JP7246883B2 - Underground Displacement Meter and Underground Displacement Calculation Method - Google Patents

Description

The present invention relates to an underground displacement gauge for measuring rock displacement in front of a face around a planned tunnel construction area, and an underground displacement calculation method using the underground displacement gauge.

Conventionally, when excavation work is carried out to construct a tunnel structure in the ground, loosening of the ground surrounding the planned tunnel construction area causes not only displacement in the vertical direction, but also in the tunnel axis direction, tunnel transverse direction, etc. It is known to have a three-dimensional effect on the surrounding ground, such as horizontal displacement to the ground. In particular, it is important to measure the preceding displacement in front of the face in advance, because there is a possibility that the face will collapse even during excavation in tunnel construction on soft ground.

Under such circumstances, an inclinometer using a gravitational acceleration sensor or the like is widely known as a measuring instrument capable of monitoring the displacement of the surrounding ground during tunnel excavation. This inclinometer is installed in a borehole extending in the axial direction of the tunnel at the top of the face in front of the tunnel face, and is installed in the borehole to measure settlement of the top of the tunnel during excavation. Although it is possible to measure the displacement in the vertical direction, it is not possible to measure the displacement in the horizontal direction.

On the other hand, a link-type displacement gauge is known as a displacement gauge capable of measuring vertical and horizontal displacements. A link-type displacement gauge, as disclosed in Patent Document 1, for example, consists of alternately connecting cylinders in which sensing means for sensing the displacement of ground and relay rods are connected. Installed on the ground, it continuously calculates the horizontal and vertical displacement of the ground.

JP-A-2000-39316

However, in the link-type displacement meter, the sensing means for measuring horizontal displacement and the sensing means for measuring vertical displacement are installed at different positions in the longitudinal direction of the link-type displacement sensor. The measurement point of vertical displacement is not the same point.

In addition, when a link-type displacement sensor has a large cross-sectional diameter and a wide installation space can be secured, for example, it can be installed on the railroad track laid in an existing tunnel via a support member, making it suitable for excavation work near the existing tunnel. This is suitable for measuring looseness of the ground that accompanies this. However, when measuring the displacement of the ground by inserting and installing it in a borehole provided in the ground, the borehole must have a large standard diameter, which is not suitable.

The present invention has been made in view of such problems, and its main purpose is to measure the horizontal and vertical displacements of the natural ground in front of the face due to tunnel excavation at the same measurement point. An object of the present invention is to provide an underground displacement meter and a ground displacement measuring method that are possible.

In order to achieve this object, an underground displacement gauge of the present invention is an underground displacement gauge that is installed in a hole drilled in the ground to measure the A long member, a plurality of joint members that connect the adjacent long members, and two measuring units that are housed in the joint members and have strain-generating plates on which strain sensors are installed on the plate surface. a pair of joint sleeves arranged in series and connected to ends of the elongate members; and a hollow cylindrical body connected so as to be a pair of joint The pair of joint sleeves is composed of a vertically rotating sleeve and a horizontally rotating sleeve, and one end of the vertically rotating sleeve and one end of the hollow cylindrical body are connected to a horizontal shaft pin. and one end of the horizontal rotation sleeve and the other end of the hollow cylindrical body are connected via a vertical axis pin.

According to the underground displacement meter of the present invention, the two measurement units are arranged in parallel and housed in the joint member with the plate surfaces of the strain plates perpendicular to each other. Therefore, when installing an underground displacement meter in the ground, by arranging the plate surface of the strain plate in the vertical direction and the horizontal direction respectively, the joint member arrangement position is set as the measurement point, and at this measurement point Both vertical and horizontal measurements can be taken. This makes it possible to calculate both the vertical and horizontal underground displacements based on the vertical and horizontal measured values at one measurement point.

In the underground displacement meter of the present invention, the measurement unit includes a fixture for fixing one end of the distorted plate to one of the joint sleeves, and a fixture that fixes the other end to the other joint sleeve so as to be parallel to the plate surface. and a pressing tool that presses slidably in a direction.

According to the underground displacement meter of the present invention, no matter which direction the pair of joint sleeves rotates, the strain plate deforms only in the direction orthogonal to the plate surface on which the strain sensor is installed. It is possible to accurately measure the displacement in the direction desired to be measured by each of the measurement units.

In the underground displacement meter of the present invention, the joint member includes a metal fitting body disposed between the joint sleeve and the elongated member to connect them, and a hole wall of the hole having a tip end on the outer surface of the metal fitting body. A pair of connecting fittings having a plurality of supporting rods installed radially toward the direction of the supporting rods, and at least three or more of the supporting rods including one elastic rod that expands and contracts in the longitudinal direction are installed. Characterized by

According to the underground displacement gauge of the present invention, among the plurality of supporting rods, the elastic rods are arranged vertically upward in a contracted state in the borehole, and the other supporting rods support the underground displacement gauge. When installed in this manner, the elastic rod always presses the vertically upper hole wall, and the other supporting rods also press the hole wall by the reaction force thereof. As a result, even if the surrounding ground is deformed, the underground displacement sensor does not shift in position within the borehole. It becomes possible to change via the joint member.

