JPH0328410A - Estimation of support layer for pile in pile embedding - Google Patents

Abstract

PURPOSE:To calculate an estimated support layer for a pile by obtaining a ratio of the sum of products of measured value of oil pressure or ammeter in every excavating section multiplied by an excavating time to the sum of N values to calculate the ratio as an estimated value for the N value in each section. CONSTITUTION:The sum of value N of every required section SIGMAN in a histogram of soil nature and the sum of product SIGMAa.b of measured value (a) of an ammeter of every predetermined excavating section in the excavation of foundation by an auger 1 multiplied by excavating time b are assured to be approximately in the correlation to each other. Then, a support layer N' estimated from the product value in each section is found to approximate the sum ratio alpha=SIGMAN/SIGMAa.b and calculated as the estimated value N'=alpha.a.b. Thus, the calculation Ra'=f(N') of an actual support force for a pile and the estimation of the support layer can be achieved, in the correlation of N value and measured value of the ammeter or oil pressure gauge.

Description

[Detailed description of the invention] "Field of industrial application" This invention relates to a method for estimating the support layer of a pile in an embedded pile construction method. "Prior art and problems to be solved by the invention" The bearing capacity of piles in the embedded pile method is required to be estimated using a bearing capacity calculation formula determined by a soil survey (poling survey), and the bearing capacity is confirmed based on this calculation formula. In such a bearing capacity estimation method, since it is carried out only on a part of the site, it is generally unclear whether or not the pile tip has actually been buried in the required N value part obtained by the standard penetration test. In order to estimate the hardness of the ground, are there any work guidelines such as checking the soil in the auger head or referring to the measured value of the auger motor's ammeter to estimate the hardness of the ground? There have been various proposals regarding the correlation between As a result of stacking, the cumulative N value ΣN for each required section obtained in the standard penetration test and the drive current of the electric motor of the auger or the drive oil pressure of the hydraulic motor of the auger for each predetermined excavation section when excavating with the auger are measured. Value (a) and drilling time (b)
There is a correlation with the cumulative product Σa-b, and the estimated value N° for the N value estimated from the product value of each interval is the cumulative ratio α=
By finding an approximation to the value determined by ΣN/Σa-b and calculating the estimated value for N in each section as N' = α・a-b, we can calculate the relationship between the N value and the measured value of the ammeter or oil pressure gauge. This paper proposes a method for estimating the bearing layer in the embedded pile method, which makes it possible to estimate the actual bearing layer of the pile through correlation. "Embodiments" Below, embodiments of the present invention shown in the drawings will be described.
According to many experiments conducted by the present inventors, the required section (
For example, the cumulative total of N values ΣN for each lm), the ammeter measurement value (a) and the excavation time (b ) and the cumulative total of products Σa-b are found to be almost correlated. As a result, we saw that the pile support layer N'' estimated from each interval product value approximates the cumulative ratio α = ΣN/Σa-b of the cumulative total ΣN of the above N values and the cumulative total Σa-b, The estimated value for N in each section is calculated as N' = α・a−b, and the N value and the current meter during actual auger excavation (
The actual pile bearing capacity lRa' =
It is now possible to estimate f(N') and its support base. Therefore, the above N values, a, and b values are input into a computing device 2 such as a computer, and the cumulative total ΣN, cumulative total Σa-b, and their cumulative ratio α=ΣN/Σa・b are calculated, and the standard penetration of each section is calculated. It is possible to calculate the estimated value N' = α·a−b for the test value N and to print it out in a graph as shown in FIG. "Effects of the Invention" As described above, according to the present invention, in the correlation between the N value obtained in the standard penetration test and the measured value of the ammeter or oil pressure gauge of the auger motor during actual pile embedding construction, By determining the estimated value N° of the bearing layer, it is possible to calculate the estimated bearing layer of the pile based on this.

[Brief explanation of drawings]

The fiSl diagram is a soil columnar diagram obtained in a standard penetration test. Figure 2 is a diagram showing the product of the measured value of an ammeter and the excavation time for each predetermined excavation section during excavation with an auger, and Figure 3 is a diagram showing the product of the excavation time. 1 is a perspective view showing an overview of computing equipment used in the l... Saiichigar, 2... Arithmetic unit.

Claims (1)

[Claims] 1) Cumulative sum Σ of the product of oil pressure or ammeter measurement value (a) and excavation time (b) for each predetermined excavation section during excavation by an auger
a and b, and the N obtained in the standard penetration test for each excavation section in the earlier period.
Find the mutual cumulative ratio α=ΣN/Σa・b with the cumulative total ΣN of the values, and calculate the estimated value N'=α・a・b for the N value in each section.
A method for estimating the support layer of a pile in an embedded pile construction method, which is characterized by calculating as follows.