Structural Design and Dynamic Simulation Optimization of the Triggering Device in a Pressure-Holding Controller for Deep in Situ Coring

As Earth's shallow coal resources are gradually depleted, humans turn their mining operations to deeper regions. However, because the mechanics of deep-rock masses have not been fully established, the development of deep resources lacks theoretical guidance, and the continuity of such engineering activities is poor. The basis of deep-rock mechanics theory is to achieve deep in situ rock fidelity coring (including the maintenance of pore pressure and temperature). To achieve this goal, deep in situ pressure-holding coring technology is needed. The pressure-holding controller is the key corer component for realizing deep in situ pressure-holding and coring technology. The flap-valve-type pressure-holding controller driven by an elastic force or gravity alone is not enough to provide the initial sealing pressure for the sealing surface. Therefore, a trigger mechanism that assists the pressure-holding controller in achieving closing and initial sealing was designed. Then, the action and friction characteristics of the triggering mechanism were calculated according to the experimental dynamics simulation calculations of different closing characteristics that are affected by gravity in pressure-holding controller space. Optimization was conducted to determine the optimal values of the trigger mechanism spring stiffness, wedge angle, and other parameters. The mechanism can provide technical support for deep pressure-holding coring and improve the pressure-holding power of deep in situ rock coring.