一、 Summary

The dynamic triaxial test instrument is developed from the static triaxial test. By applying simulated active stress to the sample, it studies whether the vibration force of the foundation will be damaged by the objects in nature, such as earthquake, wave impact, mechanical vibration, explosion and high-speed motion. At the same time, the dynamic response of the sample under dynamic load was measured. This reaction is multi-dimensional, and the basic and main ones are the relationship between the dynamic stress (or dynamic principal stress) and the corresponding dynamic strain (σd-εd or σ1/σ3-εd), and the relationship between the dynamic stress and the corresponding void water pressure. According to the stress, strain and pore pressure of the three indicators of the relative relations, can be calculated from the dynamic elastic modulus, dynamic deformation modulus and damping ratio, for structure dynamic analysis of soil, at the same time and unearthed dynamic strength including liquefaction index, the strength of liquefaction, and analysis in the fields and dynamic action of soil structure stability and the dynamic elastic parameters and viscoelastic parameters, And the behavior of soil samples under the action of dynamic stress simulating some actual vibration.

   Tt.izzd-1 type intelligent dynamic triaxial test instrument is a set of high-end research and test of soil dynamic characteristics of laboratory equipment, mainly used for the strain of 10-4~10-2 sand liquefaction test, soil dynamic strength test, modulus damping test. Determination of dynamic stress, dynamic strain, pore water pressure, dynamic elastic modulus, dynamic damping ratio and other relevant data during the test process. With dynamic and static axial stress, lateral pressure and pore water pressure, axial loading program and other control functions.

二、 Main features

High precision motor control	It can realize static triaxial test with small strain and dynamic triaxial test with large strain.
Can be run offline	The instrument has built-in data storage system, which can upload data from the instrument to the computer for storage and processing.
Accurate test data	The system is a low friction dynamic triaxial apparatus. The load sensor is placed in the pressure chamber and directly contacts with the soil sample to reduce the error of friction and external factors on the test results and ensure the accuracy of the test results.
Replaceable load sensor	According to user requirements, different ranges (3KN, 10KN, 30KN, etc.) can be selected to achieve soil tests with different degrees of hardness.
High precision proportional valve	It can control the stable accuracy of confining pressure up to 0.1kpa.
Replaceable base and sample cap	Soil samples of different diameters (39.1mm, 61.8mm, etc., can also be customized) can be tested in the same chamber.
Stress strain dual control mode	The dynamic test of strain control and stress control can be realized.

三、 Possible tests

Consolidation drained triaxial test (CD), consolidation undrained triaxial test (CU), consolidation undrained triaxial test (UU), stress or strain controlled dynamic loading test, soil permeability test.

四、 Upgrade options

Bending element test, Hall effect local strain sensor, LVDT local strain sensor, unsaturated soil test, temperature control test.

五、 Main technical parameters

六、 System composition configuration and options

☆ Data acquisition and digital control system
The system uses a 32-bit high-speed ARM processor and a digital circuit to control the displacement and load. Equipped with 24-bit data acquisition (A/D); Equipped with high precision proportional valve, stable control of confining pressure; Equipped with 800x600 LCD touch screen, display the test indicators; Equipped with high-speed RJ45 network port, realize communication with computer software;

☆ High precision servo motor loading system
Servo point motor is used to control loading and loading system, which can achieve high precision control of axial displacement and pressure. The system is an important part of dynamic triaxial experiment, which not only exerts consolidation pressure on the sample, but also exerts dynamic displacement on the soil sample. It applies axial load to pressure chamber by servo control system and precise ball screw propulsion loading platform, and can carry out stress and strain triaxial test controlled by open loop and closed loop. The static loading rate of the system (0.001~30 mm/min) is composed of servo motor, driver, single-chip microcomputer control system and load sensor. Under the condition of dynamic loading, the triaxial experiment of multistage strain control is carried out by the dynamic displacement setting controlled by single chip microcomputer.

☆ High precision pressure/volume controller (larger range can be customized on demand)
Equipped with a set of 2MPa/250cc pressure/volume controller, used to control the back pressure control and displacement measurement, can achieve constant current and constant pressure two loading modes; Built-in overload and overvoltage protection device, pressure measurement accuracy is 0.1% of the full range, resolution is 0.1kpa, volume measurement accuracy is 0.1% of the full range, resolution is 0.01mL

☆ Underwater load sensor
Built-in 4KN underwater load sensor, pressure ≤7Mpa, accuracy is 0.1% of full scale, resolution 0.1N

☆ Computer data acquisition and processing software
A set of control, acquisition, processing in one of the software platform, using network communication, real-time control of the test; It has the function of data collection and can run offline. The data can be read by the instrument after the test is completed. Specific data processing functions, drawing Moore envelope line, calculating C, φ, drawing hysteresis loop and so on.

☆ Dynamic triaxial tester pressure chamber
The pressure chamber of the dynamic triaxial tester is the main core part of the test, which is composed of soil sample, soil sample base, soil sample cap, and the latex film wrapped in the soil sample outside; The pressure outer shell is made up of high pressure resistant plexiglass cylinder, aluminum alloy base, top cover, pressure transmission piston, piston sleeve, confining pressure proportional valve loading system and the pressure chamber is equipped with pore pressure sensor, back pressure, air inlet and drainage, pore pressure and other pipelines, as well as various sensor cable fastener interfaces and valves.

☆ Confining pressure control device
Under normal circumstances, the confining pressure is controlled by hydraulic pressure, but due to the vibration of the confining pressure fluctuations, the device is currently controlled by air pressure. Air pressure control is provided by an inlet proportional valve to provide a stable air pressure source. Pressure range: 0~900Kpa This method is convenient to operate. If necessary, water can be added to the top drainage position in the pressure chamber, and then air pressure control.

☆ Backpressure volume change and pore pressure measurement system
The application of back pressure is mainly to solve the problem of soil sample saturation, of course, there are many methods to solve the saturation: vacuum air saturation, head saturation, back pressure saturation and other methods. For general clay permeability coefficient: Larger than N *10-7cm/s, the back pressure volumetric change system, that is, the hydraulic controller, can be used to compress the air bubbles in the soil and improve its saturation. However, in this system, we can apply back pressure to one end of the soil sample and let it drain water at the other end of the soil sample, so that the air bubbles in the soil sample can be eliminated under the action of circulating water and the volume change can be measured. The measurement of pore pressure is stored by the digital quantity of the pore pressure sensor or directly input into the computer.