KR20200077364A - Earthquake-Resistance Design System and Method of soil-pile system considering dynamic p-y curves - Google Patents

Abstract

The present invention relates to a seismic design system for a ground-pile system considering a dynamic characteristic, which comprises: an input value calculation part (100) for calculating input values of frequencies and acceleration for a plurality of ranges by the 1 g shaking table test; an initial dynamic p-y curve generation part (200) for generating an initial dynamic p-y curve in a range of the input frequencies and input acceleration obtained by the input value calculation part (100); a vertex search part (300) for finding out vertexes in which maximum subgrade reaction is observed from the initial dynamic p-y curve; and a final dynamic p-y curve deriving part (400) for connecting the searched vertexes to derive a final dynamic p-y curve which is applicable to an equivalent static analysis.

Description

Earthquake-Resistance Design System and Method of soil-pile system considering dynamic p-y curves}

The present invention relates to a seismic design method of a ground-pile system. Specifically, it relates to a seismic design method of a ground-pile system considering dynamic characteristics.

In recent years, the number of large-scale earthquakes and tsunamis over 6.0 has increased in many parts of the world, causing many people and property damage. In Korea, the frequency of earthquake occurrence has been increasing steadily since 1988, and in the past two years, an earthquake of magnitude 5.0 in the Ulsan area, an earthquake of magnitude 5.8 in the Gyeongju region, and an earthquake of magnitude 5.4 in the Pohang region.

Therefore, Korea is no longer a safe zone for earthquakes. Due to the deformation and damage of structures due to earthquakes, personal and property damage can occur, so the importance of seismic design is gradually increasing.

In the present invention, a lower foundation system when various types of cyclic loading and dynamic loading are applied through an indoor shaking table experiment and detailed analysis capable of simulating seismic loads suitable for domestic design standards. The purpose of this study is to grasp the dynamic behavior of and to present the characteristics of the ground reaction force coefficient. Through this, I would like to propose a seismic analysis and design technique that can economically and reasonably predict the dynamic behavior of a structure considering the interaction of the structure-base-ground.

The p-y curve method (ground reaction force-displacement curve method), which can take into account the nonlinearity of the ground, is widely used in pile foundation analysis of structures subjected to lateral monotonic loading. In the seismic design of pile foundations, the equivalent static analysis method is mainly used to analyze the inertial force acting on the pile by an earthquake load with an additional load.

In order to analyze the lateral behavior of piles under horizontal load during equivalent static analysis, a p-y curve method that can take into account the nonlinear behavior of the ground has been widely used. In the case of receiving a horizontal static load, an empirical p-y curve function is mainly used depending on the ground conditions.

However, for the condition of receiving a horizontal load that acts repeatedly, a generalized p-y curve model that can take into account the characteristics of the repeated load has not been proposed at home or abroad. In spite of the dynamic load conditions, the p-y curve in a static state is used as it is or a part of it is used.

Through the existing research cases, the difference in behavior between cyclic loading and dynamic loading can be seen for horizontal loads that act repeatedly.

It has been reported that cyclic loading reduces the resistance of the ground through conventional field loading tests. In addition, it has been reported that the effect of reducing ground resistance due to repeated loads is influenced by the number of load repetitions, the construction method of piles, and the size and shape of the repeated loads.

In the seismic design of pile foundations, an equivalent static analysis method is mainly used to analyze by applying an inertial force acting on the pile as an additional load, and during the equivalent static analysis, to analyze the lateral behavior of the pile under horizontal load, The py curve method, which can consider nonlinear behavior, is widely used.

The p-y curve was developed based on the experiment of loading a static or cyclic load on the pile head under various ground conditions. Most of the existing py curves are py curves that are experimentally calculated by applying static loads or repeated loads to the pile head. They are not suitable for dynamic load conditions where the influence of the ground around the pile must be considered as well as the inertia force at the top of the pile. .

To overcome this, studies are being conducted on p-y curves of piles considering dynamic load conditions. In the prior art, experiments were performed to apply vibration to the head of the pile, and it was confirmed that the sloping slope of the dynamic p-y curve greatly influences the load frequency.

(Document 1) Republic of Korea Patent Publication No. 10-2005-0112698 (2005.12.01)

The seismic design system and seismic design method of the ground-pile system considering the dynamic characteristics according to the present invention have the following problems.

First, the dynamic p-y curve influencing factor of the basic structure during an earthquake is proposed by analyzing the behavior considering the mutual influence of the structure-ground-pile.

Second, a reasonable dynamic p-y curve considering natural frequency and load frequency is proposed for the limited design method for equivalent static analysis used in the current design.

The problem of the present invention is not limited to those mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.

