ESR and U-series ages of coral reef samples from shallow drill holes in the South China Sea

The ages of coral reef samples from several shallow drill holes in the South China Sea are determined by ESR and U-series (230Th/234U) methods. The experimental results show ideal agreement between ESR and U-series ages and that the coral reefs were formed in the early Holocene. In the determination of natural total dose of coral reef by use of the additive dose method good results can be obtained by exponential fitting, no matter how the effect of dose saturation is. It was found that the ratio of the natural ESR signal intensity ( I0) to the ESR signal intensity at dose saturation ( Imax) of sample can reflect the significance of a irradiation efficiency-k value. Using the k value of sample determined by the formula given in this paper, the precision of ESR dating of marine carbonates can be improved.

Research on the Effects of the Contents of Radioactive Elements on Granularity and Climate Change:An Example of SZK1 and SZK2 Drill Holes Strata in the Fuzhou Basin

Based on the content of radioactive elements (U, Th, K) of strata in two drill holes in the Fuzhou basin, and combined with the result of spore_pollen analysis, the relationship between radioactivity and lithology and deposit environments is discussed and the results show that the content of radioactive substances is related to the granularity and lithology in sediment, and it is higher in argillaceous sediment (e.g. silt and clay), lower in sand sediment and in the middle in gravels between the above two kinds of sediment. The content of radioactive substances is also related to paleoclimate. A warm and humid environment is propitious to the deposition of radioactive substances, while a cool and dry climate is just the reverse.

Crack stop holes in steel bridge decks:Drilling method and effects

Force analysis using a compact tension model, as recommended by ASTM, was carried out on a crack stop hole. The stress before, and after, drilling the hole was compared in terms of stress concentration and stress gradient. The optimum drilling location and diameter were studied through analysis of different locations and diameters. By analyzing the effects of flank holes and an additional hole, drilling advice was proposed and fatigue testing of the cracks in a steel bridge deck with a crack stop hole was conducted. The results show that the stress at the crack tip with a crack stop hole decreased, and the major principal stress around the hole was distributed accordingly. The optimum position of the crack stop hole centre was where the centre of the crack stop hole was situated behind the crack and the hole edge coincided with the crack tip. Therefore, hole diameters larger than 8 mm, or those weakening the section by 10%, were suggested as the best diameters. In terms of multi-hole crack stopping, a flank hole was not recommended. The optimum horizontal position of flank holes was at a distance of 1/4 of a single hole diameter from, and in front of, the single hole. Besides, the experiment showed that crack stop hole could only prevent cracks from growing and had no influence on crack growth rate.

Stability and nonlinear dynamic behavior of drilling shaft system in copper stave deep hole drilling

The stability and nonlinear dynamic behavior of drilling shaft system in copper stave deep hole drilling were analyzed. The effects of the fluctuation of the cutting force, the mass eccentricity and the hydrodynamic forces of cutting fluid could be taken into consideration in the model of drilling shaft system. Based on the isoparametric finite element method, the variational form of Reynolds equation in hydrodynamic fluid was used to calculate nonlinear hydrodynamic forces and their Jacobian matrices simultaneously. In the stability analysis, a new shooting method for rapidly determining the periodic orbit of the nonlinear drilling shaft system and its period was presented by rebuilding the traditional shooting method and changing the time scale. Through the combination of theories with experiment, the correctness and effectiveness of the above methods are verified by using the Floquet theory. The results show that the mass eccentricity can inhibit the whirling motion of drilling shaft to some extent.

Hole-drilling method using grating rosette and Moire interferometry

The hole-drilling method is one of the most wellknown methods for measuring residual stresses. To identify unknown plane stresses in a specimen, a circular hole is first drilled in the infinite plate under plane stress, then the strains resulting from the hole drilling is measured. The strains may be acquired from interpreting the Moire signature around the hole. In crossed grating Moire interferometry, the horizontal and vertical displacement fields （u and v） can be obtained to determinate two strain fields and one shearing strain field. In this paper, by means of Moire interferometry and three directions grating （grating rosette） developed by the authors, three displacement fields （u, v and s） are obtained to acquire three strain fields. As a practical application, the hole-drilling method is adopted to measure the relief strains for aluminum and fiber reinforced composite. It is a step by step method; in each step a single laminate or equivalent depth is drilled to find some relationships between the drilling depth and the residual strains relieved in the fiber reinforced composite materials.

