双向地震荷载下水泥土变形和强度特性研究

Deformation and strength of cement-soil under bidirectional seismic loading

【目的】分析水平双向动剪应力、相位差对水泥土变形和动强度特性的影响规律,为水泥土桩复合地基在地震荷载作用下的破坏机理研究提供理论参考。【方法】在双向动剪应力为15.8,16.8,17.8,18.8,20.4kPa以及相位差为0°,45°,90°条件下,对水泥土进行水平双向动单剪试验,测定不同试验条件下水泥土的变形和动强度。【结果】动剪应变发展过程中存在明显的转折应变,且转折应变与破坏剪切次数的对数具有良好的线性关系;以转折应变作为水泥土的破坏标准,水泥土动强度与破坏剪切次数呈良好的反比例函数关系。3种相位差下导致水泥土破坏的临界动强度为15.2kPa。相位差为0°时,水泥土动强度最高;相位差为90°时,水泥土动强度最低。【结论】水平双向动剪应力和相位差对水泥土的动强度及动变形有较大影响。

[Objective] This study analyzed the effect of horizontal bidirectional dynamic shear stress and phase on deformation and dynamic strength of cement-soil to provide basis for the study of failure mechanism of cement-mixing pile composite foundation under seismic loading. [Method] The horizontal bi- directional dynamic simple shear tests of cement-soil were carried out with bidirectional dynamic shear stresses of 15.8,16.8,17.8,18.8,and 20.4 kPa and phases of 0%,45%,and 90%. The deformation and dynam- ic strength under different conditions were measured. [Result] The turning strain occurred in the develop- ment of dynamic shear strain, and the relationship between turning strain and logarithmic failure shear number was linear. Using the failure criteria of turning strain, dynamic strength and failure shear number had inverse proportion function relationship. The critical dynamic strength that can result in cement-soil failure under the three phases was 15.2 kPa. The dynamic strength of cement-soil was the highest when the phase was 0% and it was the lowest when the phase was 90%. [Conclusion] The horizontal bidirectional dy- namic shear stress and phase had significant impacts on dynamic strength and dynamic deformation of ce- ment-soil.