JPS6342227B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a construction status inspection device for a structure.
More specifically, the present invention relates to a device for inspecting the consolidation state and construction area of ground consolidated by an injection method or the like.

It is generally difficult to know from the outside the state and degree of consolidation of structures consolidated with chemical solutions or concrete. It is extremely difficult to know the construction area and consolidation state of the ground constructed using the chemical injection method for in-ground foundation work.

Construction using the injection method is widely used for ground improvement and water stoppage during foundation construction. In this construction method, the ground is bored and a chemical solution is forced into the hole to penetrate and harden a certain area of the ground. However, since the ground generally consists of complex strata, the chemical solution may escape outside the planned area or may not solidify sufficiently, making it difficult to carry out construction as planned. Since construction defects in foundation work that occur in this way can lead to serious accidents, it is particularly desirable to develop a practical device that can reliably inspect the construction status of the construction ground.

A method using radioactive materials and an electrical method to measure the resistivity of the ground have been reported as methods for inspecting the ground for construction using the injection method. However, both are indirect inspection methods, and it is difficult to determine the construction status such as the hardness of the construction ground and the shape.

The present invention provides an inspection device that uses ultrasonic waves to solve the above-mentioned difficulties, that is, an inspection device that inspects the solidification state and construction area of a structure.

According to this invention, the construction range and solidification state of a structure can be inspected using an inspection device composed of an electromagnetic ultrasonic generator and a hydrophone. That is, a pulsed ultrasonic wave is emitted by an ultrasonic generator of the inspection device provided inside or outside the structure. The emitted ultrasonic waves travel within the ground and are reflected at the boundaries and internal heterogeneous areas of the structure. This reflected wave is detected by the hydrophone. By measuring the time interval between the emitted wave and the received wave, the attenuation rate, etc. at this time, the shape and solidification state of the structure can be measured.
Moreover, the solidification state can also be known by measuring the transmitted waves.

Hereinafter, it will be explained in detail using the drawings. FIG. 1 shows one embodiment of the invention. The ultrasonic transmitter 3 and the pressure hydrophone 2 are inserted into the injection hole 4 of the internal material of the construct 1 solidified by the drug injection method. The ultrasonic transmitter 3 is connected to the output side of the function generator and the power amplifier, and is controlled by the pulse generator to generate pulsed ultrasonic waves. The generated ultrasonic waves propagate inside the construct and are reflected at the boundaries of the construct 1. The reflected ultrasound waves are detected by a pressure hydrophone. By amplifying the detection signal with a voltage amplifier and detecting it with an oscilloscope, it is possible to measure the time interval or attenuation rate between the transmitted wave and the received wave. When there is a sensing device outside the structure, the fastest signal among the reflected waves is the reflection from the building boundary closest to the sensing device. Furthermore, by measuring at several locations outside the structure, it is possible to obtain an outline of the shape of the structure.

FIG. 1 shows an example in which an ultrasonic transmitter and a pressure hydrophone are inserted into the same injection hole. When measuring by inserting an ultrasonic transmitter and a pressure-type hydrophone separately into adjacent injection holes, the ultrasonic waves from the ultrasonic transmitter are transmitted through the structure and detected by the pressure-type hydrophone. It is clear that in this case as well, it is possible to measure the passage time or attenuation rate of the ultrasonic waves, as in the example shown in FIG. If the effect of chemical injection is sufficient, the speed of sound will increase and the amount of attenuation will decrease. That is, the effect of the chemical solution can be detected.

If the speed of sound and the amount of attenuation of the sound wave are measured immediately after the chemical solution is injected, as the chemical solution hardens, the speed of sound increases and the amount of attenuation decreases. After curing, it becomes a constant value and does not change. If an unconsolidated portion exists between the two, reflection and refraction of sound waves occur due to the difference in acoustic impedance, resulting in increased attenuation. In this way, the state of the drug solution injector can be detected.

