反向分层爆破技术在浅竖井开挖中的应用

自上而下一次钻成贯穿整个竖井的深孔,将竖井划分为若干个爆破分段,自下而上逐层进行反向爆破,爆破产生的石渣通过自重沿竖井下部自由面落入竖井底部,爆破产生的烟尘经由钻孔到地表或上部平硐排出,爆破作业可多循环、连续作业,实现竖井快速贯通。本技术安全可靠、干扰因素少,节约了大量资金投入。     

硬岩中竖井的爆破施工

在坚硬岩石中进行竖井爆破开挖。通过对竖井地质情况和施工难点的具体分析,对原来的竖井下行全断面锥形掏槽爆破施工方法进行了科学的优化,采用先沿竖井中心打地质探孔为竖井爆破施工创造第2个自由面,提高了炮孔利用率,解决了通风排烟排水对爆破作业的干扰。同时重新对爆破参数设计、施工配套机械设备选择、工序衔接及装碴运输等制约开挖施工的关键环节进行了优化,为竖井的顺利、安全施工创造了条件,取得了较好的爆破效果和经济效益。     

中深孔爆破技术在小断面超深竖井中的应用

中深孔爆破施工方法是竖井快速施工的有效途径,结合大红山铁矿1279 m小断面箕斗竖井中深孔爆破技术的应用情况,对钻装机具、掏槽形式、爆破参数、起爆方式等关键技术措施进行分析。SJZ-5.6型伞钻对于井筒净直径5~6 m的情况是适宜的;二阶直斜眼掏槽方式能提高爆破效率;导爆管雷管及电磁雷管爆破网路可提高准爆率。中深孔爆破技术有力保障了该超深竖井的优质快速施工,连续六个月进尺均超过100 m,该箕斗竖井的爆破经验可为同等围岩条件下的小断面超深井筒掘进爆破施工提供理论与技术支持。     

超大断面竖井深孔爆破成井技术

为实现超大断面竖井高效掘进,提出基于多孔球状药包爆破和预裂爆破的深孔爆破成井技术。首先根据竖井掘进深度大、断面大的特点,设计了导井爆破、基于预裂爆破的侧崩爆破和破顶爆破的分区爆破方案;同时根据多孔球状药包爆破漏斗理论和延时爆破降振机理,提出导井精确短延时爆破成井技术,通过理论计算确定了导井爆破同层短延时时间和层间延时时间等爆破参数;基于预裂爆破作用机理,确定了周边孔预裂爆破参数。最后将研究结果在引松供水工程超大断面竖井掘进中进行现场试验,成功爆破形成了直径20m、高度50 m的调压井。试验结果证明了深孔爆破成井技术应用于超大断面竖井掘进的可行性,研究结果具有广泛的推广应用前景。     

孤石深孔爆破对临近竖井的振动影响研究

采用现场测试和数值分析相结合的方法,研究了孤石深孔爆破对临近竖井结构振动影响.结果表明:减振孔可以有效减缓孤石爆破对竖井基坑围护桩的破坏;隔离孔可以保证相临爆区孤石的完整性;增加孤石爆破分区,减小炮孔间距,减少一次爆破量,可以有效控制竖井爆破振速.以孤石分区5区为例,将炮孔间距调整为0.5 m×0.4 m,炸药直径调整...     

水压爆破法部分拆除钢筋混凝土竖井

一、工程概况石家庄市四十中人防工程四号竖井,上口边长为2.5m的正方形,竖井深度为7m,壁厚为0.3m,它是整体浇注的钢筋混凝土结构(混凝土标号250号)。因改建工程需要,需拆除该竖井上部1.5m,下部西面拆除,其余三面保留,因井壁很薄且布筋又密,难于用常规的钻眼爆破法拆除,故采用水压爆破法。但是,由于该竖井部分拆除,水压法也有一定的难度。四号井全部在地下,井口与地面平齐,     

