JP2000046510A - Method and system for measuring improved body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a highly reliable data without requiring any test work by determining the resistance per unit length using a current between current electrodes and a voltage between potential electrodes under a state where an electrode fixing body are arranged in an improved body to be measured. SOLUTION: An improving body 11 is built in the ground 21 and inserted with an electrode fixing body 3. A pair of current electrodes 4a, 4b fixed to the electrode fixing body 3 are then conducted and a current I flowing between the current electrodes is measured. On the other hand, potential difference V between potential electrodes 4c, 4d fixed to the electrode fixing body 3 is measured. Subsequently, the resistance R per unit length is determined using the measured current I between the current electrodes and the potential difference V between the potential electrodes. Assuming the distance between potential electrodes 4c, 4d is d, R=V/(I.d) is satisfied. Progress of the improving body 11, e.g. diameter, is calculated with reference to the relation between the resistance per unit length and the progress of the improving body 11 using the resistivity of natural ground as a parameter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system for measuring the volume of an improved body formed in the ground and a measuring method therefor.

[0002]

2. Description of the Related Art In some cases, an improved body is formed in the ground for the purpose of improving the ground or receiving a tunnel. For example, in a ground improvement method for improving soft ground, a hardener is injected into the ground by injecting a predetermined hardening agent into the ground at a high pressure while rotating an injection nozzle. A high-pressure injection stirring method for performing cutting and mixing and stirring with the ground is known. According to such a method, a pile-shaped improved body can be formed in soft ground. Also, in the mountain tunnel construction method, a tunnel front receiving construction method (fore piling construction method) is known in which a ground improvement body is formed in an arch shape on the outer periphery of the tunnel prior to tunnel excavation. Can be reinforced.

[0003] By the way, it is important to confirm after the ground improvement or the like that the height of the formed improved body, that is, whether the size, diameter, cross-sectional area, or the like is as intended. However, as a confirmation method, it is common to adopt a method of performing a test work prior to the main work, and directly measuring the yield of the improved body created in the test work by excavating the surrounding area.

[0004]

The measuring method by such a test construction has an advantage that the measurement data is more reliable than the measuring method using an elastic wave, an ultrasonic wave, or the like. Because we have to do some testing work,
There has been a problem that it is disadvantageous in terms of construction period and cost. In addition, there are also problems such as the fact that the test site cannot be performed due to the small size of the site, and that the geological structure of the place where the test work is performed and the site where the main work is performed do not always match.

The present invention has been made in consideration of the above circumstances, and has as its object to provide an improved measurement system and a measurement method capable of obtaining highly reliable data without performing test work. And

[0006]

In order to achieve the above-mentioned object, an improved body measuring system according to the present invention comprises, as described in claim 1, an electrode mounting body arranged in an improved body to be measured; A pair of current electrodes attached to the electrode attachment body, a power supply electrically connected to the pair of current electrodes, a potential electrode attached to the electrode attachment body, and a voltmeter electrically connected to the potential electrode. Calculating means for obtaining a resistance per unit length using a current between the current electrodes and a potential difference between the potential electrodes measured in a state where the electrode mounting body is arranged in the improved body to be measured. The arithmetic means is provided with a relationship between the resistance per unit length prepared in advance with various ground resistivity values as parameters and the yield of the improved body, and the ground ratio measured near the improved body to be measured. With resistance It is obtained by configured to calculate the volume of the improved body to be measured.

According to a second aspect of the present invention, there is provided a method for measuring an improved body, wherein an electrode mounting body is disposed in the improved body to be measured, and a pair of current electrodes mounted on the electrode mounting body. And a potential difference between the potential electrodes is measured using a potential electrode attached to the electrode mounting body, and a current between the current electrodes and the potential electrode are measured. The resistance per unit length is determined using the potential difference between the two, while the ground resistivity near the improved body to be measured is measured, and thereafter, a unit created in advance using various ground resistivity as a parameter. The volume of the improved body to be measured is calculated from the resistance per unit length using the relationship between the resistance per length and the volume of the improved body.

In the improved body measuring system and the measuring method according to the present invention, first, an electrode mounting body is arranged in the improved body to be measured. How to arrange the electrode mounting body is optional, for example, to insert before the improved body is completely solidified, perforate the insertion hole after the improved body is solidified,
A method such as insertion into the insertion hole is conceivable.

Next, current is applied through a pair of current electrodes attached to the electrode mounting body to measure a current between the current electrodes, and the potential electrode is attached to the electrode mounting body using the potential electrode. Measure the potential difference between them.

Next, the resistance per unit length is determined using the measured current between the current electrodes and the potential difference between the potential electrodes.

