JPH0718818B2 - Method of judging degree of compaction of compaction member - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for determining the degree of compaction of compacting members such as embankment material, roadbed material, roadbed material, asphalt pavement material, and crushed stone material. The water content of the compaction member is measured by nondestructive inspection, and the compaction degree is determined from the result.

(Prior Art) Compaction management of artificially compacted structures such as embankments, fill dams, and earth dams is very important for construction management.

Conventionally, these compactions have been performed by the compaction method suitable for the selected compaction member, and the degree of compaction cannot be judged from the appearance, so the sand replacement method, RI (radioisotope)
Method, CBR (california bearing ratio) method, etc.

The sand replacement method is a method of replacing the volume of a hole drilled in the ground with sand and indirectly measuring the volume of soil to determine the density of the ground.

In addition, the RI method is a judgment method that utilizes the principle that the rate of absorption in the soil particles when the gamma rays penetrate the soil has a certain relationship with the soil density.

Furthermore, the CBR method is a method for judging the compaction degree of soil by dividing the load when a piercing rod with a diameter of 5 cm penetrates 0.25 cm by 1,370 kg and expressing it as a percentage.

However, all of the above determination methods not only require a lot of time and effort, but also cannot obtain a large number of determination points, and the determination method is discontinuous, so that the entire determination can be made uniformly and accurately. There was a problem that it could not be done.

Therefore, in order to solve these problems, the actual exploitation 63-13
The invention of 8241 was developed.

This is to measure the change due to the compaction of the bulk material by reflecting the electromagnetic wave emitted from the upper surface of the bulk material by laying it on the base material and compacting it and receiving the reflected electromagnetic wave. Then, the degree of compaction of the loose substance is determined.

(Problems to be Solved by the Invention) However, the determination method as described above requires not only a clear boundary surface to determine the degree of compaction using reflected waves, but also the propagation path length of radio waves I have to understand. That is, since the compaction layer thickness at the determination location must be determined by a separate method, double labor and time are required.

The present invention has been made in view of the above problems, and an object thereof is a clear boundary surface for determining the compaction degree of a compaction member and a compaction degree of a compaction member that does not require a separate determination method. A determination method is provided.

(Means for Solving the Problem) A method for determining the degree of compaction of a compacting member of the present invention for achieving the above object is a transmitter in which a dipole antenna for transmitting an electromagnetic wave is covered with a shield cover, and A receiver whose receiving dipole antenna is covered with a shield cover, and a controller which controls these transmitter and receiver,
A measuring device is constituted by a display device which displays a signal from the receiver, and the transmitter and the receiver in the measuring device are respectively installed on the surface of the compacting member at appropriate intervals and at a predetermined interval from the transmitter. While transmitting electromagnetic waves into the compaction member, the receiver receives surface propagation waves that pass through the surface layer of the compaction member in these electromagnetic waves, and measures the water content of the compaction member by attenuating the received surface propagation waves. However, based on the data of the water content and the degree of compaction set in advance, the configuration is characterized in that the degree of compaction is determined from the measurement result of the water content, and the transmitter and the receiver are appropriately spaced. The electromagnetic wave is emitted from the transmitter into the compacting member at a predetermined interval while moving on the surface of the compacting member in the state of having the above.

(Operation) Therefore, according to the above determination method, the transmitter and the receiver are respectively installed on the upper surface of the compacted compacting member.

Then, the electromagnetic waves emitted from the transmitter at a predetermined interval are
It is received by the receiver as a surface propagating wave propagating through the surface layer of the compacting member.

The surface propagating wave received by the receiver is attenuated by moisture and air in the compacting member when propagating through the surface layer of the compacting member. Therefore, the voltage or propagation time of the attenuated surface propagating wave is measured. To measure the water content of the compaction member.

On the other hand, the density of the compaction member has a specific gravity value and is expressed as a function of the water content and the saturation, so that the relationship between the water content and the density can be set in advance using the saturation as a parameter.

