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基于完全不排水试验的已有研究结果表明,只有在饱和松砂中才可能发生流滑现象,较密实的饱和剪胀性砂土在初始液化后的不排水循环或单调剪切作用条件下,则会呈现出所谓往返活动性或抗剪强度恢复现象。然而,实际土工抗震边值问题中的饱和砂土在许多情况下并不能够被视为处于完全不排水条件,可能由于土性和变形等因素的不同而处于剪切排水甚至剪切吸水条件。通过对饱和砂土液化后常剪切吸水率试验结果的分析指出,剪切吸水条件可能导致剪胀性砂土的抗剪能力显著降低、甚至发生流滑现象。基于可逆性与不可逆性剪切体应变的概念以及3种体应变分量变化的特性规律,推导出剪切吸水条件下的体变约束条件。不同排水条件下的体变约束条件决定了剪胀性砂土应力-应变响应的不同变化,当满足自由吸水剪切条件时饱和砂土会出现具有流动特征的大变形;当满足强制吸水剪切条件时会发生具有非稳定特征的流滑现象。
The results of previous studies based on completely undrained tests show that the slippery phenomenon is likely to occur only in saturated sands. Compacted saturated dilatable sand, under undrained cyclic or monotonic shear after initial liquefaction, It will show the so-called return activity or shear strength of the phenomenon. However, the saturated sand in the actual geo-seismic boundary value problem can not be regarded as being completely undrained in many cases and may be in the condition of shearing drainage or even shearing water absorption due to different factors such as soil and deformation. Based on the analysis of the results of the test of water absorption of saturated sand after liquefaction, it is pointed out that the shearing water absorption conditions may cause the shear capacity of dilatant sand to decrease significantly and even slippery phenomenon. Based on the concept of reversible and irreversible shear strain and the characteristic law of the variation of three kinds of body strain components, the body constraint conditions under shear water absorption are deduced. Under different drainage conditions, the body-building constraints determine the different changes of the stress-strain response of the dilatable sand. When the conditions of free water absorption are satisfied, the large deformation with the flow characteristics will occur in the saturated sand. Flow-slip phenomena with unsteady characteristics can occur under conditions.