民乐-山丹地震的区域构造变形背景与中短期前兆

利用青藏块体北缘地区2001～2003年GPS水平运动资料和1988—2003年跨断层短水准流动观测资料，借助改进的负位错模型及断层形变应变强度比一时变曲线，研究了与2003年10月25日民乐-山丹Ms6．1，Ms5．8地震孕育有关的区域构造变形背景与中短期前兆异常。分析表明，在昆仑山Ms8．1大震引起的大区域形变调整-短期松弛-开始恢复的背景下，民乐-山丹地震震源位于可能反映应变能积累加速的块体边界压性锁定段之间的剪应力强度增强段北侧；距震中最近的石灰窑口跨断层短水准流动场地在震前3个月呈现显著应变强度比异常，而震前10余天至数月内整个监测区异常个数、震前3个月相对近源区异常集中与局部增强均是对这两次地震的某种预示。     

零偏移距共反射面叠加原理及其在工程地震勘探中的应用

对一种能增强工程地震勘探数据质量的新叠加技术——零偏移距共反射面叠加进行了研究。目前模拟零偏移距剖面常规方法存在需要精确宏速度模型及不能对地下反射界面产生最佳照明的问题,而零偏移距共反射面叠加具有完全数据驱动、与宏速度模型无关、能够产生对地下反射界面最佳照明及提高模拟零偏移距剖面成像质量的优势。针对零偏移距共反射面叠加还未在国内工程地震勘探中进行广泛应用的现状,详细介绍了零偏移距共反射面叠加基本原理及其实现过程,并使用一套人工合成断层模型数据及来自某高速公路段附近一条二维测线的实际工程地震勘探数据进行了测试计算。理论模型试算结果及在工程地震勘探实际资料处理中的应用表明零偏移距共反射面叠加可提高地震数据信噪比,增强地震反射同相轴连续性,改善模拟零偏移距剖面质量,是一种非常有发展前景的工程地震成像方法。     

Probabilistic estimation of inelastic displacement demands in soil–structure interaction systems on cohesive soils

Inelastic displacement ratios (IDRs) of nonlinear soil–structure interaction (SSI) systems located at sites with cohesive soils are investigated in this study. To capture the effects of inelastic cyclic behavior of the supporting soil, the Beam on Nonlinear Winkler Foundation (BNWF) model is used. The superstructure is modeled using an inelastic single-degree-of-freedom (SDOF) system model. Nonlinear SSI systems representing various combinations of unconfined compressive strengths and shear wave velocities are considered in the analysis. A set of strong ground motions recorded at sites with soft to stiff soils is used for considering the record-to-record variability of IDRs. It is observed that IDRs for nonlinear SSI systems are sensitive to the strength and the stiffness properties of both the soil and the structure. For the case of SSI systems on the top of cohesive soils, the compressive strength of the soil has a significant impact on the IDRs, which cannot be captured by considering only the shear wave velocity of the soil. Based on the results of nonlinear time-history analysis, a new equation is proposed for estimating the mean and the dispersion of IDRs of SSI systems depending on the characteristic properties of the supporting soil, dimensions of the foundation, and properties of the superstructure. A probabilistic framework is presented for the performance-based seismic design of SSI systems located at sites with cohesive soils.     

岩石蠕变破裂过程及其响应比变化的实验研究

对花岗岩样品进行逐次加载的蠕变实验,得到了加载过程中的蠕变曲线和蠕变破裂的全过程曲线.对加载过程中的杨氏模量、蠕变量、蠕变速率等参数用加卸载响应比方法进行了分析,认为有二种不同形态的响应曲线.在中低应力的弹性阶段其响应比都近似为1,而在高应力的膨胀阶段其响应比都随应力而增加.对应力不变时的蠕变破裂全过程曲线进行了分解,在蠕变破裂过程中,瞬态、稳态和加速3个阶段的持续时间分别为全部时间的18%,75%和7%;在加速蠕变阶段蠕变速率及其响应比明显增加.这一结果是预测蠕变破裂的明显指标.     

测井资料解释煤成气层方法研究

本文在应用计算机对测井曲线进行分层的基础上,利用孔隙差异法、声波差值法、空间模量差比法和电阻率比值法逐层综合解释煤成气层,并对这几种方法在解释煤成气层时可能出现的问题进行了探讨．     

太湖全新世沉积物的古盐度指标及其环境意义

沉积物中的Ｃａ／（Ｆｅ＋Ｃａ）比值和硼含量随水体含盐度的高低而相应增减，它们都是较好的古盐度指标。本文对太湖全新世的沉积物进行了古盐度指标的分析。并与现代湖泊和海洋沉积物作了对比，结果反映东太湖为陆相沉积环境，而西太湖则主要为海相沉积环境。此结论与古生物化石的结论一致，从而证明了太湖地区于全新世期间经历了大规模的海侵，并形成海湾－湖环境。同时也证明了这些古盐度指标是行之有效的。     

