三维复杂结构Spar平台垂荡板垂荡水动力性能研究

对三维复杂结构Spar平台垂荡板进行垂荡运动的数值模拟,并对垂荡板附近流场及水动力系数进行对比分析。结果表明:在主板尺寸相同情况下,主板边缘附近较小的角钢结构会对垂荡板流场产生明显影响,并导致水动力性能的较大差距;水动力系数计算结果与流场分析的结论一致。虽然复杂板架结构的三维建模及网格划分难度很大,但是在Spar平台垂荡板工程设计中不能完全采用简化光滑平板代替真实、复杂结构形式的垂荡板进行水动力性能的计算。     

Acoustic Ray-Trace Equations for Seafloor Geodesy

One goal of seafloor geodesy is to measure horizontal deformation of the seafloor with millimeter resolution. A common technique precisely times an acoustic signal propagating between two points to estimate distance and then repeats the measurement over time. The accuracy of the distance estimate depends upon the travel time resolution, sound speed uncertainty, and the degree to which the path computed from propagation equations replicates the actual path traveled by the signal. In this paper, we address the error from ray propagation equations by comparing three approximations to Snell's Law with ellipsoidal geometry.     

浅谈中国大陆东缘中生代地质演化与泛太平洋板块活动的关系

本文旨在厘清中生代中国东缘受泛太平洋板块俯冲作用影响下,其可能形成的地质记录的时空分布与泛太平洋板块活动的关系。前者主要从岩浆、构造、沉积盆地的时空演化等角度出发,后者的运动学参数集中在俯冲角度、速度、方向等维度。结果显示：俯冲角度、速度以及方向的改变都有可能形成与之对应的地质事件;但是中国东缘（东北、华北和华南）区域地质记录间的差异也表明,即使都可能遭受俯冲作用,由于个体特殊的构造背景,最终的结果也不尽相同。我们对于中国东缘中、新生代的这一特殊构造现象进行了讨论,得出如下结论：首先三联点力学稳定性分析结果认为,在华北和华南碰撞拼合后,中国大陆东缘可能存在TTT、TTR或者TFT的三联点,而不是简单的稳定的被动大陆边缘;另外,中国华南早、中侏罗世近东西向岩浆岩的形成可能与法拉隆板块和伊泽奈岐板块洋中脊俯冲有关;晚侏罗-早白垩世的板片后撤由NWW向的伊泽奈岐板块与太平洋板块的洋中脊扩张作用所致;而华北克拉通东部记录侏罗纪伊泽奈岐板块俯冲的证据不足,可能并没有发生板块俯冲作用,表现为板块运动与作为中国东部最为薄弱地区的郯庐断裂带的强烈耦合作用。     

Late Miocene to present-day exhumation and uplift of the Internal Zone of the Rif chain: Insights from low temperature thermochronometry and basin analysis