The present invention is a seismic design system of a ground-pile system in consideration of dynamic characteristics, an input value calculating unit 100 for calculating input values of frequencies and accelerations for a plurality of ranges by a 1g shaking table experiment; An initial dynamic p-y curve generator 200 for generating an initial dynamic p-y curve in the input frequency and input acceleration range obtained from the input value calculating unit 100; A vertex search unit (300) for finding vertices with maximum ground reaction force from the initial dynamic p-y curve; And a final dynamic p-y curve derivation unit 400 that derives a final dynamic p-y curve applicable to equivalent static analysis by connecting the searched vertices.

The input frequency calculating unit 110 according to the present invention may calculate the natural frequency fn of a specific condition through a sweep test, and calculate the input frequency at a ratio of 0.4fn to 1.6fn based on the natural frequency.

The input frequency calculating unit 110 according to the present invention may calculate the natural frequency fn of a specific condition through a sweep test, and calculate the input frequency at a ratio of 0.4fn to 1.6fn based on the natural frequency.

The input acceleration calculating unit 120 according to the present invention fixes the input frequency to 1.0f _n equal to the natural frequency, and then changes the input acceleration from 0.098g to 0.4g when the relative density (Dr) of the compact ground is 80%. When the relative density (Dr) of loose ground is 40%, the input acceleration can be changed from 0.098g to 0.3g.

The first dynamic py curve generator 200 according to the present invention determines the bending moment distribution function for each depth and then differentiates it twice according to Equation 1 to calculate the ground reaction force, and integrates it twice according to Equation 2 to displace the pile. Can be calculated.

In the present invention, the displacement (y) constituting the dynamic py curve is the relative displacement between the ground and the pile, and the integral accelerometer measurement value is integrated twice to calculate the free-field ground displacement, and the ground displacement is subtracted from the pile displacement to be dynamic You can create a py curve.

The final dynamic p-y curve derivation unit 400 according to the present invention may use Equation 3 to derive the final dynamic p-y curve.

The initial slope K according to the present invention may be determined by Equation (4).

The statistical constant (A) according to the present invention is calculated by linear regression analysis, is 1414.8 when the relative density of the dense ground is 80%, is provided as 995.94 when the relative density of the loose ground is 40%, and the initial slope (K ) The equation may be represented by Equation 5 and Equation 6 according to the relative density (Dr) of the ground.

The final dynamic p-y curve derivation unit 400 according to the present invention may use Equation (7) to derive the extreme ground reaction force (Pu) of the dynamic p-y curve.

In order to determine the statistical constants A and n according to the present invention, Equation 7 is modified to Equation 8 to perform a linear regression analysis on a log scale, and the ultimate ground reaction force (Pu) of the dynamic py curve is the relative of the ground. Depending on the density, it can be derived from Equation 9 and Equation 10.

The present invention is a seismic design method of a ground-pile system in consideration of dynamic characteristics, in which the input value calculating unit 100 calculates input values of frequency and acceleration for a plurality of ranges through a 1 g shaking table experiment;

The initial dynamic py curve generation unit 200 generates the initial dynamic py curve from the input frequency and input acceleration range obtained from the input value calculation unit 100, and the vertex search unit 300 is the maximum ground from the initial dynamic py curve Step S2 to find the vertices where the reaction force appears; And

The final dynamic p-y curve derivation unit 400 may include a step S3 of connecting the vertices searched to derive a final dynamic p-y curve applicable to equivalent static analysis.

The present invention is a computer program, preferably a computer program stored in a computer-readable recording medium in order to execute a seismic design method of a ground-pile system in consideration of dynamic characteristics according to the present invention in combination with hardware.

The seismic design system and seismic design method of the ground-pile system considering the dynamic characteristics according to the present invention have the following effects.

First, a rational seismic design is possible by using a dynamic p-y curve considering the integrated interaction of the ground-base.

Second, the existing proposals were results that did not take into account the natural frequency and the load frequency. However, in this technology, a dynamic p-y curve is proposed through consideration of the natural frequency and the load frequency, and there is a reasonable and economical design effect.

The effects of the present invention are not limited to those mentioned above, and other effects not mentioned will become apparent to those skilled in the art from the following description.

