JP6614549B2 - Bearing capacity estimation device - Google Patents

Description

  The present invention relates to a support force estimation device, and more particularly to a support force estimation device that estimates a support force of a ground when an earthquake occurs.

  When building a structure on the ground, since the strength of the ground changes when an earthquake occurs, the strength of the ground in the event of an earthquake is estimated in advance to calculate the bearing capacity of the ground in the event of an earthquake. It is demanded. Conventionally, when estimating the strength of the ground when an earthquake occurs, detailed analysis such as seismic response analysis of the ground has been performed, but detailed analysis of the ground requires time and effort. The structure is a concept including an architectural structure such as an office building or a school, and a civil engineering structure such as a bridge or a road pier.

  Prior to ground improvement, as a conventional technology to deal with such problems, a specimen having the same specifications as the ground characteristics to be estimated was created, and a laboratory experiment was conducted on the specimen, and data on the relationship between shear wave velocity and strength were obtained. An estimation method has been proposed in which the regression curve is obtained by formulating and the measurement result of the shear wave velocity obtained on the ground where the ground improvement is progressing is applied to the regression curve to estimate the ground strength after the improvement in the original position. (For example, Patent Documents 1 and 2).

Japanese Patent No. 4496480 Japanese Patent No. 4120809

  The above prior art only measures the shear wave velocity of the ground and estimates the strength of the ground due to ground improvement, and does not calculate the bearing capacity of the ground when an earthquake occurs.

  In view of the above facts, an object of the present invention is to provide a bearing capacity estimation device capable of calculating the bearing capacity of the ground when an earthquake occurs.

  In order to achieve the above object, the bearing capacity estimation device according to the present invention uses a specimen collected from a plurality of grounds having different ground constants, and uses the ground stress, maximum stress, strain, maximum strain, energy and maximum energy. Using the first deriving means for deriving the correspondence relationship between any one of the above and the strength change rate of the ground for each of the plurality of grounds and the ground constant of the ground to be estimated, and inputting an assumed earthquake waveform to receive an earthquake response Second derivation means for deriving any one of stress, maximum stress, strain, maximum strain, energy and maximum energy of the estimation target ground by analysis, the correspondence relationship derived by the first derivation means, the stress, An estimation means for estimating an intensity when an earthquake having the earthquake waveform of the estimation target ground occurs using any one of maximum stress, strain, maximum strain, energy, and maximum energy. , And a, a calculating means for calculating the bearing capacity of the case from the intensity when the earthquake of the estimated target ground deduced, that the earthquake of the estimated target ground is generated by the estimating means.

  According to this bearing capacity estimation device, the first derivation means uses a plurality of ground specimens having different ground constants, and the ground stress, maximum stress, strain, maximum strain, energy and maximum energy, The corresponding relationship with the intensity change rate is derived for each of the plurality of grounds. Further, the second derivation means inputs the seismic waveform using the ground constant of the original ground, and any one of stress, maximum stress, strain, maximum strain, energy, and maximum energy of the estimation target ground by seismic response analysis is obtained. Derived.

  As described above, according to the bearing capacity estimation device of the present invention, any one of ground stress, maximum stress, strain, maximum strain, energy, and maximum energy derived using a plurality of ground specimens having different ground constants is used. , Using the relationship between the ground strength change rate and the stress, maximum stress, strain, maximum strain, energy, and maximum energy when an earthquake occurs in the ground to be estimated. Estimate the strength when an earthquake occurs, and calculate the bearing capacity when an earthquake occurs on the estimated ground. As a result, in the present invention, the bearing capacity of the ground when an earthquake occurs can be easily calculated.

  In the bearing capacity estimation device according to the present invention, the estimation unit adjusts the stress, the maximum stress, the strain, the maximum strain, the energy, and the stress adjusted according to the correspondence and the weight of the structure on the estimation target ground. You may make it estimate the intensity | strength at the time of the occurrence of the said earthquake of the said estimation object ground using either the maximum energy and the inertia force converted from the acceleration obtained by the earthquake response analysis. Thereby, even when there is a structure on the ground, the bearing capacity of the ground directly under the structure when an earthquake occurs can be easily calculated from the ground around the structure.

  According to the present invention, it is possible to easily calculate the bearing capacity of the ground when an earthquake occurs.

