Numerical study on the bifurcation of the North Equatorial Current

A 1.5-layer reduced-gravity model forced by wind stress is used to study the bifurcations of the North Equatorial Current(NEC).The authors found that after removing the Ekman drift,the modelled circulations can serve well as a proxy of the SODA circulations on the σθ=25.0 kg m～-3 potential density surface based on available long-term reanalysis wind stress data.The modelled results show that the location of the western boundary bifurcation of the NEC depends on both zonal averaged and local zero wind stress curl latitude.The effects of the anomalous wind stress curl added in different areas are also investigated and it is found that they can change the strength of the Mindanao Eddy(ME),and then influence the interior pathway.     

冬季寒潮期间黄、渤海水位低频波动研究

利用 POM(Princeton Ocean Model)海洋数值模式建立渤、黄、东海冬季三维环流动力学区域模型。模型在海-气边界使用包括风应力、气压和热通量的大气驱动, 海洋边界使用西太平洋模式提供的环流和潮位驱动, 综合模拟潮波运动、温度、盐度、环流变化和水位低频波动。 模拟了 2001 年 1 月寒潮过境时黄、 渤海水位低频波动及流场变化, 分析了其对大风过程、 气压、降温的响应, 发现冬季强劲的北风和西北风都可以通过抽吸振荡在渤、 黄海诱发水位的低频波动, 东北风则由于地形影响不能诱发渤、黄海的低频波动。气压和降温只是在波动幅度上有一定的影响。波动发源于渤海和北黄海, 最大波幅可以达到 0.6 m。波动进入南黄海后有沿黄海深槽西侧传播的倾向, 波动幅度在传播过程中逐渐减小。     

The effect of wave-induced radiation stress on storm surge during Typhoon Saomai (2006)

The effects of wave-induced radiation stress on storm surge were simulated during Typhoon Saomai using a wave-current coupled model based on ROMS (Regional Ocean Modeling System) ocean model and SWAN (Simulating Waves Nearshore) wave model.The results show that radiation stress can cause both set-up and set-down in the storm surge.Wave-induced set-up near the coast can be explained by decreasing significant wave heights as the waves propagate shoreward in an approximately uniform direction;wave-induced set-down far from the coast can be explained by the waves propagating in an approximately uniform direction with increasing significant wave heights.The shoreward radiation stress is the essential reason for the wave-induced set-up along the coast.The occurrence of set-down can be also explained by the divergence of the radiation stress.The maximum wave-induced set-up occurs on the right side of the Typhoon path,whereas the maximum wave induced set-down occurs on the left side.     

辐射应力对台风风暴潮预报的影响和数值研究

台风过程期间,风暴潮和海浪是相伴相生的,相互作用的.波致辐射应力对于近岸风暴增、减水起着十分重要的作用,传统的海浪模式计算辐射应力耗时较多,不能满足业务化预报的要求.根据已有波浪辐射应力的理论表达式,经过严密的数学推导,适当的简化处理,提出了一个较为简单的波浪辐射应力表达式,并将其应用到业务化风暴潮数值预报模式中去,通...     

发扬李四光地震预报的科学思想

李四光教授关于地震地质工作中地震预报方面的重要观点和思想主要包括:地应力变化与地震密切相关;地震活动带中也存在相对安全的地区(“安全岛”理论);地震地质调查是地震预报的基础;地震是可以预测的,地应力的变化过程是地震预报的关键.他的“安全岛”理论及地震预报思想至今仍有着十分重要的理论意义和现实意义.     

单桩复合地基静载荷试验系统的设计与应用研究

复合地基是通过褥垫层的调整作用,充分发挥桩间土的承载作用,使桩土共同承担荷载的地基。基于复合地基的实际工况,设计了一种单桩复合地基静载荷试验系统,既体现了褥垫层的调整作用,又可测得复合地基中桩体、桩问土、复合地基的荷载与其相应的沉降,同时可得出复合地基受力过程中桩土荷载分配过程与桩土应力比,提示了复合地基工作机理。通过工程实例测试,探讨了复合地基的工作机制,为复合地基的科研、设计与检测提供了依据。     

