JP4408077B2 - Measuring method and measuring device of internal strain in lining concrete by ECL method - Google Patents

Description

  The present invention relates to a measuring method and measuring device for internal strain in lining concrete by ECL (extruded concrete lining) method, and in particular, the strain applied to the inside of lining concrete constructed by ECL method is determined from the hardening process of concrete. The present invention relates to a measuring method and measuring device for internal strain in lining concrete by ECL method capable of continuously measuring.

  As a conventional cast-in-place lining shield method, for example, the following is known. This prior art digs a tunnel with a shield machine and installs a formwork along the inner peripheral surface of the tunnel behind the shield machine, In a cast-in-place lining shield construction method in which concrete is placed in a concrete placement space formed between, a plurality of vibration members are arranged along the circumferential direction at the rear edge of the skin plate of the shield machine. By vibrating this vibration member, the concrete in the vicinity of the skin plate is compacted, and the filling property of the concrete in the vicinity of the skin plate, which tends to decrease the filling property, is improved (for example, see Patent Document 1). .

Like the above prior art, the shield construction method in which concrete is placed directly in the concrete placement space formed between the ground and the formwork is less expensive than the shield construction method that uses segments for the lining. It is said that there is. In such a shield construction method in which concrete is directly placed, in order to more appropriately construct the thickness of the lining concrete, external force such as earth pressure and water pressure is applied to the lining concrete as a design document. It is very important to know how it works, i.e. the strain applied to the lining concrete, in particular the internal strain.
JP-A-8-28190 (second page, FIG. 1).

  As in the prior art described in Patent Document 1, lining concrete constructed by placing concrete directly in the concrete placement space formed between the ground and the formwork is strained in the concrete. It is difficult to measure internal strain by embedding a gauge. On the other hand, conventionally, concrete has been subjected to scratches that can embed a strain gauge to temporarily release the pressure of the concrete, and the internal strain is measured by embedding the strain gauge in the concrete. However, in this method, since the concrete pressure is temporarily released, there has been a problem that loosening of the natural ground and filling of the concrete may be insufficient.

  Further, as another conventional method, there is a method in which after the concrete is hardened, the concrete is scratched and the generated compressive strain is released and measured. However, this method has a problem in that it cannot measure strain and internal strain in the hardening process of concrete.

  Therefore, there arises a technical problem to be solved in order to reliably and continuously measure the strain applied to the inside of the lining concrete constructed by the ECL method from the hardening process of the concrete, and the present invention solves this problem. The purpose is to do.

  The present invention has been proposed in order to achieve the above object, and the invention according to claim 1 is characterized in that the inner mold is formed in an annular shape inside the tail portion of the shield excavator while excavating the tunnel with the shield excavator. Of internal strain in lining concrete by ECL construction method in which concrete is directly placed in the concrete placement space formed between the inner formwork and the excavated natural ground In the method, when the inner mold frame is assembled in an annular shape inside the tail portion, the inner mold frame can be extruded into the concrete placement space side through a slit opened in the inner mold frame. A strain gauge is incorporated into the concrete, and a method for measuring internal strain in lining concrete by an ECL method in which the strain gauge is pushed into the placed concrete is provided.

  According to this configuration, when the inner mold is assembled in an annular shape inside the tail portion, the strain gauge is assembled in the frame of the inner mold that is reserved from the concrete placing space side, so that the concrete is cast. Even if the inner periphery seal of the wife mold frame passes over the frame plate on the concrete placement space side in the inner mold before installation, the strain gauge is not damaged. Then, a strain gauge is embedded in the concrete cast in the concrete placement space from the inner mold side through a slit, and the internal strain is measured.

  According to a second aspect of the present invention, when the inner mold frame is assembled in an annular shape inside the tail portion, the inner mold frame is inserted into the frame of the inner mold frame via one side portion of the slit opened in the inner mold frame. The first strain gauge is incorporated into the concrete placement space side so as to be pushed out, and the second strain gauge is incorporated into the concrete placement space side through the other side of the slit so as to be pushed out. Provided is a method for measuring an internal strain in lining concrete by an ECL method in which the first strain gauge and the second strain gauge are pushed into the interior with different depths.

