地聚物稳定粗粒填料静动力学特性试验研究

Static and dynamic mechanical properties of coarse-grained fillings stabilized with geopolymer binder

地聚物具有高强、致密、低导热、资源节约等特点,其在抗震安全性、资源获取可行性等方面均符合高铁路基工程粗粒填料改良的需求。通过不同偏高岭土与碱激发材料配比下的地聚物稳定细粒填料单轴抗压强度试验和不同块石含量、围压下的地聚物稳定粗粒填料动三轴试验,研究了地聚物材料的配比关系及其在细粒填料稳定中的最优掺量,探讨了块石含量和围压对地聚物稳定粗粒填料动力特性的影响规律。结果表明:偏高岭土基地聚物中原材料与碱激发剂的最佳配比为2:1,且二者在细粒填料稳定中的最佳掺量为15%;地聚物稳定粗粒填料最大动剪切模量与块石含量存在线性增长关系,但与围压呈近似非线性增长;归一化剪应变下,地聚物稳定粗粒填料动剪切模量比G/G_(max)均分布在窄带内,阻尼比则离散性较大。研究成果可为地聚物稳定粗粒填料的应用推广提供设计参数依据。

Geopolymer is characterized by high strength,denseness,low thermal conductivity,and resource conservation,and it meets the needs of coarse-grained fill improvement for high-speed railway roadbed engineering in terms of seismic safety and feasibility of resource acquisition.The unconfined compression strength tests of geopolymer-stabilized fine-grained fillings with different mixing ratios of metakaolin and alkali-activator and the dynamic triaxial tests of geopolymer-stabilized coarse-grained fillings with different rock block contents and confining pressures were carried out.The mixing ratio of raw material and alkali activator for composing metakaolin-based geopolymer and their optimum mixing ratio in fine-grained fillings were analyzed.The impacts of rock block content and confining pressure on the dynamic characteristics of the geopolymer-stabilized coarse-grained fillings were discussed.The results indicated that the optimum ratio of metakaolin and alkali activator for composing geopolymer was 2:1,and their optimum content in fine-grained fillings was 15%;the maximum dynamic shear modulus of geopolymer-stabilized coarse-grained fillings had an approximately linear relationship with the rock block content and a non-linear relationship with the confining pressure;when the shear strain was normalized,the dynamic shear modulus ratios of the geopolymer-stabilized coarse-grained fillings were distributed in a narrow band,while the damping ratio showed a relatively high dispersion in values.The results of this study can provide the design parameter basis for the application and popularization of geopolymer-stabilized coarse-grained fillings.