RU224913U1 - Digital penetrometer for measuring compressive and tensile forces - Google Patents

Abstract

The utility model relates to devices designed to determine the strength characteristics of soil using the penetration method, as well as to determine the parameters of soil shear resistance. Digital penetrometer for measuring compressive and tensile forces, including a rigid cylindrical column fixed on a rigid base, with the ability to change the angle of fixation, inside which there is a movable probe with replaceable tips. In this case, the probe is connected to handles to exert pressure on the ground through a strain gauge capable of working in both compression and tension. The technical result consists in expanding the functionality of the device, as a result of which there is an increase in the accuracy of the data (correlation of the traction force exerted on the load with the stamp and the amount of displacement of the stamp relative to the test surface) due to the same errors (of the same sensor) in different test modes.

Description

The utility model refers to devices designed to determine the strength characteristics of soil using the penetration method, as well as to determine the parameters of soil shear resistance.

A device is known for studying the physical and mechanical properties of soils, which can be used in calculating the bearing capacity of foundations. The penetrometer consists of a body, a screw-on top cover, in the sleeve of which a rod with a washer on top moves, and handles are screwed into this washer from two opposite sides. The lower end of the rod is screwed into the piston, which transmits pressure to the dynamometer spring, which rests on the diaphragm, rigidly connected to the body of the device, below which there is a spring, which rests on the piston with a rod, and below the piston there is a spring, held from below by a lid. A conical tip screwed to the rod penetrates into the soil being tested under pressure. To measure, the device is placed in a vertical position and, after lightly touching the cone to the soil being tested, the handles are pressed, transmitting force to the rod, spring and diaphragm. Readings are obtained on the scale of the clamp, which records the degree of compression of the spring. The disadvantages of this known device include the fact that the readings may have a significant error due to the mechanical nature of their recording. It is impossible to determine the exact force when immersing the nozzle to different depths; it is impossible to record changes in this force (see patent SU 729511 A1 Published : 1980.04.25)

The closest to a utility model in terms of technical essence and the achieved technical result is a penetrometer, which has a plug-in microcomputer that reads the force on the rod using strain gauges (see patent CN107842010A Published : 2018.03.27). This device operates on a similar principle as the one described above - by applying pressure through the handles to the rod, which presses the nozzle into the ground, but has significantly greater measurement accuracy. The disadvantages of this known device include the fact that it cannot be used in soil tests where a tensile effect on strain gauge elements is necessary (for example, to determine the parameters of soil shear resistance).

The purpose of the utility model is to create a device capable of effectively determining the strength characteristics of soil using the penetration method, as well as determining the parameters of soil shear resistance. The technical result achieved in this case is the expansion of the functionality of the device, as a result of which there is an increase in the accuracy of the data (the correlation of the traction force exerted on the load with the stamp and the amount of displacement of the stamp relative to the test surface) due to the same errors (of the same sensor) in different test modes .

The technical result is achieved by the fact that in a digital penetrometer for measuring compressive and tensile forces, containing a cylindrical column, one end of which is attached to a rigid base, a movable probe with replaceable tips with handles for exerting pressure on the ground, a strain gauge capable of working both in compression is used , and tensile, for example, an S-shaped strain gauge.

The novelty lies in the use of a strain gauge capable of measuring both compressive and tensile forces, as well as in the design of the device, adapted for both test modes, which allows it to be used in studies where compressive and tensile forces are required. Also new is the conveniently disassembled design of the device, which allows it to be transported compactly; this same property ensures safety for electronic equipment, since it can be carried separately in better conditions, which are not required for ballast, rod and other elements. Another innovation is that at any moment in time the measurement is carried out, accurate recording and correlation of force and displacement readings is ensured in the modes of both compression - penetration mode, and tension - shear testing mode. To record the regime of penetration and shear tests, the device includes a camera capable of recording experimental conditions in both surface and submerged positions.

The utility model is illustrated by drawings, which show the following:

Fig. 1 – general view of the device for determining the strength characteristics of soil using the penetration method.

Fig. 2 – illustration of the use of a penetrometer when working in tension.

The lower end of the column 1, made in the form of a cylindrical pipe, is attached with the possibility of changing the angle of inclination relative to the base 2 and the possibility of setting this angle in a self-orienting mode. The rigid base serves as a stop for soil penetration.

The mounts of the probe 3 allow it to move freely along the cylindrical pipe 1 with minimal resistance during this kind of movement. In this case, the fastenings of the probe 3 ensure its alignment with the pipe with minimal errors. Thus, the cylindrical pipe 1 with a base serves as a guiding element during penetration.

The movable probe 3 is equipped with replaceable tips 4 with handles for exerting pressure on the ground.

A gear rack 8 is rigidly connected to column 1 in mesh with a gear connected to an incremental angular encoder LIR 158A. The encoder gear is rigidly connected to probe 3. Thus, when the probe moves, the gear “walks” along the rack. This mechanism allows you to accurately determine the depth of immersion of the probe into the ground at any time during the measurement.

To measure the force during penetration (compression) or to measure the force in soil shear testing (tension), an S-shaped tension-compression strain gauge C2H is used.

To record the regime of penetration and shear tests, the device includes a camera 7, capable of recording experimental conditions in both surface and submerged positions.

The encoder with its gear, sensor and penetrometer handles are combined into a removable block 9, which has a protective casing to prevent damage to the equipment. Removable block 9 is connected to probe 3 using a threaded connection.

From the encoder and sensor, the readings through a wired connection enter the electronic unit 5, where they are recorded on electronic media at each moment in time when the measurement is taken.

To study the parameters of soil shear resistance, a special platform 10 is attached to the penetrometer for basing the penetrometer, as well as a guide device 11 and a special ballast 6, which exerts a normal impact on the soil.

Measurements are made as follows: when penetrating soil, the penetrometer is installed vertically relative to its base 2. The required nozzle is screwed onto the end of the probe. Next, using the handles, the probe is pressed into the ground, while the above-described equipment registers and saves the obtained parameters.

When studying the parameters of soil shear resistance, the penetrometer is provided with the possibility of self-orientation of the angle relative to the base 2. The base itself is fixed on a special platform 10 for basing the penetrometer, which in turn is fixed to the ground with anchors. A steel cable 12 is attached to the end of the probe 3 and is guided through the guide device 11 to the ballast 6. Then, using human effort or using a winch, a tensile force (relative to the sensor) is applied until a certain movement of the ballast 6. The equipment registers and stores the obtained parameters.

Claims (2)

1. Digital penetrometer for measuring compressive and tensile forces, including a rigid cylindrical column fixed on a rigid base, with the ability to change the angle of fixation, inside which there is a movable probe with replaceable tips, characterized in that the probe is connected to handles to exert pressure on the ground through strain gauge capable of operating in both compression and tension. 2. Digital penetrometer for measuring compressive and tensile forces according to claim 1, characterized in that an S-shaped strain gauge is used.