胶东大磨曲家金矿床岩石磁组构、构造变形与金矿化

在胶东地区招远-平度断裂带上的大磨曲家金矿区选取了典型的构造区域进行岩石磁组构研究。沿着断裂带在不同构造部位的36个采样点钻取了112个定向岩心样品,所有样品均沿勘探线布置。磁组构研究显示,研究区以弱磁性岩石为主,总体上,胶东群变质岩的磁化率值较高,而玲珑黑云母花岗岩的磁化率值较低,尤以碎裂程度高的强蚀变岩的磁化率值最低;磁化率各向异性方位主要为NE向挤压,磁组构所指示的构造应力场与大磨曲家矿区的区域挤压应力方向是相同的;对具不同程度矿化的81线的Au含量与80线磁组构各向异性度(P值)进行对比研究发现,P值与金品位呈负相关关系;弱矿化糜棱岩中的金矿化在磁面理发育的岩石中较为发育,成矿晚期,Au元素含量随着岩石磁性的减弱而增加,特别是在强应变后弛豫阶段矿液充填于相对张性的石英脉中Au含量最高。     

江西临川地区相山铀矿田构造应力场分析

相山铀矿田是中国最大的、与火成岩有关的中低温热液型矿床,断裂构造控矿特征明显。目前该矿床的后备资源出现危机,因此开展矿田构造研究,为深部及其外围找矿提供科学指导迫在眉睫。在野外观测分析和节理、擦痕实地测量的基础上,利用构造解析法、共轭剪节理分析法、断层擦痕反演模拟法及X光岩组法等,通过吴氏网投图分析和计算机的反演计算,确定了相山铀矿田多期次构造活动的变形特征及其主应力方向;并根据构造变形叠加关系及其成岩时代的确定,推断了应力作用的期次和时代。为此,将相山铀矿田的构造应力场划分为3期6个阶段,包括：成矿前的基底变形和早期火山活动阶段,早期矿化蚀变和第一、第二主成矿阶段,及其成矿期后阶段,矿体局部被错断;并深入分析了不同阶段构造活动及其铀成矿特征,探讨了区域构造应力场的演变与铀成矿作用关系,认为两者具有一致性特征,进而指出了区域富大矿体产出的有利构造部位。     

渭北煤田合阳县北中深部控煤构造样式分析

依据野外地表地质观测及地震、钻探最新的深部地质资料,结合对区域控煤构造认识,运用构造解析、构造应力场及地质力学分析等研究思路与方法,讨论了研究区控煤构造特征、构造样式以及成因。研究结果表明：研究区共有三类六种控煤构造样式,即挤压构造样式（宽缓褶皱、叠加褶皱）、走滑构造样式（反＂S＂型褶皱、＂入＂字型构造）及伸展构造样式（掀斜断块、堑垒构造）,其中以伸展构造样式发育为主要特征;研究区由东南向西北,构造变形强度由强变弱,先后经历了印支期南北向挤压、燕山中期北西向挤压和喜马拉雅期北东向挤压-走滑与北西-南东向伸展断陷作用;晚期形成的正断层不仅破坏了煤层的连续性,而且成为奥灰水储集和运移的主要通道,增大了底板突水的可能性,使煤炭资源开发受到影响。     

Stress state in the Cuu Long and Nam Con Son basins, offshore Vietnam

The results presented in this paper are the first published estimates of the complete stress tensor in the Cuu Long and Nam Con Son basins, offshore Vietnam. We analysed in situ stress and pore pressure fields in the sedimentary formations using data from petroleum exploration and production wells to evaluate the stress state in these basins. The data were obtained from the seafloor to 4300 m burial depth and include both hydrostatic and overpressured sections. Minimum horizontal stresses were obtained from extended leak-off tests and mini-fracture tests. Maximum horizontal stresses were estimated from drilling-induced fracture parameters and borehole breakout widths in twelve wells using rock properties measured in the laboratory or estimated empirically from wireline logs. Seven data points are located in sediments, and seventeen data points in igneous basement rocks at depths greater than 3000 m.The estimated magnitudes of σ_H are 70-110% of the σ_v magnitudes. Considering the errors in the stress magnitude estimates, their relative magnitudes suggest that a borderline normal/strike-slip stress regime presently exists in normally pressured sequences of the Nam Con Son and Cuu Long basins. Of the twenty-four data points, twenty have effective stress ratios at a critical stress state for faulting on the assumption that there are faults present that are optimally oriented for failure with friction coefficients of ∼0.5. The results suggest that the stress state in these basins is generally critical.