In order to study the long-term THM coupled behaviour of soft rock

a parallel-linkage triaxial testing machine for THM coupling in soft rock is developed. This machine is particularly applicable to study the mechanical properties of soft rock under different temperatures and various stress conditions. Using the technology of servo-control

this machine can automatically stabilize voltage and record experimental data. It can also achieve temperature gradient loading

pore pressure gradient loading and independent stress gradient loading. Furthermore

high-precision LVDT sensor is also implemented to measure the deformation. This machine can complete these tests including uniaxial compression test

triaxial compression test

triaxial rheological test

cyclic loading and unloading test

penetration test under steady state and transient conditions. It can simultaneously implement the mechanical tests of two samples with the same confining pressure

the same pore water pressure

different axial pressures and different temperatures

thanks to the unique design of this machine. It can save time because of this feature

especially for the long-term mechanical test. In addition

it can also reduce the system errors. The results of these tests during last year show that this machine is a convenient machine with complete functions

good stability and high precision.