紧邻建（构）筑物水下爆破振动安全判据研究综述?

简要阐述了水下爆破作用下建(构)筑物安全性能评价指标,综合分析了振动幅值单因素安全判据在水下爆破紧邻建(构)筑物安全性能评定中的应用,并介绍了振速-频率双因素安全判据理论研究方法及各国安全判定标准,分析讨论了两种判据在爆破振动安全评定考虑因素与应用范围上的不足。基于累积损伤机理及振动叠加理论,介绍了爆破振动持续时间及微差爆破延时间隔对建(构)筑物安全性能的影响。提出爆破振动安全判据应从爆破振动持续时间及微差爆破延时间隔这两方面加以完善,并建议在实际工程中采用最佳微差延时间隔以达到最优降振效果。     

徐淮场路堑近邻建(构)筑物爆破安全防护技术

爆破施工时,为了保证近邻建(构)筑物的安全,结合徐盐铁路徐淮场路堑土石方爆破开挖工程,开展了近邻建(构)筑物情况下的爆破施工安全防护技术研究。在勘察分析周围环境后,对爆破有害效应采取了针对性安全防护措施:(1)爆破振动,选用岩石乳化炸药,采取延时控制爆破技术,划分爆破区域;(2)爆破飞石,覆盖炮被和沙袋,搭设防护排架,砌筑缓冲堤;(3)爆破冲击波和噪声,最小抵抗线背离建(构)筑物,装药时封闭薄弱部位,确保炮孔填塞质量,延时间隔起爆,避免大风天气施工;(4)爆破有害气体,严禁使用变质炸药,起爆后加强爆破区域的通风和洒水。在徐淮场爆破工程安全防护措施的基础上,结合已有的近邻建(构)筑物爆破安全防护经验,系统的归纳总结出近邻建(构)筑物情况下爆破施工的安全防护体系。     

徐淮场路堑近邻建(构)筑物爆破安全防护技术

爆破施工时,为了保证近邻建(构)筑物的安全,结合徐盐铁路徐淮场路堑土石方爆破开挖工程,开展了近邻建(构)筑物情况下的爆破施工安全防护技术研究。在勘察分析周围环境后,对爆破有害效应采取了针对性安全防护措施:(1)爆破振动,选用岩石乳化炸药,采取延时控制爆破技术,划分爆破区域;(2)爆破飞石,覆盖炮被和沙袋,搭设防护排架,砌筑缓冲堤;(3)爆破冲击波和噪声,最小抵抗线背离建(构)筑物,装药时封闭薄弱部位,确保炮孔填塞质量,延时间隔起爆,避免大风天气施工;(4)爆破有害气体,严禁使用变质炸药,起爆后加强爆破区域的通风和洒水。在徐淮场爆破工程安全防护措施的基础上,结合已有的近邻建(构)筑物爆破安全防护经验,系统的归纳总结出近邻建(构)筑物情况下爆破施工的安全防护体系。     

邻近建(构)筑物挖孔桩嵌岩控制爆破技术探讨

邻近建(构)筑物挖孔桩嵌岩控制爆破,涉及到建(构)筑物爆破震动破坏控制标准,以及小断面爆破夹持作用等复杂问题;根据爆炸应力传播理论和格里菲斯断裂破损度理论,反算最大一次起爆药量;爆破结果表明对邻近建(构)物的影响在可控制范围以内.     

不同水深条件下水下钻孔爆破破岩机理研究

为研究水下钻孔爆破中不同水深对爆炸冲击波和岩石破碎效应的影响,结合重庆万州长江公路大桥防撞设施水下基坑及基槽开挖工程,通过ANSYS/LS-DYNA动力有限元程序,得到不同水深条件下爆炸冲击波拉应力峰值。运用MATLAB软件对不同水深岩石破碎拉应力峰值与炮孔距离的关系进行非线性拟合,计算得到不同水深条件下不同炮孔距离的峰值拉应力理论值,进而获得不同水深条件下的爆破损伤区域。研究表明炸礁区岩石上覆30 m左右水深情况下,爆破损伤区域半径为1.5 m,对水下钻孔爆破工程实践提供了依据。     

