JPH08247913A - Equal volume shear test equipment - Google Patents

Abstract

PURPOSE: To enable direct testing of the shear strength of an earth sample at the site and thereby to obtain the result of a test approximating extremely to the state of the actual natural ground and raised earth, by determining directly the equal volume shear strength of the ground at the original position by adding functions of vertical displacement measurement by a vertical pressing device and fine adjustment of a vertical load to site large-sized shear test equipment. CONSTITUTION: The surrounding ground is dug in prescribed dimensions (30×30×15cm approximately) and an earth sample S raised upward integrally with the original ground is prepared. The sample S is passed through an opening part 2 and a holding-retaining frame 3 and a base 1 is provided on the ground around it. A loading plate 12 being set on the sample S, a vertical pressing device 14, a pressing force measuring unit 16 and a vertical pressurizing device 17 are provided thereon with a slide bearing 13 interposed and the upper end of the device 17 is engaged with a reaction force support 21. While the sample S is made compact under a prescribed pressure and kept in a pressurized state by operating the device 17, a lateral pressing device 6 is operated to extend and the frame 3 is pressed by a pressing rod 10. The vertical displacement of the device 14 for maintaining an equal volume is monitored and regulated by a plurality of vertical displacement meters 19 and the pressurizing force is detected by the measuring unit 16. The pressing force by the device 6 is detected by a pressing force measuring unit 8, corresponding to the shift of the frame 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an equal volume shear tester for measuring shear strength of soil such as natural ground and compacted embankment while maintaining an equal volume on site and indoors. is there.

[0002]

2. Description of the Related Art Generally, in order to secure safety against landslides in embankments, it is necessary to carry out a shear strength test according to the depth of soil and the state of rolling compaction at the site.

Conventionally, a constant-pressure one-sided shear test device is known as a device capable of performing a shear test of soil on site.

As a shear test device for testing indoors, there is also known a device that uses a slight pressurizing device to perform an equal volume one-plane shear test on a small sample of at most about 10 cm cubic.

[0005]

In the conventional on-site shear tester, constant pressure shearing is generally performed on soil samples with a constant top load, and it is not possible to perform shearing tests under the same volume conditions on site. Therefore, there is a problem that an accurate test result cannot be obtained due to expansion or contraction of the soil sample during the test.

Further, the conventional apparatus for testing indoors cannot be used for in-situ measurement, and because the sample is small, it cannot be tested on soil containing gravel. The pressurizing device is also light and the soil sample is small. In addition, there is a problem that the reliability of the test result is poor because the state changes during the ordering from the site.

[0007]

In order to solve the above-mentioned conventional problems, the present invention has a base 1 provided with an opening 2 through which a soil sample S passes, and a soil sample S protruding upward from the opening 2.
The storage holding frame 3 is formed in a frame shape for storing and holding the storage holding frame 3 slidably installed along the slide guide 4 provided on the base 1, and fixed on the base 1 rearward in the sliding direction of the storage holding frame 3. Then, the lateral pressing device 6 having the pressing rod 7 projecting toward the rear end surface of the storage holding frame 3 and the pressing force rod is attached to the tip of the pressing rod 7 and the pressing rod is attached to the tip in the measuring direction. Device 8 and horizontal displacement meter 11 installed on the base 1 in front of the storage and holding frame 3 in the sliding direction.
And a loading plate 12 placed on the soil sample S stored in the storage holding frame 3, and a thrust bearing 13 provided on the loading plate 12 via a thrust bearing 13, and a vertical pressing force with the pressing operation rod 15 directed vertically upward. The device 14 and the vertical pressurizing device 17, which is attached to the tip of the pressing operation rod 15 via the pressing force measuring device 16 and applies a downward pressing force vertically, and the vertical pressing device 14 or the displacement of the loading plate 12 in the vertical direction. A vertical displacement meter 19 for measurement, an equal volume shear test device including a stopper 20 provided at a position where the portion of the pressing device 14 on the front side in the sliding direction of the storage holding frame 3 can be locked, and the soil sample S. A base 1 provided with an opening 2 through which the through-hole 2 and a frame body for accommodating and holding the soil sample S projecting upward from the opening 2 are formed and slidably installed along a slide guide 4 provided on the base 1. Done The storage holding frame 3, the lateral pressing device 6 fixed to the rear base 1 in the sliding direction of the storage holding frame 3, and the pressing operation rod 7 protruding toward the rear end surface of the storage holding frame 3, and the pressing operation rod. Pressing force measuring device 8 attached to the tip of 7 and a pressing rod attached to the tip in the measuring direction
A horizontal displacement meter 11 installed on the base 1 in the front of the storage holding frame 3 in the sliding direction, a loading plate 12 placed on the soil sample S stored in the storage holding frame 3, and a loading plate 12 on the loading plate 12. A vertical pressing device 14 installed via a thrust bearing 13 and having a pressing operation rod 15 directed vertically upward, and a pressing force applied vertically downward attached to the tip of the pressing operation rod 15 via a pressing force measuring device 16. A vertical pressure device 17 for
A vertical displacement gauge 19 for measuring the vertical displacement of the vertical pressing device 14 or the loading plate 12, a reaction force support body installed at the upper end of the pressurizing device 17, and a reaction force support body installed directly below the storage holding frame 3, The present invention proposes an equal volume shear test device including a storage / holding frame 3 through an opening 2 and a soil sample receiving box 24 constituting a series of soil sample storage spaces.

