JP2003314196A - Method for predicting natural ground properties ahead of cutting face, and method for excavating natural ground - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for correctly predicting natural ground properties ahead of a cutting face by using excavation data of a TBM. <P>SOLUTION: According to the method, during excavation of the natural ground by the TBM 1, at least one of the factors consisting of cutter torque, thrust force, cutter rotational speed, and cutter intrusion quantity which are required for excavating the natural ground, is collected as the excavation data, and a value indicating the natural ground properties in the cutting face is estimated, followed by comparing the estimated value with a threshold value set beforehand. During the excavation by the TBM 1 over a predetermined distance, if the estimated value indicating the natural ground properties in the cutting face under excavation continuously falls below the threshold value, it is predicted that a fragile layer can be present in front of the cutting face. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for predicting the nature of a rock face in front of a ground and a ground excavation method for excavating the ground by a tunnel boring machine.

[0002]

2. Description of the Related Art Tunnel boring machines (hereinafter referred to as TB
M), while rotating the disk cutter, presses and fixes the gripper against the pit wall, takes reaction force against this, extends the thrust jack, advances the aircraft, and excavates the natural ground. When excavating the ground using this TBM, rapid construction can be expected, but when a fragile stratum such as a fault crush zone is encountered, it may become impossible to excavate due to the collapse of the face. In order to avoid such a situation, accurately predict the rock mass in front of the cutting face, and if it is predicted that there is a fragile layer in front of the cutting face, implement an appropriate front-end construction method to prevent the collapse of the ground mass. It is extremely important to do this.

However, in the TBM, the cutting face is blocked by the TBM machine body as is called a full-section tunnel excavator, and the state of the cutting face cannot be directly observed.
Therefore, as a method of predicting the rock mass properties in front of the face,
For example, as disclosed in Japanese Unexamined Patent Application Publication No. 2002-013381, it is performed to predict a natural rock property in front of a cutting face based on drilling energy required for drilling by a hydraulic rock drill mounted on a TBM. ing.

[0004]

By the way, Japanese Unexamined Patent Application Publication No.
When the technique disclosed in Japanese Patent Publication No. 2-013381 is applied when excavating the ground with TBM, usually 1 per cross section
In many cases, drilling is performed at one place. However, if the fragile portion of the natural ground is distributed irregularly in the unexcavated ground in front of the face, it may be drilled while avoiding the fragile layer, and the existence of the fragile layer cannot be accurately grasped. was there.
On the other hand, if multiple holes are drilled per cross section and the geological exploration in front of the face is to be carried out, not only will it be time-consuming, but also TBM
Could affect the construction cycle of the TBM and sacrifice the advantage of rapid construction of the TBM.

On the other hand, the TBM excavation data such as the cutter torque and thrust thrust obtained during excavation are two-dimensional data in which the natural characteristics of the face of the face are averaged, and have a high correlation with a relatively wide range of natural rock characteristics according to the past research. It is known that there is.
However, these data are often used to evaluate the geological properties in the existing excavated section around TBM,
It has not been applied sufficiently to the geological exploration in front of the cutting face.
An object of the present invention is to accurately predict rock mass properties in front of a cutting face by using excavation data of a TBM, and to prevent a situation in which the TBM enters a fragile layer and makes it impossible to excavate, in front of a cutting face of a tunnel boring machine. To provide a rock mass property prediction method and rock mass excavation method.

[0006]

In order to solve the above-mentioned problems, the invention according to claim 1 uses a face when excavating a natural ground with a tunnel boring machine 1 as shown in FIGS. 1 to 4, for example. A method for predicting rock mass properties in front of a cutting face that predicts rock mass properties in front of the rock face. The threshold value A and the second threshold value B) are set in advance, the tunnel boring machine 1 is excavated, and the cutter torque and thrust required to excavate the ground at the face of the tunnel boring machine 1 during excavation. At least one of thrust, cutter rotation speed, and cutter penetration amount is collected as excavation data, and a value (estimated rock mass strength) indicating the rock mass characteristics of the face under excavation is estimated from the collected excavation data, and this estimation is performed. It And the threshold values A and B are compared with each other to indicate the natural property of the face during excavation, and the estimated face during excavation while the tunnel boring machine 1 excavates a predetermined distance. It is characterized in that if the value indicating the rock mass property in 3 is continuously lower than the threshold values A and B, a fragile layer may exist in front of the face.

According to the first aspect of the present invention, when the tunnel boring machine is advanced, the excavation data required for excavating the ground in the face being excavated is collected, and the excavation data for the face being excavated is collected from the excavation data. The value showing the nature of the ground is estimated. Then, the value indicating the rock mass characteristics of the estimated face is compared with a preset threshold value, and while the tunnel boring machine is excavating a predetermined distance, the ground at the estimated face is estimated. When the value indicating the mountain nature continues to fall below the threshold value, it is predicted that a fragile layer exists in front of the face. Since the above-mentioned excavation data of the face during the excavation collected is obtained from the entire face face having a diameter of 4,5 m, the rock mass in front of the face face is evaluated from the boring hole with a diameter of about 65 mm as in the conventional case. In comparison with the case where it is done, the natural rock property in front of the cutting face is evaluated from the surface data obtained by averaging the natural rock properties. Therefore, even if the fragile layer exists in front of the face in a non-uniform shape, the existence of the fragile layer can be accurately grasped from the surface data, and the boring hole can be drilled as in the past. Since the position where it did not catch the vulnerable layer, the tunnel boring machine did not notice the existence of the vulnerable layer,
There is no possibility of encountering a vulnerable layer and making it impossible to dig.

