JPH0438441A - Simple bed rock shearing test device - Google Patents

Abstract

PURPOSE:To simplify testing work by setting a frame provided with a vertical direction pressing means and a shearing direction pressing means over a test piece and fixing it with anchor bolts. CONSTITUTION:A bed rock 31 is cut out into blocks 32 in advance and arranged with concrete to form a test piece 34. Anchor bolts 35 are embedded at both sides of the test piece to fix the frame 2 of a test device 1. Next, the test piece 34 is sheared pressing it downward with a vertical direction pressing means 10 and pressing a slanting surface 34a with a shearing direction pressing means 20. The acting loads are measured with the load meters placed on each means. To carry the test device, the frame 2 itself, the vertical direction pressing means 10 and the shearing direction pressing means 20 are disassembled so that they can be carried with hands.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement in a testing device for determining the shear strength of rock mass.

(Prior Art) When carrying out civil engineering works such as dams and tunnels, it is extremely important to quantitatively understand the strength of the rock at the relevant location.

Among the above-mentioned strengths, methods for determining shear strength include a sampling method and an in-situ testing method.

That is, the sampling method is a method in which a sample is cut out from the bedrock at the location, taken back, and run through a testing machine in a testing room. However, with this method, it is difficult to cut out good-shaped samples, and test accuracy is said to decrease because moisture content changes during the time the samples are returned.

Therefore, it is desirable to conduct a test directly at the location (this is called an "in-situ test"), and a shear test is performed by cutting out a part of the rock into a square block shape and pushing this with a hydraulic jack etc. .

FIG. 6 is a diagram showing the implementation of a conventional in-situ test. In the in-situ shear test, a tunnel 101 of approximately 2 x 2 m is dug, a test specimen 103 is cut and formed on the floor 102 of the tunnel, and the ceiling 104 of the tunnel is used as a starting point. Test specimen 1 with vertical jack 105
03, the test specimen 103 is pressed with a horizontal jack 107 starting from the tunnel wall 106, and the load cell 108
Measure the acting load.

(Problem to be Solved by the Invention) The above test is generally conducted on at least four rock masses of the same rock mass classification. However, since the above-mentioned conventional tests are expensive per test, it is difficult to increase the number of samples, and it is difficult to calculate highly reliable shear strength.

Furthermore, in recent years, there has been an increase in the number of cases in which structures are supported on low-grade rock such as sedimentary rock or weathered granite that has low shear strength.

Therefore, the present invention aims to simplify the test equipment and increase the number of samples.

(Means for Solving the Problems) In order to achieve the above object, the present invention includes a frame installed over a test specimen, a vertical pressing means attached downward to the frame, and a vertical pressing means attached to the frame substantially laterally. A simple rock shear test device is constructed from the shear direction pressing means.

(Function) Rock is cut into blocks in advance and shaped to create a test specimen. Anchor bolts are buried on both sides of this test specimen, and the frame of the test device is fixed with these anchor bolts.

Next, while pressing the specimen downward with the vertical pressing means, the specimen is pushed and sheared with the shearing pressing means.

The acting load at this time is measured with a load meter attached to each means.

To transport the test device, the frame itself, the vertical pressing means, and the shearing direction pressing means are disassembled and transported manually.

(Example) Embodiments of the present invention will be described below based on the accompanying drawings.

! Fig. 1 is a front view of a simple rock shear test device according to the present invention, Fig. 2 is a view taken in the direction of the I+ arrow in Fig. 1, and Fig. 3 is a view II in Fig. 1.
It is a view taken along the I arrow.

The simple rock shear test device 1 (hereinafter abbreviated as “shear device 1”) has base plates 2a, 2a (see Fig. 2).
The upper end of the leg members 2b and 2b that stood up from the top beam 2c
A hydraulic cylinder 11 is attached to a frame 2 that is connected to form a gate shape.
A vertical pressing means 1o consisting of a load sensing part 12 and an upper pressing part 13 is attached, while tie beams 3, 3, 3.3 (see FIG. 3) are extended horizontally from the lower parts of the members 2b, 2b. A shearing direction pressing means 20 consisting of a hydraulic cylinder 21, a load detecting section 22, and a lateral pressing section 23 is attached to the tie beam 3.

The load detection section 12.22 is connected to a hydraulic cylinder 11.21.
This device continuously measures the applied pressing force, for example, it has a built-in ferromagnetic material, this ferromagnetic material is mechanically strained, the magnetization characteristics change according to this strain, and this change is converted into electric current. The data is then output to the outside.