[0008]

[Operation] By adding the functions of vertical displacement measurement and fine adjustment of vertical load to the on-site large shear test equipment, it becomes possible to directly obtain the isochoric shear strength of the in-situ ground, and large soil samples can be used. Therefore, a test can be performed on a material containing gravel, and the reliability of the test result is improved.

By attaching a vertical load reaction force support, a soil sample receiving box and the like to the in-situ device, the in-situ device can be easily diverted for indoor testing.

[0010]

1 to 3 show an embodiment of an in-situ volume equal-volume shearing device according to the present invention, in which a base 1 has a rectangular parallelepiped soil projecting upward from an opening 2 provided therein. A storage and holding frame 3 formed in the shape of a rectangular frame for housing the sample S and surrounding the sample S is slidably installed along a slide guide 4 provided on the base 1, and the rear portion of the base 1 in the sliding direction. A lateral pressing device 6 having a constant pressing speed such as a screw jack is attached to the fixed wall 5 fixed to the upper side with its pressing operation rod 7 directed toward the rear end surface of the storage holding frame 3 in the sliding direction.

A pushing force measuring device 8 such as a force meter for measuring the pushing force is attached to the tip of the pushing rod 7 of the lateral pushing device 6, and is further provided on the base 1 at the tip in the measuring direction. A push rod 10 slidably inserted into the support guide 9 is attached, and the tip end of the push rod 10 is brought into contact with the slide direction rear end face of the storage holding frame 3 via a cushioning material, and the storage holding frame 3 is held inside the storage holding frame 3. The soil sample S is pushed together with the soil sample S in the forward direction to shear the soil sample S from the original ground.

The base 1 on the front side in the sliding direction of the storage holding frame 3
A horizontal displacement gauge 11 such as a dial gauge for measuring the horizontal displacement accompanying the pushing movement of the storage holding frame 3 is installed on the upper side.

On the soil sample S stored in the storage holding frame 3, a loading plate 12 formed in conformity with the shape and size of the upper surface of the soil sample S is placed at the time of measurement.

A vertical pressing device 1 such as a screw jack is mounted on the loading plate 12 via a thrust bearing 13.
4 is mounted with its pressing operation rod 15 facing vertically upward, and pressing force is applied vertically downward to the tip of the pressing operation rod 15 capable of finely adjusting the advancing / retreating operation via a pressing force measuring device 16 such as a force meter. A vertical pressure device 17 such as a hydraulic jack to be applied is installed.

A support member 18 fixed to the substrate 1 or the like is installed around the vertical pressing device 14 or the loading plate 12, and the vertical displacement of the vertical pressing device 14 or the loading plate 12 is measured on the support member 18. A vertical displacement gauge 19 such as a dial gauge is installed.

