JPH03125910A - Measuring method for distance in underground cavity - Google Patents

Abstract

PURPOSE:To enable reliable measurement of a distance in an underground cavity by a method wherein an anchor fitted with a wire material is installed in the bottom of the underground cavity and an ultrasonic sensor is made to engage with the wire material and to rise, guided by the wire material. CONSTITUTION:An anchor 3 is set in the bottom of an excavated hole 1 filled with muddy water and a stretched wire 4 is connected to the central part of the anchor 3, while an ultrasonic sensor 2 is made to engage elevatably with the stretched wire 4. Then, the stretched wire 4 is pulled to be a straight line, while the anchor 3 is held to be set in the bottom of water of the excavated hole 1, and the wire is put in a state wherein the total length thereof is in accord substantially with the center line of the excavated hole 1. In this condition, the sensor 2 is raised slowly with the stretched wire 4 used as a guide member, and a distance from the sensor 2 to the wall of the hole is measured. When measured data are inputted to an arithmetic element 6 on the ground through a transmission cable 5, the arithmetic element 6 calculates the cross sectional area of the hole at each depth and thus the volume of the excavated hole 1 can be computed.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is a method for measuring underground cavities that can accurately measure the diameter at each depth, which is the basic data for determining the cross-sectional area and volume of a cavity excavated into the ground. Concerning the distance method.

<Conventional technology> For example, when drilling a hole with a total length of 100 meters to what depth and pouring concrete to construct a foundation pile, it is necessary to know the exact volume of the excavated hole in order to measure the amount of concrete used. It is necessary to do so.

In particular, when a hole is drilled across a collapsible stratum, it is extremely difficult to accurately determine the volume of the hole.

Conventionally, a measurement method using an ultrasonic sensor is known as a means for determining this type of volume.

Regarding this measurement method, a waterproof ultrasonic sensor suspended from a lobe material, etc. is dropped into a borehole filled with muddy water, and ultrasonic waves are emitted from the ultrasonic sensor into the muddy water. The distance to the wall is measured, and based on this measurement data, a computer calculates the cross-sectional area at each depth and the volume of the borehole.

<Problems to be Solved by the Present Invention> The conventional technique for measuring the volume of an excavated hole described above has the disadvantage that it cannot measure a cavity that extends in a direction other than the vertical direction, for example, in an oblique direction.

Further, there is a drawback that the ultrasonic sensor tends to be twisted under the influence of the convection phenomenon of the stabilizing liquid such as muddy water, and the ultrasonic sensor tends to meander due to the resistance of the stabilizing liquid.

Therefore, the reliability of ranging data at each depth is low.

<Objective of the present invention> The present invention has been made to solve the above-mentioned problems, and its seven objectives are to accurately measure distance within an underground cavity by aligning an ultrasonic sensor along the center of the underground cavity. The object of the present invention is to provide a distance measuring method for underground cavities.

<Means for Solving the Problems> That is, the present invention provides an underground cavity ranging method for measuring the distance of a cavity formed underground using an ultrasonic sensor, which includes attaching an anchor to one end of a wire, and An ultrasonic sensor is moored to the wire so that it can be raised and lowered, the wire is inserted into the underground cavity, the anchor is installed at the bottom of the underground cavity, the wire exposed above the ground is stretched out in a straight line, and the wire is guided by the wire. This is a distance measuring method for underground cavities, which is characterized by measuring distance by raising a sound wave sensor.

<Description of the present invention> The present invention will be described below with reference to the drawings. First, we will explain the main equipment used for distance measurement.

Kui〉Ultrasonic sensor The ultrasonic sensor 2 uses a known waterproof sensor.

As a means for mooring the ultrasonic sensor 2 to the tension wire 4 so as to be moored up and down, for example, as shown in FIG. A conceivable method is to provide a plurality of sets around the cylindrical member 7 and insert the tension wire 4 into the hole at the center of the cylindrical member 7 for mooring.

Further, the ultrasonic sensor 2 may be of a type that uses one sensor for both transmitting and receiving ultrasonic waves.

Further, the ultrasonic sensor 2 may be lifted using the transmission cable 5, or a lobe material exclusively for lifting may be used.

<Exposure> For the anchor anchor 3, a conventional packer that expands and contracts by supplying and discharging fluid into a flexible bag is used, or a weight such as a steel ball is used.

When using a backer for the anchor 3, it is necessary to connect a hose for supplying fluid such as water from the ground.

<Action of the present invention> Next, a distance measuring method for the cavity will be explained.

In Figure 1, 1 is an excavation hole that is an underground cavity.
filled with muddy water.

In the present invention, in order to obtain the cross-sectional area and volume at each depth of the borehole 1, the ultrasonic sensor 2 is operated as follows.

That is, a tension wire 4 such as a cableway or a lobe is connected to the center of an anchor 3 that can be installed at the bottom of an excavation hole 1, and an ultrasonic sensor 2 is moored to this tension wire 4 so as to be movable up and down.

Then, with the anchor 3 in a state where it does not float on the bottom of the water in the excavation hole 1, the tension wire 4 extending above the ground is pulled until it becomes straight.

At this time, since the lower end of the tension wire 4 is temporarily fixed almost at the center of the excavation hole 1, if the upper part of the tension wire 4 is aligned with the center of the excavation hole 1, the tension wire 4 in the middle will inevitably fall into the borehole 1. It almost coincides with the center line of

With the entire length of the tension wire 4 approximately aligned with the center line of the borehole 1, the ultrasonic sensor 2 is slowly raised using the tension wire 4 as a guide member, and the ultrasonic sensor 2 is moved from the ultrasonic sensor 2 at each depth to the borehole 1. Measure the distance to the hole wall.

Incidentally, in the processing after measurement by the ultrasonic sensor 2, for example, the measurement data is inputted to the calculation unit 6 on the ground via the transmission cable 5 connected to the ultrasonic sensor 2.

A calculation unit 6 calculates the cross-sectional tank for each depth based on the measurement data of the ultrasonic sensor 2, and calculates the final volume of the excavation hole 1.

The calculation unit 6 displays the calculated data on a monitor or prints it out.

When the measurement is completed, the anchor 3 is recovered together with the tension wire 4.

Since the ultrasonic sensor can be moored to the stretched wire, it can be operated in a straight line.

<Mouth> Even if the cavity extends diagonally other than vertically, it can be accurately measured.

[Brief explanation of the drawing]

Fig. 1 2 Conceptual diagram of distance measuring method for underground cavities according to the present invention Fig. 2: Cross-sectional view taken along ■-H in Fig. 1 <Effects of the present invention> The present invention has the following effects as explained above. is obtained. <B> With conventional methods, it was not possible to operate the ultrasonic sensor stably.

Claims (1)

[Claims] (1) In an underground cavity distance measurement method in which a cavity formed underground is measured using an ultrasonic sensor, an anchor is attached to one end of a wire, and the ultrasonic sensor is moored to the wire so that it can be raised and lowered. , A wire rod is inserted into an underground cavity, an anchor is installed at the bottom of the underground cavity, the wire rod exposed above the ground is pulled and stretched in a straight line, and the ultrasonic sensor is guided by the wire rod to ascend and measure distance. A distance measurement method for underground cavities.