共查询到20条相似文献，搜索用时 125 毫秒
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目前国内高频淬火钻杆的使用寿命普遍较低,且其年消耗量又大,因而这是一个急待解决的问题。我们认为,影响目前国内钻杆使用寿命的一个最主要因素,是高频淬火淬硬层深度的合理选定。对于某一具体用途的零件来说,高频淬火时淬硬层深度的选定,通常是根据该零件的厚度或半径来决定的。本 相似文献
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镇江煤田地质机械厂金工车间 《煤田地质与勘探》1978,6(4):79-80
在全国工业学大庆会议精神的鼓午下,我们自行设计制成了高频简易淬火机床,不但能淬拉杆,换上其它夹具,还能淬齿轮、套类等另件,从而克服了以前用火焰淬拉杆,效率低、劳动强度大,淬火硬度不均匀等缺点。 相似文献
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钻杆接头表面高功率CO2激光硬化行为的研究 总被引：7，自引：0，他引：7
利用正交试验法研究了高功率ＣＯ２激光工艺参数对对钻杆接头表面硬化效果的影响，利用显微硬度计测定了硬化层硬度分布规律及组织特征，采用计算机回归处理分析得出了Ｐ，Ｄ，Ｖ，Ｅ对硬化层面积大小因子ｈ．ｂ影响的表达式，研究结果为高功率ＣＯ２激光强化钻杆接头提供了一定的依据。 相似文献
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利用正交试验法研究了高功率ＣＯ２激光工艺参数对钻杆接头表面硬化效果的影响，利用显微硬度计测定了硬化层硬度的分布规律及组织特征，采用计算机回归处理分析得出了Ｐ、Ｄ、Ｖ、Ｅ对硬化层面积大小因子ｈ·ｂ影响的表达式。研究结果为高功率ＣＯ２激光强化钻杆接头提供了一定的依据 相似文献
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一、利用500米钻机废横、立轴齿轮及300米钻机废立轴齿轮制造直径为50毫米及直径为42毫米钻杆矢锥:过去我们曾用合金钢制作矢锥,由于没有掌握材料性能,虽曾加工过30多个,分别进行了油淬与水淬,加热炉也分别采用了烘炉与电炉,但在淬火的一批矢锥中,或由于硬度不够,或因产生裂纹,没有一个取得成功,后来利用钻机废横、立轴齿轮料代替,效果很好.因钻机废横、立轴齿轮为40号铬钢,淬火性稳定,淬火后的硬度也合格,所以制出来的矢锥硬度、强度均达到技术要求,并且节约了大批合金钢.经初步鉴定,其质量并不低于外购矢锥. 相似文献
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为改善绳索取心钻杆受力工况,延长钻杆使用寿命,满足深孔及特深孔钻探施工要求,开展了对绳索取心钻杆体进行分区热处理工艺的试验研究。试验选用高钢级薄壁管材,通过对钻杆两端300 mm左右的区间内进行盐浴淬火及高温回火处理,保证了调质区域的机械性能,硬度和金相组织均匀性良好,同时热处理过渡带影响区域小。试制加工的特深孔绳索取心钻杆具有两端部螺纹连接段刚性强、杆体中部韧性好的特点。该钻杆在山东莱州西岭村矿区完成了2845.55 m深孔的钻进施工,使用情况良好。 相似文献
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This study assesses spatial and temporal sedimentological trends in four mesohaline Chesapeake Bay submersed aquatic vegetation (SAV) habitats, two with persistent SAV beds and two with ephemeral SAV beds, to determine their relationship to current and historical sediment characteristics??grain size, organic content, and accumulation rates. In general, grain size is similar among all sites, and subsurface sediment differs from surficial sediment only at one site where a thin surficial sand layer (??2?C3?cm) is present. This thin sand layer is not completely preserved in the longer-term sedimentary record even though it is critical to determining whether the sediment is suitable for SAV. Evidence for nearshore fining, similar to that observed in the deeper waters of the Bay, is present at the site where the shoreline has been hardened suggesting that locations with hardened shorelines limit exchange of coarser (sandy) material between the shore and nearshore environments. Whether the fining trend will continue to a point at which the sediment will become unsuitable for SAV in the future or whether some new type of equilibrium will be reached cannot be addressed with our data. Instead, our data suggest that SAV presence/absence is related to changes in sedimentary characteristics??persistent beds have relatively steady sediment composition, while ephemeral beds have finer sediments due to reduced sand input. Additionally, sediment accumulation rates in the persistent beds are ??9?mm/year, whereas rates in the ephemeral beds are ??3?mm/year. Thus, the ephemeral sites highlight two potential sedimentary controls on SAV distribution: the presence of a sufficiently thick surficial sand layer as previously postulated by Wicks (2005) and accumulation rates high enough to bury seeds prior to germination and/or keep up with sea-level rise. 相似文献
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P. Seethalakshmi 《Geomechanics and Geoengineering》2020,15(2):123-139
