Buried support pillar for suppressing vertical movement and buried construction method

Abstract

To provide a buried support pillar for suppressing vertical movement having a vertical movement suppression pipe 1 that suppresses vertical movement caused by linear expansion of a material accompanying the range of soil temperature fluctuation and air temperature fluctuation to a required value when measuring the amount of land surface subsidence, groundwater level, etc., and a buried construction method in which a metal pipe 2 supporting the support pillar is completely isolated from earth pressure caused by compression and swelling of soft ground 9 by a protective pipe 3.SOLUTION: In a buried support pillar for suppressing vertical movement, a metal pipe 2 having vertical strength and rigidity is covered with a vertical movement suppression pipe 1 having an extremely small linear expansion coefficient compared to the metal pipe 2, and is connected to the inside of the metal pipe, and a bottom of the vertical movement suppression pipe 1 is fixed to the metal pipe 2 by a support pipe 4 at a burial depth 11 where the ground temperature fluctuation range is reduced to a required value. When an excavation device 5 at a tip of the metal pipe 2 penetrates and fixes it in the hard ground 10, the metal pipe 2 passes through a durable protective pipe 3 that has been buried in advance, but the protective pipe 3 is buried by pressing it against the hard ground 10 without lifting its bottom surface, in order to insulate the metal pipe 2 from the earth pressure of the soft ground 9 without any gaps.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a buried support pillar that suppresses vertical movement, which suppresses both the linear expansion of materials caused by fluctuations in air and ground temperatures, and the vertical movement caused by earth pressure caused by the compression and swelling of soft ground. [Background technology]

[0002] When measuring the amount of ground surface subsidence, a drilling device is generally attached to the tip of a metal pipe that has vertical strength and rigidity, and is passed through a resin pipe that has been buried in soft ground beforehand to reach the hard ground that serves as the supporting layer, and penetrates the ground using rotational and pushing forces. Conventionally, the metal pipe fixed in this way was considered to be an immovable axis, and the relative movement between the metal pipe and the ground surface was detected by a sensor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Real whole Showa 61-50122 Summary of the Invention [Problem to be solved by the invention]

[0004] In Patent Document 1, the inner pipe 21 (corresponding to a metal pipe) is an immovable shaft with its bottom fixed to the hard ground, and the middle pipe 22 (corresponding to a resin pipe) is a pipe that sinks together with the soft ground while isolating the inner pipe 21 from the earth pressure of the soft ground. This prior art measures the amount of ground surface subsidence by detecting the vertical relative movement between the sinking middle pipe 22 and the inner pipe 21, which is an immovable shaft. However, this prior art has the following problems. First, the inner pipe 21 is a metal pipe, and the vertical movement caused by the linear expansion of metal due to air temperature fluctuations and ground temperature fluctuations is not taken into consideration. Second, since the middle pipe 22 sinks in conjunction with the soft ground, it is necessary to temporarily raise the bottom surface from the supporting layer by a height h equivalent to the amount of subsidence, and the inner pipe 21 is exposed to compression and swelling of the soft ground. Both the first and second problems cause the inner pipe 21, which is a stationary shaft, to move up and down, which may result in failure to obtain a measurement of the amount of ground surface subsidence with the required accuracy.

[0005] The object of the present invention is to provide an buried support pillar having a carbon pipe that suppresses up and down movement caused by the linear expansion of the material accompanying the range of soil temperature and air temperature fluctuations to a required value when measuring the amount of land surface subsidence, groundwater level, etc., and a metal pipe that supports the entire support pillar, which is completely insulated and protected by a resin pipe from earth pressure caused by the compression and swelling of soft ground. [Means for solving the problem]

[0006] In the buried support for suppressing vertical movement of the present invention, a carbon pipe having a linear expansion coefficient extremely smaller than that of a metal pipe having vertical strength and rigidity is covered and passed through the inside of the metal pipe, and at a depth underground where the ground temperature fluctuation range is reduced to a required value, the bottom of the carbon pipe is attached to the metal pipe by a support pipe, and the carbon pipe does not come into contact with the metal pipe except through the support pipe. Also, when the metal pipe supporting the carbon pipe is passed through a durable resin pipe buried in a cavity formed in a layer of soft ground by excavation in advance, and the tip of the metal pipe penetrates and is buried in the hard ground, the bottom of the resin pipe is pressed against the hard ground without floating above the hard ground and without any gaps. Effect of the Invention

[0007] As is well known, the amount of linear expansion is calculated by multiplying the temperature fluctuation range by the linear expansion coefficient of the material and the length of the material, and the ground temperature fluctuation range decreases the deeper underground. In the buried support for suppressing vertical movement of the present invention, the linear expansion of the metal pipe that moves the carbon pipe up and down is limited to that associated with the ground temperature fluctuation range between the support pipe and the hard ground. Therefore, by setting the buried depth of the support pipe to a depth underground that reduces the ground temperature fluctuation range to the required value, the vertical movement of the carbon pipe caused by the linear expansion of the metal pipe can be suppressed to the required value. In addition, the characteristic of carbon material is that its linear expansion coefficient is extremely small compared to metal materials, and the vertical movement of the carbon pipe itself due to its linear expansion is also suppressed.

