Numerical evaluation of seismic response of shallow foundation on loose silt and silty sand

This study includes the results of a set of numerical simulations carried out for sands containing plastic/non-plastic fines, and silts with relative densities of approximately 30?40% under different surcharges on the shallow foundation using FLAC 2D. Each model was subjected to three ground motion events, obtained by scaling the amplitude of the El Centro (1940), Kobe (1995) and Kocaeli (1999) Q12earthquakes. Dynamic behaviour of loose deposits underlying shallow foundations is evaluated through fully coupled nonlinear effective stress dynamic analyses. Effects of nonlinear soil structure interaction (SSI) were also considered by using interface elements. This parametric study evaluates the effects of soil type, structure weight, liquefiable soil layer thickness, event parameters (e.g., moment magnitude of earthquake (M _w ), peak ground acceleration PGA, PGV/PGA ratio and the duration of strong motion (D _5?95) and their interactions on the seismic responses. Investigation on the effects of these parameters and their complex interactions can be a valuable tool to gain new insights for improved seismic design and construction.     

Resolving the Routine Presence of Kyanite,Andalusite and Sillimanite across a Region using Foliation Intersection/Inflection Axes Preserved in Porphyroblasts,Petrographic Observations and Thermobarometry

Constraints from P-T pseudosections (MnNCKFMASH system), foliation intersection/inflection axes preserved in porphyroblasts (FIAs), mineral assemblages and textural relationships for rocks containing all three Al2SiO5 polymorphs indicate a kyanite→ andalusite→ sillimanite sequential formation at different times rather than stable coexistence at the Al2SiO5 triple point. All three Al2SiO5 polymorphs grew in the Chl, Bt, Ms, Grt, St, Pl and Crd bearing Ordovician Clayhole Schist in Balcooma, northeastern Australia separately along a looped P-T-t-D path that swaps from clockwise to anticlockwise in the tectono-metamorphic history of the region. Kyanite grew during crustal thickening in an Early Silurian Orogenic event followed by decompression/heating, andalusite and fibrolitic sillimanite growth during Early Devonian exhumation.     

RESOLUTION OF STRONGLY OVERLAPPING TWO-WAY MULTICOMPONENT DATA BY MEANS OF HEURISTIC EVOLVING LATENT PROJECTIONS

High-performance liquid chromatography with diode array detection(HPLC-DAD)is used tocharacterize mixtures from chlorophyll α degradation experiments.Overlapping chromatographic peaksare resolved by means of the heuristic evolving latent projections(HELP)method.The HELP methodis a self-modelling curve resolution method.No assumptions are made about spectral and/orchromatographic peak shape.In the first step the method establishes the real noise level in the data byuse of the so-called zero-component regions.This information is used to reveal selective chromatographicinformation and the number of chemical species at every retention time in unresolved chromatographicpeaks.Utilising the selective chromatographic regions in combination with the zero-concentrationwindows,unique resolution into concentration profiles and spectra of the pure chemical species isaccomplished.HPLC-DAD data from six chlorophyll a degradation experiments were analysed.Consistent results were obtained even with very similar spectra for six or seven overlapping chemicalcomponents.     

AN ANALYTICAL RAYPATH APPROACH TO THE REFRACTION WAVEFRONT METHOD1

Seismic refraction surveying is still an important tool for determining the geometries and elastic wave propagation velocities of near-surface layers. Many analytical and graphical methods have been developed over the years for refraction interpretation, and these can be classified into two basic groups. The first group visualizes critically refracted rays converging on a common surface position, while the second group, which includes the wavefront methods, makes use of the critical rays emerging from a common point on the refractor. The method described in this paper is an analytical approach to the wavefront methods. The reverse refracted ray received by a geophone is intersected by the forward refracted rays received by subsequent geophones and a common critical refraction point on the refractor is estimated after a series of comparisons. This process is repeated for each geophone to yield the geometry and the velocity of the refractor. Several interpolations are performed to achieve a better accuracy. Palmer's models are used to test the efficiency of the algorithm. The results are presented together with those of other methods applied to the same models.     

A comparative study of the Rare Earth Element (REE) distributions within the Lower Cretaceous dolomites and limestones of Central Tunisia

REE distribution, strontium content and oxygen isotopic composition have been studied in the Lower Cretaceous dolomites and their interbedded and/or parental limestones of Central Tunisia. Dolomites, as indicated by previous sedimentologic, geochemical and isotopic study, are different in origin. Environments of dolomite formation include: evaporitic sabkha, deep phreatic, karst and lacustrine. With the exception of the sabkha environment, dolomitizing fluids presumably have been essentially meteoric. The comparison between REE distributions in dolomites and limestones clearly suggests that the general shapes of the REE patterns are preserved during dolomitization. Nevertheless, the total REE amounts are somewhat lowered in dolomites comparatively to parental limestones. Moreover, within the dolomites, the total REE contents are positively correlated to the Sr and δ¹⁸O contents; thus indicating that the decrease in REE, Sr, and δ¹⁸O contents is related to a decrease in the salinity of dolomitizing fluids. In addition, dolomites associated with emergence surfaces (karst) are the most impoverished in REE. Furthermore, they are relatively enriched in light REE, indicating a more or less important fractionation with the REE distributions. This enrichment has been related to the influence of the inorganic complexes which favours the greatest solubility of the heavy REE in basic solution with respect to the lightest members of the REE group.     

