【作者】 刘杰；

【导师】 张晓西； 乌效鸣；

【作者基本信息】 中国地质大学 ， 地质工程， 2009， 硕士

【摘要】 随着西气东输工程的开展以及城市地下管网基础建设的发展,非开挖水平定向钻技术应用日趋广泛。在非开挖水平定向钻技术的广泛应用的同时,遭遇的工程实际情况也越来越复杂,克服这些工程难题也使非开挖水平定向钻技术越来越成熟。非开挖水平定向钻工程施工中,通过泥浆循环系统将钻头切削下来的碎岩屑从孔底排出至地表。由于地层存在天然的缺陷——孔隙和裂缝,泵入的泥浆通过地层的孔隙和裂缝形成的通道流出地表,这种现象就是冒浆。目前冒浆问题已成为阻碍非开挖水平定向钻技术发展的重要问题,其对于整个工程施工而言具有诸多坏处。(1)冒浆过程中泥浆通过钻孔孔壁渗入地层,改变了孔壁周围的岩土应力状况,严重影响孔壁的稳定性,增加了工程施工的风险;(2)冒浆使泥浆在穿越区域的地表流动,泥浆中往往有化学药品的成份,给地表的环境造成污染,对农田植被造成破坏;(3)冒浆情况严重时,改变冒浆区域土层的应力,导致土体破坏,对道路、建筑物、原有地下设施的安全带来了严重隐患;(4)冒浆发生后,钻进施工中耗费的泥浆量将会增大,增加了工程施工的原料消耗成本。非开挖水平定向钻工程领域的冒浆问题在近年来才得到关注,国内外学者的研究基本上是工程经验的初步总结。本文针对冒浆问题从以下几个方面进行了研究和探讨:(1)针对冒浆问题的渗透破坏模型针对冒浆问题,本文从渗流时间和渗流路径两个方面建立了模型,分别是:针对渗流过程的时间因子影响模型和针对地层破坏的路径影响因子模型。从时间因子影响模型的分析,得出在地层渗流的孔隙通道不被堵塞的情况下,冒浆发生所需要的时间与土层的渗透率成反比,与钻孔的水平埋深的3/2次方成正比,与泥浆的压力近似成正比。从路径影响因子模型的分析,得出在地层渗流的空隙通道被堵塞的情况下,冒浆发生的形势是破坏土层形成新渗流通道,此时冒浆取决于土层在不破坏的情况下的所能承受的最大压力与泥浆当前压力的比值,当泥浆压力大于土体破坏的临界压力时,冒浆就会发生。(2)室内冒浆实验通过对非开挖工程岩土颗粒特性和钻进泥浆粘土特性的分析,用砂粒作为渗流的岩土介质进行了室内的冒浆实验,确定了在非开挖水平定向钻工程中,泥浆的粘土粉加量、泥浆的添加剂含量以及岩土颗粒大小对渗透率产生影响。同时对于泥浆在土层中的封堵效果进行了模拟实验,分析得出:当岩土层孔隙当量直径小于20μm时,泥浆容易形成封堵:同时泥浆的添加剂可以提高形成封堵的岩土颗粒粒径值。(3)针对冒浆的泥浆设计从泥浆循环降压理论的分析结果可知,当调整泥浆各项性能参数时,泥浆在钻孔中的压力将会发生变化,而降低泥浆的压力可以防止冒浆的发生。本文从高剪稀释理论及实验、堵漏原理及配方优化和泥浆用水处理三个方面对泥浆设计做了实验研究,最后设计出针对冒浆的泥浆配方。(4)软件设计运用本文冒浆的理论以及防治冒浆措施中的泥浆设计手段,设计了一套以防冒浆为主要目的的泥浆设计软件。该软件主框架设计为MFC,能更好的与各种操作平台兼容,同时软件设计以操作简单、界面友好为原则,更利于用户使用。通过北运河穿越工程的现场试用,验证了该软件的可靠性和准确性。最后,本文对研究内容做了总结,得出相关的结论,并在此基础上,提出了针对非开挖水平定向钻工程中冒浆的进一步研究思路和建议。更多还原

【Abstract】 With the development of West-East Gas Pipeline project and the urban underground pipeline network infrastructure,Horizontal Directional Drilling(HDD) technology applications become more widespread.But the actual situation encountered by the project are more and more complex, which make HDD technology become more and more sophisticated to overcome these engineering problems along with HDD technology widely used at the same time.In HDD project,spoils can be removed to the ground surface through themud system.The pumped mud could flow to ground surface through pores and cracks which are natural defects of ground.That phenomenon is called mud escaping.The mud escaping was in the way of HDD development,and it was bad to HHD project as follow:(1)When mud escaping occurred,mud seeped into formation.So the stress of formation was changed that would be bad to borehole stability.(2)The mud escaping led to mud flowing on ground.Because there was chemistry component in the mud,it would pollute the environment and damage the farmland.(3)When mud escaping was severe,formation would be destroyed and it brought hidden trouble to roads,buildings and underground constructs.(4)the cost of project was increased as the mud escaping.The mud escaping of HDD was been attention recently and inside and outside scholar researched in the way of summarizing experience.This paper research the mud escaping basing on the follow:(1)Penetration damage model for the mud escapingFor the mud escaping,this article sets up two models according to the time and path of percolation respectively,which are:the model of time factor impacting on the percolation process and the model of path factor impacting on the formation damage.From the analysis of the time factor impacting model,under the condition of the percolation channel,which is formed of formation pore,has not been plugged,the time required for the mud escaping occurring is inversely proportional to the soil penetration,proportional to the power of 3/2 of the horizontal depth of borehole,and approximately proportional to the pressure of the mud.From the analysis of the path factor impacting model,the form of mud escaping occurring is forming new channels after damaging the soil formation under the condition of the percolation channel has been plugged. Whether the mud escaping occurs depends on the ratio of the greatest pressure which the soil formation bears and the pressure of the mud.The mud escaping occurs when the mud pressure is greater than the critical damage pressure of soil formation.(2)The mud escaping experimentThrough the analysis of properties of geotechnical particles and properties clay powder in HDD,we design mud escaping experiment using sand as medium,and conform that the proportion of clay powder in mud,additive content of mud and the size of formation particle has impact on permeability in HDD.We also design the plug experiment with mud,and get the conclusion:mud easily plugs the percolation channel of formation when the diameter of formation hole less than 20μm.In addition,mud additives could improve the diameter of formation hole which can be plugged by mud.(3)The design of mud for preventing mud escapingThrough the analytical result of mud circulating depressurizing theory,it can be known that after adjusting the mud performance parameters,the pressure of mud in the borehole will be changed,and pressure release of mud can prevent the occurrence of mud escaping.In this paper, experimental research has been done on mud design by means of three aspects which are high-shear dilution theory and experiment/plugging principle and formula optimization/treament of water for mud.As well as,mud formulations have been designed which could prevent the mud escaping occurring.(4) Software DesignBased on the theory of mud escaping and the mud design method of preventing mud escaping, we developed a mud design software,the main purpose of this software was to prevent mud escaping.The software’s main framework is MFC,which can be widely compatible with.The software is user-friendly and easy-operation.And it was used in the North Canal project,the results show that the software was reliability and accuracy.Finally,the study was summarized and some relevant conclusions were raised at the last of this paper,furthermore,the paper raised some ideas and advice for the further study.更多还原