JPH09126970A - Method for testing fragility of natural ground - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the stability of the ground and the efficiency of drilling operation by each kind of drilling machine by obtaining a characteristic value for properly evaluating the fragility of natural ground. SOLUTION: In the fragility testing method, a rough granular rock sample of 0.5 kg whose particle diameter approximately ranges from 10 to 20mm obtained from a rock sample 10 which is sampled from the ground to be drilled using a sieve having a mesh dimension of 9.5 mm and 19.0 mm is packed into a mold 11, a stiffening stand 12 is installed on the rock sample 10, and a weight 13 with a weight of 14kg is vertically dropped for twenty times from a height of 25 cm via a support rod 14. The rock sample 10 within the mold 11 which is crushed due to the fall is passed through the sieve with a net dimension of 9.5 mm and a fragility value is obtained from the passage percentage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for testing the brittleness of rocks, and more particularly to a method for testing brittleness of rocks used to evaluate the degree of brittleness of rocks to be excavated by an excavating machine.

[0002]

2. Description of the Related Art The degree of brittleness of a rock indicates the brittleness of the rock, and especially for rocky ground ranging from soft rock to hard rock.
It is desirable to appropriately evaluate the stability of the ground and the efficiency of excavation by various excavating machines, depending on the degree.

On the other hand, a tunnel boring machine represented by a tunnel boring machine (hereinafter referred to as "TBM") is
Unlike conventional excavation methods, it is a machine that excavates while cutting or crushing the entire cross section of the tunnel by using a rotating cutter without using explosives, and in particular, it has a stable self-supporting face from soft rock to hard rock. It is a tunnel excavating machine effective for the ground. In addition, this excavation method using a tunnel machine excels in Japan compared to overseas because it is compatible with the complicated geological conditions unique to Japan, including strata with poor independence such as shatter zones and soft layers. However, due to improvements such as the application of the shield mechanism, it has become possible to promote geological compatibility and appeal for its high-speed workability. Has arrived.

According to the tunnel excavator such as the TBM, the excavation work of the tunnel is performed by pressing the roller cutter mounted on the rotating cutter head against the ground and crushing it. Working,
Since it is not possible to directly observe the condition of the face,
The conventional ground evaluation method cannot be applied as it is. In addition, as a construction management method for tunnel excavation by a tunnel excavator, a method that is commonly used in the past to evaluate the physical properties of the ground by measuring rock strength and elastic wave velocity predicts the workability of excavation work. The current situation is that we cannot do it enough.

On the other hand, the excavation efficiency of the tunnel machine is
Since it is greatly influenced by the nature of the ground such as the hardness and brittleness of the ground, in order to proceed with the excavation work reasonably and efficiently, the nature of the ground in front of the face must be cut with the cutting efficiency of the cutter head. It is becoming an important issue to establish an index that shows the excavation efficiency so that the excavation speed can be accurately predicted, in addition to understanding the relationship with

[0006] As a method for managing the excavation work using such an index showing the drilling efficiency, a drilling index (DRI: Drilling Rate Index) or a bit wear index (BWI: Bit Wear Index) is used overseas. Have been proposed and their applicability has already been verified. Here, the drilling index is the value of DRI calculated from the DRI calculation diagram based on the brittleness value obtained by the brittleness test and the J value of the sea bar obtained by the miniature drill test, and bit wear. The index is the value of BWI calculated from the BWI calculation diagram based on this DRI and the wear value obtained by the wear test.

[0007]

However, the excavation management method for a tunnel excavator based on the above-mentioned drilling index and bit wear index is not well known in Japan, and in addition to this, a DRI calculation diagram is required to obtain these values. At present, the optimum test method for obtaining the brittleness test value for application has not yet been established.

Further, the development of a brittleness test method capable of obtaining a brittleness value capable of appropriately evaluating the brittleness of the natural ground and accurately aiming at the stability of the ground and the efficiency of excavation work by various excavating machines has been developed. Is desired.

Therefore, the present invention has been made in view of such conventional problems, and obtains a brittleness value with which the brittleness of the ground can be properly evaluated, and the stability of the ground can be easily evaluated. Alternatively, it is an object of the present invention to provide a method for testing the brittleness of natural ground, which can easily improve the efficiency of excavation work by various excavating machines.

