KR100764243B1 - Consolidation cell with horizontal drain and measuring elastic wave and apparatus for testing consolidation characteristics therewith - Google Patents

Abstract

A horizontal drain consolidation cell for measuring elastic waves and a consolidation testing system using the same are provided to test horizontal consolidation characteristics according to a vertical load and to measure shearing wave speed simultaneously by adhering a transducer at a consolidation ring. A horizontal drain consolidation cell for measuring elastic waves comprises a lower plate(430), a upper plate cover(410), a porous consolidation ring(420), and a support. The lower plate receives a sample while preventing permeation of the moisture of the sample. The upper plate cover is mounted to cover the sample while preventing permeation of the moisture of the sample. The consolidation ring is positioned between the upper plate cover and the lower plate to seal the space containing the sample, and formed of a porous plate to drain the moisture of the sample. An engraved scale is formed on the surface of the porous consolidation ring, contacted with the sample, to measure a lowering degree of the upper plate cover. The support fixes the porous consolidation ring to the lower plate.

Description

Consolidation cell with horizontal drain and measuring elastic wave and Apparatus for testing consolidation characteristics therewith}

1 illustrates a vertical drainage environment.

FIG. 2 illustrates a consolidation promoting method using a vertical drainage material in the environment of FIG. 1.

3 illustrates a compaction cell used in a conventional compaction test.

4 is a perspective view of a consolidation cell for horizontal drainage according to the present invention.

5 is a side view of FIG. 4.

6 is a top view of FIG. 4.

7 is a structural diagram of a consolidation test apparatus using a consolidation cell for transverse drainage according to the present invention.

The present invention relates to a consolidation test, and more particularly, to a consolidation test apparatus using a condensation cell for horizontal drainage and a consolidation cell for transverse drainage.

When constructing structures in the field of civil engineering, especially in geotechnical engineering, structures are often placed on soft ground. In this case, soft ground mainly refers to cohesive soil, and if the structure is constructed directly on the ground, overlying or floating settlement that exceeds the allowable settlement in the long term will have an adverse effect on the structure and eventually cause the structure to collapse. Let's go. Therefore, in order to construct a structure on such ground, improvement of the ground must be preceded first.

All soils are compressible. That is, the volume decreases when the soil is loaded. At this time, the three elements constituting the soil, that is, soil particles and water among the soil particles, water, and air are incompressible, so the volume reduction of the soil results in compressing or dissolving the air occupying the gap between the soil particles. This is because the water escapes from the. If the soil is completely saturated, compression occurs due to the escape of fluid water. At this time, the compression speed depends on the speed of the water flowing out of the gap, and condensation is the phenomenon that the ground is compressed as water escapes from the soil over a long time.

For the improvement of the ground, first, the compressive characteristics of clay soil are investigated through field or indoor experiments. The test conducted in the laboratory is the consolidation test and is one of the most widely conducted tests in the field of geotechnical engineering.

Through the consolidation test, the consolidation constants (compression index, preceding consolidation load, volume compression coefficient, consolidation coefficient) can be obtained. Using this consolidation constant, the sedimentation characteristics (sedimentation rate, settlement rate) generated when the viscous soil is subjected to one-dimensional compaction can be identified.

When constructing a structure such as a road embankment on the soft ground as shown in FIG. 1, it is necessary to estimate the final settlement due to consolidation and the time required for the settlement to occur at a certain rate, for example, 50% or 90%. This calculation is required when determining the height of the fill or the construction period. The consolidation characteristics of the soil are also used for the design of soft ground treatments such as preloading, sand drain or paper drain.

The ground upon which the structure is to be designed must have sufficient capacity to support the structure. In the case of soft ground, it is necessary to improve the supporting capacity and have sufficient stability according to the particle characteristics of the ground or the environmental characteristics.

In the soft ground containing a lot of moisture, civil structures or buildings cannot be stably constructed, so the so-called soft ground improvement works that enhance the strength of the soft ground prior to construction should be preceded. In order to remove the gap water contained in the soft ground, a drain method for keeping the ground tight is used.

According to the drain method, since the drain material absorbs moisture in the surrounding ground and discharges it to the outside, the ground is consolidated and hardened.

As a soft ground improvement method, the consolidation promotion method using the vertical drainage material, the compact soil method, etc., as shown in FIG. 2, promote consolidation to minimize settlement of the structure afterwards and improve the strength performance of the ground. In order to apply the ground improvement method, it is necessary to understand the consolidation characteristics of the soft ground so that economic and efficient design can be performed.

