干湿循环作用下氯氧镁水泥基多相胶凝材料改性固化淤泥的水力-力学特性

Hydro-mechanical properties of sludge stabilized with magnesium oxychloride cement-based multi-cementitious materials under influences of drying-wetting cycles

为探明以绿色氯氧镁水泥为基、以工业副产品粉煤灰和矿渣为辅的多相胶凝材料对已初步固化的淤泥进一步改性而得的“改性固化淤泥”用作路基填料的长期性能,以武汉东湖段的改性固化淤泥为研究对象,通过系列试验得到其经历不同次数干湿循环作用(N_(DW))的土-水特征曲线(SWCC)以及非饱和状态下的回弹模量(M_(R))、无侧限抗压强度(q_(u))、刚度参数(E_(1%)和S_(u1%))和累积塑性应变(ε_(p))。结果表明:(1)干湿循环使改性固化淤泥试样产生大量的宏观裂缝和微观裂隙,显著地降低了其在低吸力段的持水能力,但对高吸力段的持水能力基本无影响;(2)q_(u),E_(1%),S_(u1%)和M_(Rrep)均随着N_(DW)的增加而衰减,其衰减机理具有相似性,依此建立了衰减因子(χ_(DW))-N_(DW)关系模型:(3)经历干湿循环后,M_(R)对围压(σ_(c))变化的敏感性有所增加,而对偏压(σ_(d))则有两种不同的反应;(4)未经历干湿循环改性固化淤泥试样的ε_(p)表现为塑性稳定型,而经历干湿循环后,在高σ_(d)和低σ_(c)水平下,试样ε_(p)转变为塑性过渡型。

In order to investigate the long-term performance of"modified cured silt",which is a multi-phase cementitious material based on green magnesium chloride cement and supplemented by fly ash and slag as the industrial by-products,by further modifiying the initially cured silt as the roadbed filler,the soil-water characteristic curve(SWCC),rebound modulus(M_R),unconfined compressive strength(q_u),stiffness parameters(E_(1%)and S_(u1%))and cumulative plastic strain(ε_p)of the modified cured silt in East Lake section of Wuhan are obtained through a series of tests after various drying-wetting cycles.The results show that:(1)The drying-wetting cycles produce a large number of macroscopic cracks and microscopic fissures in the modified cured silt specimens,which significantly reduce their water holding capacity in the low suction section,but have essentially no effects on the water holding capacity in the high suction section.(2)q_u,E_(1%),S_(u1%)and M_(Rrep)all decay with the increasing N_(DW),and their decay mechanisms are similar,and the decay factor(χ_(DW))-N_(DW)relationship model is established accordingly.(3)After undergoing the drying-wetting cycles,the sensitivity of M_(R)to changes in the periapical pressure(σ_c)increases,whereas two different responses to the bias pressure(σ_d)are observed.(4)ε_(p)of the modified cured silt specimens that do not undergo the drying-wetting cycles exhibits a plastic stable type,while after undergoing the drying-wetting cycles,sp of the specimens transforms into a plastic transitional type at highσ_(d)and lowσ_(c)levels。