基于平面波解构滤波的速度无关动校正及速度分析方法

为了避免速度分析拾取速度参数引起的繁复费时、拾取参数不准确导致的校正效果不佳和传统动校正的拉伸畸变问题,利用速度无关动校正方法进行相关处理。通过数据解构获取局部同相轴斜率,解析斜率数据与速度的关系,由局部斜率可直接获得动校正所需时差参数,其信息足以进行动校正处理。通过模拟和实际数据进行的实验计算,证明此方法优于常规动校正处理效果。     

Mud dispersal across a Cretaceous prodelta: Storm‐generated,wave‐enhanced sediment gravity flows inferred from mudstone microtexture and microfacies

Determining sediment transport direction in ancient mudrocks is difficult. In order to determine both process and direction of mud transport, a portion of a well‐mapped Cretaceous delta system was studied. Oriented samples from outcrop represent prodelta environments from ca 10 to 120 km offshore. Oriented thin sections of mudstone, cut in three planes, allowed bed microstructure and palaeoflow directions to be determined. Clay mineral platelets are packaged in equant, face‐face aggregates 2 to 5 μm in diameter that have a random orientation; these aggregates may have formed through flocculation in fluid mud. Cohesive mud was eroded by storms to make intraclastic aggregates 5 to 20 μm in diameter. Mudstone beds are millimetre‐scale, and four microfacies are recognized: Well‐sorted siltstone forms millimetre‐scale combined‐flow ripples overlying scoured surfaces; deposition was from turbulent combined flow. Silt‐streaked claystone comprises parallel, sub‐millimetre laminae of siliceous silt and clay aggregates sorted by shear in the boundary layer beneath a wave‐supported gravity flow of fluid mud. Silty claystone comprises fine siliceous silt grains floating in a matrix of clay and was deposited by vertical settling as fluid mud gelled under minimal current shear. Homogeneous clay‐rich mudstone has little silt and may represent late‐stage settling of fluid mud, or settling from wave‐dissipated fluid mud. It is difficult or impossible to correlate millimetre‐scale beds between thin sections from the same sample, spaced only ca 20 mm apart, due to lateral facies change and localized scour and fill. Combined‐flow ripples in siltstone show strong preferred migration directly down the regional prodelta slope, estimated at ca 1 : 1000. Ripple migration was effected by drag exerted by an overlying layer of downslope‐flowing, wave‐supported fluid mud. In the upper part of the studied section, centimetre‐scale interbeds of very fine to fine‐grained sandstone show wave ripple crests trending shore normal, whereas combined‐flow ripples migrated obliquely alongshore and offshore. Storm winds blowing from the north‐east drove shore‐oblique geostrophic sand transport whereas simultaneously, wave‐supported flows of fluid mud travelled downslope under the influence of gravity. Effective wave base for sand, estimated at ca 40 m, intersected the prodelta surface ca 80 km offshore whereas wave base for mud was at ca 70 m and lay ca 120 km offshore. Small‐scale bioturbation of mud beds co‐occurs with interbedded sandstone but stratigraphically lower, sand‐free mudstone has few or no signs of benthic fauna. It is likely that a combination of soupground substrate, frequent storm emplacement of fluid mud, low nutrient availability and possibly reduced bottom‐water oxygen content collectively inhibited benthic fauna in the distal prodelta.     

声波测试法在判别地下厂房EDZ中的应用

洞室开挖不可避免地会损伤岩体, 对于规模巨大、布置异常复杂的水电地下厂房围岩尤甚, 合理地确定开控损伤区(EDZ)分布成为地下洞室的信息化设计、施工和安全运营的关键性问题.在引入EDZ概念及强EDZ、弱EDZ和基本未损区分区的基础上, 提出采用声波测试方法来确定强EDZ和弱EDZ的分布.将声波波速-深度曲线划分为Ⅰ型、Ⅱ型和Ⅲ型等3种曲线类型, 根据曲线特征点, 对EDZ进行定性、半定量的初判.根据波速计算得出的损伤因子D, 对强、弱EDZ和基本未损区进行定量的判别.首次提出的基于声波测试法, 定性、半定量和定量相结合的综合研判法具有创新性, 为客观评价地下洞室EDZ提供了科学的方法.      