It is a block diagram which shows the structure of the supporting force estimation apparatus which concerns on embodiment. It is a schematic diagram which shows the structure of the non-volatile memory which concerns on embodiment. It is a flowchart which shows the flow of a process of the estimation process program which concerns on embodiment. It is a diagram which shows the G-gamma curve which shows the relationship between the shear rigidity G of a ground, and the shear strain (gamma), and the h-gamma curve which shows the relationship between the damping factor h and the shear strain (gamma). It is a graph which shows an example of the relation between the half amplitude of repetitive distortion and ground strength concerning an embodiment. It is a graph which shows another example of the relation between the half amplitude of repetitive distortion and ground strength concerning an embodiment. It is a chart which shows an example of the relationship between repetitive distortion which concerns on embodiment, the frequency | count of repetition, and ground strength. It is a mimetic diagram for explaining the derivation method of the ground constant of the original ground concerning an embodiment. It is a graph which shows an example of the time history of the input acceleration waveform showing the earthquake waveform of an earthquake motion. It is a schematic diagram for demonstrating the calculation method of the bearing capacity of the raw ground which concerns on embodiment. It is a schematic diagram for demonstrating the calculation method of the supporting force of an original ground in case the structure is constructed just above the original ground in the supporting force estimation apparatus which concerns on embodiment. It is a schematic diagram which shows the analysis mesh used in the Example of this embodiment. It is a graph which shows the time history of the input acceleration waveform showing the earthquake waveform of the ground motion used in the Example of this embodiment. It is a graph showing the relationship between the depth of the ground estimated in the Example of this embodiment, and the maximum shear strain of the ground. It is a schematic diagram which shows the relationship between the ground strength before the earthquake of the ground estimated in the Example of this embodiment, and the ground strength after the earthquake of the ground. It is a schematic diagram which shows the analysis mesh used when calculating the supporting force of the ground in the Example of this embodiment. It is a figure which shows the analysis result of the bearing capacity after the earthquake of the ground at the time of performing an earthquake response analysis in the Example of this embodiment.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

  In order to evaluate whether or not the ground can be endured without being destroyed even when an earthquake occurs, the bearing capacity estimation device 10 according to the present embodiment has a ground on which no structure is constructed, and the structure Calculate the bearing capacity of the constructed ground in advance.

  Therefore, the bearing capacity estimation apparatus 10 according to the present embodiment uses a plurality of ground specimens having different ground constants, and the number of repetitions, repeated strains, and repeated stresses as forces acting on the ground when an earthquake occurs. By giving at least one specimen to the specimen, the earthquake is simulated and the relationship between the ground stress, maximum stress, strain, maximum strain, energy and maximum energy and the strength change rate of the ground is shown. Derived for each of multiple grounds. Further, the bearing capacity estimation device 10 inputs any seismic waveform using the ground constant of the estimation target ground, and any one of stress, maximum stress, strain, maximum strain, energy, and maximum energy of the estimation target ground by the seismic response analysis. Is derived.

  Further, the bearing capacity estimation device 10 is derived from the correspondence between the ground stress, the maximum stress, the strain, the maximum strain, the energy and the maximum energy and the strength change rate of the ground, and the ground response analysis with respect to the seismic waveform. The strength when an earthquake occurs in the estimation target ground is estimated using any of the stress, maximum stress, strain, maximum strain, energy, and maximum energy of the estimation target ground. Furthermore, the bearing capacity estimation apparatus 10 calculates the bearing capacity when an earthquake occurs on the estimation target ground from the strength when an earthquake occurs on the estimated estimation target ground.

  In the present embodiment, the original ground is described as the estimation target ground. In this embodiment, “strain” is a generic term for principal strain, shear strain, etc., “stress” is a generic term for average stress, principal stress, shear stress, etc., and “energy” is strain and stress. Multiply with and reduce to half.

  As shown in FIG. 1, the support force estimation apparatus 10 according to this embodiment includes a controller 12 that controls the entire apparatus. The controller 12 also includes a CPU (Central Processing Unit) 14 that executes various processes including an estimation process, which will be described later, and a ROM (Read Only Memory) 16 that stores programs used for the processing of the CPU 14 and various information. ing. The controller 12 also includes a RAM (Random Access Memory) 18 that temporarily stores various data as a work area of the CPU 14, and a non-volatile memory 20 that stores various programs and various information used for processing of the CPU 14. ing. Further, the controller 12 includes an I / O interface 22 for inputting / outputting data to / from an external device connected to the supporting force estimation device 10. Connected to the I / O interface 22 are an operation unit 24 operated by a user, a display unit 26 that displays various types of information, and a communication unit 28 that communicates with an external device.

