东营郑南斜坡带砂砾岩体储层微观特征

东营凹陷郑南斜坡带砂砾岩体是古近纪沙四段沉积时期形成的以砂、砾岩为主的近岸水下扇沉积体。储集层岩石结构成熟度和成分成熟度均较低,多为双模态和复模态结构。首先对影响储集层岩石的主要成岩作用进行了描述,分析了该砂砾岩体储集层的孔隙类型和孔隙结构特征。该类砂砾岩体储集层孔隙类型多样,孔隙结构复杂,以中-低孔隙度、低渗透率储层类型为主。     

基于加卸载响应比理论的降雨型滑坡预警研究

在建立边坡远程实时监测系统并获得变形与降雨量连续监测数据的基础上,运用加卸载响应比理论的基本原理,提出以一用为加卸载周期、将日降雨量及其变化作为边坡的加卸载参数、相应的日平均变形速率及其变化值为加卸载响应参数,建立了基于加卸栽响应比的降雨型滑坡短周期预警模型。以某公路边坡为例,运用加卸载响应比预测模型对边坡的2个监测点进行了加卸载响应比计算,发现2个点的加卸载响应比时序曲线与其稳定性动态演化规律相吻合。研究结果表明,可以运用该模型进行降雨型滑坡短周期预测预警。     

The Ledsjö end moraine—a subaquatic push moraine composed of glaciomarine clay in central Sweden

During the Younger Dryas cold event, the Scandinavian ice sheet readvanced in southwest Sweden and formed the Middle Swedish end-moraine zone (MSEMZ). Recent highway construction near Skara has created an exposure through the prominent ridge at Ledsjö. Through sketching and measurement of structural information, we have documented the internal character of the Ledsjö moraine. The moraine consists predominantly of clay with numerous sand pods and lenses, which show undeformed, brittle deformed, or fluidized structures. Based on geomorphology and structural geology, it is clear the moraine was made during two advances. As ice advanced, proglacial marine clay was subglacially mobilized by the ice and extruded at the ice margin forming a ramp of debris-flow sediment. Contemporaneously, subglacial meltwater transported sand to the margin, where the meltwater became a buoyant plume, and sand was deposited near the ice margin by currents moving away from as well as toward the ice margin. These processes resulted in interbedded sand and clay. Continued advance of the ice margin deformed this package and further pushed the assemblage into a ridge form with gravity sliding of portions of the ridge. Prior to the second advance, sand was deposited on the proximal side of the initial ridge. During readvance, this sand was thrust faulted and intruded by mobilized clay. Up ice of the intruded sands, subglacial, extensional deformation created a complex shear zone of faulted sand and clay. The Ledsjö moraine represents a subaerial example of submarine push moraines like the submerged moraines recently documented in Svalbard.     

西安地铁隧道穿越饱和软黄土地段的地表沉降监测

以西安地铁一号线朝阳门站—康复路站区段饱和软黄土地铁隧道为研究对象,通过施工期现场地表沉降变形监测,分析了在饱和软黄土特殊地层条件下隧道浅埋暗挖法施工引起的该区段地表沉降变形规律以及地表沉降槽分布特征。结果表明:在饱和软黄土隧道开挖时,随着掌子面的推进,隧道顶地表沉降可分为沉降微小阶段、沉降显著发展阶段、沉降缓慢阶段和沉降稳定阶段;单线隧道开挖后的最大地表沉降量为18.89mm,双线隧道开挖后的最大地表沉降量为36.4mm;已开挖隧道对围岩土体的扰动作用使得后开挖隧道的地表沉降发展较大;双线隧道的地表沉降槽宽度接近单线隧道沉降槽宽度的2倍,因此可以将其近似为单线隧道地表沉降槽宽度与双线隧道轴线中点距离之和;单线隧道开挖后地表沉降槽宽度为8.4～9.3m,双线隧道开挖后地表沉降槽宽度为16.2～17.5m;隧道开挖施工的沉降槽宽度参数为0.435～0.467,单线隧道开挖后的地层损失率为0.765%～1.324%,双线隧道开挖后的地层损失率为1.231%～2.200%。     

基于多元统计分析的渔山列岛潮间带软体动物功能群和次级生产力比较

渔山列岛于2008年成为国家级海洋生态保护区,为了解渔山列岛保护区内潮间带软体动物次级生产力的时空变化。于1982年和2010年的3个季节(春、夏、冬)在渔山列岛进行潮间带软体动物调查,采用多元统计分析软体动物时空差异,以Brey经验公式计算分析软体动物次级生产力(P值,P/B值)。结果表明,年际间物种食性结构发生了明显的改变,1982年潮间带软体动物对次级生产力贡献率最大的物种有单齿螺(Monodonta labio)、锈凹螺(Chlorostoma rustica),占软体动物总次级生产力的42.88%,2010年潮间带软体动物对次级生产力贡献率最大的物种有覆瓦小蛇螺(Serpulorbis imbricata)、条纹隔贻贝(Septifer virgatus),占软体动物总次级生产力的75.96%。1982年,年均栖息密度为2758ind/m2,年均生物量为2100.26g/m2,年均次级生产力为240.04g/(m2·a),年均P/B值为0.63a–1;2010年,年均栖息密度为699ind/m2,年均生物量为1101.85g/m2,年均次级生产力为94.82g/(m2·a),年均P/B值为0.55a–1。多因素方差分析表明软体动物次级生产力年际间差异显著(F=5.761,P0.05),季节间和潮位间差异都不显著(F=0.135,P0.05;F=2.076,P0.05),P/B的值较低,表明该海域软体动物世代更替速度较慢,2010年的P/B值(0.55a–1)低于1982年的P/B值(0.63a–1),表明近30年来群落结构受到影响。     