[0009] The resin pipe buried by the method according to the present invention is durable against external physical and chemical influences, and isolates the metal pipe from the soft ground without any gaps, suppressing the up and down movement of the metal pipe caused by compression and swelling of the soft ground.

[0010] By using the buried support pillar for suppressing vertical movement of the present invention, it is possible to measure not only the amount of ground subsidence but also groundwater levels and other measurement data for the environment, construction, civil engineering, etc. with greater accuracy than conventional technology. [Brief description of the drawings]

[0011] [Figure 1] FIG. 2 is a side view of the body of the buried support for suppressing vertical movement of the present invention and the stratum. [Diagram 2] This is soil temperature data for Tokyo at a depth of -1m taken from the "Japanese Soil Temperature Data" homepage of the Mizoguchi Laboratory, Graduate School of Agricultural and Life Sciences, University of Tokyo, and the xls. (1.7M) file published there. This file is said to be a digitalized version of the numerical data published in "Materials on Soil Temperature, etc." (Meteorological Information No. 3, 1982). URL: http: / / www.iai.ga.a.utokyo.ac.jp / mizo / research / soildb / ground_T_db.html [Diagram 3]This is a table and approximate curve of the range of soil temperature fluctuation by depth in Tokyo. Based on the numerical data in Figure 2, the difference between the maximum and minimum soil temperatures by depth was calculated to obtain the range of soil temperature fluctuation by depth. [Figure 4] These are the monthly average daily maximum temperatures and monthly average daily minimum temperatures in Tokyo from 2013 to 2022, as published in the Japan Meteorological Agency data. The URLs are https: / / www.data.jma.go.jp / obd / stats / etrn / view / monthly_s3.php?prec_no=44&block_no=47662&year=&month=&day=&view=a2 and https: / / www.data.jma.go.jp / obd / stats / etrn / view / monthly_s3.php?prec_no=44&block_no=47662&year=&month=&day=&view=a3, respectively. [Diagram 5] This is a list (excerpt) of linear expansion coefficients by material. MISUMI Group Headquarters' MISUMI-VONA technical information "Linear expansion coefficient of materials" URL: https: / / jp.misumi-ec.com / tech-info / categories / plastic_mold_design / pl06 / c0798.html [Figure 6] This is a general property table of fiber reinforced plastics (FRP). Hopec Corporation Technical Information URL: https: / / www.hopec.jp / technology / DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] In an embodiment of the present invention, as shown in FIG. 1, a metal pipe 2 is passed through a buried protective pipe 3, and when the tip of the metal pipe 2 is penetrated into hard ground 10 by an excavation device 5, a vertical motion suppression pipe 1 is placed over the metal pipe 2 and passed through the metal pipe 2, and the bottom of the vertical motion suppression pipe 1 is attached to the metal pipe 2 by a support pipe 4 at a burial depth 11.

[0013] Fig. 1A is a cross-sectional view of a buried vertical motion suppression pillar in an embodiment of the present invention, in which the metal pipe 2 is an iron pipe made of iron material, the vertical motion suppression pipe 1 is a carbon pipe made of CF prepreg material, and the protective pipe 3 is a PVC resin pipe (vinyl chloride pipe). The linear expansion coefficient of the iron pipe is 11.8 as shown in Fig. 5, and that of the carbon pipe is 0.9 to 1.0 as shown in Fig. 6, which is extremely small, less than one tenth of that of the iron pipe. In addition, as shown in Fig. 1B, the PVC pipe and the carbon pipe have caps on the top to prevent the intrusion of rainwater and earth and sand, and the carbon pipe penetrates a hole opened in the protective pipe cap 6, and the iron pipe penetrates a hole opened in the vertical motion suppression pipe cap 7, respectively, and protrudes above ground.

[0014] 1C shows the dimensions of the buried support for suppressing vertical movement and the depth of the stratum at the installation site in this embodiment, where the installation site is in Tokyo, where both the ground surface 8 and the hard ground 10 are horizontal. The measurement sensor is attached to a carbon pipe at a height of 1.5 m above ground.

