导　　师： 夏柏如;周与诚

学科专业： 081803

授予学位： 硕士

作　　者： ;

机构地区： 中国地质大学北京

摘　　要： 北京的地下水超采问题一直为人们关注，从上世纪末至今北京地区的地下水水位以每年1.2m的速度下降，导致了缺水问题日益突出。在这种背景下，北京近几年开始采取更严格的监管手段来限制降水，并鼓励采用止水、隔水办法。根据北京地区的地质情况，在已有技术的基础上探索出一种效果良好的止水措施势在必行。本文研究的长螺旋搅喷技术即为一种积极地探索，长螺旋搅喷技术将深层搅拌技术和高压喷射技术结合起来，用长螺旋钻机成孔，成孔后通过设置在钻头最外缘的喷嘴来喷射高压浆液，切削破坏周围土体，剥落下的土屑与浆液在钻具的搅拌作用下均匀混合，多余的泥浆被排出孔外，最终形成水泥土桩。这种长螺旋搅喷桩应用于基坑工程止水帷幕的止水效果良好，可获得很好效益。 本文首先总结国内外深层搅拌技术和高压喷射注浆技术的发展历史，研究长螺旋搅喷技术中喷射作用的理论基础，从理论角度对影响高压喷射射流的各种因素予以阐明，分析了长螺旋搅喷技术应用于北京地区的优势，并结合现场试验来检验长螺旋搅喷技术在硬质土层条件下成桩直径的可靠性，说明钻杆提速、喷射次数和土质的不同对成桩效果的影响。其次，介绍长螺旋搅喷技术在北京来广营乡一基坑工程中实施的具体情况，现场止水效果良好，满足设计要求。最后，提出长螺旋搅喷技术在施工工艺、工艺参数选择上需要改进的建议和措施。 根据本文研究，与深层搅拌法和高压喷射法相比，长螺旋搅喷技术具有成桩直径大、成本低、排出废浆量少、施工简单等优势。长螺旋搅喷搅喷技术的射流切削长度随土层粘聚力增大而减小；切削长度随提速的提高而减小，但当喷射次数增加时，提速的变化对射流切削长度的影响变小；切削长度随喷射次数的增加而增大。射流在定喷时切削长度大于在旋喷时的切削长度，但在较硬的粘土层中，降低转速不能显著增加射流切削长度喷；在粉土层中降低转速能显著增加切削长度。 该技术在北京地区具有较大的发展前景，是一项值得继续深入研究和推广使用的止水技术。 People have been paying attention to the excessive groundwater exploitation inBeijing. Beijing’s groundwater level has been dropping by1.2meter per year since theend of last century. Water scarcity problem is becoming increasingly acute. In thiscontext, Beijing has begun to take more stringent regulatory measures to limitdewatering, and to encourage using water-proof measures in recent years.Accordingto the geological condition of Beijing, to explore a good water-proof curtain measureis imperative. The technology of long spiral mixing jet grouting we study in this paperis a kind of the measures which we actively explore. The technology of long spiralmixing jet grouting combinesdeep mixing technology with jet grouting technology. Inthis process, long spiral machine is used to drill a hole, nozzles which are installed inthe outer edge of the blade is for injecting slurry, and then surrounding soil is cut bythe slurry. Finally, the blades mix the cutting soil with slurry together into awhole-cement-soil pile. It gets good benefits to use long spiral mixing jet groutingpile as foundation engineering water-proof curtain. Firstly, this paper presents the development of deeply mixing technology and jetgrouting technology, studies the theoretical basis of injecting, and clarifies variousinfluence factors of jet grouting. Besides, the article analyses the advantages whenlong spiral mixing jet grouting pile is used in Beijing, verifies the reliability of the pilediameter depended on field test, and explains how lifting speed、injecting times anddifference of soil influence on piling results. Secondly, the paper introduces anapplication example in Laiguangying town in Beijing, and finally puts forwardsuggestion and means about construction parameters and the technique of long spiralmixing jet grouting. According to the study, it has great advantage to use the technology of long spiralmixing jet grouting compared with deeply mixing technology and jet groutingtechnology.Its pile diameter is larger, the cost is lower, the construction is not onlysimple but also efficient. This technology has great application prospects in Beijing. It is worthy of furtherstudy and promoting.

关 键 词： 长螺旋搅喷 高压射流 现场试验 工艺参数 水泥土桩

分 类 号： [P641.8]

领　　域： [天文地球] [天文地球]