FIG. 2 shows the structure of an electromagnetic ultrasonic transmitter. A solenoid coil 8 filled with insulating resin 6 is provided inside the tubular diaphragm 5. It is connected to an external amplifier by a cable 9 and a connecting ring 7. When a large current is momentarily passed through the solenoid coil, the eddy current causes the tubular diaphragm to vibrate, generating ultrasonic waves. The frequency of the ultrasonic wave is approximately determined by the inductance of the solenoid coil and the capacitance of the external circuit. In this ultrasonic transmitter, by increasing the length of the tubular diaphragm, the directivity in the direction perpendicular to the cylindrical surface of the ultrasonic transducer can be improved. In other words, the directivity in a plane perpendicular to the central axis of the vibrator becomes very good. Since information on the averaged horizontal plane can be obtained in this way, by moving the inspection device consisting of an electromagnetic ultrasonic generator and a hydrophone up and down, it is possible to determine the solidification state or average shape of the injection body in the vertical direction. It becomes possible to measure. A solid body produced by injecting a chemical solution is generally pear-shaped, and is usually close to axial symmetry. Therefore, information averaged within the horizontal plane described above is also sufficiently effective.

This makes it possible to measure the horizontal plane of the construction shown in FIG. Therefore, the vertical structure of the construct can be known in detail. This fact is very important for construct state detection.

Figure 3 shows the structure of a pressure hydrophone. A soft insulating resin 15 is attached to the holder 13, a ring-shaped piezoelectric receiver 11 is placed thereon, and the whole is covered with a protective film 12. Connection ring 14 and cable 1
Connect to external circuit by 0. The ring-shaped piezoelectric body has electrodes provided on the outer and inner surfaces of the ring, and generates voltage in response to changes in external pressure. Since this receiver is cylindrical, it has a structure that allows it to be easily inserted into the injection hole 4 shown in FIG. In this example, a pressure-type hydrophone was used as the hydrophone, but based on the principle of the present invention, the hydrophone only needs to measure the arrival time and attenuation rate of ultrasonic waves, so other hydrophones, such as velocity-type hydrophones, may be used. It is clear that it may be used.

When solidified by the chemical injection method, for example, Toyoura standard sand has a sound velocity of about 1900 m/s. Note that the speed of sound in water is approximately 1500 m/s. In the case of rocks
The velocity ranges from around 2500m/s to over 6000m/s in some cases. Assuming a cylindrical structure with a diameter of 1 m, if a sound wave is emitted from the center of the cylinder, the reflected wave will appear in about 1.05 milliseconds in the case of the Toyoura standard sand mentioned above. In the case of water, it takes about 1.33 milliseconds. In this way, the time at which the reflected waves appear represents the properties of the structure. Similarly, the attenuation rate of reflected or transmitted waves is representative of the properties of structures in the path of the ultrasound. Therefore, the device of the present invention is very effective in detecting the construction status and structure of a building.

[Brief explanation of the drawing]

FIG. 1 shows one embodiment of the present invention, where 1 is a construction, 2 is a pressure hydrophone, 3 is an ultrasonic transmitter, and 4 is a hole. FIG. 2 shows the structure of the ultrasonic transmitter, in which 5 is a tubular diaphragm, 6 is an insulating resin, 7 is a connecting ring, 8 is a solenoid coil, and 9 is a cable. FIG. 3 shows a pressure type hydrophone, in which 11 is a receiver, 12 is a protective film, 13 is a holder, 14 is a connecting ring, and 15 is a soft insulating resin.

Claims (1)

[Claims] 1. An electromagnetic ultra-magnetic type device consisting of a solenoid coil inside a conductive tubular diaphragm is used in equipment that inspects the consolidation state of structures constructed underground over a certain area or the construction area by injecting and solidifying chemical solutions, etc. A construction status inspection device for a structure, comprising a sonic transmitter and an ultrasonic receiver using a cylindrical hydrophone as an ultrasonic receiver.