  As shown in FIG. 2, the nonvolatile memory 20 includes M pieces of first intensity change information 30-1 to M-th intensity change information 30-M, which will be described later, as information for performing an estimation process, which will be described later. And the ground constant information 32 of the original ground is stored, and earthquake waveform information 34 indicating the earthquake waveform of the earthquake to be analyzed is stored in advance.

  Next, with reference to FIG. 3, the operation of the estimation process executed by the CPU 14 of the support force estimation apparatus 10 according to the present embodiment when an execution instruction is input by the user will be described as an example. Note that the estimation processing program is stored in advance in the nonvolatile memory 20, and the above-described hardware resources and the program cooperate with each other when the CPU 14 reads out and executes the estimation processing program. Is realized.

  First, in step S101, the result of the loading test of a plurality of sample grounds having different ground constants is acquired.

  In a plurality of grounds having different ground constants, the relationship between the shear strain γ and the shear rigidity G is different for each ground. As an example, FIG. 4 shows a G-γ curve showing the relationship between the shear stiffness G of the ground and the shear strain γ, and an h-γ curve showing the relationship between the damping rate h of the ground shear stiffness G and the shear strain γ. It is shown for each ground with different ground constants. That is, as shown in FIG. 4, even when the same shear strain γ is applied to the ground, the attenuation rate h of the ground shear stiffness G varies depending on the ground constant of the ground, and naturally the strength of the ground also varies.

  Therefore, in the present embodiment, in order to investigate the correspondence between the stress, the maximum stress, the strain, the maximum strain, the energy and the maximum energy of a plurality of grounds having different ground constants and the ground strength, a plurality of ground constants having different ground constants are used. Obtain the results of a loading test in the laboratory for each of the soil specimens collected from the ground.

  In the present embodiment, for example, even if the ground has the same density, considering that the ground strength is different between the clay-rich ground and the sand-rich ground, the ground density index and the ground strength index are considered as ground constants. Is used. However, the index of the ground constant is not limited to this, and any one of ground density, ground strength, saturation, fine particle content, uniformity coefficient, curvature coefficient, soil consistency, etc. may be used. Or a combination of a plurality of them may be used.

  Moreover, in this embodiment, after performing a repeated loading test for each specimen while changing the repeated stress width or the repeated strain width and the number of repetitions, a soil indoor element test is performed by a monotonous loading test. When changing the strain width repeatedly, the loading test is performed while changing the strain width to, for example, 1 [%], 5 [%], and 10 [%] of the width of the specimen. When changing the number of repetitions, the loading test is performed while changing the distortion of a predetermined width to, for example, 5 times, 10 [times], 20 [times], and 100 [times]. In the monotonic loading test, the ground strength is measured by continuously applying a constant stress or strain under an equal volume or an equal pressure until the specimen undergoes shear failure.

  When the stress width is repeatedly changed, the loading test is performed while changing the stress width to, for example, 1 [%], 5 [%], and 10 [%] of the initial stress. Alternatively, the loading test is performed while changing the stress width to, for example, 0.1σf, 0.2σf, 0.5σf with respect to the strength σf of the ground.

  In addition, the method of investigating the correspondence relationship between the ground strength and any of the stress, maximum stress, strain, maximum strain, energy, and maximum energy of a plurality of grounds having different ground constants is not limited to this, and the stress of the ground or the maximum stress Any other method can be used as long as it can obtain any one of the relationship between the ground strength, the ground strain or the maximum strain and the ground strength, and the ground energy or the maximum energy and the ground strength. There may be.

  In addition, as a loading test method when obtaining the bearing capacity of the ground, for example, when obtaining ground strength and deformation characteristics when axially compressed in a non-consolidated and undrained state, the following are set as the standards of the Geotechnical Society The technique disclosed in Reference Example 1 can be adopted.

[Reference Example 1]
"Soil non-consolidation drainage triaxial compression test method", JGS0521-2000.

  In addition, for example, when the constant volume shear strength is obtained by shearing on one surface perpendicular to the direction in which the normal force is applied with the volume of the one-dimensionally consolidated soil kept constant in the shear box, The technique disclosed in Reference Example 2 below, which is defined as a standard, can be employed.

