Influence of seismic input on response of Baihetan arch dam

The dynamic responses of the arch dam including dam-foundation-storage capacity of water system, using two different earthquake input models, i.e. viscous-spring artificial boundary （AB） condition and massless foundation （MF）, were studied and analyzed for the 269 m high Baihetan arch dam under construction in China. By using different input models, the stress and opening of contraction joints （OCJs） of arch dam under strong shock were taken into consideration. The results show that the earthquake input models have slight influence on the responses including earthquake stresses and openings of contraction joints in different extents.     

外掺材料对多孔水泥混凝土胶浆强度的影响研究

文章采用超细粉煤灰与硅灰的复合技术配制多孔水泥混凝土水泥浆体试件.通过与双掺硅灰和减水剂、双掺粉煤灰和减水剂以及复合掺粉煤灰、硅灰和减水剂的情况对比,系统研究了硅灰粉煤灰作为外掺挤对多孔水泥混凝土水泥浆体的强度的影响.实验结果表明,由于硅灰与超细粉煤灰的复合,在水泥浆体形成过程中,这2种材料充分发挥了各自的功能效应,使得多孔水泥混凝土水泥浆体的强度性能显著提高.文章通过扫描电镜试验,剖析了超细粉煤灰与硅灰复合效应的机理,论证了用超细粉煤灰和硅灰以及减水剂复合配制多孔水泥混凝土水泥浆体的可行性.     

波浪对双层圆弧型贯底式开孔介质防波堤的绕射

为研究波浪对双层圆弧型贯底式开孔介质防波堤的绕射问题,利用比例边界有限元方法(SBFEM)建立该问题的半解析解模型.分析时将双层圆弧延伸构建出2个虚拟同心圆可将整个流场可划分成2个有限域和1个无限域.利用变分原理推导出了关于势函数的各个子域SBFEM方程,并对SBFEM方程进行了求解.数值算例验证了该方法是一种只需离散最外边界而且用很少单元便能得到精确结果的高效算法.给出了短峰波波向、相对波数、内外半径比、圆弧段的位置、张角以及孔隙影响系数等因素对整个结构波浪绕射的影响.结果表明,双层圆弧型贯底式开孔介质防波堤与以上参数的变化密切相关.     

基于小波消噪的改进的非参数解集模型

首先对文献[2]提出的非参数解集模型进行了改进，然后建议了用小波技术对水文序列进行消噪处理再估计非参数解集模型中的带宽系数的策略。改进的非参数解集模型无需对水文序列相依结构（线性或非线性）和概率分布形式（正态分布、P-Ⅲ型分布）作假定，且能保持水文序列的各种统计特性，适用于时间量和空间量的随机解集。最后以金沙江流域某站月径流随机模拟为例进行验证，研究表明：改进模型能反映实测月径流系列的变化特性，因而用于水文随机模拟是可行的。     

水平管气液两相变质量流流型从分层流向非分层流的转变

基于文献中提出的针对常规管中气液两相流分层流稳定性的分析,考虑管壁入流对流型的影响,通过公式推导和分析得出了水平管中气液两相变质量流流型从分层流向非分层流转变的准则。通过室内实验研究和预测计算,分析了3种不同的流型转变准则中多个入流流量下管壁入流对流型转变的影响。研究结果表明,实际水平井筒的单位入流流量通常较小,对本地管道单元流型预测的影响可以忽略不计,但是通过不断累积,使得下游管道中流动参数发生变化,从而影响了下游管道单元中气液流动的流型。因此水平孔缝管中气液两相变质量流的流型判别可以采用常规管流型判别准则,但要分段进行。     

Microstructure evolution of CMAS glass below melting temperature and its potential influence on thermal barrier coatings

CaO–MgO–Al₂O₃–SiO₂ (CMAS) deposition significantly degrades the performance of thermal barrier coatings (TBCs). In this study, the microstructure evolution of CMAS glass at temperatures below its melting point was investigated in order to study the potential influence of temperature on the applicability of CMAS glass in TBCs. The CMAS glass fabricated in this study had a melting point of 1240 °C, became opaque, and underwent self-crystallization when the temperature reached 1000 °C. After heat treatment at 1050 °C, diopside and anorthite phases precipitated from the glass; at a higher temperature (1150 °C), diopside, anorthite, and wollastonite were formed as the self-crystallization products. An increase in the dwelling time resulted in the transformation of diopside to wollastonite and anorthite. At 1250 °C, all products formed a eutectic microstructure and melted. The results indicate that even at low temperatures, CMAS glass underwent microstructure evolution, which could influence the coating surface and stress distribution when deposited on TBCs.     

