麦秸秆加筋石灰土的应力应变和Duncan-Chang模型参数研究

Deviator stress-strain characters of reinforced lime-soil with wheat straw and parameters of Duncan-Chang model

为增强石灰固化滨海盐渍土的抗变形能力,提出了麦秸秆加筋辅助处理的设想.考虑Duncan-Chang双曲线模型能较好地反映土的非线性特征,将Duncan-Chang模型和三轴压缩试验结果相结合,以加筋长度、质量加筋率、养护时间和围压为影响因素,探讨了不同条件下麦秸秆加筋石灰土的应力应变特性和相关模型参数.试验结果表明:1)养护初期,麦秸秆加筋石灰土和石灰土的应力应变曲线均表现为应变硬化型.养护21 d时,石灰土在4个围压下呈应变软化型,而麦秸秆加筋石灰土仅在100kPa围压下表现为应变软化型,在其他围压下依旧为应变硬化型.2)麦秸秆加筋石灰土的峰值主应力差和破坏应变均大于石灰土的,采用麦秸秆加筋可有效地提高石灰土的强度和抗变形能力.3)麦秸秆加筋石灰土在4个围压下的应力应变曲线的间距小于石灰土的,加筋技术更适用于在较低围压下改善土的强度和抗变形能力.4)麦秸秆加筋石灰土的强度增幅与加筋条件有关,对于直径61.8mm试样,圆柱形麦秸秆的适宜加筋长度和质量加筋率分别为20mm和0.25%.5)Duncan-Chang模型可较好的反映石灰土和麦秸秆加筋石灰土的应力应变的非线性特征.研究结果对实际工程中合理选择麦秸秆的加筋条件具有指导作用.

Reinforced soil with wheat straw was put forward for improving anti-deformation of solidified lime-saline soil.Triaxial compacted test of reinforced lime-soil with wheat straw is carried out to study the characters of deviator stress-strain and the parameters of Duncan-Chang hyperbola model as it can well reflect the nonlinear characteristics of soil.The related factors,such as reinforced length,reinforced ratio,curing-day and confining pressure,are chosen.Results indicate that： 1） Reinforced lime-soil and lime-soil both show strain hardening in early curing-day.After the curing-day of 21,lime-soil displays strain softening,but the former still performs strain hardening except for the confining pressure of 100 kPa.2）The maximum deviator stress and the failure strain of reinforced lime-soil are much larger than that of un-reinforced,reinforcement can improve the strength and anti-deformation of lime-soil effectively.3） The stress-strain curve distance of reinforced lime-soil in four confining pressure is less than that of lime-soil,the way of reinforcement can play a better role to the soil in lower confining pressure.4） The strength growth of reinforced soil depends on reinforced condition,and the suitable length and ratio is 20 mm and 0.25% respectively for the sample in diameter of 61.8 mm.5） By means of Duncan-Chang model,the stress-strain characteristic of lime-soil and reinforced lime-soil can be well indicated.This research can provides some guidance to select reinforced condition in engineering practice and to design and calculate the earth bank of reinforced saline soil.