四川地区一次特大暴雨天气过程分析

利用四川省加密气象站逐时降水资料、FY-2G卫星TBB产品及NCEP/NCAR的1°×1°逐6 h再分析资料,对2020年8月15—18日四川地区的一次特大暴雨天气过程进行诊断分析。结果表明：此次过程具有降水强度大、范围广、持续时间长、夜雨特征明显等特征。高空影响槽东移叠加在低空低涡之上,为强降水过程发生发展提供了有利的环流背景和天气尺度动力抬升条件;西太平洋副热带高压（以下简称“副高”）稳定少动是强降水过程长时间维持的主要原因。孟加拉湾低涡槽前西南暖湿气流与副高外围偏南暖湿气流共同为此次强降水过程提供了充足的水汽。中尺度对流系统强烈发展是造成强降水的主要原因,云图TBB≤-52℃的冷云区和TBB等值线梯度极大值区与强降水落区对应关系较好,可为强降水监测预警工作提供参考。     

Analysis of boundary friction effect on the homogenization process of compacted bentonite/claystone mixture with technological voids upon hydration

Pre-compacted MX80 bentonite/Callovo-Oxfordian (COx) claystone mixture has been proposed to backfill and seal the underground galleries for radioactive waste disposal in France. While emplacing these pre-compacted blocks, technological voids are created between the blocks and the host rock and among the blocks themselves. It is expected that homogenization process will take place over time for the structure constructed with pre-compacted blocks upon hydration. This study investigated the boundary friction effect on such a process. Results showed that after the filling of technological voids, the soil far from the technological voids would swell further, while those near the voids would be compressed under the welling pressure generated by the soil behind, resulting in an increase in homogeneity in terms of dry density distribution. However, this homogenization process would stop after a certain time. Further examination showed that the homogenization process ended when the maximum boundary friction force became equal to or higher than the vector sum of swelling forces in the radial direction. Based on the force equilibrium and the mass conservation, the final dry density distribution was estimated. Comparison between the estimation and the measurement showed a good agreement, indicating the relevance of the identified mechanism related to boundary friction.

     

岩石圈深层扩张与青藏高原隆升——岩石圈深层扩张模式初论

在综述有关青藏高原隆升的各种观点和模式后,依据青藏高原新生代变形和岩石圈组构特征,提出了高原隆升的新的动力学模式——岩石圈深层扩张模式。其基本观点是强调由于印度板块向欧亚板块的强烈俯冲造成岩石圈组构和变形的不均一性及岩石圈中存在的碰撞→收缩(重力不均衡)→伸展(均衡调整)的正向转变和由伸展→收缩的逆向转变的反复交替。据此将青藏高原的造山带划分为三种成因类型:喜马拉雅型、冈底斯型和昆仑型。     

地震灾害的心理科学和行为科学研究

1 地震心理研究的国际动态 (1 资料来源.20世纪在15个国家发生了约20个严重破坏性地震,其中有12个国家的19个地震研究机构研究了地震社会经济影响问题,发表的重要研究著作约130余本,论文约1200余篇,研究报告400余个.据统计,有关地震的心理和行为方面的研究论著约30余本和论文100余篇.(2 地震心理问题研究的作用.     

基于斯通利波及电成像测井数据对火成岩裂缝地层的特征分析

随着石油勘探类型的转变和发展,如何高效且准确地识别地层中的裂缝变得十分重要。本文构建了斯通利波在裂缝地层中传播的理论模型,得到了斯通利波在经过裂缝带时会形成反射斯通利波,以及地层中裂缝的条数越多、斯通利波反射系数越大的理论结果。在此基础上,对辽河盆地火成岩地层的声波测井数据进行了斯通利波波场分离（中值滤波）,得到反射斯通利波,并计算了裂缝地层的反射系数。同时对该地层的电成像测井数据进行了孔隙度分布谱和区间孔隙度分析。研究表明：在裂缝发育的地层,反射斯通利波能量增强,反射系数变大;裂缝发育地层电成像孔隙度分布谱明显变宽,电成像区间孔隙度中大孔隙占比增大,显示次生孔隙（裂缝）发育。     

人工地震测深和天然地震流动观测兼用的轻便数字地震仪系统

本文介绍一种新的轻便数字地震仪ＤＡＳ－１。其设计特点是：双微处理器硬件结构;过采样ＡＤ转换技术的运用;线性相位和最小相位ＦＩＲ数字滤波的运用;大容量ＣＭＯＳ快闪存贮器作数据存储介质;ＧＰＳ授时和内部高精度数字钟相结合的时间服务系统;采集器功耗低于０．６５Ｗ。该仪器有３个信号输入通道,０￣４０Ｈｚ的带宽和１６位字长。它可方便地用于人工地震测深及天然地震流动观测。     

Target selection and accessibility for rendezvous with a Near-Earth asteroid mission

Mission to asteroids and comets has been the hot spot of deep space exploration in the new century. The choice of a suitable target, which involves both scientific value and technical feasibility, becomes a difficult task to accomplish due to limited energy and technology. The aim of this paper is to provide an approach to selecting a target and evaluating accessibility for rendezvous with a Near-Earth Asteroid mission, taking into account scientific value and engineering feasibility. Firstly, according to the orbital characteristics and physical properties of Near-Earth asteroids, we make a summary of some of the most frequent factors influencing the target selection of scientific significance. When selecting the target for a space mission, these factors can be regarded as the scientific motivations. Then in order to avoid the possibility that some high priority targets for science would be discarded due to requiring too high an energy budget by using a classical direct transfer strategy, we calculate the transfer trajectory for rendezvous with candidates by using the planetary swingby technique and the global optimal two-impulse method. Finally, through a comparison between the scientific relevance of each possible target and the corresponding estimate of energy needed for rendezvous missions, the ranking of some candidates is identified.     

