JPH0552602A - Method for measurement of sink amount of bed by depths - Google Patents

Abstract

PURPOSE:To enable work reduction at measurement points by burying a long pipe so that a metal ring by depths is made in contact with an inner wall of a boring hole and making a measurement of the ring position at an interval by an eddy current sensor inserted into the Pipe. CONSTITUTION:After long pipes of double pipe structure 23 and 25 are inserted into boring holes at measurement points drilled to a specified depth, an outer pipe 25 is extracted and a ring 24 is buried so that the metal ring 24 for each depth and holding soil 27 are made to contact directly with hole inner wall. Next, an eddy current sensor probe 22 at the tip of a cable 8 is inserted into the inner pipe 23 through the ring 24. Using a variation in coil voltage due to eddy current at this time, the position of each ring 24 in depth direction is measured as the initial measurement value. The same measurement is made at an interval, and the measured value is compared with that measured before to measure the amount of sink by depths. Thus work at the measurement points can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of measuring subsidence amount according to depth of a formation.

[0002]

2. Description of the Related Art In recent years, there has been a tendency to use underground, but it is always the fluctuation of the strata that becomes a problem when performing underground construction. Especially in the reclaimed ground and thick embankment layer, subsidence due to consolidation and compression of the formation is unavoidable. This fluctuation phenomenon is measured as the amount of subsidence on the ground surface, but the amount of contraction of each layer that constitutes underground is not uniform due to the soil characteristics and depth of each layer.

Therefore, it is very important to know the amount of fluctuation of subsidence in each underground layer in order to make predictions and countermeasures against ground subsidence. An example of a conventional method for measuring the amount of subsidence according to depth in the stratum will be described with reference to Fig. 6. First, as shown in (a), the boring hole 1 is excavated at the measurement point of the stratum, and the borehole 2 is attached to the boring hole 1. Then, insert the magnet insertion device 3 into the hole holding tube 2 as shown in (b),
A plurality of depth-dependent magnets 4 are sequentially set in the ground around the hole-holding tube 2, and then the magnetic measuring probe 5 is inserted into the hole-holding tube 2 from the measuring instrument 11 on the ground as shown in (c). Then, the magnetic field of each depth-dependent magnet 4 is detected by the same magnetic measurement probe 5, and the result is read by the galvanometer 10 of the measuring instrument 11, and this is used as the initial measurement value.

Then, in the same manner, the magnetic field of each depth-dependent magnet 4 is detected by the magnetic measurement probe 5, and the result is compared with the initial measurement value or the previous measurement value,
As in (d), measure the depth-dependent subsidence of the ground that changes over time. 7 and 8 show measuring means using the above-mentioned magnetic measurement probe. The measuring means is shown in FIG.
As shown in FIG. 2, two bridge type magnetoresistive elements 6a and 6b having opposite polarities are embedded in a synthetic resin columnar body 7, and a magnetic measurement probe 5 and a balance circuit and a magnetic measurement probe 5 are provided. It comprises a measuring device 11 including a galvanometer 10 for detecting the output, and a cable 8 containing a conductor for transmitting the output from the magnetic measurement probe 5 to a balance circuit.

When the magnetic measurement probe 5 is inserted into the hole tube 2 in the boring hole 1 to pass the magnetic field of the depth-dependent magnet 4, two bridge type magnetoresistive elements 6 are inserted.
Since the polarities of a and 6b are opposite to each other, the outputs from these bridge type magnetoresistive elements 6a and 6b are combined to form the locus shown by the solid line in FIG. 8 and when the pointer of the galvanometer 10 shows zero. By reading the scale 9 of the cable 8, the depth direction position of the magnet 4 for each depth can be measured.

[0006]

In the conventional method for measuring the subsidence amount by depth of the formation shown in FIGS. 6, 7 and 8 described above, the magnet insertion device 3 is inserted into the hole holding pipe 2 to provide a plurality of depth-dependent magnets. 4 had to be sequentially set in the ground around the hole-holding tube 2, which required a lot of time to work at the measurement point.