On the other hand, apart from the above procedure, the ground resistivity near the improved body to be measured is measured. In the measurement of the ground resistivity, after the improved body is created, a portion near the improved body may be set as the measurement position, or, before the improved body is created, the planned portion may be set as the measurement position.

Next, by referring to the relationship between the resistance per unit length prepared in advance using various ground resistivity as a parameter and the yield of the improved body, measurement is made from the resistance per unit length already calculated. Calculate the volume of the target improved body, that is, the cross-sectional area, size, diameter, and the like.

In preparing the relationship between the resistance per unit length and the yield of the improved body in advance, there are two methods, an experimental method and an analytical method. In the former, improved bodies of various sizes were actually created on the ground with various specific resistances, and the surroundings were dug up to measure the improved bodies, and the resistance per unit length at that time was described above. What is necessary is just to ask for like. In the latter case, for example, an axially symmetric FEM model may be created, and the model may be analyzed using the resistivity of the ground as a parameter.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a measurement system and a measurement method for an improved body according to the present invention will be described with reference to the accompanying drawings. It is to be noted that the same reference numerals are given to components and the like that are substantially the same as those in the conventional technology, and description thereof will be omitted.

FIG. 1 is an overall view of an improved measurement system according to this embodiment. As can be seen from the figure, a measurement system 1 for an improved body according to the present embodiment includes a hollow cylindrical electrode mounting body 3 disposed in an improved body to be measured and a material axis along the material axis of the electrode mounting body. An annular electrode 4 ₁ , 4 ₂ , 4 ₃ ,... 4 _n attached to the outer surface thereof; a DC power supply 6 and a voltmeter 7 electrically connected to the electrode via a switch 5;
An arithmetic control unit 8 as arithmetic means for controlling each of these devices
And

The electrode mounting body 3 is made of, for example, hard vinyl chloride,
FRP, although it is preferable to constitute a non-conductive member such as precast concrete, electrodes _{4 1, 4 2, 4 3} , ···· 4 n
In addition, as long as electrical non-contact with the surrounding formed body is ensured, a conductive steel tube or the like may be used.

The DC power supply 6 is only required to be able to flow a DC current, but can output a rectangular wave (alternating DC) by switching the polarity of the power supply in a cycle long enough to be regarded as DC. May be.

The switching device 5, under control of the arithmetic and control unit 8, the electrode 4 _1, 4 _2, 4 _3, of · · · · 4 _n, the desired 2
One electrode is selected as a pair of current electrodes 4a and 4b, and of the remaining electrodes, a desired electrode, for example, two electrodes arranged between the pair of current electrodes 4a and 4b are set as potential electrodes 4c and 4d. You can choose.

The arithmetic and control unit 8 controls the switch 5 to electrically connect the pair of current electrodes 4a and 4b to the DC power source 6 and electrically connect the pair of potential electrodes 4c and 4d to the voltmeter 7, respectively. Activate the DC power source 6 with the current electrode 4
By applying a voltage between a and 4b, the improved body 11 formed around the electrode mounting body 3 is energized as shown in FIG. 2, and the current between the current electrodes 4a and 4b measured in this state and The resistance per unit length is obtained using the potential difference between the potential electrodes 4c and 4d. The arithmetic control unit 8
For example, it can be constituted by a personal computer. The current between the current electrodes 4a and 4b may be measured by, for example, an ammeter (not shown) built in the DC power supply 6.

Further, the arithmetic and control unit 8 measures the relationship between the resistance per unit length prepared in advance using various ground resistivity values as parameters and the volume of the improved body, and measures the vicinity of the improved body 11 to be measured. The volume of the improved body 11 is calculated using the obtained ground resistivity.

Measurement system 1 for improved body according to this embodiment
In the measurement method, first, as shown in FIG. 3, the improved body 11 is formed on the ground 21, and then the electrode mounting body 3 is inserted into the improved body. The electrode attachment 3 may be inserted before the improved body 11 is completely solidified, for example. As a construction method of the improved body 11, a high-pressure injection method or a stirring method using an earth auger can be considered.
Here, it does not matter which construction method is used.

Next, a current is applied through a pair of current electrodes 4a and 4b attached to the electrode mounting body 3 to measure a current I between the current electrodes, and a potential electrode attached to the electrode mounting body 3 is measured. The potential difference V between the potential electrodes is measured using 4c and 4d.

Next, using the measured current I between the current electrodes and the potential difference V between the potential electrodes, a resistance R per unit length is calculated.
Ask for. That is, the distance between the potential electrodes 4c and 4d is d
Then, the resistance R per unit length is R = V / (I ·
d).

