昆仑山口西8.1级地震的崩塌发育特点

昆仑山口西8．1级地震造成20余处崩塌体或崩塌带，主要分布在地震地表破裂带附近，以库赛湖以西为主。崩塌可分为基岩崩塌、土体崩塌、冰体崩塌、雪崩4种类型。本文对崩塌的空间分布和发育特点进行了分析，通过与其它大地震相比，认为本次地震崩塌规模较小，除介质岩性、地形地貌、气候等因素外，地震动不十分强烈是崩塌规模偏小的重要原因。这种地表破裂带长而地震动偏弱的现象，是本次地震破裂的重要特点，可能与先存断裂的结构有关。     

关于"长河二号"导航系统的时间同步及授时

对“长河二号“导航系统的时间同步及快速恢复等问题作了讨论,提出了利用BPL长波信号、GPS共视或搬运钟等方法来实现时间同步和增加授时功能的方案.最后,给出了“长河二号“东海台链的主台信号与国家授时中心的UTC(NTSC)之间的同步实验结果.     

中国海域双壳类软体动物数据库的结构与功能

于１９９１－１９９５年，运用数据库管理系统调用地理信息系统，图象处理信息系统等计算机技术，将我国海域内已查明的１０００余种双壳类动物以数据库的形式进行管理，本数据库管理系统由查询，修改、统计、打印和绘图５个子系统构成，子系统之间以层次控制管理为主。为生物学研究和科学管理实现现代化进行探索。     

Susceptibility assessment of the precursor stage of a landslide threatening Haivan Railway Station,Vietnam

Haivan Station is an important station on the North-South railway line in central Vietnam. Field investigation has identified a precursor stage of a landslide that would threaten this railway. Therefore, a landslide susceptibility assessment for Haivan Station was urgently needed to protect passenger safety and the national railway. Conducted investigations included air-photo interpretation, drilling, ground water and inclinometer monitoring, laboratory testing, and landslide simulation. This research applied the undrained dynamic loading ring shear apparatus ICL-2 to drill-core samples from the precursor landslide. Samples for ring shear tests were taken from sandy soil layers found at depths of ~21, ~31, and ~50 m in the cores. Each of these was believed to be a possible sliding surface of a landslide, and all were tested to shear failure in the ICL-2 apparatus. The boundary between highly weathered granitic rock and weathered granitic rock was identified at about 50 m depth. The inclinometer monitoring detected slight movement at this depth. Therefore, the present day risk of a landslide forming at 50 m is higher than for one forming at either 21 or 31 m. The landslide dynamic parameters obtained from the ring shear test of the 50-m-deep sample were used in an integrated numerical simulation model LS-RAPID. The simulation result gave the critical pore-pressure ratio for landslide occurrence, and landslide’s likely maximum speed, total volume, and depth of landslide debris that could cover the railway. These estimates serve to raise awareness of the vulnerability of the Vietnam national railway sector to landslide impact.     

Report of LA-ICP-MS zircon U-Pb dating (272 Ma) of gabbros in Yagan area,northern Alxa,Inner Mongolia: Insights into the tectonic evolution of the southern Paleo-Asian Ocean

1.Objective The northern margin of the Alxa Block in Inner Mongolia is located in the middle part of the southern margin of the Central Asian Orogenic Belt.It serves as a key position that connects the eastern and western tectonic units of the Central Asian Orogenic Belt and is an ideal site for the research on the final closing process of the Paleo-Asian Ocean.     

基于cole-cole复电阻率模型的线源可控源有限元数值模拟

受激发极化效应的影响,大地中岩(矿)石电阻率是一个与频率、电化学性质等因素有关的复电阻率。接收到的电磁场信号中,包含了电磁感应效应以及激发极化效应双重因素的影响。将cole-cole复电阻率模型引入二维线源可控源正演理论,加载伪delta函数,实现了含激发极化效应的线源可控源有限元数值模拟。计算了不同极化参数的二维地质体线源可控源的影响特征。结果表明:线源可控源响应对IP效应反映明显,视电阻率出现增高的特征;低阻高极化相对于高阻高极化模型受IP效应影响更大,从低阻中提取IP效应更加乐观。该研究为实现从复杂地质条件下CSAMT信号提取IP效应奠定了基础。     

Experiment and Study on Mechanical Property of Sandstone Post-peak Under the Cyclic Loading and Unloading