Therefore, the compaction degree of the compaction member can be easily determined from the measurement result of the water content based on this relationship.

Also, by covering the dipole antenna of the transmitter and the dipole antenna of the receiver with a shield cover, it is possible to prevent electromagnetic waves from being transmitted only forward and not leaking to the back side, and at the receiver. Receives only the electromagnetic waves emitted from the vessel.

Further, by moving the compaction member on the surface of the traveling carriage equipped with the transmitter and the receiver, it is possible to increase the number of times of measurement and perform measurement at an arbitrary survey position.

Furthermore, since surface electroplating is used, measurement is possible without a clear layer boundary.

(Embodiment) An embodiment of the method for determining the degree of compaction of the compacting member of the present invention will be described below with reference to the drawings.

Figure 2 shows a voltage of 50Vpp and a frequency of 1GHz, 17cm x 1
It is a plot of the voltage value and the water content of the surface propagating wave that the electromagnetic wave propagates through the sand sample and is received when the 4 cm transmitting and receiving antennas are set at 35 cm intervals. According to this, it is clear that the surface propagation waves tend to be attenuated and become smaller as the amount of water increases in the process from air-drying to saturation.

Therefore, the method for determining the degree of compaction of the compaction member of the present invention utilizes that the surface propagation wave is attenuated in proportion to the water content,
The water content in the compacted compacting member is determined, and the density of the compacting member is calculated based on the moisture content to determine the compaction degree. The measuring device A as shown in FIG. Determined by

The measuring apparatus A is composed of a transmitter 1, a receiver 2, a controller 3 for controlling the transmitter 1 and the receiver 2, and a display 4 for displaying a signal from the transmitter 1.

The oscillator 1 includes a pulsar 5 that generates a pulsed electric power having a very short pulse width of, for example, 1 nsec, a dipole antenna 6a that emits a pulsed electromagnetic wave by the pulsed electric power output from the pulsar 5, and a dipole. Antenna 6a
It is composed of a balun 5a for giving pulsed electric power to the antenna, and a shield cover 7a for shielding the back side of the dipole antenna 6a and shielding electromagnetic waves from leaking to the back side of the dipole antenna 6a.

The receiver 2 is composed of a dipole antenna 6b, a balun 5b, a shield cover 7b, a high frequency amplifier 8 and a gain control circuit 9 for controlling the gain of the high frequency amplifier 8 as described above. A controller 3 is connected to the transmitter 1 and the receiver 2 to send and receive signals and send the received signals to the display 4.

The shield cover 7a attached to the rear surface of the dipole antenna 6a of the transmitter 1 shields the electromagnetic wave emitted from the dipole antenna 6a from only the front side so as not to leak to the rear side and propagates in the air to the receiver 2 It is made for the purpose of preventing the propagation of electromagnetic waves. Therefore, ferrite is used as the material because it can provide a higher shielding effect.

The dipole antenna 6b on the receiver 2 side is also covered with a shield cover 7b.

This shield cover 7b is intended to shield the rear side of the dipole antenna 6a so that the dipole antenna 6a receives only the electromagnetic wave emitted from the transmitter 1.
Like the oscillator 1, a ferrite shield cover 7b is used.

The high frequency amplifier 8 provided in the receiver 2 is a gain control circuit 9
The gain is controlled in synchronization with the transmission cycle of electromagnetic waves.

The received signal amplified by the high frequency amplifier 8 is received by the display device 4 through the controller 3 and displayed.

Next, a method of determining the water content of the compacted compacting member m using the measuring device A will be described.

The compaction member m is embankment material, roadbed material, roadbed material, asphalt pavement material, crushed stone material, etc.
It shall be compacted using m1.

Then, using this embankment material m1, a tamping test or the like is performed in advance to set a control value. That is, the relationship between the water content and the density and compaction degree is set.