ABSTRACTMicaceous soil is believed to be detrimental for civil engineering constructions due to the effect of high compressibility, low compacted density and low shear strength. Individual mica particle has numerous intact mica flakes foliated over each other making it flexible upon loading and rebound upon unloading due to its low hardness and resilient nature. Hence, micaceous soils with mica content more than 10% are considered undesirable for highway pavements, embankments and railway track constructions. When platy mica particles are sufficiently numerous to interact with spherical sand particles, bridging and ordering phenomena are augmented within the soil mass creating unique sand-mica particle orientation (MS microstructure) unlike sand-sand particle orientation (PS microstructure). The current experimental research was conducted to evaluate the variation in stress–strain, pore pressure and effective stress path response of Sabarmati sand under the influence of mica (sand with 30% mica and pure sand) with MS and PS microstructure respectively. Effect of particle crushing on stress–strain and pore pressure response was also studied on Sabarmati sand with MS and PS microstructure. Distinctive macroscopic response was observed in Sabarmati sand with MS microstructure under the influence of mica as well as mica particle crushing. 相似文献
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In order to recycle the incineration fine bottom ash generated from municipal solid waste as a fine aggregate construction
material(<4.75 mm), a series of uniaxial compression tests were carried out according to the mixing ratio of bottom ash, the
curing temperature, the water–cement ratio, the mixing ratio of expanded poly styrene (EPS), and the curing time. As the results
of tests, the compression strengths cured 28 days of all specimens prepared with different mixing ratios are ranged between
87 and 220 kg/cm2. The water content of the hardened cement mortar is not much different with the curing time. Also, the water content is increased
with increasing the mixing ratio of bottom ash, the water–cement ratio, and the mixing ratio of EPS. The unit weight of the
hardened cement mortar is decreased with increasing the mixing ratio of bottom ash and the mixing ratio of EPS. The compression
strength of the hardened cement mortar is decreased with increasing the mixing ratio of bottom ash. The compression strength
of the hardened cement mortar cured at 30 ± 2°C and 40 ± 2°C is bigger than that of the cement mortar cured at normal temperature
(20 ± 2°C). However, the compression strength of the hardened cement mortar cured at 30 ± 2°C is bigger than that of the cement
mortar cured at 40 ± 2°C. The compression strength is increased at the range from 0.55 to 0.6 of water–cement ratio, and then
the compression strength is decreased over 0.65 of water–cement ratio. Meanwhile, the compression strength of the hardened
cement mortar is decreased with increasing the mixing ratio of EPS. 相似文献
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露水的形成及其对土壤水分的影响是进一步量化水循环和生态水文过程的重要依据。为探明露水发生规律, 在宁夏中部干旱带连续3 a观测了每30 min气象资料和表层土壤水分, 用叶片湿度传感器测算了露水量。结果表明: 该区年露水量可达56.41 mm, 75%发生在6—10月, 最大月露水量和日露水量分别为13.40 mm和0.80 mm, 主要发生在03:00—08:00;露水发生的气温、相对湿度和风速范围分别为0~24.4℃、50%~100%和0.16~1.74 m/s, 风向为30°~60°(东北风)和270°~330°(西南偏西风); 气温和露点差与相对湿度之间呈极显著线性逆相关, 气温和露点差小于3 ℃且相对湿度大于80%时极易产生露水; 日露水量为0.6 mm、0.7 mm和0.8 mm时表层5 cm土壤贮水量可分别提高0.10 mm、0.20 mm和0.25 mm。该地区年均降露量是降雨量的13.5%, 露水年均发生频率为126 d(35%), 是当地水循环和生态系统不可忽略的水源。 相似文献
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为探讨富硫化物尾矿酸化及重金属污染特征,选择安徽铜陵水木冲尾矿库浅层(0～90 cm)剖面为研究对象,对其结构特点、矿物组成、重金属(Pb、Cd、Zn、Ni、Cr、Mn、Cu和As)含量及赋存形态进行研究。结果表明,该尾矿库浅层出现分层现象,即表层为强硬化层,向下依次为弱硬化层和松散层,且呈酸性;矿物主要以辉石、长石、云母和石膏为主,由浅及深,金属硫化物及碳酸盐型矿物特征峰呈现增强的趋势;重金属呈现两种富集类型:表层(0～30cm,As、Pb)富集和中部(40～60 cm,Cd、Cu、Mn、Ni、Zn和Cr)富集型,其中Cu、Cd、As污染较为严重。由相关性分析可知,部分金属之间存在一定的伴生性,且p H值是影响重金属迁移的重要因素之一。该尾矿重金属主要以残渣态为主,其中Pb的潜在迁移能力最强,As最弱,顺序为Pb Cd Zn Ni Cr Mn Cu As。 相似文献