An underground displacement measuring method according to the present invention is a method of drilling a hole extending in a tunnel excavation direction from the vicinity of the face by placing the underground displacement meter according to any one of claims 1 to 3 in the surrounding ground of a planned tunnel construction area. , and after the strain plates of each of the two measurement units are installed with the plate surfaces facing the vertical direction and the horizontal direction, respectively, the end of the long member located closest to the wellhead side The part is set as a measurement auxiliary point, and the arrangement positions of the plurality of joint members are set as measurement points, and measurement is performed at each of the plurality of measurement points before the start of excavation and every time the face position advances a predetermined distance after the start of excavation, The position coordinates of each of the measurement points at each point in time when the measurements were performed before and after the start of excavation are compared with the position coordinates of the auxiliary measurement points, among the measurement values obtained at the plurality of measurement points. Calculation is performed based on the measured values of the measurement points located on the portal side, and the displacement of the position coordinates before and after excavation at each of the plurality of measurement points is calculated in each of the vertical direction and the horizontal direction.

According to the underground displacement measuring method of the present invention, the underground displacement meter is placed in the hole drilled in the ground, and the plate surfaces of the strain-generating plates provided in the two measurement units are oriented in the vertical direction and the horizontal direction, respectively. To calculate both the horizontal and vertical displacements generated in the ground in front of the face due to excavation of tunnels at each of multiple measurement points with a simple installation method of just installing it on a wall without requiring a lot of time and effort. becomes possible.

Further, an underground displacement measuring method according to the present invention comprises an underground displacement meter according to any one of claims 1 to 3, or a plurality of elongated elongated bodies arranged in series, in the surrounding ground of a planned tunnel construction area. A member, a plurality of joint members that connect the adjacent long members, and two measurement units that are housed in the joint members and include a strain plate having a strain sensor installed on the plate surface, The joint member comprises a pair of joint sleeves arranged in series and connected to ends of the elongate members, and arranged between the pair of joint sleeves so that the joint sleeves are rotatable in directions perpendicular to each other. inside the hollow cylinder, the two measurement units are arranged such that the plate surfaces of the flexural plates are oriented in directions orthogonal to each other, and a pair of the joint sleeves The underground displacement gauge installed in parallel across the face is inserted into the drilled hole extending in the tunnel excavation direction from the vicinity of the face, and the strain-generating plates of each of the two measurement units move the plate surface in the vertical direction. And after installing so as to face in the horizontal direction, set the tunnel entrance side end of the long member located closest to the tunnel entrance as a measurement auxiliary point, set the arrangement positions of the plurality of joint members as measurement points, and before the start of excavation and when excavation is started and the face position advances by a predetermined distance, measurement is performed at each of the plurality of measurement points, and the position coordinates of each of the measurement points before the start of excavation are based on the position coordinates of the measurement auxiliary point, Calculation based on the measurement values of the measurement points located closer to the tunnel entrance than the self among the measurement values obtained at the plurality of measurement points, and the position coordinates of each of the measurement points at each time when the measurement was performed after the start of excavation is based on the position coordinates of the measurement point located on the most tip side of the underground displacement gauge calculated before excavation, and among the measurement values obtained at the plurality of measurement points, the above-mentioned Calculation is performed based on the measured values of the measurement points, and the displacement of the position coordinates before and after excavation at each of the plurality of measurement points is calculated in each of the vertical direction and the horizontal direction.

According to the underground displacement measuring method of the present invention, the ground displacement at each measurement point after the start of excavation is calculated based on the position coordinates of the measurement point that is least affected by the excavation work. It is possible to grasp the behavior of the ground surrounding the tunnel with higher accuracy.

According to the present invention, an underground displacement meter is installed in a hole drilled in the ground so that the plate surfaces of the strain plates provided in each of the two measurement units face the vertical direction and the horizontal direction, respectively. Therefore, it is possible to grasp both the horizontal and vertical displacements of the ground in front of the face due to tunnel excavation at each of a plurality of measurement points.

FIG. 2 is a plan view showing an installation situation of an underground displacement meter in the present embodiment; FIG. 2 is a plan view showing details of an underground displacement meter in the present embodiment; It is a figure which shows the detail of the measurement part of the underground displacement meter in this Embodiment. FIG. 4 is a plan view showing a state in which a horizontal external force acts on the underground displacement meter in the present embodiment; FIG. 4 is a diagram showing coordinate axes when calculating underground displacement in the present embodiment; 4 is a conceptual diagram showing positions of measurement points and angles measured by a measurement unit in the present embodiment. FIG. It is a figure which shows the position coordinate of the measurement point calculated by the 1st calculation method in this Embodiment. FIG. 10 is a diagram showing position coordinates of measurement points calculated by a second calculation method in the present embodiment; It is a figure which shows the example of arrangement|positioning of the measurement part with which the underground displacement meter in this Embodiment is equipped. It is a figure which shows the other example of the measurement part with which the underground displacement meter in this Embodiment is equipped.

TECHNICAL FIELD The present invention relates to an underground displacement gauge for measuring ground displacement in front of a face around a tunnel construction area, which is caused by tunnel excavation work, and an underground displacement measurement method using the underground displacement gauge. be. In this embodiment, a case where an underground displacement meter is installed in the surrounding natural ground located on the side of a planned tunnel construction area is taken as an example, and while explaining the underground displacement measurement method, the details of the underground displacement meter and the A method for calculating ground displacement will be described with reference to FIGS. 1 to 10. FIG.

<<Method for measuring underground displacement: Install an underground displacement meter 10 in the ground>>
At the start of the tunnel excavation work, as shown in the plan view of FIG. 1, the natural ground near the excavation start position is excavated over a wider area than the cross section of the planned tunnel construction area T to construct the widened portion W. After that, a boring hole H is provided in parallel with the tunnel axis C from the widened portion W toward the tunnel excavation direction in front of the face.

