竖向入射S波作用下单桩水平地震响应简化解析方法

基于连续介质模型并考虑桩-土运动相互作用,将单桩视为一维线弹性梁,研究了竖向入射S波作用下的单桩水平地震响应问题。将竖向入射S波模拟为基岩水平位移,基于平面应变模型建立的土体控制方程,推导出地震作用下土体水平动力阻抗函数表达式。将土体阻抗代入单桩控制方程并联立桩-土接触条件及桩顶和桩底的边界条件,得出了竖向入射S波作用下单桩的地震响应解析解。通过将所得解与已有文献理论解和有限元结果进行对比,验证了该方法的合理性。基于所得理论解进行参数分析得出：桩-土模量比的增加可以明显降低桩-土运动相互作用因子的最小值,而较大桩身长径比以及土体滞回阻尼对桩-土运动相互作用因子的影响较小;对于桩顶水平地震放大因子来说,桩-土模量比的增加仅在高共振频率处抑制其幅值,较大桩身长径比对其影响较小,而滞回阻尼比的增加会显著抑制共振频率处的幅值;桩身地震响应仅在较小桩径比时受桩-土模量比的影响明显,并随桩-土模量比的增加而降低。     

承压含水层井流-盖层弯曲效应的解析理论

指出承压含水层盖层的弯曲变形与开采井周围的径向地下水运动存在相互作用, 而这一效应在传统的井流理论中没有被认识到.通过引入弹性薄板理论, 建立了无越流的承压含水层井流-顶板弯曲效应的解析模型, 同时考虑了含水层和水的压缩性, 结果表明Theis井流方程给出的抽水降深偏小.在此基础上推导了有越流承压含水层井流-盖层弯曲效应的偏微分方程, 求出了解析解, 并与传统理论的结果进行了对比, 表明Hantush-Jacob公式计算的降深也是偏小的.在抽水井附近和抽水初期, 传统理论可能导致显著的相对误差.      

岩石爆破过程S波的产生机制分析

全面总结、分析了岩石爆破过程S波的产生机制,表明短柱状药包、炮孔周围岩体的开裂与破碎以及装药偏离球形或柱形空腔中心,均可诱发S波,并且诱发S波的幅值可超过P波;P波传播过程与岩体界面的相互作用,可产生次生的S波（透、反射SV波）。在此基础上,就爆破振动场模拟方法与计算模型选择中如何体现S波的产生机制方面提出了建议     

波—流相互作用机制与复合流的沉积构造鉴别标志*

波—流相互作用是复杂水动力条件下流体相互作用的主要方式之一,由波—流相互作用形成的复合流沉积是目前沉积学在流体相互作用这一领域研究较多的一种沉积类型。以已有的文献为基础,对波—流相互作用下细砂级颗粒的运动机制进行了综述,预测了波—流相互作用的沉积特征,总结了复合流的沉积构造鉴别标志。取得的主要认识有: (1)波—流相互作用总体上属于衰弱流(waning flow)悬浮沉积,其微观的沉积机制可分为5种: 越过崩落点的喷射沉积(S1)、残余涡动沉积(S2)、未到崩落点的喷射沉积(S3)、背流面的崩落沉积(S4)、垂直降落沉积(S5);(2)波—流相互作用的沉积过程总体上受悬砂量和沉积时间的控制,5种微观沉积机制在不同的悬砂量和沉积时间条件下可形成不同的沉积机制组合,从而导致不同的底床形态;(3)复合流沉积构造鉴别标志主要有: 复合流波痕、复合流层理、爬升型复合流层理、不对称丘状交错层理、准平行层理和频繁交替的不能充分发育的浪成波纹层理与流水层理等6类。上述认识对于复杂水动力条件下的沉积学研究及对深水、浅水沉积环境的识别均具有重要的意义。     

非线性波动的几个基本问题

将非线性波动理论的研究划分为观察和分析、方程建立、初边值问题、解析解和数值解、非线性波动特征以及实际应用等六个大的研究方向，详细评述了各个方向的研究情况。提出了多层介质中的非线性波传播等尚未研究的问题，发现了用通常方法求取的解析解复杂、不易应用等问题，并提出了在定性的基础上省略与已知物理特征不符项的方法来求取解析解等思路。认为介质的非线性、各向异性、多相性应统一研究。     