[Reference Example 2]
"Consolidation constant volume single surface shear test method of soil", JGS0560-2000

  In addition, for example, for soil that is densely pressed in an isotropic stress state, using a repeated triaxial test device, the single amplitude or repeated stress amplitude ratio of the repeated axial differential stress in the undrained state and the predetermined both amplitude axial strain And when calculating | requiring the relationship with the frequency | count of repeated loading until it reaches | attains a predetermined excess pore water pressure, the method currently disclosed by the following reference example 3 established as a geotechnical society standard can be employ | adopted.

[Reference Example 3]
"Repeated soil undrained triaxial test method", JGS0541-2000

  In the next step S103, for each specimen, a correspondence relationship between any one of stress, maximum stress, strain, maximum strain, energy and maximum energy and the intensity change rate is derived. In addition, the intensity change rate here is an intensity change rate when the ground strength before adding is set to 1.

  In the present embodiment, for example, for each of a plurality of (for example, M) ground specimens having different ground constants, a relational expression indicating a correspondence relationship between the maximum strain and the strength change rate from the result obtained by the loading experiment. Is derived. Then, for each of the M grounds, information indicating a correspondence relationship between the maximum strain and the intensity change rate is stored in the nonvolatile memory 20 as the first intensity change information 30-1 to the Mth intensity change information 30-M.

  When deriving the relational expression, as shown in FIG. 5A and FIG. 5B as an example, an approximate expression representing the correspondence between the half amplitude of the repeated strain and the ground strength is created from the experimental results by the least square method or the like. . As shown in FIG. 5A, in the correspondence between the single amplitude of repeated strain and the ground strength, as shown in FIG. 5A, the ground strength may decrease as the maximum amplitude of the maximum strain increases. As shown, the ground strength may increase as the half amplitude of the maximum strain increases.

  In this embodiment, the strength at the time of monotonic loading has a peak displacement amount or strain amount due to the relationship between the load and the displacement amount or the relationship between the stress and the strain amount, as defined by the Geotechnical Society standards. The load or stress at the time, or the load or stress when the displacement or strain is 15%. However, the strength at the time of monotonous loading is not limited to this, and can be appropriately changed, such as a load or a stress when the amount of displacement or strain becomes 20%, for example.

  Further, when deriving the above-described correspondence relationship, a stress amplitude ratio of repetitive stress may be used instead of the single amplitude of repetitive strain. When the stress amplitude ratio of the repeated stress is used, an approximate expression representing the correspondence relationship between the amplitude ratio of the repeated stress and the ground strength is created by the least square method or the like.

  Alternatively, when deriving the above-described correspondence, the number of repetitions may be used instead of the single amplitude of the repeated distortion. When the number of repetitions is used, an approximate expression representing the correspondence between the number of repetitions and the ground strength is created by the least square method or the like.

  Alternatively, when deriving the above-described correspondence, the energy amplitude ratio of energy may be used instead of the half amplitude of repeated distortion. In the case of using the energy amplitude ratio, an approximate expression representing the correspondence between the energy amplitude ratio and the ground strength is created by the least square method or the like.

  Further, instead of the correspondence between the maximum strain and the strength change rate, when obtaining the correspondence between the stress or the maximum stress and the strength change rate, as in the case of obtaining the correspondence between the maximum strain and the strength change rate, For example, for each of a plurality of ground specimens having different ground constants, a relational expression indicating a correspondence relationship between the stress or the maximum stress and the strength change rate is derived from the result obtained by the loading experiment.

  Further, instead of the correspondence between the maximum strain and the intensity change rate, when obtaining the correspondence between the energy or the maximum energy and the intensity change rate, as in the case of obtaining the correspondence between the maximum strain and the intensity change rate, For example, for each of a plurality of ground specimens having different ground constants, a relational expression indicating a correspondence relationship between energy or maximum energy and intensity change rate is derived from the result obtained by the loading experiment.

  In addition, instead of creating a relational expression showing the correspondence between the strain or maximum strain and the intensity change rate, as shown in FIG. 6 as an example, a chart showing the correspondence between the repeated strain and the number of repetitions and the intensity change rate is shown. It may be derived. In the example shown in FIG. 6, the change rate of the ground strength is shown for the case where the repeated strain is changed and the case where the number of repetitions is changed. For example, when the number of repetitions is 5 and the repetition strain is 1%, the intensity change rate is 98%, and when the number of repetitions is 5 and the repetition strain is 5%, the intensity change rate is 95%. . In addition, the intensity change rate here is with respect to the intensity | strength of the ground which has not received the repetition history.

