浅析淤地坝工程设计及改进

本文根据淤地坝存在的问题,通过工程调研,在同时满足治黄(要水不要沙)和当地群众对建坝效益要求(快速淤地)的基础上,提出以"高坝大洞"的"大库容制胜"取代溢洪道的工程枢纽改进,将一次洪水总量全蓄,泥沙全拦;根据进库泥沙沉积规律和必须在24小时内将一次设计清水径流总量排完的设计原则,进行泄水洞的设计,可使淤地坝工程焕发出拦沙不减水的活力,同时降低工程投资。     

华北平原卸荷深层土体变形特性

利用压缩试验,对在华北平原地区199～479m深处所取的深层砂土、粉土、黏土土样进行取样后卸荷的变形特性进行了研究。结果表明,荷载1 200kPa和3 200kPa,199～439m土样变形量分别在0.43～1.386mm和0.725～1.896mm间;不同岩性土变形量砂土>黏土>粉土,黏土回弹最强。变形过程分析发现,砂土变形压缩初期主要为孔隙压缩,后期主要为颗粒磨损;黏土变形为颗粒相对移动和破损交互作用结果;粉土变形主要为孔隙压缩。     

Precipitation and control of BN inclusions in 42CrMo steel and their effect on machinability

The precipitation and control of boron nitrogen （BN） inclusions in 42CrMo steel were investigated and their effect on machinability was analyzed. First, the precipitation regularity of BN in 42CrMo steel was studied by theoretical calculation. Then, the machinability of the steel was investigated through contrast cutting experiments, and the composition and cooling rate of the steel were controlled to analyze the variation laws of the size, distribution, and area ratio of BN inclusions. Finally, the results were combined with the machinability of the steel to analyze the relationship among them. It is found that the machinability of the steel is mainly influenced by the diameter and quantity of BN inclusions. Fine and dispersedly distributed BN inclusions are more beneficial for the improvement in machinability of 42CrMo steel than coarse and sparse BN inclusions.     

Hot compressive deformation behavior and constitutive relationship of Al-Zn-Mg-Zr alloy with trace amounts of Sc

Abstract： The hot deformation behaviors of AI-Zn-Mg-Sc-Zr alloy were investigated in a temperature range of 340-500℃ and a strain rate range of 0.001-10 s 1 using uniaxial compression test on Gleeble-1500 thermal simulation machine. The results show that the flow stress increases with increasing strain and tends to be constant after a peak value. The flow stress increases with increasing strain rate and decreases with increasing deformation temperature. The phenomenon of dynamic recovery and dynamic recrystallization can be observed by microstructural evolutions. Based on the hyperbolic Arrhenius-type equation, the true stress-true strain data from the tests were employed to establish the constitutive equation considering the effect of the true strain on material constants （α, β, Q, n and A）, which reveals the dependence of the flow stress on strain, strain rate and deformation temperature. The predicted stress-strain curves are in good agreement with experimental results, which confirms that the developed constitutive equations are suitable to research the hot deformation behaviors of Al-Zn-Mg-Sc-Zr alloy.     

Model-based parameter identification of comprehensive friction behaviors for giant forging press

A new experimental apparatus was set up to investigate the actual fi-iction characteristics on the basis of speed control of the serve system.A modified friction model was proposed due to real time varying deformation resistance.The approach to identify the parameters of comprehensive friction behaviors based on the modified model was proposed and applied to the forging press.The impacts on parameters which the external load had were also investigated.The results show that friction force decreases with velocity in the low velocity regime whereas the friction force increases with the velocity in the high velocity regime under no external load.It is also shown that the Coulomb friction force,the maximum static friction force and the vicious friction coefficient change linearly with the external load taking the velocity at which the magnitude of the steady state friction force becomes minimum as the critical velocity.     

催化裂化柴油各馏分段碱性氮及总硫含量分布研究

对多家炼厂的催化裂化（FCC）柴油采用按体积切割馏分段的方式,对各个馏分段的碱性氮含量和总硫含量进行测试分析。结果表明,在FCC柴油中,总硫含量随着沸点的升高而升高,但碱性氮含量却随着沸点的升高而降低;以直馏柴油作对照实验,结果表明,在直馏柴油中,碱性氮和总硫含量都随沸点的升高而升高。在FCC柴油0％～60％（体积分数）的轻馏分段中集中了78．6％～86．9％的碱性氮,而在60％～100％（体积分数）的重馏分段中集中了49％～56％的硫化物。在FCC柴油中碱性氮主要集中在轻馏分,硫化物主要集中在重馏分。     

宁夏红四矿人工冻土力学特性试验研究

为了研究西部冻结岩土的物理力学性质以指导矿井建设,对宁夏红四矿副井井筒检查孔所取土样进行了人工冻结的单轴抗压强度和蠕变试验,得到了其应力——应变和蠕变规律,为西部类似矿井建设,提供了设计基础.     

下坂地水利工程沥青混凝土心墙坝工作性态分析

以新疆下坂地水利枢纽工程中沥青混凝土心墙坝的设计、施工及监测成果为例,对施工期沥青混凝土心墙变形和温度安全监测资料进行了分析,并对下游坝体内部变形的安全监测资料也进行了较详细的分析探讨.结果表明下坂地水利枢纽工程沥青混凝土心墙砂砾石堆石坝的工程质量及结构的稳定安全可靠.此结果可为相关工程提供借鉴.