JP2000146631A - Method for evaluating tunnel working face breakdown probability - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for evaluating tunnel working face breakdown probability whose instantaneity and readiness are excellent at the job site by allowing even an inexperienced operator to easily and objectively judge and evaluate the breakdown probability of a wall face. SOLUTION: Whether or not each of plural judgment blocks 21 surrounded by cracks 20 on a wall face 10 is an infinite rock lump block continuing to a natural ground or a discontinuous finite rock lump block is estimated based on plural crack patterns 30 artificially planned for a strike θ, inclination, and crack interval S, and the breakdown probability of the wall face is calculated according to the rate of the finite rock lump block to the whole judgment blocks.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for evaluating the probability of collapse of a tunnel face, and more particularly, to artificially devising a crack actually occurring on a face instead of observing it for analysis data. The present invention relates to a tunnel face collapse probability evaluation method for performing analysis based on a crack pattern.

[0002]

2. Description of the Related Art A method of estimating and evaluating the probability and tendency of a collapsed wall, such as an excavated wall such as a tunnel face, or a collapsed slope in a landslide area, has conventionally required a staff member at the site. In addition to methods such as observing the wall surface and checking the width and frequency of cracks, or the geological conditions, and predicting the probability of collapse based on personal experience and subjectivity, strain gauges and pressure There has been a method of directly attaching a sensor or the like and feeding back data obtained from such sensors to an analysis system to estimate a collapse probability (for example, JP-A-9-264767 or JP-A-9-264766). .

[0003] In addition, the target wall surface is photographed by various image pickup means such as a CCD camera, and cracks and floods generated on the surface or the strike of the stratum are extracted and clarified by image processing, and further obtained. A method of estimating the probability of collapse by performing analysis based on the observed data (for example, Japanese Patent Application Laid-Open No. Hei 7-37096,
No. 3145).

[0004]

However, in any of the above-mentioned conventional methods for evaluating the probability of collapse, the staff at the site judge by experience based on the observation result obtained at the site, or discard the data obtained at the site. The data is selected and used, and data analysis is performed according to the analysis conditions determined by the engineer or the researcher. It is undeniable that the collapse probability is ultimately influenced by the subjective judgment of the engineer or the researcher.

[0005] In addition, a person in charge of making a decision or a technician who performs an analysis must be a so-called skilled person who has abundant work experience in each workplace. Because of the lack of experience and so-called engineering judgment, which is unstable and indefinite, it is very difficult for an inexperienced person to engage in the same work and make an accurate judgment.

The number of skilled technicians at construction sites and the like described above is decreasing year by year, and the number of daily tasks that each technician must perform is increasing year by year from the viewpoint of environmental issues and the public nature of work, and the number of workers is diversified and large. For this reason, rare skilled technicians are forced to perform complicated tasks.

Therefore, it is becoming difficult for a skilled technician to check the wall surface on site every day and quickly determine the probability of collapse. On the other hand, in order to compensate for this, it is necessary to install various sensors, imaging means, and the like for observation. Even if data is obtained and a technician analyzes the data and estimates the probability of collapse, the method is not instantaneous at the site, and it takes a long time to evaluate and take actual response measures. It takes time.

Moreover, the method using the above-mentioned various sensors and image pickup means is not of a nature that can be applied to any site because the installation thereof requires a large cost.

Therefore, the present invention has been made in view of such conventional problems, and it is possible to easily and objectively judge the probability of collapse of a wall and to make an evaluation even if a person is not an expert. Another object of the present invention is to provide a tunnel face collapse probability evaluation method which is excellent in the on-site immediateness and responsiveness.

[0010]

SUMMARY OF THE INVENTION The present invention has been made to achieve the above object, and is a collapse probability evaluation method for calculating a collapse probability of a wall of a tunnel based on a crack in the wall of the tunnel. Based on multiple crack patterns artificially devised for strike, dip, and crack interval, each of a plurality of judgment sections formed by being surrounded by cracks on the wall is an infinite rock mass section connected to the hinterland mountain Or a discontinuous finite block section is estimated, and the ratio of the finite block section to the total determination section is defined as the collapse probability of the wall surface.

[0011]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is an explanatory diagram showing a concept of setting a crack pattern in the tunnel face collapse probability evaluation method of the present invention.

In implementing the tunnel face collapse probability evaluation method of the present invention, as shown in the figure, the assumed shape of the tunnel face 10 is determined, and the running, inclination, and crack interval are appropriately set on such a face. Must be done.

First, a running direction indicating on which direction the crack 20 is formed on the face 10 is set.
(A) shows a strike pattern in which a crack 20 extends, for example, on the upper right side of the face 10, the inclination of the crack is represented by a strike θ, and the interval between the cracks 20 is represented by a crack interval S. (A) As shown in the drawing, in addition to the case where the strike of the crack 20 on the face 10 is only one set, (b) in FIG. Indicates a more advanced situation. The inclination at that time is the strike θ1 for one of the cracks 20 and θ2 for the other, and the crack intervals are S1 and S1, respectively.
It is distinguished as S2.

