动荷载作用下粉煤灰改性黄土的震陷特性

Seismic Subsidence Behavior of Fly-ash-modified Loess under Dynamic Loading

针对黄土地区实现工程施工材料本土化和科学利用粉煤灰问题,对不同配比条件下粉煤灰改性黄土进行重塑非饱和试件的动三轴震陷试验,研究其在动荷载作用下的震陷特性,分析粉煤灰掺入量对动变形模量和动残余应变的影响变化规律。研究结果表明:粉煤灰掺入量对黄土震陷性质的影响较大。相同固结应力水平下,动变形模量和动残余应变随粉煤灰掺入量呈现出不同的变化规律,随着粉煤灰掺入量的增加,黄土动变形模量也随之增大,残余应变则减小。动变形模量与动残余应变之间的变化趋势满足幂函数关系;黄土掺加约20%粉煤灰改性后就能够有良好的抗震陷性能。研究成果可为黄土地区地基的抗震防震设计提供借鉴依据,具有重要的工程实用价值。

In order to obtain raw material locally and make optimal use of fly ash in engineering construction in loess areas,we conducted a series of dynamic triaxial tests on unsaturated remolded loess specimens that had been modified with different proportions of fly ash.Based on the test results,we studied the seismic subsidence properties of loess based on the improvement afforded by the fly ash,and derived change laws for the dynamic modulus of deformation and the dynamic residual strain for different proportions of fly ash.The results show that the quantity of dope in fly ash significantly influences the seismic subsidence properties of loess.The changes in the dynamic modulus of deformation and in the dynamic residual strain vary with respect to the improvement afforded by fly ash under the same consolidation stress,i.e.,the former becomes larger while the latter become smaller and the relationship between them is well described by the power function.Moreover,we verified that the anti-seismic subsidence behavior of the loess specimens was much better when the proportion of fly ash is about 20%.Thee research findings provide a scientific basis for establishing anti-seismic designations for foundations in loess areas,and thus have important application value.