JPH0587657A - Ground supporting force tester - Google Patents

Abstract

PURPOSE:To obtain a ground supporting tester, which is compact, light-weight and easy to handle. CONSTITUTION:In a ground supporting force tester, a load mounting plate 14 having a through hole 15 at the central part is provided on the ground. The load of a falling weight 20 is applied on the load mounting plate through a cabinet 17 having a load detector. A deflection detecting lever 22, which is in contact with the ground by way of a hole, is supported with the cabinet. When the load is applied, the falling speed of the deflection detecting lever 22 is detected with a speedometer 24. The supporting force of the ground is tested based on the impact load obtained with the load detector and the deflecting amount obtained with the speedometer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ground bearing force testing device, and more particularly to a ground bearing force testing device for pavements, roadbeds, subgrades and the like.

[0002]

2. Description of the Related Art Generally, a road is composed of a pavement that is roughly classified into asphalt concrete pavement and cement concrete pavement, a roadbed that supports the pavement, and a ground such as a roadbed below the pavement.

At the time of newly constructing a road or the like, a ground supporting force testing device is applied to quality control and inspection of each component. In addition, in order to carry out planned maintenance and repairs on roads that are in use, the current state of damage and deterioration of the pavement, roadbed, and subgrade,
A ground bearing capacity tester is used to grasp the time-series changes in damage and obtain data that determines the method and scale of maintenance and repair, the timing, etc.

The following is known as a conventional ground supporting force testing device.

(1) On-site CBR test equipment

FIG. 6 shows this on-site CBR test equipment.
Is ground, 2 is a penetration piston having a diameter of 50 mm, 3 is a load meter, 4 is a screw jack, 5 is a ball seat, 6 is a reaction force load device, and 7 is set at a position separated from the penetration piston 2 by 500 mm or more. A fixed point, 8 is a dial gauge for measuring the change in height between the fixed point 7 and a predetermined point of the penetrating piston 2.

In this apparatus, a reaction force load device 6 is placed on a pavement body, a penetration jack 2 is penetrated into a roadbed by a screw jack 4, and the load and the penetration amount at this time are measured.

(2) Benkelman beam tester for pavement

In this apparatus, as shown in FIG. 7, a track 9 of a multi-wheel tire having a wheel load of 5 tons is prepared, and the tip of a Benkelman beam 10 is inserted into the multi-wheel tire to insert the track 9 into the track 9.
Move and measure the amount of deflection at that time.

(3) Plate loading test device

In this device, as shown in FIG.
The loading plate 11 of mm is placed on the roadbed of the ground 1, for example, and loaded by the 5-ton jack 12, and the loading plate 11 is penetrated with the fixed point 7 set at a position separated from the loading plate 11 by more than about 1.5 m as a reference. Measure the amount.

[0012]

[Problems to be Solved by the Invention] However, on-site CBR
In the test device, in order to measure the amount of movement of the penetrating piston 2, a fixed point 7 is set in an area 500 mm or more away from the measurement point, and a dial gauge for measuring the height difference between the fixed point 7 and the penetrating piston 2. It is necessary to use 8 and at least a load device 6 for reaction force of 5 tons,
There are drawbacks such as the size and cost of the device, and the time required to set up the device for testing.

Further, the Benkelman beam test apparatus for pavement has the drawbacks that a track of a dual-wheel tire and a load of 5 tons are required, and it takes time to prepare for the test.

In addition, the flat load tester requires a load device 6 for reaction force of at least 5 tons, it takes time to prepare for the test, and when the roadbed or roadbed of the road being used is tested, the diameter of the pavement is increased. There is a defect that it is necessary to make a hole of 300 mm or more.

The present invention is designed to eliminate the above drawbacks.

[0016]

A ground supporting force testing apparatus of the present invention has a through hole in a central portion thereof, a loading plate placed on the ground, and a load detector placed on the loading plate. Housing and
A heavy sword dropped onto this housing, a drop height adjusting mechanism for this weight, and a ground supported by the housing so that its lower end is in contact with the ground through the through hole of the packing plate described above. The deflection detecting rod, a speedometer for detecting the descending speed of the deflection detecting rod, the impact load obtained from the load detector and the amount of deflection obtained from the speedometer are used to count the bearing capacity of the ground. ..

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

The device of the present invention was invented based on the following principle.

(1) When a weight having the same mass is dropped from the same height, the generated impact load should always be the same. However, when the ground that receives a load, for example, the pavement is soft or hard, the impact load is different because the rate at which the load is absorbed by the pavement is different. Therefore, the generated impact load is measured and the quality of the pavement is judged based on the load difference. (However, it applies to pavements constructed under the same conditions). Further, the same can be determined by the amount of deflection (displacement amount) of the ground at that time. That is, when an impact load is applied to the pavement, the amount of deflection is large if the pavement is soft and the amount of deflection is small if the pavement is stiff.

(2) When constructing the ground, such as a pavement, the physical and chemical qualities of the materials used, the construction layer thickness, etc. are determined. Therefore, by measuring the amount of surface deflection and circular load of the pavement when only one circular load with a uniform stress distribution acts vertically, it is possible to determine whether or not the construction is being performed as designed. .. Moreover, if this measurement is performed regularly, it is possible to judge the deterioration of the material and the reduction of the bearing capacity due to the traffic load.

Further, the tensile strain generated on the lower surface of the pavement layer can be calculated from the surface deflection, and when the strain amount is known, the fatigue curve (strain-
From the number of fatigue fractures), it is possible to estimate the time when cracks will occur and determine the time to repair the current pavement.

