JPH09279559A - Discriminating method of geology - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reliably discriminate a change in the geology by acceleration data, and accurately recognize an arrival at the geology of a water impermeable layer or the embedment ground by arranging a piezoelectric element type accelerometer in a hollow part of a rod having an excavating head. SOLUTION: An excavating head 4 where bits 3 are implanted on the tip of a rod 2 is arranged on an auger 1. A piezoelectric element type accelerometer 5 housed inside a protective tube 6 is fixed to the vicinity to the excavating head 4 of a cement milk flowing passsage in the rod 2. In the piezoelectric element type acceleromemter 5, mass and a piezoelectric element are arranged in a case, and a phenomenon that electric charge in proportion to a change in the mass is generated since the mass is displaced to the case and applies force to the piezoelectric element when acceleration acts on the case, is utilized. Imapct and vibration are expressed by a variation per unit time of displacement, speed and acceleration. Since resistance to vibration, rotational tirque and rotating speed applied to the excavating head 4 becomes different in a geological condition of respective strata, and an arrival at the geology of the water impermeable layer or the embedment ground can be known by discriminating the geology.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a geological judgment method for judging the progress of excavation, for example, when excavating a pile hole as a foundation work in the fields of construction and civil engineering.

[0002]

2. Description of the Related Art In auger boring work, when it is necessary to excavate the impermeable layer geology or the ground to be embedded, it is necessary to confirm whether the auger tip (excavation head) has reached the impermeable layer. It is important to.

Conventionally, a boring survey was conducted in advance and confirmed, or it was controlled by a change in cutting resistance (torque) during auger drilling. This change in cutting resistance is the drive power (voltage or current) of the hydraulic motor that drives the rod to rotate.
It can be grasped by the change of.

As another method, the earth and sand discharged at the time of drilling was visually confirmed.

[0005]

Among such conventional methods, the boring survey in advance needs to be carried out before the construction starts, which requires extra time and labor, and the geology of the impermeable layer before the construction starts. Alternatively, even if the depth to the rooting ground is detected, accurate detection is impossible if the rod is bent during excavation.

In the control by changing the cutting resistance (torque), the change of the tip cutting resistance cannot be clearly grasped under the influence of the peripheral resistance, the resistance of the auger bending, the excavation load, and the excavation speed. I can't confirm.

Confirmation by visual inspection lacks certainty.

The object of the present invention is to solve the disadvantages of the above-mentioned conventional example, to reliably identify the geology at the time of cutting, and to accurately know the impermeable layer geology or the arrival at the rooting ground. To provide a method of determining

[0009]

In order to achieve the above object, the present invention firstly provides a piezoelectric element type accelerometer in the hollow portion of a rod having a drilling head, and acceleration data from this piezoelectric element type accelerometer. Discriminating changes in the geology, secondly, the piezoelectric element type accelerometer should be installed at or near the excavation head portion, and thirdly, the rod having the excavation head should be installed in a plurality of multi-axis excavator rods. The gist is to provide a piezoelectric element type accelerometer on one of the rods.

According to the first aspect of the present invention, the rod having the excavating head changes rotational torque, speed, vibration, etc. due to the hardness of the formation, and such changes are detected by the piezoelectric element type accelerometer, The acceleration data can be used to make the determination. Moreover, since the piezoelectric element type accelerometer is installed inside the rod, it does not interfere with cutting.

According to the second aspect of the present invention, in addition to the above-mentioned action, the piezoelectric element type accelerometer is installed at or near the excavation head portion, so that influences such as circumferential surface resistance and rod bending resistance are exerted. By making it small, it is possible to accurately detect the difference due to the vibration characteristics of the excavation head portion.

According to the present invention as set forth in claim 3, it is a case where it is provided in a multi-axis excavator used for construction of an underground wall by pillar piles of soil cement, one of which is a piezoelectric element type. By providing an accelerometer, it is possible to accurately know the depth of the entire excavator, the geology of the impermeable layer, or the arrival at the rooting ground.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a side view showing a first embodiment of a geological determination method of the present invention, FIG. 2 is a cross-sectional plan view of the essential parts of the same, and FIG. 3 is a side view of the essential parts of the same. Is the case.

As is well known, the auger 1 is provided with an excavation head 4 having a bit 3 planted at the tip of a rod 2. Although not shown, the rod 2 can be replenished as appropriate, and the upper end thereof is connected to a drive device incorporating a hydraulic motor and a speed reducer.

