Digital monitoring of rotary-percussive drilling with down-the-hole hammer for profiling weathered granitic ground

Rock and geotechnical engineering investigations involve drilling holes in ground with or without retrieving soil and rock samples to construct the subsurface ground profile.On the basis of an actual soil nailing drilling for a slope stability project in Hong Kong,this paper further develops the drilling process monitoring(DPM)method for digitally profiling the subsurface geomaterials of weathered granitic rocks using a compressed airflow driven percussive-rotary drilling machine with down-the-hole(DTH)hammer.Seven transducers are installed on the drilling machine and record the chuck displacement,DTH rotational speed,and five pressures from five compressed airflows in real-time series.The mechanism and operations of the drilling machine are elaborated in detail,which is essential for understanding and evaluating the drilling data.A MATLAB program is developed to automatically filter the recorded drilling data in time series and classify them into different drilling processes in sub-time series.These processes include penetration,push-in with or without rod,pull-back with or without rod,rod-tightening and rod-untightening.The drilling data are further reconstructed to plot the curve of drill-bit depth versus the net drilling time along each of the six drillholes.Each curve is found to contain multiple linear segments with a constant penetration rate,which implies a zone of homogenous geomaterial with different weathering grades.The effect from fluctuation of the applied pressures is evaluated quantitatively.Detailed analyses are presented for accurately assess and verify the underground profiling and strength in weathered granitic rock,which provided the basis of using DPM method to confidently assess drilling measurements to interpret the subsurface profile in real time.

Performance of large-diameter pneumatic down-the-hole (DTH) hammers: A focus on influences of the hammer structure

Pneumatic down-the-hole (DTH) hammer has been extensively used in air drillings through hard and ultra-hard geological formations. Numerical modeling can offer close observation on the working behaviors by visualizing internal pressure status as well as provide reliable performance predictions for large-diameter DTH hammers to which conventional empirical and experimental approaches cannot be applied. In this study, CFD simulations coupled with dynamic meshing are utilized to simulate the air flow and piston movement inside the large-diameter DTH hammers. The numerical modeling scheme is verified against a theoretical model published in literature. Effects of structural parameters on hammer performance, including piston mass, piston upper-end diameter, piston groove diameter, and lengths of intake and exhaust stroke in both front and rear chambers, are analyzed in detail by virtue of sets of numerical simulations. The simulations suggest that changing the intake stroke of front chamber has a negligible influence on hammer performance while increasing the piston groove would lower all the four indicators of hammer performance, including impact energy, impact frequency, maximum stroke, and air consumption rate. Changing the other structural parameters demonstrates mixed effects on the performance indicators. Based on the numerical simulations, a large GQ-400 DTH hammer has been designed for reduced air consumption rate and tested in a field drilling practice. The air drilling test with the designed hammer provided a penetration rate 1.7 times faster than that of conventional mud drilling.

Analysis of effects of operating parameters on rate of penetration in drilling process with air down-the-hole hammer

Air down-the-hole(DTH)hammer drilling has long been recognized to have the potential of drilling faster than conventional rotary drill,especially in some hard rocks such as granite,sandstone,limestone,dolomite,etc.with the same weight on bit(WOB)and rotations per minute(RPM).So,it has been widely used in many drilling fields including mineral resource exploration drilling,oil and gas drilling and geothermal drilling.In order to reduce drilling cost by selecting optimal drilling parameters,rate of penetration(ROP)should be estimated accurately and the effects of different factors on ROP should be analyzed.In this research,ANN model with several multi-layer perception back propagation(BP)networks for predicting ROP of air DTH hammer drilling was developed using controllable parameters such as impact energy,impact frequency,WOB,RPM and bit operating time for the formations with a certain drillability index of rock.Several BP neural networks with the different neurons in hidden layers were developed and compared for selecting optimal architecture of ANN.The effects of the drilling parameters such as impact energy,impacting frequency,WOB,RPM and bit operating time on the ROP of air DTH hammer drilling were investigated by trained ANN.From the analyses,the optimum range of drilling parameters for providing high ROP were determined and analyzed for a formation with a certain drillability index of rock.The methodology proposed in this study can be used in many mathematical problems for optimization of drilling process with air DTH hammer.

