Abstract: According to the need of laboratory study of the generalized stress relaxation characteristics of rock, an experimental system of uniaxial tension servo control, which is based on stress feedback take hardware devices as basis and transforms data recording and servo controlling to achieve the stress feedback method, is developed. The advantages of the uniaxial tensile test system are as follows: (1) The system can realize the stress feedback, except carry out the traditional displacement control and stress control of the load alone, also stress-strain linear combination of servo control. (2) The measurement system and control system are realized by hardware rather than computer software; the structure is simple and compact; the reaction time of the system action is short; the performance is stable and reliable; the space of upgrading is large. (3) The control and monitoring data use simulate signal transmission and the test process control and data acquisition accuracy are higher. (4) By using high strength adhesive, the specimen is in the state of tension; and the stress state of rock mass can be simulated in real engineering. Using this system, the generalized relaxation test of tage tuff under tensile stress has been accomplished, and the test results show that the device has good practicability and reliability, so as to provide a new method and means for studying the mechanical properties of generalized stress relaxation under the action of tensile stress of rock in engineering practice.

Key words: direct tension, testing system, stress feedback control, generalized stress relaxation