In addition, the present invention, in excavation work by a tunnel excavator in particular, accurately grasps the value of the brittleness value to be applied to the DRI calculation diagram, and through the DRI calculation diagram and the BWI calculation diagram, the tunnel excavator DRI or B closely related to the excavation efficiency of
It is an object of the present invention to provide a brittleness test method for natural rocks that enables easy calculation of WI.

[0011]

The present invention has been made in order to achieve the above object, and its gist is a brittleness test method used for evaluating the brittleness of a natural ground. A coarse-grained sample having a particle diameter of about 10 to 20 mm obtained by collecting from the above is packed in a mold, and a weight of a predetermined weight is dropped onto the coarse-grained sample in the mold from a predetermined height for a predetermined number of times. A coarseness sample is subjected to a sieve having a predetermined stitch size, and the brittleness value is obtained from the weight percentage of the crushed coarseness sample.

Here, in the above description, the coarse-grained sample used as a sample for the brittleness test is, for example, by crushing earth and sand or rock collected from the ground at the position to be investigated by various boring etc. It can be easily obtained.

In the brittleness test, the weight of the weight, the drop height of the weight, the number of drops, the mesh size of the sieve and the like can be appropriately designed.
0.5 kg of a coarse-grained sample having a particle size of about 10 to 20 mm, which was sieved using a sieve having a mesh size of IS standard of 9.5 mm and 19.0 mm, was packed in a mold, and a weight of 14 kg was placed in the mold from a height of 25 cm. The sample was vertically dropped 20 times, and then the crushed coarse-grained sample had a mesh size of 9.
It is preferable to pass through a 5 mm sieve and determine the brittleness value by the weight percentage passing through it.

According to the ground embrittlement test method of the present invention, a brittleness value suitable for evaluating the embrittlement degree of the ground is obtained, the stability of the ground is grasped, or various kinds of excavating machines are used. It is possible to improve the efficiency of the excavation work, and especially in the excavation work by the tunnel excavator, the DRI
Obtaining a value of the brittleness value suitable for application to the calculation diagram, calculating the DRI closely related to the excavation efficiency of the tunnel machine from this value, and further calculating the BWI through the BWI calculation diagram As a result, the tunnel excavator can be managed so that efficient excavation work can be performed, and the replacement time and endurance time of the cutter bit can be accurately grasped.

That is, it was obtained by the field test described later by the ground property at an arbitrary excavation position in the rock ground by the tunnel excavator and the ground embrittlement test method of the present invention for the rock sample collected from the excavation position. It was found that there was a certain correlation with the brittleness value, and the pure excavation speed at any excavation position in the rock ground by the tunnel excavator and the rock sample collected from the excavation position. DRI and BW according to the brittleness value obtained by
Since it was found that there is a close correlation with I, it is possible to easily evaluate the stability of the ground due to the degree of brittleness, and before performing excavation work with an excavating machine, for example, For soil or rock samples collected from each survey location by survey boring, etc., the brittleness value is obtained by the ground embrittlement test method of the present invention, and especially when the excavating machine is a tunnel machine, this brittleness value If the DRI and BWI are calculated from the data, and these values are plotted in a diagram, for example, in association with the sampling position, the workability of the excavating machine with the sampling position as the excavation position can be easily predicted, and the tunnel It is clear that the pure excavation speed by the excavator and the properties of the rock mass can be easily predicted, and therefore, the construction management of the excavation work can be appropriately performed by these.

The DRI is the value of DRI calculated from the DRI calculation diagram based on the brittleness value obtained by the brittleness test and the J value of the sea bar obtained by the miniature drill test. The wear index is
It is the value of BWI calculated from the BWI calculation diagram based on the wear value obtained by this DRI and the wear test.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The properties of the ground at an arbitrary excavation position by a tunnel excavator in rock ground and the rock samples taken from the excavation position are obtained by the ground embrittlement test method of the present invention. The brittleness value obtained by the brittleness test method according to the present invention on the correlation between the obtained brittleness value, the pure excavation speed of the tunnel machine at an arbitrary excavation position, and the rock sample obtained from the excavation position. The outline of the field test and the test result performed to clarify the correlation with DRI or BWI calculated from the above will be described.

