JP6304527B2 - Tunnel rock exploration method - Google Patents

Description

The present invention relates to a tunnel ground exploration method .

  It is particularly important to confirm and grasp the conditions of the surrounding rocks with high accuracy in order to safely proceed with tunnel construction and to carry out necessary construction work such as necessary reinforcements accurately and promptly. Conventionally, as methods for confirming and grasping the condition of ground around the tunnel, methods for directly confirming and grasping ground conditions such as drilling holes and advanced boring, and indirect land by various physical exploration A technique for confirming and grasping the mountain situation is used (see, for example, Patent Document 1, Patent Document 2, and Patent Document 3).

JP2013-2092A JP 2012-12879 A JP 2010-230689 A

  However, in the conventional method of confirming and grasping the condition of the surrounding rock ground except for the exploration hole, the tunnel construction must be temporarily interrupted, so the fault can be improved by proceeding with the tunnel excavation. This is often done to investigate the cause after some bad ground condition appears, such as in the case that the tunnel deformation after excavation does not converge.

  For this reason, the said conventional method will start the preparation after a certain trouble arises with respect to construction, and time is required in order to obtain a result. It should be noted that it is not reasonable in terms of cost to prepare the conventional method in advance even though there is no bad ground condition.

In view of the above circumstances, the present invention continuously monitors the ground conditions in normal construction management and grasps in advance the possibility of occurrence of abnormalities, thereby rationally determining whether or not to conduct a detailed survey. An object of the present invention is to provide a tunnel ground exploration method capable of shortening the time required for obtaining the ground exploration result while proceeding and preparing in advance for confirmation survey.

  In order to achieve the above object, the present invention provides the following means.

The tunnel ground exploration method of the present invention monitors the drilling status of a plurality of rock bolts to be driven from a pit wall to a ground, and receives a plurality of the rock bolts to be subjected to vibration receiving probes and The first exploration process to grasp the ground condition behind the well wall by the refraction elastic wave exploration method used as an oscillating probe, and an excavator that excavates the face using a plurality of placed rock bolts as receiving probes And a second exploration step for grasping the ground condition in front of the face by a reflection elastic wave exploration method using as an oscillation source, and the first exploration step, when drilling a rock bolt placement hole, While monitoring the drilling situation, arranging the records obtained in this monitoring process in the longitudinal direction of the tunnel, plotting the change point of the measured value along the pit wall, and while the excavation work is stopped, Drilling progressed Recorded data obtained by the refraction method elastic wave exploration method using a plurality of rock bolts as receiving probe and oscillation probe for the gap, and the elastic wave receiving sensor attached to the lock bolt And a step of estimating the velocity structure behind the tunnel wall along the tunnel, and the second exploration step includes a step of performing a reflection elastic wave exploration using a blow at the time of shaping of the face and the tunnel wall as a vibration source, Based on the reflection waveform obtained by analyzing the recording data of the reflection method acoustic wave exploration process, the change point of the ground condition where the reflected wave is generated from the comparison between the situation of moving with excavation and the face position A step of estimating the position of the ground, and repeatedly performing a search for a slack area in the back of the pit wall and a search for a defective portion in front of the face in the normal construction cycle by the first search step and the second search step. It is characterized by that.

In the tunnel ground exploration method of the present invention, it has been possible to carry out a series of operations to search the slack area behind the well wall and the front face of the face, which were conventionally performed individually, and continuously performed according to the progress of construction. By doing so, it becomes possible to continuously monitor the condition of natural ground around the tunnel.

  As a result, it is possible to detect a thick part of the slack area and a defective part of the ground in front of the face and contribute to a rational judgment as to whether or not to conduct a more detailed detailed survey such as advanced boring. In some cases, it is possible to arrange for countermeasure work in advance, and the construction process can be shortened.

Therefore, according to the tunnel ground exploration method of the present invention, by monitoring the ground state continuously during normal construction management and grasping in advance the possibility of occurrence of abnormalities, While making reasonable decisions, preparations for confirmation surveys can be made in advance, and it is possible to shorten the time required to obtain ground survey results.

  In addition, since it is a series of systems combined so that it can be carried out continuously even during normal construction management, it is necessary to conduct detailed surveys by grasping ground conditions without interrupting construction and capturing signs of changes. This makes it possible to provide a reasonable basis for determining the implementation point.