  According to this configuration, the first strain gauge and the second strain gauge are embedded in the placed concrete so that they are relatively close to each other in the circumferential direction and have different indentation depths. Strain is measured.

  According to a third aspect of the present invention, a plurality of strain gauges are incorporated in the inner mold frame assembled in an annular shape at appropriate intervals in the circumferential direction, and the plurality of strain gauges are installed A method for measuring internal strain in lining concrete by the ECL method according to claim 1 or 2, wherein the concrete is pushed into the concrete.

  According to this configuration, a plurality of strain gauges are embedded at appropriate intervals over the entire circumference including the upper and lower sides of the placed concrete, and internal strain is measured at each location by each strain gauge. Is called.

  According to a fourth aspect of the present invention, while excavating a tunnel with a shield excavator, an inner mold is assembled in an annular shape inside the tail portion of the shield excavator, and the inner mold and the excavated ground are between An apparatus for measuring internal strain in lining concrete by an ECL method, in which concrete is directly placed in the formed concrete placement space to construct lining concrete, and is provided on the concrete placement space side of the inner mold. The strain gauge attached to the tip of the push rod, the ball screw shaft, and the ball screw shaft in a state where the rotation of the ball screw shaft is restricted to the portion in the frame of the inner mold frame facing the slit opened in the frame plate A ball screw unit having a drive element screwed to be movable in the axial direction of the ball screw shaft and having a rear end portion of the push rod screwed thereto, and detachably attached to the inner mold side Equipped, on the punching settings were the concrete, to provide an internal strain of the measuring device in lining concrete by ECL method of the strain gauge was pushed into through the slit by driving the ball screw shaft.

  According to this configuration, the strain gauge attached to the tip of the push rod is embedded at a required push depth position in the placed concrete by driving the ball screw shaft. After the strain gauge is embedded, the screwing between the rear end portion of the push rod and the driver is removed and the entire ball screw unit is removed from the inner mold frame side. Thereafter, the internal strain of the concrete is measured by the strain gauge embedded as described above.

  According to the fifth aspect of the present invention, the first push rod is attached to a portion of the inner mold frame facing one side of the slit opened in the frame plate on the concrete placement space side of the inner mold frame. The first strain gauge attached to the tip, the first ball screw shaft, and the first ball screw shaft can move in the axial direction of the first ball screw shaft in a state in which the rotation is restricted. A first ball screw unit screwed and provided with a first driver element screwed at a rear end of the first push rod, and detachably attached to the inner mold side; A second strain gauge attached to the tip of the second push rod that is shorter than the first push rod is provided in a portion of the inner mold frame facing the other side of the slit. , A second ball screw shaft shorter than the first ball screw shaft, and the second A second driver element screwed into the second ball screw shaft so as to be movable in the axial direction in a state where the rotation of the ball screw shaft is restricted, and a rear end portion of the second push rod being screwed. And a second ball screw unit that is detachably attached to the inner formwork side, and the first ball screw shaft is driven into the placed concrete to drive the first ball screw shaft. By pushing a strain gauge through one side part of the slit and driving the second ball screw shaft, the second strain gauge is pushed through the other side part of the slit. Provided is an internal strain measuring device in lining concrete by an ECL method that is pushed into a shallower pushing depth position.

  According to this configuration, the first strain gauge is driven into the required indentation depth position via one side portion of the slit by driving the first ball screw shaft in the placed concrete. Embedded. Further, the second strain gauge is embedded in a required indentation depth position shallower than the first strain gauge through the other side portion of the slit by driving the second ball screw shaft. As a result, the first strain gauge and the second strain gauge are embedded in the required indentation depth positions that are relatively close to each other in the circumferential direction and have different depths. After embedding the first and second strain gauges, the entire first and second ball screw units are removed from the inner mold side. Thereafter, the internal strain of the concrete is measured by the first and second strain gauges embedded as described above.