In the present embodiment, a boring hole H is constructed in one location of the surrounding natural ground located on the left side of the planned tunnel construction area T when the face is viewed forward, and an underground displacement gauge 10 is installed. However, the underground displacement meter 10 may be provided at any position in the rock surrounding the planned tunnel construction area T, and the number thereof is not limited to one.

Further, in the present embodiment, the underground displacement gauge 10 is installed directly on the hole wall of the borehole H, but a pipe material for protecting the hole wall may be installed inside the borehole H. Alternatively, the underground displacement meter 10 should be installed inside the pipe material. Furthermore, the borehole H does not necessarily have to be parallel to the tunnel axis C, and may be constructed at a predetermined angle with respect to the tunnel axis C.

<Underground Displacement Gauge 10: Long Member 1 and Joint Member 2>
The underground displacement meter 10 inserted and installed in the borehole H includes a plurality of long members 1 arranged in series, a plurality of joint members 2 connecting the adjacent long members 1, and the joint members 2 It is provided with two internal measuring units 3 , and the arrangement positions of the joint members 2 are measurement points P in the underground displacement meter 10 .

As shown in FIGS. 1 and 2, the elongated member 1 is made of, for example, a stainless steel elongated pipe having a square cross section and having high rigidity. set. In the present embodiment, the length of the long member 1 is set to 500 mm in order to set the measurement points P for measuring the underground displacement, for example, every 500 mm. may be

Further, the long member 1 is arranged so that two opposing planes face the vertical direction and the other two planes face the horizontal direction in a cross-sectional view when installed in the boring hole H. A plurality of these long members 1 are arranged in series and connected via joint members 2 .

The joint member 2 includes a hollow cylinder 21 that houses the measuring unit 3, a pair of joint sleeves (a vertical rotation sleeve 22 and a horizontal rotation sleeve 23) connected to both ends of the hollow cylinder 21, and a pair of connecting fittings 27 connected to each of the pair of joint sleeves.

As shown in FIG. 2, the hollow cylinder 21 is made of a highly rigid hollow rectangular cylinder made of stainless steel, for example, having an inner diameter larger than that of the elongated member 1. , but one end of the horizontally rotating sleeve 23 is inserted into the other. Both the vertical rotation sleeve 22 and the horizontal rotation sleeve 23 are configured by a highly rigid prism made of, for example, stainless steel and having the same cross-sectional diameter as the elongated member 1 .

The hollow cylindrical body 21, the vertically rotating sleeve 22, and the horizontally rotating sleeve 23 are installed in the boring hole H in the same manner as the elongated member 1, and when viewed in cross section, the two opposing planes are vertically oriented. , and the other two planes are oriented horizontally.

As shown in FIGS. 2 and 3, one end of the vertical rotation sleeve 22 and one end of the hollow cylindrical body 21 are penetrated by a horizontal shaft pin 25 whose axis extends in the horizontal direction, and a horizontal rotation sleeve 23 is provided. and the other end of the hollow cylindrical body 21 are connected by penetrating a vertical axis pin 26 whose axis extends in the vertical direction. As a result, in the joint member 2, the vertical rotation sleeve 22 swings in the vertical direction about the horizontal shaft pin 25 with respect to the hollow cylindrical body 21, and the horizontal rotation sleeve 23 swings about the vertical shaft pin 26. It functions as a so-called universal joint that swings in the horizontal direction. 3 shows a state in which the hollow cylinder 21 is removed in order to show the inside of the hollow cylinder 21. As shown in FIG.

For this reason, the inner diameter of the hollow cylindrical body 21 is such that not only the vertical rotation sleeve 22 and the horizontal rotation sleeve 23 can be inserted, but also the vertical rotation of the vertical rotation sleeve 22 and the horizontal rotation of the horizontal rotation sleeve 23 can be performed. Admissible size is guaranteed. On the other hand, the outer diameter of the hollow cylindrical body 21 is preferably molded to such an extent that it can be inserted into and installed in a boring hole H having a minimum standard value (generally a diameter of 66 mm).

Further, as shown in FIG. 2, connecting fittings 27 are connected to the other ends of each of the vertically rotating sleeve 22 and the horizontally rotating sleeve 23, one ends of which are connected to the hollow cylindrical body 21, respectively. The elongated member 1 is connected via the fitting 27 .

The connecting fitting 27 has a long metal fitting main body 271 formed by bending a belt-shaped steel plate, and a pair of connection plates 272 are provided at both ends of the metal fitting main body 271 in the longitudinal direction. One connection plate 272 is fastened to the other end of the vertical rotation sleeve 22 or the horizontal rotation sleeve 23 via fasteners 24 such as bolts. It is fastened via the fitting 24 .

In order to allow the connecting fitting 27 to function as a centralizer of the underground displacement meter 10, the metal fitting main body 271 is provided with an elastic member 273a extending and contracting in the longitudinal direction, such as a spring, and a screw or the like. Three support rods 273 are radially provided, each consisting of two length adjustment rods 273b having a length adjustment function. Each of these is installed so as to extend radially from the axis of the metal fitting main body 271, and a ball caster is installed at the tip. The number of length adjusting rods 273b is not limited to two, and three or more may be provided.

The hollow cylindrical body 21, the vertically rotating sleeve 22, the horizontally rotating sleeve 23, and the connecting fitting 27, which constitute the joint member 2, are connected with each other in such a manner that their axes are aligned on the same line. . The long member 1 connected to these joint members 2 is also connected so that its axis is positioned on the same line as the axis of the joint member 2 .