The present invention has been proposed in view of the above problems, and an object thereof is to provide a method for measuring subsidence amount by depth of a formation that can reduce the work at a measurement point.

[0008]

[Means for Solving the Problems] In order to achieve the above object, the method for measuring subsidence amount according to depth of the present invention is to drill a boring hole to a predetermined depth at a measurement point of the formation, and then to form an inner pipe. A long pipe material having a double pipe structure, which is composed of an outer pipe and is pre-filled with a plurality of depth-specific metal rings and holding soil between these inner and outer pipes, is inserted into the boring hole, and then the outer pipe is inserted. The metal ring for each depth and the holding soil are brought into direct contact with the inner wall surface of the boring hole, the metal ring for each depth is buried in the soil, and then the cable is fed out and the eddy current attached to the tip of the cable is removed. The sensor probe is inserted into the inner pipe, and the same eddy current sensor probe is passed through each of the depth-specific metal ring parts. The coil voltage changes due to the eddy current at this time, and the depth direction of the depth-specific metal ring is determined. Measure the position Then, using this as the initial measurement value, the depth direction position of the metal ring for each depth is measured in the same manner thereafter, and the result is compared with the initial measurement value or the previous measurement value to determine the time. It is characterized by measuring the amount of subsidence depending on the depth that changes with time.

[0009]

As described above, the method of measuring subsidence amount according to depth of the present invention comprises first drilling a boring hole to a predetermined depth at the measurement point of the formation, and then forming an inner pipe and an outer pipe between these inner and outer pipes. Insert a long pipe material with a double pipe structure that is pre-filled with a plurality of depth-specific metal rings and holding soil into the boring hole, and then pull out the outer pipe to remove the depth-specific metal rings and the retention The soil is brought into direct contact with the inner wall surface of the boring hole, the metal rings for each depth are buried in the soil, and then the cable is unwound, and the eddy current sensor plug connected to the tip of the cable is inserted into the inner pipe. The same eddy current sensor probe is passed through each of the above-mentioned depth-specific metal rings, and the coil voltage changes due to the eddy current at this time, and the depth direction position of each depth-specific metal ring is measured. And then In the same manner, the depth direction position of each depth-specific metal ring is measured, and the results are compared with the initial measurement value or the previous measurement value, and the subsidence amount of the ground changes with the passage of time. To measure.

[0010]

[Embodiment] Next, a method of measuring subsidence amount according to depth of the present invention will be explained with reference to one embodiment shown in FIGS. 1 to 5. Reference numeral 21 in FIG. 1 is a formation, and reference numeral 21 'is a fixed point. Reference numerals 22 of 1 and 2 are eddy current sensor plugs, 8 is a cable of the eddy current sensor plugs 22, and 32 of FIGS. 2 and 4 are coils of the eddy current sensor plugs.

Reference numeral 31 in FIG. 1 is a controller installed on the ground, 30
The cord reel of the above cable 8 installed on the ground, 33
Is a conductor that connects the coil 32 of the eddy current sensor probe 22 and the controller 31 through the cable 8.
Reference numeral 23 is an inner pipe of a long pipe material having a double pipe structure, and 25 is an outer pipe of a long pipe material having the same double pipe structure. 1, 24 and 24, a plurality of depth-specific metal rings, 26 are flanges formed at the lower end of the inner tube 23, and the flange 26 holds the holding soil 27.

Reference numeral 27 is holding soil, 34 in FIG. 5 is a holding soil input funnel, 35 is a holding soil inputting funnel, and 28 in FIG. 1 is a lid for closing the upper end opening of the inner pipe 23. Two
7 is prevented from entering the inner pipe 23.
Next, the procedure for measuring the amount of subsidence according to depth will be specifically described.
An assembly of the long pipe members 23, 25, each metal ring 24, and the holding soil 27 is created at the factory. That is, as shown in FIG. 5, a holding soil 27 is charged into a holding soil charging shout 35 → a holding soil charging funnel 34 → a long pipe material 23, 25, and then a metal ring 24 for each depth is used. 23, 25, and then the holding soil 27 is put into the holding soil loading shroud 35 → holding soil loading funnel 34 → long pipe material 23, 25. Depth-specific metal rings 24 and holding soil 27 for long pipes 23, 25
By alternately filling between the two, the assembly of the long pipes 23, 25, each metal ring 24, and the holding soil 27 is prepared at the factory, while the boring hole is excavated to a predetermined depth at the measurement point of the formation.

