JPS63308110A - Measurement of degree of compacting ground - Google Patents

Abstract

PURPOSE:To judge the degree of compaction of the ground immediately by a method in which a weight is collided with the ground, the impact force and the responding speed of the ground are detected, and the compacting degree of the ground is measured on the basis of the ratio of the impact force to the responding speed as an indicator. CONSTITUTION:A measurer consists of a weight 1, a tip 2, a load meter 3, and an acceleration meter 4. The weight 1 is dropped onto the ground after or during compaction from a proper height. The impact force F at the time of collision with the ground and the responding speed V of the ground are detected to obtain the F/V ratio as an indicator. The quality of the compacted ground can thus be exactly controlled by feeding the results of measurement back.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical field to which the invention pertains) The present invention relates to a technique for measuring the degree of compaction of ground after or during compaction.

(Problem to be solved by the invention and its characteristics) Conventionally, the degree of compaction of soil in earthworks has generally been determined by determining the dry density of compacted soil using a unit volume weight test. Not only is it difficult to conduct tests at multiple locations because it requires a considerable amount of labor over time, but the test target is usually limited to soil after compaction has been completed, and it is difficult to conduct tests in the original sense. Not useful for quality control of soil compaction work. Additionally, unit volume weight testing is a destructive testing method because it typically involves drilling holes in the ground to collect samples.

There is also a known method of dropping a weight from a predetermined height and colliding with the ground, detecting the maximum acceleration at the time of collision, and estimating the density of the ground from this (Japanese Patent Laid-Open No. 51-117402).
(see issue), the acceleration waveform is affected by the particle structure of the ground and does not necessarily accurately reflect the density and strength of the ground. Repeat dropping the weight (usually about 8 times)
This results in a lack of immediacy and continuity in measurement.

The present invention can instantly, non-destructively, and quickly improve the degree of compaction of not only soil after compaction, but also soil that is currently being compacted.
The object of the present invention is to provide a simple method capable of continuous measurement, and its structural features are as described in the claims.

In the present invention, the impact force F is detected by a load meter attached to the weight, and the response speed V of the ground is detected by integrating the detected value of the accelerometer attached to the weight using an attached calculation device. F
/v is generally calculated using an arithmetic unit.

(Detailed description of the invention) - When i is the force applied to an object, F is the response speed of the object to this, and the ratio of F and V is Z, 2 is the dynamic stiffness of the object) represents.

The present invention focuses on the fact that when the object is compacted soil, Z shows a good correlation with the dry density of compacted soil determined by a unit volume weight test and the ground coefficient determined by a flat plate loading test, and uses Z as an index. It is designed to measure the degree of compaction of soil.

2, there are three ways to excite an object: harmonic vibration, random vibration, and impact vibration. Since shaking is optimal and the device is simple, in the present invention, a weight is allowed to fall freely from an appropriate height and is caused to collide with the ground to be measured to generate vibration due to the impact.

In general, when two objects having ZO and Zl collide, the force F that occurs between the contact points of the two objects is: Here, if Zo is the Z value of the weight of the measuring device and Zl is the Z value of the compacted ground, then in general, Z . ) Z+ is established, and (1
) formula is Zl/zO嬌0yotsu, Z 1= F / v −−−−−−−−
--- (2) is obtained, and by measuring the impact force F at the time of collision and the response speed V of the ground, the Z value of the compacted ground can be calculated from equation (2).

In order to know the dry density and soil coefficient of the ground from the binary values of the measured compacted ground, a correlation diagram created in advance may be used.

The drawing is an explanatory diagram of the apparatus for implementing the present invention (-example), and the first
In the figure, 1 is a weight, 2 is a tip, 3 is a load meter, and 4 is an accelerometer.

The weight of the weight 1 is usually several pounds, and is appropriately selected in consideration of the soil quality and layer thickness of the ground to be measured.

It is preferable that the lower surface of the tip part 2 (the surface in contact with the soil) be flat, and that the material of the tip part 2 be made of hard and lightweight duralumin or the like.

The load cell 3 and the accelerometer 4 are piezoelectric sensors, and the load cell 3
Two to three accelerometers are provided, and one accelerometer 4 is provided.

In FIG. 2, 5 is a data processing section, 6 is a display section, and 7 is a storage/reproduction section.

The data processing section 5 adds load meter data, converts acceleration data into velocity data by integrating it, and calculates Zl using the above equation (2).

The display section 6 is a liquid crystal display or the like, and is designed to inform the operator of the measurement results.

The storage/reproduction section 7 is connected to the display section 6 so that it can reproduce stored data and calculation results and send them to the display section 6.

For example, by installing the above-mentioned device on a vehicle towed by a road roller, and repeatedly lifting and dropping the weight 1 using an appropriate mechanism while moving the road roller, it is possible to perform soil compaction work in parallel with the ground compaction work. The degree of compaction can be measured continuously.

(Effects of the Invention) Since the present invention is as described above, the following effects can be expected.

The degree of compaction of soil can be determined instantly, and accurate quality control of compacted ground is possible by feedback of measurement results.

Since it is a non-destructive measurement, the measurement ground is not disturbed.

Continuous measurement is possible, unlike traditional point management,
Area management can be performed, variations in the quality of the compacted ground are reduced, and homogeneous compaction can be performed.

Since the measured value Z1 is the ratio of the input (excitation force) to the output (velocity response), it is not affected by the falling height of the weight and can be simplified both in terms of equipment and operation. .

[Brief explanation of the drawing]

The drawings are explanatory diagrams of an apparatus for implementing the present invention; FIG. 1 is a side view of a weight, and FIG. 2 is a block diagram of data processing. In the figure, 1 is a weight, 2 is a tip, 3 is a load cell, 4 is an accelerometer, 5 is a data processing section, 6 is a display section, and 7 is a memory/memory section.
This is the reproduction department. Representative Patent Attorney Hiroshi Sometani Figure 1 Figure 2

Claims (1)

[Claims] A weight that is freely dropped from an appropriate height collides with the ground after compaction or during compaction, and the impact force F at the time of collision is calculated.
A method for measuring the degree of compaction of the ground, comprising: detecting the response speed v of the ground and the response speed v of the ground, and measuring the degree of compaction of the ground using the ratio of the two (F/v) as an index.