A stopper 20 is provided on the base 1 for locking the portion of the pressing device 14 on the front side in the sliding direction of the storage holding frame 3, and the vertical pressing device is provided along with the horizontal displacement accompanying the pushing movement of the storage holding frame 3. We support 14 so that 14 does not move.

A reaction force support body 21 such as a crawler machine body of an on-site civil engineering work machine is brought into contact with or attached to the upper end of the pressurizing device 17, for example, as shown in FIGS.

Next, FIGS. 7 and 8 show an embodiment of the indoor shear test apparatus. The base 1 having the same device structure as the in-situ shear test apparatus is mounted on the base 22. It is horizontally installed while being supported by the installed support leg 23 and soil sample receiving box 24.

The soil sample receiving box 24 is installed immediately below the storage / holding frame 3 in the normal position before the movement, and constitutes a series of soil sample storage space with the storage / holding frame 3 through the opening 2, and the soil sample storage box 24 is provided in the interior thereof from the site. The collected soil sample S is stored.

On the base 22, a reaction force support body 27 made of a horizontal steel material is supported by a column 26 which is erected on a horizontal member 25.
Is attached to the reaction force support 27,
Is mounted at the upper end.

A reaction force support 27 supported by a column 26 similar to the above may be installed on the base 1 of the in-situ shear test apparatus shown in FIGS.

In the above-mentioned structure, first, in the in-situ shear test, a protective frame for preparing the soil sample S is driven into the site ground, and the surrounding ground is excavated in a predetermined range to remove the protective frame, and then integrated with the original ground. Soil sample S raised above
Create

In this case, the soil sample S has a size that allows a shear test of soil containing general gravel, for example, a vertical length,
It is preferable that the width and height are around 30 cm × 30 cm × 15 cm or more, and if this is the case, mixing of gravel of about 63 mm or more is acceptable, and the size of the storage holding frame 3 depends on the size of the soil sample S. Also set.

Then, the soil sample S is passed through the opening 2 and the storage / holding frame 3, the base 1 is set on the surrounding ground, a loading plate 12 is placed on the soil sample S, and a thrust bearing 13 is further mounted thereon. Through vertical pressing device 14, pressing force measuring device 1
6 and the vertical pressure device 17 are installed, and the vertical pressure device 1
The upper end of 7 is locked to the reaction force support body 21 such as the crawler machine body shown in FIGS.

In this state, the pressurizing device 17 is operated to consolidate the soil sample S at a predetermined pressure, and when the compacted condition is almost settled (for example, after 30 minutes), the lateral pressing device is maintained while maintaining the pressurized condition. 6 is extended, and the storage rod 3 is pressed by the pressing rod 10.

At this time, the soil sample S receives the pressing force and expands and floats, or contracts and contracts. If the soil sample S is left unattended, it cannot maintain an equal volume. Alternatively, the vertical displacement of the vertical pressing device 14 is constantly monitored by a plurality of vertical displacement gauges 19 (the average value of the detected values is input to a personal computer to monitor and record), and when any tendency of ups and downs is detected, the vertical pressing device 14 is detected. 14 is adjusted forward or backward by a mechanical adjusting means by manual or electrical control, and the pressurizing force of the vertical pressurizing device 17 is increased or relieved to suppress ups and downs and maintain an equal volume.

The pressing force at this time is detected by the pressing force measuring device 16 over time and input and recorded in the personal computer.

The pressing force of the lateral pressing device 6 is always detected by the pressing force measuring device 8 and input and recorded in the personal computer.
The horizontal displacement gauge 11 monitors and records the movement of the storage and holding frame 3 (inputs the detected value to a personal computer to monitor and record), and when the movement of the storage and holding frame 3 within a predetermined range is detected, the lateral pressing device 6
Detect the pressing force of and then stop the operation.

A required number of soil samples S are prepared in accordance with the purpose of the test, and the load of the vertical pressurizing device 17 is changed, and the test is repeated by the same operation as described above under the condition that the pressure density is different.