Then, as shown in FIG.
The assembly of 3, 25, each metal ring 24, and holding soil 27 is inserted into the boring hole. Next, as shown in FIG. 1 (B), the outer pipe 25 is pulled out, and the metal rings 24 for each depth and the retaining soil 27 are brought into direct contact with the inner wall surface of the boring hole to bury the metal rings 24 for each depth in the soil. To do. Then, as shown in FIG. 1 (C), the cable 8 is unwound, and the eddy current sensor plug 22 attached to the tip of the cable 8 is attached to the inner pipe 23.
Then, the eddy current sensor probe 22 is passed through the depth-dependent metal rings 24, and the position of the depth-dependent metal rings 24 in the depth direction is measured by the change in the coil voltage due to the eddy current at this time. Then, use this as the initial measurement value.

Thereafter, in the same manner, the depth direction position of each metal ring 24 for each depth is measured, and the result is compared with the initial measurement value or the previous measurement value, and changes with the passage of time. Measure the subsidence amount according to the depth of the ground. FIG. 3 shows an example of the detection voltage of the eddy current sensor probe 22, and the characteristics of (A) and (B) of FIG. 3 can be obtained by winding the coil 33.

FIG. 4 shows an example of a circuit for detecting an eddy current signal by the two coils 32.
a, 32b, a balancer circuit, an oscillator, an AC amplifier and a sync detector.

[0016]

As described above, the method of measuring sedimentation amount according to depth of the present invention comprises drilling a boring hole to a predetermined depth at a measurement point of the formation, and then forming an inner pipe and an outer pipe. Insert a long pipe material of double pipe structure, which is pre-filled with a plurality of depth-specific metal rings and holding soil, into the boring hole, and then pull out the outer pipe. The above-mentioned holding soil is brought into direct contact with the inner wall surface of the boring hole, the metal ring for each depth is buried in the soil, and then the cable is fed out, and the eddy current sensor probe connected to the tip of the cable is inserted into the inner pipe. Then, the same eddy current sensor probe is passed through the above-mentioned depth-specific metal ring parts, and the change in coil voltage due to eddy current at this time causes
The depth direction position of each metal ring according to each depth is measured, and this is used as an initial measurement value. After that, the depth direction position of each metal ring according to each depth is measured in the same manner, and the result and the initial measurement. Since the amount of subsidence depending on the depth of the ground that changes with the passage of time is measured by comparing the measured value or the previous measured value, the magnet insertion device is inserted into the hole-holding pipe as in the conventional method described above, and It is not necessary to sequentially set separate magnets into the ground around the hole-holding tube, which has the effect of reducing the work at the measuring point.

[Brief description of drawings]

FIG. 1 is a work process chart showing an embodiment of a method for measuring the amount of subsidence according to depth of the present invention.

FIG. 2 is a vertical sectional side view showing an eddy current sensor probe.

FIG. 3 is an explanatory diagram showing an example of a detection voltage of an eddy current sensor probe.

FIG. 4 is an explanatory diagram showing an eddy current signal detection circuit.

FIG. 5 is an explanatory diagram showing an example of filling metal pipes and holding soil for each depth between long pipes.

FIG. 6 is a work process diagram showing a conventional method of measuring a subsidence amount according to depth of a stratum.

FIG. 7 is a perspective view showing a measuring means using a magnetic measurement probe.

FIG. 8 is an explanatory diagram of its operation.

[Explanation of symbols] 8 cable 21 stratum 21 'foundation 22 eddy current sensor probe 23, 25 long tubular material of double pipe structure 24 metal ring by depth 27 holding soil

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] October 6, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Full text

[Correction method] Change

[Correction content]

[Document name] Statement

[Title of Invention] Method for measuring subsidence amount by depth of formation

[Claims]

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of measuring subsidence amount according to depth of a formation.

