JP2580550Y2 - Ground strength detector - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to a device for detecting ground strength by utilizing a reaction force received from the ground or a sand pile. In the present specification, the ground strength is not limited to the literal strength of the ground, but also includes the strength of a formed pile such as a sand pile.

[0002]

2. Description of the Related Art An apparatus of this kind is attached to a casing used for sand pile formation, for example, and continuously detects the ground strength and soil properties (and the properties of the formed sand pile) at each depth when the casing penetrates. At the same time, it is possible to evaluate not only the quality of the ground and the formed sand pile, but also the optimum specifications and the like when setting the construction method and the construction machine. The principle of the device is that it is attached to the lower end of the casing and detects the reaction force received by the oil pressure sensor via the cone due to the penetration of the casing (Japanese Patent Publication No. 3-2673).
No. 0) or a structure in which the displacement due to the reaction force of the strain body fitted with strain gages for detecting (JP-A No. 3 -17531).

[0003]

In the above conventional apparatuses, all of them detect the reaction force received by the penetrating movement of the casing. For this reason, when a small reaction force detection unit (the device of Japanese Patent Publication No. 3-26730) is fixed to the lower end of the casing, it may be affected by the magnitude of the penetration speed structurally due to the properties of the ground. . On the contrary, if the径全of the casing lower portion and the reaction force detecting portion of the reaction force meter i.e. a large (device of JP-A No. 3 -17,531), accurately measure the ground strength regardless lowering speed of the casing Although it was possible, it became clear that it became more susceptible to the influence of the ground properties around the piles, making it difficult to accurately grasp the ground strength.

Therefore, the object of the present invention is to improve accuracy and reliability. In particular, the strength of the ground to be measured is detected with higher accuracy without being affected by the strength of the ground around the sand pile. It is an object of the present invention to provide a ground strength detecting device which can be made and has no influence of a casing diameter, a penetration speed or the like.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention relates to a ground strength detecting device for detecting ground strength using a reaction force received from the ground or the like. The gist of the invention is that a cylinder is fixedly arranged at the lower end of the casing so that the piston rod can protrude from directly below the lower end of the casing, and a reaction force detector is provided at the protruding end of the piston rod. Further, in the device configuration, it is more preferable that the piston rod and the reaction force detecting unit are disposed substantially at the axis of the lower end of the casing.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. The ground strength detecting device 1 shown in FIGS.
It has a cylinder 3 fixedly disposed so as to protrude directly below the lower end of a sand pile forming casing 2, and a reaction force detector 5 is provided at a protruding end of a piston rod 4 constituting the cylinder 3.

[0007] The reaction force detector 5 includes a strain body 6 and a case 7.
And upper and lower flanges 8, 9 and the like. The flexure element 6 is provided with a concave section 6a around the outer circumference, and a plurality of strain gauges 10 are mounted on the concave section 6a. One end of a lead wire 11 is connected to the strain gauge 10. The other end of the lead wire 11 is guided to the upper end face side from a hole provided in the strain body 6, from which the piston rod 4, the barrel 12 of the cylinder 3, and the protection tube 13 provided along the outer periphery of the casing 2.
And the like, and is led out to the upper part of the casing 2. The upper side of the strain generating element 6 is formed as a male screw of the small diameter portion 6b, and is screwed to a female screw on the inner periphery of a hole 8a provided in the upper flange 8. The upper flange 8 is screwed into the small-diameter portion 6b and the hole 8a, and the upper part of the flexure element 6 is provided with a detent bolt 19c which is vertically screwed from the bottom surface of the concave portion 8b provided on the upper side to the flexure element 6 side. It is fixed to the outer periphery. A female screw 8c corresponding to the male screw 4a provided at the protruding tip portion of the piston rod 4 is formed on the inner periphery of the concave portion 8b. The lower flange 9
It is fixed to the lower end surface of the flexure element 6 by a final tightening bolt 19a, and can be replaced only when worn out. The case 7 has a cylindrical shape engaged with the outer diameter of the strain body 6 and is formed slightly shorter than the interval between the upper and lower flanges 8 and 9, and has a concave portion 6 a between the upper and lower flanges 8 and 9.
In order to maintain watertightness with a seal ring 14 therebetween and to provide a gap with the lower flange 9, a force acting on the lower flange 9 is received only by the flexure element 6.
The outer circumference is covered. In addition, the upper periphery of the case 7 is fixed to the strain body 6 with bolts or the like.