1 is a block diagram of a seismic design system of a ground-pile system according to the present invention.
2 is a flow chart of a seismic design method of a ground-pile system according to the present invention.
Figure 3 shows the static py curve of the pile acting horizontal load.
4 shows a dynamic py curve of a pile on which horizontal load is applied.
5 to 10 show a dynamic py central curve for each depth according to the present invention.
11 is a graph of determining the initial slope according to the present invention.
12 is a graph relating to the determination of a ground reaction force according to the present invention.
13 to 18 show a comparison of dynamic py curves according to depths according to the present invention.
FIG. 19 shows a comparison of pile displacement by depth for dense sandy soil, and FIG. 20 shows a comparison of pile displacement by depth for loose sandy soil.
21 shows a comparison of pile bending moments by depth for dense sandy soils, and FIG. 22 shows a comparison of pile bending moments by depth for loose sandy soils.
23 shows a comparison of pile shear force by depth for dense sandy soil, and FIG. 24 shows a comparison of pile shear force by depth for loose sandy soil.
25 shows the maximum displacement of the pile head by input frequency.
26 shows the natural frequency of the pile system for each input acceleration.
27 to 30 show dynamic py curves for each pile depth according to the input frequency.
31 is a py curve for each frequency.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings so that those skilled in the art to which the present invention pertains can easily practice. As those of ordinary skill in the art to which the present invention pertains can easily understand, the embodiments described below may be modified in various forms without departing from the concept and scope of the present invention. Where possible, the same or similar parts are indicated by the same reference numerals in the drawings.

The terminology used in this specification is only for referring to a specific embodiment, and is not intended to limit the present invention. The singular forms used herein also include plural forms unless the phrases clearly indicate the opposite.

As used herein, the meaning of “comprising” embodies certain properties, regions, integers, steps, actions, elements and/or components, and other specific properties, regions, integers, steps, actions, elements, components and/or It does not exclude the presence or addition of military forces.

All terms including technical terms and scientific terms used in the present specification have the same meaning as those generally understood by those skilled in the art to which the present invention pertains. Terms defined in the dictionary are additionally interpreted as having meanings consistent with related technical documents and currently disclosed contents, and are not interpreted in an ideal or very formal sense unless defined.

3 shows a static p-y curve of a pile acting on a horizontal load, and FIG. 4 shows a dynamic p-y curve of a pile acting on a horizontal load.

In the prior art, as shown in Figs. 3 and 4, the p-y curves for static and cyclic loads and dynamic loads differ significantly. This is already confirmed by many previous researchers. However, the current design is designed using the equivalent static analysis, and the existing research results do not consider the load frequency and the natural frequency of the ground-pile system.

However, the p-y curve of the pile under dynamic load is strongly influenced by the load frequency, and the influence on the load frequency is closely related to the natural frequency of the ground-pile system.

Therefore, in the present invention, a dynamic p-y curve is proposed considering the effects of load frequency and natural frequency of a pile under dynamic load.

Hereinafter, the present invention will be described with reference to the drawings.

1 is a block diagram of a seismic design system of a ground-pile system according to the present invention.

The seismic design system of the ground-pile system considering the dynamic characteristics according to the present invention includes an input value calculation unit 100, an initial dynamic py curve generation unit 200, a vertex search unit 300, and a final dynamic py curve derivation unit 400 ).

The input value calculating unit 100 according to the present invention can calculate the input values of frequency and acceleration for a plurality of ranges through a 1 g shaking table experiment.

The initial dynamic p-y curve generation unit 200 according to the present invention may generate the initial dynamic p-y curve from the input frequency and input acceleration range obtained from the input value calculation unit 100.

The vertex search unit 300 according to the present invention can find vertices where maximum ground reaction force appears from the initial dynamic p-y curve.

The final dynamic p-y curve derivation unit 400 according to the present invention may derive the final dynamic p-y curve applicable to equivalent static analysis by connecting the searched vertices.

The input value calculating unit 100 according to the present invention includes an input frequency calculating unit 110 for calculating the input frequency of the input load and an input acceleration calculating unit 120 considering the natural frequency of the pile system, and the load and ground It is possible to perform the 1 g shaking table experiment for each condition.

The input frequency calculator 110 may calculate the natural frequency fn of a specific condition through a sweep test, and calculate the input frequency at a ratio of 0.4fn to 1.6fn based on the natural frequency.

The input acceleration calculating unit 120 can fix the input frequency to 1.0f _n equal to the natural frequency, and then change the input acceleration from 0.098g to 0.4g when the relative density (Dr) of the compact ground is 80%. . When the relative density (Dr) of the loose ground is 40%, the input acceleration can be changed from 0.098g to 0.3g.

The first dynamic py curve generator 200 according to the present invention determines the bending moment distribution function for each depth and then differentiates it twice according to Equation 1 to calculate the ground reaction force, and integrates it twice according to Equation 2 below. The displacement of can be calculated.

Here, p is the ground reaction force, y is the displacement of the pile, z is the depth, EI is the bending stiffness of the pile, M (z) is the moment distribution function of the pile.

