应力控制模式下粉土动力崩塌特性的PFC数值试验研究  

PFC numerical experiments on dynamic collapse behaviors of silt under stress controlled mode

作　　者：沈扬[1] 陶明安[2,1] 徐国建 

机构地区：[1]河海大学岩土力学与堤坝工程教育部重点实验室,江苏南京210098 [2]铁道第三勘察设计院集团有限公司,天津300142 [3]上海市政建设集团,上海200092

出　　处：《岩土工程学报》2015年第12期2280-2285,共6页Chinese Journal of Geotechnical Engineering

基　　金：中央高校基本科研业务费专项资金项目(2015B17114)

摘　　要：针对波浪荷载引发近海粉土的崩塌特性,采用PFC颗粒流软件进行应力控制式主应力方向突变模拟加载试验。结果表明加载引发粉土崩塌,临界崩塌状态下试样内部应力发展到较高水平,颗粒结构内容有剪应力水平集中的连通区域形成,而应变幅值较小;土体在崩塌点后仍具一定强度,且与动剪应力水平有关。在此基础上,研究了围压与动剪应力比对粉土崩塌特性影响。发现各组试样滞回圈的形态均随着初始围压的增大而呈现逐步紧缩的趋势。同时也从能量法观点解释了相关滞回圈在不同围压下开展特性的内在原因。相关的研究结果,从细观机理层面揭示了崩塌对于粉土破坏的前兆作用,有助于实际工程中分析预测粉土在动力失稳前后的性状特征。To study the collapse behaviors of silt under wave load, the stress controlled dynamic simulation tests are carried out using PFC2 D. The results show that the loading induces the collapse of silt. When the state approaches the collapse, the internal stresses of silt reach high levels and the concentrated shear stress appeares in some connected regions. But the critical strain level is not high. At the collapse, the silt still remaines to have residual strength to some extent, which is related to the level of dynamic stress. Then the effects of confining pressure and cyclic shear stress ratio on the collapse behaviors of silt are studied. It is found that with the increase of the initial confining pressure, the hysteresis loops of each group of samples show gradual tightening trends. Besides, the intrinsic reason of the development of hysteresis loops is also elaborated in the view of energy method. The research results reveal that the collapse is key to the failure forecast of silt, and they are beneficial to the analysis of the behaviors of silt around dynamic instability.

关 键 词：崩塌 粉土 颗粒流模拟 应力控制 

分 类 号：TU43[建筑科学—岩土工程]