Hole Cleaning Prediction in Foam Drilling Using Artificial Neural Network and Multiple Linear Regression

Foam drilling is increasingly used to develop low pressure reservoirs or highly depleted mature reservoirs because of minimizing the formation damage and potential hazardous drilling problems. Prediction of the cuttings concentration in the wellbore annulus as a function of operational drilling parameters such as wellbore geometry, pumping rate, drilling fluid rheology and density and maximum drilling rate is very important for optimizing these parameters. This paper describes a simple and more reliable artificial neural network (ANN) method and multiple linear regression (MLR) to predict cuttings concentration during foam drilling operation. This model is applicable for various borehole conditions using some critical parameters associated with foam velocity, foam quality, hole geometry, subsurface condition (pressure and temperature) and pipe rotation. The average absolute percent relative error (AAPE) between the experimental cuttings concentration and ANN model is less than 6%, and using MLR, AAPE is less than 9%. A comparison of the ANN and mechanistic model was done. The AAPE values for all datasets in this study were 3.2%, 8.5% and 10.3% for ANN model, MLR model and mechanistic model respectively. The results show high ability of ANN in prediction with respect to statistical methods.

Residual Stress Measurement for Ion-implanted NiTi Alloy by Using Moiré Interferometry and Hole-drilling Combined Method

Residual stresses in ion-implanted NiTi alloy are measured by a combined method ofMoir6 interferometry and hole-drilling. Oxygen ions are implanted into the NiTi alloy under a voltage of 30 kV by a dose of 1.0×10^17ions/cm^2 for one hour. Subsequently, in order to avoid dimensional error, a hole is drilled exactly in the center of the sample. The distribution of residual stresses around the hole is measured. It is indicated that the method which combines the Moire interferometry with hole-drilling is able to be used to measure residual stresses produced by ion implantation.

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.

Exploration and determination of the principles of rotary-percussive underground slimhole drilling

A possibility of the efficient use of rotary percussive drilling to provide drilling smaller diameter holes(40–70 mm) both in mining and prospecting is disclosed herein. A new construction designed for the nipple thread connection is described. The relative amplitude variation, change of power pulse time and energy in their propagation throughout the drilling tool are determined. A possibility of the efficient power pulse transfer along the drill string to the rock destruction tools with new nipple connections which allow automating the make-up and breakout system of drill pipe was supported by experiments.

Influence of friction on buckling of a drill string in the circular channel of a bore hole

Enhancement of technology and techniques for drilling deep directed oil and gas bore hole is one of the most important problems of the current petroleum industry.Not infrequently, the drilling of these bore holes is attended by occurrence of extraordinary situations associated with technical accidents. Among these is the Eulerian loss of stability of a drill string in the channel of a curvilinear bore hole. Methods of computer simulation should play a dominant role in prediction of these states. In this paper, a new statement of the problem of critical buckling of the drill strings in 3D curvilinear bore holes is proposed. It is based on combined use of the theory of curvilinear elastic rods, Eulerian theory of stability, theory of channel surfaces, and methods of classical mechanics of systems with nonlinear constraints. It is noted that the stated problem is singularly perturbed and its solutions have the shapes of localized harmonic wavelets. The calculation results showed that the friction effects lead to essential redistribution of internal axial forces, as well as changing the eigenmode shapes and sites of their localization. These features make the buckling phenomena less predictable and raise the role of computer simulation of these effects.

Permittivity of composites used for Luneburg lens antennas by drilling holes based on 3-D printing technique

Due to the attractive performances such as the ability of beam focus,broadband,multi-beam scanning and other features,Luneburg lens antennas are applied in multi-beam antenna,which overcomes the problem of gain loss produced by multi-beam parabolic antenna.Based on 3-D printing technique,Luneburg lens antennas by drilling holes are studied.Permittivity and loss tangent of the equivalent lens materials can be influenced by original materials,hole shapes,hole directions,and porosity.After tests,polystyrene with waxes may be the most appropriate materials for Luneburg lens with high strength.Permittivity with the shape of triangle is the lowest due to the homogeneity.Relative permittivities with the direction at a range of 15°-45°are lower while loss tangent at a range of 0°-30°.Radial directional holes are more appropriate for Luneburg lens.The relative permittivity is decreased with the increment of porosity.After calculations,the forecasts calculated by Looyenga and A-BG theory are more precise.Finally,Luneburg lens with two layers is fabricated by 3-D printing.

