RZB型深井宽频带地形变综合观测系统的垂向应变测量单元

目前钻孔应变观测一般为水平应变,使用无限岩石平板中的钻孔应力集中模型,可反演出水平应力场分布及变化.如果在此基础上加上垂向应力测量,就可反演出三维应力场分布.本文介绍的RZB型深井宽频带地形变综合观测系统的垂向应变测量单元,外钢筒为波纹管结构,并通过螺旋刻丝、热处理等技术,其垂向等效弹性模量比耦合水泥低一个数量级,同时垂向应变钢筒的水平向等效弹性模量高于垂向弹性模量一个数量级.垂向应变探头的力学结构可以被形象地看成是一个螺旋柱形弹簧,其轴向极易产生弹性形变,而水平向的硬度却得到了极大的加强,因此可在竖井中较为准确地测量轴向应变.     

发展钻孔应变观测的战略构想

钻孔应变观测正在成为一种与测震和GPS相提并论的地壳形变观测。曾经处于领先地位的我国钻孔应力一应变观测的发展需要回顾历史,面对现实,借鉴国外,放眼长远。建立比测基地、实验场和完善国家前兆监测网,三位一体,应该成为发展我国钻孔应变观测的基本方针。     

融合多源重力数据的Tikhonov正则化配置法

针对最小二乘配置法在融合处理多源重力数据过程中可能出现的病态性问题,特别引入Tikhonov正则化方法,对配置法计算模型进行正则化改造,建立了相应的正则化配置模型。使用EGM2008位模型模拟产生航空重力和海面船测重力数据进行了融合处理仿真实验,实际验证了正则化处理方法的有效性。     

Landscape pattern evolution processes of alpine wetlands and their driving factors in the Zoige Plateau of China

Zoige Plateau wetlands are located in the northeastern corner of the Qinghai-Tibet Plateau.The landscape pattern evolution processes in the Zoige Plateau and their driving factors were identified by analyzing the dynamic changes in landscape modification and conversion and their dynamic rates of alpine wetlands over the past four decades.The results showed that the landscape conversion between wetlands and non-wetlands mainly occurred during the period from 1966 to 1986.The marsh wetland area converted from lake and river wetlands was larger because of swamping compared to other wetland landscapes.Meanwhile,the larger area of marsh wetlands was also converted to lake wetlands more than other types of wetlands.The modification processes mainly occurred among natural wetland landscapes in the first three periods.Obvious conversions were observed between wetland and nonwetland landscapes(i.e.,forestland,grassland,and other landscapes) in the Zoige Plateau.These natural wetland landscapes such as river,lake and marsh wetlands showed a net loss over the past four decades,whereas artificial wetland landscapes(i.e.,paddy field and reservoir and pond wetlands) showed a net decrease.The annual dynamic rate of the whole wetland landscape was 0.72%,in which the annual dynamic rate of river wetlands was the highest,followed by lake wetlands,while marsh wetlands had the lowest dynamic rate.The integrated landscape dynamic rate showed a decreasing trend in the first three periods.The changes in wetland landscape patterns were comprehensively controlled by natural factors and human activities,especially human activities play an important role in changing wetland landscape patterns.     

A generalized limit equilibrium method for the solution of active earth pressure on a retaining wall

In this paper, a generalized limit equilibrium method of solving the active earth pressure problem behind a retaining wall is proposed. Differing from other limit equilibrium methods, an arbitrary slip surface shape without any assumptions of pre-defined shapes is needed in the current framework, which is verified to find the most probable failure slip surface. Based on the current computational framework, numerical comparisons with experiment, discrete element method and other methods are carried out. In addition, the influences of the inclination of the wall, the soil cohesion, the angle of the internal friction of the soil, the slope inclination of the backfill soil on the critical pressure coefficient of the soil, the point of application of the resultant earth pressure and the shape of the slip surface are also carefully investigated. The results demonstrate that limit equilibrium solution from predefined slip plane assumption, including Coulomb solution, is a special case of current computational framework. It is well illustrated that the current method is feasible to evaluate the characteristics of earth pressure problem.     

