation target data D642. This estimation requires input for each evaluation point 81 (acceleration, velocity, and displacement (data D641)) and a numerical model M642 that mechanically simulates the evaluation area 80.

[0071] In other words, the comparative example's ground evaluation system 6 obtains the evaluation target data D642, which is an estimated value, from the evaluation target data D1 obtained by direct measurement by the embodiment's ground evaluation system 1, through at least two estimation calculations. The characteristics of the evaluation region represented by the numerical model M641 do not perfectly match the characteristics of the actual evaluation region 80. The numerical model M641 potentially contains some degree of difference from the actual one. Furthermore, the numerical model M642, which mechanically simulates the evaluation region 80, includes several variables. These variables include density and stiffness. Estimation using the numerical model M642 requires inputting certain numerical values ​​for these variables. Even when using measured results, these numerical values ​​do not perfectly match the characteristics of the actual evaluation region 80.

[0072] Furthermore, the estimation calculations using these numerical models M641 and M642 are highly computationally intensive. Therefore, obtaining results requires a significant amount of computing power. In other words, obtaining results requires both time and expense.

[0073] In contrast, the ground evaluation system 1 of the embodiment includes a sensor 21 that obtains evaluation target data D1 for evaluating the soundness of the ground 8, which is at least one of the acceleration and velocity acting on an evaluation point 81 along a vertical reference line 83 with respect to the ground surface 82 in the ground 8, and an information processing device 4 that obtains evaluation value data D2 for evaluating the ground 8 using the evaluation target data D1. The information processing device 4 has an evaluation value calculation unit 41 that obtains evaluation value data D2 using at least one of the horizontal components of the acceleration and velocity included in the evaluation target data D1.

[0074] The ground evaluation system 1 and ground evaluation method of this embodiment obtain evaluation target data D1 for each evaluation point 81 directly using the sensor unit 2 without calculation. Furthermore, the calculation to obtain evaluation value data D2 from the evaluation target data D1 obtained from the sensor unit 2 can be performed using a low-intensity calculation, rather than a computationally intensive iterative convergence calculation like those using numerical models. Therefore, the ground evaluation system 1 of this embodiment can obtain the information required for ground evaluation in a short time using simple calculations.

[0075] Furthermore, since the ground evaluation system 1 of this embodiment uses earthquake measurement data (evaluation target data D1), it is possible to directly obtain the shear stress and shear strain generated inside the ground 8. In addition, the ground evaluation system 1 of this embodiment can evaluate the presence or absence of liquefaction and the degree of damage inside the ground 8 through simple calculations, so the results can be obtained quickly and at low cost. Since the soundness of the ground 8 can be proven by measured values ​​with the ground evaluation system 1 of this embodiment, structures 9 that are judged to have not been damaged can be put into use immediately after the earthquake. The ground evaluation system 1 of this embodiment can directly confirm the presence or absence of damage to structures 9 by measured values, rather than by calculated values ​​from analysis. The results obtained with the ground evaluation system 1 of this embodiment can also be used to evaluate the validity of the results obtained with the ground evaluation system 6 of the comparative example. Furthermore, the design can be made more accurate from the observation results. Since the ground evaluation system 1 of this embodiment can identify the degree and extent of damage, it is advantageous for rationalizing repair work.

[0076] The ground evaluation system and ground evaluation method of the present invention are not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the present invention.

[0077] In this embodiment, acceleration and / or velocity are exemplified as the evaluation data D1. The calculation of the evaluation value can be performed by obtaining the other two pieces of information if one of the following pieces of information (acceleration, velocity, or displacement) is available. For example, the evaluation data D1 may be strain at the evaluation point 81. In this case, an optical fiber may be used as the sensor 21. The strain can be obtained based on the Brillouin scattered light and Rayleigh scattered light generated by the optical fiber. The optical fiber as the sensor 21 can be placed inside the ground 8 by bending boring. The direction in which the optical fiber is placed may be the vertical Z direction or the horizontal direction (X or Y). When an optical fiber is used as the sensor 21, continuous evaluation data D1 can be obtained, resulting in more accurate results. Furthermore, since continuous evaluation data D1 can be obtained with a single optical fiber, the number of sensors 21 (number of optical fibers) required to construct the sensor unit 2 can be reduced. Moreover, 3D data can be acquired with a single optical fiber, and evaluation data D1 in the 3-axis direction can be obtained by decomposing the 3D data. In addition, optical fibers are highly durable and can withstand long-term use.