In the actual construction, as shown in Fig. 1, the transmitter 1
And receiver 2 are installed on the surface of the compacted embankment material m1.

The distance between the transmitter 1 and the receiver 2 is appropriately set within the range of 25 cm to 2 m according to the frequency used (350 MHz to 1 GHz) and the depth to be measured, and the propagation path length of the surface propagation wave is thereby set. Can be decided

Then, at the same time as transmitting pulsed electromagnetic waves from the transmitter 1 into the compacted embankment material m1, the receiver 2 is activated so that surface propagation waves propagating in the surface layer portion of the embankment material m1 of the electromagnetic waves can be received. First, the high frequency amplifier 8 is controlled so as to have a gain.

The surface propagation wave propagating through the surface layer of the embankment material m1 is received by the receiver 2 in a state of being attenuated in proportion to the amount of water contained in the embankment material m1 and displayed on the display device 4 through the controller 3. It

Then, the voltage of the surface propagating wave is set to be the same as the embankment material shown in FIG.
The water content is judged and displayed by a graph showing the voltage value of the surface propagation wave against the volume water content of m1.

Then, the compaction degree is determined from the measurement results of these water contents based on the preset data of the moisture content and the compaction degree.

(Effects of the Invention) The present invention has the following effects by having the above-mentioned configuration.

Since non-destructive and automatic determination is possible, it is possible to make a wide range of determination, and it is also possible to grasp overall density variations and to perform rational compaction management.

Since the degree of compaction of the compaction member is determined by a non-destructive method, the degree of compaction can be determined without damaging the structure.

By using surface electroplating of electromagnetic waves, it is possible to measure the water content even without a clear layer boundary surface of the compaction member, and by appropriately setting the interval between the transmitter and the receiver, The water content at the desired depth can be measured.

By covering the dipole antenna of the transmitter and the dipole antenna of the receiver with a shield cover,
It is possible to prevent the electromagnetic wave from being emitted only forward and not leak to the back side, and the receiver can receive only the electromagnetic wave emitted from the transmitter.

[Brief description of drawings]

FIG. 1 is a block diagram showing a usage state of the moisture content measuring apparatus of the present invention, and FIG. 2 is a plot diagram showing values of surface propagation waves with respect to volumetric water content of sand. A: Measuring device, 1: Transmitter 2: Receiver, 3: Controller 4: Display, m: Compaction member m1: Fill material

 ─────────────────────────────────────────────────── --- Continuation of the front page (72) Inventor Toru Taniguchi 1-1-20 Minami-Kamata, Ota-ku, Tokyo (72) Inventor Masahiro Nakagawa 1-1-13-6 Shibanishi, Kawaguchi City, Saitama Prefecture (56) References Flat 2-52243 (JP, A) JP-A-63-138243 (JP, A)

Claims (2)

[Claims] 1. A transmitter in which a dipole antenna for transmitting electromagnetic waves is covered with a shield cover, a receiver in which the dipole antenna for receiving the electromagnetic waves is covered with a shield cover, and a controller for controlling these transmitters and receivers. And a display device for displaying a signal from the receiver, which constitutes a measuring device, and the transmitter and the receiver in the measuring device are respectively installed on the surface of the compacting member at an appropriate interval so that a predetermined distance from the transmitter is obtained. The electromagnetic waves are transmitted to the compaction member at intervals, and the surface propagation waves of the electromagnetic waves that pass through the surface layer of the compaction member are received by the receiver, and the water content of the compaction member is reduced by the attenuation of the received surface propagation waves. The compaction degree of the compaction member is characterized by determining the compaction degree from the measurement result of the water content based on the data of the preset water content and the compaction degree. Because the degree of determination method. 2. The electromagnetic wave is transmitted from the transmitter into the compacting member at a predetermined interval while moving on the surface of the compacting member with the transmitter and the receiver being appropriately spaced apart from each other. The method for determining the degree of compaction of a compaction member according to claim 1.