The displacement (y) constituting the dynamic py curve is the relative displacement between the ground and the pile, and the integral accelerometer measurement value is integrated twice to calculate the free-field ground displacement and subtract the ground displacement from the pile displacement to generate a dynamic py curve. Can.

The final dynamic p-y curve derivation unit 400 according to the present invention may use Equation 3 below to derive the final dynamic p-y curve.

Here, p is the horizontal resistance of the ground (kN/m), y is the horizontal displacement of the pile (m), K is the initial slope or ground reaction force coefficient (kN/m3), pu is the ultimate horizontal resistance of the ground (kN/m) Indicates.

In the present invention, the initial slope of the dynamic p-y curve and the ultimate ground reaction force are used as a function of restraint pressure and Rankine's manual earth pressure coefficient.

The initial slope K according to the present invention can be determined by the following equation (4).

Here, Pa represents atmospheric pressure (10.13 N/cm ² ), σ'represents restraint pressure, and A represents a statistical constant.

5 to 10 show a dynamic p-y central curve for each depth according to the present invention. It represents the maximum points of the dynamic p-y central curve obtained through regression analysis and the experimentally obtained dynamic p-y curve. Through this, it can be seen that the dynamic p-y central curve reflects the nonlinearity and experimental values of the ground-pile system well.

11 shows the initial slope for each depth obtained from the experimental results. A linear regression analysis was performed to determine the statistical constant A. When the relative density is 80%, A is 1414.8, and when the relative density is 40%, A is 995.94.

In the present invention, the statistical constant (A) is calculated by linear regression analysis, is 1414.8 when the relative density of the dense ground is 80%, is provided as 995.94 when the relative density of the loose ground is 40%, and the initial slope ( K) Equation may be represented by the following Equations 5 and 6 according to the relative density (Dr) of the ground.

The final dynamic p-y curve derivation unit 400 according to the present invention may use the following equation (7) to derive the extreme ground reaction force (Pu) of the dynamic p-y curve.

Here, D is the pile diameter (cm), Pu/D is the ultimate ground reaction force per unit width (N/cm ² ), K _P is the passive soil pressure coefficient of Rankine, r'is the effective unit weight (N/cm ³ ), z is Depth (cm), A and n represent statistical constants.

In order to determine the statistical constants A and n, Equation 7 is transformed to Equation 8 below to perform a linear regression analysis on a log scale.

The extreme ground reaction force (Pu) of the dynamic p-y curve may be derived by the following Equations 9 and 10 according to the relative density of the ground.

12 is a graph relating to the determination of a ground reaction force according to the present invention.

Meanwhile, FIGS. 13 to 18 show a comparison of dynamic p-y curves according to depths according to the present invention. That is, it shows the result of comparing the existing p-y curve with the proposed p-y curve with respect to the experimental results.

The existing py curve used for comparison was the py curve proposed by API (1987) and Reese et al. (1974). The internal friction angle and ground reaction force required for the analysis were the values recommended by API (1987). For loose sandy soils, 30 ^o is used, and for dense sandy soils, 40 ^o is used. In addition, a ground reaction factor of 74,134 kPa/m for dense sand and 11,948 kPa/m for loose sand is used.

13 to 18, it can be seen that the existing p-y curve predicts the ultimate ground reaction force smaller than the experimental results. On the contrary, it can be seen that the proposed p-y curve is predicted relatively well.

19 shows a comparison of pile displacement by depth for dense sandy soil, and FIG. 20 shows a comparison of pile displacement by depth for loose sandy soil. That is, it shows the experimental results and the predicted values of p-y curves in dense and loose sandy soils. Through this, the API and the Reese equation overestimate the pile displacement, but it can be seen that the p-y curve equation according to the present invention is in good agreement with the experimental results.

21 shows a comparison of pile bending moments by depth for dense sandy soils, and FIG. 22 shows a comparison of pile bending moments by depth for loose sandy soils. 23 shows a comparison of pile shear force by depth for dense sandy soil, and FIG. 24 illustrates a comparison of pile shear force by depth for loose sandy soil. That is, it shows the bending moment and shear force distribution by depth of pile in dense and loose sand.

In both cases, we can confirm that the proposed p-y curve predicts the experimental results relatively well. However, the p-y curves of API and Reese were found to predict smaller bending moments and shear forces than the experimental results. This means that a small shear force and bending moment are sufficient to generate the maximum displacement measured experimentally. In other words, API and Reese's p-y curve means that the bending moment and shear force are conservatively predicted.

Meanwhile, the present invention can be implemented by a seismic design method of a ground-pile system considering dynamic characteristics. The technical structure common to the above-described seismic design system, in particular, equations, etc., is intended to describe this seismic design system while minimizing overlapping materials.