预注混凝土爆破拆除异形筒状钢结构工艺初探

介绍了一种通过预注混凝土以实现密集钻孔大单耗爆破拆除异形筒状钢结构的新型工艺。该工艺通过向50 cm×36 cm断面的异形筒状钢结构内充填了440 cm高混凝土实现钻孔装药。再利用预先切割的引导缝来引导爆炸能撕裂钢介质以削弱甚至消除钢立柱支撑能力,进而达到促使钢结构建(构)筑物失稳倒塌的目的。采用棉被、钢丝网、防晒网制作立体防护层,用防护层包裹注砼钢柱并在防护层外侧堆码沙袋作为"贴身防护装置"使大单耗(18 kg/m~3)爆破拆除筒状钢结构安全可控。该工艺的发明与应用,使利用常规乳化炸药对异形筒状钢结构建(构)筑物进行爆破拆除的可能性得以实现。     

某石料厂石材开采爆破震动测试与分析

为了确定某石料厂石材开采时爆破震动衰减规律及其对邻近村庄建(构)筑物的安全影响大小,对该厂某次开采爆破进行了震动测试.通过分析实测数据,找到适合于该厂石材开采爆破的k、α值以及最大单响允许起爆药量,得出一系列结论,为其预测爆破地震强度和采取降震减震措施提供了理论依据.     

能量法处理行车振动与爆破振动等效性探讨

基于行车振动与爆破振动输入建(构)筑物能量的等效性,推导了行车振速换算成等效爆破振速的公式。探讨了参考爆破安全标准评价行车振动安全问题的方法。根据实测公路来往行车质点振动速度资料,将其换算成等效爆破振速,结果表明:多数工况下行车振动输入建筑物的最大输入能量密度与常规隧洞钻孔爆破相当;部分行进中的重型车辆与钻爆开挖对某些建(构)筑物结构造成的振动影响在同一量级。     

8层框架结构楼房爆破拆除后坐数值模拟

为了防止建(构)筑物拆除爆破时发生后坐现象,结合工程实例,利用ANSYS-LS-DYNA建立框架结构爆破倒塌的数值模型,其模拟结果与实际情况基本吻合,表明采用数值模拟方法预估楼房爆破后坐是可行的。以框架结构爆破后坐理论分析为指导,对影响框架结构后坐的毫秒延时时间进行数值模拟分析。结果表明,前后相邻段起爆时差一般控制250⁵00 ms为宜,且采用排分段、层同段顺序起爆产生的后坐距离相对排、层分段顺序起爆较大。因此,建议一般情况下,工程为确保倒塌反方向的建(构)筑物不被待拆结构倒塌产生的后坐所伤害,采用排、层分段的起爆方式控制后坐现象比较理想。     

8层框架结构楼房爆破拆除后坐数值模拟

为了防止建(构)筑物拆除爆破时发生后坐现象,结合工程实例,利用ANSYS-LS-DYNA建立框架结构爆破倒塌的数值模型,其模拟结果与实际情况基本吻合,表明采用数值模拟方法预估楼房爆破后坐是可行的。以框架结构爆破后坐理论分析为指导,对影响框架结构后坐的毫秒延时时间进行数值模拟分析。结果表明,前后相邻段起爆时差一般控制250~500 ms为宜,且采用排分段、层同段顺序起爆产生的后坐距离相对排、层分段顺序起爆较大。因此,建议一般情况下,工程为确保倒塌反方向的建(构)筑物不被待拆结构倒塌产生的后坐所伤害,采用排、层分段的起爆方式控制后坐现象比较理想。     

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.     

Brainstorming for ISO Strategy 2016-2020

正Responding to ISO’s appeal for survey for the to-be-developed ISO Strategy Plan for 2016-2020,SAC hosted a special workshop over the needs and comments of various fi elds on June 8 in Beijing.The workshop was attended by ISO President-elect and Ansteel General Manager Zhang Xiaogang,SAC Vice-Administrator Yu Xinli,and 30 experts from