It is a flowchart which shows the tunnel ground exploration system (tunnel ground exploration method) which concerns on one Embodiment of this invention. It is a figure which shows an example of the plot of the drilling condition record of the drilling hole of the rock bolt in the tunnel ground exploration system (tunnel ground ground exploration method) which concerns on one Embodiment of this invention, and evaluation of the ground state behind a well wall. is there. It is a figure which shows the state which installed the lock bolt protective cover in the head side of the lock bolt. FIG. 4 is a view taken along line X1-X1 in FIG. 3. It is a figure which shows the procedure which explores the ground condition in the depths of a mine wall, using a rock bolt as a probe for vibration and a probe for oscillation. It is a figure which shows the state which installed the sensor for elastic wave vibration reception and the sensor protection cover in the head side of the lock bolt. It is a perspective view which shows a sensor protective cover. It is a figure which shows the procedure which searches the ground condition ahead of a face, using a rock bolt as a probe for vibration reception, and using a face excavator as an oscillation source.

Hereinafter, a tunnel ground exploration system (tunnel ground ground exploration method) according to an embodiment of the present invention will be described with reference to FIGS. Here, this embodiment is a series of systems combined so that it can be continuously carried out even during normal construction management, by grasping the ground conditions without interrupting construction and by capturing signs of the change The present invention relates to a tunnel ground exploration system (tunnel ground exploration method) that makes it possible to provide a rational basis for the necessity of detailed surveys and the determination of the implementation point.

  First, as shown in FIG. 1, the tunnel ground exploration system A of this embodiment is a means for confirming and grasping the situation of the ground around the tunnel G in the construction cycle by the NATM construction method for constructing the tunnel T. , The first exploration means 1 (first exploration process) for monitoring and confirming and grasping the change in the ground condition in the slack area behind the mine wall T1, and the condition of the ground condition in the defective ground area in front of the face T2 It comprises a second exploration means 2 (second exploration process) for monitoring, confirming and grasping changes.

  In the tunnel ground exploration system A of the present embodiment, the first exploration means and the second exploration means are used to search for a slack area behind the pit wall T1 and to search for a bad place in front of the face T2. Repeat in the cycle.

  Specifically, in the tunnel ground exploration system A of the present embodiment, as shown in FIG. 1, first, a procedure for exploring the ground state behind the well wall T1 by the first exploration means 1 (first exploration step) ( As 1), when the drilling hole of the rock bolt of the well wall T1 supporting work that is a constituent element of the first exploration means 1 is drilled, the drilling condition is monitored (rock bolt drilling condition monitoring step).

  Here, a drilling logging device is attached to a drilling jumbo for drilling, and the drilling speed, drilling energy (calculated from drill feed pressure, torque pressure, etc.), etc. are measured and recorded by this drilling logging device. In this embodiment, as shown in FIG. 1 and FIG. 2, the target lock bolts 3 are basically located on the left and right side walls and the top end of the tunnel T. Bolts 3 may be added to the target or the number may be reduced. If it is difficult to attach a relatively expensive drilling logging device, it is sufficient that the drilling speed can be recorded at a minimum.

  Next, in the procedure (2) by the first exploration means 1, as shown in FIGS. 1 and 2, the records obtained in the procedure (1) are arranged in the longitudinal direction of the tunnel, and the measured value changes along the tunnel wall T1. Points are plotted (drilling data plotting step). In general, since the drilling speed and drilling energy reflect the strength of the natural ground G, the shallow depth of these change points corresponds to the depth of the loose region. In addition, if there is a rock mass degradation part such as a fault, a particularly large change will appear at that location.

  And, for example, as shown in FIG. 2, when excavation progresses by about 50 m and data is accumulated, while excavation work is stopped, such as shift time for day and night work, as the procedure (3) by the first exploration means 1, A refraction elastic wave exploration method for the advanced section is carried out (refractive elastic wave exploration process).

  In this embodiment, in this procedure (3), as shown in FIG. 6, the elastic wave receiving sensors 4, 5 as the first exploration means 1 are attached to the head of the lock bolt 3, and the lock bolt 3 itself is received. Use as a probe for vibration (spike for receiving vibration). This is because the vibration transmitted through the inner wall of the mine wall T1 is received to improve the search accuracy, and the work for attaching the elastic wave receiving sensors 4 and 5 can be performed easily. Further, the elastic wave receiving sensors 4 and 5 may be attached by magnets or the like, for example, Japanese Patent Application No. 2013-055216 “Vibration sensor mounting tool” by the present applicant may be used. The elastic wave receiving sensors 4 and 5 are preferably attached to the lock bolts 3 in the same arrangement as that obtained in step (1).