The seismic design method according to the present invention includes the step S1 in which the input value calculating unit 100 calculates the input values of frequency and acceleration for a plurality of ranges through a 1 g shaking table experiment; The initial dynamic py curve generation unit 200 generates the initial dynamic py curve from the input frequency and input acceleration range obtained from the input value calculation unit 100, and the vertex search unit 300 is the maximum ground from the initial dynamic py curve Step S2 to find the vertices where the reaction force appears; And

And a step S3 in which the final dynamic p-y curve derivation unit 400 connects the discovered vertices to derive a final dynamic p-y curve applicable to equivalent static analysis.

The input value calculating unit 100 in step S1 includes an input frequency calculating unit 110 for calculating the input frequency of the input load and an input acceleration calculating unit 120 considering the natural frequency of the pile system, and the load and ground conditions. Star 1g shaking table experiment can be performed.

The input frequency estimator 110 of step S1 may calculate the natural frequency fn of a specific condition through a sweep test, and calculate the input frequency at a ratio of 0.4fn to 1.6fn based on the natural frequency.

The input acceleration calculating unit 120 in step S1 fixes the input frequency to 1.0f _n equal to the natural frequency, and then changes the input acceleration from 0.098g to 0.4g when the relative density (Dr) of the compact ground is 80%. When the relative density (Dr) of the loose ground is 40%, the input acceleration can be changed from 0.098g to 0.3g.

The initial dynamic py curve generator 200 of step S2 determines the ground reaction force by differentiating it twice according to Equation 1 after determining the bending moment distribution function for each depth, and integrating it twice according to Equation 2 to calculate the displacement of the pile. Can be calculated.

The final dynamic p-y curve derivation unit 400 of step S2 may use Equation 3 to derive the final dynamic p-y curve.

The initial slope K may be determined by Equation (4).

The statistical constant (A) is calculated by linear regression analysis, 1414.8 when the relative density of the compact ground is 80%, and 995.94 when the relative density of the loose ground is 40%, and the initial slope (K) formula is According to the relative density (Dr), it may be represented by Equation (5) and Equation (6).

The final dynamic p-y curve derivation unit 400 may use the following equation (7) to derive the extreme ground reaction force (Pu) of the dynamic p-y curve.

In addition, by transforming Equation 7 into Equation 8, linear regression analysis is performed on a log scale, and the ultimate ground reaction force (Pu) of the dynamic py curve is derived by Equation 9 and Equation 10 according to the relative density of the ground. Can be.

Meanwhile, the present invention may be implemented as a computer program. The present invention is preferably a computer program stored in a computer-readable recording medium in order to execute a seismic design method of a ground-pile system in consideration of dynamic characteristics according to the present invention in combination with hardware.

Hereinafter, the present invention will be described in more detail while performing an actual experiment.

Experiment method and test conditions

The pile was fixed to a 9 cm high aluminum plate for the effect of entering the rock, and the aluminum plate was bolted to the tojo bottom plate to prevent movement during vibration.

The ground was formed at a height of 70 cm and a sample was prepared using vibration compaction. For compact ground, vibration compaction was performed every 15 cm in height to create a relative density of 80%, and for loose ground, vibration compaction was performed after the final sample composition to construct a relative density of 40%. After filling the soil up to the planned height, finish the ground construction by spreading it evenly using a wide brush so that it becomes a horizontal ground.

After installing the pile cap and the upper load on the top of the pile, an accelerometer was attached, and LVDT was installed on both ends of the pile cap.

Selection criteria for various frequency and acceleration ranges

As a seismic load, a sine wave, a sinusoidal wave, was used for 5 seconds for each condition. The size of the load was varied from 0.098g to 0.4g, including level 1 and special grade collapse prevention levels. In addition, experiments were performed by varying the input frequency as real seismic waves have various frequency components. In order to determine the frequency of the input load, that is, the input seismic wave, the natural frequency of each condition was calculated through a sweep test, and the input frequency was calculated at a ratio of 0.4f _n to 1.6f _n based on the natural frequency.

Input frequency

Analyze the dynamic behavior of the basic structure of the marine jacket according to the input frequency. To this end, experiments were performed while changing the input frequency under conditions of 0.22 g of input acceleration and 80% of relative density.

First, a sweep test was performed to calculate the input frequency, and based on this, an experiment was performed with an input frequency ranging from 0.4f _n to 1.6f _n (f _n = natural frequency).

25 shows the maximum displacement of the pile head by input frequency, and it can be seen that it greatly influences the behavior of the pile by input frequency.

Input acceleration

We analyze the dynamic behavior of the basic structure of the marine jacket according to the input acceleration. To this end, the input frequency was fixed at 1.0f _n equal to the natural frequency under conditions of 40% and 80% relative density.