Located on the margin of the west Alboran basin, the Gibraltar Arc (Betic-Rif mountain belt) displays post-Pliocene vertical movements evidenced by uplifted marine sedimentary basins and marine terraces. Quantification of vertical movements is an important clue to understand the origin of present-day relief generation in the Betic-Rif mountain chain together with the causes of the Messinian Salinity Crisis. In this paper, we present the results of a pluridisciplinary study combining an analysis of low temperature thermochronology and Pliocene basins evolution to constrain the exhumation history and surface uplift of internals units of the Rif belt (Northern Morocco). The mean (U-Th)/He apatite ages obtained from 11 samples are comprised between 14.1 and 17.8 Ma and display a wide dispersion, which could be explained by a great variability of apatite chemistries in the analyzed samples. No correlations between altitude and age have been found along altitudinal profile suggesting a rapid exhumation during this period. Thermal modeling using our (U-Th)/He apatite ages and geochronological data previously obtained in the same area (⁴⁰Ar/³⁹Ar and K/Ar data on biotite, zircon and apatite fission track) allow us to propose a cooling history. The rocks suffered a rapid cooling at 60–100 °C/Ma between 22.5 and 19 Ma, then cooled to temperatures around 40 °C between 19 and 18 Ma. They were re-heated at around 110 °C between 18 and 15 Ma then rapidly cooled and exhumed to reach the surface temperature at around 13 Ma. The re-heating could be related to a renewal in thrusting and burying of the inner zones. Between 15 and 13 Ma the cooling resumed at a rate of 50 °C/Ma indicating an exhumation rate of 0.8 mm/y considering an average 40 °C/km geothermal gradient. This exhumation may be linked to the extension in the Alboran Sea. Otherwise biostratigraphic and sedimentological analysis of Pliocene basins of the internal Rif provided informations on the more recent events and vertical movements. Pliocene deposits of the Rifian coast represent the passive infilling of palaeo-rias between 5.33 and 3.8 Ma. The whole coastal area was uplifted at slow average rates (0.01–0.03 mm/y) in relation with a northeastward tilting of 0.2–0.3° since the Lower-Pliocene. A late Pliocene to present extensional tectonics associated to uplift has been identified all along the coastal ranges of the Internal Zone of the Rif chain. This extension was coeval with the major late Pliocene to Pleistocene extensional episode of the Alboran Sea and appears to be still active nowadays. No significant late Messinian uplift was evidenced, thus calling into question the geodynamic models relating the closure of the marine gateways and the MSC to slab roll back.     

防屈曲开斜槽耗能钢板剪力墙的滞回性能分析

防屈曲开斜槽耗能钢板剪力墙（简称开斜槽剪力墙）是通过在钢板上开设一定数量斜槽,并在其两侧外挂混凝土板而形成的一种新型高层钢结构抗侧耗能构件。根据开斜槽钢板剪力墙的承载机制,采用理论推导的方法得到其承载力计算公式,利用ANSYS有限元方法对开斜槽剪力墙进行模拟,并通过改变不同参数验证了计算公式的准确性。同时,采用ANSYS建立有限元模型,对开斜槽剪力墙和普通薄钢板剪力墙的滞回性能进行了对比分析。结果表明,在提供足够约束（钢板与混凝土板间隙适宜,混凝土板厚度足够）的前提下,相对于普通薄钢板剪力墙,开斜槽剪力墙改善了钢板的捏缩现象,具有更稳定的耗能能力。     

Upper mantle anisotropy and crust-mantle deformation pattern beneath the Chinese mainland

Over the past 10 years,the number of broadband seismic stations in China has increased significantly.The broadband seismic records contain information about shear-wave splitting which plays an important role in revealing the upper mantle anisotropy in the Chinese mainland.Based on teleseismic SKS and SKKS phases recorded in the seismic stations,we used the analytical method of minimum transverse energy to determine the fast wave polarization direction and delay time of shear-wave splitting.We also collected results of shear-wave splitting in China and the surrounding regions from previously published papers.From the combined dataset we formed a shear-wave splitting dataset containing 1020 parameter pairs.These splitting parameters reveal the complexity of the upper mantle anisotropy image.Our statistical analysis indicates stronger upper mantle anisotropy in the Chinese mainland,with an average shear-wave time delay of 0.95 s;the anisotropy in the western region is slightly larger(1.01 s)than in the eastern region(0.92 s).On a larger scale,the SKS splitting and surface deformation data in the Tibetan Plateau and the Tianshan region jointly support the lithospheric deformation mode,i.e.the crust-lithospheric mantle coherent deformation.In eastern China,the average fast-wave direction is approximately parallel to the direction of the absolute plate motion;thus,the upper mantle anisotropy can be attributed to the asthenospheric flow.The area from the Ordos block to the Sichuan Basin in central China is the transition zone of deformation modes between the east and the west regions,where the anisotropy images are more complicated,exhibiting"fossil"anisotropy and/or two-layer anisotropy.The collision between the Indian Plate and the Eurasian Plate is the main factor of upper mantle anisotropy in the western region of the Chinese mainland,while the upper mantle anisotropy in the eastern region is related to the subduction of the Pacific Plate and the Philippine Sea Plate beneath the Eurasian Plate.     

