近海竖井冻结天窗成因与治理措施

瑞海矿业公司主竖井距海边仅35 m,属于富水软弱地层,表土段采用冻结法施工.受潮汐及周边海水养殖场抽取地下水影响,导致冻结壁容易形成"天窗".采用冻结器纵向测温技术预测冻结壁开窗部位,采取补打加强冻结孔的措施,加快了冻结壁交圈,效果较好,值得推广.     

徐楼铁矿主、副井冻结末端注浆法施工实践

徐楼铁矿主、副井地处淮北平原，井筒断面小，穿过第四系流沙层。因冻结深度设计不够，造成竖井进入隔水的基岩前被迫在准冻结状态下采用注浆法施工，文章对其分析总结并提出对策。     

采用椭圆断面进行竖井延伸

针对国内首例椭圆竖井施工实践，进行了竖井断面选取的经济对比分析，详述了竖井施工流程，对类似竖井施工具有重要参考价值。     

采用椭圆断面施工竖井

针对国内首例椭圆竖井施工实践，进行了竖井断面选取的经济技术对比分析，详述了竖井施工流程，对类似竖井延伸施工具有重要参考价值。     

无井架竖井施工技术及应用实例

介绍了一种新型无井架竖井施工工艺技术:在施工条件允许时,可与地面钢筋混凝土井塔和地下竖井同时施工,与通常竖井施工方法相比,可缩短施工工期,节约建设投资。通过无井架竖井施工案例及分析总结了其技术特点,详细的无井架竖井施工应用实例,可为该技术的推广应用提供借鉴经验。     

竖井施工坠罐事故分析与预防

通过典型竖井施工坠罐事故案例,分析了竖井施工过程中坠罐事故产生的原因,应用事故树方法对竖井掘进坠罐事故进行了定性分析,提出了控制坠罐事故基本事件发生的途径,为竖井施工安全管理提供科学依据。     

矿山竖井施工的管理研究

竖井是矿山开拓的重要工程,也是地下矿山开拓系统施工管理的难点。竖井的施工安全管理非常重要,从竖井施工组织设计开始,施工人员应严格依据设计的要求,在确保技术、质量的前提下,同时满足安全管理的要求。并且必须考虑矿山实际地质情况,采用先进、合理的施工技术,以利于确保竖井施工的质量、安全和经济,从而使得竖井施工顺利进行,确保矿山建设的按时、高效开展,为矿山早日投产提供保障。     

竖井施工主要技术参数的确定研讨

竖井施工中,基岩段技术参数的确定是核心,是竖井施工质量、施工进度、施工安全和工程造价的决定性因素。     

钢管竖井架在高层建筑施工中的应用

随着建筑业改革的不断发展,竖井架在高层建筑中的作用不容忽视。本文简要介绍了用钢管扣件搭设竖井架的经验,提出了钢管扣件竖井架在高层建筑中解决垂直运输问题的施工方法,并通过施工实例证明了钢管竖井架的可靠性与适用性。     

某金矿竖井改造实践

从竖井改造的必要性、改造论证、施工准备、施工组织管理等环节,介绍某金矿竖井改造的全过程,阐述如何提高竖井改造的施工进度,为类似工程的改造提供参考。     

A comparative assessment of cryosurgical devices: application to prostatic disease

OBJECTIVES: To determine the comparative freezing ability of the Cryotech (CT) and AccuProbe (CMS) cryosurgical systems. METHODS: Four conditions designed to model clinical situations were produced: (1) Single-probe performance in water at 17 degrees C; (2) five-probe performance in water at 17 degrees C; (3) single-probe performance in gel at 22 degrees C; and (4) single-probe performance in bovine liver. Parameters evaluated included temperatures at various time points (rates to and final low temperature), configuration of a freeze zone, and shaft freezing characteristics. In addition, isotherms were measured at predetermined distances from the center of the freeze zone. RESULTS: Both systems provided freezing of various media under operational conditions. In water, the CMS 3-mm probe delivered more rapid freezing temperature rates than the 3-mm CT probe, with a 110 degrees C difference in probe surface temperature. In gel, the CMS probe increased freeze volume fourfold versus a twofold increase for the CT probe. In bovine liver, there was nearly equivalent performance with respect to geometry of the freeze ball. Extrapolation of the CT cooling curve indicated temperature equivalence at 30 minutes. A larger shaft diameter 4.9-mm CT probe produced results similar to the CMS probe in all the tested media. In addition, the freeze configuration of the CMS probe was spherical; the CT configuration was more cylindrical. CMS probe (equivalent diameter) tip temperatures were on average 100 degrees C lower. CONCLUSIONS: Our tests demonstrated differences between the CMS and CT probe. The major differences are in the configuration of the freeze zone and shaft freezing. In equivalent conditions, the CMS 3-mm probe delivered more rapid cooling rates, a more spherical freeze ball, and lower absolute temperatures than the CT 3-mm probe. The larger CT probe produces equivalent freezing temperatures to the CMS probe, albeit with a more spherical shape. However, these in vitro systems may not adequately reflect varied prostate morphology. Further research is under way to determine if these differences affect relative efficacy of cryotherapy of the prostate.     

