Numerical Simulation of Wave Forces on Seabed Pipelines

A three-step finite element method(FEM)together with Large Eddy Simulation(LES)is ap-plied to incompressible turbulent flow around seabed pipelines at relatively high Reynolds numbers.Bothtwo-dimensional and three-dimensional numerical simulation is carried out to determine thethree-dimensional effect.The results of numerical simulation agree quite well with the wave forces actingon pipeline models measured in physical model test.     

宁夏中南部中新世构造活动的地质证据及其意义

通过区域性新生界的对比及不整合面分布的研究,发现宁夏地区中新世曾发生过两次构造运动,一次发生于早中新世,另一次发生于中中新世晚期,但以后者明显,分布也最广。其中前者集中在六盘山以西地区,后者分布在查汗布拉格—三关口—青铜峡—固原(查-固)断裂沿线。宁夏中北部大部分红柳沟组是在受中新世构造运动影响的环境下沉积的。发生于早中新世的构造运动集中体现在六盘山以西的地区和甘肃部分地区,该期运动使渐新统清水营组变形,由于这些现象多发生于海原断裂附近,因此推测在早中新世海原断裂就可能已活动了。而发生于中中新世晚期的运动体现在如下几个方面,在贺兰山中南段西侧发现了中中新世晚期的逆冲推覆活动,堆积了厚度较大的同构造沉积(红柳沟组);在查-固断裂沿线发现了由于中中新世晚期的构造活动而形成的红柳沟组与清水营组之间的角度不整合面,这些说明在该期青藏高原的变形前锋已到达查-固断裂,也就是鄂尔多斯西缘地区,早新生代盆地因此解体;与此同时盆地内部红柳沟组向上逐渐变粗,也说明中中新世晚期较强烈的构造运动已影响到了该区,香山地区开始隆起并分割了早先的盆地,使之成为背驮盆地。宁夏中南部并入到青藏高原东北缘逆冲构造楔之中,该逆冲构造楔中新世向北东扩展的原因可能是由于高原北部在同期显著的隆升运动使得逆冲楔顶角超过临界值,而向前扩展的,查-固断裂是早期类似于目前海原断裂的青藏高原变形前缘,整个高原东北部的扩展并不是前展式,而是一种没有特定顺序的变形。上述这些现象否定了前人认为宁夏地区第三系的变形发生在上新世末期—更新世以后的观点。     

侯光炯院士在紫色土及土壤学研究上的建树

侯光炯院士从事土壤学研究70余年,为我国土壤科学事业的发展作出了巨大贡献.他在紫色土研究上有独到的见解,取得了很多令人注目的成果.尤其是他独树一帜地、创造性地提出了土壤生物-热力学理论,在发展我国独自的土壤学理论研究上有卓越的建树.     

Intelligence-Aided Seismic Zonation System IASHES

In this paper,the structure of the intelligence-aided seismic zonation system IASHES and its validation are briefly introduced.Emphasis is placed on the two rank scheme of potential seismic source areas; an expert subsystem for estimating the seismicity trends of rank A source areas; an expert subsystem for delineation of rank B source areas; an expert subsystem for judgment of upper limit of magnitude of rank B source areas,and an improved procedure for determination of weighting factors of rank B source areas,which is specially suitable to ES(Expert systems).     

鄂尔多斯盆地南部黄土塬区地震资料处理与解释 第二部分:地震资料解释

鄂尔多斯盆地南部的黄土高原,由于长期 风化、侵蚀,形成了树枝状水系与沟、塬、梁、峁、 坡并存的独特黄土地貌。针对这种复杂地表条件长 庆物探已建立了沿沟弯线为主、辅以黄土塬多线和 网状三维的采集方法;确立了高精度静校正、适度 去噪、共反射面元优化及已知井反射系数序列控制 的高保真处理方法、本文着重介绍处理、解释二大 环节的关键方法及应用效果。     