[0078] [Note] This disclosure includes the following components:

[0079] This disclosure includes [1] a ground evaluation system for evaluating the ground on which a structure is installed, A first sensor for obtaining first evaluation target data for evaluating the soundness of the ground, which is at least one of the acceleration and velocity acting on a first evaluation point set at a first depth along a first vertical reference line with respect to the ground surface in the ground; A second sensor that obtains second evaluation target data, which is at least one of the acceleration and velocity acting on a second evaluation point set at a second depth different from the first depth along a second vertical reference line with respect to the ground surface in the aforementioned ground, The system comprises an information processing unit that obtains an evaluation value for evaluating the ground using the first evaluation target data and the second evaluation target data, The aforementioned information processing unit has an evaluation value calculation unit that obtains the evaluation value using at least one of the horizontal components of acceleration and velocity included in the first evaluation target data and at least one of the horizontal components of acceleration and velocity included in the second evaluation target data, and is a ground evaluation system.

[0080] In this disclosure, [2] "The ground evaluation system according to [1] above, wherein the evaluation value calculation unit corrects the evaluation value using at least one of the vertical components of acceleration and velocity included in the first evaluation target data and at least one of the vertical components of acceleration and velocity included in the second evaluation target data."

[0081] In this disclosure, [3] "The ground evaluation system according to [1] or [2] above, wherein the evaluation value calculation unit obtains a relative value between the first evaluation target data and the second evaluation target data."

[0082] This disclosure relates to the ground evaluation system according to any one of the above [1] to [3], further comprising: [4] a third sensor and a fourth sensor arranged at different depths along a second vertical reference line that is horizontally spaced apart from the first vertical reference line.

[0083] This disclosure relates to [5] "a ground evaluation method for evaluating the ground on which a structure is installed, The steps include installing a first sensor to obtain first evaluation target data for evaluating the soundness of the ground, which is at least one of the acceleration and velocity acting on a first evaluation point set at a first depth along a first vertical reference line with respect to the ground surface in the ground; The steps include installing a second sensor to obtain second evaluation target data, which is at least one of the acceleration and velocity acting on a second evaluation point set at a second depth different from the first depth along a second vertical reference line with respect to the ground surface in the aforementioned ground, The process includes the step of obtaining an evaluation value for evaluating the ground using the first evaluation target data and the second evaluation target data, The step of obtaining the aforementioned evaluation value is a ground evaluation method that obtains the evaluation value using at least one of the horizontal components of acceleration and velocity included in the first evaluation target data and at least one of the horizontal components of acceleration and velocity included in the second evaluation target data.

[0084] In this disclosure, [6] "The step of installing the first sensor and the step of installing the second sensor are performed in parallel with the construction of the structure, and are the ground evaluation method described in [5] above."

[0085] In this disclosure, [7] "The step of installing the first sensor and the step of installing the second sensor are performed after the construction of the structure is completed, in the ground evaluation method described in [5] above." [Explanation of Symbols]

[0086] 1...Ground evaluation system, 2...Sensor unit, 21...Sensor, 3...Information collection device, 4...Information processing device, 41...Evaluation value calculation unit, 410...Preprocessing unit, 411...Shear stress calculation unit, 412...Shear strain calculation unit, 413...Settlement amount calculation unit, 414...Upward wave energy calculation unit, 42...Evaluation value determination unit, 43...Soil integrity determination unit, 8...Ground, 80...Evaluation area, 81...Evaluation point, 82...Ground surface, 83...Vertical reference line, 9...Structure, D1...Evaluation target data, D2...Evaluation value data, D3...Evaluation result data, D4...Judgment result data.