[0002]

2. Description of the Related Art In recent years, there has been a tendency to use underground, but it is always the fluctuation of the strata that becomes a problem when performing underground construction. Especially in the reclaimed ground and thick embankment layer, subsidence due to consolidation and compression of the formation is unavoidable. This fluctuation phenomenon is measured as the amount of subsidence on the ground surface, but the amount of contraction of each layer that constitutes underground is not uniform due to the soil characteristics and depth of each layer.

Therefore, it is very important to know the amount of fluctuation of subsidence in each underground layer in order to make predictions and countermeasures against ground subsidence. An example of a conventional method for measuring the amount of subsidence according to depth in the stratum will be described with reference to Fig. 6. First, as shown in (a), the boring hole 1 is excavated at the measurement point of the stratum, and the borehole 2 is attached to the boring hole 1. Then, insert the magnet insertion device 3 into the hole holding tube 2 as shown in (b),
A plurality of depth-dependent magnets 4 are sequentially set in the ground around the hole-holding tube 2, and then the magnetic measuring probe 5 is inserted into the hole-holding tube 2 from the measuring instrument 11 on the ground as shown in (c). Then, the magnetic field of each depth-dependent magnet 4 is detected by the same magnetic measurement probe 5, and the result is read by the galvanometer 10 of the measuring instrument 11, and this is used as the initial measurement value.

Then, in the same manner, the magnetic field of each depth-dependent magnet 4 is detected by the magnetic measurement probe 5, and the result is compared with the initial measurement value or the previous measurement value,
As in (d), measure the depth-dependent subsidence of the ground that changes over time. 7 and 8 show measuring means using the above-mentioned magnetic measurement probe. The measuring means is shown in FIG.
As shown in FIG. 2, two bridge type magnetoresistive elements 6a and 6b having opposite polarities are embedded in a synthetic resin columnar body 7, and a magnetic measurement probe 5 and a balance circuit and a magnetic measurement probe 5 are provided. It comprises a measuring device 11 including a galvanometer 10 for detecting the output, and a cable 8 containing a conductor for transmitting the output from the magnetic measurement probe 5 to a balance circuit.

When the magnetic measurement probe 5 is inserted into the hole tube 2 in the boring hole 1 to pass the magnetic field of the depth-dependent magnet 4, two bridge type magnetoresistive elements 6 are inserted.
Since the polarities of a and 6b are opposite to each other, the outputs from these bridge type magnetoresistive elements 6a and 6b are combined to form the locus shown by the solid line in FIG. 8 and when the pointer of the galvanometer 10 shows zero. By reading the scale 9 of the cable 8, the depth direction position of the magnet 4 for each depth can be measured.

[0006]

In the conventional method for measuring the subsidence amount by depth of the formation shown in FIGS. 6, 7 and 8 described above, the magnet insertion device 3 is inserted into the hole holding pipe 2 to provide a plurality of depth-dependent magnets. 4 had to be sequentially set in the ground around the hole-holding tube 2, which required a lot of time to work at the measurement point.

The present invention has been proposed in view of the above problems, and an object thereof is to provide a method for measuring subsidence amount by depth of a formation that can reduce the work at a measurement point.

[0008]

[Means for Solving the Problems] In order to achieve the above object, the method for measuring subsidence amount according to depth of the present invention is to drill a boring hole to a predetermined depth at a measurement point of the formation, and then to form an inner pipe. A long pipe material having a double pipe structure, which is composed of an outer pipe and is pre-filled with a plurality of depth-specific metal rings and holding soil between these inner and outer pipes, is inserted into the boring hole, and then the outer pipe is inserted. The metal ring for each depth and the holding soil are brought into direct contact with the inner wall surface of the boring hole, the metal ring for each depth is buried in the soil, and then the cable is fed out and the eddy current attached to the tip of the cable is removed. The sensor probe is inserted into the inner pipe, and the eddy current sensor probe is passed through the metal rings for each depth. The change in coil voltage due to the eddy current at this time causes the depth direction of the metal rings for each depth. Measure the position Then, using this as the initial measurement value, the depth direction position of the metal ring for each depth is measured in the same manner thereafter, and the result is compared with the initial measurement value or the previous measurement value to determine the time. It is characterized by measuring the amount of subsidence depending on the depth that changes with time.

