KR20090093172A - Clamp for accelerated compressive creep test of geosynthetics - Google Patents

Abstract

An acceleration compression creep test clamp of a geosynthetics for the drainage is provided to reduce the error of measurement data by increasing the temperature of a test piece step by step. An acceleration compression creep test clamp of a geosynthetics for the drainage comprises a top and a bottom compression clamp(10,20) and an angle adjusting clamp(30). The angle adjusting clamp is formed between the top and the bottom compression clamp. The angle adjusting clamp grips a test piece(T). The angle adjusting clamp is pivotally installed. The test piece of the geosynthetics for the drainage can be compressed by the angle adjusting clamp according to the various tilt angle(A).

Description

Clamp for accelerated compressive creep test of geosynthetics

The present invention relates to a clamp for use in a device for measuring the acceleration and compression creep characteristics of geosynthetics for drainage used in civil engineering, in particular, geosynthetics for drainage to be able to calculate the exact creep characteristics of geosynthetics Clamps for accelerated compression creep testing of test specimens.

Geosynthetics is a product made from polymer raw materials, used with soil, rock and ground in civil engineering, construction, or other civil engineering technologies. Geotextiles, Geomembranes, Geogrid There are various types of products such as Geogrid, Geocomponent, Geonet, Plastic drain board, Geomat, and GCLs (Geosynthetic Clay Liners).

These geosynthetics are mainly used for leachate or gas spill prevention and slope reinforcement, soft ground reinforcement, retaining wall and slope protection, groundwater or surface water drainage.

Among them, geosynthetics used for drainage reduces the thickness of the product due to long-term compression due to the load of soil, etc., thereby reducing the horizontal transmissivity. The method of evaluating life is specified in the Reliability Standard (RS).

Drainage geosynthetics is considered to have reached the end of their life when excessive creep deformation occurs, resulting in a decrease in thickness due to prolonged compression resulting in a decrease in horizontal transmission. In order to predict the life of the geosynthetics for drainage by creep deformation, or to estimate the thickness of the geosynthetics for drainage during installation to have the required life in the field, a constant load, A stepped isothermal method (SIM), which is a creep test performed by gradually raising the test temperature under stress, is used.

On the other hand, Figure 3 is a view schematically showing a clamp for testing the conventional accelerated compression craft.

In the conventional accelerated compression creep test clamp 100, a stress adding portion (not shown) for applying stress, the upper compression clamp 110 is fixed to the stress adding portion, the lower portion of the upper compression clamp 110 and the upper compression clamp Lower compression clamp slidable to one side through a roller installed on the ground to hold the specimen (T), which is located below and has an upper surface roughly parallel to the lower surface of the upper compression clamp, to prevent deformation of the upper compression clamp due to excessive stress. The chamber 130 includes a 120 and a heating means 131 for adjusting the temperature. In addition, measuring means 140 such as a gauge for measuring the deformation and stress of the test piece is further provided.

In this case, the substantially parallel contact surfaces 111 and 112 of the upper compression clamp and the lower compression clamp may be configured to have a constant inclination for measuring in an environment similar to an inclined surface on which the actual drainage geosynthetics is installed.

By using a conventional clamp 100 having such a configuration, while gradually adding a predetermined stress to the test piece with the stress adding portion, the temperature of the test piece is varied by the heating means 131 in the chamber 130 and the strain of the test piece due to the stress. The creep characteristics are calculated based on the strain.

Since the conventional clamp measures the creep characteristics of the test piece under a predetermined inclination angle condition, it is difficult to consider the load direction according to various inclination angles in which actual geosynthetics is used. That is, the greater the difference between the inclination angle of the contact surface of the conventional upper and lower compression clamps and the inclination angle in which the actual geosynthetics is used, the lower the reliability of the creep characteristics such as the expected life or the required thickness calculated from the measured strain. will be.

In addition, the conventional clamp uses a method in which the temperature in the air in the chamber is raised so that the temperature in the air is transferred to the test piece to meet the test temperature conditions. There is a problem that the time required for the test piece to be increased until the temperature of the test piece increases and the test time increases, and it is difficult to accurately match the temperature conditions of the test piece because of the indirect heating method. For this reason, there exists a problem that the reliability regarding creep characteristics, such as the predicted life expectancy calculated | required from the measurement data obtained in inaccurate temperature conditions, or a required thickness, is inferior.