[0015] When the amount of ground surface subsidence is measured using a buried support for suppressing vertical movement according to this embodiment, the extent to which the vertical movement of the sensor is suppressed by the burial depth 11 is calculated based on data on soil temperature and air temperature in Tokyo, and the effectiveness of the present invention will be verified below.

[0016] The "Ground Temperature Data for Japan" xls file in Figure 2 lists the ground temperatures in Tokyo at depths from 0m to -5m as numerical data by year and month (units: °C x 10). The table in Figure 3 shows the relationship between ground depth and ground temperature fluctuation range in Tokyo, calculated from this numerical data as the difference between the highest and lowest ground temperatures at each depth over the past 10 years. The graph in Figure 3 shows the values ​​in this table plotted as an exponential approximation curve in Excel, and the ground temperature fluctuation range y (°C) in Tokyo can be calculated using the approximation formula in Equation 1, where x (m) is the ground depth.

[0017]

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[0018] Figure 4 shows the monthly average daily maximum and minimum temperatures in Tokyo. The range of temperature fluctuations over the 10 years from 2013 to 2022 is calculated to be 33.5°C, calculated by subtracting the maximum value of 34.1°C in August 2020 from the minimum value of 06°C in January 2018.

[0019] Based on the approximate formula for the range of ground temperature fluctuations in Tokyo in Formula 1 and the range of air temperature fluctuations in Tokyo (33.5°C), when the burial depth 11 is d (m) and the depth underground is x (m), the predicted vertical movement of the sensor L (mm) can be calculated using Formula 2. Note that the iron pipe is completely isolated by a PVC pipe, and the vertical movement of the sensor due to compression and swelling of the soft ground 9 is assumed to be 0.

[0020]

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[0021] In formula 2, the first term is the linear expansion of the iron pipe in the depth section [-5m to dm], the second term is the linear expansion of the carbon pipe in the depth section [dm to 0m], and the third term is the linear expansion of the carbon pipe in the section from the ground surface 8 to 1.5m above ground level. Note that the carbon pipe needs to be longer by the amount that the burial depth 11 is lowered.

[0022] Formula 3 is a formula for calculating the vertical movement L (mm) of the sensor when a carbon pipe is not used, as in the prior art, and the sensor is attached to an iron pipe 1.5 m above ground.

[0023]

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[0024] Table 1 shows the results of calculating the vertical movement L (mm) of the sensor using formula 2 and formula 3. The calculation using formula 2 was limited to obtaining the vertical movement of the sensor for each 50 cm decrease in the burial depth 11 in the range from 0 m to -3.0 m.

[0025] [Table 1]

[0026] From Table 1, it can be seen that as the depth of the burial depth 11 decreases, the integrated value of the ground temperature fluctuation range in the section [-5m to dm] between the burial depth 11 and the hard ground 10 decreases, the linear expansion of the iron pipe in that section is suppressed, and the vertical movement of the sensor attached to the carbon pipe is suppressed accordingly. At this time, the linear expansion of the carbon pipe itself increases slightly, but it is one order of magnitude less than that of the iron pipe, and even if this is taken into account, the tendency does not change. In this embodiment, if it is required to make the vertical movement of the sensor less than 0.65 mm, it is sufficient to make the burial depth 11 deeper than -1 m from Table 1, and this depth -1 m is the "underground depth at which the ground temperature fluctuation range is reduced to the required value". From the above, it has been shown that the vertical movement suppression buried support of the present invention can suppress the vertical movement of the sensor attached to the carbon pipe to the required value. [Explanation of symbols]

[0027] FIG. 1 is a side view of a buried support pillar for suppressing vertical movement. 1 Vertical movement suppression pipe 2 metal tube 3 Protection tube 4 Support tube 5. Drilling Rig 6 Protective tube cap 7 Cap for vertical motion suppression pipe 8 Ground surface 9 Soft ground 10 Hard ground 11 Burial depth 12 Protection tube height above ground

Claims

1. A buried support for suppressing vertical movement is characterized in that a metal pipe having vertical strength and rigidity is covered with a carbon pipe having an extremely small linear expansion coefficient compared to the metal pipe, which is passed through the inside of the metal pipe, and the bottom of the carbon pipe is attached to and supported by a support pipe at a depth underground where the range of ground temperature fluctuation is reduced to the required value.

2. The metal pipe supporting the buried support pillar for suppressing vertical movement according to claim 1 is buried by penetrating its tip into the hard ground through a durable resin pipe buried in a cavity formed in a layer of soft ground by excavation in advance. At that time, the bottom surface of the resin pipe is pressed against the hard ground without floating or leaving any gaps.

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