In the underground displacement meter 10 having the above-described configuration, the axis of the underground displacement meter 10 coincides with the axis of the borehole H, and the three support members 273 provided on the connecting fitting 27 abut against the hole wall. After adjusting the lengths of the two length adjusting rods 273b of the support member 273, the ball casters are inserted and installed while being brought into contact with the hole wall. At this time, the elastic rod 273a is arranged vertically upward in a contracted state, and the underground displacement gauge 10 is installed so as to be supported by the two length adjusting rods 273b.

Then, in the borehole H, the elastic rod 273a always presses the hole wall vertically upward, and the two length adjustment rods 273b also press the hole wall by the reaction force, resulting in underground displacement. A total of 10 are fixed against the bore wall. Therefore, even when the surrounding ground is deformed, the underground displacement meter 10 does not cause displacement in the boring hole H, and follows the behavior of the surrounding ground to move the adjacent long members 1. It becomes possible to change the angle through the joint member 2 .

≪Underground Displacement Measurement Method: Measurement of Ground Displacement≫
As described above, after the underground displacement gauge 10 is inserted and installed in the borehole H, measurement is performed before starting excavation of the planned tunnel construction area T and every time the face position advances by a predetermined distance after the start of excavation. Each of the points P is measured by the measuring unit 3 housed in the joint member 2, and the position coordinates of each of the measurement points P and the horizontal and vertical displacements are calculated.

<Underground displacement meter 10: measurement unit 3>
The measurement unit 3 applies an external force to the underground displacement meter 10 due to the deformation of the surrounding ground caused by excavating the planned tunnel construction area T, and the long members 1 connected via the joint member 2 are displaced. The angle (angle in the horizontal direction and angle in the vertical direction) is measured when they are adjacent to each other at an angle. In this embodiment, as shown in FIG. 2, two measurement units 3 are arranged inside a hollow cylinder 21 that constitutes the joint member 2, and the two measurement units 3 are arranged by the hollow cylinder 21. are protecting.

As shown in FIG. 3, each of the two measurement units 3 includes a strain plate 31, a fixture 32, and a presser 33. A strain sensor 34 is installed on each of the front and back sides. These two measurement units 3 are arranged in parallel with the plate surfaces of the flexural plates 31 orthogonal to each other, and straddle the vertical rotation sleeve 22 and the horizontal rotation sleeve 23 inside the hollow cylindrical body 21 . However, depending on the direction in which it is installed, it is treated as a horizontal measurement unit 3a for measuring horizontal angles or as a vertical measurement unit 3b for measuring vertical angles.

In the horizontal measurement unit 3a for measuring the horizontal angle, one end of the strain plate 31 is fixed to one end of the horizontal rotation sleeve 23 by a fixture 32 with the plate surface of the strain plate 31 facing the horizontal direction. The other end of the distorting plate 31 is pressed against one end of the vertically rotating sleeve 22 via a pressing tool 33 so as to be slidable in a direction parallel to the plate surface.

The pressing member 33 may have any structure, but in the present embodiment, it is composed of a pressing plate 331 and a fixing member 332 such as a bolt for fixing the pressing plate 331 to the vertically rotating sleeve 22. The other end of the strain plate 31 is sandwiched between the pressing plate 331 and the surface of the vertically rotating sleeve 22 with a pressing force that allows the sliding.

On the other hand, the vertical measurement unit 3b for measuring the angle in the vertical direction is arranged such that one end of the distorting plate 31 is attached to one end of the vertically rotating sleeve 22 with the plate surface of the distorting plate 31 facing the vertical direction. , and the other end of the distorting plate 31 is pressed against one end of the horizontally rotating sleeve 23 via a pressing tool 33 so as to be slidable in a direction parallel to the plate surface.

Therefore, for example, when a horizontal external force acts on the vicinity of the joint member 2, the horizontally rotating sleeve 23 connected to the elongated member 1 rotates horizontally with respect to the hollow cylinder 21, as shown in FIG. do. As a result, the strain plate 31 of the horizontal measurement unit 3a slides on the vertically rotating sleeve 22, and the plate surface bends to form a convex surface in the horizontal direction. The strain sensor 34 installed on the plate surface detects this and outputs an electric signal, and from this output value, the horizontal angle αh between the adjacent long members 1 via the joint member 2 can be obtained. .

At this time, the strain plate 31 that constitutes the vertical measurement unit 3b slides on the horizontal rotation sleeve 23 in the direction parallel to the plate surface, so that it is not deformed, and the horizontal force caused by the action of the horizontal force does not cause deformation. The swinging motion of the rotating sleeve 23 is not hindered.

Similarly, when an external force acts in the vicinity of the joint member 2 in the vertical direction, the vertical rotation sleeve 22 rotates in the vertical direction with respect to the hollow cylinder 21 . Then, the strain plate 31 constituting the vertical measurement unit 3b slides on the horizontally rotating sleeve 23, and the plate surface bends to form a convex surface in the vertical direction. This is detected by the strain sensor 34 installed on the plate surface, and the vertical angle αv between the adjacent long members 1 can be obtained.

In this way, the strain plate 31 is deformed only in the direction perpendicular to the plate surface on which the strain sensor 34 is installed, regardless of which way the pair of joint sleeves 22 and 23 rotates. It is possible to accurately measure the angle in the direction desired to be measured by each of the portions 3b.