[0009]

As described above, the method of measuring subsidence amount according to depth of the present invention comprises first drilling a boring hole to a predetermined depth at the measurement point of the formation, and then forming an inner pipe and an outer pipe between these inner and outer pipes. Insert a long pipe material with a double pipe structure that is pre-filled with a plurality of depth-specific metal rings and holding soil into the boring hole, and then pull out the outer pipe to remove the depth-specific metal rings and the retention The soil is brought into direct contact with the inner wall surface of the boring hole, the metal rings for each depth are buried in the soil, and then the cable is unwound, and the eddy current sensor probe attached to the tip is inserted into the inner pipe, The same eddy current sensor probe is passed through the metal rings for each depth, and the position of the metal ring for each depth in the depth direction is measured by the change in the coil voltage due to the eddy current at this time. And then In the same manner, the depth direction position of each depth-specific metal ring is measured, and the results are compared with the initial measurement value or the previous measurement value, and the subsidence amount of the ground changes with the passage of time. To measure.

[0010]

[Embodiment] Next, a method of measuring subsidence amount according to depth of the present invention will be explained with reference to one embodiment shown in FIGS. 1 to 5. Reference numeral 21 in FIG. 1 is a formation, and reference numeral 21 'is a fixed point. Reference numerals 22 of 1 and 2 are eddy current sensor probes, 8 is a cable of the eddy current sensor probe 22, and 32 of FIGS. 2 and 4 are coils of the eddy current sensor probe 22.

Reference numeral 31 in FIG. 1 is a controller installed on the ground, 30
The cord reel of the above cable 8 installed on the ground, 33
Is a conductor that connects the coil 32 of the eddy current sensor probe 22 and the controller 31 through the cable 8.
Reference numeral 23 is an inner pipe of a long pipe material having a double pipe structure, and 25 is an outer pipe of a long pipe material having the same double pipe structure. 1, 24 and 24, a plurality of depth-specific metal rings, 26 are flanges formed at the lower end of the inner tube 23, and the flange 26 holds the holding soil 27.

Reference numeral 27 is a holding soil, 34 is a holding soil input funnel, 35 is a holding soil input funnel, and 35 in FIG. 1 is a lid for closing the upper end opening of the inner pipe 23. Two
7 is prevented from entering the inner pipe 23.
Next, the procedure for measuring the amount of subsidence according to depth will be specifically described.
An assembly of the long pipe members 23, 25, each metal ring 24, and the holding soil 27 is created at the factory. That is, as shown in FIG. 5, a holding soil 27 is charged into the holding soil loading shroud 35, the holding soil loading funnel 34, and the long pipes 23 and 25 at a fixed amount, and then the metal ring 24 for each depth is used. 23, 25, and then the holding soil 27 is put into the holding soil inputting machine 35 → the holding soil inputting funnel 34 → the long pipe material 23, 25, and then this operation is repeated. Depth-specific metal rings 24 and holding soil 27 for long pipes 23, 25
By alternately filling between the two, the assembly of the long pipes 23, 25, each metal ring 24, and the holding soil 27 is prepared at the factory, while the boring hole is excavated to a predetermined depth at the measurement point of the formation.

Then, as shown in FIG.
The assembly of 3, 25, each metal ring 24, and holding soil 27 is inserted into the boring hole. Next, as shown in FIG. 1 (B), the outer pipe 25 is pulled out, and the metal rings 24 for each depth and the retaining soil 27 are brought into direct contact with the inner wall surface of the boring hole to bury the metal rings 24 for each depth in the soil. To do. Next, as shown in FIG. 1 (C), the cable 8 is unwound, and the eddy current sensor probe 22 attached to the tip of the cable 8 is attached to the inner tube 23.
Inserted into the inside, the same eddy current sensor probe 22 is passed through each depth-specific metal ring 24 part, and the depth direction position of each depth-specific metal ring 24 is measured by the change of the coil voltage due to the eddy current at this time. Then, use this as the initial measurement value.