Further, since excavation data is collected as the tunnel boring machine advances and the threshold value is compared with the estimated value indicating the rock mass characteristics of the face, it is possible that a weak layer in front of the face exists. Whether or not there is can be predicted as the tunnel boring machine is dug. In addition, when the characteristics of the ground are stable, there is no need to stop the excavation and drill a boring hole in order to predict the nature of the ground in front of the cutting face. The construction can be maintained.

According to a second aspect of the present invention, in the method for predicting the nature of a face in front of a face according to the first aspect, as shown in, for example, FIGS. For example, 8 to 10 m) The first threshold value A, which is a value indicating a rock mass characteristic indicating that a fragile layer may exist ahead.
And a position closer to the face than the predetermined distance from the face indicated by the first threshold value A to the fragile layer (for example,
A second threshold value B, which is a value indicating a rock mass property indicating the possibility that a fragile layer exists 3 m ahead of the cutting face), and a value indicating the rock mass property of the estimated cutting face during excavation. Is continuously lower than the thresholds A and B, when the tunnel boring machine 1 excavates when predicting that a fragile layer may exist in front of the face, the first distance is set as the first distance. A first distance corresponding to the threshold value A (for example, 1st: 1.5 m) and a second distance corresponding to the second threshold value B and shorter than the first distance (for example, 1
0 cm) is set in advance, and while the tunnel boring machine 1 is excavating the first distance, the estimated value of the rock mass characteristic of the face during the excavation is the first threshold value A.
If it continues to fall below, it is predicted that a fragile layer may exist ahead of the face by a predetermined distance, and while the tunnel boring machine 1 is excavating the second distance, the estimated face face during excavation It is characterized in that if the value indicating the natural property is continuously lower than the second threshold value B, the face may be close to the fragile layer.

According to the second aspect of the invention, the threshold value comprises a first threshold value and a second threshold value, and the first threshold value and the second threshold value are combined. By comparison, in addition to the presence of a fragile layer in front of the face, whether the fragile layer is a predetermined distance in front of the face or whether the fragile layer is in a position close to the face, It is possible to roughly understand the location of the. In addition, even if the nature of the ground changes suddenly, the second distance is shorter than the first distance, and the ground at the face during excavation estimated from the second threshold and the excavation data. It is possible to quickly predict the possibility that the face is close to the fragile layer by comparison with the value indicating the property. For this reason, the tunnel boring machine cannot predict a sudden change in the ground, and it is possible to avoid a situation where the vulnerable layer is encountered and excavation becomes impossible.

A rock excavating method according to a third aspect of the present invention is, for example, as shown in FIG. 1, FIG. 2 and FIG. 4, using the face forward rock mass property predicting method according to the first or second aspect of the present invention. It is characterized in that the tunnel boring machine 1 is used to excavate the ground while predicting the nature of the ground ahead, and when it is predicted that a fragile layer is present in front of the face, the tunnel boring machine is stopped.

According to the third aspect of the present invention, by comparing the preset threshold value with the value indicating the rock mass property of the face during excavation, which is estimated from the excavation data, the rock mass property in front of the cutting face is compared. It is supposed to stop when it is predicted that there is a possibility that a fragile layer exists in front of the face. Therefore, it is possible to objectively judge whether or not the excavation of the tunnel boring machine should be stopped.
Therefore, the judgment of whether or not to stop the excavation of the tunnel boring machine does not depend on the experience of the person who makes the judgment. Further, if the tunnel boring machine is stopped, it is possible to directly visually observe the nature of the ground of the cutting face from the inside of the chamber through a gap such as a scraper provided in the cutter head of the tunnel boring machine. Therefore, after visually observing, it is possible to judge whether or not to carry out the front reception, or to perform the geological exploration in front of the face in more detail by forming a plurality of boring holes.

The invention according to claim 4 is the ground excavating method according to claim 3, wherein, for example, as shown in FIG. 2 or 4, when it is predicted that a fragile layer is present in front of the face, It is characterized in that a plurality of boring holes are drilled in the ground in front of the cutting face to perform geological exploration in front of the cutting face.

According to the fourth aspect of the present invention, the value in front of the cutting face is compared by comparing the value indicating the natural ground property of the face during the excavation estimated from the excavation data of the tunnel boring machine with a preset threshold value. If it is predicted that there is a fragile layer in the area, a boring hole will be drilled in multiple locations toward the front of the face to perform geological exploration in front of the face. Can be understood in more detail.

According to the invention of claim 5, in the method of excavating rock according to claim 4, for example, as shown in FIG. 2 or 4, prior to excavation of rock according to the result of the geological exploration in front of the face. It is characterized by performing a front reception to reinforce the ground in front of the face.