  According to a sixth aspect of the present invention, a sensor case is detachably attached to a portion in the frame of the inner mold facing the slit opened in the frame plate on the concrete placement space side in the inner mold, and the push rod Is slidably inserted into the bottom plate of the sensor case, and the strain gauge provides an internal strain measuring device in lining concrete by ECL method attached to the tip of the push rod in the sensor case.

  According to this configuration, the strain gauge is incorporated in the sensor case in the inner mold frame that is refrained from the concrete placement space side, and before the concrete is placed, the frame on the concrete placement space side in the inner mold frame. Even if the inner frame seal on the plate passes over the plate, the strain gauge is not damaged. After the strain gauge is embedded in the placed concrete, the sensor case is removed from the inner mold frame after the ball screw unit is removed from the inner mold frame side.

  According to the first aspect of the present invention, when the inner mold frame is assembled in an annular shape inside the tail portion, the inner mold frame can be pushed out into the concrete casting space side through a slit opened in the inner mold frame. Since the strain gauge was inserted into the cast concrete, the strain gauge could be securely embedded in the cast concrete, and the inside of the lining concrete constructed by the ECL method There is an advantage that the strain applied to the can be continuously and reliably measured from the hardening process of the concrete.

  According to a second aspect of the present invention, when the inner mold frame is assembled in an annular shape inside the tail portion, the inner mold frame is inserted into the frame of the inner mold frame via one side portion of the slit opened in the inner mold frame. The first strain gauge is incorporated into the concrete placement space side so as to be pushed out, and the second strain gauge is incorporated into the concrete placement space side through the other side of the slit so as to be pushed out. Since the first strain gauge and the second strain gauge are pushed in with different depths, the first strain gauge and the second strain gauge are added in addition to the effect of the invention of claim 1. The strain applied to the inside of the lining concrete constructed by the ECL method can be embedded in the placed concrete relatively close to the circumferential direction and embedded at different indentation depth positions. Concri DOO continuously and reliably from the curing process, there is an advantage that can be measured in detail.

  According to a third aspect of the present invention, a plurality of strain gauges are incorporated in the inner mold frame assembled in an annular shape at appropriate intervals in the circumferential direction, and the plurality of strain gauges are installed In addition to the effect of the invention according to claim 1 or 2, in addition to the effect of the invention according to claim 1 or 2, the above-mentioned plurality of strain gauges are used at each location over the entire circumference including the top and bottom of the placed concrete. The internal strain can be measured, and there is an advantage that the strain applied to the inside of the lining concrete constructed by the ECL method can be continuously and reliably measured from the hardening process of the concrete.

  The invention according to claim 4 is a strain gauge attached to the tip of the push rod at a portion in the frame of the inner mold facing the slit opened in the frame on the concrete placement space side in the inner mold, A ball screw shaft and a drive element screwed to be movable in the axial direction of the ball screw shaft in a state where the rotation of the ball screw shaft is restricted, and a rear end portion of the push rod is screwed, Equipped with a ball screw unit that is detachably attached to the inner mold side, and the strain gauge is pushed through the slit by driving the ball screw shaft into the placed concrete. The strain gauge can be securely embedded at the required indentation depth position in the placed concrete, and the strain applied to the inside of the lining concrete constructed by the ECL method is applied to the concrete. It can be continuously more reliably measured from Process. Moreover, after embedding the strain gauge, the entire ball screw unit can be removed from the inner mold frame side, and the ball screw unit protruding from the inner mold frame does not interfere with other operations in the mine. There is an advantage.

