Investigating the influence of delamination on the stiffness of composite pipes under compressive transverse loading using cohesive zone method

The effect of delamination on the stiffness reduction of composite pipes is studied in this research. The stiffness test of filament wound composite pipes is simulated using cohesive zone method. The modeling is accomplished to study the effect of the geometrical parameters including delamination size and its position with respect to loading direction on stiffness of the composite pipes. At first, finite element results for stiffness test of a perfect pipe without delamination are validated with the experimental results according to ASTM D2412. It is seen that the finite element results agree well with experimental results. Then the finite element model is developed for composite pips with delaminated areas with different primary shapes. Thus, the effect of the size of delaminated region on longitudinal and tangential directions and also its orientation with respect to loading direction on delamination propagation and stiffness reduction of the pipes is assessed.     

旋挖钻机在大直径深孔钻孔桩中的应用

主要以南京大胜关长江大桥北引桥钻孔灌注桩施工为例进行总结,介绍了旋挖钻机在地质条件复杂的情况下对大直径、深孔钻孔桩的施工方法,主要从施工准备、钻孔、清孔等几个方面进行了论述,从而推广旋挖钻机的应用。     

钻探凿井中常见问题的预防及处理

对钻探凿井中常见的问题如钻孔弯曲、卡钻、夹钻、钻进中钻具事故等作了描述,分析了这些问题的发生原因,进而提出了相应的预防措施和处理方法,从而确保钻探工作的高效进行,避免事故的发生。     

水平定向钻拖管法工程实践

结合具体工程实例,介绍了采用水平定向钻拖管法铺设过路污水管工程的施工情况,重点介绍了定向钻孔轨迹设计,详细阐述了定向钻进施工工艺,指出水平定向钻拖管法在穿越道路排水管施工中具有一定的优势,比明挖技术节约工期、降低造价。     

钻探孔内钻具事故原因分析及处理措施

根据实践经验，对遇到的钻具孔内事故进行了大量的调查研究、数据分析和资料收集，并以案例形式分析了常见的事故原因，总结经验，吸取教训，找出规律，提出处理方法，以期有效预防孔内事故的发生，提高施工效率。     

多工艺钻探技术在浅覆盖区矿产勘查中的应用研究

如何有效“剥离”覆盖层获取下伏基岩基础地质和矿产信息,是成矿带浅覆盖区地质调查工作的重要内容之一。利用钻探连续采集覆盖层—残积物—基岩等实物样品,通过分析测试确定矿体埋藏深度、品位和储量,是浅覆盖区找矿的有效方法。由于覆盖层形式多样、成分复杂以及松、散、碎的特点,常规岩心钻探遇到钻探效率低、孔内事故多、施工成本高等问题,多工艺钻探技术集成无循环钻进、空气钻进和冲洗液钻进等多种钻探方法的技术优势,根据地质要求、地层变化,通过更换取心工具、辅助器具,可提高钻探验证效率,缩短工作周期。本文梳理了国内外以空气钻进为主的多工艺钻探技术与装备的研究进展,分析不同钻进工艺的地层适用性和局限性,结合浅覆盖区矿产勘查技术方法研究与应用情况,提出多工艺钻探技术方法组合建议,为构建浅覆盖区找矿勘查技术体系提供支撑。     

浅谈筑岛钻孔桩施工

以徒骇河水中钻孔桩施工为例,介绍了筑岛围堰施工技术,分别阐述了筑岛施工便道设计方法,筑岛工艺要点及反循环钻机施工工艺流程,为同类工程施工提供了指导。     

川西平原某钻井井场钻前工程施工组织设计

根据川西平原某钻井井场工程地质条件,对井场道路、井场平整及硬化、井架基础及附属基础工程、方井等工程施工组织设计、措施和应注意事项进行了阐述,为以后类似工程施工提供了参考依据。     

Modeling impact in down-the-hole rock drilling

In this work a study of impact in Down-the-Hole (DTH) rock drilling is carried out. We present an alternative to a method previously introduced by Lundberg and his co-workers. Our model is formulated in terms of the impulse–momentum principle while Lundberg’s method is based in solving the one-dimensional wave equation. In the case of DTH drilling, the study of the subject becomes easier because the handling of many bodies interacting dynamically is simplified, and different boundary conditions, such as constant body forces, distributed forces and initial strains, can be directly included. The rock–bit interaction is modeled using both a non-linear spring and a variable gap using experimental parameter data obtained by other researchers and by a normalized quasi-static penetration test described in this work. The simulation results are in good agreement with results in previous publications as well as with experimental validation measurements carried out by the authors.     

The return of drilling fluid in large diameter horizontal directional drilling boreholes

The return of drilling fluid (drilling mud) in large diameter horizontal directional drilling (HDD) boreholes is a very important issue related to mud pressure, cuttings transport and pull back force, but this problem has not been fully solved in previous research due to the complexity and uncertainty of downhole conditions. The calculation methods of mud pressure loss in the borehole annulus are briefly introduced and the equation using a Power Law model is adopted to study the drilling mud return. A typical reaming hierarchy of a large diameter HDD project has been used to study the return direction of drilling mud and volumes of drilling mud return to the exit and entry points. The research results disclosed that the drilling mud can return to both exit and entry points at the same time, with a large majority of the drilling fluid returning to the exit point if the reamer is closer to the exit point, and vice versa. A parametric study has been conducted to find out the effect of changing parameters in the calculation equation on the drilling fluid return. The drilling mud return for those boreholes with the exit point and entry point located at different elevations has also been discussed. Finally, different types of reamers and other factors such as borehole collapse and borehole shape were taken into the consideration of drilling mud return.     