The experiment is performed by changing the input acceleration from 0.098g to 0.4g when the relative density is 80% and from 0.098g to 0.3g when the relative density is 40%. If the input acceleration is greater than this, the ground settlement will occur simultaneously with the vibration, thus limiting the input acceleration.

Figure 26 shows the natural frequency of the pile system by acceleration and relative density through the sweep test (sweep test). It can be seen that the higher the input acceleration, the smaller the natural frequency of the pile system, and the higher the relative density, the larger the natural frequency.

This is judged to be because the stiffness of the pile is relatively small due to an increase in the input load or an increase in the relative density.

The dynamic p-y hysteresis curve can be calculated based on the bending moment measured for each pile depth based on the simple beam theory. First, after determining the bending moment distribution function for each depth, the ground reaction force was calculated by differentiating twice as in Equation 1, and the displacement of the pile was calculated by integrating twice as in Equation 2.

How to create a dynamic p-y curve for piles

For each 0.001 second time interval in which the data was measured, the moment distribution function for each depth of the pile was determined, and the ground reaction force and displacement were calculated according to general beam theory such as Equation 1 and Equation 2. In the graph, a dynamic py curve was created.

The moment distribution function according to the pile depth is determined from the measured strain gauge, and the ground reaction force p is obtained by differentiating the moment curve twice, and the pile displacement y is obtained by integrating the moment curve twice. The function of the moment distribution curve is obtained by applying the cubic spline fitting method.

는 지반-말뚝 간 상대변위를 의미하므로, 지반 가속도계 계측 값을 2번 적분하여 자유장 지반변위를 산정하고, 말뚝 변위에서 지반 변위를 빼줌으로써 최종적으로 동적 p-y곡선을 작성하였다.Displacements that make up the dynamic py curve

Since is the relative displacement between the ground and the pile, the free field ground displacement was calculated by integrating the measurement value of the ground accelerometer twice, and the dynamic displacement curve was finally created by subtracting the ground displacement from the pile displacement.

27 to 30 show dynamic p-y curves for each pile depth according to the input frequency. It can be seen that the displacement of the pile increases as the intrinsic frequency approaches, and it can be seen that the dip slope of the dynamic p-y curve decreases.

31 is a p-y curve for each frequency. In FIG. 31, the maximum points are extracted from the p-y curves for each frequency, and the ground reaction force and pile displacement are shown in one graph as shown in FIGS.

After finding the vertices that show the maximum ground reaction force from the dynamic p-y curves of various frequency and acceleration ranges obtained through the 1g shaking table experiment, connect all these points to derive a dynamic p-y curve that can be applied to the equivalent static analysis.

In order to calculate the dynamic p-y curve equation, the skeleton of the empirical equation is determined by the hyperbolic function shown in equation (3).

In the present invention, we propose a function of the initial slope of the dynamic p-y curve and the extreme ground reaction force using the restraint pressure and Rankine's manual earth pressure coefficient.

The initial slope (K) of the dynamic p-y curve is expressed by an empirical equation such as Equation (4).

5 to 10 show the maximum points of the dynamic p-y central curve obtained through regression analysis and the experimentally obtained dynamic p-y curve. Through this, it can be seen that the dynamic p-y central curve reflects the nonlinearity and experimental values of the ground-pile system well.

11 shows the initial slope for each depth obtained from the experimental results. A linear regression analysis was performed to determine the statistical constant A. When the relative density is 80%, A is 1414.8, and when the relative density is 40%, A is 995.94.

Finally, the equations of the initial slope are proposed as Equations 5 and 6 according to the relative density.

Equation 7 related to passive earth pressure was used to propose the extreme ground reaction force (Pa) of the dynamic p-y curve.

In order to determine the statistical constants A and n, Equation 7 was modified as Equation 8 to perform a linear regression analysis on a log scale. 12 shows a graph for linear regression analysis. Through this, finally, the empirical expression for the extreme ground reaction force is proposed according to the relative density as in Equation 9 and Equation 10.

The embodiments described in the present specification and the accompanying drawings are merely illustrative of some of the technical spirit included in the present invention. Therefore, the embodiments disclosed in the present specification are not intended to limit the technical spirit of the present invention, but to explain the present invention, it is obvious that the scope of the technical spirit of the present invention is not limited by these embodiments. Within the scope of the technical spirit included in the specification and drawings of the present invention, modifications and specific embodiments that can be easily inferred by those skilled in the art should be interpreted as being included in the scope of the present invention.

