RU2510440C2 - Device for complex determination of physical and mechanical properties of soils under field conditions - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: device for complex determination of physical and mechanical properties of soils under field conditions includes an anchor, a thrust beam, a load screw, a turning wheel, an impeller and a cutting ring. In order to enlarge functional capabilities and improve measurement accuracy, it is equipped with a servo drive with a screw, which is installed on the thrust beam, a torque sensor fixed on a tie rod with a circular die, a force sensor fixed in lower part of the servo drive, a vertical movement sensor installed at a reference point. The servo drive, the force sensor, the torque sensor, the vertical movement sensor are connected to the control unit and through an interface to a computer, thus forming a measurement system with direct and feedback communication between the sensors and the servo drive.

EFFECT: improving accuracy of loading and measurement by automatic control of performed tests.

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Description

Technical field

Determination of the mechanical properties of soils in the field during engineering and geological surveys and soil surveys in the basis of existing foundations.

State of the art

An analogue of the claimed technical solution is the "Installation for testing rocky and semi-rocky soils completely ring using an anchor" (P-43-89. Recommendations for determining the characteristics of the rheological properties of rocky and semi-rocky soils by ring loading. L., VNIIG them. B.E. Vedeneeva, 1990, Fig. 4, 6, pp. 16-17 [L1]), including anchor, thrust frame, embedded I-beam, hydraulic jacks, concrete stops, ring pillar, dial indicators.

The disadvantage of this analogue is that this device is cumbersome, since it is proposed to be used for field tests of rocky and semi-rocky soils with an annular whole diameter of 1 m. To create a tangent load, an embedded I-beam and two hydraulic jacks are used, and the beam itself is located in a pre-drilled cavity through the annular pillar, while the jacks should abut against concrete stops. A similar shear loading scheme is not possible in clay and sandy soils due to their low strength and high compressibility.

The next analogue of the claimed technical solution is the "Method of soil testing" (USSR copyright certificate SU 657315 A1, application 2362128 / 25-28 of 05.17.1976, IPC ⁵ G01N 3/08, G01N 3/22, applicant of the Order of the Red Banner of Labor VV Kuibyshev Construction Institute, author V.L. Kubetskiy, published on 04.15.1979 [L2]), which consists in the fact that an annular stamp is placed on the ground, compressive and torque forces are created, they are measured and judged by the data obtained about the properties of the soil, characterized in that in order to improve accuracy during testing and rocky soil use a stamp with smooth transitions to the soil, which is rigidly fastened to the latter.

The method is as follows.

An annular stamp with smooth transitions to the ground is installed on the ground, and it is firmly fastened to the ground, for example, the stamp used is made directly from the concrete. The stamp provides for stresses, for example, with a jack, and a platform.

Then, using a system of loaders, for example, jacks, a compressive force is created on the ground, and a torque force is created by acting on the stops in such a way that the line of action of the force is parallel to the tangent to the surface of the stamp. The forces acting on the soil are measured, and the properties of the soil are judged by the data obtained. This method allows us to judge not only the strength of the surface layers, but also the strength of the deep layers of the soil, which increases the accuracy of determining the properties of the soil as a whole.

The disadvantage of this analogue is that it lacks the possibility of testing with the control of the system of the loaders, which does not allow testing with continuous loading at a given strain rate. The second disadvantage is the lack of a system for automated recording of measurement data of compressive and torsional forces during testing, which reduces the accuracy and performance of the tests.

The closest analogue (prototype) of the proposed technical solution is UNIVERSAL INSTALLATION VSEGINGEO (Handbook of Engineering Geology, 3rd edition, revised and supplemented, under the editorship of M.V. Churinov, M., Nedra, 1981, Fig. 71, p. 300 [L3]), comprising an anchor post, a support beam, a load screw, a dynamometer, a rotary lever with a dynamometer, a rotary ring, an impeller or a cutting ring, an outrigger.

The installation is designed to determine the strength parameters of sandy clay and clayey-gravelly soils on the surface and in pits by circular cutting of rocks along a round-cylindrical surface, as well as for cutting large cylindrical specimens from an array into a ring ring.

The disadvantage of the prototype is the inability to create large vertical movements of the rotary ring, the impeller or the cutting ring due to the restrictions imposed by the design of the cantilever thrust beam. The second disadvantage is that the vertical load is created by a hydraulic jack, which necessitates constant monitoring of the pressure in the hydraulic cylinder due to its fall due to the upsetting of the rotary ring, which is difficult to perform in manual mode of loading control. A significant drawback is that the measurement of vertical displacement, load and torque is performed manually, which reduces the performance and accuracy of the tests. Another disadvantage of the prototype is that during the test process, only two strength characteristics of the soil are determined - the angle of internal friction and the specific adhesion force, while there is a need to determine the deformability characteristics.

The essence of the technical solution

A device for testing soils in the field, including an anchor, a thrust beam, a loading screw, a rotary ring, an impeller and a cutting ring for testing soils in the field.

The purpose of the invention is the expansion of functionality, improving the accuracy of loading and measurements by automatically monitoring the tests.