As described above, the underground displacement meter 10 has two measurement units 3, the horizontal measurement unit 3a and the vertical measurement unit 3b, which are arranged in parallel in the joint member 2. At the point P, it is possible to measure both the horizontal angle αh, which is the measurement value of the horizontal measurement unit 3a, and the vertical angle αv, which is the measurement value of the vertical measurement unit 3b.

Since both the horizontal angle αh and the vertical angle αv can be measured at each measurement point P, the horizontal and vertical position coordinates can be calculated. It is possible to calculate both the horizontal displacement uh and the vertical displacement uv of .

<Method for calculating position coordinates of measurement point P and underground displacement uh, uv>
A method of calculating the position coordinates at the measurement point P and the underground displacement will be described below. In the present embodiment, a method of calculating the position coordinates in plan view and the horizontal displacement uh will be described as an example, and two patterns of the calculation method (first calculation method and second calculation method) will be described.

In addition, in calculating the position coordinates in plan view and the horizontal displacement uh at the measurement point P, as shown in FIG. use. The auxiliary measurement point Ps refers to the arrangement position of the portal-side end of the portal-side elongated member 1a positioned closest to the portal of the underground displacement meter 10, and the measured values are shown in FIGS. 6(a) and (b). , the position coordinates (x0, y0) of the wellhead-side end portion of the wellhead-side elongated member 1a in plan view and the horizontal direction of the corner formed by the extending direction of the wellhead-side elongated member 1a and the tunnel axis C The inclination angle is βh0.

Also, as shown in FIG. 5, the X-axis is the direction of the tunnel axis C (the + direction is the excavation direction), and the Y-axis is the direction orthogonal to the tunnel axis C (the - direction is the direction approaching the tunnel axis C). . Note that the vertical direction (the minus direction is vertically downward) is the Z axis.

<First Calculation Method: Method of Calculating in Order from the Entrance Side of the Underground Displacement Meter 10 to the Tip>
In describing the first calculation method, a plurality of measurement points Pi (i = 1 to the number of measurement points) are, as shown in FIG. is a measurement point P1, and are arranged in ascending order toward the tip of the underground displacement meter 10. As shown in FIG. In FIG. 6A, four measurement points Pi (i=1 to 4) are shown as an example, and the distance between the measurement points Pi is L. In FIG.

In the first calculation method, the position coordinates are calculated in order from the reference point P1 located on the portal side toward the tip side, using the measured value of the auxiliary measurement point Ps located in the widened portion W as a reference.

First, after installation of the underground displacement meter 10 and before starting excavation of the planned tunnel construction area T, as shown in FIG. and the horizontal inclination angle βh0 of the face position long member 1a with respect to the tunnel axis C is actually measured. At the same time, the horizontal angle αhi, which is the measurement value of the horizontal measurement unit 3a, is measured for each measurement point Pi.

Next, for each measurement point Pi, the inclination angle βhi in the horizontal direction with respect to the tunnel axis C is calculated using the following equation (1), the actually measured inclination angle βh0, and the measured angle αhi.

The positional coordinates of the planar view at each measurement point Pi are calculated by Equation (2) based on the previously measured positional coordinates (x0, y0) of the auxiliary measurement point Ps and βhi calculated by Equation (1).

Calculations by the above formulas (1) and (2) are repeated in order from the measurement point P1 located on the entrance side of the underground displacement meter 10 toward the tip, and each position coordinate (xi, yi) is calculated.

A procedure similar to the above is repeated every time the face position advances by a predetermined distance after the start of excavation of the planned tunnel construction region T. Since the positional coordinates (x0, y0) of the auxiliary measurement point Ps and the horizontal inclination angle βh0 of the portal-side elongated member 1a with respect to the tunnel axis C change as the excavation work progresses, it is necessary to actually measure them. is also performed each time the face position advances by a predetermined distance in the same manner as before the start of excavation.

FIG. 7(a) shows a graph showing the calculation results of the position coordinates, and FIG. 7(b) shows a list of the measured values αh by the horizontal measurement unit 3a and the inclination angles βh in the horizontal direction with respect to the tunnel axis C. As shown in FIG. Note that the distance L between the measurement points Pi is 1000 mm. In FIG. 7, the above-described first calculation method is performed four times in total, at face position A (before the start of excavation) and at face positions B to D (when position coordinates are calculated). Looking at this, as the excavation work progresses and the face progresses from face position A to face position D, the auxiliary measurement point Ps and the measurement points P1 to P4 gradually move toward the tunnel axis (- direction of the Y axis). You can see what you are doing. In particular, at the face position C and the face position D, the position coordinates of the measurement point P2 have moved more toward the tunnel axis than the other measurement points, including the possibility that the ground near the measurement point P2 is soft. You can also see how it is.

Next, for each of the measurement points Pi (i = 1 to the number of measurement points), the position coordinates (initial coordinates) at the time of the face position A (before the start of excavation) and the time points of the face positions B to D (the excavation is only a predetermined distance) The difference between the position coordinates at each of the time points BD advanced is calculated, and the horizontal displacement uh at each time point of the face positions B to D is calculated. The horizontal displacement uh is a vector (ux, uy) consisting of x-direction displacement ux and y-direction displacement uy in the xy plane as shown in FIG.

In this case, the position coordinates in plan view of each of the measurement points Pi at the face position A (before the start of excavation) calculated in advance are used as initial coordinates and substituted into (xi0, yi0) in the equation (3), and each measurement value A displacement uhi of Pi is calculated.