While the consolidation promotion methods shorten the drainage distance and promote consolidation through the lateral consolidation characteristics, the laboratory tests to grasp the consolidation characteristics of the conventional ground, as shown in Figure 3, the vertical direction through the vertical drainage for vertical load The method of analyzing the consolidation characteristics for is common.

However, the conventional consolidation cell does not adequately reflect the characteristics that the horizontal drainage is superior to the vertical drainage in the consolidation test environment, there is a problem that can be consistent with the conservative design from the results of the test.

The first technical problem to be achieved by the present invention is to provide a condensation cell for lateral drainage that can properly reflect the characteristics that the horizontal drainage is superior to the vertical drainage in the consolidation test, and can grasp the lateral consolidation characteristics according to the vertical load.

The second technical problem to be achieved by the present invention is to properly reflect the characteristics that the horizontal drainage is superior to the vertical drainage in the consolidation test, it is possible to grasp the transverse consolidation characteristics according to the vertical loading load, the shear wave velocity according to the transverse consolidation behavior It is to provide a consolidation cell for transverse drainage in parallel to measure the seismic wave can be measured together.

The third technical problem to be achieved by the present invention is to provide a consolidation test apparatus using a transverse consolidation cell capable of performing a consolidation test, including the consolidation cell for transverse drainage.

In order to achieve the first technical problem, the present invention can contain a sample, the lower plate which is not permeable to the water of the sample, the top cover to cover the sample, the water cover of the sample is not permeable, the top cover and the lower plate Placed in the lateral direction between the sealed the space in which the sample is contained, consisting of a porous plate to drain the moisture contained in the sample and through the porous consolidation to fix the porous consolidation to the lower plate It provides a consolidation cell for transverse drainage including a support to make.

In order to achieve the second technical problem, the present invention can contain a sample, the lower plate which is not water-permeable of the sample, the top cover that covers the sample, the water is not water-permeable of the sample, the top plate and the lower plate It is disposed in the lateral direction between the sealed the space in which the sample is contained, porous consolidation ring to drain the water contained in the sample, consisting of a porous plate, penetrates between the outside and the inside of the porous consolidation ring, facing each other Consolidation cell for transverse drainage in parallel with the elastic wave measurement comprising a plurality of transducers disposed in the form and measuring the speed of the elastic wave passing through the sample and a support for fixing the porous consolidation ring to the lower plate through the porous consolidation ring to provide.

In order to achieve the third technical problem, the present invention can contain a sample, the lower plate which is not water-permeable of the sample, the upper plate cover that covers the sample, the water is not water-permeable of the sample, the top plate cover is set in advance Loading bar pressed by pressure, disposed between the top plate and the lower plate in the lateral direction to seal the space in which the sample is contained, porous consolidation ring consisting of a porous plate to drain the water contained in the sample, the porous consolidation ring It provides a consolidation test apparatus using a transversal consolidation cell comprising a support for fixing the porous consolidation ring to the lower plate and a distance measuring unit for measuring the distance between the lower plate and the upper cover.

An object of the present invention is to determine the transverse consolidation characteristics that can be applied to the ground improvement design, and to develop equipment that can determine the characteristics of the sample by measuring the seismic velocity in parallel with the transverse consolidation test. In addition, the consolidation test and the seismic measurement test can be performed in parallel, and the transverse consolidation test and the seismic measurement test can be performed simultaneously by allowing the lateral drainage of the consolidation cell that can be tested by minimizing the sample disturbance.

The present invention includes a porous consolidation ring capable of lateral drainage, and arranges an elastic wave measurable transducer according to the effective stress in the porous consolidation ring, and the transducer is provided in the porous consolidation ring. It is fixed in the socket for the installed transducer. Preferably, the transducer and the socket for the transducer can be combined with a rubber O-ring to prevent direct contact of the waterproof and metal insert with the test apparatus.

Preferably, the porous consolidation may be made to a UD sample size that minimizes sample disturbances. UD sample means a sample collected at a constant size for the consolidation test.

Consolidation is the removal of water and air from the gaps in the soil. On the other hand, compaction differs from consolidation in that only air in the gap is removed. All soils are compressible. That is, sinking occurs when a load is applied. When pressure is applied to the soil, an immediate settlement occurs and a primary consolidation settlement occurs, which reduces the volume of the soil. After primary consolidation, secondary consolidation settlement occurs due to plastic alignment of soil structure. It is a function that depends on the time of the second consolidation, whereas the primary consolidation is determined by the exit of the water and air from the gap. Therefore, the second consolidation takes a long time.