节理裂隙围岩小直径深竖井爆破开挖

节理裂隙发育围岩地区小直径、深竖井的爆破开挖,很容易造成塌方和超挖,所以其设计与施工一直是关注重点。结合长沙市森林防火监测站项目80 m深的小直径竖井工程,针对小断面、深竖井的工程特点以及表层围岩石风化严重的地质条件,采取小断面反井爆破、分次扩挖,及地表层正向爆破等施工技术,对保证竖井开挖质量及安全措施进行了详细的分析。结果表明工程设计与施工工艺切实可行。     

地铁竖井矿山法施工减震设计及效果分析

以大连地铁202标段促春区间竖井施工为例,进行了以竖井周边距离最近建筑为爆破安全控制距离,地层特性与场地条件相结合的分段爆破设计,提出了控制爆破技术与"短进尺、弱爆破"减振措施。在竖井爆破施工期间进行了竖井爆破震动监测工作。通过不同水平爆破监测,得到围岩介质振动速度处于0.28~1.85 cm/s,质点振动频率在16.97~42.24 Hz之间。监测结果表明基于最近安全距离的减震设计及减震技术措施能够满足工程实践和规范的要求,为城市地铁建设减震优化设计提供了科学依据和技术支撑。     

深井掘进一次成孔分段爆破试验研究

根据对深 40 m竖井的一次成孔分段爆破现场试验研究,采用有效的成孔、堵塞、装药、起爆工艺和技术,给出了合理的爆破参数.     

闸门室洞挖爆破施工技术

以锦屏二级水电站特大断面隧洞工程建设为背景,运用隧道工程理论和施工方法,论述了闸门室分层爆破、岩锚梁高精度爆破和竖井二次爆破等各种爆破施工技术,达到了预期开挖爆破效果.同时提出了变形观测等辅助手段和加固措施,保证了复杂地质条件下洞挖爆破施工的安全.     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...     

Effect of Oxide Assisted Metal Nanoparticles on Microstructure and Morphology of Gallium oxide Nanowires

Several researches have been reported about the characteristic of β-Ga2O3 nanowires which was synthesized on nickel oxide particle. But indeed, recent researches about synthesis of β-Ga2O3 nanowires on oxide-assisted transition metal are limited to nickel or cobalt oxide catalyst. In this work, Gallium oxide (β-Ga2O3 ) nanowires were synthesized by a simple thermal evaporation method from gallium powder in the range of 700 - 1000℃ using the iron, nickel, copper, cobalt and zinc oxide as a catalyst, respectively. The β-Ga2O3 nanowires with single crystalline without defects were successfully synthesized at the reaction temperature of 850, 900 and 950℃ in all the catalysts. But optimum experimental condition in synthesis of nanowires varied with the kind of catalyst. As increasing synthesis temperature,the morphology of gallium oxide nanowires changed from nanowires to nanorods, and its diameter increased. From these results, we could be proposed that the growth mechanism of β-Ga2O3 nanowires was changed with synthesis temperature of nanowires. Microstructure and morphology of Synthesized nanowire was characterized by HR-TEM, FE-SEM, EDX and XRD.     

The Influence of Nitrogen and Boron Implant into Silicon Substrate on the Phase and Internal Stress of c-BN Films

Cubic boron nitride(c-BN) film was deposited on a Si (100) substrate by the RF-magnetron sputtering.The mainly problems for fabrication of c-BN films are the low purity and high intrinsic compressive stress. In order to solve the two problems, the c-BN film with the buffer interlayer was deposited on the substrate which had been implanted with nitrogen and/or boron ions. The results show: the implantation of nitrogen ions can obviously increase c-BN content and reduce the internal stress slightly; while the implantation of boron shows no obvious improvement to the content of c-BN, which can reduce the internal stress in the film obviously. In addition, it is suggested that the implantation of nitrogen and boron shows the best result, which not only can increase the content of c-BN, but also reduce the internal stress in the c-BN film obviously.