Further, the drive unit and the rod 2 are hung up and down freely from the top sheave of the leader mast standing on a heavy machine such as a crawler, and the drive unit moves up and down along the leader mast with the leader of the leader mast as a guide. .

The rod 2 is a hollow tube, and the inside thereof is used as a flow passage for discharging cement milk from the tip of the drilling head 4.

In the present invention, the piezoelectric element type accelerometer 5 is provided in the rod 2. The piezoelectric element type accelerometer 5 is placed inside a protective tube 6 having a diameter of 8 cm and a length of about 1 m, and is fixed in the flow passage of the rod 2 by, for example, a magnet or the like. Further, in the present embodiment, it is provided near the excavation head 4.

The piezoelectric element type accelerometer 5 has a mass and a piezoelectric element (crystal) arranged in a case. When acceleration acts on the case, the mass is displaced with respect to the case and Since a force is applied, the fact that a charge proportional to this change in mass is generated is used. The impact and vibration can be expressed by the amount of change in “displacement, velocity, acceleration” per unit time.

Measurement data from the piezoelectric element type accelerometer 5 is guided to the ground by wire or wirelessly passing through the rod 2, introduced into a measurement control device (monitor) such as a computer, and displayed on an output device such as a monitor or a printer. Etc. and output.

For example, when the rod 2 is bent, the vibration applied to the rod 2 due to the bending increases as the depth increases. If the piezoelectric element type accelerometer 5 detects such a gradual increase in vibration, the existence of bending can be grasped.

The geology is, for example, as shown in FIG.
Depending on the structure of surface soil such as embankment, loam-mixed gravel layer, boulder layer, supporting ground such as basalt, silt layer, boulder layer, pelitic schist, etc., vibration applied to the drilling head 4 in the geological condition in each layer Since the rotational torque and the resistance to the rotational speed are also different, it is possible to determine the geology by observing these changes, and it is possible to know that the impermeable layer geology or the rooting ground has been reached.

Strictly speaking, when a small crack is generated in the ground or rock as a precursor of destruction, a sound of several hundreds of hertz to several tens of kilohertz may be emitted. The change in geology can be understood by picking up the passing vibration.

The difference is that sound is produced over the entire area of gravel, sound of high frequency band is produced by sand, and sound is hardly produced by clay.

FIG. 4 is a front view showing a second embodiment of the present invention, in which the excavator is a multi-axis excavator having a plurality of rods 2 each having an excavating head 4. In such a multi-axis excavator, the piezoelectric element type accelerometer 5 is provided in one of the plurality of rods, for example, in the central rod. The rod 2 is provided with a moving blade 7 made of a screw and a kneading blade 8 made of a vertical blade at an upper and lower relative position, and is a dedicated machine for an in-situ soil mixing method (SMW method) as a multi-axis excavator.

As described above, even if the piezoelectric element type accelerometer 5 is provided on only one of a large number of rods, it is possible to accurately know the depth of the entire excavator and the geology of the impermeable layer or the arrival at the rooting ground. it can.

[0026]

INDUSTRIAL APPLICABILITY As described above, the method for discriminating geology of the present invention can surely discriminate the geology at the time of cutting without going through a preliminary step, and as a result, the impermeable layer geology or roots. It is possible to know exactly the arrival at the ground.

[Brief description of drawings]

FIG. 1 is a side view showing a first embodiment of a geological determination method of the present invention.

FIG. 2 is a cross-sectional plan view of essential parts showing a first embodiment of the geological determination method of the present invention.

FIG. 3 is a side view of an essential part showing a first embodiment of a geological determination method of the present invention.

FIG. 4 shows the geological determination method of the present invention. It is a front view showing an embodiment.

[Explanation of symbols]

 1 ... Auger 2 ... Rod 3 ... Bit 4 ... Excavation head 5 ... Piezoelectric element type accelerometer 6 ... Protective tube 7 ... Moving blade 8 ... Kneading blade

Claims (3)

[Claims] 1. A geological determination method comprising: providing a piezoelectric element type accelerometer in a hollow portion of a rod having an excavation head, and discriminating a change in the geological characteristic based on acceleration data from the piezoelectric element type accelerometer. 2. The geological judgment method according to claim 1, wherein the piezoelectric element type accelerometer is installed in the excavation head portion or in the vicinity thereof. 3. The geological determination according to claim 1 or 2, wherein a plurality of rods having an excavating head are rods of a multi-axis excavator provided side by side, and one of them is provided with a piezoelectric element type accelerometer. Method.