The present invention has been made to solve the above-mentioned problems, by adjusting the inclination angle of the test piece according to the inclination angle in which the actual geosynthetics is used, to accurately measure the creep characteristics of the test piece by making the direction of the stress equal to the actual use environment This has the purpose of increasing the reliability of the data to be measured.

It also has the purpose of increasing the reliability of the creep characteristics calculated by increasing the temperature of the test piece accurately and stepwise to obtain measurement data with few errors.

As a means for solving the above-described problems, an embodiment of the present invention in the accelerated compression creep test clamp for measuring the accelerated compression creep characteristics of the geosynthetics for drainage, the test piece of the geosynthetics for drainage various inclination angle In order to accelerate the compression according to the conditions, the test piece is gripped between the upper and lower compression clamps, and the present invention provides a clamp for testing the accelerated compression creep of the geosynthetics for drainage, which is provided with a rotatable angle adjustment clamp.

In addition, the angle adjustment clamp provides a clamp for testing the accelerated compression creep of the geosynthetics for drainage, characterized in that the heating unit is further provided for accurately raising the test piece.

According to a preferred embodiment of the present invention, the creep characteristics of the test piece are measured under the same angular conditions as the angle of the slope of which the drainage geosynthetics is used due to the rotatable angle adjusting clamp positioned between the upper and lower compression clamps. This has the effect of increasing reliability in data such as lifespan.

In addition, the heating part provided in the angle adjusting clamp in direct contact with the test piece in the conventional method of heating the air in the chamber can increase the temperature of the test piece more accurately, thereby reducing the error of the test data.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a view schematically showing a state of use of a clamp for accelerated compression creep test of drainage geosynthetics according to an embodiment of the present invention.

Figure 2 is a perspective view of the lower inclination adjustment clamp employed in the clamp for testing the accelerated compression creep of drainage geosynthetics shown in FIG.

Figure 3 is a schematic view showing a clamp for testing the conventional accelerated compression craft.

* Description of the major reference numerals in the drawing *

1: clamp

10: upper compression clamp 20: lower compression clamp

21: roller 30: angle adjustment clamp

31: upper angle adjustment clamp 32: lower angle adjustment clamp

40: heating part 41: power connection member

A: tilt angle

100: clamp 110: upper compression clamp

120: lower compression clamp 111112: contact surface

130: chamber 131: heating means

140: measuring means T: test piece

Hereinafter, with reference to the accompanying drawings will be described the function, configuration and operation of the clamp for testing the accelerated compression creep of drainage geosynthetics according to a preferred embodiment of the present invention.

1 is a view schematically showing a state of use of the clamp for testing the accelerated compression creep of drainage geosynthetics according to an embodiment of the present invention. However, in the drawings, the block arrow indicates the direction of the applied stress, and the solid arrow indicates the direction in which the clamp can be moved or changed.

Accelerated compression creep test clamp 1 of the geosynthetics for drainage according to a preferred embodiment of the present invention is provided with an upper compression clamp 10, the lower compression clamp 20 and the angle adjustment clamp 30.

The upper compression clamp 10 is coupled to the lower portion of the stress adding portion (not shown) that adds stress in the downward direction, and has a function of transferring the stress in the downward direction.

On the other hand, the lower compression clamp 20 is located below the upper compression clamp, it is to move fluidly to one side in order to prevent the bending of the axis connecting the upper compression clamp and the stress portion when the stress is applied in the upper compression clamp It is configured to be. For this purpose, the lower compression clamp 20 may be installed to be slidable on the plurality of rollers 21 connected to the ground or the ground and placed on a horizontal plate.

On the other hand, the angle adjustment clamp 30 is located between the upper compression clamp 10 and the lower compression clamp 20, while transmitting the stress applied to the upper compression clamp to the test piece, it is possible to adjust the direction of the stress transmitted to the test piece. The specimens can be adjusted at various inclination angles.