According to the fifth aspect of the present invention, a plurality of boring holes are formed in front of the cutting face to perform geological exploration in front of the cutting face, and according to the result, the ground in front of the cutting face is preceded by excavation of the natural ground. It is supposed to take the advance reception to reinforce the mountain. Therefore, it is possible to continue the excavation of the ground without improving the ground in front of the face to prevent the ground from collapsing and preventing the tunnel boring machine from being caught by the fragile layer and making it impossible to proceed with the excavation.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a face forward rock mass property predicting method and a rock excavating method according to the present invention will be described in detail below with reference to the drawings.

First, the structure of a tunnel boring machine 1 (hereinafter referred to as TBM1) used when excavating the natural ground will be described with reference to FIG. The TBM 1 includes a plurality of disc cutters 11a, a rotatably provided cutter head 11, a thrust jack 12 connected to the center of rotation of the cutter head 11 and extendable and retractable, and the thrust jack 12 is extended to advance. A gripper 13 and the like are provided for taking a reaction force when the gripping is performed.

To excavate the ground with TBM1, the following procedure is followed. First, the TBM 1 is installed at a position to be excavated, and the gripper 13 is pressed against the wall surface of the natural ground to take a reaction force. Then, the thrust jack 12 is extended while rotating the cutter head 11 and the disk cutter 11a, respectively.
Promote the BM1 body. And the thrust jack 12
Is extended from the contracted state to the extendable range, one excavation (hereinafter, the stroke is indicated as st) is completed.

When the first excavation is completed, the pressing of the gripper 13 against the natural ground is released, and the thrust jack 12 is contracted. Then, the gripper 13 is newly pressed against the wall surface of the ground, and the cutter head 11 and the disk cutter 11a are
The thrust jack 12 is extended while excavating by rotating each of the. By repeating this, it is possible to excavate the natural ground and construct an underground structure such as a tunnel having a total length of 3,000 m.

Next, the method for evaluating the nature of the face in front of the ground and the method for excavating the ground according to the present embodiment will be described with reference to FIG. The method for evaluating the nature of a face in front of a face according to the present embodiment is such that when the TBM1 is advanced to construct a tunnel, the cutter torque, thrust thrust, cutter rotation speed, cutter penetration amount, and excavation required when the TBM1 excavates the natural ground. Velocity is collected as excavation data, and the rock mass strength of the face during excavation (a value that indicates the nature of the ground) is estimated from the collected excavation data, and the estimated rock mass strength of the face during excavation and preset By comparing with the threshold value, the rock mass properties of the unexcavated section in front of the face are predicted. Further, the rock excavation method is to advance the rock excavation while predicting the rock mass property in front of the cutting face by using the above-mentioned rock face front rock mass property prediction method.

First, the setting of the threshold value will be described.
The threshold value is set in advance before starting the excavation of TBM1. Two thresholds, a first threshold A and a second threshold B, are set. The first threshold value A is a value of rock mass strength that suggests the possibility that a fragile layer exists ahead of the face by a predetermined distance, and is 18 MPa in the present embodiment.
Is set. The second threshold value B is a rock mass strength value that suggests that the face may be close to the fragile layer, and is set to 10 MPa in the present embodiment. The values of 18 MPa and 10 MPa can be set as appropriate by analyzing past excavation cases.

Here, "the value of the rock mass strength indicating the possibility that a fragile layer exists ahead of the cutting face by a predetermined distance" means that the rock mass strength of the cutting face at present is sufficient to take the reaction force necessary for excavation of TBM1. However, it is possible to visually confirm that the ground is hard and the geology is relatively stable.
If the bedrock strength of the face is continuously lower than the first threshold value A while BM1 is excavating about 1st (first distance), the bedrock strength gradually decreases in front of the face,
It is a value indicating that TBM1 may encounter a fragile layer in some time. In addition, in the present embodiment, the “predetermined distance ahead of the face” means 8 to 10 m ahead of the face.

Further, "the value of the rock mass strength suggesting the possibility that the cutting face is close to the fragile layer" means that the rock mass strength of the cutting face at present is a value sufficient to take the reaction force necessary for excavation of TBM1. However, if the point where the rock face strength of the face is below this second threshold value B continues for 10 cm (second distance) or more, for example, as a value that suggests that the ground becomes extremely weak in the vicinity of the face. It is set. Further, "the face is close to the fragile layer" means that the fragile layer exists 1 to 3 m ahead of the face.
Or it means that part of the face encounters the fragile layer.

Further, before starting the excavation of the TBM 1 in order to construct a tunnel, it is desirable to carry out a geological survey of the ground to be excavated in advance. The possibility of existence of a fragile layer based on prior geological surveys, whether the shape of the fragile layer is likely to be planar or uneven when exposed, etc. It is good to know. Further, in constructing the tunnel, it is preferable that at every time the TBM 1 digs a predetermined distance of, for example, about 50 m, at least one boring hole is formed toward the front of the face to perform geological exploration in front of the face. As described above, by performing the drilling search every time the TBM 1 advances a predetermined distance, it is possible to help predict the nature of the front face of the cutting face, which will be described below.