模拟冻结法施工环境对大体积混凝土的性能影响

模拟大体积混凝土在冻结法施工环境的状态,将混凝土浇筑7 h后施加?5/60 ℃和?5/70 ℃温差,测试施加模拟环境后混凝土的超声波参数、抗压强度、劈裂抗拉强度、氯离子扩散系数和冲击倾向性,分析混凝土的扫描电镜微观形貌。结果表明,冻结施工环境对于混凝土内部会造成一定的损伤,且平行于加温方向的损伤要大于垂直方向,C50混凝土的损伤大于C70混凝土,温度梯度会加剧混凝土内部的损伤。模拟冻结环境会对混凝土抗压强度、劈裂抗拉强度、氯离子渗透性能和冲击倾向性造成不利影响,温差与性能降低率正相关,且这种影响对于低强度混凝土更加显著。模拟冻结环境造成混凝土试块的内部微观结构不均匀,低温端混凝土结构比较疏松,高温端结构比较致密,导致部分混凝土性能的降低。      

早龄期冻结土压力与负温耦合作用的井壁混凝土性能

研究了早龄期冻结压力等荷载、负温及早龄期荷载和负温耦合作用对冻结竖井井壁C60混凝土抗压强度、氯离子扩散系数和声发射特征的影响,并通过扫描电镜分析其内部微裂缝.结果表明:早龄期荷载加载时间越早对混凝土28d抗压强度的影响越大,当外部荷载作用时间在3d以后且荷载水平在混凝土当天强度40%以内时,混凝土28d强度几乎不受影响;冻结井井帮负温环境会延缓井壁混凝土早期水化,防冻剂的加入利于加快混凝土水化和强度的发展;在早龄期荷载及负温耦合作用下,混凝土28d抗压强度降低明显,氯离子扩散系数大大增加,混凝土的渗透性由"中"变为"高",内部产生了缺陷和微裂缝导致声发射"活跃阶段"提前,且混凝土呈现明显的塑性变形.      

河东金矿多级机站通风系统的应用

河东金矿大矿井通风时，根据矿山的具体现状，用多级机站通风系统代替了原来的单翼对角工通风系统，达到了改善作业环境粉尘合格率的目的，并解决了竖井冬季结冰问题。     

The Impact of Soil Freezing/Thawing Processes on Water and Energy Balances

A frozen soil parameterization coupling of thermal and hydrological processes is used to investigate how frozen soil processes affect water and energy balances in seasonal frozen soil. Simulation results of soil liquid water content and temperature using soil model with and without the inclusion of freezing and thawing processes are evaluated against observations at the Rosemount field station. By comparing the simulated water and heat fluxes of the two cases, the role of phase change processes in the water and energy balances is analyzed. Soil freezing induces upward water flow towards the freezing front and increases soil water content in the upper soil layer. In particular. soil ice obviously prevents and delays the infiltration during rain at Rosemount. In addition, soil freezing/thawing processes alter the partitioning of surface energy fluxes and lead the soil to release more sensible heat into the atmosphere during freezing periods.     

数值模拟在反应塔冷却系统设计中的应用

通过对闪速炉反应塔冷却系统的冷却单元建立三维模型,并利用计算流体动力学软件FLUENT进行了数值模拟研究得出:冷却单元的冷却效果良好,产生的低温区域容易促进反应塔内壁挂渣的形成;冷却系统主要的散热损失由冷却水带走,且冷却单元的冷却强度与冷却水的进水温度及进水量关系不大;冷却系统的总循环水量及温升可以通过分别计算各不同冷却单元的冷却水量和温升得到等结论。     

南李庄矿主井施工突水防治技术

防治水是矿山建设施工的重要环节。南李庄矿属于水文地质条件复杂的大水岩溶矿山,介绍了主井掘进-129m水平突水及治水过程,在查清该矿区水文地质条件及矿井突水要因的基础上,为综合防治竖井掘进期间通过特殊地质构造段突水,提出相应的主井掘进帷幕注浆防治水技术及措施,并在掘进工程中收到了良好的应用效果,对类似特殊条件下的矿山井巷掘进工程具有借鉴意义。     

Cryopreservation of unfertilized mouse oocytes: the effect of replacing sodium with choline in the freezing medium

Although embryo cryopreservation has become commonplace in many species, effective methods are not available for routine freezing of unfertilized eggs. Cryopreservation-induced damage may be caused by the high concentration of sodium ions in conventional freezing media. This study investigates the effect of a newly developed low-sodium choline-based medium (CJ2) on the ability of unfertilized, metaphase II mouse eggs to survive cryopreservation and develop to the blastocyst stage in vitro. Specifically, the effects of cooling to subzero temperatures, thawing rate, LN2 plunge temperature, and equilibration with a low-sodium medium prior to freezing are examined. In contrast to cooling to 23, 0, or -7.0 degreesC in a sodium-based freezing medium (ETFM), cooling in CJ2 had no significant negative effect on oocyte survival or development. Oocytes frozen in CJ2 survived plunging into LN2 from -10, -20, or -33 degreesC at significantly higher rates than oocytes frozen in ETFM. With the protocol used (1.5 M PrOH, 0.1 M sucrose, -0.3 C/min, plunging at -33 degreesC) rapid thawing by direct submersion in 30 degreesC water was more detrimental to oocyte survival than holding in air for 30 or 120 s prior to transfer to water. Equilibration of unfertilized oocytes with a low-sodium medium prior to cryopreservation in CJ2 significantly increased survival and blastocyst development. These results demonstrate that the high concentration of sodium in conventional freezing media is detrimental to oocyte cryopreservation and show that choline is a promising replacement. Reducing the sodium content of the freezing medium to a very low level or eliminating sodium altogether may allow oocytes and other cells to be frozen more effectively.     

攀成钢10 m2竖炉球团喷加转炉污泥的工业试验

本文介绍了攀成钢用转炉污泥浆代替竖炉造球添加水的工业试验。在10m^2竖炉球团造球盘喷加转炉污泥浆后显著改善了生球质量和成品球质量，降低了膨润土消耗，试验结果表明：用转炉污泥浆取代造球添加水，能改善和提高生球和成品球某些质量指标。在润磨工艺条件下，膨润土配比可降低30％-50％，效益十分显著。