富水粉细砂层盾构渣土改良与喷涌防治试验研究
郭世情1陈汉2蒋沛峰1郭鹏飞3孙毅3许平保4狄宏规4
Experimental Study on Slurry Improvement and Gushing Control in Water-rich Silty Fine Sand Layers
GUO Shiqing1CHEN Han2JIANG Peifeng1GUO Pengfei3SUN Yi3XU Pingbao4DI Honggui4
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作者信息:1.中国铁建股份有限公司南京地铁9号线一期工程施工总承包， 210019， 南京
2.南京地铁集团有限公司， 210008， 南京
3.中铁十五局集团有限公司， 200070， 上海
4.同济大学交通学院， 201804， 上海
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Affiliation:1.Nanjing Metro Line 9 Phase I Construction Contract, China Railway Construction Corporation Limited, 210019, Nanjing, China
2.Nanjing Metro Group Co., Ltd., 210008, Nanjing, China
3.China Railway 15th Bureau Group Co., Ltd., 200070, Shanghai, China
4.College of Transportation, Tongji University, 201804, Shanghai, China
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关键词:
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Key words:
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DOI:10.16037/j.1007-869x.20230555
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中图分类号/CLCN:TU411.2
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栏目/Col:土建工程
摘要:
［目的］土压平衡盾构施工穿越富水粉细砂层时，因地层摩擦性大、流塑性差、渗透性高等特点，需通过渣土改良提升施工安全性。［方法］以南京地铁9号线（以下简称“9号线”）清河路站—绿博园站区间为例，采用泡沫剂、膨润土及黏土作为改良剂，开展渣土改良试验，确定了每种改良剂和水的最佳配合比（质量比）；在此基础上采用单一改良剂和混合改良剂方案进行室内渣土改良搅拌试验、坍落度试验和渗透试验。明确了粉细砂层的渣土改良范围。以改良后的渣土坍落度为125~175 mm，渗透系数超过1×10-3 cm/s为控制指标，提出富水粉细砂层渣土改良方案。［结果及结论］单一改良剂优化试验中，巴斯夫泡沫剂质量分数建议为3%，钠基膨润土泥浆土水配合比宜为1∶9，黏土泥浆土水配合比宜为1∶5。单一改良剂在坍落度方面改善优异，使用黏土改良的渣土，具有更好的流塑性。混合改良剂的搅拌电流和渗透系数比单一改良剂要小，表明其在渣土的摩擦性和渗透性方面改善突出，其中泡沫剂与膨润土的配合比为2∶1的渣土改良方案较好。富水粉细砂层渣土改良方案为：泡沫剂改良方案下，泡沫剂的注入率为20%~30%；膨润土改良方案下，膨润土的注入率为15%~20%；黏土改良方案下，黏土的注入率为40%~45%；泡沫剂与膨润土的配合比为1∶1的改良方案下，改良剂的注入率为20%；泡沫剂与膨润土的配合比为2∶1的改良方案下，改良剂的注入率为20%；泡沫剂与黏土的配合比为1∶2的改良方案下，改良剂的注入率为20%~40%。
Abstracts:
［Objective］ During EPB (earth pressure balance) shield tunneling through the water-rich silty fine sand layers, the ground is characterized by high friction, poor flow plasticity, and strong permeability. These features necessitate slurry improvement to enhance construction safety. ［Method］ Taking the section between Qinghe Road Station and Green Expo Park Station of Nanjing Metro Line 9 (hereinafter referred to as ′Line 9′) as case study, improvement agents including foam, bentonite, and clay are used to conduct slurry modification experiments. Thus, the optimal mass ratios between each agent and water are determined. On this basis, laboratory tests—including mixing, slump, and permeability tests—are conducted using both individual and combined improvement agents to define applicable range of slurry improvement in silty fine sand layers. A slurry improvement plan for water-rich silty fine sand is proposed, with a target slump of 125-175 mm and a permeability coefficient exceeding 1×10-3 cm/s as control indicators. ［Result & Conclusion］ In the optimization tests of individual improvement agents, the recommended BASF foam content is 3% by mass, the bentonite-to-water mass ratio should be 1∶9, and the clay-to-water ratio be 1∶5. Individual agents significantly improve the slump performance, and slurry modified with clay show better flow plasticity. Mixed agents exhibited lower mixing current and permeability coefficient compared to single agents, indicating their superior improvement in reducing slurry friction and permeability. Among the combinations tested, a foam-to-bentonite ratio of 2∶1 yielded better performance. The recommended slurry improvement schemes for water-rich silty fine sand layers are as follows: foam-only improvement plan with foam injection rate of 20%-30%; bentonite-only improvement plan with bentonite injection rate of 15%-20%; clay-only improvement plan with clay injection rate of 40%-45%; foam-bentonite 1∶1 agent improvement plan with agent injection rate of 20%; foaming-bentonite 2∶1 agent improvement plan with agent injection rate of 20%; and foaming-clay 1∶2 agent improvement plan with agent injection rate of 20%-40%.
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