  Further, in the present embodiment, a correspondence relationship between any one of stress, maximum stress, strain, maximum strain, energy, and maximum energy and the intensity change rate is used, but the present invention is not limited thereto. For example, a correspondence relationship between an average value of strain, a median value of strain, and the like and an intensity change rate may be used. Further, for example, a correspondence relationship between an average value of stress, a median value of stress, and the intensity change rate may be used. Further, for example, a correspondence relationship between an average value of energy, a median value of energy, and the like and an intensity change rate may be used.

  In the next step S105, the ground constant when the earthquake of the original ground has not occurred is acquired.

  In the present embodiment, the ground constant is acquired using the soil of the original ground, which is the target of calculation of the bearing capacity of the ground, acquired by boring. At this time, as in the case of the sample ground specimen described above, an index of the density of the ground and an index of the ground strength of the ground are used as the ground constant.

  Moreover, in this embodiment, as shown in FIG. 7 as an example, a plurality of (for example, N) divided regions 50-1 in the depth direction (vertical direction) of the specimen 50 of the original ground obtained by boring, 50-2,..., 50- (N-1), 50-N, and divided into a plurality of divided regions 50-1, 50-2, ..., 50- (N-1), 50-N, Get the ground constant.

  Then, information indicating the ground constant for each of the plurality of divided regions 50-1, 50-2,..., 50- (N-1), 50-N is stored in the nonvolatile memory 20 as ground constant information 32 of the original ground. Remember.

  In the next step S107, earthquake waveform information indicating the earthquake waveform of the earthquake to be analyzed is acquired. In the present embodiment, the earthquake waveform information is acquired by reading the earthquake waveform information 34 stored in the nonvolatile memory 20. As an example, the seismic waveform is represented by time and acceleration as shown in FIG. In this embodiment, earthquake waveform information of an earthquake that is expected to occur is acquired, but not limited to this, in order to determine a decrease in ground strength after an earthquake has occurred, earthquake waveform information of an earthquake that has already occurred You may get

  In the next step S109, the seismic waveform indicated by the acquired seismic waveform information is input, and any one of the stress, maximum stress, strain, maximum strain, energy and maximum energy of the original ground is analyzed by the seismic response analysis of the one-dimensional columnar model. To derive.

  In this embodiment, as shown in FIG. 9 as an example, for example, for each of the divided areas 50-1, 50-2,..., 50- (N-1), 50-N, based on the ground constant, The maximum distortion is derived.

  Any seismic response analysis method can be used as long as it can derive any of ground stress, maximum stress, strain, maximum strain, energy and maximum energy by inputting an earthquake waveform. good. As a method of the earthquake response analysis, for example, a known method, a method based on a ground vibration analysis program “SHAKE” using an equivalent linearization method, a ground response analysis such as embankment and irregular ground, and a ground and a structure A method using “FLUSH”, which is a dynamic interaction analysis program, can be used. Again, instead of the stress or the maximum stress, any one of an average value, a median value, and a maximum value of the stress may be used. Further, instead of the distortion or the maximum distortion, any one of an average value, a median value, and a maximum value of the distortion may be used. Further, instead of energy or maximum energy, any one of an average value, median value, and maximum value of energy may be used.

  In the next step S111, the correspondence between the stress of the sample ground, the maximum stress, the strain, the maximum strain, the energy and the maximum energy derived in step S103, and the strength change rate of the sample ground, and the derived in step S109. From the stress of the original ground, the maximum stress, the strain, the maximum strain, the energy, and the maximum energy, the ground strength of the original ground when an earthquake having the input earthquake waveform occurs is estimated.

  In the present embodiment, as shown in FIG. 9 as an example, for example, for each of the divided regions 50-1, 50-2,..., 50- (N−1), 50-N, the maximum distortion is based on the ground constant. And the correspondence between the intensity change rate. Then, for each of the divided regions 50-1, 50-2,..., 50- (N-1), 50-N, the maximum distortion of the original ground derived in step S109 and the maximum distortion and intensity change derived in step S103. The ground strength of the original ground when an earthquake with the input seismic waveform occurs is estimated from the correspondence with the rate.