The basic principle of consolidation is that when the saturated soil layer receives additional stress, the pore water pressure in the soil increases by the additional stress. This is called excess pore water pressure. In addition, dissipation of excess pore water pressure occurs. Since clay has a smaller permeability coefficient than sandy soils, dissipation of pore water gradually dissipates over a long period of time. When the pore water dissipates, the effective stress increases in the soil at any depth, and a second consolidation settlement occurs under this constant effective stress.

와 같으며, 이에 따라 배수거리를 짧게 하면 연약지반의 압밀침하 시간을 단축할 수 있다는 것을 알 수 있으며, 드레인재의 특성에 따라서도 압밀침하 시간이 크게 달라지게 된다.On the other hand, according to Terzaghi's first consolidation theory, the relationship between the time (t) and the maximum drainage distance (H) required to consolidate the soft ground is

As such, if the drainage distance is shortened, it can be seen that the consolidation settlement time of the soft ground can be shortened, and the consolidation settlement time greatly varies depending on the characteristics of the drain material.

The seismic detection method is an exploration method that measures the propagation speed of an acoustic wave due to the difference in elasticity of rocks and minerals and analyzes it.

When an external force is applied to the object, the object is deformed. When the external force is removed, the property of returning to the original state is called elasticity of the material. Elasticity is used to obtain underground information because of the difference in transmission speed depending on the object (type of rock). Since the force acting on a unit area is called stress, Hook's law that elastic strain reflects stress is called elastic material.

When an object is impacted, its wavelength is transmitted to the object, which is called a seismic wave. Acoustic waves are classified into longitudinal waves, shear waves, and surface waves. The longitudinal wave is called the fastest P wave (prinary wave) among the seismic waves, and the propagation speed is shown in Equation 1 below.

Where R is the volume elastic flow, ρ is the density, and μ is the stiffness.

Shear waves are called S wave (secondary wave) and the propagation speed is given by the elastic modulus of the medium. The propagation speed of the S wave is shown in Equation 2 below.

Surface waves propagate with energy concentrated on a surface or interface and are divided into Rayleigh waves and love waves. The velocity of seismic wave propagation in rock depends on the quality of the rock.

Acoustic waves are refracted when they reach the interface of strata with different propagation velocities and densities, which represent qualitative differences in rock.

The seismic wave can be calculated by measuring the time taken for the seismic wave to reach by using a wave oscillator or transducer installed in the ground or on the ground. The seismic segregation is clear at 3.5-5.5 km / sec in granite, while the seismic velocity in clay and sand is 0.5-1.5 km / sec.

Hereinafter, with reference to the drawings will be described a preferred embodiment of the present invention. However, embodiments of the present invention illustrated below may be modified in many different forms, and the scope of the present invention is not limited to the embodiments described below.

4 is a perspective view of a consolidation cell for horizontal drainage according to the present invention.

The top cover 410 covers the sample and is made of a material that does not penetrate the sample.

Porous consolidation ring 420 is disposed in the lateral direction between the upper plate cover 410 and the lower plate 430 to seal the space containing the sample, consisting of a porous plate made of a material that can drain the moisture contained in the sample do. Preferably, the porous consolidation ring 420 may be made of a predetermined porous metal. Preferably, the porous consolidation ring 420 may be configured to measure the degree of falling of the top cover 410 including a graduation engraved intaglio on the inner surface in contact with the sample.

The lower plate 430 may contain a sample, and is made of a material that does not penetrate the moisture of the sample.

Preferably, the upper cover 410 and the lower plate 430 may be manufactured by molding a brass plate.

Consolidation cell for transverse drainage in parallel with the measurement of the acoustic wave according to the present invention includes an upper plate cover 410, a porous consolidation ring 420, a lower plate 430, a plurality of transducers (451-453).

The top cover 410 covers the sample and is made of a material that does not penetrate the sample. Preferably, the top cover 410 may be manufactured by molding a brass plate.

Porous consolidation ring 420 is disposed in the lateral direction between the upper plate cover 410 and the lower plate 430 to seal the space containing the sample, consisting of a porous plate made of a material that can drain the moisture contained in the sample do. Preferably, the porous consolidation ring 420 may be made of a predetermined porous metal.

Preferably, the porous consolidation ring 420 may be configured to measure the degree of falling of the top cover 410 including a graduation engraved intaglio on the inner surface in contact with the sample.

The lower plate 430 may contain a sample, and is made of a material that does not penetrate the moisture of the sample. Preferably, the lower plate 430 may be manufactured by molding a brass plate.

The plurality of transducers 451-453 penetrate between the outer and inner sides of the porous consolidation ring 420 and face each other to measure the speed of the acoustic wave passing through the sample.