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Komatiites II: Experimental and Theoretical Investigations of Post-emplacement Cooling and Crystallization 总被引：1，自引：2，他引：1
TURNER J. STEWART; HUPPERT HERBERT E.; SPARKS R. STEPHEN J. 《Journal of Petrology》1986,27(2):397-437
When komatiite lavas are emplaced on the sea floor most of theheat transfer occurs through the upper lava-seawater boundary.We have investigated the cooling and crystallization of komatiitesusing a series of analogue laboratory experiments with aqueoussolutions and by theoretical analysis. In komatiites the viscosityis sufficiently low that convection occurs in the interior ofthe flow and these motions, due both to thermal and compositionalvariations, have an important influence on the characteristicfeatures of komatiites such as the strong compositional andtextural layering. The experiments have been conducted with crystallizing aqueoussolutions which display the same overall dynamical processesas solidifying komatiites. The solutions used are simple eutecticsystems having the property that crystallization from a solutionwhich is substantially more concentrated than the eutectic compositionleaves behind residual fluid which is less dense than the originalfluid. This models the decrease in density of komatiite meltson cooling, due to the crystallization of olivine. Such solutionshave been cooled strongly through the metal roof of an otherwiseinsulated container, using a typical fluid depth of 80 mm. Dendriticcrystals grew down vertically from the roof and released lightfluid, depleted in solute, which rose to form a zone of stagnantfluid at the top of the container, while the tips of the crystalsextended just below the bottom of this light layer. A layerof solid eutectic, with a horizontal front, grew more slowlyand filled in the space between the vertically oriented crystals. The growth of the crystals and the eutectic layer were monitoredvisually, and in some experiments the temperatures at the topand in the fluid were recorded, until solidification throughoutthe layer was complete. The solid block was sampled, and themelted products analysed to give vertical concentration profiles.Both the texture and composition are strongly influenced bythe fluid conditions during crystal growth. The top concentrationis that of the original solution, rapidly quenched against theroof, and the mean concentration through the region influencedby the stable fluid layer is also close to the original. Atthe bottom the concentration is high, reflecting the in situgrowth of close-packed crystals, and there is a sharp decreasein concentration at an intermediate level, between the upperand lower crystal layers. The experiments and associated theory shed new light on theconsolidation of komatiites and the development of their characteristictextures and compositions. Since the lava is convecting withinthe interior, the early stages of cooling are characterizedby a rapid decrease in temperature. Initial cooling rates of1 to 100 °C h–1 are calculated. At this stage thecrust remains thin, but as the spinifex zone develops, convectionprogressively decreases in vigour and the cooling rate decreases.Spinifex texture is considered to form by constitutional supercoolingwhich is controlled by compositional convection. As the spinifextexture develops, the olivine dendrites form a layer of depletedfluid. The tips of the crystals extend beyond this differentiatedlayer into a convecting lower region and grow preferentiallyto produce the characteristic vertically oriented spinifex texture.The composition of spinifex zones is shown to be close, butnot identical, to the initial liquid composition. The compositionalprofiles of the solid products of the experiments are similarto those found in komatiites, with the most evolved rock compositionsbeing found just above the cumulate zone. The experiments alsosuggest an alternative explanation to crystal settling for thecumulate zone, in which growth of the spinifex zone by compositionalconvection concentrates crystals suspended within the turbulentlyconvecting lower layer. 相似文献
