JPH10153497A - Foundation pile bearing power evaluation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a foundation pile bearing power evaluation system by which the bearing power can be estimated with high accuracy by a hydraulic vibration exciter which can be comparatively easily transported. SOLUTION: The circumferential face frictional resistance and the point resistance of a pipe are inversely analytically identified by utilizing the data obtained from a loading test device using a hydraulic vibration exciter, and the data on elastic wave of every layers obtained from an underground sensor 5, and the bearing power at the static loading, is estimated on the basis of the result of the identification. Further in the inverse analyzation, the accuracy in identification is improved by applying the filtering method such as a Kalman filter or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a foundation pile supporting force evaluation system, and is particularly useful for simply and accurately evaluating the foundation pile supporting force.

[0002]

2. Description of the Related Art As a load test method for evaluating the bearing capacity of a foundation pile, a static load test method shown in FIG. 2, a dynamic load test method shown in FIG. 3, and a rapid load test method shown in FIG. 4 are known. ing.

In the static loading test method, as shown in FIG. 2, a reaction force pile 9 is cast around a foundation pile 1 to be tested, and a reaction force pile loading frame is assembled and a hydraulic jack 8 is used. A load test is performed to evaluate the bearing capacity. In the dynamic loading test method, as shown in FIG. 3, a cushion block 11 is installed on a foundation pile 1 to be tested, a hammer 10 is dropped thereon, and the acceleration of the hammer 10 at the time of impact is used. The bearing capacity is estimated by the wave theory analysis of the foundation pile 1. In the rapid loading test method, as shown in FIG. 4, a reaction body 12 is exploded by explosives, and the impact reaction force is applied to the foundation pile 1.
This is a test method to be loaded on the pile head. At the time of loading, the pile head displacement is measured by a laser, and the loading load is measured by the load cell 1.
3, and the supporting force is estimated using the one-dimensional wave theory based on the measured data.

[0004]

Of the three types of loading tests described above, the static loading test method is currently the most reliable, but the loading equipment is large and the time and cost required for one test are considerable. Cost. The dynamic loading test method requires analysis based on wave theory, and the information obtained from the pile head is limited.
Estimates of static bearing capacity vary considerably. It is said that the rapid loading test method can relatively express the static behavior of the pile at the design load level.However, the explosive is exploded and the impact reaction force is loaded on the pile head. Is severely restricted due to environmental problems such as vibration and noise, and it takes time to transport the loading device. In addition, as in the case of the dynamic loading test method, it is necessary to analytically evaluate the static bearing capacity, and at present, the estimation accuracy is still insufficient.

In view of the above prior art, an object of the present invention is to provide a foundation pile supporting force evaluation system capable of accurately estimating a supporting force using a hydraulic exciter which is relatively easy to carry.

[0006]

According to the structure of the present invention, which achieves the above object, a hydraulic exciter is mounted on a pile head of a foundation pile and an elastic wave is generated by striking the hydraulic exciter to generate an elastic wave. And the elastic wave data obtained from the pre-drilled measurement holes, using an analytical model such as the one-dimensional wave theory or the finite element method to estimate the bearing capacity of the foundation pile by inverse analysis. Features.

[0007]

Embodiments of the present invention will be described below in detail with reference to the drawings. The present embodiment is a case where the bearing capacity of a foundation pile is evaluated.

As shown in FIG. 1, the hydraulic exciter 2 is configured to strike the head of the foundation pile 1. Here, when the input pulse width is small, the damping material 3 such as a vibration-proof rubber is mounted on the pile head and hit. In addition, a measurement hole 4 is bored in the vertical direction near the foundation pile 1 and a sensor 5 which is an accelerometer is installed so as to be in close contact with the hole wall of the measurement hole 4. It is configured to receive waves. . Thus, the sensor 5
Based on the data obtained in the above, an analytical model based on the one-dimensional wave theory, in which the surface characteristics are changed for each layer based on the ground information obtained when drilling in advance, was created, and the Identify surface friction characteristics and tip characteristics by inverse analysis.

At this time, the data obtained through the sensor 5 is obtained through the ground, and the S / N ratio is poor, so that it is difficult to perform the reverse analysis as it is. Therefore, a filtering technique such as a Kalman filter is applied to improve identification accuracy, and a static bearing force characteristic is estimated based on the result.
Such processing is performed by the measurement system 6 and the data evaluation system 7
Do with.

According to the present embodiment as described above, since the loading is performed by the hydraulic vibration device 2, the control of the load level and the pulse width is easy, and the degree of freedom in the loading direction is large. In addition, since the characteristics between the pile and the ground for each layer can be accurately estimated using the data obtained from the sensor 5 embedded in the ground, the accuracy of static support force evaluation is improved.

[0011]

As described in detail with the above embodiment, according to the present invention, the input load can be controlled by the hydraulic exciter which is relatively easy to carry, so that an appropriate load can be set. is there. In addition, since the reverse analysis is performed using the ground data around the pile compared with the method of evaluating using only the elastic wave data of the normal pile head, it is possible to accurately identify the pile surface friction characteristics and tip resistance. is there.

[Brief description of the drawings]

FIG. 1 is an explanatory view conceptually showing a foundation pile supporting force evaluation system according to an embodiment of the present invention.

FIG. 2 is an explanatory view conceptually showing a static load test method which is a conventional method.

FIG. 3 is an explanatory view conceptually showing a conventional dynamic load test method.

FIG. 4 is an explanatory view conceptually showing a conventional rapid load test method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Foundation pile 2 Hydraulic excitation device 3 Damping material 4 Measurement hole 5 Sensor 6 Measurement system 7 Data evaluation system

Claims (1)

[Claims] A hydraulic exciter is mounted on a pile head of a foundation pile,
By hitting this, an elastic wave is generated, and based on the response of the pile head and the elastic wave data obtained from the pre-drilled measurement hole, an inverse analysis is performed using an analytical model such as the one-dimensional wave theory or the finite element method. A bearing capacity evaluation system for foundation piles, which is configured to estimate the bearing capacity of foundation piles.