  Next, in this embodiment, the oscillation of the elastic wave in the procedure (3) is performed at the same position as the installation point of the elastic wave receiving sensors 4 and 5 in the same manner as in the conventional refraction elastic wave exploration method.

  Specifically, the elastic wave receiving sensors 4 and 5 are once removed, and the head of the lock bolt 3 is hit with a hammer or a hanging arrow to oscillate. At this time, as shown in FIGS. 3 and 4, a metal detachable lock bolt protective cover 7 is attached to the head of the lock bolt 3, and a lock is applied from above the lock bolt protective cover 7. Prevents the bolt 3 from being damaged. The lock bolt protection cover 7 is formed so as to contain the head of the lock bolt 3 and the lock bolt nut 3a, and is screwed into the lock bolt nut 3a to be tightened by screwing the bolt 6, thereby protecting the lock bolt. The cover 7 is configured to be detachably fixed.

  Then, as shown in FIGS. 1 and 5, at the stage where the oscillation operation is completed in this way, the elastic wave receiving sensors 4, 5 are attached, and the elastic wave receiving sensors 4, 5 are installed by the adjacent lock bolt 3. The lock bolt protective cover 7 is attached and the next oscillation is performed, and the oscillation work is sequentially performed on all the target lock bolts 3. That is, the refraction method elastic wave exploration method is carried out using the lock bolt 3 as a vibration exploration probe and an oscillation exploration probe.

  The vibration detected by the elastic wave receiving sensors 4 and 5 is recorded by a data logger (measurement / recording meter) connected to the elastic wave receiving sensors 4 and 5 by wire or wirelessly, and further recorded from the data logger to a personal computer. The Then, as shown in FIG. 1, in the step (4), the recorded data is analyzed by a so-called “stripping method” or tomography method in the same manner as in the existing refracting elastic wave exploration method, The speed structure behind the wall T1 is estimated (the natural ground speed structure analysis step). At this time, the change rate distribution of the drilling speed and drilling energy obtained in the procedure (2) is used as the foresight information in comfort to improve the analysis accuracy.

  When the oscillation in all the rock bolts 3 in the target section is completed, in preparation for the next excavation work, as the procedure (5), the elastic wave receiving sensors 4 and 5 from the working face T2 to the construction method section are removed, As shown in FIGS. 6 and 7, a sensor protective cover 8 is attached to the remaining acoustic wave receiving sensors 4 and 5 in order to prevent flying stones at the time of blasting and mortar splashing at the time of spraying. The sensor protective cover 8 is a metal detachable cover and is formed so as to include the head of the lock bolt 3 and the elastic wave receiving sensors 4 and 5. In addition, the sensor protective cover 8 of the present embodiment is formed by opening a part of one of the four side surfaces, for example, and the state of the elastic wave receiving sensors 4 and 5 can be visually confirmed through the opening. It is formed so that wiring can be easily connected.

  On the other hand, as shown in FIG. 1 and FIG. 8, a ground failure location in front of the face T 2 is searched by the second search means 2 (second search step) of the tunnel ground check system A of the present embodiment. The second exploration means 2 searches for an unsatisfactory site in front of the face T1 in the reflection elastic wave exploration using the strike of the breaker 9 used when shaping the face T2 and the pit wall T1 as a vibration source. (Reflecting elastic wave exploration process: see, for example, Japanese Patent Application No. 2011-231920 by the present applicant). As a procedure (6) by the second exploration means 2, the measurement is performed about once a day in principle. However, the elastic wave receiving sensors 4 and 5 are not moved every time the excavation progresses, and the excavation is about 20 to 30 m. Keep it in the same position until you advance. However, as shown in FIG. 8, when vibration attenuation is significant due to ground conditions, the sensor moves forward at any time while maintaining the sensor interval.

