SU70564A1 - Device for determining and recording changes in soil compression properties - Google Patents

Description

Devices are known for testing the compressive properties of soil samples compressed under the action of centrifugal forces developed by a centrifuge, with simultaneous recording of the strain values of the test samples in which the carriages with the test soil samples are hinged to the rotating body of the centrifuge, but increase as the angular velocity rises. sideways, moving in radial planes.

The main disadvantage of such devices is the complexity of the design of the centrifuges and the difficulty of recording and recording the strain values of the tested soil samples.

In the described device, this disadvantage is eliminated; To do this, four simultaneously tested soil samples are placed in piston cylinders located at the four ends of the cruciform centrifuge housing, which is rotated around a vertical axis from the electric motor.

Loading of the samples under test with a compressing force is carried out by means of kinematically coupled cargo levers with moving loads moving along the levers as the centrifuge rotates, which allows the applied pressure to be adjusted in the range from 0.5 to 8 kg / cm.

Simultaneous recording of the compression curves and lateral pressure graphs for all four test soil samples is carried out by a recording device on the tape of one diagram drum. The mechanism of the recording device is similar to the principle of the manometer.

The schematic drawing shows a general view of the device in its vertical section.

The device is made in the form of a vertical centrifuge mounted on a concrete foundation; the housing / cruciform design is driven in rotation by a drive from the electric motor 2 via the coupling 3 and a pair of shchetereok 4. The centrifuge is stopped by means of a band brake 5.

70564-2. In the rotating case of the centrifuge four cylinders 6 are installed to place the test samples 7 of soil in them, which are compressed during the rotation of the case by the pistons 8 under the action of centrifugal force. The pistons are driven by kinematically associated cargo arms 9, along which the moving cargo 10 is moved along the rotation of the centrifuge casing 10 moving the goods by some distance along the lever changes the ratio of the arms of the lever .

The counterweight 11 is designed to balance the centrifugal forces of the cargo arm and the piston.

The change in the magnitude of the load is carried out by means of a gear wheel 12, kinematically connected with a lift 13 carrying mobile loads} 0. The counterweight M serves to balance mobile loads, the dead weight of the lift and its mechanism. The handle / 5 is used to fix the elevator during the test.

The deformation of the test samples of the soil is recorded and recorded as compression curves with a diagram pen 16 on a tape of a rotating diagram drum 17, which is placed in the center of the centrifuge body and is also rotated by a differential mechanism, parts of which are gear 18 and coupling 19.

Indicator arrow 20 serves to determine the end time of the testing process. The observation of the arrow is based on a stroboscopic effect and is made through a slit cut in the scraper 2 /. The initial position of the mechanism of the recording device is established by means of the adjusting screw 22.

The linear movement from the pistons 8 to the chart strings 16 is transmitted via flexible rods (belts) 23 and 24 and an intermediate roller 25 by means of a Watt mechanism consisting of three base links.

The lateral pressure drum on the test soil samples is recorded on the tape by means of split elastic rings in which the test soil samples are placed. The lateral pressure force is sensed by the prism 26 and transmitted to lever 27. This lever with a short arm rests on the split ring; on its long shoulder through a flexible cable (tape) 25, tongue 29 and lever 36, a spring is enclosed in housing 31. The purpose of the spring is to balance the lateral pressure.

An increase in lateral pressure on the test sample causes the lever 30 to move and the spring to compress until a new equilibrium state is established.

Accordingly, the movement of the lever 30 also moves the mechanism of the recording device, similar to the device for recording compression curves.

Subject invention

Claims (4)

1. A device for detecting and recording changes in the compression properties of a soil using a centrifuge designed to carry out the load and to rotate a sample of the soil enclosed in a cylindrical cup, equipped with pressure-generating material. characterized in that, in order to create during rotation of the system of mechanical load on the soil sample, a load lever connected to the piston rod is used, on prisms and provided with a load moving under the action of centrifugal force along the lever to create pressure on the sample located above. 2. The form of execution of the device according to claim 1. that the drive bar is connected with the recording mechanism feather through an intermediate lever under the influence of a spring, designed to create a pre-pressure on the sample and located in the direction of the centrifugal force developed by the centrifuge so that when the normal speed of the latter is reached, the spring action ceases as a result pushing it with the centrifugal force of a finger, in order to ensure uninterrupted contact of the test specimen with the sample under test at fixed centrifuges e. 3. The form of the device according to claim 1. characterized in that, in order to record the deformations of the sample in a direction perpendicular to the action of centrifugal force, the soil is placed in a sample of the soil and is provided with a longitudinal slit so that, depending on compression of the sample was an increase in the diameter of the beaker, transferred to the pen of the recording mechanism. 4. The form of the device according to claim 1, characterized in that, in order to record the deformations of the sample during the centrifugation process, the chart drum is fixed on the centrifuge's rotating axis and provided with a device for its additional rotation relative to the recording mechanism pen. No. 70564