黄原胶改良粉土的动强度特性及其微观分析

Dynamic Strength Characteristics and Microscopic Analysis of Silt Improved by Xanthan Gum

地震和车辆振动等荷载易对路基粉土的强度造成破坏,通常使用水泥和石灰等传统材料对粉土进行改良,但对环境造成了不可逆的损害,研究环境友好型生物聚合物——黄原胶改良粉土动强度特性及机理显得非常必要.通过改变黄原胶的掺量,采用扫描电镜和动三轴仪对黄原胶改良粉土进行一系列的微观分析和动强度试验.试验结果表明:动强度曲线符合幂函数关系,且随着黄原胶掺量的增加而上移.动黏聚力随着黄原胶掺量的增加而增大,强化效果在掺量较大时趋于平稳;而动内摩擦角受黄原胶掺量的影响较小.由微观分析可知,随着黄原胶掺量的增加,黄原胶有效填充了土颗粒间的孔隙并附着在土颗粒表面,形成纤维状和网状结构,从而增强了土颗粒间的联结能力,并导致了改良土的动强度和动黏聚力的提高.上述研究成果可为相关岩土工程的设计和施工提供科学依据,同时满足了黄河流域生态保护和高质量发展战略的需求.

The strength of subgrade silt is easily damaged by loads such as earthquake and vehicle vibration.Traditional materials such as cement and lime are usually used to improve the silt,but it causes irreversible damage to the environment.Therefore,it is very necessary to study the dynamic strength characteristics and mechanism of silt improved by environmentally friendly biopolymer-xanthan gum.A series of microscopic analyses and dynamic strength tests were conducted on xanthan gum improved silt by varying the content of xanthan gum using scanning electron microscope and dynamic triaxial instrument.The test results show that the dynamic strength curve conforms to the power function relationship and shifts upward with the increase of xanthan gum content.The dynamic cohesion increases with the increase of xanthan gum content,and the strengthening effect tends to be smooth when the content is larger;while the dynamic internal friction angle is less affected by the content of xanthan gum.The microscopic analysis shows that with the increase of xanthan gum content,xanthan gum effectively fills the pores between soil particles and adheres to the surface of soil particles to form fibrous and reticular structures,which enhances the association ability between soil particles and leads to the increase of dynamic strength and dynamic cohesion of improved silt.The above research results can provide scientific basis for the design and construction of related geotechnical projects,and meet the needs of ecological protection and high-quality development strategy in the Yellow River basin.