碱性速凝剂对盾构壁后注浆浆体性能影响及微观机理研究  

Influence of Alkaline Accelerators on Performance of Backfill Grouting in Shield Engineering and Its Micro-mechanism

作　　者：朱文超 张雷 张亚洲 李明清 张建峰[3] 闵凡路[1] ZHU Wenchao;ZHANG Lei;ZHANG Yazhou;LI Mingqing;ZHANG Jianfeng;MIN Fanlu(College of Civil and Transportation Engineering,Hohai University,Nanjing 210024,China;CCCC Tunnel Engineering Co.,Ltd.,Beijing 100102,China;College of Mechanics and Materials,Hohai University,Nanjing 211100,China)

机构地区：[1]河海大学土木与交通学院,南京210024 [2]中交隧道工程局有限公司,北京100102 [3]河海大学力学与材料学院,南京211100

出　　处：《材料导报》2024年第19期40-46,共7页Materials Reports

基　　金：国家自然科学基金(52378394,52078189);中央高校基本科研业务费专项资金(B230201037)。

摘　　要：在盾构隧道壁后注浆工程中,选择合适的速凝剂,缩短壁后注浆浆体(浆体)的凝结时间,对控制地层沉降和管片上浮至关重要。采用Na_(2)CO_(3)和Li_(2)CO_(3)两种碱性速凝剂配制壁后注浆,分析了两者对浆体凝结时间、流动度经时损失和强度的影响规律及微观机制。结果表明:两类速凝剂均能明显缩短浆体的凝结时间,提高浆体强度,但同时导致浆体流动度经时损失加快。添加3%Na_(2)CO_(3)、0.5%Li_(2)CO_(3)分别使浆体凝结时间缩短至6.5 h和8 h,2.5 h后浆体流动度保持在220 mm,浆体14 d强度为3.8 MPa,相比未添加速凝剂浆体的强度提高30%以上。微观结构分析表明,碱性速凝剂通过与石膏和CH晶体反应,促进水泥矿物C_(3)A和C_(3)S水化,缩短了浆体的凝结时间;此外,碱性速凝剂促使水泥水化产生水滑石、方解石,并激发粉煤灰生成C-A-S-H,均使浆体结构更为致密,进而提高其后期强度。Appropriate accelerators were selected to reduce the setting time of grouting slurry,thereby controlling ground settlement and minimizing early segment flotation in backfill grouting of shield projects.Two typical alkaline accelerators,Na_(2)CO_(3)and Li_(2)CO_(3),were utilized in the preparation of backfill grouting,and their effects on setting time,fluidity loss,and slurry strength were analyzed.Experimental results demonstrated that both types of accelerators significantly reduced the setting time of the slurry and increased its strength.However,the loss of slurry fluidity over time also accelerated.By adding 3%Na_(2)CO_(3)and 0.5%Li_(2)CO_(3),the setting time was reduced to 6.5 hours and 8 hours,respectively,while the fluidity maintained at 220 mm after 2.5 hours.After 14 days,the slurry strength reached 3.8 MPa,which was more than 30%higher than that of the slurry without accelerators.Microstructure analysis revealed that the alkaline accelerators promoted the hydration of cement minerals C_(3)A and C_(3)S by reacting with gypsum and CH crystals,thus shortening the setting time of the slurry.Additionally,alkaline accelerators promoted the hydration of cement to produce hydrotalcite and calcite,and stimulated the formation of C-A-S-H from fly ash,all of which enhanced the density of slurry structure and thus improved later strength.

关 键 词：壁后注浆 碱性速凝剂 凝结时间 流动度经时损失 反应机理 

分 类 号：TU528.31[建筑科学—建筑技术科学]