Development of a True Triaxial Apparatus for Sands and Gravels
A recently developed true triaxial apparatus and a series of verification studies are presented in this paper. The apparatus is capable of handling 241-mm cubical specimens providing the means for testing specimens under a wide variety of stress paths under drained and undrained conditions. It uses flexible boundaries to apply 3 independently controlled principal stresses with back pressure. The apparatus also uses a fully computer-controlled electro-pneumatic loading system with advanced technology for data control. A testing program is presented for the purpose of verification. Pea-gravel specimens with D-sub-50=6.6 mm were tested under fully stress-controlled loading conditions. The stress paths used in this verification study include undrained and drained constant total mean stress paths and conventional triaxial compression and extension stress paths. Results indicate the newly developed apparatus is capable of capturing the stress-strain characteristics of coarse-grained soils.
The article introduces the applications of model 3NB800,3NB1000 mud pump.Pertinent improvements are made,on which based the analysis for the cause of the low self absorption pressure.experiments with twenty eight improved pumps show that the technique is mature and effective.