纳米二氧化硅固化黄土的循环简单剪切行为及热学性能的试验研究

Experimental study on cyclic simple shear behavior and thermal property of loess treated with nanosilica

摘要

纳米材料逐渐出现在岩土工程领域，用以处理问题地基和防治滑坡。旨在调查纳米二氧化硅处理黄土的循环抵抗强度和循环后抗剪强度的发展。通过一系列循环简单剪切和循环后单调剪切试验，探讨了纳米二氧化硅掺量和初始有效固结应力对处理黄土强度的影响。并通过扫描电子显微镜(SEM)和X射线衍射(XRD)测试分析了复合体的微观结构和结晶相。此外，还对不同含水率和纳米二氧化硅掺量下黄土的导热系数(温度场的重要参数)进行了试验。根据试验结果得出，随着纳米二氧化硅掺量的增加，黄土的循环抵抗能力和循环后剪切强度不断增加。纳米二氧化硅主要通过填充、裹附、强化胶结这三种机制来固化黄土，不与土体成分发生化学反应。另一方面，纳米二氧化硅是一种优良的隔热材料，可以有效降低黄土的导热系数。

Abstract

Nanomaterials are gradually appearing in the field of geotechnical engineering to treat problematic foundations and prevent landslides. The cyclic resistance strength and post-cyclic shear strength development of solidifying loess with nanosilica were investigated. The effects of nanosilica dosage and initial effective consolidation stress on the strength of treated loess were investigated through a series of cyclic direct simple shear and post-cyclic monotonic shear tests. Microstructures and crystalline phases of loess treated with nanosilica were analyzed by scanning electron microscopy(SEM) and X-ray diffraction(XRD) tests. In addition, the thermal conductivity of loess was tested at different water content and nanosilica doping. Based on the test result, it was concluded that the cyclic resistance and post-cyclic shear strength of loess increased continuously with the increase of nanosilica doping. Nanosilica solidifies loess through three mechanisms: filling, encapsulation, and reinforcing cementation, without chemical reaction with the soil components. On the other hand, nanosilica is an excellent thermal insulation material that can effectively reduce the thermal conductivity of loess.

关键词

纳米二氧化硅 / 黄土 / 循环简单剪切试验 / 导热系数

Key words

nanosilica / loess / cyclic direct simple shear tests / thermal properties

Author summay

孙 渊(1999—), 男, 硕士研究生, 主要从事岩土工程防灾减灾研究。E-mail: [e-mail]

基金资助

青海省科技厅科技成果转化专项项目(2022-SF-159)