  According to the fifth aspect of the present invention, the first push rod is attached to a portion of the inner mold frame facing one side of the slit opened in the frame plate on the concrete placement space side of the inner mold frame. The first strain gauge attached to the tip, the first ball screw shaft, and the first ball screw shaft can move in the axial direction of the first ball screw shaft in a state in which the rotation is restricted. A first ball screw unit screwed and provided with a first driver element screwed at a rear end of the first push rod, and detachably attached to the inner mold side; A second strain gauge attached to the tip of the second push rod that is shorter than the first push rod is provided in a portion of the inner mold frame facing the other side of the slit. , A second ball screw shaft shorter than the first ball screw shaft, and the second A second driver element screwed into the second ball screw shaft so as to be movable in the axial direction in a state where the rotation of the ball screw shaft is restricted, and a rear end portion of the second push rod being screwed. And a second ball screw unit that is detachably attached to the inner formwork side, and the first ball screw shaft is driven into the placed concrete to drive the first ball screw shaft. By pushing a strain gauge through one side part of the slit and driving the second ball screw shaft, the second strain gauge is pushed through the other side part of the slit. The first strain gauge and the second strain gauge are relatively close to each other in the circumferential direction, and the second strain is applied. Each meter is shallower than the first strain gauge And it can be embedded respectively and included depth position, the strain applied to the interior of the lining concrete constructed in ECL method continuously and reliably from the curing process of the concrete can be measured in detail. Moreover, after embedding the first and second strain gauges, the entire first and second ball screw units can be removed from the inner mold frame side, and the first and second protruding from the inner mold frame can be obtained. The ball screw unit has the advantage that it does not interfere with other operations in the mine.

  According to a sixth aspect of the present invention, a sensor case is detachably attached to a portion in the frame of the inner mold facing the slit opened in the frame plate on the concrete placement space side in the inner mold, and the push rod Is inserted into the bottom plate of the sensor case movably, and the strain gauge is attached to the tip of the push rod in the sensor case, in addition to the effects of the invention of claim 4 or 5, Even if the concrete placed in the concrete placement space enters the slit, the concrete is stopped in the sensor case and does not leak into the frame of the inner mold. In addition, after embedding the strain gauge in the concrete, the sensor case can be removed from the inside of the inner formwork frame, and the sensor case is pulled out from the push rod or strain gauge when the inner formwork is removed. There is an advantage that they do not come into contact with cables or the like and cause damage to them.

  For the purpose of continuously and reliably measuring the strain applied to the inside of the lining concrete constructed by the ECL method from the hardening process of the concrete, a slit is opened in the frame plate on the concrete placement space side in the measurement inner mold, A first strain gauge attached to the tip of the first push rod, a first ball screw shaft, and the first ball screw shaft at a portion in the frame of the measurement inner mold that faces one side of the slit A first driver element screwed so as to be movable in the axial direction of the first ball screw shaft in a state in which the rotation of the ball screw shaft is restricted, and a rear end portion of the first push rod being screwed. And a first ball screw unit that is detachably attached to the measurement inner formwork side, and a part in the frame of the measurement inner formwork facing the other side portion of the slit includes the first ball screw unit. Second pusher shorter than pusher rod 1 The second strain gauge attached to the tip of the insert rod, the second ball screw shaft shorter than the first ball screw shaft, and the state in which the rotation is restricted by the second ball screw shaft And a second driver element screwed so as to be movable in the axial direction of the second ball screw shaft and having a rear end portion of the second push rod screwed thereto, and is removed from the measurement inner mold side. And a second ball screw unit that is detachably mounted, and the first strain gauge is driven through one side of the slit by driving the first ball screw shaft in the cast concrete. The second strain gauge is driven to the shallower depth position than the first strain gauge through the other side of the slit by driving the second ball screw shaft. , Filling of first and second strain gauges After viewing was achieved by removing the first and second ball screw unit from measuring the mold side.

  Embodiment 1 of the present invention will be described below in detail with reference to the drawings. FIGS. 1-4 is a figure which shows the internal mold form in which the measuring apparatus of the internal strain which concerns on a present Example was integrated. 5 to 7 are enlarged views showing the configuration of the internal strain measuring device, and FIG. 8 is a view showing the vicinity of the tail portion of the shield excavator in which the inner mold is incorporated. The internal strain measuring apparatus according to the present embodiment is used as a strain gauge even when a wife form inner peripheral seal passes over the frame plate on the concrete placement space side in the measurement form before the concrete is placed. In order to prevent damage, when the measurement inner mold is assembled in an annular shape inside the tail part of the shield excavator, it is incorporated into the frame of the measurement inner mold reserved from the concrete placing space side. . Then, a strain gauge is pushed in and embedded in the placed concrete through a slit opened in the frame plate of the measurement inner mold, and the internal strain of the concrete is measured from the hardening process.

