Advantage and Limitations of direct shear test  ?

Advantage of direct shear test  

1. The direct shear test is a simple test and relatively fast especially for granular soils .
2. The basic principle is easily understood which can be extended to gravelly soils and other materials containing large particles. 
3. The apparatus is relatively cheap.
4. It is not difficult to prepare recompacted test samples. 

Limitations of direct shear test 

1. It is difficult to control the drainage conditions if an undrained test is conducted.
2. The stress conditions across the soil samples are very complex. 
3. The plane of shear failure is predetermined and may not necessarily be the weakest one.
4. There is an effect of lateral restraint by the side walls of the shear box.