  The vibration detected by the elastic wave receiving sensors 4 and 5 is recorded by the same data logger 10 and the personal computer 11 used in the procedure (4), and the recorded data is analyzed by a method according to the existing reflection elastic wave exploration. To do. And as a procedure (7), based on the reflection waveform obtained by the analysis, the situation of the ground condition where the reflected wave is generated from the comparison between the situation where the excavation progresses about 20 to 30 m and the face position. Estimate the position of the change point. Furthermore, in this embodiment, in the vibration analysis of the procedure (7), the ground condition around the tunnel wall T1 estimated by the procedure (4) is utilized as foresight information.

  When drilling the lock bolt 3 to be newly placed while excavation proceeds, the procedure (1) and the procedure (2) are performed. When the face T2 has traveled about 20 to 30 m, as a procedure (8), the elastic wave receiving sensors 4 and 5 removed when excavation is stopped at the time of work shift or the like are reattached immediately after the face and the remaining elastic wave receiving sensor is left. 4 and 5 are moved forward, and step (3) and step (4) are performed. Thereafter, the above operation is repeated.

  Therefore, in the tunnel ground exploration system A of the present embodiment, the loose area exploration behind the well wall T1 and the exploration in front of the face T2 that have been conventionally performed can be performed in a series of operations, and the progress of construction can be achieved. By carrying out continuously, it becomes possible to continuously monitor the situation of the natural ground G around the tunnel T.

  As a result, it is possible to detect a thick part of the slack area and an unsatisfactory part in front of the face T2 and contribute to a rational judgment as to whether or not to conduct a more direct detailed investigation such as advanced boring. In some cases, it is possible to arrange for countermeasure work in advance, and the construction process can be shortened.

  In addition, the equipment to be used is not special in both oscillation and vibration, and commercially available relatively inexpensive equipment can be commonly used as the first exploration means 1 and the second exploration means 2.

  Therefore, according to the tunnel ground exploration system A of the present embodiment, the detailed survey is carried out by continuously monitoring the ground state during normal construction management and grasping in advance the possibility of anomalies. It is possible to rationally proceed with the determination of availability, and to make preparations for confirmation surveys in advance, thereby shortening the time required to obtain the ground survey results.

  In addition, since it is a series of systems combined so that it can be carried out continuously even during normal construction management, it is necessary to conduct detailed surveys by grasping ground conditions without interrupting construction and capturing signs of changes. This makes it possible to provide a reasonable basis for determining the implementation point.

Although one embodiment of the tunnel ground exploration method according to the present invention has been described above, the present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 1st exploration means 2 2nd exploration means 3 Rock bolt 3a Lock bolt nut 4 Elastic wave receiving sensor 5 Elastic wave receiving sensor 6 Bolt 7 Lock bolt protective cover 8 Sensor protective cover 9 Breaker 10 Data logger 11 Personal computer A Tunnel ground Mountain exploration system G Ground mountain T Tunnel T1 Well wall T2 Face

Claims (1)

Refraction method elasticity that monitors the drilling status of multiple rock bolts to be drilled from the pit wall to the ground and uses the multiple rock bolts to be used as a vibration probe and oscillation probe A first exploration process to grasp the ground conditions behind the mine wall by the wave exploration method;
A second exploration step of grasping ground conditions in front of the face by a reflection elastic wave exploration method using a plurality of placed rock bolts as a vibration probe and receiving an excavator for excavating the face as an oscillation source ;
In the first exploration process, when drilling the drill hole of the rock bolt, the drilling condition is monitored, and the records obtained in this monitoring process are arranged in the tunnel longitudinal direction and measured along the tunnel wall. Refraction method elastic wave using a plurality of rock bolts as receiving probe and oscillation probe for plotting change point of value and section where excavation progressed while excavation work stopped A step of performing an exploration method, and a step of estimating a velocity structure behind the tunnel wall along the tunnel based on recorded data obtained by an elastic wave receiving sensor attached to a rock bolt,
In the second exploration step, the reflection method elastic wave exploration is performed using the impact at the time of shaping the face and pit wall as a source, and the reflection data obtained by analyzing the record data of the reflection method elastic wave exploration step is analyzed. Based on the waveform, from the comparison between the situation of moving with excavation progress and the face position, the step of estimating the position of the change point of the ground condition where a reflected wave occurs,
A tunnel ground exploration method characterized by repeatedly performing a search for a slack area in the back of a pit wall and a search for a defective ground in front of a face in a normal construction cycle by the first exploration step and the second exploration step. .

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