Study on Plasticity Modification for Measuring High Residual Stress by Hole-Drilling Method

Hole-drilling method is a commonly used method for measuring residual stress. The calibration coefficients in ASTM E837-13 a would cause large errors due to the plasticity deformation of materials. In the study, calibration coefficients were modified in the plasticity deformation stage based on the distortion energy theory. The calibration experiment of calibration coefficients was simulated by the finite element model, and the plasticity modification formulas of 7075 aluminum alloy were obtained. From the results of uniaxial tensile loading test, the measuring errors of high residual stress are significantly reduced from-4.071%～53.440% to-5.140% ～ 0.609% after the plasticity modification. This work provides an effective way to expand the application of hole-drilling method.

Micro Electrical Discharge Machining(μEDM):Holes Drilling and Characterization of the Process Parameters

μEDM(micro-electrical discharge machining)is a process for machining conductive materials without mechanical contact;it is particularly suitable for machining hard materials.The principle consists in creating electrical discharges between a micro-tool and a workpiece,both of which are immersed in a dielectric.It is a complementary process to mechanical,laser,micro-machining techniques,and even to techniques derived from silicon microtechnology(RIE,DRIE,LIGA).However,the resolution ofμEDM is limited;it depends on several electrical and physical parameters.The goal of this paper is to characterize the holes obtained by drilling usingμEDM with different micro-tool diameters(Φ=250μm;Φ=80μm;Φ=40μm;Φ=20μm)for an experimental time of t=2 h.The results obtained let us conclude that a large diameter micro-tool(Φ=250μm)leads to removing a larger amount of material(43×10^(5)μm^(3))than small diameters:Φ=80μm;Φ=40μm;Φ=20μm where the removed volume is equal to 2.6×10^(5)μm^(3);105μm^(3);0.4×10^(5)μm^(3),respectively.The electrode-tool diameter influences the maximum depth of the holes;a diameter ofΦ=250μm generates a hole where the maximum depth is 170μm while small diameters:Φ=80μm;Φ=40μm;Φ=20μm provide holes with a depth of 82μm;51μm;50μm respectively.Through these experiments,we can also conclude that the lateral gap of the holes is almost constant.It is about 40μm whatever the diameter.

Automatic Modification of Local Drilling Holes via Double Pre-Assembly Holes

Manufacturing accuracy, especially position accuracy of fastener holes, directly affects service life and security of aircraft. The traditional modification has poor robustness, while the modification based on laser tracker costs too much. To improve the relative position accuracy of aircraft assembly drilling, and ensure the hole-edge distance requirement, a method was presented to modify the coordinates of drilling holes. Based on online inspecting two positions of pre-assembly holes and their theoretical coordinates, the spatial coordinate transformation matrix of modification could be calculated. Thus the straight drilling holes could be modified. The method improves relative position accuracy of drilling on simple structure effectively. And it reduces the requirement of absolute position accuracy and the cost of position modification. And the process technician also can use this method to decide the position accuracy of different pre-assembly holes based on the accuracy requirement of assembly holes.

煤矿防冲钻孔机器人全自主钻进系统关键技术

针对高地应力矿井钻孔卸压作业智能化程度低的技术难题,总结分析了国内外钻孔卸压技术和装备的研究现状,指出研发高性能、高可靠、高效率的防冲钻孔机器人全自主钻进系统是破解冲击地压防治难题的重要发展方向。为此,凝练了影响钻进系统性能的“孔位精准识别、钻具姿态精确感知、无线电磁随钻智能检测、钻具运行状态智能识别和钻进系统精确控制”五大关键技术,并给出了解决思路和方法。针对在复杂恶劣环境下卸压孔的精确识别问题,设计了融合图像尺寸调节和多阶段训练模式的卸压孔图像样本扩充SinGAN模型,引入多层特征融合优化的FasterRCNN,构建了基于改进SqueezeNet轻量级网络架构的孔位识别模型,以实现卸压孔位的准确快速识别;针对钻具姿态精确感知问题,提出了基于改进梯度下降法算法优化无迹卡尔曼滤波的惯性测量单元(Inertial Measurement Unit,IMU)初始对准方法,设计了多个IMU的空间阵列布局方式,研究了基于BP神经网络的钻具姿态误差补偿方法,旨在提高钻具姿态的解算精度,实现精准钻孔卸压;针对复杂地质环境下钻进工况的精确检测问题,搭建了煤矿井下随钻测量无线电磁传输系统架构,探讨了微弱电磁波信号自适应调制和随钻高速双向电磁传输技术原理,研究了孔底地质参数、几何参数和工程参数的测量原理和实现过程;针对钻进系统运行状态识别问题,构建了钻进信号时域、频域、时频域的多域特征和深度网络高级特征提取架构,提出了钻进系统关键零部件健康状态评估和故障诊断技术,构建了基于改进蝙蝠优化长短期记忆网络的卡钻风险因子预测模型,实现对卸压钻具卡钻状态的准确预测;针对钻进系统的精确控制问题,分析了钻进系统的液压系统工作原理,构建了考虑煤岩性状的钻进系统精确控制方案,探讨了基于转矩和位置的钻进系统最优控制参数求解原理,旨在实现钻进回转系统和给进系统的智能协同控制和并行作业。

