ABSTRACT
Abstract: This paper intends to make a global and historical review of the development and application of rock true triaxial testing (TTT) systems. The TTT systems can generally be classified into three types, i.e., rigid loading type (Type-I), flexible loading type (Type-II) and mixed loading type (Type-III).Each type has their respective advantages and disadvantages in terms of loading capacity, the end friction effect, blank corner effect, experimental accuracy as well as the functional extendibility. Type-III has higher level of overall performance. Type-I appeared first and dominated in number at the early time. After 1980s, the number of Type-III true triaxial machine has steadily increased. Now, Type-I and Type-III machines are approximately the same in number. They are bothwidely been used in rockmechanics. The paper also focuses on the results obtained from Type-III regarding the influence of intermediate principal stress on strength, deformation characteristics, permeability change features, etc. In the end, comments and recommendations are made for the further development of TTT techniques.