  First, the configuration of the internal strain measuring device according to the present embodiment will be described. As shown in FIGS. 1 to 4, among the inner molds assembled in an annular shape, the circumferential direction is placed on the face side of the frame plate of the measurement inner mold 2 a in which the internal strain measuring device 1 is incorporated. A rectangular slit 3 in the longitudinal direction is opened. As shown in FIGS. 5 and 6 in an enlarged manner, the slit 3 has the opening portion of the sensor case 4 having the same shape as the slit 3 inserted from the inner side of the measurement inner mold 2a. The sensor case 4 is fixed in the frame of the measurement inner mold 2a by tightening the bolts 5 and 5 at the flange portion.

  On the lower surface side of the sensor case 4, a first restricting member 6 composed of two long plates 6b, 6b extending downward from one side of one mounting plate 6a and the first restricting member 6a. Except for the point shorter than the member 6, the 2nd control member 7 comprised similarly to this 1st control member 6 and extended below from the other side part of the attachment board 6a is arrange | positioned. . The first restricting member 6 and the second restricting member 7 are fixed to the lower surface of the sensor case 4 by tightening bolts 8 and 8 at the attachment plate 6a.

  The first restricting member 6 includes two first push rods 9, 9 that are movably fitted to the bottom plate and the attachment plate 6 a of the sensor case 4, and the longitudinal length of the first restricting member 6. Arranged along the direction. The tip portions of the two first push rods 9 and 9 are located in the sensor case 4, and the first strain gauge support member 10 is fixed to the tip portions by screws. As shown in FIGS. 7A and 7B, a first strain gauge 13 is mounted on the first strain gauge support member 10 by a U-shaped support tool 11 and bolts 12a and nuts 12b. The cable 14 attached and led out from the first strain gauge 13 is attached by a support 15 having a U-shaped section and two sets of bolts 16a and nuts 16b. As described above, the first strain gauge 13 is mounted on the first strain gauge support member 10 in the sensor case 4.

  In the portion of the second restricting member 7, two second push rods 17, 17 shorter than the first push rod 9 are arranged along the longitudinal direction of the second restricting member 7. Has been. The two second push rods 17 and 17 are movably fitted into the bottom plate of the sensor case 4 and the mounting plate 6a, and the distal ends of the push rods 17 and 17 are located in the sensor case 4. Yes. A second strain gauge support member 18 is fixed to the distal ends of the two second push rods 17 and 17 by screwing. On the second strain gauge support member 18, the second strain gauge 19 and the cable 20 led out from the second strain gauge 19 have a cross section similar to the first strain gauge support member 10 side. It is attached by a U-shaped support and bolts and nuts. As described above, the second strain gauge 19 is mounted on the second strain gauge support member 18 in the sensor case 4.

  A first ball screw shaft 21 is disposed at a substantially intermediate position between the two first push rods 9. The front end portion of the first ball screw shaft 21 is rotatably supported by the bottom plate of the sensor case 4 and the mounting plate 6a, and the rear end portion is the two long plates 6b of the first regulating member 6, The support plate 22 fixed to the inward flange portion 6b is rotatably supported. A first driver 23 is screwed onto the first ball screw shaft 21. When the first ball screw shaft 21 is rotated, the first driver element 23 is in a state where the rotation is restricted by the two long plates 6b and 6b in the first restricting member 6. One ball screw shaft 21 is moved in the axial direction, and the rear ends of the two first push rods 9 and 9 are connected to the first driver 23 with screws 24 and 24, respectively. Installed by tightening. The first restricting member 6, the first ball screw shaft 21 and the first driver 23 constitute a first ball screw unit 25.