At this time, any one of the opposing transducers propagate the input wave (elastic wave) to the sample, the other transducer receives the acoustic wave passing through the sample. Preferably, the transducers 451-453 are coupled with a rubber O-ring to a socket for a transducer installed in the porous consolidation ring, and either side of the transducer contacts the sample, The other side can be connected to a circuit for measuring acoustic waves.

In this case, the circuit for measuring the acoustic wave may include a signal generator (not shown) for generating a predetermined input wave, that is, an elastic wave, and an elastic wave speed measuring unit (not shown) for receiving the elastic wave passing through the sample and measuring the speed of the elastic wave. .

5 is a side view of FIG. 4.

The top cover 510 covers the sample and is made of a material that does not penetrate the sample. Preferably, the top cover 510 may be manufactured by molding a brass plate.

The porous consolidation ring 520 is disposed in the lateral direction between the upper plate cover 510 and the lower plate 530 to seal the space in which the sample is contained, and is composed of a porous plate and is made of a material capable of draining moisture contained in the sample. do. Preferably, the porous consolidation ring 520 may be made of a predetermined porous metal.

Preferably, the porous consolidation ring 520 may be configured to measure the degree of falling of the top cover 510 including a graduation engraved intaglio on the inner surface in contact with the sample.

At this time, when the upper cover 510 is lowered, or when the sample is subjected to pressure in such a way that the lower plate 530 is lifted, the moisture contained in the sample is released, wherein the drainage direction is the side direction as shown in FIG. do.

The lower plate 530 may contain a sample and is made of a material that does not penetrate the moisture of the sample. Preferably, the lower plate 530 may be manufactured by molding a brass plate.

6 is a top view of FIG. 4.

The porous consolidation ring 620 is disposed in the lateral direction between the upper plate cover 610 and the lower plate 630 to seal the space in which the sample is contained, and is composed of a porous plate to be made of a material capable of draining the water contained in the sample. do. Preferably, the porous consolidation ring 620 may be made of a predetermined porous metal.

Preferably, the porous consolidation ring 620 may be configured to measure the degree of falling of the top cover 610, including a graduation engraved intaglio on the inner surface in contact with the sample.

The plurality of transducers 650 penetrate between the outer and inner sides of the porous consolidation ring 620 and face each other to measure the velocity of the acoustic wave passing through the sample.

At this time, any one of the opposing transducers propagate the input wave (elastic wave) to the sample, the other transducer receives the acoustic wave passing through the sample. Preferably, the transducer 650 is coupled with a rubber O-ring to a socket for a transducer installed in the porous consolidation ring, either side of the transducer being in contact with the sample and the other end of the transducer. The side can be connected to a circuit for measuring acoustic waves.

Preferably, the transverse consolidation cell according to the present invention may further include a support (circular black portion) for penetrating the porous consolidation ring 620 to fix the porous consolidation ring 620 to the lower plate.

7 is a structural diagram of a consolidation test apparatus using a consolidation cell for transverse drainage according to the present invention.

The top cover 710 covers the sample and is made of a material that does not penetrate the moisture of the sample. Preferably, the top cover 710 may be manufactured by molding a brass plate.

The porous consolidation ring 720 is disposed in the lateral direction between the upper cover 710 and the lower plate 730 to seal the space in which the sample is contained, and is composed of a material that can drain the moisture contained in the sample by the porous plate. do. Preferably, the porous compacting ring 720 may be made of a predetermined porous metal.

Preferably, the porous consolidation ring 720 may be configured to measure the degree of falling of the top cover 710, including a graduation engraved intaglio on the inner surface in contact with the sample.

The lower plate 730 may contain a sample, and is made of a material that does not penetrate the moisture of the sample. Preferably, the lower plate 730 may be manufactured by molding a brass plate.

The loading bar 740 presses the top cover to a predetermined pressure. In this case, the preset pressure may be set by attaching the weight 741 as shown in FIG. 7, or by setting the loading bar 740 to apply downward force through another pressure applying means.

Preferably, the consolidation test apparatus using a transverse consolidation cell according to the present invention is a support for fixing the porous consolidation ring 720 to the lower plate 730 or the ground through the porous consolidation ring 720 (circular in Figure 6 Black portion).

The distance measuring unit 760 measures the distance between the lower plate and the upper plate cover, as shown in FIG. 7, a method of displaying a ruler, a method of displaying a gauge scale, and electronically detecting a position of the loading bar 740 with a sensor. It can be a way to.

Preferably, the consolidation test apparatus using the transverse consolidation cell according to the present invention includes a pressure sensor for measuring the pressure exerted by the loading bar 740, a means for measuring the amount of displacement of the loading bar 740 per hour, thus measuring It can be configured as a system that can analyze the pressure and the displacement amount per hour by computer to determine the consolidation characteristics.