Further, from the excavation data, in order to estimate the rock mass strength of the face for which this excavation data was collected, it can be obtained according to the following equation (1). In the following, the rock mass strength of the cutting face estimated from the excavation data is called the estimated rock mass strength σc, and the one obtained from the thrust thrust and the cutter penetration amount is expressed as the estimated rock mass strength σc (F _N ). The value obtained from the quantity is expressed as the estimated rock mass strength σc (T _R ).

[Equation 1] Here, .sigma.c: estimating rock strength (MPa), F _N: Thrust thrust (kN), T _R: cutter torque (kN · m),
P: Cutter penetration amount (mm / rev), C ₁ , C ₂ : constant). The cutter penetration amount can be obtained by dividing the excavation speed of the TBM 1 by the rotation speed of the cutter head.

Actually, the following procedure is used for predicting the rock mass properties in front of the cutting face using the method for predicting rock mass front rock mass properties according to the present embodiment and for excavating the rock mass while predicting the rock mass properties. Follow

First, excavation of the TBM 1 is started in order to construct a tunnel (step S1). At this time, every time the TBM1 digs about 2 cm, the TBM1
Collects the excavation data required for excavating the natural ground, and obtains the estimated rock mass strength σc (F _N ) and the estimated rock mass strength σc (T _R ) from the collected drilling data. That is, TBM
Estimated rock mass strength σc (F _N ) every time 1 travels about 2 cm
And the estimated rock mass strength σc (T _R ) is calculated.

Here, the estimated rock mass strength σc from the excavation data
When obtaining (F _N ) and the estimated rock mass strength σc (T _R ), it is advisable to perform the processing using a personal computer or the like equipped with a control unit, a calculation unit, a display unit and the like. Further, when the estimated rock mass strength σc (F _N ) and the estimated rock mass strength σc (T _R ) are obtained from the excavation data by using the personal computer as described above, the processing result is shown on the display unit, for example, as shown in FIG. As described above, the transition of the estimated rock mass strength σc in the already excavated section may be graphically displayed by using the x-axis as the excavation distance and the y-axis as the estimated rock mass strength σc (F _N ) and the estimated rock mass strength σc (T _R ). Further, at this time, as shown in FIG. 2, the estimated estimated rock mass strength σc
It is preferable to display the first threshold value A and the second threshold value B together with the transitions of (F _N ) and the estimated rock mass strength σc (T _R ).

Next, in step S2, the estimated rock mass strength σc (F _N ) or the estimated rock mass strength σc obtained every 2 cm is obtained.
It is determined whether or not the value of (T _R ) is continuously lower than the second threshold value B (10 MPa) while the TBM 1 is excavating the section of 10 cm. Here, the estimated rock mass strength σc (F _N ) or the estimated rock mass strength σc (T _R ) obtained every 2 cm
If it is determined that the value of is continuously lower than the second threshold value B in the section of 10 cm (S2: Y), it is determined that the face may be close to the fragile layer. Go to step S4. Here, if it is determined to be no (S2: N), it is determined that the face may not be close to the fragile layer, and the process proceeds to step S3.

Next, in step S3, the estimated rock mass strength σc (F _N ) or the estimated rock mass strength σc obtained every 2 cm.
It is determined whether or not the value of (T _R ) is continuously lower than the first threshold value A while the TBM 1 advances for the first step. Here, when it is determined that the value of the estimated rock mass strength σc (F _N ) or the estimated rock mass strength σc (T _R ) is continuously lower than the first threshold value A while the TBM1 is digging 1st ( In S3: Y), it is highly possible that the fragile layer exists in front of the face, and the process proceeds to step S4. If it is determined to be no (S3: N) here, it is determined that the fragile layer is not likely to exist in front of the face, and the process returns to step S1.
Continue to excavate TBM1.

Next, as described above, when it is predicted in step S2 that the face may be close to the fragile layer, or in step S3, the fragile layer may be present a predetermined distance ahead of the face. If it is predicted that there is, the process proceeds to step S4. Then, in step S4, the excavation of the TBM 1 is stopped.

Then, in step S5, the natural characteristics of the cutting face are directly observed by illuminating with light or the like from the gap of the scraper 11b provided on the cutter head 11 in the chamber. At this time, visually check whether the ground has large cavities, whether the ground has collapsed, and whether there is spring water. Then, when it is visually determined that the ground is relatively hard and stable (S5: Y), it is determined that the nature of the ground in the face is good, and the process proceeds to step S6. Here, when it is determined to be no (S
5: Y), the process proceeds to step S10.

In step S6, if the fragile layer is exposed by the geological survey carried out in advance, it is judged whether or not the shape is planar. Then, when the fragile layer is exposed by the geological survey in advance, and when it is determined that the shape is planar (S6: Y), the process proceeds to step S7. If it is determined that the answer is NO (S6: N), the step S
Go to 8.

In step S7, it is determined whether or not the fragile layer is assumed to exist in the drilling exploration carried out by drilling about one boring hole every time the TBM 1 drills 50 m. Here, when it is determined that the fragile layer is present in this drilling exploration (S7:
For Y), the process proceeds to step S10. Here, if it is determined to be no (S7: N), the process proceeds to step S8.

