深覆盖非均质复杂结构围堰拆除爆破设计

官地水电站尾水出口围堰具有深覆盖、非均质、卸荷基岩、堰体结构复杂的特点,围堰距离出口闸门及启闭机距离≤30m,闸室与围堰间明渠底板为1:4倒坡,明渠结构混凝土与围堰相接,与对岸拌合楼距离≤90m,爆破拆除规模大、要求高。介绍了该围堰爆破的方案选择、参数及起爆网路设计,爆破安全防护和施工技术措施,可供类似工程参考。     

大朝山单跨拱桥爆破震动速度反应谱特征

根据大朝山水电站 3#、4# 尾水出口砼围堰及岩埂拆除爆破振动速度监测成果,采用单自由度体系结构动力响应分析方法,建立了澜沧江大桥(单跨拱桥)的爆破震动速度反应谱.     

三峡三期上游碾压混凝土围堰拆除方案综述

介绍了三峡三期上游碾压混凝土围堰的结构特性、拆除要求、拆除方案研究等内容,分析了拆除技术难点,并重点介绍了选定方案“围堰中段预埋药室爆破 两端深孔爆破“的总体设计思路和拆除实施效果.     

锦屏二级水电站导流隧洞进口围堰拆除爆破

介绍了锦屏二级水电站导流隧洞进口围堰拆除工程的岩坎拆除爆破方案、爆破参数、爆破网路以及爆破安全防护措施.水下岩坎拆除的高度为10 m.考虑满足水力冲渣、保证邻近混凝土结构的爆破振动安全等因素,岩坎拆除爆破采用平均1.8 kg/m3的高单耗设计,采用孔排间微差起爆网路,孔内采用高段位非电毫秒导爆管雷管起爆,孔外采用低段位...     

白鹤滩水电站尾水出口围堰拆除爆破设计与施工

白鹤滩水电站尾水出口围堰拆除爆破具有工期紧、任务重、岩石条件复杂、近距离靠近保护物、水流冲渣要求高等突出特点。针对施工中的重难点,采取“分期分区分层”爆破拆除方案,将单个围堰分为“两期三层八区”,通过预留经济围堰,提前拆除水上部分等措施,克服了工程量大、工期紧的难题;采用“大直径钻机造孔、孔内套管护孔”的方式,有效减少了复杂地质条件下塌孔的产生,提高了施工工效也确保了爆破效果;“高单耗、低单响”的药量设计、“孔间分段、孔内延时”的爆破网路设计,即能满足近距离爆破条件下质点振速安全控制要求,又确保了爆后渣料块度满足水流冲渣条件。工程应用结果表明,最不利工况下爆破诱发质点峰值振速为11.85 cm/s,小于结构混凝土允许的安全控制标准12 cm/s;实测水击波峰值压力为0.12 MPa,小于水工钢闸门的安全允许控制值0.4 MPa;爆后绝大部分渣料块度粒径控制在40 cm以内,大块率控制在5%以内,爆破效果良好,满足水流冲渣条件。     

三峡工程三期碾压混凝土围堰爆破拆除方案

该项工作是国家“八五”科技攻关课题“85 - 1 6 - 0 3”《三峡工程枢纽建设关键技术研究》的分子题。文章针对三峡工程三期碾压混凝土高围堰在工程完建后进行水下爆破拆除的关键技术问题 ,提出了快速爆破拆除、切割后倾覆拆除、粉碎性爆破拆除等数种可行性方案 ,分析了各种爆破方案的施工条件及优缺点 ,探讨纵向围堰拆除方案及围堰修建时应采取的工程措施 ,讨论了各爆破方案的爆破安全问题     

碾压混凝土围堰爆破拆除震动安全分析

在高坝洲水电站下游纵向碾压混凝土围堰爆破拆除中进行了爆破测震试验。对现场实测爆破震动波形的研究表明 ,采用使堰体翻转的爆破拆除方案时 ,选用条形间断装药、雷管分段延时起爆、隔震孔、预裂缝等技术措施 ,完全能够降低大爆破带来的结构振动 ,确保相邻堰体的安全     

碾压混凝土围堰爆破拆除震动安全分析

在高坝洲水电站下游纵向碾压混凝土围堰爆破拆除中进行了爆破测震试验。对现场实测爆破震动波形的研究表明 ,采用使堰体翻转的爆破拆除方案时 ,选用条形间断装药、雷管分段延时起爆、隔震孔、预裂缝等技术措施 ,完全能够降低大爆破带来的结构振动 ,确保相邻堰体的安全     

岩滩碾压混凝土围堰拆除关键部位的处理

岩滩电站上下游碾压混凝土(Rcc)围堰拆除,采用非电塑料导爆管接力式起爆网路,顺序微差控制爆破,成功地拆除 Rcc 总量10.08万m~3。爆破后邻近建筑物安然无恙。现介绍围堰拆除几个关键部位实施安全爆破的主要技术。     

某引水工程取水口围堰和预留岩坎拆除爆破

某引水工程取水口前端预留岩坎与已建水库相连,距离取水口塔体和已建大坝较近,为确保周边建筑物安全,拆除时先进行预留岩坎迎水坡爆破剥离,减少其厚度,再对混凝土围堰和剩余预留岩坎进行分层分区拆除爆破。爆破施工中采取了有效的安全爆破控制技术措施,降低了施工难度,保证了施工质量,达到了预期的效果。通过分层分区拆除爆破,有效解决了围堰和预留岩坎在大型水库水下淹没深度较深且不需人为降低水库水位进行拆除爆破的难题,为今后类似工程积累了宝贵的经验。     

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 ...     

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     

CNAS Passes APLAC's PTP Review

正The review group of Asia Pacific Laboratory Accreditation Cooperation(APLAC)carried out a 4-day peer review of the proficiency testing provider(PTP)for China National Accreditation Service for Conformity Assessment(CNAS)from July 28 to 31,2014.CNAS passed the PTP review with excellent performance.Two senior peer reviewers of APLAC made a comprehensive,rigorous and detailed review of CNAS’s PTP accreditation activities,and made the on-spot inspection of the review groups in Shanghai and Shenzhen respectively.