A density‐dependent elastoplastic hydro‐mechanical model for unsaturated compacted soils

This paper presents a three‐dimensional elastoplastic constitutive model for predicting the hydraulic and mechanical behaviour of unsaturated soils. It is based on experimental results obtained from a series of controlled‐suction triaxial tests on unsaturated compacted clay with different initial densities. Hydraulic hysteresis in the water‐retention behaviour is modelled as an elastoplastic process, with the elastic part modelled by a series of scanning curves and the elastoplastic part modelled by the main drying and wetting curves. The effect of void ratio on the water‐retention behaviour is studied using data obtained from controlled‐suction wetting–drying cyclic tests on unsaturated compacted clay with different initial densities. The effect of the degree of saturation on the stress–strain‐strength behaviour and the effect of void ratio on the water‐retention behaviour are considered in the model, as is the effect of suction on the hydraulic and mechanical behaviour. The initial density dependency of the compacted soil behaviour is modelled by experimental relationships between the initial density and the corresponding yield stress and, thereby, between the initial density and the normal compression line. The model is generalized to three‐dimensional stress states by assuming that the shapes of the failure and yield surfaces in the deviatoric stress plane are given by the Matsuoka–Nakai criterion. Model predictions of the stress–strain and water‐retention behaviour are compared with those obtained from triaxial tests with different initial densities under isotropic compression, triaxial compression and triaxial extension, with or without variation in suction. The comparisons indicate that the model accurately predicts the hydraulic and mechanical behaviour of unsaturated compacted soils with different initial densities using the same material constant. Copyright © 2006 John Wiley & Sons, Ltd.     

Temporal trends of hydro‐climatic variables and runoff response to climatic variability and vegetation changes in the Yiluo River basin,China

The Yiluo River is the largest tributary for the middle and lower reaches of the Yellow River below Sanmenxia Dam. Changes of the hydrological processes in the Yiluo River basin, influenced by the climatic variability and human activities, can directly affect ecological integrity in the lower reach of the Yellow River. Understanding the impact of the climatic variability and human activities on the hydrological processes in the Yiluo River basin is especially important to maintain the ecosystem integrity and sustain the society development in the lower reach of the Yellow River basin. In this study, the temporal trends of annual precipitation, air temperature, reference evapotranspiration (ET₀) and runoff during 1961–2000 in the Yiluo River basin were explored by the Mann‐Kendall method (M‐K method), Yamamoto method and linear fitted model. The impacts of the climatic variability and vegetation changes on the annual runoff were discussed by the empirical model and simple water balance model and their contribution to change of annual runoff have been estimated. Results indicated that (i) significant upwards trend for air temperature and significant downwards trend both for precipitation and ET₀ were detected by the M‐K method at 95% confidence level. And the consistent trends were obtained by the linear fitted model; (ii) the abrupt change started from 1987 detected by the M‐K method and Yamamoto method, and so the annual runoff during 1961–2000 was divided into two periods: baseline period (1961–1986) and changeable period (1987–2000); and (iii) the vegetation changes were the main cause for change of annual runoff from baseline period to changeable period, and climatic variability contributed a little to the change of annual runoff of the Yiluo River. Copyright © 2009 John Wiley & Sons, Ltd.     

Impact of sea spray on upper ocean temperature during typhoon passage: simulation with a 1-D turbulent model

At the interface between the lower atmosphere and sea surface, sea spray might significantly influence air-sea heat fluxes and subsequently, modulate upper ocean temperature during a typhoon passage. The effects of sea spray were introduced into the parameterization of sea surface roughness in a 1-D turbulent model, to investigate the effects of sea spray on upper ocean temperature in the Kuroshio Extension area, for the cases of two real typhoons from 2006, Yagi and Soulik. Model output was compared with data from the Kuroshio Extension Observatory (KEO), and Reynolds and AMSRE satellite remote sensing sea surface temperatures. The results indicate drag coefficients that include the spray effect are closer to observations than those without, and that sea spray can enhance the heat fluxes (especially latent heat flux) considerably during a typhoon passage. Consequently, the model results with heat fluxes enhanced by sea spray simulate better the cooling process of the SST and upper-layer temperature profiles. Additionally, results from the simulation of the passage of typhoon Soulik (that passed KEO quickly), which included the sea spray effect, were better than for the simulated passage of typhoon Yagi (that crossed KEO slowly). These promising 1-D results could provide insight into the application of sea spray in general circulation models for typhoon studies.