The displacement uh at the measurement auxiliary point Ps of the widened portion W can also be calculated by the above equation (3) in the same manner as the measurement point Pi. In this case, the position coordinates of the measurement assistance point Ps at the previously measured face position A (before the start of excavation) are used as the initial coordinates and substituted into (xi0, yi0) in the equation (3) to obtain the face positions B to D. The displacement uh is calculated by substituting the position coordinates of the measurement assistance point Ps at each time point into (xi, yi).

Further, when calculating the displacement uv in the vertical direction, instead of the position coordinates (x0, y0) of the measurement assistance point Ps and the horizontal inclination angle βh0 of the face position long member 1a with respect to the tunnel axis C, the measurement assistance The position coordinates (x0, z0) of the point Ps and the vertical inclination angle βv0 of the face position long member 1a with respect to the tunnel axis C are actually measured. At the same time, for each measurement point Pi, the vertical angle αvi is measured using the vertical measurement unit 3b. Using these, the vertical position coordinates and the vertical displacement uv of each measurement point Pi may be calculated according to the above procedure. Note that the vertical displacement uv is a vector (ux, uz) consisting of x-direction displacement ux and z-direction displacement uz in the xz plane as shown in FIG.

According to the underground displacement measuring method described above, the underground displacement gauge 10 is placed in the boring hole H drilled in the ground, and the plate surfaces of the strain-generating plates 31 provided in the two measuring units 3 are vertically and horizontally. It is a simple installation method that only needs to be installed so that it faces the direction, and at each of a plurality of measurement points Pi, horizontal displacement uh and vertical displacement uh that occur in the ground ahead of the face due to tunnel excavation can be measured without a lot of time and effort. It becomes possible to calculate both displacements uv. Values to be actually managed are values ux, uy, and uz obtained by decomposing the calculated horizontal displacement uh and vertical displacement uv into respective direction components.

<Second calculation method: method of calculating from the tip of the underground displacement meter 10 toward the rear end (face side)>
In the first calculation method, each measurement point Pi (i = 1 to the number of measurement points), but in the second calculation method, each measurement point Pi (i = 0 to (quantity of measurement points - 1)) is set. That is, the measurement point located closest to the tunnel entrance of the underground displacement meter 10 is defined as the measurement point P1, and the measurement point P1 is arranged toward the tip of the underground displacement meter 10 in ascending order, and Let P(n-1). A measurement point Pn is positioned at the farthest tip side of the underground displacement meter 10, and a measurement auxiliary point Ps set in the widened portion W is a measurement point P0. Note that FIG. 6B shows four measurement points as an example (i=0 to 3, n=4).

In the second calculation method, unlike the first calculation method, the position coordinates of the measurement point Pn located on the tip side of the underground displacement meter 10 are used as the reference, and the measurement position located closest to the tunnel entrance is measured. Position coordinates are calculated in order up to the point P1 and the measurement auxiliary point Ps.

First, after installation of the underground displacement meter 10 and before starting excavation of the planned tunnel construction area T, the measurement point Pi (i = 0 to (n-1)), For each Pn, horizontal inclination angles βhi and βhn with respect to the tunnel axis C and position coordinates (xi, yi) and (xn, yn) are calculated. For the position coordinates (x0, y0) and the inclination angle βh0 of P0 (measurement auxiliary point Ps), actual measurement values are used as described in the first calculation method.

Then, the position coordinates (xn, yn) of the measurement point Pn located on the extreme tip side of the underground displacement meter 10 and the inclination angle βhn in the horizontal direction with respect to the tunnel axis C among the above calculation results were determined, and the excavation work was started. It is treated as a fixed value that does not change even later, and is used in the following equations (4) and (5).

When the excavation work of the planned tunnel construction area T is started and the face position advances by a predetermined distance, the horizontal angle αhi, which is the measurement value of the horizontal measurement unit 3a, is measured at each of the measurement points P1 to P(n−1). to measure

Next, for each measurement point Pi, the inclination angle βhi with respect to the tunnel axis C is calculated by the equation (4). At this time, both the horizontal angle αhn and the horizontal inclination angle βhn with respect to the tunnel axis C are the measured value and the calculated value at the measurement point Pn calculated by the first calculation method before the start of excavation.

After that, the position coordinates of the measurement point Pi in a plan view are determined by the position coordinates (xn, yn) of the measurement point Pn calculated by the first calculation method before the start of excavation, and βhi calculated by the equation (4). Based on, it is calculated from the formula (5).

Calculations by the above formulas (4) and (5) are performed at the measurement point P (n-1) located on the tip side of the underground displacement meter 10 and the measurement point P1 located closest to the portal and the widened portion w The position coordinates (xi, yi) of each measurement point Pi are calculated by repeating in order toward the measurement point P0 (measurement auxiliary point Ps).

The same operation as described above is repeated each time the face position advances by a predetermined distance. In this way, after the start of excavation, the position coordinates of each measurement point Pi can be calculated only by measuring the horizontal angles αh1 to αh(n−1), which are the measured values of the horizontal measurement unit 3a. Unlike the method, there is no need to repeatedly actually measure the position coordinates (x0, y0) of the measurement assistance point Ps and the horizontal inclination angle βh0 of the face position long member 1a with respect to the tunnel axis C.

FIG. 8(a) shows a graph showing the calculation results of the position coordinates, and FIG. 8(b) shows a list of the measured values αh by the horizontal measurement unit 3a and the inclination angles βh in the horizontal direction with respect to the tunnel axis C. As shown in FIG. Note that the distance L between the measurement points Pi is 1000 mm. In FIG. 8, at the face position A (before the start of excavation), the position coordinates are calculated for each of the measurement points P0 to P4 by the first calculation method, and at each of the face positions B to D, the second calculation method is used. Position coordinates of the measurement points P0 to P3 are calculated. At the face positions B to D, as described above, P4 (measurement point Pn located on the extreme tip side of the underground displacement gauge 10) is a fixed value that does not change even after the excavation work is started. We are dealing.