The above-described reaction force detecting section 5 includes a piston rod 4
Is connected to the protruding end. In this connection, in addition to the screwing of the female screw 8c and the male screw 4a, the rotation is prevented by tightening with bolts 19b from holes provided on the outer periphery of the concave portion 8b and the outer periphery of the male screw 4b. The cylinder 3 has a structure in which the piston rod 4 protrudes and retracts by operation of hydraulic pressure or the like, and hydraulic oil is fed to or discharged from the cells 16a and 16b through oil circuits 15a and 15b formed in the barrel 12. The hydraulic oil is introduced through a pipe arranged in the protective tube 13,
When hydraulic oil is pressure-fed from the cell 16a side, the piston rod 4 slides inside the barrel 12 and protrudes outward, and conversely, when hydraulic oil is pressure-fed from the cell 16b side, the piston rod 4 is moved to the barrel 12a. It slides inside and moves in the sinking direction. FIG.
Reference numerals 14b and 14c are seal rings. Also,
The cylinder 3 is fixedly disposed directly below the lower end of the casing 2. As shown in FIG. 2, this fixing structure is attached using an attachment flange 17 fixed to the inner periphery of the lower end of the casing 2. The thickness and shape of the flange 17 are set so as not to impair the discharge of sand and the like put in the casing 2. In order to fix the cylinder 3, it is preferable that the piston rod 4 and the reaction force detector 5 are arranged on a substantially axis at the lower end of the casing 2 as shown in FIG. You may.

[0009]

In the ground strength detecting device 7 having the above-described structure, for example, after the lower end of the casing 2 has penetrated to the depth to be measured below the ground, as shown in FIG. In the case, the compacted sand pile part 1 formed stepwise
When the lower end of the casing 2 is located at the position 8a, the cylinder 3 is driven to detect the reaction force received from the ground or the sand pile portion 18a (particularly the center) received in the process of pushing out the piston rod 4. It becomes possible. That is, in the process in which the piston rod 4 is pushed out, the flexure element 6
Is distorted according to the penetration resistance acting on the lower flange 9 (proportional to the ground strength), so that the ground strength at the penetration point of the casing 2 is measured by sending the output of the strain gauge 10 to an arithmetic circuit by an electric signal. You can do it.

[0010]

As described above, the ground strength detecting device of the present invention is different from the conventional device for detecting the reaction force received by the penetrating movement of the casing, and the piston rod is pushed out by driving the cylinder. The reaction force can be detected in the process, and the reaction force is hardly affected by the diameter and the penetration speed of the casing, and the ground strength and the ground properties can be detected more accurately. At the same time, the piston rod for attaching the reaction force detection unit is provided so as to be able to protrude from directly below the lower end of the casing. It is hardly affected by the properties of the ground around the pile, and can be detected with higher accuracy. According to claim 2,
The ground strength can be detected in the same manner as the N value by the standard penetration tester, and both high accuracy and reliability can be improved. Further, it is needless to say that the present apparatus can detect the ground strength and the sand pile strength while moving the casing.

[Brief description of the drawings]

FIG. 1 is a partially cutaway view showing a main part of a configuration of a ground strength detecting device of the present invention.

FIG. 2 is a partially cutaway view showing the device attached to a casing.

FIG. 3 is a schematic view showing the principle of the device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ground strength detection device 2 Casing 3 Cylinder 4 Piston rod 5 Reaction force detection part

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Osamu Ishida 1419-2, Komaha, Sawamachi, Sarushima-gun, Ibaraki Prefecture (72) Inventor Tatsuya Ito 1419-3, Komahane, Sawamachi, Sarushima-gun, Ibaraki JP-A-61-183516 (JP, A) JP-A-56-64489 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) E02D 1/02 E02D 3/10 104

Claims (2)

(57) [Scope of request for utility model registration] In a ground strength detecting device for detecting ground strength by utilizing a reaction force received from the ground or the like, a piston rod can protrude from a lower portion of a casing penetrating into the ground or a formed pile from directly below a lower end of the casing. A detection device for detecting ground strength or the like, comprising a cylinder fixedly disposed in a state, and a reaction force detection unit provided at a protruding end of the piston rod. 2. The ground strength detecting device according to claim 1, wherein the piston rod and the reaction force detecting unit are disposed substantially on an axis at a lower end of the casing.