Triaxial tests research on strength properties of the polypropylene fiber reinforced soil

Conventional triaxial compression tests were carried in order to study the strength effect and mechanism on fiber reinforced soil of the length and content for polypropylene fiber, and different length of the polypropylene fiber (6mm, 12mm, 19mm) were added to the sand clay with the popropertion of 0.1%, 0.2%, 0.3%, 0.4% respectively according to the weight. It is concluded from tests that the strength and the overall stability of the polypropylene fiber soil increase obviously compared to plain soil. In addition, strength will improve with the increase of fiber contents firstly and then drop and it will give play to effect of the fiber reinforcement when the content is 0.3%. At the same time, the effect of the different fiber length isn´t identical even through the content is same. The main reason is that the joint action between occlusive friction and force of space constraint after the net structures are formed because of the bending fiber and uniformly soil.