  Alternatively, for each of the divided regions 50-1, 50-2, ..., 50- (N-1), 50-N, the stress or maximum stress of the original ground derived in step S109 and the stress or maximum derived in step S103. From the correspondence between the stress and the rate of change in strength, the ground strength of the original ground when an earthquake having the input seismic waveform occurs is estimated.

  Alternatively, for each of the divided regions 50-1, 50-2, ..., 50- (N-1), 50-N, the energy or maximum energy of the original ground derived in step S109 and the energy or maximum derived in step S103. The ground strength of the original ground when an earthquake having the input seismic waveform occurs is estimated from the correspondence relationship between the energy and the intensity change rate.

  In the next step S113, the bearing capacity of the original ground in the event of an earthquake is calculated from the ground strength of the original ground in the event of an earthquake estimated in step S111, and execution of the program of this estimation process is completed. To do.

  In this embodiment, as shown in FIG. 9 as an example, the ground strength of each of the divided areas 50-1, 50-2, ..., 50- (N-1), 50-N of the original ground is used. Calculate the bearing capacity of the ground. In this embodiment, the bearing capacity of the original ground is calculated by performing an arc slip analysis.However, the method of calculating the bearing capacity of the original ground is not limited to this, and by performing an ultimate balance analysis, a rigid plastic analysis, etc. The supporting force of the ground may be calculated.

  In addition, instead of using the ground strength of each of the divided areas 50-1, 50-2, ..., 50- (N-1), 50-N of the original ground, the divided areas 50-1, 50-2 of the original ground are used. ,..., 50- (N-1), 50-N may be used to easily calculate the bearing capacity of the original ground using one of the average value, median value, and minimum value of the ground strength. .

  Thus, in this embodiment, the case where the structure was not built in the original ground was assumed, and the case where the ground constant of the original ground was acquired using the soil ground specimen was explained. However, as shown in FIG. 10 as an example, the estimation process described above is applied by using a soil specimen around the structure 60 even when the structure 60 is constructed immediately above the original ground. be able to.

  That is, when the structure 60 is constructed immediately above the original ground, it is expected that the ground strength of the original ground changes according to the weight of the structure 60 even in a state where no earthquake occurs. Is done. Therefore, any of stress, maximum stress, strain, maximum strain, energy, and maximum energy derived by one-dimensional seismic response analysis in the ground where no structure is constructed depends on the weight of the structure 60 on the original ground. Then, the amount corresponding to the weight is adjusted, and the corresponding relationship between the stress, maximum stress, strain, maximum strain, energy and maximum energy described above and the strength change rate, and the adjusted stress of the original ground, maximum The ground strength at the time of occurrence of the earthquake in the original ground is estimated using any one of stress, strain, maximum strain, energy and maximum energy and the inertial force converted from the acceleration obtained by the seismic response analysis. Alternatively, a one-dimensional seismic response analysis that considers only the weight of the structure is performed, and a correspondence relationship between any one of stress, maximum stress, strain, maximum strain, energy and maximum energy and the intensity change rate is obtained. The ground strength at the time of occurrence of the earthquake in the original ground may be estimated using the obtained correspondence and the inertia force converted from the acceleration obtained by the earthquake response analysis.

  In addition, when the structure 60 is constructed immediately above the original ground, the strength of the ground greatly changes in response to the weight of the structure 60 as the depth of the original ground decreases in a state where no earthquake has occurred. doing. Therefore, any of stress, maximum stress, strain, maximum strain, energy, and maximum energy derived by one-dimensional seismic response analysis in the ground where no structure is constructed depends on the weight of the structure 60 on the original ground. As the depth of the ground becomes shallower, the amount of adjustment is adjusted so that the amount of adjustment increases, and any one of the stress, maximum stress, strain, maximum strain, energy and maximum energy described above and the strength change rate At the time of the occurrence of an earthquake in the original ground, using any of the adjusted original ground stress, maximum stress, strain, maximum strain, energy and maximum energy and the inertial force converted from the acceleration obtained by the seismic response analysis The ground strength may be estimated.

