循环荷载作用下黄原胶改良粉土动力特性试验研究  

Experimental study on dynamic characteristics of xanthan gum modified silt under cyclic loading

作　　者：庄心善 李肖飞 杨端 张博文 ZHUANG Xinshan;LI Xiaofei;YANG Duan;ZHANG Bowen(School of Civil Construction and Environment,Hubei University of Technology,Wuhan 430068,China)

机构地区：[1]湖北工业大学土木建筑与环境学院,湖北武汉430068

出　　处：《铁道科学与工程学报》2024年第11期4532-4542,共11页Journal of Railway Science and Engineering

基　　金：国家自然科学基金资助项目(51708190)。

摘　　要：为研究循环荷载作用下的黄原胶改良粉土动力特性及作用机理,对加入不同掺量黄原胶的试样进行无侧限抗压强度试验,得出其最佳掺量。基于此利用GDS动三轴仪对改良土进行动三轴试验,研究不同围压、频率对黄原胶改良粉土的骨干曲线、动剪切模量、剪切模量比及阻尼比的影响规律,并对试验结果进行拟合,利用扫描电镜试验进一步分析黄原胶改良粉土的微观形态,揭示其力学性能优化机理。试验结果表明,改良土的无侧限抗压强度随着黄原胶掺量和养护时间的提高而提高,当黄原胶掺量为1.5%时,抗压强度达到峰值900 kPa,达到素土强度的3.4倍,改良效果最佳。在同一剪应变水平下,随着围压的增大,骨干曲线、G_(d)-γ_(d)衰减曲线均向上移动,而λ-γ_(d)增长曲线逐渐降低,不同频率对其影响规律与围压作用结果基本一致。考虑围压和频率的影响,采用Stokoe方程模型与剪应变的经验关系,得到了黄原胶改良粉土的动剪切模量比归一化拟合模型,拟合结果显示,建立的模型能较好地描述黄原胶改良土的剪切模量比随剪应变的变化规律。结合微观分析发现,加入黄原胶后形成胶体网络结构,填充颗粒间的空隙与土颗粒相互胶结成致密结构,宏观上表现为改良土体强度的提升。研究结果有助于揭示黄原胶改良粉土动力特性规律,进而为粉土路基相关工程案例提供一定理论参考。To study the dynamic properties and mechanism of xanthan gum improved silt under cyclic loading,the specimens with different dosage of xanthan gum were subjected to unconfined compressive strength tests to obtain the optimal dosage.The dynamic triaxial tests were carried out on the improved soil by using the GDS dynamic triaxial instrument.The influence laws of different peripheral pressures and frequencies on the backbone curves,dynamic shear modulus,shear modulus ratio,and damping ratio of the xanthan gum improved silt were studied.The results were fitted to the test results to further analyze its micro-morphology and reveal the optimization mechanism of its mechanical properties.The test results were also fitted,and the microscopic morphology of xanthan gum improved silt was further analyzed using scanning electron microscope tests to reveal the optimization mechanism of its mechanical properties.The test results are drawn as follows.The unconfined compressive strength of the improved soil increases with the increase of xanthan gum dosage and maintenance time.When the xanthan gum dosage is 1.5%,the compressive strength reaches the peak value of 900 kPa,which is 3.4 times of the strength of the plain soil,and the improvement effect is the best.At the same shear strain level,with the increase of the perimeter pressure,the backbone curve and the G_(d)−γ_(d)decay curve move upward.While theλ−γ_(d)growth curve decreases,the different frequency has the same effect on the law.Considering the effect of perimeter pressure and frequency,the empirical relationship between Stokoe’s equation model and shear strain is used to obtain the normalized fitting model of dynamic shear modulus ratio of xanthan gum-amended silt,and the fitting results showed that the established model can better describe the changing law of shear modulus ratio of xanthan gum-amended soil with the shear strain.Combined with the microanalysis,it was found that the addition of xanthan gum formed a colloidal The microanalysis shows that the add

关 键 词：黄原胶 循环荷载 动三轴试验 动剪切模量 阻尼比 

分 类 号：TU443[建筑科学—岩土工程]