Next, in step S8, a plurality of boring holes of about 20 m are bored in the ground in front of the cutting face to perform geological exploration in front of the cutting face. At this time, it is preferable to form at least one boring hole from both sides of the TBM 1 and the top end portion toward the front of the face.

Regarding the geological exploration, for example, the geology of the drilling section can be explored by correlating the amount of drilling energy required when boring a boring hole with the nature of the ground. In addition, as another method, when drilling using a hydraulic rock drill having a damping function that receives and absorbs the impact reaction force from the ground against the impact on the ground, various types of hydraulic rock drills are operated. The hydraulic pressure (damping pressure) data of the hydraulic cylinder device and the hydraulic cylinder device that receives and absorbs the impact reaction force is collected through a hydraulic sensor, and the damping pressure data and the nature of the ground are associated to determine the geology of the drilling section. It may be explored. Furthermore, it is also possible to install multiple resistivity measuring electrodes on the face of the face and each of the boreholes, and to predict the natural properties in front of the face based on the resistivity values obtained from these electrodes. The geological exploration method is not particularly limited.

Then, in step S8, when the front face exploration is completed, the process proceeds to step S9, and it is determined whether or not the presence of a fragile layer in front of the front face is confirmed by the front face exploration. Then, in step S9, when the presence of the fragile layer is confirmed in front of the face (S9: Y),
Go to step S10. In step S9, when the presence of the fragile layer is not confirmed in front of the face (S9: N),
Returning to step S1, the excavation of TBM1 is continued.

In step S10, according to the result of the geological exploration in front of the cutting face in step S8, prior to the excavation of the natural ground by the TBM 1, a preliminary reception for reinforcing the ground in front of the cutting face is performed.

The fore-end can be, for example, fore-polling. Fore-polling is performed at a predetermined interval of about 10 along the outer circumference of the tunnel on the face of the face.
This is a construction method in which a hole is drilled at an elevation angle of 30 degrees to 30 degrees and a reinforcing member is inserted into the hole to obtain a reinforcing effect. Specifically, after drilling, mortar is filled and a steel bar (reinforcing member) with a diameter of about 25 mm is inserted, and the mortar type fore poling, which waits for the hardening of the mortar to obtain the reinforcing effect of the ground, and the steel pipe after drilling. A two-liquid urethane is injected at a high pressure by setting up an injection pipe made of urethane to cure the urethane, and the urethane fore poling that obtains the reinforcing effect of the ground by using this urethane as a reinforcing member and a steel pipe of about 10 m to 15 m (AGF There is an AGF (All Ground Fasten) method using a steel pipe) and an injection material.

Then, in step S10, the process returns to step S1 again and the excavation by the TBM 1 is continued until the pre-reception of the section requiring the pre-reception is completed.

Next, referring to FIG. 3, the above-mentioned rock mass property predicting method and the rock mass excavating method for excavating the rock mass while predicting the rock mass property in front of the face using this rock mass property predicting method. Will be described in more detail.

In FIG. 3, TBM1 is the position indicated by the arrow a.
It is assumed that 2095 m has already been dug at the location.
Then, the steps S1, S2 and
Repeat step S3 until T reaches the section indicated by arrow b.
Continue digging BM1. In the section indicated by arrow b,
Constant bedrock strength σc (F_N) Value is several times the first threshold A
It's still below, but it's a continuation while TBM1 digs 1st
Continuously estimated rock mass strength σc (F_N) Is the first threshold
Since it is not lower than A, by step S3
If it is judged to be no, it returns to step S1 again, and excavates the TBM1.
You can continue. Then, at the points indicated by arrows c and d
Similarly, the estimated rock mass strength σc (F _N) Or estimated rock
Board strength σc (T_R) Is less than the first threshold A
However, while TBM1 is digging 1st,
Constant bedrock strength σc (F_N) Or estimated rock mass strength σc (T_R)of
The value is not less than the first threshold A
Therefore, it is determined to be no in step S3 and the step is repeated.
Returning to S1, the excavation of TBM1 is continued.

Then, up to the point where TBM1 is indicated by arrow e
When excavated, the estimated rock mass strength σc (F _N) And estimated bedrock
Strength σc (T_R) Is less than the first threshold A
It Then, from the point indicated by arrow e to the point indicated by arrow f.
Section of about 1.5m, that is, TBM1 digs 1st
During this time, the estimated rock mass strength σ continuously exceeds the first threshold A.
c (T_R) Is less than the value. Therefore, above
The estimated rock mass strength σc (F_N) Or
Constant bedrock strength σc (T_R) Value TBM1 advances 1st
It is determined that the first threshold value A is continuously maintained while
It is predicted that there is a fragile layer in front of the face.
Then, at the point indicated by the arrow f, the excavation of TBM1
It is stopped (step S4).

Next, the nature of the ground of the cutting face is visually observed from the inside of the chamber at the point indicated by arrow f. At this time, it is confirmed that the ground is mainly composed of granite porphyry and is relatively hard and stable in appearance (S5: Y).