In the present invention, as shown in FIG. 1, a rubber plate 13 is attached to the lower surface, for example, a loading plate 14 having a diameter of about 95 mm is provided with a hole 15 having a diameter of about 10 mm through the rubber plate 13 and the loading plate 14. The loading plate 14 is placed on the ground 1 to be tested, the housing 17 having the load detector 16 is placed on the loading plate 14, and the buffer 18 is mounted on the housing 17. The weight 20 of, for example, 20 kg is attached to the guide column 21 from a predetermined height determined by the drop height adjusting mechanism 19 via the
It is possible to fall along the
And the deflection detection rod 22 whose lower end is in contact with the ground 1 through the through hole 15 of the rubber plate 13 is supported by the casing 17 via the pressing spring 23, and the load plate 14 is subjected to an impact load. The downward speed of the deflection detecting rod 22 resulting from the downward deflection of the ground 1 when is applied is measured by the speedometer 24. In addition, 25 is a handle part of the ground support force testing device, and 26 is a measurement value processor.

Since the ground supporting force testing device of the present invention has the above-mentioned structure, when carrying out the bearing supporting force test of the ground 1, the grip portion 21 is held and the loading plate 14 of the ground supporting force testing device is inserted via the rubber plate 13. It is placed on the ground 1 and the fall height adjustment mechanism 1
If the weight 20 is dropped onto the housing 17 from a height determined by 9, for example, a height of 850 mm, the impact force due to this is transmitted to the ground 1 via the loading plate 14, and this portion of the ground 1 is thereby transmitted. Is flexed downward relative to the other parts of the ground 1, and the flexure detection rod 22 is also lowered by the pressing force of the spring 23 in response to this, and the descending speed at this time is detected by the speedometer 24, and at the same time the weight 20 is used. The impact load is detected by the load detector 16, these detected values are added to the measurement value processor 26, and the ground amount is calculated from the deflection amount obtained by converting from the speed obtained from the speedometer 24 and the impact load.
Will be counted.

A bearing force test of the pavement 1a in the ground 1 is performed by the ground bearing force test apparatus of the present invention as shown in FIG. 2. In the case of the bearing force test of the roadbed 1b, the loading plate 14 is mounted on the pavement 1a. For example, a larger hole 27a having a diameter of 100 mm is opened and the loading plate 14 is directly placed on the roadbed 1b as shown in FIG. 3. Similarly, in the case of the bearing force test of the roadbed 1c, the hole 27b is further formed in the roadbed 1b. Then, the loading plate 14 is directly placed on the roadbed 1c as shown in FIG.

FIG. 5 shows another embodiment of the present invention. In this embodiment, a displacement detector 28 is placed on the ground 1 at a portion separated from the loading plate 14 by, for example, about 300 mm, and the displacement detector 28 is placed. Is supported by a spring plate 29 extending from the casing 17 of the ground supporting force testing device.

According to this embodiment, the amount of deflection of the ground 1 can be known more accurately, and the accuracy of bearing capacity evaluation can be improved.

[0027]

The effects of the ground bearing capacity testing apparatus of the present invention are listed below.

1. There is no need to provide a fixed point as in conventional devices, and no time is required to prepare for the test.

2. Since the device can be made small and lightweight, it is easy to carry when moving.

3. Since the method of dropping the weight is adopted,
A large impact load of 20 to 800 kgf can be obtained using a 20 kg weight.

4. Since the speedometer is used as the deflection (displacement) detector, the deflection of the ground can be measured simply by pressing the lower end of the deflection detection rod 22 against the ground.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional front view of a ground support force testing device of the present invention.

FIG. 2 is an explanatory view of a usage state of the ground supporting force testing device of the present invention.

FIG. 3 is an explanatory view of a usage state of the ground supporting force testing device of the present invention.

FIG. 4 is an explanatory view of a usage state of the ground supporting force test device of the present invention.

FIG. 5 is an explanatory diagram of another embodiment of the ground supporting force test apparatus of the present invention.

FIG. 6 is an explanatory view of a conventional ground supporting force testing device.

FIG. 7 is an explanatory diagram of a conventional ground supporting force testing device.

FIG. 8 is an explanatory diagram of a conventional ground supporting force testing device.

[Explanation of symbols]

 1 Ground 1a Pavement 1b Roadbed 1c Roadbed 2 Penetration piston 3 Load meter 4 Screw jack 5 Ball seat 6 Reaction force load device 7 Fixed point 8 Dial gauge 9 Track 10 Benkelman beam 11 Loading plate 12 Jack 13 Rubber plate 14 Loading Plate 15 Hole 16 Load Detector 17 Housing 18 Buffer 19 Drop Height Adjustment Mechanism 20 Weight 21 Guide Pillar 22 Deflection Detection Rod 23 Pressing Spring 24 Speedometer 25 Handle 26 Measurement Value Processor 27a Hole 27b Hole 28 Displacement Detection Container 29 spring plate

Claims (1)

[Claims] 1. A loading plate having a through hole in a central portion and placed on the ground, a load detector housing mounted on the loading plate, and a weight dropped on the housing. A hoe, a drop height adjusting mechanism for this weight, a ground deflection detecting rod supported by the casing so that its lower end is in contact with the ground through the through hole of the packing plate described above, and this deflection detecting rod. A ground supporting force testing apparatus, which counts the supporting force of the ground from a speedometer for detecting the descending speed of the ground, an impact load obtained from the load detector, and a deflection amount obtained from the speedometer.