摘要
注浆技术作为常用的岩体加固手段已被广泛应用于地下工程中,但注浆加固效果常常受到地下工程所处地层高温、高地应力等环境因素的显著影响。因此,开展不同外界条件下(如温度、围压等)岩体浆液流动扩散机制的研究,对于提高深部软弱围岩的注浆加固效果及保障施工安全有着重要的工程实际意义。本文基于低场核磁共振技术对裂隙砂岩试样开展渗透注浆试验研究,对注浆过程中浆液的核磁信号特征进行实时跟踪测试,分析不同温度、不同围压、不同浆液流速和不同裂隙数量下岩石的浆液注入量、有效注浆时间和浆液充填速率的变化规律。试验结果表明:超细水泥浆液的潜伏期随温度升高而缩短,且浆液的黏度具有显著的时变性和温度相依性。裂隙岩石的浆液最终注入量随着温度和围压的升高而减小。有效注浆时间与浆液流速的增大成反比,与温度的升高成正比。浆液充填速率随着围压的升高而降低,且对围压变化的敏感程度逐渐降低。多裂隙试样中浆液注入量较单裂隙更高,有效注浆时间更短,浆液充填速率更大。在较高浆液流速和较高围压下,微孔隙中浆液充填速率占比明显增大,浆液优先向微孔隙中运移扩散,当微孔隙内浆液达到一定充填度后才向细孔隙和大孔隙中扩散;而温度和裂隙数量对浆液在孔隙中的扩散机制影响较小,各尺寸下浆液充填速率占比变化很小。研究结果为深部软弱岩体的注浆参数设计和选择提供必要指导。
As a common rock reinforcement method,grouting technology has been widely used in underground engineering,while the reinforcement performance is largely affected by the external environmental factors such as high temperature and high geo-stresses. Therefore,it is of great practical significance to study the flow and diffusion mechanism of slurry in fractured rock under different external conditions to enhance the grouting reinforcement effects of deep soft rocks and to ensure the construction safety. In this paper,infiltration grouting tests on fractured sandstone samples were carried out using the low-field NMR technology. During the grouting process,the NMR signal characteristics of the slurry were monitored in real time,and the parameters such as the slurry injection volume,the effective grouting time and the slurry-filling rate were analyzed under the conditions of different temperatures,different confining pressures,different slurry flow rates and different numbers of fractures. The results show that the incubation period of the superfine cement slurry decreases with increasing the temperature and that the slurry viscosity performs significant time-dependent and temperature-dependent characteristics. The final slurry injection volume of the fractured rock decreases with increasing the temperature and the confining pressure. The effective grouting time is inversely proportional to the slurry flow rate while positively proportional to the temperature. The slurry filling rate decreases as the confining pressure increases,accompanying with a decreased sensitivity to the confining pressure. Compared to the samples with single fracture,multi-fractured samples show higher slurry injection volume,shorter effective grouting time and larger slurry filling rate. Under a higher slurry flow rate and a higher confining pressure,the percentage of the slurry filling rate in the micro-pores increases significantly,and the slurry preferentially transports into the micro-pores. When the micro-pores reach a certain filling leve
作者
吴志军
张锶浪
翁磊
刘泉声
周原
WU Zhijun;ZHANG Silang;WENG Lei;LIU Quansheng;ZHOU Yuan(School of Civil Engineering,Wuhan University,Wuhan,Hubei 430072,China;The Key Laboratory of Safety forGeotechnical and Structural Engineering of Hubei Province,Wuhan University,Wuhan,Hubei 430072,China;State KeyLaboratory of Water Resources and Hydropower Engineering Science,Wuhan University,Wuhan,Hubei 430072,China)
出处
《岩石力学与工程学报》
EI
CAS
CSCD
北大核心
2022年第4期660-675,共16页
Chinese Journal of Rock Mechanics and Engineering
基金
国家自然科学基金资助项目(42077246,41772309,52004182)。
关键词
岩石力学
裂隙岩体
核磁共振
T2谱曲线
浆液扩散
rock mechanics
fractured rock
nuclear magnetic resonance(NMR)
T2 distribution curve
slurry diffusion
