动态荷载不同幅值作用下软土流变特性测试分析

Testing and Analysis on Rheologic Characteristics of Soft Soil under Dynamic Loading with Different Breadth

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。

The practical investigating and theoretic analysis indicate that the rheologic action of the soft rock-soil may be accelerated by the dynamic loading,which induces more geotechnical engineering accidents and geologic disasters. The samples of marine deposit soft soil in Xiamen City are collected,and the rheologic characteristics curves such as dynamic stress-strain,the rheologic strain-time,etc under different breadth of dynamic loading of sinusoidal variation are tested using dynamic-triaxial device. The rheologic characteristics,rheologic rate and rheologic acceleration at four different breadths are analyzed. The research results indicate that all samples have the same varietal process as from decelerate rheology,relatively stable rheology to accelerate rheology stage. The dynamic strain slowly grows and the rheologic process is relatively stable when the breadth of dynamic loading is in low stress ranges of 10 ～20KPa. When the breadth of dynamic loading exceeds 40 kPa,the dynamic strain rapidly grows and the rheologic is in accelerating process till the samples destroy. The research results have theoretical and actual signification for us to open out the dynamic rheologic mechanical characteristic,explore the accelerating rheologic laws and the rheologic destabilizing dynamic condition of soft rock-soil under dynamic loading.