循环荷载下滨海风积砂孔压发展规律试验研究

Experimental Study on the Law of Development of Pore Water Pressure for Coastal Aeolian Sand Subjected to Cyclic Loading

利用GDS动三轴试验系统,在不同的基准应变下对福建漳浦滨海风积砂施加不同幅值的等幅循环应变荷载,分析了滨海风积砂在循环应变作用下的孔压发展规律。试验结果表明:滨海风积砂的孔压在初始段迅速增长,之后循环应变幅值不同,孔压有不同的动力响应。小幅值作用下,过渡段大致为"S"发展趋势,后期试样结构崩溃,孔压值迅速达到围压值。密实砂抗液化能力随着基准应变的增大和循环应变幅值的减小而增大,但是中密砂受基准应变的影响很小。根据实验数据建立孔压增长对数模型,模拟结果与试验结果一致性较好。

Undrained dynamic triaxial tests were carried out using GDS dynamic triaxial testing system on coastal aeolian sand. Different amplitudes and datum were adopted for the strain control tests. The dynamic characteristics of the coastal aeolian sand were analyzed. The experimental results showed that pore water pressure grew rapidly in the beginning under dynamic loading,and then had different dynamic responses to various cyclic strain amplitudes. Under small strain amplitude,the pore pressure curve developed as an ＂S＂shape,and then increased rapidly to confining pressure due to sample failure. The liquefaction resistance of dense sand increased with the increase of datum strain and the decrease of the amplitude of cyclic strain. However,for medium dense sand,the liquefaction resistance was less influenced by the datum strain. A logarithmic model of pore water pressure was developed based on the experimental data. The simulation results show a good consistency with the laboratory tests.