Next, in the laboratory test, the apparatus shown in FIGS. 7 and 8 was used.
A sample with a height slightly higher than in the original position of about 30 cm × 30 cm × 30 cm in width and height is used, and this is loaded into a series of storage spaces of the soil sample receiving box 24 and the storage / holding frame 3, The soil sample receiving box 24
The soil sample S is sheared between the storage holding frame 3 and the storage holding frame 3, and the measurement result at that time is detected and recorded in the same manner as above.

The conventional constant pressure shear test can also be carried out by the apparatus of the present invention.

As shown in FIG. 9 by the above test apparatus, the correlation between the vertical stress σ of the vertical pressing device 17 through the vertical pressing device 14 and the shear stress τ of the lateral pressing device 6 and FIGS. The relationship between the shear displacement and the shear stress τ of the soil sample S in various states shown in 12 is known, and based on this, the shear strength of the soil in each portion such as the embankment and its characteristics can be known.

[0033]

As described above, according to the present invention, the shear strength of a soil sample can be directly tested on site while maintaining an equal volume, and an accurate test that is extremely close to the actual state of natural ground or embankment can be performed. The result can be obtained.

Further, since the storage and holding frame for soil samples can be enlarged, it can be applied to a wide range of soils from fine-grained soil to gravel soil, and accurate measurement results can be obtained with large soil samples. .

By attaching a small number of additional members to the device for the current position, it becomes possible to perform an equal volume shear test in a room,
It is economical and rational because most of the members for both in-situ and indoor can be shared.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional side view showing a usage state of an in-situ shear test apparatus according to the present invention.

FIG. 2 is a plan view of an in-situ shear test apparatus according to the present invention.

FIG. 3 is a front view of the in-situ shear test apparatus according to the present invention.

FIG. 4 is a vertical sectional side view showing a test state of the in-situ shear test apparatus according to the present invention.

FIG. 5 is a vertical sectional front view showing a test state of the in-situ shear test apparatus according to the present invention.

FIG. 6 is a plan view showing a test state of the in-situ shear test apparatus according to the present invention.

FIG. 7 is a side view of the indoor shear test apparatus according to the present invention.

FIG. 8 is a front view of the indoor shear test apparatus according to the present invention.

FIG. 9 is a diagram showing one test result according to the present invention.

FIG. 10 is a diagram showing another test result according to the present invention.

FIG. 11 is a diagram showing another test result according to the present invention.

FIG. 12 is a diagram showing another test result according to the present invention.

[Explanation of symbols]

 1 Base 2 Opening 3 Storage Holding Frame 4 Slide Guide 5 Fixed Wall 6 Horizontal Pressing Device 7 Pushing Rod 8 Pushing Force Measuring Device 9 Support Guide 10 Pushing Rod 11 Horizontal Displacement Meter 12 Loading Plate 13 Thrust Bearing 14 Vertical Pushing Device 15 Pushing Actuating rod 16 Pressing force measuring instrument 17 Vertical pressurizing device 18 Supporting material 19 Vertical displacement meter 20 Stopper 21 Reaction force support 22 Base 23 Support leg 24 Soil sample receiving box 25 Horizontal material 26 Strut 27 Reaction force support S Soil sample

Claims (4)