As an example, this field test was conducted to confirm that it is effective to adopt the ground brittleness test method of the present invention when controlling the excavation work by the tunnel excavator. However, the brittleness test method of the present invention is not limited to the construction management of such a tunnel excavator, and can be used for managing the excavation work by other excavating machines and for evaluating the stability of the ground. You can also

<Outline of test> 1. Test sample The rock sample used was one of the TBM construction points in the TBM construction at the Yuda No. 2 tunnel on the Akita Expressway.
22 samples were taken every 10 to 20 m from the approximately 400 m section that is a hard rock area. Samples for brittleness test and abrasion test were granular rocks transported by belt conveyor after passing through crusher of TBM, and samples for miniature drill test were used by collecting rock mass in chamber of TBM. .

2. Brittleness test A brittleness test is performed according to the following method, and its outline is shown in FIG. a) From the collected granular rock sample 10, a coarse-grained shaving having a particle size of about 10 to 20 mm is sieved using a JIS standard 9.5 mm and 19.0 mm sieve. b) 0.5 kg of sieved coarse-grained rock sample is packed in a cylindrical mold 11 having an inner diameter of 10 cm. c) A pad 1 on the rock sample 10 packed in the mold 11.
2 is installed. d) The weight 13 of 14 kg is attached to the support 12 and the supporting rod 1
Sample 10 is crushed by vertically dropping 20 times from the position of 25 cm in height through 4. e) The crushed rock sample 10 is again mesh size 9.5 m
Sieve through the sieve and measure the weight of the sieve. f) Calculate the weight percentage of the rock sample 10 that has passed,
The brittleness of the rock sample is evaluated by using the obtained value as the brittleness value. g) In this test, the mold 11 had a structure as shown in FIG.

3. Miniature drill test A miniature drill test is performed according to the following method, and its outline is shown in FIG. a) A rock mass sample 20 of about fist size that has been collected is put in a mold 21 and fixed using gravel, crushed stone, or the like. b) The mold 21 containing the rock mass sample 20 is installed inside the mold receiver 23 in which the load cell 22 is installed. c) A drill bit 24 (drill material: tungsten carbide) is pressed into the fixed rock mass sample 20 from above with a pressing force of 20 kgf and rotated to penetrate. d) The penetration amount of the drill 25 is measured by the displacement meter 27 in units of 1/10 mm every 5 seconds and output to the data logger 26. The measurement is basically for 200 rotations. e) Using the measured penetration amount as the J value of the sea bar, the penetration degree of the drill in the rock sample is evaluated. f) If the entire length of the bit 25 penetrates before the drill bit 24 has rotated 200 times, the penetration amount per unit second is calculated from the test result, and the penetration amount is 200 from the relationship between the test time and the rotation speed of the drill. Calculate the amount of penetration equivalent to rotation. g) Further, as shown in FIG. 4, the drill bit 24 used in this test is mounted on the body 28 of the drill bit 24 having a diameter of 13 mm and a length of about 50 mm via a mounting jig 29, as shown in FIG. The drill 25 having a different shape is attached in a state of protruding 20 mm from the attachment jig 29. h) In this test, a mold 21 having a structure as shown in FIG. 5 was used, and a mold receiver 23 having a structure as shown in FIG. 6 was used.

4. Abrasion test An abrasion test is performed according to the following method, and its outline is shown in FIG. 7.

A) The collected granular rock sample is further ground into fine particles having a particle size of about 1 mm. b) Of 0.5 kg of finely divided rock sample, about half is spread as the abrasive 30 on the disk 32 of the test device 31,
The remaining sample 30 is packed in a feeder (supplementer) 33. The fine granular rock sample 30 as an abrasive is laid on a disk 32 in a circular band shape having a width of about 3 cm and a center radius of about 15 cm. c) Bit 34 before test (Material: Steel C scale 60)
Measure the weight of. d) Sample 3 in which the bit 34 is laid on the disk 32 in a strip shape
It is installed so that it comes into contact with the top of the 0.
Hold down with 5. e) The disc 32 is basically rotated 100 times. During this rotation, the fine rock sample 30 is continuously supplied from the feeder 33 to the disk 32 as an abrasive so that the material 30 is always inserted between the disk surface and the bit. f) After rotating the disc 32 a predetermined number of times, the bit 34 is removed and the weight thereof is measured again. g) Weight loss of bit after rotation compared to before rotation (m
The degree of wear of the rock sample is evaluated using g) as a wear value. h) In this test, as shown in FIG. 8, the bit 34 is formed by bending a lower end portion of a flat plate-shaped member having a height and width of 30 mm and a thickness of about 10 mm into a semicircular shape. use.