On the other hand, apart from the above procedure, the resistivity of the ground near the improved body 11 to be measured is measured. In measuring the specific resistance of the ground, for example, before constructing the improved body 11, it may be measured by using a so-called Wenner method with a planned construction site as a measurement position.

Next, by referring to the relationship between the resistance per unit length prepared in advance and the volume of the improved body using various ground resistivity values as parameters, the resistance R per unit length already calculated is referred to. Improved body 11 to be measured
, For example, its diameter is calculated.

With respect to the relationship between the resistance per unit length and the height of the improved body, for example, the formed body is made into a cylindrical body, and the formed body and the ground extending around the center are centered on the material axis of the formed body. It is obtained by modeling as an axially symmetric FEM model and performing an analysis on the FEM model using the resistivity of the ground as a parameter. In conducting the analysis, the specific resistance of the formed body is naturally required as input data.However, the specific resistance of the improved body formed depending on whether it is stirring mixing of soft ground and mortar, or filling and filling only mortar Causes a certain difference. Therefore, the analytical specific resistance of the formed body is appropriately determined in consideration of the construction method.

FIG. 4 shows that the ground resistivity is 58 Ω · m, 300
The analysis results obtained by using the above-mentioned axial symmetric FEM model for the relationship between the resistance per unit length (Ω / m) and the diameter of the improved body (cm) for the three cases of Ω · m and infinity are shown. FIG.

In order to calculate the diameter of the improved body 11 with reference to such a graph, for example, the resistivity of the ground measured at the site is 300 Ω · m, and the resistance R per unit length is 24 Ω / m.
Then, the diameter of the improved body 11 can be calculated to be 20 cm.

The analysis results as shown in FIG. 4 are stored in a storage device (not shown) in the form of a look-up table, for example.
When the resistance R per unit length measured in the field does not exist in the analysis result, it is preferable to appropriately interpolate the analysis result.

As described above, according to the improved measuring system and method of the present embodiment, the current electrode 4
While the resistance R per unit length is obtained using the current I between a and 4b and the potential difference V between the potential electrodes 4c and 4d, the ground resistivity near the improved body 11 to be measured is measured. The yield of the improved body 11 is calculated from the above-described resistance R per unit length using the relationship between the resistance per unit length and the yield of the improved body prepared in advance using various ground resistivity values as parameters. As a result, the volume of the improved body can be measured efficiently and accurately with higher accuracy than conventional elastic wave or ultrasonic surveys, and without the need to install an elastic wave or ultrasonic transmitter / receiver. It becomes possible.

In addition, since it is not necessary to carry out a test work separately from the main work as in the prior art, it is possible to greatly reduce the construction period and cost for ground improvement work and the like, and in other words, to test the test specimen. Unlike the test work, which was just a test work, it was clarified that the construction area was smaller than the original target because the volume of the improved body could be measured nondestructively and immediately after injection of the hardener. In such a case, it is also possible to take measures such as re-injecting the curing agent, and it is possible to greatly improve the construction quality of ground improvement work and the like.

According to the improved measuring system of the present embodiment, a large number of electrodes 4 ₁ , 4 ₂ , 4 ₃ ,..., 4 _n are provided on the outer surface of the electrode mounting body 3 along the material axis. The electrodes are arranged and electrically connected to a DC power supply 6 and a voltmeter 7 via a switch 5, and the switches are connected to the electrodes 4 ₁ , 4 ₂ , 4 ₃ ,.
· 4 _n of the desired electrode pair of current electrodes 4a, 4b and potential electrodes 4c, so constituted as can be selected arbitrarily as 4d, current electrode Ya suitable for the properties of the specific resistance and improvements of the natural ground Switching of the potential electrode can be performed instantaneously.

Although not specifically mentioned in the present embodiment, the measurement of the current I and the potential difference V for calculating the resistance per unit length described above is performed irrespective of the progress of the hardening of the improved body 11. It is sufficient that the specific resistance of the improved body 11 measured at the site and the specific resistance of the improved body used in the analysis correspond to each other.

Further, in the present embodiment, an example in which the present invention is applied to a ground improvement method has been described. However, the present invention can be applied to all cases where an improved body is formed in the ground. For example, the present invention can be applied to protection work for underground structures, ground reinforcement, tunnel precedent work, and the like.
As shown in the figure, when the presence of the cavity 32 is confirmed in front of the face 31 in tunnel excavation, grout 33 may be injected into the cavity in advance in order to prevent collapse of earth and sand due to excavation. The present invention can also be applied when measuring the creation range of 33.