基于遗传算法的扩散波洪水演算参数的确定方法

大量的理论分析和实际洪水演算表明,扩散波方法是一种既具有足够精度又相对简单的一类洪水演算方法。以线性扩散波方程在自由下边界条件下的解析解为例,利用遗传算法来确定扩散波方程的参数。遗传算法和一般的优化算法不同,它具有全局寻优能力,一般能得到问题的最优解或准最优解,是一类优秀的非线性函数优化方法。实例计算结果表明,采用遗传算法所得到的参数精度较高,可以类推到其它水文模型的参数率定中去。     

铌—酒石酸—偶氮氯膦—MN络合物极谱催化波的研究

在HNO_3介质中的Nb(V)-酒石酸-偶氮氯膦-mN络合物有一灵敏的催化波,峰电位为-0.81V(vs·SCE),Nb_2O_5浓度在0.002～0.16μg/ml范围与峰电流成线性关系。用有关电化学方法探讨了催化波的性质,表明该波为络合吸附催化波,拟定了一个不经分离,在样品分解后直接测定试液中痕量Nb的方法。     

应力波与可滑移岩石界面间的相互作用研究

研究了应力波与用节理刚度系数描述的线性滑移岩石界面间的相互作用，给出了其透、反射波幅的一般表达式。通过应力波垂直人射界面时的具体分析，反映出岩石界面的节理刚度对应力波传播的重要影响，并揭示了岩石界面对应力波的高频滤波作用。     

中国及邻近陆海地区软流圈三维结构及其与岩石圈的相互作用

通过中国及邻近陆海地区天然地震面波层析成像三维Vs速度结构的系统地质构造解析,笔者论述了中国及邻近陆海地区软流圈三维结构特征,发现该区软流圈内既有高速块体,又有低速异常体,显示软流圈内存在纵向与横向上的不均匀性,研究软流圈内低速异常体三维几何结构表明,南海低速异常体呈复蘑菇状,结合地幔体波层析成像研究显示,南海地区存在巨型复蘑菇状地幔低速柱头。笔者还探讨了软流圈对岩石圈结构的影响及其相互作用问题。     

基于双相介质弹性波波场分离的逆时偏移方法

随着地震勘探的发展,以单相介质模型为基础的声波逆时偏移和弹性波逆时偏移很难比较精确地描述地下介质和满足复杂的工程要求,尤其是在处理地下含流体多孔介质时,所以需要引入双相介质模型。首先基于Biot理论双相介质一阶速度-应力弹性波方程,利用散度场和旋度场的波场分离理论将固相和流相中的纵横波场解耦分离,并由波场快照图得出固相与流相中的纵波波场与横波波场均完成分离,而快纵波与慢纵波相互耦合均存在于纵波波场中。采用高阶交错网格有限差分方法,结合PML吸收边界条件,推导了具有波场分离的双相介质弹性波正传与反传的偏移延拓算子,结合互相关成像条件,可以得到双相介质弹性波固相与流相中的各分量偏移成像剖面。最后对模型使用该双相介质弹性波波场分离的逆时偏移方法进行偏移成像试算并取得成功,效果较常规双相介质弹性波逆时偏移成像效果有了明显提升。     

A semi-analytical method for the wave-induced seabed response

A general semi-analytical method is presented for the analysis of seabed response under wave action during a storm. The seabed is idealized as a poro-elastic medium filled with a single compressible fluid with anisotropic flow. The coupled process of fluid flow and deformation of soil skeleton is formulated in the framework of Biot's theory. The analysis for the response of homogeneous seabed of finite thickness under a plane progressive wave is developed first, followed by an extension for the case of a layered seabed. A generalization for three-dimensional response of seabed is also developed for a general wave field which provides the analyses for seabed response under short-crested or standing waves in the vicinity of a structure. Some numerical examples illustrating the proposed analyses are also presented.     