This goal is achieved by the fact that a servo motor is used to create a vertical load, and the creation and regulation of the vertical load application speed is controlled by a computer through a control unit for force and displacement sensors.

To perceive the reaction from the vertical load, two anchors and a folding beam are used.

To increase the accuracy of creating a tangential load, torque measurement is performed using the console and the force sensor.

An accelerometer is introduced into the anchor to measure the shear wave velocity.

To expand the functionality, round and screw dies, a probe are introduced into the device, which allows you to determine additional mechanical characteristics of soils, such as elasticity and deformation modulus, shear modulus. In this case, the determination of soil deformability parameters will be carried out in accordance with applicable GOST.

List of figures, drawings and other materials

Figure 1 shows a General view of the design of the device for the integrated determination of the physical and mechanical properties of soils in the field.

Figure 2 shows a block diagram of the measurements.

Figure 3 shows the design of a collapsible thrust beam.

Figure 4 shows the design of axial loading.

Figure 5 shows the design of an annular stamp with a torque sensor.

An example of the implementation of the proposed technical solution

In figure 1, 2, 3, 4, 5, the device contains two screw anchors 1, a folding stop beam 2, on which a servo-drive 3 is fixed with a screw 4, a force sensor 5 is fixed on the lower part. A torque measuring sensor 6 is connected by means of rods 7 with a ring stamp 8. The device contains a set of interchangeable devices: ring stamp 8, round stamp 9, screw stamp 10, penetrometer 11, probe 12, impeller 13, sampler 15.

In the lower part inside the anchor 1 there is a three-axis accelerometer 16, a unit for amplifying and converting signals to digital form 17, which is connected wirelessly or wired to the control unit 18 and through the interface 19 to the computer 20.

On the upper part of the rod of the round stamp 9, a movable console 21 is fixed, on which the rod of the vertical displacement sensor 22 is supported, mounted on the holder 23 and the reference 24. The displacement sensor 22 is connected wirelessly or wired to the control unit 18.

A torque sensor 6 with handles 25 is mounted on one of the rods 7 and is connected wirelessly or wired to the control unit 18 and through the interface 19 to the computer 20.

In the upper part of the screw anchor 1 there is a gripper 26 for connection with the thrust beam 2.

The stop beam 2 consists of two collapsible pipes 27, at the ends of which there are support strips 28, which serve as a stop for installation in the gripper 26. The holder 29 is designed to install a servo drive 3 with a screw 4, as well as to fix the folding pipes 27 of the stop beam 2 on it. In the working position of the beam 2, the folding pipes 27 are interconnected by a locking pin 30. On the frame 24 there is a holder 32 for installing the displacement sensor 33.

The torque sensor 6 has a force sensor 34 and a console 35, which is mounted on one of the handles 25.

The device operates as follows.

Stage 1. Preparation of the device for testing

1. On the soil surface, the bottom of the pit or pit, using a servo drive 3 with screw 4, two screw anchors 1 are wrapped in soil at a distance equal to the distance between the slats 28 on the stop beam 2.

2. The thrust beam 2 is fixed with screws 31 in the grippers 26 on the anchors 1.

3. The servo drive 3 is fixed on the holder 29 in the Central part on the thrust beam 2 and connected to the control unit 18.

4. A reference point 24 is installed on the surface of the soil and holders 23, 32 of displacement sensors 22, 33 are attached to it. The displacement sensor rod 33 is installed anywhere on the surface of the stop beam 2. The displacement sensors are connected to the control unit 18.

The readings of the displacement sensor 33 make it possible to evaluate the deflection of the thrust beam 2, which is taken into account when measuring the vertical displacement of a particular device.

5. Force sensors 5, 34, displacement sensors 22, 33 are connected to the control unit 18.

6. The control unit 18 through the interface 19 is connected to the computer 20.

Stage 2. Implementation of the automatic test method and test sequence

1. Choose the type of device for soil testing: round stamp 9, screw stamp 10, penetrometer 11, probe 12, impeller 13, ring stamp 8 or sampler 15.

2.1. Tests with a round stamp of 600 cm ²

2.1.1. A round stamp is installed on the soil surface coaxially with the screw 4 and, using the holder 23, fix the displacement sensor 22 so that its rod abuts against the movable console 21.

2.1.2. Using the method of GOST 20276-99 section 5 [L4], a stamp test is performed. The stamp draft measurement and load control are performed automatically using the readings of the displacement sensor 22, the force sensor 5 and the servo drive 3. The measurement data are entered into the computer base.

2.1.3. Using the measurement results under paragraph 5.5.2 of GOST 20276-99, find the module of soil deformation.

2.2. Tests with a 600 cm ² screw die

2.2.1. A screw stamp is mounted on the soil surface coaxially with the screw 4 and, using the holder 23, fix the displacement sensor 22 so that its rod abuts against the movable console 21.

2.2.2. Using the methodology of GOST 20276-99 Section 5, a stamp test is performed. Screwing the stamp into the ground and applying a vertical load is performed using a servo drive 3. Measurement of the draft of the stamp and load control are performed automatically using the readings of the displacement sensor 22, force sensor 5 and servo drive 3. The measurement data are entered into the computer base.

