主应力轴旋转下小偏压固结密实粉土崩塌特性及孔压模型研究.docVIP

 主应力轴旋转下小偏压固结密实粉土崩塌 特性及孔压模型研究# 沈扬1,2，张朋举1,2，闫俊1,2，刘汉龙1,2，张弛1,2* 5 10 15 20 25 30 35 40 45 （1. 河海大学岩土力学与堤坝工程教育部重点实验室，南京 210098； 2. 河海大学岩土工程研究所，南京 210098） 摘要：为研究主应力轴旋转复杂动应力对偏压固结粉土的性状演变影响，以空心圆柱试样为 对象，开展具有不同初始固结比的密实粉土(Dr＝70％)在不排水主应力轴循环旋转下的系列 试验。结果表明：(1)初始固结比不大于 1.5 时，主应力轴旋转导致试样发生中低应变崩塌 进而液化的脆性破坏模式；而大于此固结比，试样变为应变持续稳定开展至高应变，孔压最 终进入动态平衡的延性破坏模式。且不同固结比下试样发生崩塌液化和稳态延性破坏的孔压 峰值间不存在交叉。(2)小偏压固结试样的液化峰值孔压和崩塌孔压均随固结比增加而有规 律下降，但受动剪应力水平影响很小，这与等压固结试样的崩塌孔压值受制于剪应力水平有 很大差异。(3)相同初始球应力水平下，崩塌振次反映的小偏压固结试样强度高于等压固结 试样，但在偏压条件下，强度与固结比不存在单调变化关系。表明小偏压固结试样崩塌除受 制初始围压水平外，很大程度还取决于偏压程度。(4)基于上述试验结果，提出了主应力轴 循环旋转下小偏压固结粉土的孔压预测模型，该模型不仅突显了崩塌状态对相变及液化破坏 的重要预测作用，还反映了固结比和动剪应力对孔压开展的综合影响。 关键词：主应力轴旋转；固结比；粉土；崩塌；孔压 中图分类号：TU435 Collapse characteristics and unified pore water pressure model of anisotropically consolidated silt with high relative density under principal stress rotation SHEN Yang1,2, ZHANG Pengju1,2, YAN Jun1,2, LIU Hanlong1,2, ZHANG Chi1,2 (1. Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering, Hohai University, NanJing 210098; 2. Institute of Geotechnical Engineering, Hohai University, NanJing 210098) Abstract: In order to study the properties of anisotropically consolidated silt subjected undrained cyclic principal stress rotation(CPSR),series of tests were performed. The tested hollow cylinder silt samples had the initial relative density of 70% and were consolidated with different consolidation ratio(Kc) before CPSR.The results showed that for the samples with Kc ≤1.5,they collapsed at low or medium strain and liquefied, but when Kc 1.5, the samples’ strain increases stably and the pore water pressure developed into dynamic equilibrium states. And the peak values of pore pressure in dynamic equilibrium states were lower than those in the liquefaction failure states. On the other hand, differing from the isotropically consolidated samples,the samples with Kc between 1.1 and 1.5 had the maximum pore water pressure at liquefaction lower than the initial effecive sph