[Claims] 1. A base 1 provided with an opening 2 through which the soil sample S passes.
And a storage and holding frame 3 formed in a frame shape for storing and holding the soil sample S protruding upward from the opening 2 and slidably installed along a slide guide 4 provided on the base 1.
And a lateral pressing device 6 fixed to the rear base 1 in the sliding direction of the storage holding frame 3 and projecting a pressing operation rod 7 toward the rear end surface of the storage holding frame 3, and a tip of the pressing operation rod 7. The pressing force measuring device 8 attached with a pressing rod at the tip in the measuring direction, the horizontal displacement gauge 11 installed on the base 1 in the sliding direction front of the storing and holding frame 3, and the storing and holding frame 3 are stored. Loading plate 12 placed on the soil sample S
And a vertical pressing force device 14 installed on the loading plate 12 via a thrust bearing 13 with the pressing operation rod 15 facing vertically upward, and attached to the tip of the pressing operation rod 15 via a pressing force measuring device 16. A vertical pressurizing device 17 that applies a downward pressing force vertically, and a vertical displacement gauge 19 for measuring the vertical displacement of the vertical pressing device 14 or the loading plate 12.
An equal volume shear test device comprising: 2. A base 1 provided with an opening 2 through which the soil sample S passes.
And a storage and holding frame 3 formed in a frame shape for storing and holding the soil sample S protruding upward from the opening 2 and slidably installed along a slide guide 4 provided on the base 1.
And a lateral pressing device 6 fixed to the rear base 1 in the sliding direction of the storage holding frame 3 and projecting a pressing operation rod 7 toward the rear end surface of the storage holding frame 3, and a tip of the pressing operation rod 7. The pressing force measuring device 8 attached with a pressing rod at the tip in the measuring direction, the horizontal displacement gauge 11 installed on the base 1 in the sliding direction front of the storing and holding frame 3, and the storing and holding frame 3 are stored. Loading plate 12 placed on the soil sample S
And a vertical pressing force device 14 installed on the loading plate 12 via a thrust bearing 13 with the pressing operation rod 15 facing vertically upward, and attached to the tip of the pressing operation rod 15 via a pressing force measuring device 16. A vertical pressurizing device 17 that applies a downward pressing force vertically, and a vertical displacement gauge 19 for measuring the vertical displacement of the vertical pressing device 14 or the loading plate 12.
And a stopper 20 provided at a position where the portion of the pressing device 14 on the front side in the sliding direction of the storage holding frame 3 can be locked.
An equal volume shear test device comprising: 3. A base 1 provided with an opening 2 through which the soil sample S passes.
And a storage and holding frame 3 formed in a frame shape for storing and holding the soil sample S protruding upward from the opening 2 and slidably installed along a slide guide 4 provided on the base 1.
And a lateral pressing device 6 fixed to the rear base 1 in the sliding direction of the storage holding frame 3 and projecting a pressing operation rod 7 toward the rear end surface of the storage holding frame 3, and a tip of the pressing operation rod 7. The pressing force measuring device 8 attached with a pressing rod at the tip in the measuring direction, the horizontal displacement gauge 11 installed on the base 1 in the sliding direction front of the storing and holding frame 3, and the storing and holding frame 3 are stored. Loading plate 12 placed on the soil sample S
And a vertical pressing force device 14 installed on the loading plate 12 via a thrust bearing 13 with the pressing operation rod 15 facing vertically upward, and attached to the tip of the pressing operation rod 15 via a pressing force measuring device 16. A vertical pressurizing device 17 that applies a downward pressing force vertically, and a vertical displacement gauge 19 for measuring the vertical displacement of the vertical pressing device 14 or the loading plate 12.
And a reaction force support installed at the upper end of the pressurizing device 17, an equal volume shear test device. 4. A base 1 provided with an opening 2 through which the soil sample S passes.
And a storage and holding frame 3 formed in a frame shape for storing and holding the soil sample S protruding upward from the opening 2 and slidably installed along a slide guide 4 provided on the base 1.
And a lateral pressing device 6 fixed to the rear base 1 in the sliding direction of the storage holding frame 3 and projecting a pressing operation rod 7 toward the rear end surface of the storage holding frame 3, and a tip of the pressing operation rod 7. The pressing force measuring device 8 attached with a pressing rod at the tip in the measuring direction, the horizontal displacement gauge 11 installed on the base 1 in the sliding direction front of the storing and holding frame 3, and the storing and holding frame 3 are stored. Loading plate 12 placed on the soil sample S
And a vertical pressing force device 14 installed on the loading plate 12 via a thrust bearing 13 with the pressing operation rod 15 facing vertically upward, and attached to the tip of the pressing operation rod 15 via a pressing force measuring device 16. A vertical pressurizing device 17 that applies a downward pressing force vertically, and a vertical displacement gauge 19 for measuring the vertical displacement of the vertical pressing device 14 or the loading plate 12.
And a reaction force support installed at the upper end of the pressurizing device 17, and a soil sample receiving box installed immediately below the storage holding frame 3 and forming a series of soil sample storage spaces with the storage holding frame 3 through the opening 2. 24. An equal volume shear test device comprising 24.