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理论分析和实际研究表明,动态荷载作用会加速软弱岩土的流变,导致更多的岩土工程事故和地质灾害。采集厦门海相沉积软土,采用人工制样方法,在动态三轴仪上测试了正弦荷载不同幅值作用下试样的动应力—应变、流变应变—时间关系等流变特性曲线,分析了不同动载幅值条件下试样各个加载阶段动态流变特性、流变速率与流变加速度等变化过程。研究结果表明:试样在动态荷载不同幅值作用过程中都表现出从减速流变、相对稳定流变到加速流变等阶段。当动载作用幅值在10~20 kPa低应力范围内时,动应变增长缓慢,表现出相对稳定的流变过程,而动载作用幅值超过40 kPa时,动应变增长迅速,进入加速流变阶段,直到试样破坏。研究结果对揭示动载作用下软弱岩土动态流变力学特性,对探索软弱岩土加速流变规律、岩土流变失稳的动力学条件等具有一定的理论和现实意义。
Theoretical analysis and practical studies show that the dynamic load can accelerate the flow of soft soil and lead to more geotechnical accidents and geological disasters. The marine soft clay was collected from Xiamen. The dynamic triaxial test was used to test the dynamic stress-strain and rheological strain-time curves of the samples under different sinusoidal loads. The dynamic rheological properties, the rheological rate and the rheological acceleration of the specimen during different loading stages under different dynamic load were analyzed. The results show that the specimens show different stages from the decelerating rheological, the relatively steady rheological to the accelerating rheological during the dynamic load with different amplitude. When the amplitude of dynamic loading is in the low stress range of 10 ~ 20 kPa, the dynamic strain increases slowly and shows a relatively stable rheological process. When the dynamic load amplitude exceeds 40 kPa, the dynamic strain increases rapidly and enters the accelerating flow Change phase until sample breaks. The research results have certain theoretical and practical significance for revealing the dynamic rheological properties of soft soil under dynamic loading, exploring the accelerating rheological law of soft soil and the dynamic conditions of geotechnical instability.