板裂体组合条件下岩爆倾向性分析

针对已有突变理论仅对单块板裂岩体进行分析的局限性,提出将板裂化岩体作为整体进行研究,考虑了劈裂岩体间的水平应力,改进了突变理论模型在岩爆分析中的应用,并分别计算对比了单块岩板及板裂岩板组合在准静力及动力扰动两种条件下的岩爆倾向性。研究结果表明,准静力条件下单块岩板突变特征值?变化趋势平缓,而组合岩体由于等效抗弯刚度较大,? 急剧增大;准静力条件下岩板组合的岩爆深度明显大于单块岩板时,岩爆深度达到0.76 m;随岩板厚度增加,突变特征值?逐渐增大,不再满足岩爆的充分条件,施加竖向扰动应力即可重新满足突变条件,所需外界扰动应力由几兆帕增大至几十兆帕。     

安哥拉格埃路砂地层的承载力研究

安哥拉格埃路地层（Quelo）棕红色砂土形成年代较长,低含水率下地基承载力较高,但遇水后地基承载力降低幅度较大,地基处理方案常有争议。大量的工程实践和专项研究表明,地基土的承载力与含水率有明显的相关性,通过探井取样和原位测试,查明了地基土的物理力学特性,分析不同含水率条件下的静力触探试验(CPT)和平板载荷试验(PLT)数据,建立了适用于该地层的地基承载力与含水率的幂函数关系式以及地基承载力与锥头阻力的线性经验公式。静力触探试验结果表明,地层锥头阻力qc和侧壁摩阻力fs随深度增加而逐渐提高,土质均匀,但摩阻比Rf较小。分析认为,采用不经碾压的砂土作为地基,具有较高的风险;对于多层及9～13层建筑的地基处理,采用换填垫层法较桩基更合理。     

近断层速度脉冲地震动引起的边坡永久位移预测模型

基于小波分析方法,从NGA数据库的3 551条地震记录中选取189条速度脉冲地震动,地震动均转换成发生最强脉冲的方向。基于Newmark方法,分析了近断层速度脉冲地震动作用引起的边坡永久位移值。结果表明：近断层速度脉冲地震动对边坡产生特殊的破坏作用,表现在滑动位移值大、滑动体破坏力强等方面;边坡永久位移值与速度脉冲地震动的峰值速度具有高度相关性,位移值较大时尤为明显。建立了基于单变量形式的峰值速度及双变量形式的峰值速度、峰值加速度两种边坡永久位移预测模型,模型简单实用,与回归数据具有很好的相关性,前者更适用于预测对实际工程影响较大的永久位移值,且离散性较小。提出的预测模型为考虑近断层地震动速度脉冲特性影响的边坡永久位移值的概率地震灾害分析提供了基础。     

Inelastic spectra to predict period elongation of structures under earthquake loading

Period lengthening, exhibited by structures when subjected to strong ground motions, constitutes an implicit proxy of structural inelasticity and associated damage. However, the reliable prediction of the inelastic period is tedious and a multi‐parametric task, which is related to both epistemic and aleatory uncertainty. Along these lines, the objective of this paper is to investigate and quantify the elongated fundamental period of reinforced concrete structures using inelastic response spectra defined on the basis of the period shift ratio (T_in/T_el). Nonlinear oscillators of varying yield strength (expressed by the force reduction factor, R_y), post‐yield stiffness (a_y) and hysteretic laws are examined for a large number of strong motions. Constant‐strength, inelastic spectra in terms of T_in/T_el are calculated to assess the extent of period elongation for various levels of structural inelasticity. Moreover, the influence that structural characteristics (R_y, a_y and degrading level) and strong‐motion parameters (epicentral distance, frequency content and duration) exert on period lengthening are studied. Determined by regression analyses of the data obtained, simplified equations are proposed for period lengthening as a function of R_y and T_el. These equations may be used in the framework of the earthquake record selection and scaling. Copyright © 2015 John Wiley & Sons, Ltd.