The angle adjustment clamp 30, which can change the inclination angle, may have a surface roughness such that the test piece does not slip during the test, and no damage is caused to the test piece by the clamp. The conditions for other clamps, including this one, are in accordance with the conditions mentioned in ASTM D 6364.

Angle adjustment clamp 30 for adjusting the inclination angle of the test piece may specifically have the following configuration.

The angle adjustment clamp 30 includes a semi-cylindrical upper angle adjustment clamp 31 gripped on a curved surface formed under the upper compression clamp, and a semi-cylindrical lower angle adjustment clamp 32 gripped on a curved surface formed on the upper compression clamp. It is provided.

At this time, the test piece (T) is gripped by a substantially flat contact surface facing the upper angle adjustment clamp 31 and the lower angle adjustment clamp 32, the laminated shape of the upper angle adjustment clamp and the lower angle adjustment clamp, the test piece is held Becomes approximately cylindrical. Therefore, the angle adjusting clamp 30 gripped by the curved surfaces of the upper and lower compression clamps 10 and 20 may be installed according to the required inclination angle.

This inclination angle (A) is set during the assembly process of placing the lower inclination angle clamp 32 in the lower compression clamp 20, once the lower inclination angle clamp 32 is placed in the lower compression clamp 20 Even when stress is applied to the test piece by friction between the curved surface of the lower compression clamp 20 and the outer circumferential surface of the lower inclination angle clamp 32, the lower angle adjustment clamp 32 does not slide on the curved surface of the lower compression clamp 20. The tilt angle is maintained.

On the other hand, the side of the lower compression clamp 20 and the lower inclination adjustment clamp 32 may be displayed a scale indicating the angle so that the user can easily recognize the inclination angle.

As a result, since the test can be performed under the proper inclination angle in consideration of the stress direction according to the inclination angle in which the drainage geosynthetics is actually used, the reliability of the performance of the drainage geosynthetics calculated from the measurement data is increased.

On the other hand, Figure 2 is a perspective view of the lower inclination adjustment clamp employed in the acceleration compression clamp of the geosynthetics for drainage shown in FIG. However, reference numeral 41 is a power connection member.

In order to increase the temperature of the test piece according to the step isothermal method, the angle adjusting clamp 30 may further include a heating part 40. The heating part 40 may be made of a heating means such as a heating wire using electrical energy provided in the upper and lower angle adjusting clamps to gradually raise the clamp and the test piece. The temperature sensor and the power supply may be used to control the heating means. Conventional control means (not shown), such as a shield, may further be included.

In the test of drainage geosentics by actual step isothermal method, the compression creep strain is sensitive to temperature change, and therefore, it is required to keep the test temperature within ± 2 ° C during the step-up. Since the heating part 40 is provided in the angle adjustment clamp 30 and can raise the temperature of the angle adjustment clamp 30 directly in contact with the test piece T finely, the strain data obtained from the accurately heated test piece is more accurate. Has the effect of being accurate.

Thus, the creep characteristics of the drainage geosynthetics obtained using the accelerated compression creep test clamp (1) of the drainage geosynthetics have a precise load distribution of soil and the like according to the inclination angle of the actual slope. Since it is obtained from the strain data of the test piece under temperature conditions, it will have an effect that reliability increases compared with the conventional thing.

Claims (3)

In the accelerated compression creep test clamp for measuring the accelerated compression creep characteristics of the geosynthetics for drainage, Between the upper and lower compression clamps (10, 20) to accelerate the compression of the test piece (T) of the geosynthetics for drainage according to various inclination angle (A) conditions, The test piece (T) is gripped and the clamp for accelerated compression creep test of drainage geosynthetics, characterized in that the rotatable angle adjustment clamp 30 is provided. In claim 1, The angle adjustment clamp 30 is composed of a semi-cylindrical upper angle adjustment clamp 31 fitted to the upper compression clamp 10, and a semi-cylindrical lower angle adjustment clamp 32 fitted to the lower compression clamp 20. Clamp for accelerated compression creep testing of geosynthetics for drainage. The method of claim 1 or 2, The angle adjustment clamp 30 is a clamp for accelerated compression creep test of drainage geosynthetics, characterized in that the heating unit 40 is further provided for accurate temperature rise of the test piece (T).