华北地区地震环境噪声特征研究

利用华北流动地震台阵观测的垂直分向连续波形数据, 通过计算功率谱密度和相应的概率密度函数, 对华北地区地震环境噪声特征进行了分析研究. 结果表明, 东部平原和沉积盆地2 Hz以上的高频环境噪声水平与全球新高噪声模型（NHNM）相近, 周期3——18 s的平均噪声水平低于NHNM和新低噪声模型（NLNM）的平均值; 山区及西部高原的高频噪声水平明显低于NHNM, 周期1——18 s的噪声水平大多明显低于NHNM和NLNM的平均值; 不同区域18 s以上周期的噪声水平差异相对较小. 流动地震台阵部分台站的环境噪声存在明显的昼夜变化, 个别台站噪声水平明显高于周边台站, 表明这些台站受人类活动干扰较大. 不同台站的噪声水平分析表明, 将台站布设在摆坑内, 能在一定程度上降低高频和低频段的噪声水平. 台站环境噪声特征的研究结果可为流动地震台阵观测数据质量的定量评估, 观测期间的台站优化调整等提供重要依据.      

Fauna and standing crop of freshwater mussels in Poyang Lake, China

Freshwater mussels are a major component of the zoobenthos and they therefore play an important role in freshwater ecosystems. The community composition and the standing crop of freshwater mussels in Poyang Lake, the largest freshwater lake in China and one of two lakes connected to the Changjiang (Yangtze) River, were investigated from February 2008 to May 2009. Mussels were sampled in hydrologically and geographically distinct sampling areas. A total of 42 species and 13 genera were identified, of which 32 species were endemic to China. Two species, Unio douglasiae and Lamprotula caveata, dominated all sampling areas. The number of genera and species, and the number of species within each genus, differed significantly among sampling areas. Freshwater mussels were very abundant, with an overall density of 0.28 ± 0.22 ind./m2 and biomass of 4.08 ± 3.96 g/m2. Significant variation observed among sampling areas and among genera was probably due to the variety of habitats among the areas sampled and to the adaptability of different freshwater mussels to environments. This study suggests that Poyang Lake and other freshwater lakes in the region are important sites of freshwater mussel biodiversity and conservation.     

11年《海洋测绘》论文综述

针对2011年《海洋测绘》刊载的论文情况,从海洋测绘学科发展角度,通过对各专业论文发表情况的统计分析,对海洋大地测量、水深测量、潮汐观测与水位控制、海洋遥感应用、海图制图、卫星定位与导航等专业的发展现状,进行了归纳总结和简要评述。旨在为广大测绘工作者提供参考。     

五台山新太古代绿岩带中高镁安山岩（HMA）的化学特征

采用高镁安山岩（HMA）新的分类方法,描述了五台地区新太古代绿岩带中HMA的化学特征,并与实验的HMA以及自然界中典型的HMA（日本的Chichijima地区HMA和Setouchi地区HMA）进行了对比,显示该区HMA具有与上述HMA类似的化学特征。初步认为五台新太古代HMA产于洋俯冲带的环境,进而表明板块构造理论的适用时间范围可推演到新太古代。     

Last glacial climate variations on the tropical Leizhou Peninsula,South China

Two cores were recovered from raised peat bogs on the tropical northern Leizhou Peninsula, south China. Multiple sediment variables including organic matter (OM) content, the stable carbon isotope signature of OM, low-frequency magnetic susceptibility and degree of humification, indicate that the regional paleoclimate played an important role in determining the nature of peat that accumulated. Based on comparison with other climate proxies, the bulk peat δ¹³C record was interpreted as an indicator of variation in the East Asian (EA) summer monsoon, and to a lesser extent, the Indian summer monsoon, during the last glacial period between ~49 and 10 cal ka BP. More negative bulk δ¹³C values reflect wetter and warmer conditions, and thus a strong EA summer monsoon. More positive values indicate drier and cooler conditions. A warm and wet period occurred between ~46 and 28 cal ka BP, implying a strengthening of the EA summer monsoon. A climate shift occurred at ~22 cal ka BP and the driest and coldest period appeared between ~19 and 16 cal ka BP, suggesting weakening of the EA summer monsoon. After ~12 cal ka BP, climate shifted towards wetter and warmer conditions again. It has been suggested that variations in orbitally induced solar insolation played a role in the last glacial climate of the study region. Several millennial—scale arid and cold phases characterized by C4 plants, or by more positive δ¹³C values during periods when C3 plants dominated, show agreement with the Greenland GISP2 ice core and the Chinese stalagmite records. Interactions between high northern latitude cold air advection and summer moisture transported across the tropical ocean, and the migration of the mean position of the Intertropical Convergence Zone (ITCZ) would have favored these millennial–scale phases. Additionally, changes in heat transport to the North Atlantic would also have influenced climate in the region.