5. Calculation of DRI DRI is calculated from the DRI calculation diagram shown in FIG. In this diagram, the brittleness value obtained in the brittleness test is taken as the value on the horizontal axis, and the DRI set on the vertical axis is read using the J value of the sea bar obtained by the miniature drill test as a parameter. In addition, the DRI shows that the larger the value, the softer the ground,
The smaller the value, the harder the ground.

6. Calculation of BWI BWI is calculated from the BWI calculation diagram shown in FIG. In this diagram, the wear value obtained in the wear test is used as the value on the horizontal axis, and the BWI set on the vertical axis is read using the DRI as a parameter. In addition, BW
From the calculation method, I indicates that the larger the value, the harder the ground, and the smaller the value, the softer the ground.

<Test Results> 1. Relationship between brittleness value, J value of sea bar, and wear value FIG. 11 shows the result of plotting brittleness value and J value of sea bar against the TBM excavation position. From this figure, it is found that both values show almost the same change with respect to the TBM excavation position, and the brittleness value and the J value of the sea bar show large values in the section from the cumulative distance of 100 m to around 200 m. . From the properties of these two indicators, it can be judged that soft rocks are present in this section compared to the preceding and following sections. The opposite is true near 250 m. On the other hand, the results of plotting wear values are shown in FIG.
According to this, it is found that the wear value changes with respect to the TBM excavation position, opposite to the results of the above two tests. Taking into consideration that the wear value has the opposite property to the other values, the same tendency as in FIG. 11 is obtained.

2. Relationship between DRI and pure excavation speed FIG. 13 shows the results of plotting the DRI calculated by applying the brittleness value at each sampling point and the J value of sea bar to the calculation diagram against the TBM excavation position. The TBM excavation extension distance is shown on the horizontal axis, and the DRI is shown on the left vertical axis.
Further, the TBM excavation speed per unit thrust is plotted in the same figure. The TBM excavation speed is the TBM pure excavation speed per constant thrust thrust 1tf. The reason for making the thrust thrust constant in this way is to eliminate the influence of the machine and to compare it with the excavation speed due to only natural factors. Is. From the result of superimposing these values, it is found that there is a close correlation between the DRI and the TBM pure excavation speed.

3. Relationship between BWI and pure excavation speed The wear value and DRI at each sampling point are applied to a calculation diagram to calculate BWI, and the result of plotting such BWI against the excavation position is shown in FIG. 14. T on the horizontal axis
The BM excavation extension distance is shown, and the left vertical axis shows BWI. Further, in the same figure, as in FIG. 13, T per unit thrust is
The BM excavation speed is set on the right vertical axis and plotted. From the result of superimposing these values, it is confirmed that the BWI shows a transition that conflicts with the excavation speed. And BW
Considering the property of I, it is found that the BWI sufficiently corresponds to the change in the pure excavation speed due to the rock type and the hardness of the rock.

4. Relationship between BWI and amount of wear of cutter bit BWI is compared with the value that averages the amount of wear of each cutter bit per 1 km of rolling distance (circumferential distance by which the cutter bit cuts rock due to rotation of the cutter face). What was made to show is shown in FIG. From this graph, it can be confirmed that the BWI tends to increase in the section where the average cutter wear amount is large and tends to decrease in the section where the average cutter wear amount is small. That is, B
It turns out that there is a good correlation between WI and the wear properties of the cutter bit. In addition, it is considered that the largest amount of average wear in the range where the lapilli tuff is distributed is due to the mineral composition of the rock. For example, hard minerals such as quartz are abundant in basalt and abundant in lapilli tuff.