100: input value calculation
110: Input frequency calculation
120: input acceleration calculation
200: first dynamic py curve generator
300: vertex search unit
400: Final dynamic py curve derivation unit

Claims (22)

An input value calculating unit 100 for calculating input values of frequency and acceleration for a plurality of ranges by a 1 g shaking table experiment;
An initial dynamic py curve generator 200 for generating an initial dynamic py curve in the input frequency and input acceleration ranges obtained from the input value calculating unit 100;
A vertex search unit (300) for finding vertices with maximum ground reaction force from the initial dynamic py curve; And
Seismic design system of a ground-pile system considering dynamic characteristics, comprising a final dynamic py curve derivation unit 400 that derives a final dynamic py curve applicable to equivalent static analysis by connecting the searched vertices . The method according to claim 1,
The input value calculating unit 100 includes an input frequency calculating unit 110 for calculating the input frequency of the input load, and an input acceleration calculating unit 120 considering the natural frequency of the pile system, and a 1 g vibration table for each load and ground condition. Seismic design system of a ground-pile system considering dynamic characteristics characterized by performing an experiment. The method according to claim 2, wherein the input frequency calculation unit 110
Seismic design system of the ground-pile system considering dynamic characteristics characterized by calculating the natural frequency (fn) of a specific condition through a sweep test and calculating the input frequency at a ratio of 0.4fn to 1.6fn based on the natural frequency . The method according to claim 2, wherein the input acceleration calculation unit 120
After fixing the input frequency to 1.0f _n equal to the natural frequency, when the relative density (Dr) of the compact ground is 80%, change the input acceleration from 0.098g to 0.4g,
When the relative density (Dr) of the loose ground is 40%, the seismic design system of the ground-pile system considering dynamic characteristics characterized by changing the input acceleration from 0.098g to 0.3g. The method according to claim 1,
The first dynamic py curve generator 200 is
After determining the bending moment distribution function for each depth, the ground reaction force is calculated by differentiating it twice according to the following equation (1), and by integrating twice according to the following equation (2) to calculate the displacement of the pile. -Seismic design system of pile system.
[Equation 1]

[Equation 2]

(Where p is the ground reaction force, y is the displacement of the pile, z is the depth, EI is the bending stiffness of the pile, and M(z) represents the moment distribution function of the pile) The method according to claim 5,
The displacement (y) constituting the dynamic py curve is the relative displacement between the ground and the pile,
A seismic design system for a soil-pile system considering dynamic characteristics characterized by generating a dynamic py curve by calculating the free-field ground displacement by integrating the measured value of the ground accelerometer twice, and subtracting the ground displacement from the pile displacement. The method according to claim 1,
The final dynamic py curve derivation unit 400
To derive the final dynamic py curve, a seismic design system of a ground-pile system considering dynamic characteristics, characterized by using the following equation (3).
[Equation 3]

(Here, p is the horizontal resistance of the ground (kN/m), y is the horizontal displacement of the pile (m), K is the initial slope or ground reaction coefficient (kN/m3), pu is the ultimate horizontal resistance of the ground (kN/m) )) The method according to claim 10,
The initial slope (K) is a seismic design system of a ground-pile system considering dynamic characteristics, which is determined by the following equation (4).
[Equation 4]

(Here, Pa is atmospheric pressure (10.13 N/cm ² ), σ'is restraint pressure, and A is a statistical constant) The method according to claim 8,
The statistical constant (A) is calculated by linear regression analysis, 1414.8 when the relative density of the dense ground is 80%, and 995.94 when the relative density of the loose ground is 40%,
The initial slope (K) is a seismic design system of a soil-pile system considering dynamic characteristics, characterized in that it is represented by the following equations 5 and 6 according to the relative density (Dr) of the ground.
[Equation 5]

(Dense ground, relative density 80%)
[Equation 6]

(Loose ground, relative density 40%) The method according to claim 1,
The final dynamic py curve derivation unit 400
In order to derive the extreme ground reaction force (Pu) of the dynamic py curve, a seismic design system for a soil-pile system considering dynamic characteristics, characterized by using the following Equation (7).
[Equation 7]

(Where D is the pile diameter (cm), Pu/D is the ultimate ground reaction force per unit width (N/cm ² ), K _P is the Rankine's passive earth pressure coefficient, r'is the effective unit weight (N/cm ³ ), z Is depth (cm), A and n represent statistical constants) The method according to claim 10,
In order to determine the statistical constants A and n, the equation 7 is transformed into the following equation 8 to perform a linear regression analysis on a log scale,
The seismic design system of the ground-pile system considering dynamic characteristics, wherein the extreme ground reaction force (Pu) of the dynamic py curve is derived by Equation (9) and (10) according to the relative density of the ground.
[Equation 8]

[Equation 9]

(Dense ground, relative density 80%)
[Equation 10]