Further, the top pressing section 13 and the horizontal pressing section 23 have rollers 13a and 23a at their tips, respectively, and convert the pressing force into a distributed load.

In order to allow the frame 2 to be carried by hand, the leg members 2b and the top beam 2c are removably connected with bolts and nuts BNI, and the one leg member 2b and the tie beam 3 are removably connected with bolts and nuts BN2. Furthermore, the other end of the tie beam 3 is removably connected with a bolt and nut BN3.

The operation of the shearing device constructed as described above will be described next.

FIGS. 4(a) to 4(C) are explanatory diagrams of cutting out the test specimen. As shown in FIG. 4(a), the rock mass 31 is excavated and approximately 2
0cmx 20cmx (height) 10cm block 3
Cut out 2. For excavation, it is preferable to use manual chisel digging.

Next, as shown in FIG. 4(b), a concrete formwork 37 is placed over the block 32, concrete is poured, etc., and a predetermined thickness of concrete 33 is adhered to the block 32, thereby forming the illustrated test specimen 34. do. Note that the negative side surface is an inclined surface 34a inclined at 15 degrees with respect to the perpendicular line.

Furthermore, anchor bolts 35 are buried on both sides of the block 32 (FIG. 4(C)).

Next, as shown in FIG. 5, which is an explanatory diagram of the operation, the shearing device 1 of the present invention is brought in, its frame 2 is placed over the test specimen 34, and the base plate 2a is placed.

2a (see Fig. 1) to the anchor bolts 35... with nuts.

Next, pressure oil is supplied from a hydraulic pump unit (not shown) to the hydraulic cylinder 11 shown in FIG.
4 was loaded with a constant vertical load, the inclined surface 34a of the test specimen 34 was gradually pressed by the shear direction pressing means 20 to cause shear failure.

During this time and at the time of failure, the vertical load N and shear load T are measured with a pen recorder 36, and the word value is determined using the following formula.

Shear core force τ=Tcosθ/A Normal stress a= (N+T sinθ)/A where A
The area θ of the sheared cross section is 15°. After completing the test at one location, the bolt, nut BNI, BN2
Then, loosen the BN3, separate the frame 2, tie beam 3, and hydraulic cylinders 11 and 21, and transport them manually.

These are then moved to the next test specimen and assembled.

Hereinafter, the shear test may be performed sequentially.

The present invention is also characterized by embedding anchor bolts.

The anchor bolts are easy to install, so they can be constructed in parallel with the excavation and hand chiseling shown in Figure 4 (a), and the mortar curing for the anchor bolts is done in parallel with the concrete curing shown in Figure 4 (b). There is no time loss because the tests can be performed in parallel, and the wire test time can be significantly shortened because the test pieces can be manufactured in small sizes one after another and the shearing device can follow suit.

Note that the anchor bolt 35 is not limited to this, and the anchor bolt 35 is not limited to this.
Anchor metal fittings such as an anchor frame or reed cover embedded in the base may be used instead.

(Effects of the Invention) As described above, the present invention conducts rock shear tests using a portable shearing device whose frame is fixed with anchor bolts and which can be disassembled and assembled freely, thereby eliminating the need for conventional tunnel excavation. Because it allows testing even in open air without
Testing has become easier and the number of samples can be doubled, making it possible to calculate the shear strength of rock at a higher level.

[Brief explanation of drawings]

Fig. 1 is a front view of the simple rock shear test device according to the present invention, and Fig. 2 is the I! of Fig. 1! Fig. 3 is a view taken from the arrow III in Fig. 1, Fig. 4 (a) to (c) are explanatory views of cutting out the test specimen, Fig. 5 is an explanatory view of the action, and Fig. 6 is the conventional original position. It is an implementation diagram of the test. 1... Simple rock shear test device (shear device) 2...
-Frame 10...Vertical direction pressing means 20...Shearing direction pressing means 31...Rock 32...Block 34...
・Test specimen 35... Anchor fitting Fig. 2 %-J No.

Claims (1)

[Claims] A simple rock shear test device that shear-ruptures a test specimen made by cutting and shaping the rock mass to be tested into blocks in advance, and this simple rock shear test device comprises a frame installed over the test specimen; The frame is composed of a vertical pressing means attached downward to the frame, and a shearing direction pressing means attached to the frame substantially laterally, and the frame is fixed to the rock via anchor fittings buried in the rock, and A simple rock shear testing device characterized by a frame that can be disassembled so that it can be transported by hand.