5. Conclusion From the above, according to the brittleness value obtained by the brittleness test method of the ground of the present invention, the cutting efficiency of the face face by the tunnel machine, that is, the nature of the ground related to the efficiency of the excavation work by various excavating machines It was found that it was possible to predict, and by using DRI or BWI calculated by applying such a brittleness value, it is possible to accurately grasp the change in the TBM pure excavation speed according to the change in the properties of the rocky ground, and the cutter bit It turns out that the replacement timing can be easily predicted.

[0031]

As described in detail above, according to the method for testing the brittleness of the ground according to the present invention, the brittleness value which can properly evaluate the brittleness of the ground is obtained, and the stability of the ground is improved. It is possible to easily evaluate or easily improve the efficiency of excavation work by various excavating machines.

Further, particularly in the excavation work by the tunnel excavator, the value of the brittleness value to be applied to the DRI calculation diagram is accurately grasped, and the excavation of the tunnel excavator is performed through the DRI calculation diagram and the BWI calculation diagram. Easily calculate DRI or BWI, which has a close correlation with efficiency, and use this to accurately manage changes in the TBM pure excavation speed according to changes in the properties of the ground, replacement time of cutter bits, etc. It is possible to easily improve work efficiency.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an outline of a preferred example of a brittleness test.

2A and 2B are explanatory views showing the shape of a mold used in the brittleness test of FIG. 1, in which FIG. 2A is a top view and FIG. 2B is a front view.

FIG. 3 is an explanatory diagram showing an outline of a preferred example of a miniature drill test.

4A and 4B are explanatory views showing the shape of the drill bit used in the miniature drill test of FIG. 3, in which FIG. 4A is a top view, FIG. 4B is a front view, and FIG.

5A and 5B are explanatory views showing the shape of a mold used in the miniature drill test of FIG. 3, in which FIG. 5A is a top view and FIG. 5B is a front view.

6A and 6B are explanatory views showing the shape of a mold receiver used in the miniature drill test of FIG. 3, in which FIG. 6A is a top view and FIG. 6B is a front view.

FIG. 7 is an explanatory diagram showing an outline of a preferred example of a wear test.

8A and 8B are explanatory views showing the shape of the bit used in the wear test of FIG. 7, where FIG. 8A is a top view, FIG. 8B is a front view, and FIG. 8C is a side view.

FIG. 9 is a chart showing an example of a DRI calculation diagram.

FIG. 10 is a chart showing an example of a BWI calculation diagram.

FIG. 11 is a chart in which brittleness values and sea bar J values at each excavation position are plotted.

FIG. 12 is a chart in which wear values at each excavation position are plotted.

FIG. 13 is a chart showing the correlation between DRI and TBM pure excavation speed at each excavation position.

FIG. 14 is a chart showing the correlation between BWI and TBM pure excavation speed at each excavation position.

FIG. 15 is a chart showing the correlation between BWI and average cutter wear amount at each excavation position.

[Explanation of Codes] 10 Coarse-grained rock sample 11 Mold 12 Abutment base 13 Weight 14 Support bar 20 Rock mass sample 21 Mold 22 Load cell 23 Mold receiver 24 Drill bit 25 Bit 26 Data logger 27 Displacement meter 28 Main body 29 Mounting jig 30 Fine particle Rock sample (abrasive) 31 Testing device 32 Disk 33 Feeder 34 Bit 35 Weight

Claims (2)

[Claims] 1. A brittleness test method used to evaluate the brittleness of a natural ground, which comprises packing a coarse-grained sample having a particle size of about 10 to 20 mm obtained from a target ground into a mold. After dropping a weight of a predetermined weight on the coarse-grained sample in the mold a predetermined number of times from a predetermined height, the coarse-grained sample is sieved with a predetermined stitch size, and the brittleness value is obtained from the weight percentage of the crushed coarse-grained sample. A method for testing brittleness of natural rocks, which is characterized by 2. JIS standard 9.5 mm and 19.0 mm
Approximately 10 particle size sieved using a mesh size sieve
0.5 kg of a coarse-grained sample of ~ 20 mm is packed in a mold,
A weight of 14 kg is vertically dropped 20 times from a height of 25 cm, and then the crushed coarse-grained sample is passed through a sieve having a mesh size of 9.5 mm, and the brittleness value is determined from the weight percentage passed through the sieve. Item 1. The brittleness test method for natural rocks according to Item 1.