Then, when the natural characteristics of the face are directly visually confirmed, the process proceeds to step S6. In the present embodiment, it is understood from the previous geological survey that the fragile layer is likely to appear in an irregular shape (S6: N), and thus the process proceeds to step S8.

In step S8, three boring holes of about 20 m are bored in the ground in front of the cutting face to perform geological exploration in front of the cutting face. At this time, at least one boring hole is formed from both sides and the top end of the TBM 1 toward the front of the face.

Then, the process proceeds to step S9 and step S8.
According to the results of geological exploration, the ground weakened significantly from about 5 m ahead of the point indicated by arrow f, and as shown by the dotted line,
About 8m ahead from the point indicated by arrow f (point indicated by arrow g)
It was determined that the TBM1 could not be excavated at
The size of the vulnerable layer is also understood.

From the result of the above step S8, the bearing is carried out at the point indicated by the arrow f, and the ground before the face is reinforced prior to the excavation of the ground. When the preemption is completed, the process returns to step S1 to continue the excavation of TBM1. In addition,
In FIG. 3, the transition of the estimated rock mass strength is shown by the dotted line in front of the point indicated by the arrow f, but this does not carry out pre-receiving at the point indicated by the arrow f, and the TBM1 may have a fragile layer. If the digging is continued without predicting the sex, the value will change as such. In the present embodiment, as described above, the TBM1 predicts the existence of the fragile layer about 8 m before the fragile layer exists by the face front rock mass prediction method and carries out the pre-emption, as shown in FIG. Estimated rock mass strength σc (F _N ) or estimated rock mass strength σc
The value is close to 0 MPa as shown by the arrow g of (T _R ), and the TBM1 does not encounter the fragile layer and cannot excavate the TBM1.

According to the present embodiment, the TBM1 is advanced to construct a tunnel, and the TBM1 is operated in association with the advance of the TBM1.
The estimated rock mass strength σc (F _N ) and the estimated rock mass strength σc (T _R ) are obtained by collecting excavation data every time the BM1 advances by 2 cm. Whether or not the value of the estimated rock mass strength σc (F _N ) or the estimated rock mass strength σc (T _R ) continuously falls below the second threshold value B while the TBM1 is excavating a section of 10 cm (step S2). , Or whether the face may be close to the fragile layer and whether the face is predetermined depending on whether or not the TBM1 continuously falls below the first threshold value A during the excavation of the 1st section (step S3). It is judged whether there is a possibility that a fragile layer exists ahead of the distance. Since the excavation data is obtained from the entire face where the face reaches a diameter of 4,5 m, compared with the conventional case where the rock mass in front of the face is evaluated from a borehole with a diameter of about 65 mm, It is possible to evaluate the rock mass properties in front of the cutting face from the surface data obtained by averaging the properties. Therefore, even if the fragile layer exists in front of the face in a non-uniform shape, the existence of the fragile layer can be accurately grasped from the surface data, and the boring hole can be drilled as in the past. Since the position where it did not catch the vulnerable layer, the tunnel boring machine does not notice the existence of the vulnerable layer, and does not fall into the situation where the vulnerable layer is encountered and excavation is impossible.

Further, since the presence or absence of the fragile layer in front of the face is judged while continuing the excavation of TBM1, TBM
With the excavation of No. 1, it is possible to quickly detect the presence or absence of the fragile layer in front of the face.

The threshold values are the first threshold value A and the second threshold value.
Even if it is predicted that the face may be close to the fragile layer due to the second threshold value B in step S2, the first threshold value is determined in step S3. Even when it is determined that the fragile layer may exist in front of the face by a predetermined distance based on the value A, the process proceeds to step S4 and T
The excavation of BM1 is stopped. That is, even when the nature of the ground changes rapidly and the fragile layer exists in the immediate vicinity of the face, the property of the ground changes gradually and the fragile layer exists a predetermined distance ahead of the face. Also, estimated rock mass strength σc
(F _N ) and the estimated rock mass strength σc (T _R ) are compared with these threshold values A and B to quickly detect the existence of the fragile layer and stop the TBM1. Therefore, TBM
It is possible to avoid the situation where 1 is caught in the fragile layer and cannot be excavated. Further, the judgment for stopping the excavation of the TBM 1 can be made objectively and is not affected by the experience of the person making the judgment.

Further, since the excavation of the TBM 1 is stopped, it is possible to directly confirm the nature of the ground at the face in step S5. If the nature of the ground at the face is not good, the process immediately proceeds to step S10. The receiving method can be implemented.

Further, in step S8, the boring hole is formed at a plurality of points toward the front of the face to perform geological exploration in front of the face, and therefore the estimated rock mass strength σc
(F _N ) and estimated rock mass strength σc (T _R ) and threshold A,
The presence or absence of the fragile layer in front of the cutting face can be confirmed by comparison with B, and the position, scale, etc. of the fragile layer can be grasped in more detail by the geological survey in front of the cutting face at a plurality of locations.

If it is determined Yes in any of step S5, step S7, and step S9, the process proceeds to step S10, in which the front support for reinforcing the ground in front of the face is excavated before the ground is excavated. Is supposed to do.
Therefore, it is possible to continue excavation of the natural ground without improving the natural ground in front of the face to prevent the natural ground from collapsing and preventing the TBM 1 from being caught by the fragile layer and making it impossible to proceed with the excavation.

