JPS5811832A - Method and device for measuring original point of tensile stress - Google Patents

Abstract

PURPOSE:To adequately grasp the extent of reinforcement of a cut or raised slope by planting, by bumerically measuring the growing conditions of the roots of plant. CONSTITUTION:Plant as a body to be tested is selected and arranged in a prescribed shape. The plant is all cut while the stem part 41 is left to a several cm height. A molding flask 11 is impanted nearly to the boundary between its upper and lower cylinders 31 and 33 in such a way the plant is nearly in the center of the flask 11. Then, a molding material 42 is flowed into the cylinder 31 and cured. As the molding material 42, plaster is used favorably. Thus, the body to be tested is put in order, and then the molding part is drawn up by a jack. For this purpose, a screw jack is expanded nearly to its limit and lowered gradually to generate tensile force. Then, a stress and a strain value are read according to a predetermined schedule.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides, but is not particularly limited to, a method for measuring the tensile strength of roots of various plants grown on cut or embankment slopes, and This article relates to the test equipment used for this purpose.

In order to protect the slope from being eroded by cutting or embanking, a method of covering the slope with plants, so-called "vegetation work" is often performed. When constructing vegetation works, it is extremely important whether or not the plants will take root on the slope, so measurements of soil hardness, soil chemical properties, and surrounding environment surveys are carried out before construction. After that, measurements such as vegetation density, grass height, weight per unit area, and vegetation coverage are carried out.

By the way, the degree of slope reinforcement using vegetation works is largely influenced by whether the plant roots extend deep into the ground and whether the roots are in good growth condition.

In other words, it depends more on the conditions underground than on the surface. However, the above-mentioned conventional measurements after the construction of vegetation works only provide a superficial indication of the growth state of the plants, and cannot be used to quantify the extent to which the slope has been reinforced by the vegetation. That is difficult.

In addition, Shirasu, which is widely distributed in southern Kyushu, and Masago, which is a weathering agent for granite, are generally called special tops, and there are many parts that have not been elucidated by conventional soil engineering, so it is necessary to test their tensile strength. At present, methods and devices have not yet been sufficiently researched and developed.

The present invention has been made in view of the actual state of the prior art as described above, and its purpose is to quantitatively measure the growth state of roots of plants that have been cut or grown on embankment slopes, etc. It is possible to accurately grasp the degree of reinforcement of a slope by vegetation, or to quantitatively grasp the stability of unsaturated (above the groundwater level) soil such as whitebait and sand. It is an object of the present invention to provide an in-situ measurement method and an apparatus used to carry out the method.

Hereinafter, the present invention will be described in detail based on the drawings, taking as an example the case of a vegetation plate tensile stress test in which the specimen is a stem or root hair of a plate.

FIG. 1 is a schematic diagram showing an example of a measuring device used when carrying out the method of the present invention. In the figure, each device is installed on horizontal ground, but in reality, the growing point of the plant being tested is a cut-out or embankment slope, so it is often installed on a slope. Therefore, measures have been taken to allow installation on any slope.

Now, this device consists of a tension operation section 1 and a stress/strain measurement section 2. The tension operation unit 1 includes a screw jack 6 placed on a base 4 on which a reaction force is taken by a plurality of (four in this embodiment) anchor rods 3, and a screw jack 6 placed on the base 4.
It has a structure in which a small tower 6 is erected at the top, and a pulley 7a is provided at the top of the tower. In relatively soft ground, the anchor rod 3 has a cone 8 attached to the tip and is fixed by driving, and in relatively hard ground, a screw point for sounding is attached to the tip and is inserted and fixed by rotation. Ru. The base 4 is adjusted to be as horizontal as possible by operating the height adjustment mechanism 9.

The stress/strain measurement unit 2 uses a molding material to fix a tripod 10, several pulleys 7b and 7c on the sides and top, and the stem or exposed root hairs of a plant to be tested. A cylindrical mold formwork 11 serving as a formwork, and the mold formwork 1
1, and a strain gauge 15 mounted on a fixed bar 14 horizontally supported by a plurality of (two in this embodiment) iron piles 13. The stress detector 12 and the screw jack 5 are connected by a wire rope 16 stretched via pulleys 7a, 7b, and 7c.

The iron pile 13 is driven into a point outside the area of influence due to the behavior of the specimen, and the fixed bar 14 made of a constant-feed section steel is adjusted by a height adjustment mechanism 17 so as to remain horizontal. A strain gauge 15, such as a dial gauge, is attached to a magnet base 18, which is held on the fixed bar 14 by magnetic attraction. The stress detector 12 passes through the frame 21 of the first frame 21 such that the lower branch 20 is connected to the mold frame 11 and the upper branch 22 of the frame 21 of the spear 1 and connects to the side column 23.
The frame 24 of spear 2, which is slidable, and the frame 2 of 171
The second frame 2 consists of a proving ring 26 attached between the upper branch 22 of the spear 1 and the lower branch 26 of the frame 24 of the spear 2.
One end of the wire lobe 16 is attached to the upper branch 27 of 4. In other words, the stress detector 12 is configured to use the proving ring 26 to convert tensile stress into compressive stress for detection. Therefore,
By replacing the proving ring according to the situation, various strengths and precisions can be accommodated.

