潮汐汊道形态动力过程研究综述

潮汐汊道是潮流作用占优势的沉积环境之一。潮汐汊道系统的口门水道往往是天然航道,在海港建设上具有重要性。从动力地貌学的观点来看,口门水道形态特征和演化研究涉及多种关键的海岸动力过程,因而具有重要的理论意义。均衡态下的潮汐汊道的口门过水断面面积与纳潮量之间存在着幂函数关系,当用传统的O′Brien方法来确定幂函数曲线时,指数n的值变化范围较大,这是由于参与统计分析的部分汊道系统未达到均衡态而造成的;而应用沉积动力学方法,所获的n值稳定在1.15左右,能更好地代表均衡态断面面积。在断面形状上,小型潮汐汊道可以形成宽浅水道中镶嵌次级水道的形态,以适应沉积物输运和堆积过程,提高汊道系统的稳定性。因此,小型潮汐汊道具有不同于大型潮汐汊道的时间—流速不对称特征。这些研究结果在小型汊道的开发和整治工程上具有应用价值。由于口门断面形态是与口门水道和潮流三角洲的整体特征及其动态相联系的,因此,今后的研究重点应是水动力条件、沉积物输运和堆积过程、水道形态之间的反馈关系,以及与纳潮海湾充填同步的潮流三角洲的生长过程,从而使水道地貌演化能够被定量地模拟。     

地震动力学:震源分布与岩石圈流变特性(英文)

地震震源分布强烈依赖于构造环境的温度和压力条件。震源机制可使大陆地壳脆性-韧性转换带(下部稳定性过渡边界)的温压条件复杂化。该过渡边界伴随速度弱化作用(有震活动)向速度强化作用(无震活动)的转化。在岩石圈流变和壳幔动力学的基础上研究了与板块边界有关的地震活动,包括板缘地震和俯冲板片地震。俯冲带板缘地震的深度分布受约于脆性摩擦动力机制,而摩擦剪切机制不能满意地解释深震活动,包括俯冲板片地震。这是因为深震震源机制可能与高压、高温条件下的固一固相变有关,而用脆性破裂或摩擦作用来解释就不近合理。以理论与实验研究为依据,本文对与震源物理和震源分布有关的岩石圈流变特性进行了较为深入的论述。     

Study of thermal migration and induced mechanical effects in double U-tube energy piles

This paper investigates two geothermal energy piles using thermal response tests (TRTs). A set of parameters including pile wall temperature, ground temperature and strain are monitored at four different depths. The thermally induced mechanical behavior of the energy piles are then analyzed based on the monitoring data.The results show the following: (1) The temperature at the pile wall clearly varies throughout the heating and cooling cycle, and the ground temperature distribution shows a delay compared to the TRT stages. (2) The thermally induced mechanical effects are influenced by both the temperature and restraint conditions.     

流动电势和电渗压力的连续测量实验研究及低矿化度下Onsager互易性的验证

连续测量岩心的流动电势效应和电渗效应,可以获得岩心的动电渗透率,并验证Onsager互易性.通常这两个实验的岩心夹持器需要使用不同的堵头,而更换堵头会导致岩心内流体的参数和边界条件发生变化.本文设计了新的岩心夹持器和激励压力源,避免了在测量过程中更换堵头,提高了两个实验的一致性.本文测量了蒸馏水、以及0.01、0.02、0.05、0.1、0.2、0.4和0.6 mol/L氯化钠溶液饱和的10块岩心的流动电势效应和电渗效应,获得了动电渗透率,并验证了低矿化度下的Onsager互易性.结果表明,Onsager互易性在低矿化度下是成立的;对于高矿化度,电渗效应能够取代流动电势效应用于反演渗透率.

     

THERMAL RESPONSE CHARACTERISTICS OF STONE: IMPLICATIONS FOR WEATHERING OF SOILED SURFACES IN URBAN ENVIRONMENTS

Soiling of stone surfaces by particulate deposition increases absorption of radiant energy, raises surface/subsurface temperature gradients and accentuates rates of surface temperature change. Short-term fluctuation of raised surface temperatures, in response to variations in windspeed and cloud cover, may ultimately contribute to stone breakdown through ‘fatigue’ effects which reduce cohesive strength of intergranular bonds and initiate microfracture development. The effects of soiling are particularly marked for stone with low thermal conductivity and high albedo when clean. Albedo change has implications for the effectiveness of weathering processes and the durability of building stone by creating microenvironmental conditions which are more severe than those indicated by macroenvironmental regimes.     

利用主动震源检测汶川地震余震引起的浅层波速变化

为了监测汶川地震后断裂带附近的波速变化,2008年6月,我们利用快速响应探测系统,在龙门山断裂带北端进行了为期3周的连续观测实验.实验使用电动落锤作为主动震源,GPS连续同步授时的高精度数采作为接收系统.利用记录到的高时间精度观测数据,结合互相关时延检测技术,计算了P波和面波走时的相对变化,来表征地下波速的变化.我们观测到两次面波波速的异常变化,变化幅度最高达到2%,远远大于气压变化所能引起的波速变化.结合该时段内地震活动记录,我们认为面波的波速变化是由在附近发生的两次地震事件的同震效应引起的,该观测结果同理论计算结果相符.     

震情泄露的社会效应对策及其反思

地震震情是社会公众敏感的问题。1991年1月中旬,江苏盐城、镇江、无锡等地因震情泄露而引起强烈的社会反响。本文以镇江为例,概述了以电话潮、抢购热、防震风、保险热、谣言惑众、异常骤增为表现形式的社会效应;介绍了地方政府发挥领导指挥机能,采取富有成效的应急对策,市县地震办公室发挥政府职能作用,积极配合,迅速平息地震风波,取得显著成效;最后从行为评估、得失评估、预测预报、震情保密、社会宣传诸方面进行反思,总结经验教训,以便进一步发挥政府减灾职能作用,做好地震工作。     

冕宁县地震经济损失预测及社会经济影响分析

本文根据冕宁县的社会经济调查资料和建筑物群体震害预测结果,对未来地震引起的经济损失进行了预测,并对地震后可能引起的社会经济影响作了初步分析。     

Response analysis of a submarine cable under fault movement

Based on the performance of submarine cables in past earthquakes, an analytical method to determine cable performance under seabed fault movement is proposed in this paper. First, common types of earthquake damage to submarine cables are summarized, which include seabed displacement induced by fault movement, submarine landslides and seabed soil liquefaction, etc. The damage is similar to damage observed to buried pipelines following land earthquakes. The Hengchun earthquake of Dec. 26, 2006 is used as a case study. The M7.2 earthquake occurred in the South China Sea at 20:26 Beijing Time, and caused 14 international submarine cables to sever and break. The results show that the proposed method predicts damage similar to that observed in the Hengchun earthquake. Based on parametric studies of the influence of the water depth and the magnitude of the submarine earthquake, countermeasures to prevent damage to submarine cables are proposed.