石灰-偏高岭土改良遗址土强度劣化特性的冻融循环效应  

Strength deterioration characteristics of lime-metakaolin improved earthen site soil under freeze-thaw cycles

作　　者：李新明[1,2] 张浩扬 武迪 郭砚睿 任克彬 谈云志[4] LI Xin-ming;ZHANG Hao-yang;WU Di;GUO Yan-rui;REN Ke-bin;TAN Yun-zhi(School of Civil Engineering and Architecture,Zhongyuan University of Technology,Zhengzhou,Henan 450007,China;Research Center of Environmental Geotechnical Engineering and Underground Engineering Disaster Control Engineering of Henan Province,Zhongyuan University of Technology,Zhengzhou,Henan 450007,China;Henan Provincial Architectural Heritage Protection and Research Institute,Zhengzhou,Henan 450007,China;Key Laboratory of Geological Hazards on Three Gorges Reservoir Area of Ministry of Education,China Three Gorges University,Yichang,Hubei 443002,China)

机构地区：[1]中原工学院建筑工程学院,河南郑州450007 [2]中原工学院河南省环境岩土工程与地下工程灾害控制工程研究中心,河南郑州450007 [3]河南省文物建筑保护研究院,河南郑州450007 [4]三峡大学三峡库区地质灾害教育部重点实验室,湖北宜昌443002

出　　处：《岩土力学》2023年第6期1593-1603,共11页Rock and Soil Mechanics

基　　金：河南省高等学校青年骨干教师资助计划项目(No.2019GGJS142);河南省高等学校重点科研项目计划基础研究专项(No.20ZX009);国家自然科学基金(No.51509274);河南省科技攻关项目(No.202102310584,No.222102320060)。

摘　　要：中原地区处于季冻区,周期性冻结与融化对遗址土体结构有显著影响。为探究石灰偏高岭土(L-MK)在抗冻融循环方面替代天然水硬性石灰(NHL)用于土遗址修复工作的可行性,以石灰、偏高岭土和遗址土为主要原料,对经历不同冻融循环次数的L-MK改良土试样分别进行质量损失测试、无侧限抗压强度试验和劈裂抗拉强度试验,系统研究其强度特性的冻融循环效应;并取部分试样进行X射线衍射(XRD)、热重(TG)、电镜扫描(SEM)等微观试验,揭示L-MK改良土强度劣化规律的内在机制。结果表明:试验配合比下,L-MK改良土的抗冻性能优于NHL改良土,偏高岭土掺量的增加有助于提高L-MK改良土强度;随着冻融循环次数的增加,L-MK改良土应力-应变曲线的应变软化特征呈减弱趋势,无侧限抗压强度和劈裂抗拉强度单调衰减,但经历30次冻融循环后L-MK改良土无侧限抗压强度和劈裂抗拉强度分别高于NHL改良土3.79倍和1.16倍以上。这与L-MK及NHL改良土生成的水化产物(CSH和C_(4)AH_(13)等)受冻融循环的影响规律基本一致。The Central Plains are located in an area that experiences seasonal freeze-thaw cycles,which can have significant effects on the soil structure of soil relics.To determine if lime-metakaolin(L-MK)is a feasible alternative to natural hydraulic lime(NHL)for earth site restoration work,tests were conducted using lime,metakaolin and silty sand from the site as main raw materials.Mass loss,unconfined compressive strength and splitting tensile strength tests were carried out on L-MK improved silty sand soil undergoing different numbers of freeze-thaw cycles to study its strength characteristics in depth.X-ray diffraction(XRD)thermogravimetry(TG),and scanning electron microscope(SEM)microscopic tests were also performed on some samples to reveal the internal mechanism of strength deterioration law of L-MK improved soil.Results indicate that L-MK improved soil has better freeze-thaw cycle resistance than NHL improved soil under the experimental mix ratio.Increasing the content of metakaolin improves the strength of L-MK improved soil.As the number of freeze-thaw cycles increases,the strain softening characteristics of L-MK improved soil show a weakening trend,and unconfined compressive strength and tensile strength decrease monotonically.After 30 freeze-thaw cycles,the unconfined compressive strength and splitting tensile strength of L-MK improved soil are about 3.79 and 1.16 times higher than that of NHL improved soil,respectively.The variation of strength is consistent with hydration products such as CSH and C_(4)AH_(13) generated by hydration reaction under the influence of freeze-thaw cycle for L-MK and NHL improved soil.

关 键 词：土遗址 冻融循环 石灰偏高岭土 水硬性石灰 微观结构 

分 类 号：TU449[建筑科学—岩土工程]