Claims

1. A ground evaluation system for evaluating the ground on which a structure is built, A first sensor for obtaining first evaluation target data for evaluating the soundness of the ground, which is at least one of the acceleration and velocity acting on a first evaluation point set at a first depth along a first vertical reference line with respect to the ground surface in the ground; A second sensor that obtains second evaluation target data, which is at least one of the acceleration and velocity acting on a second evaluation point set at a second depth different from the first depth along a second vertical reference line with respect to the ground surface in the aforementioned ground, The system comprises an information processing unit that obtains an evaluation value for evaluating the ground using the first evaluation target data and the second evaluation target data, The ground evaluation system includes an information processing unit which obtains a relative value between at least one of the horizontal components of acceleration and velocity included in the first data to be evaluated and at least one of the horizontal components of acceleration and velocity included in the second data to be evaluated, and an evaluation value calculation unit which obtains the evaluation value by performing calculations using the relative value and the difference in depth between the first evaluation point and the second evaluation point.

2. A ground evaluation system for evaluating the ground on which a structure is installed, A first sensor for obtaining first evaluation target data for evaluating the soundness of the ground, which is at least one of the acceleration and velocity acting on a first evaluation point set at a first depth along a first vertical reference line with respect to the ground surface in the ground; A second sensor that obtains second evaluation target data, which is at least one of the acceleration and velocity acting on a second evaluation point set at a second depth different from the first depth along a second vertical reference line with respect to the ground surface in the aforementioned ground, The system comprises an information processing unit that obtains an evaluation value for evaluating the ground using the first evaluation target data and the second evaluation target data, The information processing unit has an evaluation value calculation unit that obtains the evaluation value using at least one of the horizontal components of acceleration and velocity included in the first evaluation target data and at least one of the horizontal components of acceleration and velocity included in the second evaluation target data. A ground evaluation system in which the evaluation value calculation unit corrects the evaluation value using at least one of the vertical components of acceleration and velocity included in the first evaluation target data and at least one of the vertical components of acceleration and velocity included in the second evaluation target data.

3. The ground evaluation system according to claim 1 or 2, further comprising a third sensor and a fourth sensor arranged at different depths along a second vertical reference line that is horizontally spaced apart from the first vertical reference line.

4. A ground evaluation method for evaluating the ground on which a structure is built, The steps include installing a first sensor to obtain first evaluation target data for evaluating the soundness of the ground, which is at least one of the acceleration and velocity acting on a first evaluation point set at a first depth along a first vertical reference line with respect to the ground surface in the ground; The steps include installing a second sensor to obtain second evaluation target data, which is at least one of the acceleration and velocity acting on a second evaluation point set at a second depth different from the first depth along a second vertical reference line with respect to the ground surface in the aforementioned ground, The process includes the step of obtaining an evaluation value for evaluating the ground using the first evaluation target data and the second evaluation target data, A ground evaluation method in which the step of obtaining the evaluation value is to obtain a relative value between at least one of the horizontal components of acceleration and velocity included in the first data to be evaluated and at least one of the horizontal components of acceleration and velocity included in the second data to be evaluated, and to obtain the evaluation value by performing a calculation using the relative value and the difference in depth between the first evaluation point and the second evaluation point.

5. A ground evaluation method for evaluating the ground on which a structure is installed, The steps include installing a first sensor to obtain first evaluation target data for evaluating the soundness of the ground, which is at least one of the acceleration and velocity acting on a first evaluation point set at a first depth along a first vertical reference line with respect to the ground surface in the ground; The steps include installing a second sensor to obtain second evaluation target data, which is at least one of the acceleration and velocity acting on a second evaluation point set at a second depth different from the first depth along a second vertical reference line with respect to the ground surface in the aforementioned ground, The process includes the step of obtaining an evaluation value for evaluating the ground using the first evaluation target data and the second evaluation target data, The step of obtaining the evaluation value involves obtaining the evaluation value using at least one of the horizontal components of acceleration and velocity included in the first data to be evaluated, and at least one of the horizontal components of acceleration and velocity included in the second data to be evaluated, A ground evaluation method that corrects the evaluation value using at least one of the vertical components of acceleration and velocity included in the first evaluation target data and at least one of the vertical components of acceleration and velocity included in the second evaluation target data.

6. The ground evaluation method according to claim 4 or 5, wherein the steps of installing the first sensor and installing the second sensor are carried out in parallel with the construction of the structure.

7. The ground evaluation method according to claim 4 or 5, wherein the steps of installing the first sensor and installing the second sensor are performed after the construction of the structure is completed.

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