北京北部上侏罗统辫状河体系沉积特征

根据野外露头的沉积构造和沉积层序特征,对北京北部延庆硅化木国家地质公园上侏罗统后城组进行沉积相研究,认为该地区以辫状河沉积为主,构成辫状河体系的4种沉积微相类型包括河道、心滩、河间湖泊和溢岸沉积,其中的溢岸沉积相当于曲流河中发育的决口河道与决口扇沉积。运用基准面旋回变化原理,识别出了2个中期旋回和构成中期旋回的多个短期旋回。总结了基准面旋回特征,阐明了地层叠加样式随A/S(可容纳空间/沉积物供给)比值的变化规律,认为低A/S比值时,河道砂体的连通性较好,而高A/S比值时,河道较孤立,连通性较差;且溢岸沉积的地层厚度随着A/S比值的增加不断增大,溢岸沉积的厚度可以作为判断可容纳空间大小的一个依据。     

Organic carbon fluxes from the upper Yangtze basin: an example of the Longchuanjiang River,China

To investigate the effects of anthropogenic activity, namely, land use change and reservoir construction, on particulate organic carbon (POC) transport, we collected monthly water samples during September 2007 to August 2009 from the Longchuanjiang River to understand seasonal variations in the concentrations of organic carbon species and their sources and the yield of organic and inorganic carbon from the catchment in the Upper Yangtze basin. The contents of riverine POC, total organic carbon and total suspended sediment (TSS) changed synchronously with water discharge, whereas the contents of dissolved organic carbon had a small variation. The POC concentration in the suspended sediment decreased non‐linearly with increasing TSS concentration. Higher molar C/N ratio of particulate organic matter (average 77) revealed that POC was dominated by terrestrially derived organic matter in the high flows and urban wastewaters in the low flows. The TSS transported by this river was 2.7 × 10⁵ t/yr in 2008. The specific fluxes of total organic carbon and dissolved inorganic carbon (DIC) were 5.6 and 6 t/km²/yr, respectively, with more than 90% in the high flow period. A high carbon yield in the catchment of the upper Yangtze was due to human‐induced land use alterations and urban wastes. Consistent with most rivers in the monsoon climate regions, the dissolved organic carbon–POC ratio of the export flux was low (0.41). Twenty‐two percent (0.9 t/km²/yr) of POC out of 4 t/km²/yr was from autochthonous production and 78% (3.1 t/km²/yr) from allochthonous production. The annual sediment load and hence the organic carbon flux have been affected by environmental alterations of physical, chemical and hydrological conditions in the past 50 years, demonstrating the impacts of human disturbances on the global and local carbon cycling. Finally, we addressed that organic carbon flux should be reassessed using adequate samples (i.e. at least two times in low‐flow month, four times in high‐flow month and one time per day during the flood period), daily water discharge and sediment loads and appropriate estimate method. Copyright © 2011 John Wiley & Sons, Ltd.     

陇东Q3结构性黄土压剪损伤本构模型试验研究

Q3黄土在我国西北地区分布广泛,且大部分都具有显著的结构性。随着国家“一带一路”倡议的不断向前推进,作为丝路沿线的西北黄土分布地区将迎来新的建设大潮。黄土的结构变形特性非常复杂,深入研究黄土在压缩、剪切条件下的结构损伤变形特性,并依此构建黄土的本构关系在理论研究及现场工程应用中具有非常重要的意义。通过对黄土进行均等压缩试验及三轴剪切试验,基于损伤力学思想,提出黄土结构在均等压缩条件下的平均正应力损伤比,在剪切条件下的平均正应力损伤比及偏应力损伤比。根据弹性、塑性应变确定塑性势线,进而确定其屈服函数;将确定的黄土结构损伤比引入到屈服函数中,得到一定结构损伤时黄土的屈服函数表达式;验证了选取塑性体应变作为本构模型硬化参量的合理性;根据硬化参量与相关试验参数的联系,推导出结构性黄土在压剪条件下的损伤本构模型。经过实测应力-应变曲线与本构模型推算得到的应力-应变曲线对比可知,所建立的本构模型可以较好地反映黄土在压剪条件下结构损伤演化变形过程,具有较好的工程应用前景。     

陕甘宁盆地泥质岩氧化物的比值及其古气候意义

应用泥质岩的多种氧化物比值,探讨了陕甘宁盆地石炭至侏罗纪的古气候状况及其演变规律,自中石炭世至中三叠世,再由晚三叠世至安定期,泥质岩的各种氧化物比值有着逐渐依次增大或减小的两个互不雷同的旋回,与之相应,以上时期反映在古气候上存在着由潮湿→半潮湿→半干燥的早、晚两个旋回。