In order to analyze the consolidation characteristics using the consolidation test apparatus using the condensation cell for transverse drainage according to the present invention, first, pressurized water may be added to a housing made of a porous consolidation ring 720 and a lower plate 730. The reason for pressurizing the pressurized water is to remove air by dissolving the fine air bubbles contained in the sample with the pressurized water. When the load is applied to the loading bar 740, the sample is compressed and the water contained in the sample is drained through the porous consolidation ring 720. When a load is applied while pressing the loading bar 740 at a constant speed, a deformation of the sample occurs at a constant speed. At this time, the stress of the upper part of the sample, the pore water pressure and the displacement of the lower part, etc. may be measured and analyzed.

Although the present invention has been described with reference to one embodiment shown in the drawings, this is merely exemplary and will be understood by those of ordinary skill in the art that various modifications and variations can be made therefrom. However, such modifications should be considered to be within the technical protection scope of the present invention. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

As described above, according to the present invention, by using the consolidation ring capable of lateral drainage, it is possible to appropriately reflect the characteristic that the horizontal drainage is superior to the vertical drainage in the consolidation test, and grasp the transverse consolidation characteristics according to the vertical loading load. It is possible, and by attaching the transducer for measuring the acoustic wave to the consolidation ring, there is an effect that can measure the shear wave velocity according to the transverse consolidation behavior.

Claims (13)

A lower plate which can hold a sample and is not permeable to moisture of the sample; A top cover covering the sample and not allowing water of the sample to pass through; It is arranged in the lateral direction between the upper plate and the lower plate to seal the space in which the sample is contained, consisting of a porous plate to drain the moisture contained in the sample, is made of UD sample size to minimize sample disturbance, A porous consolidation ring engraved with an intaglio scale capable of measuring the degree of falling of the top cover on the surface in contact with the sample; And Consolidation cell for horizontal drainage comprising a support for penetrating the porous consolidation ring to fix the porous consolidation ring to the lower plate. The method of claim 1, The porous consolidation is Consolidation cell for horizontal drainage, characterized in that made of a predetermined porous metal. The method of claim 1, The top cover is Consolidation cell for horizontal drainage, characterized in that is manufactured by molding a brass plate. delete delete A lower plate which can hold a sample and is not permeable to moisture of the sample; A top cover covering the sample and not allowing water of the sample to pass through; A porous consolidation ring disposed in the lateral direction between the upper plate cover and the lower plate to seal the space in which the sample is contained and to drain the water contained in the sample by a porous plate; A plurality of transducers penetrating between an outer side and an inner side of the porous consolidation ring and facing each other to measure a velocity of an elastic wave passing through the sample; And Consolidation cell for transverse drainage parallel to the measurement of the acoustic wave including a support for penetrating the porous consolidation ring to secure the porous consolidation ring to the lower plate. The method of claim 6, The porous consolidation is Consolidation cell for transverse drainage in parallel with the measurement of the acoustic wave, characterized in that made of a predetermined porous metal. The method of claim 6, The top cover is Consolidation cell for horizontal drainage parallel to the measurement of the acoustic wave, characterized in that the brass plate is produced by molding. The method of claim 6, The transducer Coupled with a rubber O-ring to the transducer socket installed in the porous consolidation ring, one side of the transducer is in contact with the sample, the other side of the transducer in the circuit for measuring acoustic waves Consolidation cell for transverse drainage parallel to the measurement of the acoustic wave characterized in that the connection. The method of claim 9, The circuit for measuring acoustic waves A signal generator for generating a predetermined input wave; And Consolidation cell for horizontal drainage parallel to the measurement of the acoustic wave, characterized in that it comprises an acoustic wave velocity measuring unit for receiving the input wave passed through the sample to measure the velocity of the elastic wave. The method of claim 6, The transducer Consolidation cell for transverse drainage is fixed to the transducer socket installed in the porous consolidation ring, the transducer and the transducer socket is combined with a rubber O-ring (O-ring). A lower plate which can hold a sample and is not permeable to moisture of the sample; A top cover covering the sample and not allowing water of the sample to pass through; A loading bar for pressing the top cover at a predetermined pressure; Porous consolidation ring formed in the UD sample size disposed in the lateral direction between the upper cover and the lower plate to seal the space containing the sample, consisting of a porous plate to drain the moisture contained in the sample and minimize sample disturbance ; A support for fixing the porous consolidation ring to the lower plate through the porous consolidation ring; And Consolidation test apparatus using a transverse consolidation cell including a distance measuring unit for measuring the distance between the lower plate and the upper cover. delete

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