坦桑尼亚恩泽加地区覆盖区选区评价及综合找矿方法研究

恩泽加(Nzega)绿岩带为坦桑尼亚环维多利亚湖八大绿岩带之一,为坦桑尼亚重要的产金区域之一。由于其地表覆盖程度较高,地质调查和勘查工作程度较低,虽然针对隐伏型金矿床尚具备一定的找矿潜力,但同时也面临选区评价和找矿困难的问题。研究表明:在选区评价中,针对太古界尼安萨群条带状铁建造的区域航磁异常解译和研究区地球化学金异常分析是最主要的;而在采用地物化综合找矿方法开展勘查工作中,磁法和激电法结合对于寻找覆盖区下的含铁建造内部或接触带附近或剪切带内的金矿床效果较好。该地区首次使用了取样钻施工采样,对覆盖层下发育的含金矿化蚀变带进行了地质工程揭露,取得了一定的找矿成果,先后发现了伊博罗格罗(Iborogo)、卢素(Lusu)和乔马(Choma)等多个金矿床(点)。

车用CFRP材料超声振动钻孔工艺优化及质量分析

为了提高难加工增强体碳纤维复合材料(CFRP)的钻孔加工性能,在螺旋铣加基础上增加了超声振动辅助。设计了不同工艺条件对CFRP超声振动螺旋铣孔实施测试,对比了各条件下CFRP超声辅助螺旋铣孔的切削力差异,测试了孔加工质量状态。研究结果表明:采用超声振动螺旋铣方法处理可以避免引起分层现象,保证同一部位纤维与树脂基体相互形成更紧密结构。综合工艺参数对切削力和切削温度的影响,确定一下参数范围是比较优秀的:主轴转速4000r/min,螺距0.15mm,切向进给量0.04mm。CFRP分层状态受到切削刃锋利性以及材料去除率的综合影响,调整工艺参数能够有效的控制材料去除量,对切削力和切削温度起到很好的调节效果,进而减小分层损伤。

STUDY ON THE ON－LINE OPTIMAL CONTROL OF PARAMETERS OF THREE－CONE BLAST HOLE DRILLS

A model recognition method for the on-line optimal control of the parameters ofthree-cone blast drills is developed. It takes a few of on-line measurements and has a rapidoptimization speed. The mathematic model for on-line optimal control of the parameters and thedetermination of the parameters in the model are also presented.

岩心钻探振动拔管器的研制及在卡埋钻处理中的应用

卡埋钻事故是矿产资源勘查岩心钻探最难处理的事故,传统的强拉、强顶、强扭、反丝钻杆反取等处理方式,处理成功率均极低,且程序繁琐,耗时、耗力、耗成本。为解决卡埋钻事故处理难题,研制了振动拔管器。使用时,将该机具安装在孔口钻杆上,通电即产生高频高压振动,然后用钻机主卷扬向上提拉振动拔管器+钻杆连合体,通过提拔+振动联合作用,实现解除卡阻。振动拔管器坚固耐用、操作方便、成本低廉,在钻探现场应用处理卡埋钻事故数十次,成功率达90%以上,具有极大的推广应用价值。

GFRP/Al叠层材料钻削力与制孔质量的实验研究

复合材料与金属组成的叠层结构已在航空航天领域广泛使用,然而在复合材料/金属叠层结构上钻削高质量的孔仍是一个挑战。本文旨在研究钻削工艺参数对GFRP/Al叠层材料钻削轴向力和制孔表面质量的影响。使用普通硬质合金麻花钻对GFRP/Al叠层材料进行“一次性”钻孔,并通过Kistler测力仪测量钻削轴向力。结果表明,最大钻削轴向力随每转进给量增加几乎线性增加,随主轴转速增加小幅降低。钻削工艺参数影响铝合金和GFRP制孔表面质量,高每转进给量会降低铝合金制孔出口毛刺,但是会增加GFRP制孔出口损伤;高主轴转速会增加铝合金制孔出口毛刺和GFRP制孔出口损伤。与每转进给量相比,主轴转速对铝合金和GFRP制孔质量影响更大。