Thereafter, in the same manner, the depth direction position of each metal ring 24 for each depth is measured, and the result is compared with the initial measurement value or the previous measurement value, and changes with the passage of time. Measure the subsidence amount according to the depth of the ground. FIG. 3 shows an example of the detected voltage of the eddy current sensor probe 22, and the characteristics of (A) and (B) of FIG. 3 can be obtained depending on the winding method of the coil 33.

FIG. 4 shows an example of a circuit for detecting an eddy current signal by the two coils 32.
a, 32b, a balancer circuit, an oscillator, an AC amplifier and a sync detector.

[0016]

As described above, the method of measuring sedimentation amount according to depth of the present invention comprises drilling a boring hole to a predetermined depth at a measurement point of the formation, and then forming an inner pipe and an outer pipe. Insert a long pipe material with a double pipe structure pre-filled with a plurality of depth-specific metal rings and holding soil into the boring hole, then remove the outer pipe, and remove the depth-specific metal rings and The holding soil is brought into direct contact with the inner wall surface of the boring hole, the metal ring for each depth is buried in the soil, and then the cable is fed out, and the eddy current sensor probe attached to the tip is inserted into the inner pipe. Then, the same eddy current sensor probe is passed through the metal rings for each depth, and the change in coil voltage due to eddy current at this time causes
The depth direction position of each metal ring according to each depth is measured, and this is used as an initial measurement value. After that, the depth direction position of each metal ring according to each depth is measured in the same manner, and the result and the above initial measurement. Since the amount of subsidence depending on the depth of the ground that changes over time is measured by comparing the measured value or the previous measurement value, the magnet insertion device is inserted into the borehole as in the conventional method described above, and It is not necessary to sequentially set separate magnets into the ground around the hole-holding tube, which has the effect of reducing the work at the measurement point.

[Brief description of drawings]

FIG. 1 is a work process chart showing an embodiment of a method for measuring the amount of subsidence according to depth of the present invention.

FIG. 2 is a vertical side view showing an eddy current sensor probe.

FIG. 3 is an explanatory diagram showing an example of a detection voltage of an eddy current sensor probe.

FIG. 4 is an explanatory diagram showing an eddy current signal detection circuit.

FIG. 5 is an explanatory diagram showing an example of filling metal pipes and holding soil for each depth between long pipes.

FIG. 6 is a work process diagram showing a conventional method of measuring a subsidence amount according to depth of a stratum.

FIG. 7 is a perspective view showing a measuring means using a magnetic measurement probe.

FIG. 8 is an explanatory diagram of its operation.

[Explanation of symbols] 8 cable 21 stratum 21 'foundation 22 eddy current sensor probe 23 inner pipe of long pipe material with double pipe structure 24 metal ring according to depth 25 outer pipe of long pipe material with double pipe structure 27 holding soil ─ ─────────────────────────────────────────────────── ──

[Procedure amendment]

[Submission date] October 6, 1992

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 1

[Correction method] Change

[Correction content]

[Figure 1]

Claims (1)

[Claims] 1. A boring hole is drilled up to a predetermined depth at a measurement point in a formation, and is then prefilled with an inner pipe and an outer pipe, and a plurality of depth-dependent metal rings and holding soil are provided between these inner and outer pipes. Inserting the long pipe material of the double pipe structure into the boring hole, removing the outer pipe, and directly contacting the metal ring for each depth and the retaining soil with the inner wall surface of the boring hole. The metal ring for each depth is buried in the soil, then the cable is extended, the eddy current sensor probe attached to the tip of the cable is inserted into the inner pipe, and the eddy current sensor probe is passed through each metal ring for each depth. Then, due to the change in coil voltage due to the eddy current at this time,
The depth direction position of each metal ring according to each depth is measured, and this is used as an initial measurement value. After that, the depth direction position of each metal ring according to each depth is measured in the same manner, and the result and the above initial measurement. A method for measuring the amount of subsidence by depth in a stratum, which is characterized by measuring the amount of subsidence by depth that changes with the passage of time by comparing the measured value or the previous measurement value.