  Further, a second ball screw shaft 26 shorter than the first ball screw shaft 21 is disposed at a substantially intermediate position between the two second push rods 17 and 17. The front end of the second ball screw shaft 26 is rotatably supported by the bottom plate and the mounting plate 6a of the sensor case 4, and the rear end is fixed to the rear end of the second restricting member 7. The support plate 27 is rotatably supported. A second driver element 28 is screwed onto the second ball screw shaft 26. When the second ball screw shaft 26 is rotated, the second driver element 28 moves on the second ball screw shaft 26 in a state where the rotation is restricted by the second restriction member 7. The rear end of the two second push rods 17, 17 is attached to the second driver element 28 by tightening screws 29, 29. The second restriction member 7, the second ball screw shaft 26 and the second driver element 28 constitute a second ball screw unit 30.

  The internal strain measuring device 1 including the first and second strain gauges 13 and 19 and the first and second ball screw units 25 and 30 is a ring (annular ring) of the measurement inner mold 2a. About 8 units are incorporated at regular intervals. Moreover, the ring (ring) of the measurement inner mold 2a is incorporated every several tens of meters with respect to the traveling direction of the shield excavator.

  As shown in FIG. 8, the shield excavator includes an inner mold 2, a measurement inner mold 2 a, an inner mold 2,. Take the reaction force and move forward. At this time, the end frame inner peripheral seal 33 attached to the lower side of the endless frame jack 32 also serving as a concrete injection nozzle passes while sliding on the frame plate on the concrete placing space 34 side in the measurement inner frame 2a. . On the other hand, the internal strain measuring device 1 is the first even if the end mold inner peripheral seal 33 passes over the frame plate on the concrete placing space 34 side in the measurement inner form 2a before placing concrete. In order to prevent the second strain gauges 13 and 19 from being damaged, when the measurement inner form 2a is assembled in an annular shape inside the tail part of the shield excavator, the measurement is kept from the concrete placement space 34 side. It is incorporated in the frame of the mold 2a.

  Next, a method for measuring the internal strain of the lining concrete by the internal strain measuring device 1 configured as described above will be described with reference to FIGS. Each figure is a figure for demonstrating the pushing procedure of the strain gauge in the cast concrete.

  After the wife form inner peripheral seal 33 passes over the frame plate on the concrete placement space 34 side in the measurement inner form 2a, the wife form jack 32 also serving as a concrete injection nozzle enters the concrete placement space 34. The concrete 35 is placed under pressure. At this time, even if the placed concrete 35 enters the slit 3, the concrete 35 is stopped in the sensor case 4 and does not leak into the frame of the measurement inner mold 2a (FIG. 9).

  After placing the concrete 35, the first strain gauge 13 is driven by the first driver 23 from one side of the slit 3 by rotating the first ball screw shaft 21. It is embedded at a required indentation depth position in the provided concrete 35. Further, by rotating the second ball screw shaft 26, the second strain gauge 19 is driven by the second driver element 28, and the first strain gauge 13 from the other side of the slit 3. It is embedded at the required depth of indentation. As a result, the first strain gauge 13 and the second strain gauge 19 are relatively close to each other in the circumferential direction in the placed concrete 35 and each required indentation depth position is different. (FIG. 10).

  After the first and second strain gauges 13 and 19 are embedded in the concrete 35, the bolts 8 and 8 fixing the first and second restricting members 6 and 7 to the lower surface of the sensor case 4 are tightened back. , Tightening back the screws 24, 24 fixing the rear ends of the two first push rods 9, 9 to the first driver 23, and the two second push rods 17, 17. Screws 29, 29 fixing the rear end of the second driver element 28 to the second driver element 28 are tightened to separate the first and second ball screw units 25, 30 from the lower surface of the sensor case 4. Preparation is performed (FIG. 11).

  Next, by pulling the first and second ball screw units 25, 30, the first and second ball screw units 25, 30 are moved to the two first push rods 9, 9, 2. The second push rods 17 and 17 and the sensor case 4 are separated and removed, and a procedure is performed so as not to interfere with other operations in the mine (FIG. 12).

