饱和黏性土和砂砾石料振动孔压的试验研究

Experimental study on dynamic pore water pressure of saturated cohesive soil and gravel

在国内外主要孔压发展模型的基础上，对某土石坝心墙防渗黏性土和坝基砂砾石料饱和试样进行动三轴试验，提出了两种材料的顾淦臣孔压模型，并对砂砾石料的孔压发展规律作了深入地分析，提出了不同固结比坼时振动孔压比和振次比的函数关系。试验结果表明，动孔压随振动周数和振动强度的增加而增加，随固结应力比或初始剪应力比的增加而减小；无论等压或偏压固结，黏性土均不会出现动孔压ud等于围压力σ3c的液化现象，其孔压比Ru均小于0．5，多数试样Ru=0．1-0．4；当等压固结Kc=1．0时，砂砾石料最终孔压值均可达到围压；偏压固结K≥1．5后，试样是否达到Ru=Ud／σ3c=1．0取决于动应力σd是否大于主应力差（σ1c-σ3c），即σd是否形成拉应力，使试件伸长，但当Kc很大后，σ1c和σ3c相差太大，需施加非常大的瓯才能使其应力应变反向，试样的大变形先于Ru=1．0的应力状态出现，即不可能达到初始液化；固结比疋对不同土料动孔压的影响是不同的。

The research outcomes at home and abroad about dynamic pore water pressure developing models are firstly reviewed; then the dynamic triaxial tests which used saturated core cohesive soil and dam foundation gravel of a rockfill dam were performed; and Gu Gan-chen models of these two materials were put forward. And dynamic pore water pressure developing rules of gravel were analyzed in detail. The results of dynamic intensity tests show that with the increasing of vibration times and vibration intensity, dynamic pore water pressure increases. While with the increasing of consolidated stress ratio, dynamic pore water pressure decreases. For cohesive soil, in spite of equivalent-pressure or unequivalent-pressure consolidation, liquefaction phenomenon didn＇t appear. For gravel, final dynamic pore water pressure could all reach confining pressure under equivalent-pressure consolidation, and when consolidated stress ratio Kc exceeds or equals to 1.5, whether samples could liquefy lied on that dynamic stress ad could make samples stretch or not. And the effects of consolidated stress ratio Kc on various soils were different.