An improved form of smoothed particle hydrodynamics method for crack propagation simulation applied in rock mechanics

The simulation of crack propagation processes in rock engineering has been not only a research hot spot among scholars but also a challenge. Based on this background, a new numerical method named improved kernel of smoothed particle hydrodynamics(IKSPH) has been put forward. By improving the kernel function in the traditional smoothed particle hydrodynamics(SPH) method, the brittle fracture characteristics of the base particles are realized. The particle domain searching method(PDSM) has also been put forward to generate the arbitrary complex fissure networks. Three numerical examples are analyzed to validate the efficiency of IKSPH and PDSM, which can correctly reveal the morphology of wing crack and the laws of crack coalescence compared with previous experimental and numerical studies.Finally, a rock slope model with complex joints is numerically simulated and the progressive failure processes are exhibited, which indicates that the IKSPH method can be well applied to rock mechanics engineering. The research results showed that IKSPH method reduces the programming difficulties and avoids the traditional grid distortion, which can provide some references for the application of IKSPH to rock mechanics engineering and the understanding of rock fracture mechanisms.     

纤维对水泥土加固效果影响的试验研究

将短切玄武岩纤维和水泥掺入取自长春地区的黄土中,进行无侧限抗压强度试验.主要研究纤维掺量、纤维长度对纤维水泥土无侧限抗压强度特性的影响.试验结果表明:同一纤维质量掺入比下,随着纤维长度的增加,纤维水泥土抗压强度大体呈上凸型曲线形式,曲线最终趋于无纤维掺入的水泥土强度,说明纤维分布均匀性和纤维分布密度对强度影响较大;同一...     

城镇污水处理厂硫自养反硝化深度脱氮研究

为了探究硫自养反硝化滤池用于城镇污水处理厂中水的深度脱氮效能,通过中试实验模拟实际生产情况,以邯郸市东污水处理厂为研究对象,分析中试运行问题并核算运行成本。结果表明：中试系统处理规模为200 m³/d,直接运行成本为0.13元/m³;硝酸盐氮的去除率在98%以上,去除效果显著;能在不影响其他出水指标的情况下有效地降低出水总氮。     

基于SFM方法的不同倾角桥墩绕流局部冲刷特性试验

桥墩绕流冲刷是水流、泥沙和桥墩三者相互作用的结果,桥墩周围复杂的水沙运动关系是造成桥梁水毁的重要原因。定量分析桥墩冲刷地形特征规律及其与水流之间的相互作用关系,是深入研究桥墩绕流水沙作用机理及实际工程应用的重要突破口。本文开展两种坡降条件下不同倾角均匀沙动床桥墩绕流冲刷试验,并沿下游方向设置四个模型倾角0°、5°、10°、15°。使用粒子图像测速系统（Particle Image Velocimetry,PIV）测量桥墩绕流二维流场,并基于运动摄像恢复结构技术（Structure From Motion,SFM）实现冲刷地形三维重构,在此基础上分析床面冲刷三维地形结构和绕流流场特征,以构建紊流结构与冲刷地形相互耦合作用关系。结果表明：（1）SFM方法可实现冲刷地形三维结构重构,冲刷试验平衡时,模型前方和两侧冲刷坑较深,后方冲刷坑出现凸起,沿水流方向倾斜顺延上升至床面。（2）冲刷坑尺寸、面积和体积均随水流强度增大而增大,随倾角增大而减小。不同截面处冲刷坑面积、体积随坑深呈开口向上抛物线趋势增大。（3）桥墩模型对后方流向流速扰动范围随倾角增大而减小,对展向流速影响范围随倾角增大而增大。（4）随模型倾角增加,旋转强度与剪切应力影响范围均减小。剪切应力下切较易形成桥墩周围较深冲刷坑,而位于桥墩两侧大尺度流向涡向下游延伸,将促使桥墩后侧方浅长凹槽形成。