Short-crested wave-induced soil response in a porous seabed of infinite thickness

Waves reflecting obliquely from structures establish short-crested waves which are conducive to scour of the bed adjacent to them. The pore pressures and effective stresses induced by this wave system are derived analytically for an unsaturated, anisotropic soil matrix of infinite depth in a three-dimensional domain. Verification is available by the solutions being readily reduced to the two-dimensional cases of the progressive and standing wave, for which some closed-form solutions are available. It is shown that wave obliquity is coupled with soil permeability. The effects of wave obliquity, relative water depth, soil stiffness and soil permeability on wave-induced pore pressure are discussed in detail.     

表面波有效相速度近似分析方法

分层介质中瑞利面波有多个模态,表面瞬态响应是多个模态响应的叠加。在近场,面波模态响应传播速度随传播距离而变化;在远场,其趋于模态相速度。由分层介质表面两不同点响应互谱分析(SASW)得到的有效相速度并不对应于面波基阶模态相速度,它与波场中高阶模态能量分配比例有关。有效相速度随传播距离而变化,近场体波对有效相速度影响较大。对分层介质在简谐荷载下表面质点位移响应进行了互谱分析,得到了有效相速度理论值,通过理论值与测试值匹配分析可估算分层参数,该分析方法考虑了近场及高阶面波模态对有效相速度的影响。     

Effect of vorticity on the generation of rogue waves due to dispersive focusing

The kinematic and dynamic of steep two-dimensional focusing wave trains on a shearing flow in deep water are investigated analytically and numerically. In the absence of waves, the vorticity due to the vertical gradient of the horizontal current velocity is assumed constant. A linear kinematic model based on the spatio-temporal evolution of the frequency is derived, predicting the focusing distance and time of a chirped wave packet in the presence of constant vorticity. Furthermore, a linear model, based on a Fourier integral, is used to describe the evolution of the free surface on shearing current. To compute the fully nonlinear evolution of the wave group in the presence of vorticity, a new numerical model, based on a BIEM approach, is developed. On the basis of these different approaches, the role of constant vorticity on rogue wave occurrence is analysed. Two main results are obtained: (1) the linear behaviour expected in the presence of constant vorticity is significantly different from what is commonly expected in the presence of constant current and (2) the nonlinear effects are found to be of significant influence in the case at hand.     

Some kinematic features of refracted waves

The equation for the arrival time of a refracted wave is fully stated. This approximates as the arrival of the head wave minus the second and third terms of the equation. Time-distance curves are studied, and examples for carbonates, Precambrian, and crystalline specimens are given. Along with the linear velocity law, the parabolic law is also treated. Peculiarities of propagation of refracted waves in the medium are studied and depth of penetration is considered. Relations for refracted, diffracted, and reflected waves are examined and multiple refracted waves are considered as well. This seems to be a practical and general paper illuminating the refraction phenomenon. — Petroleum Abstracts.     

Impacts of a Wave Farm on Waves,Currents and Coastal Morphology in South West England

This study investigates impacts of a wave farm on waves, currents and coastal morphology adjacent to the wave farm, which is located in the Southwest of England (the Wave Hub). In this study, we focus on the interaction between waves and tides due to the presence of the wave farm and its effects on wave radiation stresses, bottom shear stresses and consequently on the sediment transport and the coast adjacent to the wave farm, using an integrated numerical modelling system. The modelling system consists of the near-shore wave model SWAN, the ocean circulation model ROMS and a sediment transport model for morphological evolution. The results show that tidal elevation and tidal currents can have a significant effect on waves and that tidal forcing and waves have a significant effect on bottom shear stresses. Waves can impact on the processes related to the bottom boundary layer and mixing intensity in the water column. The wave farm has an impact on the gradients of radiation shear stresses and bottom shear stresses that modify current speeds and wave heights, which in turn impact on the near-shore sediment transport and the resulting morphological changes. Bed load transport rates show a decrease when the wave farm is present, even during storm conditions. The results highlight the importance of the interactions between waves and tides when modelling coastal morphology with presence of wave energy devices.     