伊犁京希—伊尔曼德金矿床的热液蚀变及成矿流体演化特征

京希－伊尔曼德金矿床的热液蚀变在空间上有明显的分带性，中心蚀变带以强烈的硅化为主，典型的蚀变矿物组合为石英或玉髓和地开石，中间带为高级泥化带，以地开石－高岭石－石英或玉髓为特征；外带为以蒙脱石－高岭石－伊利石－其他粘土矿物等矿物组合为主的泥化带，蚀变强度和矿物组合的分带性是温度、压力和化学梯度的反映，是流体在不断的水或流体－岩石反应和成分交换的产物。该矿床成矿流体演化过程为：早期酸性（pH=2-3)含矿流体在沿断裂上升过程中，受围岩灰岩中的流体（pH为中性）缓冲，在其进入高渗透性的碎屑岩层时，流速和水－岩石或流休－岩石反应大大加快，并在与大气降水的混合作用下，pH值逐步升高（3－5），产生了流体的温度及成分梯度，在温度和压力迅速下降的条件下，金及蚀变矿物沉淀、结晶生长，形成了蚀变空间分带，中心带保存完好的多孔状石英和地开石等高级泥化矿物组合说明该矿床是高硫化热液体系作用下的产物。     

Seawater Corrosion Fatigue of Welded Joints Under Random Variable Amplitude Loading

- Offshore platforms are always subjected to wave action which is random variable amplitude cyclic loading. In order to simulate the stressing condition at the 'hot spot' of the tubular joints and the marine environment, random variable amplitude fatigue tests have been carried out on welded plate joints in sea water. The tests have been conducted under the conditions of loading frequency of 0.2 Hz, stress ratio of -1, seawater temperature of about 20℃ and cathodic protection with the potential about -850 mV, SCE. The test results have been compared with the seawater corrosion fatigue life under constant amplitude loading. Miner's linear cumulative damage summation rule has been used to predict the corrosion fatigue life under variable amplitude loading. The predicted life is in good agreement with the test data.     

The strong ground motion observation for the Wenchuan aftershock

In this paper, the mobile strong ground motion observation for the destructive earthquake is introduced.Considering the characteristics and its spatial distributions of aftershock, 59 strong ground motion instruments were installed along the Longmenshan fault area, and more than 2 000 records have been accumulated.It shows that it is necessary to per-form the mobile strong ground motion observation after the destructive earthquake, and the precious collected data could be applied for further research.     

Evaluation of Earthquake Losses and Establishment of a Corresponding Database System

After the Datong-Yanggao earthquake (October 1989),a special team was organized for the first time by the SSB of China to start the work of earthquake damage evaluation for the purpose of providing the government with a scientific basis for disaster relief.The result of the evaluation played an important role in speeding up rehabilitation and reducing damage losses in the earthquake area.Based on the evaluation of earthquake damage from the Datong-Yanggao earthquake and recent research results,this paper presents a method for quick evaluation of earthquake damages,introduces software entitled EDEP (earthquake damage evaluation program) for evaluating earthquake damage,and cites a case to explain the main function and application of the EDEP.Finally,for a quicker evaluation of earthquake damages,the paper also proposes the establishment of database systems of earthquake damage evaluation in the emphatically monitored areas and ways to build up such database systems.     

近场强地震动模拟中对破裂的方向性效应和上盘效应的表达.

为了模拟近场强地震动，采用了基于有限断层模型的一种随机合成方法．震源破裂面被剖分成一定数量的子源，总的地震矩分成数量更多的子震的矩．一给定子源中一次子震引起的场地地震动的傅氏谱，通过考虑点源的谱、随着距离的衰减、能量耗散及近地表效应等导出．据此幅值谱和一个随机相位谱，并与一个时程包络函数结合，合成一个子震时程．将各子源中各个子震引起的所有时程叠加，得出场地的地震动时程．叠加中，各子震时程之间的时滞，据子震发震时差和子源至场地的距离差别引起的时差确定．对一个设定地震，选用4个断层面倾角，计算了近场21个地点的地震动．结果表明，本文方法可以很好地表达破裂的方向性效应和上盘效应．为了验证方法的可靠性，对1994年美国北岭地震中3个近断层台站MCN，LV3和PCD模拟的地震动与实际记录的加速度反应谱和时程作了比较．