That is, as shown in the figure, a grouting machine 36 includes a switch 5, a DC power supply 6,
A control device 37 having a built-in voltmeter 7 and an arithmetic control unit 8 is installed. The DC power supply 6 and the voltmeter 7 are connected to the electrode 4 attached to the electrode mounting body 35 via the switch 5 as in the present embodiment. ₁ , 4 ₂ , 4 ₃ ,..., 4 _n are electrically connected.

In performing the measurement, first, the electrode mounting body 35 is inserted into the grout 33, and thereafter, the resistance R per unit length is calculated by the same procedure as in the present embodiment to measure the volume of the grout 33. do it. In this modification, the electrode mounting body 35 also has a function as a grout injection pipe.

In this embodiment, the switch 5 is provided so that the positions and intervals of the current electrode and the potential electrode can be changed so as to cope with the difference in the specific resistance of the ground and the difference in the construction method. Basically, only one pair of the current electrode and the potential electrode is required, and the switch 5 is unnecessary.

Further, in the present embodiment, the electrode mounting body 3 is formed in a hollow cylindrical shape, and the measurement cable is passed through the hollow space. It goes without saying that the measurement cable may be arranged along the peripheral surface.

[0039]

As described above, according to the improved body measuring system according to the first aspect of the present invention and the improved body measuring method according to the second aspect of the present invention, the conventional elastic wave exploration and ultrasonic exploration can be performed. It is also possible to measure the output of the improved body efficiently and accurately with high accuracy and without having to install a transmitting / receiving device for elastic waves or ultrasonic waves. Also,
Since it is no longer necessary to perform test work separately from the main work as in the prior art, it is possible to greatly reduce the construction period and cost of ground improvement work and the like.

[0040]

[Brief description of the drawings]

FIG. 1 is an overall view of a measurement system for an improved body according to an embodiment.

FIG. 2 is a sectional view showing the operation of the improved measurement system according to the embodiment;

FIG. 3 is a cross-sectional view showing a state where an electrode mounting body is inserted into the formed improved body according to the improved body measuring method according to the embodiment.

FIG. 4 shows the relationship between the resistance per unit length (Ω / m) and the diameter (cm) of the improved body in three cases where the ground resistivity is 58 Ω · m, 300 Ω · m, and infinity. 7 is a graph showing an analysis result obtained by using an axially symmetric FEM model.

FIG. 5 is an overall view showing an example in which the improved measurement system according to the present embodiment is applied to a tunnel grout.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS ₁ Measurement system of improved body 3 Electrode mounting body 4 ₁ , 4 ₂ , 4 ₃ ,... 4 _n electrode 4 a, 4 b Current electrode 4 c, 4 d Potential electrode 5 Switch 6 DC power supply (power supply) 7 Voltmeter 8 Calculation Control unit (computing means) 11 Improved body

 ──────────────────────────────────────────────────続 き Continuing on the front page F term (reference) 2D040 AB01 AB03 BB03 BB09 BD05 CB03 GA02 2F063 AA11 AA50 BB10 CA40 EA20 EB21 FA09 FA10 FA16 LA09 LA23 LA25 2F076 BB07 BD02 BE04 BE05 BE19 2G028 AA01 BC06 CG02 DH03 H01N02N

Claims (2)

[Claims] 1. An electrode mounting body disposed in an improved body to be measured, a pair of current electrodes mounted on the electrode mounting body, a power supply electrically connected to the pair of current electrodes, and the electrode mounting A potential electrode attached to the body, a voltmeter electrically connected to the potential electrode, a current between the current electrodes measured in a state where the electrode attachment body is arranged in the improved body to be measured, and Calculating means for calculating the resistance per unit length using the potential difference between the potential electrodes, the calculating means comprising: a resistance per unit length prepared in advance using various ground resistivity values as parameters; Measurement of the improved body characterized in that it is configured to calculate the volume of the improved body to be measured using the relationship with the volume and the ground resistivity measured near the improved body to be measured. system. 2. An electrode mounting body is arranged in an improved body to be measured, and a current is applied between the current electrodes through a pair of current electrodes mounted on the electrode mounting body to measure a current between the current electrodes. The potential difference between the potential electrodes is measured using a potential electrode attached to the mounting body, and the resistance per unit length is determined using the current between the current electrodes and the potential difference between the potential electrodes, while the measurement target Measure the resistivity of the ground near the improved body, and thereafter, the unit length using the relationship between the resistance per unit length and the volume of the improved body prepared in advance using various ground resistivity as parameters A method of measuring an improved body, comprising calculating a volume of the improved body to be measured from a contact resistance.