Device for centrifuge testing of driven pile in different installation and pull-out modes and operation method therefor

A device for centrifuge testing of a driven pile in different installation and pull-out modes, comprising a supporting system, a pile driving system, a pile-soil system and a measurement and acquisition system, wherein

• the supporting system comprises a vertical supporting system and a pile driving frame supporting system;
• the vertical supporting system comprises a threaded rigid column, a vertical outer support frame, a vertical inner support frame and a bottom rigid plate;
• the vertical supporting system is configured to support an entire test model and connected to a corresponding device of the centrifuge, and at the same time provides a supporting platform for a pile driving frame in the model;
• the vertical outer support frame is movably connected to the threaded rigid column, and is controlled to lift by a vertical support lifting motor;
• the pile driving frame supporting system is configured to support the pile driving frame and comprises an upper pile driving frame outer support, an upper pile driving frame inner support, a lower pile driving frame inner support, a lower pile driving frame outer support, an upper pile driving frame back support and a lower pile driving frame back support, and the pile driving frame supporting system ensures that the pile driving frame is kept stable in a pile driving process and a geotechnical centrifuge test process;
• the pile-soil system comprises a model pile and a model box, a pile cap is fixed at the top of the model pile and protects a pile head of the model pile in a penetration process, an element for monitoring physical and mechanical variables is attached to a pile body, the model box is a semi-cylindrical box body with a closed lower portion and an open upper portion, a semicircular portion is composed of high-strength and high-rigidity steel plates, drain holes are distributed in the box body, a semicircular section of the model box is composed of transparent plates made of a high-strength resin, soil is arranged in the model box, and a lifting motor is arranged below a fixing support and sleeves the threaded rigid column;
• and the lifting motor drives a nut to rotate to lift on the threaded rigid column, so as to control a height of the fixing support;
• a centrifuge system comprises a centrifuge, the supporting system, a full-life loading system of a driven pile and the pile-soil system are fixedly installed in a test cabin of the centrifuge, supergravity is applied to the test model through movement of the centrifuge, and a time of fluid-solid coupling is shortened in a supergravity environment to speed up a change process;
• and
• a measurement system comprises a soil monitoring system and a pile body monitoring system, the soil monitoring system comprises a soil monitoring element, the pile body monitoring system comprises a pile body monitoring element, the soil monitoring element tests an initial stress-strain of a soil sample, a pore pressure state and corresponding physical and mechanical parameters during pile driving and after installation, and the pile body monitoring element is capable of acquiring physical and mechanical parameters such as pile body deformation stress;
• wherein the pile driving system comprises a pile driving frame, a pile driving device and a penetration and pull-out power device;
• the pile driving frame is connected to the vertical supporting system through the pile driving frame supporting system, and the pile driving device comprises a pile hammer guide rail, a guide rail for a driven pile and a penetration and pull-out power device;
• the penetration and pull-out power device is provided with a power system and a pile hammer, and a pile hammer pad is installed on a lower portion of the pile hammer;
• a pull-out mode is vibration pull-out or static load pull-out, a lower end of a pull-out device is provided with a hammer pad, the hammer pad conducts electricity to generate electromagnetic attraction, and a magnetic force of the hammer pad is controlled by changing a current;
• the pile cap is made of a magnetically attractable material, the hammer pad is magnetically attracted to the pile cap after being energized, and the pile cap, the hammer pad and the model pile are fixed to be a whole in the pull-out process.