(Loose ground, relative density 40%) Step S1 in which the input value calculating unit 100 calculates input values of frequency and acceleration for a plurality of ranges by 1 g shaking table experiment;
The initial dynamic py curve generation unit 200 generates the initial dynamic py curve from the input frequency and input acceleration range obtained from the input value calculation unit 100, and the vertex search unit 300 is the maximum ground from the initial dynamic py curve Step S2 to find the vertices where the reaction force appears; And
And a step S3 of deriving a final dynamic py curve that can be applied to equivalent static analysis by connecting the vertices where the final dynamic py curve derivation unit 400 is searched for of the ground-pile system considering dynamic characteristics. Seismic design method. The method according to claim 12,
The input value calculating unit 100 in step S1 includes an input frequency calculating unit 110 for calculating the input frequency of the input load and an input acceleration calculating unit 120 considering the natural frequency of the pile system, and the load and ground conditions. A seismic design method for a ground-pile system considering dynamic characteristics, characterized by performing a 1g shaking table experiment. The method according to claim 13, wherein the input frequency calculation unit 110 of step S1
Seismic design method of ground-pile system considering dynamic characteristics characterized by calculating the natural frequency (fn) of a specific condition through a sweep test and calculating the input frequency at a ratio of 0.4fn to 1.6fn based on the natural frequency . The method according to claim 14, wherein the input acceleration calculation of step S1 120
After fixing the input frequency to 1.0f _n equal to the natural frequency, when the relative density (Dr) of the compact ground is 80%, change the input acceleration from 0.098g to 0.4g,
When the relative density (Dr) of the loose ground is 40%, the seismic design method of the ground-pile system considering the dynamic characteristics characterized by changing the input acceleration from 0.098g to 0.3g. The method according to claim 12, The initial dynamic py curve generation unit 200 of step S2 is
After determining the bending moment distribution function for each depth, the ground reaction force is calculated by differentiating it twice according to the following equation (1), and by integrating twice according to the following equation (2) to calculate the displacement of the pile. -Seismic design method of pile system.
[Equation 1]

[Equation 2]

(Where p is the ground reaction force, y is the displacement of the pile, z is the depth, EI is the bending stiffness of the pile, and M(z) represents the moment distribution function of the pile) The method according to claim 12, wherein the final dynamic py curve derivation unit 400 of step S2 is
In order to derive the final dynamic py curve, a seismic design method of a ground-pile system considering dynamic characteristics characterized by using Equation 3 below.
[Equation 3]

(Here, p is the horizontal resistance of the ground (kN/m), y is the horizontal displacement of the pile (m), K is the initial slope or ground reaction coefficient (kN/m3), pu is the ultimate horizontal resistance of the ground (kN/m) )) The method according to claim 17,
The initial slope (K) is a seismic design method of a ground-pile system considering dynamic characteristics, which is determined by the following equation (4).
[Equation 4]

(Here, Pa is atmospheric pressure (10.13 N/cm ² ), σ'is restraint pressure, and A is a statistical constant) The method according to claim 12,
The statistical constant (A) is calculated by linear regression analysis, 1414.8 when the relative density of the dense ground is 80%, and 995.94 when the relative density of the loose ground is 40%,
The initial slope (K) is a seismic design method of a ground-pile system considering dynamic characteristics, characterized in that it is represented by the following Equations 5 and 6 according to the relative density (Dr) of the ground.
[Equation 5]

(Dense ground, relative density 80%)
[Equation 6]

(Loose ground, relative density 40%) The method according to claim 12,
The final dynamic py curve derivation unit 400
To derive the extreme ground reaction force (Pu) of a dynamic py curve, a seismic design method of a soil-pile system considering dynamic characteristics, characterized by using the following equation (7).
[Equation 7]

(Where D is the pile diameter (cm), Pu/D is the ultimate ground reaction force per unit width (N/cm ² ), K _P is the Rankine's passive earth pressure coefficient, r'is the effective unit weight (N/cm ³ ), z Is depth (cm), A and n represent statistical constants) The method according to claim 20,
In order to determine the statistical constants A and n, the equation 7 is transformed into the following equation 8 to perform a linear regression analysis on a log scale,
The method of seismic design of a ground-pile system considering dynamic characteristics, wherein the extreme ground reaction force (Pu) of the dynamic py curve is derived by Equation (9) and (10) according to the relative density of the ground.
[Equation 8]

[Equation 9]

(Dense ground, relative density 80%)
[Equation 10]

(Loose ground, relative density 40%) A computer program stored in a computer-readable recording medium to execute a seismic design method of a ground-pile system in consideration of dynamic characteristics according to any one of claims 12 to 21 in combination with hardware.

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