Analysis of Blast Wave Interaction with a Rock Joint

The interaction between rock joints and blast waves is crucial in rock engineering when rock mass is suffered from artificial or accidental explosions, bursts or weapon attacks. Based on the conservation of momentum at the wave fronts and the displacement discontinuity method, quantitative analysis for the interaction between obliquely incident P- or S-blast wave and a linear elastic rock joint is carried out in the present study, so as to deduce a wave propagation equation. For some special cases, such as normal or tangential incidence, rigid or weak joint, the analytical solution of the stress wave interaction with a rock joint is obtained by simplifying the wave propagation equation. By verification, it is found that the transmission and reflection coefficients from the wave propagation equation agree very well with the existing results. Parametric studies are then conducted to evaluate the effects of the joint stiffness and incident waves on wave transmission and reflection. The wave propagation equation derived in the present study can be straightforwardly extended for different incident waveforms and nonlinear rock joints to calculate the transmitted and reflected waves without mathematical methods such as the Fourier and inverse Fourier transforms.     

Numerical study of sediment transport above rippled beds under the action of combined waves and currents

To study sediment suspension above ripples under the combined action of waves and currents, a three‐dimensional numerical model has been developed based on the use of FLUENT software, and an external sediment transport model. The computer model has been tested against laboratory measurements involving oscillatory wave motion, as well as cases of co‐linear waves with following and opposing currents, with satisfactory results. Compared with the situation in which only waves are present (called waves‐alone cases), the effects from the steady current on both vortex shedding and sediment suspension above ripples have clearly been revealed by the model results. In particular, the vortices generated in combined waves and currents tend to stay low in the trough area of the ripple and are ejected earlier than those in the waves‐alone case at both the ripple crest and trough, which leads to concentration peaks at different phases and with different magnitudes. The model was also applied to a field case from a multi‐barred, dissipative beach at Egmond‐an‐Zee, in the Netherlands, to investigate the influences of a long‐shore current on cross‐shore sediment transport. The model results show reasonable overall agreement with the field measurements, as well as the important effects of the three dimensional flow structure on the sediment entrainment process close to the ripple surface, which is very difficult to observe in such detail in field studies.     

Recent Process in Near-Space Gravity Wave Analysis Based on Satellite Measurements

This article focused on the research progress in the gravity wave analysis based on satellite measurements including MODIS, AIRS, AMSU, MLS, DNB, COSMIC,HIRDLS and SOFIE. Besides, a few ground-based observation results and numerical models were briefly introduced and some cases of joint applications of satellite observations with ground-based observations and numerical models in the gravity waves were listed. In general, the satellite remote sensing data play an important role in the study of the characteristics in near-space environment, which can be applied to analyze the scales of gravity waves induced by different sources, correlations between the instabilities and waves as well as their patterns, the impacts in the climate process, wave-wave interactions and wave-flow interactions with other data.     

鄂尔多斯盆地西缘上奥陶统拉什仲组内波和内潮汐沉积成因分析

虽然地层记录中的内波和内潮汐沉积研究已有30年的研究历史,但尚未涉及深水环境中内波和内潮汐成因研究,不利于对深水复杂水动力环境下各种流体交互作用的深入研究,同时由于已发现研究实例中缺乏生物化石和遗迹化石,从而在很大程度上限制了对内波和内潮汐沉积和油气生成及运移之间的关系研究。本文以鄂尔多斯盆地西缘北部桌子山地区上奥陶统拉什仲组深水沉积为研究对象,在详细的野外观察基础上,采用沉积地球化学和沉积学相结合的方法对该组中发育的内波和内潮汐沉积进行了综合研究。结果表明：拉什仲组中的双向交错层理和浪成波纹层理可相互伴生,多发育在完全或近于完全的鲍玛序列T_c段,其寄主岩性主要为灰绿色薄-中层细砂岩、粉砂岩、黏土质粉砂岩和粉砂质黏土岩;沉积时水体介质具有海水性质总体上不明显、氧化-还原分层、盐度倒置、不受热液影响和水动力较强等现象。结合拉什仲组存在的浊流反射现象认为：拉什仲组沉积于局限海深水斜坡至盆地环境,其内波和内潮汐的形成与低密度浊流反射形成的密度跃层密切相关,具有事件性作用特征,并伴生有大量的生物化石(笔石)及遗迹化石。这种新型内波和内潮汐沉积对于深水牵引流沉积油气勘探具有...