平面不规则基础隔震结构抗扭设计研究

针对平面不规则结构在水平地震作用下的振动特性,通过调整隔震层隔震支座的布置,得到3种不同工况的隔震层刚心与上部结构质心、刚心相对位置关系,分别以楼层位移和层间位移为指标的扭转位移比,作为平面不规则基础隔震结构扭转响应指标,利用弹塑性时程分析方法,通过对3种不同工况的扭转指标对比分析研究,提出适用于平面不规则基础隔震结构的抗扭设计方法。结果表明：对于平面不规则结构,应在保证隔震层扭转位移比小于1.2的基础上,使隔震层的刚心和上部结构的刚心分别位于上部结构质心的两侧,可有效控制上部结构的扭转。     

A note on “Origin of components in Chilean thermal waters” by

Risacher et al. (2011) have presented voluminous data on thermal waters of Chile that is quite appreciable; however, their work still falls short on several counts. The most notable shortcoming of the work is the presentation and treatment of data. The interpretations are based on questionable premises (viz., extent of seawater intrusion) and considerations (viz., using average chemical composition of rock types for geochemical modeling, considering volcanic rocks as the only rock type in contact with the geothermal fluids) and assumptions not always substantiated by facts (with proper references) could have been corroborated. Use of Cl/Br ratio for discrimination purpose is unconvincing, considering the uncertainty in the measurement of low (<1 mg/L) Br concentration.     

Experimental and theoretical methods on determination of stress-dependent natural frequency of marine sedimentary clay

Excited by the vibration sources in dynamic engineering, the natural frequency and damping factor of the saturated marine sedimentary clay are key dynamic parameters that influence the responses under cyclic loads. Experimental and theoretical methods are proposed in this paper to analyze the natural frequency and the stress-dependent nonlinearity. The experimental method shows that the natural frequency of soils with specific stress state subjected to large cyclic shear strain can be estimated from the data of dynamic triaxial tests based on the amplitude–frequency response curve. Trial and error by the criterion from the half-power bandwidth method is used to determine the optimal fitting. The results of a theoretical study on the free vibration of soil layers are then presented to derive the analytic solution of natural frequency. In addition to the two frequency-independent elements (a lumped mass matrix and a stiffness matrix), the system’s equivalent damping coefficient matrix is iteratively determined based upon the forced vibration experimentally. Finally, the impacts of the resonance phenomenon on the dynamic shear modulus and hysteretic loop are discussed.     

Effects of different gap filling methods and land surface energy balance closure on annual net ecosystem exchange in a semiarid area of China

Based on eddy covariance measurements over two kinds of land surfaces(a degraded grassland and a maize cropland)in a semiarid area of China in 2005 and 2008,the effects of different gap filling methods,energy balance closure and friction velocity threshold(u*)on annual net ecosystem exchange(NEE)were analyzed.Six gap filling methods,including mean diurnal variation(MDV),marginal distribution sampling(MDS),and nonlinear regressions method,were investigated by generating secondary datasets with four different artificial gap lengths(ranging in length from single half-hours to 12 consecutive days).The MDS generally showed a good overall performance especially for long gaps,with an annual sum bias error less than 5 g C m-2 yr-1.There was a large positive annual sum bias error for nonlinear regressions,indicating an overestimate on net ecosystem respiration.The offset in the annual sum NEE for four nonlinear regressions was from 8.0 to 30.8 g C m-2 yr-1.As soil water content was a limiting factor in the semiarid area,the nonlinear regressions considering both soil temperature and soil water content as controlling variables had a better performance than others.The performance of MDV was better in daytime than in nighttime,with an annual sum bias error falling between-2.6 and-13.4 g C m-2 yr-1.Overall,the accuracy of the gap filling method was dependent on the type of the land surface,gap length,and the time of day when the data gap occurred.The energy balance ratio for the two ecosystems was nearly 80%.Turbulent intensity had a large impact on energy balance ratio.Low energy balance ratio was observed under low friction velocity during the night.When there was a large fetch distance in a wind direction,a low energy balance ratio was caused by mismatch of the footprints between the available energy and turbulent fluxes.The effect of energy balance correction on CO2 flux was evaluated by assuming the imbalance caused by the underestimation of sensible heat flux and latent heat flux.The results showed an average increase of 10 g C m-2 yr-1 for annual NEE in both ecosystems with an energy balance correction.On the other hand,the u*threshold also have a large impact on annual sum NEE.Net carbon emission increased 37.5 g C m-2 yr-1 as u*threshold increased from 0.1 to 0.2 m s-1,indicating a large impact of imposing u*threshold on net ecosystem carbon exchange.