Study on the effects of gasoil on shear behavior of coarse grained soils

Nowadays, change in geotechnical properties of the soil by oil pollution is one of the challenges of geotechnic engineers. In this study, thre effect of gas-oil pollution on shear strength parameters and shear behavior of the grawelly soil will be studied with a series of large scale direct shear tests. So large scale direct shear test (with box size of 30cm×30cm) is performed in well graded clayey grawel and pollution percent of 0, 3, 6, 9 and 12 with two level of normal stress (presentative of the low and high depth) and two compaction state.
The results show that the friction angel increases with increasing pollution fistly, then remains in constant amount for the soil with less compaction (unit weight of 17 KN/m3). While for the soil with more compacted (unit weight of 19 KN/m3), it is constant at first, then decreases and finally remains in constant amount. Also increasing more than 9% in pollution has no effect on friction angel. Soil cohesion increases firstly and then remains in constant amount with increasing pollution for both of compaction state. Also despite changing dilation angel with pollution percent, general expansion and contraction behavior of the soil remains costant for both compaction states and different levels of normal stress.