Numerical solution for dynamics of pneumatic DTH hammer system

The pneumatic down-the-hole(DTH) hammer is one of the efficient equipments used in medium hard to very hard rock drilling frield,and any change in its structure design affects all performance parameters of a pneuamtic DTH hammer directly.Yet,owing to the complexity of the dynamic interaction among the components in DTH hammer systems,until now it has been difficult to obtain reliable estimates of the design parameter affects.Thus providing an design parameter optimization and the layout of dynamics behavior of DTH hammer is of great importance.This paper documents the development and solution of a computational model for the dynamic response of a pneumatic DTH hammer.The model consists of rigid piston dynamics equation and chamber thermodynamics equations.The resulting model represented by a set of coupled nonlinear differential equations were computed in Visual C++ program.The developed solutions are used to perform a parametric study to illustrate the inffluence of the piston mass and supply pressure on the impact performance of DTH hammer system.

Reverse Circulation DTH Hammer Drilling Technique

The technical characteristics and operational principal of the reverse circulation DTH hammer drilling technology is integrated introduced in this paper. Using simulation technology to assist the drilling tool design, the optimum designed DTH hammer gets stable performance, and the bit has reverse circulation ability, and further more, it has already developed serial products. The reverse circulation DTH hammer drilling technique has been fully applied in field such as the geological core exploration in complex strata, water well drilling, and large diameter rock embedding piles drilling in hard rock, and obviously, it is achieved favorable economic and social benefits.

FGC-15D large-diameter DTH air hammer drilling system and its application in offshore rock-socketed pile hole drilling

In the past two decades, numerous large-diameter rock-socketed piles were constructed in China to support foundations of skyscrapers, great bridges or to retain soil in potential geological hazard areas. However, drilling large-diameter rock-socketed pile holes with conventional drilling method such as rotary drilling or cable tool drilling is time-consuming and the cost is usually very high. In order to drill large-diameter rocksocketed pile holes faster at relatively low cost, the FGC15A large-diameter DTH air hammer drilling system was developed in 1987 and was given the second-clasa award by Ministry of Geology and Mineral Resources in 1991. Since it was innovated the drilling system has been used in more than twenty important and tough pro- jects on land, and wonderful results were acquired. At the same time the large-diameter DTH air hammer drilling system was improved continuously. The FGC15D is the latest version of the technique.

Air flow calculation of reverse circulation drilling technique with air DTH hammer

Air DTH hammer has been successfully applied in minor-caliber solid mineral exploration,water-well drilling and other drilling areas. In order to expand the applications of the technology,the authors further studied the principle and analyzed the mechanism of reverse circulation drilling technique with air DTH hammer to get the perfect assembles of equipments by optimizing working parameters. No parameter seemed more important than the air volume because it could maintain the working performance stability. The minimum air volume is related to the parameters such as depth and pressure,which was calculated under the actual conditions. It was solved for the air injection flow tables of the air DTH Hammer working at the different pressures. According to the data tables,operators could adjust the air volume to meet the demand on this technique,which had a realistic guiding significance. So it could build up a set of systematic and complete hi-technique.

Study on drilling mechanism and optimization of percussion-extruding DTH hammer bit

The authors tested the percussion-extruding Down-the-hole(DTH)hammer bit with five different structures and mainly analyzed the drilling mechanism between conical bit and stepped bit.In addition,aiming at "the pile effect" in combination with the advantage of stepped bit,we design a new cam spinning bit and test it outdoors.The result shows that using cam spinning bit can solve the problem of "the pile effect",which can also obtain higher drilling efficiency than using conical bit in high confining pressure strata.It is characterized by novel structure and high drilling speed as well as good guiding,and it is significant for improving efficiency in percussion-extruding drilling technique.

