双重约束条件下的连续重力观测非线性漂移改正方法分析

连续重力观测去除固体潮后所得重力残差结果,除了受仪器故障、自然因素、人为因素以及供电系统干扰外,弹簧重力仪的长期漂移也成为重力变化的重要影响因素,故漂移改正不可忽略。本文以高台地震台近5年的连续重力观测资料为数据基础,采用多阶多项式拟合法,并以驰豫分析结果和流动重力场结果为约束,研究弹簧重力仪的非线性漂移特征及其漂移改正的合理性。研究结果表明：高台重力仪的线性和非线性漂移特征明显,严重影响了其他微弱重力信号的提取,而驰豫分析处理结果和流动重力场成为有效地辅助约束手段,在其双重制约下进行非线性漂移改正,使所得重力非潮汐结果更为准确可靠,为地震预测预报提供较为准确的参考依据。     

宜昌台三类地倾斜仪观测数据的对比研究

研究采用宜昌地震台水管倾斜仪、VP型垂直摆倾斜仪、VS型垂直摆倾斜仪三类地倾斜仪的观测数据,进行潮汐响应函数和非潮汐参数和地震响应对比。结果显示:(1)三类倾斜仪M_2波潮汐因子NS向普遍小于EW向,NS向容易受局部观测环境的影响;三类倾斜仪EW向潮汐速率略大于NS向,VS仪漂移最大,其次VP仪,而水管仪三者中漂移最小。总的来说,仪器的稳定性和精度方面,水管仪最好,VP倾斜仪次之,垂直摆最低。(2)三类倾斜仪易受观测环境干扰,数据产生不同程度噪声,由于不同仪器的性能差异,造成三类观测数据不同步,为鉴别真实的地壳形变信息,应对观测数据做去干扰处理,将不同观测的物理量互相验证,对数据质量较差的观测系统应进行合理化改造。     

Seismic responses of bridges with rocking column-foundation: A dimensionless regression analysis

Rocking column-foundation system is a new design concept for bridges that can reduce overall seismic damage, minimize construction and repair time, and achieve lower cost in general. However, such system involves complex dynamic responses due to impacts and highly nonlinear rocking behavior. This study presents a dimensionless regression analysis to estimate the rocking and shaking responses of the flexible column-foundation system under near-fault ground motions. First, the transient drift and rocking responses of the system are solved numerically using previously established analytical models. Subsequently, the peak column drifts and uplift angles are derived as functions of ground motion characteristics and the geometric and dynamic parameters of column-foundation system in regressed dimensionless forms. The proposed response models are further examined by validating against the numerical simulations for several as-built bridge cases. It is shown that the proposed model not only physically quantifies the influences of prominent parameters, but also consistently reflects the complex dynamics of the system. The seismic demands of rocking column-foundation system can be realistically predicted directly from structural and ground motion characteristics. This can significantly benefit the design of bridges incorporating this new design concept.     

浮子数字水位仪动水位观测实验

针对投入式水位仪存在稳定性差、零漂大等缺点,研制浮子式JS-1数字水位仪,基于观测原理和仪器结构,在苏18井开展动水位观测实验,结果发现:JS-1数字水位仪在动水位观测中可行,产出数据质量优良,并且在对零漂控制、观测数据质量、观测精度等方面具有一定优势。     

无井波阻抗反演在西沙水合物研究中的应用

为了更好地研究水合物的展布形态和赋存情况,对西沙海域天然气水合物的准三维地震资料进行无井波阻抗反演。详细论证针对水合物无井波阻抗反演的处理方法:根据水合物的地球物理特征对地震资料进行零相位化处理;根据地震资料本身特征,在工区多个构造稳定区提取地震子波,对求取的子波平均化保证子波的稳定性;根据叠加速度,通过网格插值、平滑、滤波、转换求取三维低频阻抗模型。最终得到的反演结果地质现象清楚,能够较准确地反映水合物的空间展布情况,利于后续水合物的综合分析研究。      