The inclination of a crack (not shown) extending from the target wall toward the hinterland instead of the inclination of the crack on the wall such as the strike θ is referred to as an inclination. It extends toward 60 degrees (that is, the inclination is 60 degrees).

The setting of the crack pattern 30 as described above is as follows.
For example, a pattern serving as a reference is appropriately determined for the inclination, and the strike direction θ and the crack interval S of the crack are finely changed for each reference inclination pattern (for example, several tens of patterns are changed using random number generated numbers). A number of crack patterns are systematically set.

However, if too many crack patterns are set, there is almost no difference between the crack patterns, and the user who uses the obtained collapse probability does not hesitate in selecting one. Is considered to be appropriate.

The crack pattern 30 is set as described above,
Subsequently, the collapse probability is estimated based on these crack patterns 30. The determination section 21 which is a closed area surrounded by the set cracks 20 is determined by the hinterland 40
And the finite rock mass 22 is discontinuous, for example, the geological condition shown in FIG.

The finite rock mass 22 is not collapsed at present due to the frictional resistance with the surrounding ground 40, but is slid and pushed out into the tunnel inner space 50 if the friction with the surroundings is weakened. This may lead to collapse of the wall as it is.

The finite rock mass 22 is called, for example, a “key block” in the sense of holding the key of the collapse, and as shown in FIG. 3, a large number of judgment sections 21 () formed by cracks 20 on the face 10. For example, by estimating the ratio of the key block 22 in 65 sections in the figure), the tunnel face collapse probability evaluation method of the present invention is executed.

As a method of estimating how many key blocks 22 occur, a key block is set by identifying a discontinuous surface in the rock three-dimensionally, and the structure and directionality of the rock joints are determined.
In addition, there is a method called a key block analysis method for estimating the mobility of a key block from mechanical characteristics and the like, and an analysis method called an individual element method.

For example, the tunnel face collapse probability evaluation method of the present invention is executed using a key block analysis method, and the obtained result is a collapse probability table 60 in FIG.

The collapse probability table 60 shows that the horizontal axis 61 indicates the crack 2
The strike θ of 0 is shown at appropriate intervals, and the vertical axis 62 shows the probability of collapse 63 under each condition, taking the crack interval S at every 0.5 m, for example.

When actually used, this collapse probability table 60
It is preferable that the sheet is sandwiched in a field note or the like, or is formed in a size that can be attached to the back cover, and a person or the like observing the target face face 10 preferably carries this.

A person observing the face 10 is
The running direction θ, the inclination, and the crack interval S of the crack 20 occurring at the time are measured easily and collated with the falling probability table 60 possessed to quickly and objectively know the falling probability 63 of the target face 10. It will be.

In this embodiment, the key block analysis method is used. However, the present invention is not limited to this, and any analysis method may be used as long as a similar result can be obtained.

[0027]

As described above in detail, according to the tunnel face collapse probability evaluation method of the present invention, a site clerk who makes a judgment on a collapse probability and a technician who conducts analysis have a considerable amount of work experience. It is not necessary to be a so-called skilled person, and even if the person is not a skilled person, it is possible to easily and objectively determine the probability of collapse and make an evaluation.

In addition, by using the collapse probability table based on the tunnel face collapse probability evaluation method of the present invention, it is possible to make an evaluation on the spot where the face is observed and to take an actual countermeasure, and to take immediate action on site. Gender and responsiveness are greatly improved.

[Brief description of the drawings]

FIGS. 1A and 1B are explanatory diagrams showing the concept of setting a crack pattern in a tunnel face collapse probability evaluation method of the present invention.

FIG. 2 is an explanatory diagram showing a state in which a judgment section is a finite block block that is discontinuous to a hinterland mountain in the tunnel face collapse probability evaluation method of the present invention.

FIG. 3 is an explanatory diagram showing a monitor screen when a run, an inclination, and a crack interval of a crack are set and an analysis is performed in the tunnel face collapse probability evaluation method of the present invention.

FIG. 4 is an explanatory diagram showing a collapse probability table in which the collapse probability obtained by the tunnel face collapse probability evaluation method of the present invention is shown with the horizontal axis representing crack running and the vertical axis representing crack spacing.

[Explanation of symbols]

 θ Strike S Crack spacing 20 Crack 21 Judgment section 22 Finite rock mass 30 Crack spacing 40 Hokuchiyama 63 Collapse probability

 ──────────────────────────────────────────────────続 き Continued on front page (72) Inventor Kenichiro Suzuki 4-640 Shimoseito, Kiyose-shi, Tokyo F-term in Obayashi Corporation Technical Research Institute Co., Ltd. 2F076 BA18 BB08

Claims (1)

[Claims] 1. A collapse probability evaluation method for calculating a collapse probability of a wall of a tunnel based on a crack of an inner wall of the tunnel, the method comprising: calculating a plurality of crack patterns artificially devised for a strike, a slope, and a crack interval. Based on the estimation, it is estimated whether each of the plurality of judgment sections formed by being surrounded by cracks on the wall is an infinite block block connected to the hinterland or a finite block block that is discontinuous. A method for evaluating the probability of collapse of a tunnel face, wherein the ratio of the finite block section occupying the determination section is defined as the collapse probability of the wall.