钻井利器的故事之“液动潜孔锤”

在各种钻探方法中,液动冲击回转钻进具有效率高、质量好、回次长、事故少、成本低等优点,而液动潜孔锤又是液动冲击回转钻进的技术核心。本文梳理了各种液动潜孔锤的结构特点及其与绳索取心钻具、孔底动力钻具相结合衍生的各种钻具,简要介绍了这一技术的典型应用案例,总结归纳了其下一步发展方向和技术难点,以期普及液动锤的应用,促进液动冲击回转钻进技术的进步。

气动潜孔锤在港口超厚抛石层中引孔沉桩的应用

气动潜孔锤钻孔具有施工速度快、功效高、质量可靠、性价比高,以及设备占地面积小、绿色环保无泥浆等特点,尤其适用于在超厚岩层的区域钻孔,但在港口工程领域应用较少。某石化码头工程引堤管架基础工程采用传统的冲孔灌注桩方案,施工效率非常低,无法如期保质完成。创新性地引入长螺旋气动潜孔锤辅助PHC桩沉桩的施工工艺,将原来的29个月施工时间缩短为2.5个月,极大提高了沉桩效率,满足工程总体进度要求;同时降低材料费、施工费,有效解决了工程难题,保证工程顺利按期完工。

生态库区超厚硬岩条件下大直径长桩桩基施工关键技术

针对生态库区超厚硬岩条件桥梁大直径长桩相对复杂的施工环境,常规施工工艺易造成环境污染、硬岩地层钻进速度慢、维护费用高。为了保护环境也方便施工,提出一种桩基新型施工技术,通过潜孔锤和旋挖钻结合,高效快速完成桩基施工且绿色环保。依托工程实例,对相关施工工艺进行详细阐述。

基于ABAQUS的气动潜孔锤球齿碎岩及布齿优化

为提高坚硬地层大直径潜孔锤的破岩效率与使用寿命,运用ABAQUS软件建立了球齿碎岩仿真模型,对比分析?18 mm球齿在不同钻进参数下冲击切削碎岩过程中的破碎比功、侵入深度、破碎范围与应力影响范围等曲线,优选钻进参数和布齿。分析结果表明:当钻压为1.2 kN、冲击功为30 J时,对岩石的破碎效率较高,球齿入岩的位移可达0.67 mm,并对岩石进行应力界限划分,得出应力影响范围为43.4 mm;通过双齿冲击切削模拟确定了较为优秀的圈距与间距:圈距取47.4 mm,间距取43.4~51.4 mm;考虑到球齿的磨损,利用圈距与间距对?711 mm大直径潜孔锤进行了优化布齿。

破碎带⁃硬岩复杂地层桩基成孔技术研究与应用

破碎带⁃硬岩地层具有破碎带层岩土体稳定性差,硬岩层强度高的特点。为解决破碎带⁃硬岩复杂地层桩基成孔问题,提出了旋挖引孔、潜孔锤凿岩的分层成孔技术,结合潜孔锤强大的破碎能力,并引入旋挖跟进护筒穿透破碎岩层,充分发挥了各自工艺的优势。以北京市西山南麓大直径桩基础工程为例,阐述了空压机风量、风压以及潜孔锤机械配置、钻进规程以及钻进效率等重要施工参数,总结分析了潜孔锤成孔过程中常见问题及原因,提出了相应的处理办法。旋挖⁃潜孔锤分层成孔技术有效提高了钻进效率和成孔质量,为复杂岩层桩基成孔技术提供一定的理论基础和实践经验。

潜孔锤引孔在水上厚抛石层PHC沉桩中的应用

针对斜坡式抛石结构引堤上PHC管桩在沉桩过程中难以穿透厚抛石层的问题,以某综合管架工程为例,进行施工工艺实践研究。在对常规引孔工艺进行对比的基础上,提出潜孔锤先引孔再施打预应力混凝土管桩的解决方案,并简要介绍了潜孔锤引孔设备及技术参数、施工工艺流程、引孔过程中存在的问题及相应解决措施。应用结果表明,采用潜孔锤引孔后的预应力混凝土管桩能高效贯穿抛石结构层,沉桩后桩身结构完整性好,单桩竖向承载力满足设计要求,该工艺切实可行。研究成果可为类似地基沉桩施工提供参考。

硬岩地层微型钢管桩抑尘降噪绿色施工技术研究

硬岩地层微型钢管桩施工过程中,通常采用气动潜孔锤作为成孔设备,易产生较大的噪音及扬尘,尤其对于在闹市区施工的地铁作业,不利于安全文明施工,导致投诉、信访等相关负面影响产生。通过在钻机孔口位置加装大功率吸尘器进行钻渣、岩屑及粉尘收集,能有效降低空气中粉尘浓度,实现扬尘控制;采用声屏障材料制作隔音屏,使用新型带消音装置的空压机,从根源及传播途径上双重控制噪音传播,有效减小噪音对环境的污染。通过现场验证及周边调查走访,扬尘及噪音已不是制约现场钢管桩施工的因素,实现微型钢管桩成孔过程的抑尘降噪绿色施工。