Paraglacial modification of slope form

The morphological consequences of paraglacial modification of valley-side drift slopes are investigated at six sites in Norway. Here, paraglacial slope adjustment operates primarily through the development of gully systems, whereby glacigenic sediment is stripped from the upper drift slope and redeposited in debris cones downslope. This results in an overall lowering of average gradient by up to 4·5° along gully axes. In general, slope profile adjustment appears to be characterized by a convergence of slope profiles towards an ‘equilibrium form’ with an upper rectilinear slope gradient at 29°± 4° and a range of concavities of approximately 0·0 to 0·4. After initial rapid incision, further gully deepening is limited, but gullies become progressively wider as sidewall gradients decline to c. 25°, after which parallel retreat appears to predominate. The final form of mature paraglacial gully systems consists of an upper bedrock-floored source area, a mid-slope area of broad gullies whose sidewalls rest at stable, moderate gradients, and a lower slope zone where gullies discharge onto the surfaces of debris cones and fans. Some gullies appear to have attained this final form and have stabilized following exhaustion of readily entrainable sediment within decades of gully initiation. At most sites, paraglacial activity has transformed steep drift-mantled valley sides into gullied slopes where an average of c. 2–3 m of surface lowering has taken place. At the most active sites, these average amounts imply minimum erosion rates averaging c. 90 mm a⁻¹ since gully initiation, which highlights the extreme rapidity of paraglacial erosion of deglaciated drift-mantled slopes. Copyright © 1999 John Wiley & Sons, Ltd.     

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长江口宝钢码头溢油事故油膜漂移扩散数值模拟

溢油事故发生后,油膜的漂移扩散会对周围水域和环境敏感目标造成污染。研究溢油事故后油膜漂移扩散,可为溢油事故的处理提供理论指导。本文应用河口海岸三维水动力模式ECOM-si(semi-implicit estuarine,costal and ocean model),耦合溢油漂移扩散模块,模拟和分析长江口宝钢码头发生溢油事故后油膜的漂移扩散,以及对环境敏感保护目标的影响。基于长江口崇明东滩气象站实测风速风向资料,给出影响溢油漂移的主导风和不利风向。在冬季多年平均1月径流量11700m³·s^–1、主导风、3个不利风和潮汐作用下,数值模拟并详细给出了宝钢码头溢油事故发生后油膜的平面分布、油膜到达和离开4个水库取水口和饮用水水源保护区以及其他环境敏感保护区的时间、持续影响时间和最大油膜厚度。长江口宝钢码头溢油事故发生后,油膜随涨落潮流作上下游来回振荡,径流使油膜向海输运,风使油膜朝风向方向漂移。在主导风北风5.6m³·s^–1风速下,油膜沿长江口南岸向下游漂移扩散,小部分进入北槽南侧。在不利风向东南风4.0...     

Cluster探测到磁尾等离子体注入的特征

利用Cluster卫星2001～2004年磁尾运行期间RAPID仪器的数据,确定了115例磁尾等离子体注入事件,借助时序叠加法统计研究磁尾等离子体注入现象的特征.注入事件主要分布于磁地方时夜晚20时至凌晨04时.与同步轨道区观测到的粒子注入事件类似,可以将磁尾粒子注入事件分成五类：（1）只有离子注入;（2）离子先于电子注入;（3）离子和电子同时注入;（4）电子先于离子注入;（5）只有电子注入.磁尾粒子注入时,质子（能量范围0～40 keV）的温度和数密度同时显著增加,沿地球径向的传播速度也明显增大.统计分析磁尾注入期间同时观测到的晨昏对流电场,发现电场可分为两类：（A）注入后电场突然增大,电场强度为正;（B）注入后电场突然增大,电场强度为负.利用磁层磁场（T89c）和电场（Volland-Stern）模型模拟粒子注入后赤道面的电漂移速度矢量,模拟结果与统计结果基本一致,表明晨昏对流电场引起的电漂移是驱动磁尾（-18R_EE）等离子体沿地球径向注入的机制之一.     

Stokes漂流近似公式对海洋表层流场估算的影响

本文采用波浪订正的Ekman模型,研究分析了三种Stokes漂流近似公式(单波公式、e指数公式、Phillips谱近似公式)对海洋表层流场估算的影响。海表总流场由海表面高度(SSH)数据计算的地转流和海浪模式WAVEWATCH Ⅲ输出结果计算的非地转流组成,并采用拉格朗日浮标观测数据对计算结果进行了验证。研究表明,随着Stokes漂流近似公式精度的提高,其计算的拉格朗日流速更接近于谱积分公式的计算结果,更贴近拉格朗日浮标观测数据。与谱积分公式计算的海表拉格朗日流速相比,单波公式的平均相对偏差为0.0834,e指数公式的平均相对偏差为0.0392,Phillips谱近似公式的平均相对偏差为0.0101,说明Phillips谱近似公式在不同风速下均能对谱积分公式有良好的近似效果。在低风速条件下,由Stokes漂流近似公式精度引起的海洋表层流场估算误差可以忽略不计,但随着风速增加,由近似公式精度引起的偏差逐渐变大,此时应该选择Phillips谱近似公式计算Stokes漂流,来减小误差。