Engineering research has shown that the surrounding rock of deep roadways experienced many times of post-peak cyclic loading and unloading. So studying on rock mechanical characteristics of post-peak loading and unloading is helpful to control the deep surrounding rocks. The test using RMT-150B rock mechanics testing system, to experiment on the mechanical properties of sandstone of post-peak cyclic loading and unloading. The results show that: the stress–strain curves of post-peak cyclic loading and unloading have significant plastic hysteretic loops. The area of plastic hysteretic loops gloss back. The enveloping outer enclosure of cycle loading curve is the similar as the stress–strain curves of strain softening stage when the samples failure, which shows that post-peak failure of rocks have significant memory. With the increase of cycles, the cumulative deterioration parameters are gradually increased, and the ultimate bearing capacity, elastic of loading section of samples and cumulative deterioration parameters conform with the exponential attenuation function with constant term. With the increase of surrounding pressure, the total energy, dissipated energy and elastic energy of samples are gradually increased. With the increase of cycles, the total energy, dissipated energy and elastic energy of samples all are gradually decreasing, the rate of reduction decreases gradually. The samples exist in vertical splitting and transverse shear combination failure under the post-peak uniaxial cycles, or exist in shear failure under the post-peak triaxial cycles. The shear plane exists slip traces.     

The Stability and Existence Condition of Nonlinear Travelling Wave Solution in Basic Uniform Flow

Summary  Nonlinear waves in a stratified atmosphere with basic uniform flow are studied by adopting geostrophic momentum approximation (cf. Hoskins, 1975) and the method of travelling wave solution. A nonlinear equation containing a unique variable of vertical p velocity is derived from a complete system of equations considering frictionless and adiabatic fluid. The stability of the solution for the nonlinear equation is discussed then. Furthermore, the approximate cnoidal wave solution, solitary wave solution and their existence condition are obtained. Received July 8, 1998 Revised December 1, 1998     

Agrochemical and polychlorobyphenyl (PCB) residues in the Mekong River delta, Vietnam

An environmental survey on pesticide residues and polychlorobyphenyl compounds (PCBs), encompassing more than 70 polar and non-polar compounds quantifiable by the techniques used, was performed in the Mekong River delta based on analyses of water, sediment and bivalve mollusc samples. Few polar compounds, such as diazinon and fenotrothion, were detected in water but a high number of non-polar chlorinated compounds, such as DDT, HCH, endosulfan and PCBs, were detected in sediments and biota. The highest concentrations measured were of DDT with an average 6.3 ng g(-1) dry weight (range 0.32-67 ng g(-1)) in sediments and 38.6 ng g(-1) (range 5.5-123 ng g(-1)) in molluscs' soft tissues. Amongst chlorinated compounds, DDT concentrations were followed in decreasing order by those of PCB, endosulfan, hexachlorocyclohexane and chlordane. Residues of organochlorine compounds originate from local usage of agrochemicals although with a likely contribution also of atmospheric deposition of residues (not measured) originated elsewhere. Concentrations of PCB and pesticide residues in the aquatic environment of the Mekong River delta are lower than values reported for other regions of Vietnam and Asia. Nevertheless, current concerns about the effects of chlorinated compounds on public health advise improved control of chemical residue discharges in order to abate environmental contamination.     

中国沙漠(地)深层渗漏量及动态特征

土壤水分深层渗漏是沙区水循环的重要环节,深层渗漏的定量测定对沙区水资源评估及水量平衡研究具有重要意义。本文采用YWB-01型土壤深层水量渗漏测试记录仪对中国毛乌素沙地等六大沙漠(地)降雨入渗到深层土壤的渗漏水量进行实时动态监测。结果表明:流动沙丘降雨渗漏补给量存在明显的时空差异,与降雨时空变化特征具有相对一致性,降雨格局是影响深层渗漏过程的主要因素,随降雨增大渗漏补给量增加,半干旱区降雨量与渗漏量显著正相关(p<0.05),干旱区相关性不显著(p>0.05);观测期内正镶白旗、伊金霍洛旗、阜康流动沙丘土壤200 cm以下渗漏量为48.5、146.8、1.0 mm,分别占同期降雨的21.4%、33.3%、1.3%;乌审旗、磴口150 cm以下渗漏量为1009.6、52.6mm,分别占同期降雨的55.7%、12.7%。不同气候区固定沙丘渗漏量基本没有差异,降雨格局不是影响水分深层渗漏的主导因素,而植被覆盖的影响占主要作用,且沙丘植被盖度>45%时深层渗漏量不超过同期降雨的2.0%。中国沙区深层土壤水分补给主要来自于强降雨或高频次小降雨事件,特别是干旱区降水少、频次低,其深层土壤水分补给更加依赖于强降水。