The present invention is not limited to the above-mentioned embodiments, and it goes without saying that the present invention can be appropriately modified without departing from the gist of the present invention. For example, in the above-described embodiment, it is determined in step S6 whether or not the shape of the fragile layer is planar, and in step S7 it is determined whether or not the existence of the fragile layer is assumed in the continuous application drilling survey. It is supposed to do. However, these steps S6 and S7 do not necessarily have to be performed. For example, as shown in FIG.
The process may directly proceed from step S5 to step S8.

Although two threshold values, the first threshold value A and the second threshold value B, are set, the present invention is not limited to this. For example, the first threshold A
Only the second threshold B may be set.
Only one may be set. However, as in the present embodiment, the first threshold value A is set as the value of the rock mass strength indicating the possibility that the fragile layer exists ahead of the face by a predetermined distance, and the face is close to the fragile layer. By setting the second threshold value B as the value of the rock mass strength that indicates the possibility that rocks are present The existence of a vulnerable layer can be quickly detected.

The first threshold value A is 18MP.
a, the second threshold B was set to 10 MPa,
This numerical value is not particularly limited, and may be changed as appropriate according to the nature of the ground to be excavated.

Similarly, in step S3, it is determined whether the estimated rock mass strength of the cutting face continues to fall below the first threshold value A for the 1st section or whether the estimated rock mass strength of the cutting face is 10 cm in the step S2. Although it has been decided to continuously determine whether or not it falls below the second threshold value B, the distances of 1st and 10 cm are not particularly limited, and the first threshold value A and the second threshold value The value set as the threshold value B may be appropriately changed depending on the nature of the natural ground.

The estimated rock mass strength is calculated from the excavation data according to the equation (1), and the first threshold value and the second threshold value are set as the rock mass strength values. It is not something that will be done. If the rock mass properties can be evaluated from the drilling data by correlating the drilling data with the rock mass properties, it is not necessary to set the rock mass strength. For example, the value of the cutter torque required for excavating the natural ground and the threshold value corresponding to the value of the cutter torque may be set to determine the natural property in front of the cutting face. The point is to estimate the rock mass properties of the face during excavation from the drilling data, set a threshold value that can be compared with the estimated rock mass properties, and estimate the rock mass properties estimated from the threshold value and the drilling data. If it is possible to judge the rock mass characteristics in front of the face by comparing the values indicating

[0061]

According to the invention as set forth in claim 1, excavation data of a face during excavation of a tunnel boring machine is collected, and a value indicating a rock mass characteristic of the face under excavation is estimated from the excavation data and estimated. If the excavation data continues to fall below the threshold value while the tunnel boring machine is excavating a predetermined distance, the fragile layer exists in front of the face face. I predict that there is a possibility. Since the collected excavation data for the face during excavation is collected from the entire face where the face reaches a diameter of 4,5 m, the diameter of 6
Compared with the case of evaluating the rock mass properties in front of the cutting face from a borehole of about 5 mm, the rock mass properties in front of the cutting face are evaluated based on surface data obtained by averaging the properties of the rock mass. Therefore, even if the fragile layer exists in a non-uniform shape in front of the face, the existence of the fragile layer can be accurately grasped from the surface data.

Since the excavation data is collected as the tunnel boring machine advances and the threshold value is compared with the estimated value indicating the rock mass characteristics of the face, it is possible that a weak layer in front of the face exists. Whether or not there is can be predicted as the tunnel boring machine is dug. In addition, when the characteristics of the ground are stable, there is no need to stop the excavation and drill a boring hole in order to predict the nature of the ground in front of the cutting face. The construction can be maintained.

According to the second aspect of the invention, the same effect as that of the first aspect can be obtained, and the threshold value has the first threshold value and the second threshold value. Therefore, in the case that the nature of the ground gradually changes, it is predicted by comparing the first threshold value with the value indicating the nature of the ground in the face during excavation, which is estimated from the excavation data. For a location that changes abruptly, it can be predicted by comparing the second threshold value with a value indicating the rock mass characteristics of the face under excavation estimated from the excavation data. Further, by presetting the first threshold value and the second threshold value, it is possible to predict whether the fragile layer is a predetermined distance ahead of the face, or whether the face is close to the fragile layer. You can Then, since the position where the vulnerable layer exists can be roughly understood, it is possible to avoid the situation where the tunnel boring machine encounters the vulnerable layer and is unable to dig depending on the position where the vulnerable layer is considered to exist. can do.

According to the invention described in claim 3, not only the same effect as in claim 1 or 2 can be obtained, but also from the preset threshold value and the excavation data collected in the face during excavation. By comparing with the estimated value indicating the rock mass properties of the face, the rock mass properties in front of the face are predicted. If it is predicted that a fragile layer may exist in front of the face, the tunnel boring machine will be stopped. Therefore, it is possible to objectively judge whether or not the excavation of the tunnel boring machine should be stopped. Further, if the tunnel boring machine is stopped, it is possible to directly visually observe the nature of the ground of the cutting face from the inside of the chamber through a gap such as a scraper provided in the cutter head of the tunnel boring machine. Therefore, after visually observing, it is possible to judge whether or not to carry out the front reception, or to perform the geological exploration in front of the face in more detail by forming a plurality of boring holes.

