Liquefaction and Reliquefaction Characteristics of Cement Mixing Pile Strengthening Aeolian Sand Subgrade

Abstract

Abstract When the line project passes through a large area of aeolian sand, cement mixing piles are often used to reinforce the subgrade, which can effectively improve the bearing capacity of the subgrade, but its anti-liquefaction effect is worthy of in-depth evaluation. Intermittent earthquakes cause more than one liquefaction of aeolian sand subgrade, so it is worth further research on the re-liquefaction characteristics of cement mixing piles in treatment of aeolian sand subgrade. In this paper, a real-time comparative test (pile reinforced area and unreinforced area) is carried out through a shaking table, and the liquefaction and re-liquefaction characteristics of the reinforced subgrade are mainly explored. The experimental model will produce the following results under 0.4g EL Centro wave excitation:(1) The pore pressure will have multiple peaks, causing the surface of the model to float or sink. The phenomenon will be weakened by experiencing multiple earthquakes of the same level or using pile reinforcement;(2) The deeper the burial depth, the longer the time for the pore pressure to reach the maximum peak value. After multiple vibrations, the corresponding time of the shallow layer in the unreinforced area and the deep layer in the reinforced area doubles;(3) The cement mixing pile can improve the liquefaction and re-liquefaction resistance of aeolian sand foundation, and the effect is best in the shallow foundation, with an increase of more than 30%, and the deeper the burial depth, the lower the effect;(4) After the subgrade has experienced a strong earthquake, its resistance to liquefaction will be improved, but the acceleration response during the next earthquake will increase significantly.