2.2.3. Using the measurement results under paragraph 5.5.2 of GOST 20276-99, find the module of soil deformation.

2.3. Ring Stamp Tests

2.3.1. An annular stamp 8 is connected to the rod 7, and it with a torque sensor 6, after which it is installed coaxially with the screw 4 under the thrust beam 2.

2.3.2. Using the method of ring cut GOST 20276-99 section 12.4, carry out tests by the method of ring cut. Monitoring and control of normal pressure is carried out automatically using the sensor 5 and servo drive 3. Measurement of the tangential load is performed automatically using the torque sensor 6, and the application of the load manually using the knobs 25. The measurement data is entered into the computer database.

2.3.3. Using the measurement results under paragraph 12.4.4 of GOST 20276-99, find the strength characteristics of soils: the angle of internal friction and the specific adhesion force.

2.4. Probe test

2.4.1. Using the method of static sensing GOST 19912-2001 section 5 [L5], conduct tests using the proposed device. The continuous loading speed is created by a servo drive 3 and controlled by a computer 20. The probe immersion speed is measured by a displacement sensor 22, and signals from the probe sensors are transmitted through the control unit 18 to the base of the computer 20.

2.4.2. Using the results of measurements according to paragraph 5.5 of GOST 19912-2001, indicators of soil resistance to penetration of the probe are found.

2.5. Tests to determine the elastic shear modulus

2.5.1. To determine the elastic shear modulus, an impact is created on the soil surface, for example, with a hammer weighing 8-12 kg on a metal plate 14, the transverse wave arising from this is recorded by an accelerometer 16.

2.5.2. Using the measured value of the shear wave velocity (V _s ), find the value of the elastic shear modulus:

,

,

where ρ is the density of the soil.

3. Impeller tests

Stage 1. Preparation of the device for testing.

1. The impeller 13 is connected to the rod 7, and it is with a torque sensor 6. The force sensor 34 is connected to the control unit 18.

The impeller 13 is connected to a torque sensor.

Stage 2. Test sequence

2.1. Using the rotational cut method GOST 20276-99 section 12.2, impeller tests are carried out. The measurement of the tangential load is carried out automatically using the torque sensor 6, and the application of the load manually using the knobs 25.

2.2. Using the measurement results under paragraph 12.2.4 of GOST 20276-99, find the specific adhesion of clay soils.

4. For sampling soil, for example, a thin-walled sampler 15 is used, which, using a set of rods 7, is continuously pressed into the soil using a servo drive 3.

Industrial applicability

This device for the comprehensive determination of the physical and mechanical properties of soils in the field is industrially feasible, has wider functionality, increased accuracy in determining the parameters of soils.

Literature

1. Recommendations for determining the characteristics of the rheological properties of rocky and semi-rock soils by the ring loading method. L., VNIIG them. B.E. Vedeneeva, 1990, Fig. 4, 6, pp. 16-17.

2. USSR author's certificate No. 657315 A1, application 2362128 / 25-28 dated 05/17/1976, IPC ⁵ G01N 3/08, G01N 3/22, applicant of the Moscow Order of the Red Banner of Labor; V.V. Kuibyshev. The method of testing soils, author V.L. Kubetskiy, published April 15, 1979.

3. Handbook of Engineering Geology, 3rd edition, revised and supplemented, ed. M.V. Churinova, M., Nedra, 1981, fig. 71, p. 300.

4. GOST 20276-99. Soils. Field methods for characterizing strength and deformability. M., 1999 .-- 91 s.

5. GOST 19912-2001. Soils. Field test methods by static and dynamic sounding. M., 2001 .-- 27 p.

Claims (5)

1. A device for the comprehensive determination of the physical and mechanical properties of soils in the field, containing an anchor, a thrust beam, a loading screw, a rotary ring, an impeller and a cutting ring, characterized in that, in order to expand the functionality and improve the accuracy of measurements, it is equipped with: a servo drive with a screw mounted on the stop beam, a torque sensor mounted on a rod with an annular stamp, a force sensor fixed to the bottom of the servo, a vertical displacement sensor, mounted on a benchmark, a servo drive, a force sensor, a torque sensor, a vertical displacement sensor are connected to the control unit and through an interface to a computer, forming a measuring system with direct and feedback between the sensors and the servo drive. 2. A device for the comprehensive determination of the physical and mechanical properties of soils in the field according to claim 1, characterized in that the torque sensor has a force sensor and a console. 3. A device for the comprehensive determination of the physical and mechanical properties of soils in the field according to claim 1, characterized in that the anchor has a three-axis accelerometer built in it and a unit for amplifying and converting signals to digital form. 4. A device for the comprehensive determination of the physical and mechanical properties of soils in the field according to claim 1, characterized in that the thrust beam is folding. 5. A device for the comprehensive determination of the physical and mechanical properties of soils in the field according to claim 1, characterized in that the tests are performed automatically under computer control.

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