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青藏高原多年冻土区高寒草甸土壤水分入渗变化研究 总被引：4，自引：3，他引：1
在多年冻土区典型坡面上,将坡面划分为坡下（L）、坡中（M）和坡顶（H）三个坡位,每个坡位上各选取92%、60%和30%植被盖度为研究对象,用双环入渗仪测定土壤水分入渗过程,对影响土壤入渗过程的环境因子进行了分析,并基于土壤物理特性及土壤水分的测定进行模型模拟。结果表明：研究区不同植被盖度下土壤水分入渗性能在活动层冻融过程中差异明显,初始含水量和初始入渗率具有较好的负相关关系;稳定入渗率大小为：活动层融化期,92%（0.61 mm·min-1） > 60%（0.50 mm·min-1） > 30%（0.29 mm·min-1）;活动层开始冻结期,60%（0.56 mm·min-1） > 30%（0.39 mm·min-1） > 92%（0.26 mm·min-1）。土壤水分入渗速率具有显著的坡位差异并与冻土的冻融循环过程关系紧密。主要表现为,稳定入渗速率随坡位高度的降低依次递减;同一坡位下,开始冻结期入渗速率小于融化期。在整个入渗阶段,坡顶的累积入渗量是最大的,体现了较好的入渗性能。影响高寒草甸土壤水分入渗的环境因子主要有容重,有机质含量及粒径<0.1 mm微粒。通过比较研究得出,在长江源地区,活动层融化期通用经验模型f（t）=a+bt-n更适用于该研究区域高寒草甸土壤水分入渗过程的研究,而在开始冻结期Horton模型f（t）=ic+（i0-ic）e-kt则具有更好的适用性。 相似文献
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库车坳陷K区块冲断带深层白垩系致密砂岩裂缝发育规律、控制因素与属性建模研究 总被引：1，自引：0，他引：1
针对致密砂岩气藏裂缝预测的复杂问题,本文以库车坳陷K区块为例,提出基于裂缝精细描述的属性建模方法,为该区裂缝预测提供新思路。首先基于岩心和成像测井裂缝解释模型,采用网格法获取裂缝参数,包括裂缝延伸长度(2~1850mm)、裂缝密度(平均值0.53条/米)、裂缝宽度(集中分布在0.1~0.4mm)、倾角(56°~82°)及面缝率(0.016%~0.083%)。该区影响裂缝发育的主要因素有构造、层厚以及埋深。不同构造部位裂缝发育规律不同:背斜核部发育张裂缝,其宽度和长度呈高值;翼部主要发育X剪裂缝,宽度、长度和密度都处于相对低值;近断裂附近发育高角度裂缝,密度呈高值。层厚与裂缝密度及面缝率成反比。K区目的层是深-超深埋深,随着埋深的增加,矿物脆性减弱韧性增强,超过临界点(7100m)裂缝的发育逐渐减弱。应用Petrel软件,利用裂缝精细描述数据库、构造数据和层面数据等,实现裂缝密度和面缝率模型的建立。最后,探索性的研究裂缝参数和渗透率的相关性,通过裂缝密度参数拟合渗透率模型,实现K区块的渗透率定量预测。 相似文献
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Rainfall is one of the pivotal climatic variables, which influence spatio-temporal patterns of water availability. In this study, we have attempted to understand the interannual long-term trend analysis of the daily rainfall events of ≥?2.5 mm and rainfall events of extreme threshold, over the Western Ghats and coastal region of Karnataka. High spatial resolution (0.25°?×?0.25°) daily gridded rainfall data set of Indian Meteorological Department was used for this study. Thirty-eight grid points in the study area was selected to analyze the daily precipitation for 113 years (1901–2013). Grid points were divided into two zones: low land (exposed to the sea and low elevated area/coastal region) and high land (interior from the sea and high elevated area/Western Ghats). The indices were selected from the list of climate change indices recommended by ETCCDI and are based on annual rainfall total (RR), yearly 1-day maximum rainfall, consecutive wet days (≥?2.5 mm), Simple Daily Intensity Index (SDII), annual frequency of very heavy rainfall (≥?100 mm), frequency of very heavy rainfall (≥?65–100 mm), moderate rainfall (≥?2.5–65 mm), frequency of medium rainfall (≥?40–65 mm), and frequency of low rainfall (≥?20–40 mm). Mann-Kendall test was applied to the nine rainfall indices, and Theil-Sen estimator perceived the nature and the magnitude of slope in rainfall indices. The results show contrasting trends in the extreme rainfall indices in low land and high land regions. The changes in daily rainfall events in the low land region primarily indicate statistically significant positive trends in the annual total rainfall, yearly 1-day maximum rainfall, SDII, frequency of very heavy rainfall, and heavy rainfall as well as medium rainfall events. Furthermore, the overall annual rainfall strongly correlated with all the rainfall indices in both regions, especially with indices that represent heavy rainfall events which is responsible for the total increase of rainfall. 相似文献