According to the invention described in claim 4, not only the same effect as in claim 3 is obtained, but when it is predicted that a fragile layer may exist in front of the face, It is supposed that the boring hole will be drilled in multiple places toward the front of the face to perform geological exploration in front of the face. Therefore, the existence of a fragile layer in front of the cutting face should be checked by comparing the excavation data with the threshold value, and the location and scale of the fragile layer should be grasped in more detail by the geological survey in front of the cutting face at multiple locations. You can

According to the invention of claim 5, not only the same effect as in claim 4 can be obtained, but a plurality of boring holes are bored in front of the face to perform geological exploration in front of the face.
According to the result, prior to the excavation of the natural ground, a preliminary reception is performed to reinforce the natural ground in front of the face. Therefore, it is possible to continue the excavation of the ground without improving the ground in front of the face to prevent the ground from collapsing and preventing the tunnel boring machine from being caught by the fragile layer and making it impossible to proceed with the excavation.

[Brief description of drawings]

FIG. 1 is a side view of a tunnel boring machine used in a method for predicting rock face forward rock mass properties and a rock excavation method for a tunnel boring machine according to an example of the present invention.

FIG. 2 is a flow chart showing a procedure of a method for predicting the nature of a natural rock face in front of a face and a method for excavating a rock in an example of the present invention.

[Fig. 3] In the method of predicting rock mass forward rock mass properties and rock mass excavation method according to an example of the present invention, excavation data and rock mass properties are correlated to evaluate changes in drilling data during drilling to evaluate rock mass properties at the rock face. It is shown as a transition of the value.

FIG. 4 is a flow chart showing a procedure of a method for predicting the nature of a rock front rock mass and a rock excavation method according to another example of the present invention.

[Explanation of symbols]

1 Tunnel boring machine (TBM) A first threshold B second threshold

Continued front page    (72) Inventor Koji Ishiyama             Nishimatsuken 1-20-10 Toranomon, Minato-ku, Tokyo             Inside the corporation F-term (reference) 2D054 AC01 BA03 FA01 GA10 GA15                       GA42 GA63 GA64 GA65 GA72

Claims (5)

[Claims] 1. A method for predicting rock mass in front of a cutting face when excavating a rock mass with a tunnel boring machine, wherein a fragile layer may exist in the rock mass in front of the cutting face. The threshold value is set in advance as a value indicating the rock mass property suggesting that the tunnel boring machine is excavated, and the cutter torque and thrust thrust required to excavate the rock ground at the face of the tunnel boring machine , At least one of the cutter rotation speed and the cutter penetration amount is collected as excavation data, and the value indicating the rock mass characteristic of the face under excavation is estimated from the collected excavation data, and the estimated face during excavation During the estimated excavation while the tunnel boring machine is excavating a predetermined distance set in advance, by comparing the value indicating the rock mass property with the threshold value. When the value indicating the rock mass property of the cutting face continues to fall below the threshold value, it is predicted that a fragile layer may exist in front of the cutting face. 2. The method for predicting rock mass forward rock mass property according to claim 1, wherein the threshold value is a value indicating rock mass property which suggests that a fragile layer may exist in a predetermined distance ahead of the rock face. One threshold value and a value indicating a rock mass property that suggests that a fragile layer may exist at a position closer to the face than the predetermined distance from the face indicated by the first threshold to the fragile layer. With a second threshold, which is, if the value indicating the rock mass characteristics in the estimated face during excavation is continuously lower than the threshold, a fragile layer may exist in front of the face. As the predetermined distance that the tunnel boring machine advances when it is predicted that there is a first distance corresponding to the first threshold and the first distance corresponding to the second threshold. A second distance shorter than the preset distance While the machine travels the first distance, if the value indicating the rock mass characteristics of the estimated face during excavation continues to fall below the first threshold value, the fragile layer is present at a predetermined distance ahead of the face. Predicting that there is a possibility of existing, while the tunnel boring machine is excavating the second distance, the estimated value indicating the rock mass property at the face during excavation continues the second threshold value. If it falls below this, it is predicted that the face may be close to the fragile layer. 3. A ground boring machine is excavated by a tunnel boring machine while predicting the rock mass property in front of the cutting face using the method for predicting rock mass in front of the cutting face according to claim 1 or 2. A method of excavating a rock, comprising stopping the excavation of a tunnel boring machine when it is predicted that a fragile layer exists. 4. The ground excavating method according to claim 3, wherein when it is predicted that a fragile layer may exist in front of the face, a plurality of boring holes are formed in the ground in front of the face. A geological excavation method characterized by performing a geological survey in front of the face. 5. The ground excavation method according to claim 4, wherein prior to excavation of the natural rock, pre-bearing for reinforcing the natural rock in front of the natural cutting face is performed according to the result of the geological survey in front of the cutting face. How to excavate the ground.