空气潜孔锤钻进技术在充填钻孔施工中的应用

在矿山开采的过程中,充填钻孔是主要构成充填体系的部分,利用矿山固体废弃物充填是实现尾矿、废石等消纳和处理的最有效方法,可以降低尾砂库面积、减轻尾砂库安全危害和社会经济负担,从而产生了可观的环保价值和效益。然而,矿山充填钻孔设计存在口径大、深度大、成孔垂直率高等特征,导致施工难度大大增加,有必要针对充填钻孔施工关键技术开展深层次的研究,保证矿山充填钻孔施工质量全面提高。本文以河北某铁矿区充填钻孔施工为例,系统研究了在充填钻孔施工中空气潜孔锤钻进装置选型配置、钻井参数的设定和冲击器的维护和保养等;探讨了空气潜孔锤钻技术在充填钻孔中的实际应用效果,以期促进对该技术在同类钻孔中的推广应用。

空气锤在石油钻井中的应用前景

针对目前深部、复杂地层钻速低和易产生井斜、大直径井眼和水平井施加钻压困难、钻井成本高等问题进行了大量的调研。通过相关文献提供的数据和图表资料分析得出:空气锤结合了冲击回转钻井和空气钻井的两大钻井优势,转速低,扭矩小,钻压小,降低了钻具循环应力和磨损,控制井斜容易,在很大程度上提高了机械钻速、降低了钻井时间和成本,钻硬地层时优点更为突出,由此提出了研究空气锤的必要性,并全面总结了空气锤钻井的优越性,同时也指出了它应用的局限性。最后分析了我国油气资源现状、钻井状况和空气锤在国内外的应用实例,得出空气锤在低压低渗层欠平衡钻井、欠平衡钻水平井、深井、超深井、复杂地层、大直径井中开发油气资源有着广泛地应用前景。

油气勘探钻井用液动射流式冲击器的研究与应用

冲击回转钻进技术是当前解决硬岩钻进难题最有效的方法之一，将液动冲击回转钻进技术成功地推广应用于油气田勘探钻井中，预期可使硬岩平均钻进效率提高３０％～５０％，成本下降１５％～２０％。笔者就液动射流式冲击器应用于石油钻井的可行性和意义进行了较详细的分析论证，对所设计的石油钻井用液动射流式冲击器的结构和工作原理进行了说明，最后总结了生产性试验中存在的问题，提出了进一步改进的方案。

贵州碎屑岩层地热深井空气潜孔锤钻进技术应用研究

本文研究了空气潜孔锤钻井技术在贵州省复杂碎屑岩层地热深井中的应用,涉及结构复杂、软硬互层、软弱夹层多及强水敏性泥页岩地层的56-1029m井段和Φ216-Φ315mm井径的条件,探讨了在这样环境下空气潜孔锤钻进设备机具配置组合、钻进参数;分析了深井碎屑岩层复杂井况的空气潜孔锤钻进效率。结果表明,该设备钻速是牙轮钻进的12.4-35倍,综合成本为198.73-693.93元/米,比牙轮钻进850-950元/米低得多。从复杂碎屑岩的结构特征和空气潜孔锤钻进特性,剖析了钻进中常遇问题的原因,并总结了相应的钻进技术和工艺措施。研究结果表明,合理设备机具的组合配置和钻进工艺措施能有效提高复杂碎屑岩层条件下空气潜孔锤钻进施工效率。

泡沫潜孔锤应用于水文水井钻探的钻进工艺初探

泡沫潜孔锤是将普通潜孔锤的工作介质从单一流体(空气)变成两相流体的压缩泡沫,并以泡沫作为动力介质驱动潜孔锤工作的新型工艺方法。从分析泡沫潜孔锤的结构特点和工作原理出发,结合室内实验,在钻进设备的配套、灌注系统的设计、钻进规程参数的选择等方面,对泡沫潜孔锤应用于水文水井钻探的钻进工艺进行了研究。结果表明,泡沫潜孔锤钻进技术有着广泛的应用前景。