Next, the cylindrical mold formwork 11 has seven flange 30 at the upper end.
It has a two-stage structure consisting of a two-part cylinder 31 that is screwed into the cylinder 31 and a lower cylinder 33 that has a cutting edge 32 at the lower end, and both are loosely fitted at their abutting ends, and the upper cylinder 31
A mold retaining rod 34 is inserted through the lower end of the mold retaining rod 34 in the diametrical direction thereof. A bolt insertion hole 35 is provided in the flange 30, and as shown by the phantom line, the flange 30 is provided with a bolt insertion hole 35.
It will be fixed to the lower branch 20 of No. 1 with bolts and nuts. Here, the function of the mold material holding rod 34 is to prevent the mold material from falling off from the upper cylinder 31 of the mold frame 11. In other words, the molding material is poured into the molding material, and after hardening, the mold is pulled out. At this time, the tensile stress of the roots is counteracted by the frictional force between the inner surface of the molding material and the molding material. . However, since this frictional force alone may not be enough to withstand the tension of the roots, several efforts have been made to integrate the mold formwork and molding material to increase the resistance force.

The measurement method is as follows. First, a plant to be tested is selected and arranged into a predetermined shape. For example, as shown in FIG.
Reap all but 1. Then, the mold frame 11 is driven to the vicinity of the boundary between the upper cylinder 31 and the lower cylinder 33 so that the plant is positioned approximately in the center of the mold frame 11. Thereafter, a molding material 42 is poured into the upper cylinder 31 and hardened. As the molding material 42, gypsum is suitable. In a preliminary test, the strength after pouring plaster into the mold and allowing it to harden for one hour was 200K9 or higher when it was tensile broken, confirming that it had sufficient strength in this test. has been done.

Now, after preparing the specimen in this way, measurements are performed using the apparatus configuration shown in Figure 1. First, the screw jack 5 is extended to near its upper limit and then gradually lowered to create tension.

Then, the values of stress and strain (the amount of lifting of the mold formwork) may be read in accordance with a predetermined schedule.

An example of the measurement results is shown in Figure 4. This graph shows the measurement results for Hirohanokonokaguza at a certain point.
In the same figure, curve A is the measurement result at the ground surface as described above, and curves B and C are respectively 10Cr below the pond surface.
These are the results of measurements taken by excavating up to n and 20 CrrL, exposing the root hairs, and hardening them with plaster. Note that, as shown in this embodiment, the mold formwork 11 has a two-stage structure, with the lower cylinder 3.3 being driven into the ground, and the upper cylinder 3.3 being driven into the ground.
to fill with plaster and pull out the upper cylinder 31,
If configured as follows, the following advantages occur and favorable results can be obtained. First of all, roots have a considerable spread not only in the depth direction but also in the horizontal direction, and if they were to be subjected to a test as they were, both stress and (9) - equipment would be extremely large and difficult to handle. This will improve this point, and the lower cylinder 33 will insulate the ground near the specimen from the surrounding ground, keeping the cross-sectional area of the shear plane constant, so data with good reproducibility can be obtained. In addition, if the upper cylinder 31 and lower cylinder 33 are of an integral structure, the surrounding friction of the soil will act on the mold frame at the implanted part, making it easier to compare with other specimens. However, since the two-stage separated structure as described above is used, such a problem does not occur.

The above explanation has been given using the case of tensile stress measurement of vegetation plates as an example. ) Can also be applied to measuring tensile stress on soil. Masago soil generally has low tensile strength, but
Some materials that are extremely weathered have a small amount of tensile strength. It is significant to investigate the tensile strength because the stability of the soil is determined by slight differences in the tensile strength. The method and apparatus shown in the above embodiments can be applied as they are to the measurement of these special tensile strengths.

Since the present invention is configured as described above, it is possible to quantitatively measure the growth state of roots of plants grown on cut or embankment slopes. The degree of reinforcement can be accurately determined, and highly accurate information that cannot be obtained with conventional technology can be obtained in terms of evaluating slope strength and obtaining basic data for designing and constructing vegetation works. In addition, it is possible to obtain numerical data with high reproducibility for areas that are generally called special areas such as whitebait and masago that are difficult to understand with conventional soil engineering, and we have carried out numerous tensile strength measurements on these special areas.
If implemented, it will have many excellent effects, such as leading to the development of new fields of soil engineering.

[Brief explanation of the drawing]

2.1 is a schematic diagram showing an embodiment of the device according to the present invention,
Figures 3 and 4 are graphs showing examples of measurement results. DESCRIPTION OF SYMBOLS 1... Tension operation part, 2... Stress detection part, 3... Anchor rod, 4... Base, 5... Screw jack, 11... Mold formwork, 12... Stress detection Part 1
5... Strain meter. Patent Applicant: Yudo Omata, Representative, Applied Geological Survey Office, Co., Ltd.
Jodo Shigemi
Araki Tomoyuki Suke 3 Figure 4 Day appetizer! (kg) Weight 1=Su〕≧187

Claims (1)

[Claims] 1. After arranging a cylindrical mold frame so that the center of the specimen is located approximately at the center, pouring a molding material into the mold frame and hardening it and fixing it to the specimen, A tensile stress in-situ measuring method characterized in that the tensile strength of the specimen is determined by pulling up the mold part with a jack and measuring the load and amount of lifting at that time. , 2. A jack placed on a base whose reaction force is taken by multiple anchor rods, a cylindrical mold formwork that serves as a formwork for fixing the specimen with mold material, and a stress connected to the mold formwork. It includes a detector, a wire lobe that connects the stress detector and the jack, and a strain meter that is mounted on a fixed bar positioned by a plurality of stakes and measures the amount of lift of the mold formwork. Tensile stress in-situ measuring device. 3. The cylindrical mold formwork has a two-stage structure of an upper cylinder having a flange at the upper end and a lower cylinder having a cutting edge at the lower end, and the upper cylinder and the lower cylinder are loosely fitted at their abutting ends. , and a molding material holding rod is inserted through the lower end of the upper cylinder in the diametrical direction thereof.