旋挖钻机成孔技术在建筑工程桩基施工中的应用

针对旋挖钻机能自动定位,垂直度自动检测,自动化程度高,钻头可快速穿过各种复杂地层的特征,提出了在杂填土、回填土较深的地质条件下用旋挖桩来代替人工挖孔桩的桩基施工技术,通过实际桩基工程施工案例显示旋挖桩比人工挖孔桩在成本、工期等方面有着很大的优势。     

旋挖钻机在卵石地层施工中的应用

结合工程实践,介绍了旋挖钻机在卵石地层施工中应用时需注意的几个技术问题,包括钻机和钻头的选择、泥浆的制备等,并提出了旋挖钻机在卵石地层中施工时的注意事项,以指导旋挖钻机施工作业。     

豫西煤系地层钻探快速成孔工艺研究

河南省是我国重要的铝土矿资源和铝工业大省,铝土矿主要分布在豫西地区,铝土矿、氧化铝和电解铝的产量在全国占举足轻重的地位,豫西地区铝土矿与煤系地层关系密切。本文通过资料收集、野外调查及研究、钻孔施工、钻探参数的采集统计对比分析和优化,探索研究豫西地区煤系地层钻探快速成孔施工工艺。以期为后续铝土矿勘查提供借鉴,达到提高找矿成果的目的。     

Assessment of glass fiber-reinforced polyester pipe powder in soil improvement

This study investigates the use of glass fiber-reinforced polyester (GRP) pipe powder (PP) for improving the bearing capacity of sandy soils. After a series of direct share tests, the optimum PP addition for improving the bearing capacity of soils was found to be 12%. Then, using the optimum PP addition, the bearing capacity of the soil was estimated through a series of loading tests on a shallow foundation model placed in a test box. The bearing capacity of sandy soil was improved by up to 30.7%. The ratio of the depth of the PP-reinforced soil to the diameter of the foundation model (H/D) of 1.25 could sufficiently strengthen sandy soil when the optimum PP ratio was used. Microstructural analyses showed that the increase in the bearing capacity can be attributed to the chopped fibers in the PP and their multiaxial distribution in the soil. Besides improving the engineering properties of soils, using PP as an additive in soils would reduce the accumulation of the industrial waste, thus providing a twofold benefit.     

旋挖钻机在之江大桥深埋硬质岩层中的应用

结合之江大桥水中钻孔灌注桩施工实例,介绍了钢护筒埋设、泥浆配制等施工技术,指出旋挖钻机在不同地层中的钻进工艺及控制要点,特别对旋挖钻机深埋硬质岩层钻进工艺进行了研究,为旋挖钻机在硬质岩层钻进提供了一种新的施工方案,对同类工程施工具有指导意义。     

潜孔锤钻进工艺在北京地铁降水工程中的应用

通过对气动潜孔锤的钻进机理进行分析,研究出适用于松散地层中大直径气动潜孔锤跟管钻进工艺,为解决目前北京地铁降水工程中出现的施工工期长、交通压力大、地面污染大等难以解决的问题提出了新技术和新方法。     

冲击钻进卵砾石地层中冲击锤问题的探讨

介绍了卵砾石地层中的冲击钻进施工过程，针对冲击锤的设计选择应用，提出了防止卡钻、埋钻事故发生的措施，解决了卵砾石地层钻进中成孔难的问题，提高了施工效率。     

几内亚某超大型铝土矿钻探项目技术经济指标分析评价

螺旋钻进是一种高效且无冲洗液循环的钻进工艺技术,国内还没有将其应用于铝土矿钻探项目的先例。经过几内亚某超大型铝土矿钻探项目的全面实际应用,为总结钻探施工经验,充分发挥和挖掘螺旋钻进工艺技术的优势,解决施工中存在的地层、钻进参数、钻头结构之间相互匹配问题,通过与其他同类矿区不同钻进工艺之间,以及该项目南、北矿区两类钻机的钻探技术经济指标的对比分析后认为,在铁帽层中钻进时,应减少刮刀钻头切削齿的数量并合理分布,减小钻头与岩层的接触面积,提高单个切削具承受的压力,并降低钻头的转速;在其他岩层中钻进时,应采用常规钻进压力,并适当提高钻头转速,从而降低孔内事故和设备故障率,提高钻进效率。     

螺杆钻具在深部矿床钻探中应用初探

文章介绍了螺杆钻具的研究和应用现状,分析了螺杆钻具在深部固体矿床钻探应用的必要性和可行性,提出了将螺杆马达组合钻具引进深部固体矿床钻探的新构想。     

旋挖钻机在核桃凹大桥中的应用

结合省道临午线临汾马务桥西—蒲县公路核桃凹大桥桩基施工实例,介绍了旋挖钻机的结构特点和施工工艺,并探讨了旋挖钻机施工质量控制措施及施工注意事项,以确保工程施工质量。