爆炸地震波作用下盾构隧道动力响应分析

盾构隧道衬砌由于各种类型接头的存在而与整体式衬砌的力学特性存在较大差异。将盾构隧道衬砌结构看作由弹塑性铰链连接的刚性管片组成,考虑围岩介质的黏弹性,提出了爆炸地震波作用下盾构隧道动力分析的简化计算方法。采用该方法对南京地铁盾构段典型横断面进行了动力分析,研究了爆炸地震波入射角度、围岩介质特性及管片厚度对结构受力与变形的影响规律。分析结果表明:波入射角度对盾构隧道有很大影响,斜入射时结构的动力响应要大于垂直入射时结构的动力响应;围岩介质等级越高,围岩对隧道结构的约束越强,隧道的抗爆性能越好;管片厚度的增大会增大结构的内力,合理设置管片厚度有利于提高盾构隧道抗爆性能。     

花山岩画开裂岩体声波测试与分析

阐述了声波测试的方法和过程,通过在岩体中声波的传播速度,建立开裂岩体厚度与劣化程度的数学模型。结果表明,开裂岩体厚度小于30 mm时,强度损失较大;开裂岩体厚度大于30 mm时,强度基本保持不变,为今后花山岩画的保护提供科学可靠的理论依据。     

Empirical formula for wave length of ocean wave in finite depth water

In this paper, function characteristics of dispersion of ocean wave in finite depth water were analyzed systematically. The functional form of the fitting function is reasonably proposed, in which the parameters are optimally determined by the least square method （LSM）. For infinitely deep and extremely shallow water,the fitting function fits strictly the dispersion to be fitted. A new technique is presented in application of LSM.An empirical formula with maximum error of less than 0.5% for computing wavelength in finite depth water is presented for practical applications.     

通海台垂直摆受建筑载荷影响的数值模拟研究

针对通海台垂直摆NS和EW测项自2019-04出现同步趋势转折变化,计算2017~2020年NS和EW测项M₂波潮汐因子。结合监测井等地下介质结构资料,构建通海台沿垂向分层的三维有限元物理模型,定量分析不同岩石参数模型下建筑载荷对通海台NS向及EW向位移影响的差异特征。结果表明：1）2019-04后NS测项N倾变化量达到约2 750 ms,而EW测项E倾变化量达到约580 ms,NS测项趋势变化量显著大于EW测项;2）2017~2020年NS和EW测项M₂波潮汐因子较为稳定,NS测项M₂波潮汐因子在0.7左右波动,EW测项M₂波潮汐因子在0.52左右波动,数据的转折变化未能在潮汐频段引起同步变化;3）位于通海台东北部的医院建筑物载荷在通海台附近产生N向和E向位移加载,与垂直摆NS和EW测项在2019-04后出现的N倾和E倾趋势转折变化较为一致,模拟得到的N向位移量约为E向位移量的3倍。     

热源强迫的非线性惯性重力内波及其应用

利用动力学分析中的相平面方法,由z坐标系下的非绝热大气运动方程组导出了与非线性惯性重力内波有关的KdV方程,然后利用直接积分法得到两类有天气意义的孤立波解.初步建立了孤立波解与高原低涡的联系,进一步从理论上论证了高原低涡具有与热带气旋类低涡类似的涡眼和暖心结构的特征.     

Analysis on monthly-averaged distribution of sea surface wind and wave over the seas southeast of Asia using ERS-2 scatterometer data

The wind system over the seas southeast of Asia (SSEA) plays an important role in China's climate variation. In this paper, ERS scatterometer winds covering the period from January 2000 to December 2000 and the area of 2-41 °N, 105- 130°E were analyzed with a distance-weighting interpolation method and the monthly mean distribution of the sea surface wind speed were given. The seasonal characteristics of winds in the SSEA were analyzed. Based on WAVEWATCH Ⅲ model, distribution of significant wave height was calculated.     

Scattering of elastic wave by a partially sealed cylindrical shell embedded in poroelastic medium

Scattering of an elastic wave by a cylindrical shell embedded in poroelastic medium is investigated theoretically with the assumption that the shell material is also a porous elastic medium. The porous medium is modellized via Biot's theory and the scattering by cylindrical shell is expressed by the definition of scattering matrix. The normal mode expansion technique is employed for analysing the scattering field, and the asymptotic solutions of displacements, stresses and pore pressure are derived. Two limiting cases‐scattering by a poroelastic cylinder in Biot medium and a elastic cylindrical shell in elastic medium are obtained from the general solutions. The dispersion curves of displacement amplitude at the interface of shell and medium is compared with the case of elastic shell. The scattering amplitude associated with the fast, slow and transverse waves are identified by numerical simulation. Furthermore, the influence of the poroelastic property of shell material on scattering amplitude is analysed. Copyright © 2005 John Wiley & Sons, Ltd.