Looking at FIG. 8, similarly to the first calculation method, as the excavation work progresses and the face advances from face position A to face position D, the auxiliary measurement points P0 to P3 gradually approach the tunnel axis in the direction (Y-axis (- direction)). It can also be seen that the position coordinates of the measurement point P2 at the face position D have moved farther toward the tunnel axis than the other measurement points.

It should be noted that the method of calculating the horizontal displacement uh of each measurement point Pi may use equation (3) in the same manner as the method shown in the first calculation method.

Further, when calculating the vertical displacement uv, the position coordinates (x0, y0) of the measurement point P0 (measurement auxiliary point Ps) before the start of excavation and the horizontal direction of the face position long member 1a with respect to the tunnel axis C Instead of the inclination angle βh0, the position coordinates (x0, z0) of the measurement point P0 (measurement auxiliary point Ps) and the vertical inclination angle βv0 of the face position long member 1a with respect to the tunnel axis C are actually measured. At the same time, the vertical angles αvi and αvn, which are the measured values of the vertical measurement unit 3b, are measured for each of the measurement points Pi and Pn. Using these, the vertical position coordinates and the vertical displacement uv of each of the measurement points Pi and Pn can be calculated in the same procedure as above.

According to the underground displacement measurement method described above, the ground displacement at each measurement point Pi after excavation is calculated based on the position coordinates of the measurement point Pn that is least affected by the excavation work. Therefore, it is possible to grasp the behavior of the ground surrounding the planned tunnel construction area T with higher accuracy.

Further, if the first calculation method and the second calculation method are performed together and the calculation results are compared and verified, the reliability of the horizontal displacement uh and the vertical displacement uv can be further improved.

The underground displacement gauge and the underground displacement measuring method using the underground displacement gauge of the present invention are not limited to the above embodiments, and various modifications are possible without departing from the scope of the present invention.

For example, in the present embodiment, one horizontal measuring unit 3a and one vertical measuring unit 3b are used as the measuring unit 3 in the joint member 2, but the present invention is not necessarily limited to this, and as shown in FIG. Both can be installed in pairs. In this case, the positions of the fixture 32 and the pressing tool 33 should be reversed in each of the horizontal measurement section 3a and the vertical measurement section 3b.

In addition, for example, two horizontal measurement units 3a and one vertical measurement unit 3b may be installed in an irregular number depending on the importance of the direction in which the ground characteristics and displacement are grasped. It is also possible to use both the inner and outer surfaces of the vertically rotating sleeve 22 and the horizontally rotating sleeve 23 to provide a maximum of eight measurement units 3 .

Furthermore, the measurement unit 3 is not necessarily limited to the structure shown in FIG. 3. For example, as shown in FIG. A configuration in which both the plate 31 and the pressing plate 331 installed orthogonally thereto may be integrally provided may be employed. In this way, a fixture 32 for fixing the flexure plate 31 to the vertical rotation sleeve 22 or the horizontal rotation sleeve 23 and a fixture 332 for fixing the pressure plate 331 to the vertical rotation sleeve 22 or the horizontal rotation sleeve 23 are provided. Both of them are not required, and the pressing plate 331 is not required to be manufactured separately, so the number of members can be reduced and the configuration can be made simpler.

Further, the underground displacement meter 10 is preferably wirelessly connected to a terminal device (not shown). The terminal device is a so-called notebook computer or tablet terminal that includes an arithmetic processing unit, an input unit, an output unit, a storage unit, and the like. Then, the electric signal of the measurement unit 3 provided in the underground displacement meter 10 is input to the terminal device from the input unit, and the position coordinates and the horizontal displacement of the measurement point P are calculated by the first calculation means in the arithmetic processing unit. A first calculator is stored which calculates uh and vertical displacement uv.

Similarly, a second calculation unit for calculating the position coordinates of the measurement point P, the horizontal displacement uh and the vertical displacement uv by the second calculating means is stored in the arithmetic processing unit. 7 and 8, the administrator displays the calculation result of the measurement point P as shown in FIGS. It is possible to monitor the deformation behavior of the surrounding ground.

Reference Signs List 1 long member 2 joint member 21 hollow cylindrical body 22 vertical rotation sleeve (a pair of joint sleeves)
23 horizontal rotation sleeve (a pair of joint sleeves)
24 fastener 25 horizontal shaft pin 26 vertical shaft pin 27 connecting fitting 271 fitting body 272 connecting plate 273 supporting rod 273a elastic rod 273b length adjusting rod 3 measuring section 3a horizontal measuring section 3b vertical measuring section 31 strain plate 32 Fixing tool 33 Pressing tool 331 Pressing plate 332 Fixing tool 34 Strain sensor 10 Underground displacement gauge H Boring hole P Measurement point T Tunnel construction planned area W Widening part

Claims (6)

