中国东西部地区震后形变有效松弛时间研究

顾及脆性转换带上的断层蠕动及其深部黏滞流对震后地表位移的影响,对5次大地震的震后垂直位移进行了最小二乘反演,并估计了有效松弛时间。反演结果表明,中国东、西部地震的有效松弛时间差异很大,其中唐山地震的有效松弛时间最长(10.3年),邢台地震次之(4.4年),而西部通海、炉霍、共和等3次地震的有效松弛时间则仅为2年多。究其原因,可能主要是由于中国东部和西部地区上地壳厚度不同以及下地壳、上地幔黏滞系数的差异所致。     

Surface wave simulation during winter with sea ice in the Bohai Sea

Sea ice can attenuate wave energy significantly when waves propagate through ice covers.In this study,a third-generation wave model called simulating wave nearshore(SWAN)was advanced to include damping of wave energy due to friction in the boundary layer below the ice.With the addition of an eddy viscosity wave-ice model,the resulting new SWAN model was applied to simulate wave height in the Bohai Sea during the freezing winter.Its performance was validated with available buoy data near the ice edge,and the new model showed an improvement in accuracy because it considered the ice effect on waves.We then performed a wave hindcast for the Bohai Sea during a freezing period in the winter of 2016 that had the severest ice conditions in recent years and found that the mean significant wave height changed by approximately 16.52%.In the Liaodong Bay,where sea ice concentration is highest,the change reached 32.57%,compared with the most recent SWAN model version.The average influence of sea ice on wave height simulation was also evaluated over a five-year(2013-2017)hindcast during January and February.We found that the wave height decrease was more significant in storm conditions even the eddy viscosity wave-ice model itself showed no advantage on damping stronger waves.     

基于伴随同化方法的Ekman模型垂向涡动黏性系数时间变化研究

为了得到一种有效的计算海水涡动黏性的途径,本文基于伴随同化方法,研究了Ekman模型中垂向涡动黏性系数(verticaleddyviscositycoefficient,VEVC)的时间变化。本文推导了时间变化VEVC的优化关系式,并利用理想实验对三个影响因素进行了探究,包括优化算法、初始猜测、观测深度,其主要结论是:(1)梯度下降法的优化效果优于共轭梯度法和有限记忆BFGS(limited-memoryBroyden–Fletcher–Goldfarb–Shanno)法;(2)初始猜测值与实际值接近时,收敛速度更快,反演误差更小;(3)反演结果对表层和次表层的流速更为敏感。本文从百慕大试验站锚泊系统(Bermuda Testbed Mooring, BTM)的数据中提取了Ekman流速,并反演了VEVC的时间变化,实际实验结果表明:(1)对于实测数据而言,仍是梯度下降法优化效果最好;(2)将VEVC设置为时间变化型的反演策略,反演效果优于常数型和深度变化型;(3)该地区VEVC在0.01m~2/s左右。该研究为Ekman流的数值模拟提供了一种确定VEVC时间变化的有效方法,对于其他动力机制的研究具有一定的参考价值。     

Study on “buoyancy-viscous force” of slurry-like soils

In newly completed hydraulic-fill dump sites, the water content of dredged slurry is usually more than two times of the liquid limit, objects can be stabilized after penetrating into dredged slurry for a certain depth. This property can be defined as the “buoyancy-viscous force” of slurry-like soils in this study. To investigate the mechanism of specific bearing capacity of slurry-like soils, the interaction between the penetrating objects and the slurry was observed. Based on the boundary layer theory of viscous fluid and the energy conservation principle, a theoretical model was established to calculate the “buoyancy-viscous force” of slurry-like soils, and then validated by load-controlled penetration tests in laboratory. It is indicated that the model prediction agreed with the experimental results very well when the water content is more than two times of the liquid limit.     

含水率变化对深部工程岩体蠕变规律的影响

针对地下工程岩体随着深度、含水状态的变化将表现出流变变形的现象,通过对深部围岩蠕变规律进行探讨,并基于工程流变力学理论和渗流力学理论,对含水率的变化对软岩蠕变变形规律及本构方程的影响进行了研究,结果表明含水率是影响岩石蠕变变形非线性程度的重要因素。     

物理模拟实验理想材料--塑化松香和有关物理参数测定

通过对塑化松香性质的介绍,结合已有的模拟实验结果,认为塑化松香是理想的模拟实验塑性材料。为了便于定量模拟,采用蠕变法和落球法测定了１４－２２℃时不同配比下的粘度,并把蠕变法测定的结果利用Ｗｅｉｂｕｌｌ曲线内推和外推到１５－２５℃内任意温下的粘度。测定结果表是,蠕变法得到的粘度值比落球法得到的粘度值更接近实际情况。通过上述两种方法测定的粘度值,基本满足定量模拟要求,可用于岩石圈多层构造变形的模拟实验     

溶液法制备钻井泥浆用的钠羧甲基淀粉(CMS)的试验研究

淀粉是一种多羟基有机高分子化合物.利用相似相溶原理,以甲醇或乙醇为溶剂,溶解淀粉,制成的钠羧甲基淀粉不溶于乙醇,有利于生成物的分离提纯;同时一氯乙酸在醇溶液中的电离度低,对反应的影响较小,有利于反应的进行.此方法具有合成工艺简单,生产效率高,成本低等特点.     

空间变化的涡粘系数对线性Munk边界层解的影响(英文)

基于Ｐｅｄｌｏｓｋｙ（１９８７）的线性Ｍｕｃｋ边界层模型,引入一随纬向空间变化的侧摩擦系数ＡＨ（ｘ）,以探讨该参数对西边界流的强化结构的影响。结果发现,在风应力和内区解保持不变的情况下,适中线性变化的ＡＨ（ｘ）会使西边界层内的向北急流和其靠内区一侧的逆流均得到加强。文中还给出摩擦应力、相对涡度及平均动能向涡动能的转化率在西边界层内的分布情况。     

Flow localization in fissure eruptions

 During a basaltic fissure eruption heat transfer from the hot magma to the surrounding rock causes a dramatic increase in the magmatic viscosity and solidification at the margins. Both viscosity contrast and solidification can amplify initial variations in the flow rate and lead to localization of the flow along the strike of the fissure. However, for typical parameters, amplification driven by solidification is slower and significantly weaker than amplification driven by viscosity variations. In fact, for the parameters examined, the amplification due to solidification is so weak that its effect is almost insignificant, whereas viscosity variation provides a strong active mechanism for flow localization. Laboratory experiments illustrate viscous localization and suggest that this mechanism is robust. The dependence of viscosity on temperature can cause a small change in the pressure of the magma chamber to lead to a large jump in the flow rate of magma through the fissure. Received: 13 March 1998 / Accepted: 27 September 1998