  Thereafter, the bolts 5 and 5 fixing the sensor case 4 in the frame of the measurement inner mold 2a are tightened, and the sensor case 4 is removed from the frame of the measurement inner mold 2a. . The sensor case 4 is removed around the first day when the first and second strain gauges 13 and 19 are embedded in the placed concrete 35. Thus, by removing the sensor case 4 together with the removal of the first and second ball screw units 25 and 30, the two first pieces are respectively removed when the next inner mold frame 2 a is removed. The sensor case 4 does not come into contact with the push rods 9, 9, the second push rods 17, 17, and the two cables 14, 20 to cause damage (FIG. 13).

  After the sensor case 4 is removed, the measurement inner mold 2a is removed from the concrete 35. This demolding is carried out around the second day after the first and second strain gauges 13 and 19 are embedded in the placed concrete 35 (FIG. 14). FIG. 15 shows a cross section taken along the line CC in FIG. Thereafter, as described above, the internal strain is continuously measured from the hardening process of the concrete 35 by the first and second strain gauges 13 and 19 embedded in the concrete 35.

  As described above, in the measuring method and measuring apparatus for internal strain in lining concrete by the ECL method according to the present embodiment, the first strain gauge 13 and the second strain gauge 19 are placed in the concrete 35 in which the first strain gauge 13 is placed. In addition, the second strain gauge 19 can be embedded at each required push-in depth position relatively close to the circumferential direction and shallower than the first strain gauge 13. Therefore, the strain applied to the inside of the lining concrete constructed by the ECL method can be measured continuously and reliably from the hardening process of the concrete 35.

  Even if the concrete 35 placed in the concrete placement space 34 enters the slit 3, the concrete 35 is stopped in the sensor case 4 and does not leak into the frame of the measurement inner mold 2a.

  Further, after the first strain gauge 13 and the second strain gauge 19 are embedded, the first ball screw unit 25, the second ball screw unit 30, and the sensor case 4 are removed from the frame of the measurement inner mold 2a. Thus, the first ball screw unit 25 and the second ball screw unit 30 protruding from the measurement inner mold 2a do not interfere with other work in the mine. Further, the sensor case 4 comes into contact with the two first push rods 9, 9 and the second push rods 17, 17 and the two cables 14, 20 when the inner mold 2a is removed. Thus, they are not damaged.

  The present invention can be variously modified without departing from the spirit of the present invention, and the present invention naturally extends to the modified ones.

The figure shows an embodiment of the present invention.
The partially cutaway front view of the internal strain measuring device incorporated in the frame of the inner mold. The top view of FIG. The bottom view of FIG. Sectional drawing in alignment with the AA of FIG. The enlarged front view of the internal strain measuring device. Sectional drawing which follows BB of FIG. (A) and (b) are the enlarged side views of a strain gauge support part and a cable support part. The side view which shows the tail part vicinity of the shield excavator in which the inner formwork provided with the measuring apparatus of an internal strain was integrated. The figure for demonstrating the pushing procedure of the strain meter into the cast concrete. The figure for demonstrating the pushing procedure of the strain meter into the cast concrete. The figure for demonstrating the pushing procedure of the strain meter into the cast concrete. The figure for demonstrating the pushing procedure of the strain meter into the cast concrete. The figure for demonstrating the pushing procedure of the strain meter into the cast concrete. The figure for demonstrating the pushing procedure of the strain meter into the cast concrete. It is a figure for demonstrating the pushing procedure of the strain gauge in the placed concrete, and sectional drawing which follows the CC line of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal strain measuring device 2 Inner mold 2a Measurement inner mold 3 Slit 4 Sensor case 6 1st control member 7 2nd control member 9 1st push rod 13 1st strain gauge 17 2nd push rod 19 Second Strain Meter 21 First Ball Screw Shaft 23 First Driver 25 First Ball Screw Unit 26 Second Ball Screw Shaft 28 Second Driver 30 Second Ball Screw Unit 32 Concrete Injection Nozzle Combined wife frame jack 33 Wife form inner circumference seal 34 Concrete placement space 35 Concrete

