Investigation of Liquefaction of Silty Sandy Soils Using Cyclic Triaxial Stress Test

Abstract

The history of previous earthquakes demonstrates that the liquefaction phenomenon significantly impacted damage. The impact of factors like cyclic stress ratio and percentage of non-paste fine grain in constant all-round pressure on the liquefaction potential of silty sand was investigated in the current study using a periodic triaxial test. The sand and silt near the Euphrates River in Al-Ammari village have been used in this regard. Four types of soil were studied, each with a different amount of sand and silt, including pure sand without silt, 75% sand and 25% silt, 50% sand and 50% silt, and pure silt without sand. In the following this samples were consolidated according to the 100 kPa all-round pressure, and the triaxial periodic consolidated undrained (CU) test was performed. The intermittent tension control loading operates in three different CSR modes, including 0.1, 0.15, and 0.2. The results show that the soils containing 25% and 50% silt have a higher and lower liquefaction potential than the other investigated samples. Also, results show that when CSR=0.2, liquefaction occurs faster and with fewer cycles, whereas CSR=0.1 liquefaction occurs later and requires more cycles. The soil sample containing 50% silt reached liquefaction sooner than the other soils at CSR=0.1 but later at CSR=0.2. The soil containing 25% silt liquefied faster than the rest at CSR=0.2. Finally, it can be concluded that soil behavior characteristics such as liquefaction are heavily influenced by the composition of different soil types, applied pressure, the presence of cyclic load, and so on; therefore, investigation of various situations is critical.