An underground displacement meter that is installed in a hole drilled in the ground and measures underground displacement,
a plurality of elongated members arranged in series;
a plurality of joint members that connect the adjacent elongated members;
and two measurement units that are housed in the joint member and that include a strain plate on which a strain sensor is installed on the plate surface,
The joint member
a pair of coupling sleeves arranged in series and connected to ends of the elongate members;
a hollow cylinder disposed between the pair of joint sleeves and connected so that the joint sleeves are rotatable in directions orthogonal to each other;
The two measurement units are installed in parallel across the pair of joint sleeves inside the hollow cylindrical body with the plate surfaces of the strain-generating plates oriented in directions orthogonal to each other ,
The pair of joint sleeves is composed of a vertical rotation sleeve and a horizontal rotation sleeve,
One end of the vertical rotation sleeve and one end of the hollow cylinder are connected via a horizontal axis pin, and one end of the horizontal rotation sleeve and the other end of the hollow cylinder are connected by the vertical axis pin. An underground displacement gauge, characterized by being connected via . In the underground displacement meter according to claim 1,
The measurement unit includes a fixture for fixing one end of the distorted plate to one of the joint sleeves, and a press for pressing the other end of the strain plate against the other joint sleeve so as to be slidable in a direction parallel to the plate surface. An underground displacement gauge comprising: The underground displacement meter according to claim 1 or 2,
The joint member includes a metal fitting body disposed between the joint sleeve and the elongated member to connect them, and a plurality of metal fitting bodies radially installed on the outer surface of the metal fitting body with their tips directed toward the hole wall of the hole. and a pair of connecting fittings having
An underground displacement meter, wherein at least three or more of the support rod members including one elastic rod member that expands and contracts in the longitudinal direction are installed. The underground displacement meter according to any one of claims 1 to 3 is inserted into the ground surrounding the planned tunnel construction area into a drilled hole extending in the tunnel excavation direction from the vicinity of the face, and the two bodies are measured. After the distorted plate of each part is installed so that the plate surface is oriented in the vertical direction and the horizontal direction,
setting the pit-side end of the long member located closest to the pit-side as a measurement auxiliary point, and setting the arrangement positions of the plurality of joint members in which the two measurement units are accommodated as measurement points,
Measurement is performed at each of the plurality of measurement points before the start of excavation and each time excavation is started and the face position advances by a predetermined distance,
The position coordinates of each of the measurement points at each point in time when the measurements were performed before and after the start of excavation are compared with the position coordinates of the auxiliary measurement points, among the measurement values obtained at the plurality of measurement points. Calculated based on the measured values at the measurement points located on the side of the tunnel,
An underground displacement calculation method, wherein the displacement of position coordinates before and after excavation at each of the plurality of measurement points is calculated in each of the vertical direction and the horizontal direction. The underground displacement meter according to any one of claims 1 to 3 is inserted into the ground surrounding the planned tunnel construction area into a drilled hole extending in the tunnel excavation direction from the vicinity of the face, and the two bodies are measured. After the distorted plate of each part is installed so that the plate surface is oriented in the vertical direction and the horizontal direction,
setting the pit-side end of the long member located closest to the pit-side as a measurement auxiliary point, and setting the arrangement positions of the plurality of joint members in which the two measurement units are accommodated as measurement points,
Measurement is performed at each of the plurality of measurement points before the start of excavation and every time the face position advances by a predetermined distance after the start of excavation,
The position coordinates of each of the measurement points before the start of excavation are based on the position coordinates of the measurement auxiliary point, and among the measurement values obtained at the plurality of measurement points, the measurement of the measurement point located on the portal side of the self. calculated based on the value of
The position coordinates of each of the measurement points at each point of time when the measurement was performed after the start of excavation, with reference to the position coordinates of the measurement point located on the most tip side of the underground displacement gauge calculated before excavation, and the plurality of measurement points. Calculation based on the measurement value of the measurement point located on the tip side of the self among the measurement values obtained in
An underground displacement calculation method, wherein the displacement of position coordinates before and after excavation at each of the plurality of measurement points is calculated in each of the vertical direction and the horizontal direction. In the ground surrounding the planned tunnel construction area,
a plurality of elongated members arranged in series;
a plurality of joint members that connect the adjacent elongated members;
and two measurement units that are housed in the joint member and that include a strain-generating plate on which a strain sensor is installed on the plate surface,
The joint member
a pair of coupling sleeves arranged in series and connected to ends of the elongate members;
a hollow cylinder disposed between the pair of joint sleeves and connected so that the joint sleeves are rotatable in directions orthogonal to each other;
an underground displacement meter in which the two measurement units are installed in parallel across the pair of joint sleeves with the plate surfaces of the distorted plates oriented in mutually orthogonal directions inside the hollow cylinder;
After inserting it into a drilled hole extending in the tunnel excavation direction from the vicinity of the face, and installing the strain plate of each of the two measurement units so that the plate surface faces the vertical direction and the horizontal direction,
setting the pit-side end of the long member located closest to the pit-side as a measurement auxiliary point, and setting the arrangement positions of the plurality of joint members in which the two measurement units are accommodated as measurement points,
Measurement is performed at each of the plurality of measurement points before the start of excavation and every time the face position advances by a predetermined distance after the start of excavation,
The position coordinates of each of the measurement points before the start of excavation are based on the position coordinates of the measurement auxiliary point, and among the measurement values obtained at the plurality of measurement points, the measurement of the measurement point located on the portal side of the self. calculated based on the value of
The position coordinates of each of the measurement points at each point in time when the measurement is performed after the start of excavation are determined based on the position coordinates of the measurement point located on the most tip side of the underground displacement gauge calculated before excavation, and the plurality of measurement points. Calculation based on the measurement value of the measurement point located on the tip side of the self among the measurement values obtained in
An underground displacement calculation method, wherein the displacement of position coordinates before and after excavation at each of the plurality of measurement points is calculated in each of the vertical direction and the horizontal direction.

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