[Example]
As shown in FIG. 11, by using the method of the present embodiment described above, the depth of a one-dimensional ground model (density 1.8 t / m ³ , S wave velocity Vs = 100 m / s) of the target ground to be analyzed. One-dimensional seismic response analysis was performed by inputting the target seismic motion to be analyzed into the lower part of the analysis mesh divided into 10 in the direction. Note that the seismic motion shown in FIG. 12 was used as the target seismic motion.

  As an analysis result of this seismic response analysis, FIG. 13 shows a graph representing the relationship between the depth of the ground [m] and the maximum shear strain of the ground [%]. In this analysis result, the maximum shear strain is shown as a ratio to the horizontal length of the analysis mesh. As can be seen from FIG. 13, the maximum shear strain increases as the ground depth increases.

Moreover, the ground strength after the earthquake of the target ground was estimated from the relationship between the depth of the ground [m] and the maximum shear strain [%] of the ground using the following equation (1). Note that the S _A in equation (1), a ground strength before the earthquake, S _B is the ground strength after the earthquake, epsilon is the maximum shear strain.

  In FIG. 14, the graph showing the relationship between the depth [m] of the ground and the estimation result of the ground strength after the earthquake of the target ground is shown. According to FIG. 14, the ground strength before the earthquake is constant regardless of the depth, but it can be seen that the ground strength after the earthquake becomes weaker as the depth of the ground becomes deeper.

  Based on the ground strength estimated in this way, a foundation of the structure is provided on the target ground using an analysis mesh of the target ground as shown in FIG. 15, and the load of the structure is applied to the target ground. The bearing capacity analysis was performed to calculate the bearing capacity of the target ground after the earthquake in the loaded state. In this embodiment, the foundation is directly based, but the foundation is a concept including a direct foundation (shallow ground improvement foundation, deep ground improvement foundation), a pile foundation, a combination foundation of a direct foundation and a pile foundation, and the like. .

  FIG. 16 shows the analysis results of the bearing capacity of the target ground after the earthquake when this bearing capacity analysis was performed. From this bearing capacity analysis, the bearing capacity of the target ground before the earthquake was 1573 [kPa], whereas the bearing capacity of the target ground after the earthquake was calculated to be 1314 [kPa].

  In the conventional method, the work of performing the seismic response analysis in the entire analysis area and then analyzing the bearing capacity has occurred, so the larger the analysis area or the longer the earthquake motion, It took time to analyze the seismic response. Although it is possible to shorten the analysis time by improving the processing speed of the computer, at the present stage, it is expected that it takes one day or more to calculate the bearing capacity.

  On the other hand, when the method of the present invention is used, the analysis area of the seismic response analysis can be made small, and although it is an analysis performed on the entire analysis area, the strength of the ground is estimated to analyze the bearing capacity. Therefore, the bearing capacity of the ground can be calculated in several hours (for example, 4 to 6 hours).

  Furthermore, it is needless to say that the present invention can be implemented in various modes without departing from the gist of the present invention.

10 Supporting force estimation device 14 CPU
20 Nonvolatile memory 30-1 to 30-M Strength change information 32 Ground ground constant information 34 Seismic waveform information 50 Original ground specimen 50-1 to 50-N Divided area 60 Structure

Claims (2)

Using test specimens collected from a plurality of grounds having different ground constants, the correspondence relationship between the stress of the ground, the maximum stress, the strain, the maximum strain, the energy and the maximum energy, and the strength change rate of the ground is the plurality of First deriving means for deriving for each ground;
A second method for deriving any one of stress, maximum stress, strain, maximum strain, energy, and maximum energy of the estimated target ground by inputting an assumed earthquake waveform using the ground constant of the estimated target ground and performing an earthquake response analysis Deriving means;
Using the correspondence relationship derived by the first deriving unit and any one of the stress, maximum stress, strain, maximum strain, energy, and maximum energy derived by the second deriving unit, the estimation target ground Estimating means for estimating the intensity when an earthquake having the earthquake waveform of
From the strength when the earthquake of the estimation target ground estimated by the estimation means, the calculation means for calculating the bearing capacity when the earthquake of the estimation target ground occurs,
A bearing capacity estimation device. The estimation means is obtained by an earthquake response analysis with any one of the stress, maximum stress, strain, maximum strain, energy, and maximum energy adjusted according to the correspondence and the weight of the structure on the estimation target ground. The bearing capacity estimation device according to claim 1, wherein the strength at the time of occurrence of the earthquake of the estimation target ground is estimated using an inertial force converted from the obtained acceleration.