Claims (6)

While excavating a tunnel with a shield excavator, an inner mold is assembled in an annular shape inside the tail part of the shield excavator, and a concrete placement space formed between the inner mold and the excavated natural ground is formed. It is a method for measuring internal strain in lining concrete by ECL method that constructs lining concrete by placing concrete directly,
When the inner mold frame is assembled in an annular shape inside the tail part, a strain gauge is incorporated into the inner mold frame so that it can be pushed out to the concrete placement space side through a slit opened in the inner mold frame. The method of measuring internal strain in lining concrete by ECL method, wherein the strain gauge is pushed into the placed concrete.   When the inner mold frame is assembled in an annular shape inside the tail portion, it can be pushed out into the concrete placement space side through one side of the slit opened in the inner mold frame in the inner mold frame. The first strain gauge is incorporated in the concrete and the second strain gauge is incorporated into the concrete placement space through the other side of the slit, and the first strain gauge is incorporated in the placed concrete. The method of measuring internal strain in lining concrete by the ECL method according to claim 1, wherein the first strain gauge and the second strain gauge are pushed in at different depths.   Incorporating a plurality of strain gauges at appropriate intervals in the circumferential direction into the frame of the inner mold assembled in the annular shape, and pushing the plurality of strain gauges into the placed concrete, respectively. A method for measuring internal strain in lining concrete by the ECL method according to claim 1 or 2. While excavating a tunnel with a shield excavator, an inner mold is assembled in an annular shape inside the tail part of the shield excavator, and a concrete placement space formed between the inner mold and the excavated natural ground is formed. A device for measuring internal strain in lining concrete by ECL method, in which concrete is placed directly to construct lining concrete,
A strain gauge attached to the tip of the push rod, a ball screw shaft, and the ball at a portion in the frame of the inner mold frame facing a slit opened in the frame plate on the concrete placement space side in the inner mold frame The screw shaft is provided with a driver element that is screwed so as to be movable in the axial direction of the ball screw shaft in a state in which the rotation is restricted, and the rear end portion of the push rod is screwed. An ECL method characterized by comprising a ball screw unit that is detachably mounted, and driving the ball screw shaft into the placed concrete so as to push the strain gauge through the slit. A device for measuring internal strain in lining concrete.   A first attached to the tip portion of the first push rod at a portion in the frame of the inner mold facing one side of the slit opened in the frame plate on the concrete placement space side in the inner mold. The first ball screw shaft and the first ball screw shaft in a state in which the rotation is restricted so as to be movable in the axial direction of the first ball screw shaft. And a first ball screw unit that is detachably attached to the inner mold side, and includes a first driver screw that is screwed to the rear end of the push rod. A portion in the frame of the inner mold facing the second strain gauge attached to the tip of the second push rod shorter than the first push rod, and the first ball screw shaft The second ball screw shaft having a shorter dimension and the second ball screw shaft can be rotated. A second driver element screwed in a restrained state so as to be movable in the axial direction of the second ball screw shaft and having a rear end portion of the second push rod screwed thereto; A second ball screw unit detachably attached to the side, and driving the first ball screw shaft into the placed concrete, the first strain gauge is placed in the slit. Pushing through the side part and driving the second ball screw shaft causes the second strain gauge to be pushed through the other side part of the slit to a shallower depth position than the first strain gauge. The apparatus for measuring internal strain in lining concrete by the ECL method according to claim 4, wherein the apparatus is pushed into the concrete.   A sensor case is detachably attached to a part of the inner mold frame facing the slit opened in the frame plate on the concrete placement space side of the inner mold frame, and the push rod moves to the bottom plate of the sensor case. 6. The apparatus for measuring internal strain in lining concrete by the ECL method according to claim 4, wherein the strain gauge is freely inserted and attached to the tip of the push rod in the sensor case. .

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