基于模式参数化方案的塔中地区临界起沙阈值分析

利用2009年7月4日~29日塔中野外试验观测数据,基于MARTICORENA和SHAO提出的2种起沙模式参数化方案,初步探讨塔中地区不同沙尘天气临界起沙风速,所得结论如下：（1）非沙尘天气,沙尘撞击颗粒数≤ 10 000;扬沙天气,10 001 ≤沙尘撞击颗粒数≤ 20 000;沙尘暴天气,沙尘撞击颗粒数≥ 20 001。（2）基于MARTICORENA起沙参数化方案,临界起沙风速的平均值为4.88 m·s^-1,基于SHAO起沙参数化方案,临界起沙风速的平均值为6.24 m·s^-1,临界起沙风速在非沙尘天气最大,在沙尘暴天气最小。（3）在观测期间沙尘水平通量为732.9 kg·m^-1,其中非沙尘天气125.2 kg·m^-1,扬沙天气80.9 kg·m^-1,沙尘暴天气526.8 kg·m^-1,SHAO起沙参数化方案适合估算总沙尘水平通量以及非沙尘和扬沙天气的沙尘水平通量,MARTICORENA起沙参数化方案适合估算沙尘暴天气沙尘水平通量。     

2013—2016年新疆地闪活动特征分析

基于新疆2013—2016年地闪定位监测资料,对新疆的地闪活动特征进行分析。结果表明：新疆地闪以负地闪为主,占地闪总数的84.7%。年均正地闪所占比例为15.3%,高于内蒙古高原的9.6%。地闪密度总体值小于0.714次/km2?a,呈现出北疆大于南疆,西部地区大于东部地区,山区大于沙漠戈壁的形式;地闪月和日分布均成单峰型,月分布高发期在6—8月,日变化主要集中在14—20时;地闪强度百分率呈现单峰型分布,且负地闪的分布曲线与总地闪基本一致。正地闪出现频率在强度达到30—40kA时出现峰值,为正地闪次数的16.5%;地闪雷电流强度全年变化幅度较小,均呈现先减小后增大的变化趋势。正地闪的平均雷电流强度达59.7kA,为负地闪的1.8倍;上午的平均雷电流强度皆大于下午。     

Diagenetic and Depositional Impacts on the Reservoir Quality of the Upper Jurassic Arab Formation in the Balal Oilfield,Offshore Iran

The Kimmeridgian‐Tithonian aged Arab Formation, as the main reservoir of the Jurassic succession in the Balal oilfield, located in the offshore region of the Iranian sector of the Persian Gulf, is investigated in this study. The formation is composed of dolomites and limestones with anhydrite interbeds. Based on detailed petrographic studies, six microfacies are recognized, which are classified in four sub‐environments including supratidal, intertidal, lagoonal and the high energy shoal of a homoclinal carbonate ramp. The main diagenetic features of the studied succession include dolomitization, anhydritization, cementation, micritization, fracturing and compaction. Based on stable isotope data, dolomitization of the upper Arab carbonates is related to sabkha settings (i.e. evaporative type). In terms of sequence stratigraphy, three shallowing‐upward sequences are recognized, based on core and wireline log data from four wells of the studied field. Considering depositional and diagenetic effects on the reservoir quality, the studied facies are classified into eight reservoir rock types (RRT) with distinct reservoir qualities. Dolomitization has played a major role in reservoir quality enhancement, whereas anhydritization, carbonate cementation, and compaction have damaged the pore throat network. Distribution of the recognized RRTs in time and space are discussed within the context of a sequence stratigraphic framework.     

塔克拉玛干沙漠腹地LAS和EC观测感热通量对比分析

利用2009年6月20日至7月3日塔克拉玛干沙漠腹地塔中地区地-气相互作用观测试验中的大孔径闪烁仪(LAS)和涡动相关仪(EC)观测资料,对LAS和EC在流动沙漠地区观测的感热通量差异进行了对比分析.结果表明:LAS和EC测得的感热通量变化趋势一致,两者有很好的相关性.总体来看,LAS的感热通量测量值大于EC测得的感热通量值.如果LAS和EC测量的允许差异|△H|≤50 W/m2时,LAS和EC测量结果无显著差异的频率达79%左右.因此,LAS完全适用于流动沙漠地区大尺度的感热通量的观测研究.     

星基多光谱分析的降水估算

<正>对从已广泛应用的全球气候模型到局地降水和洪灾的预报而言,准确估算降水的数量、时间和空间分布是至关重要的。降水作为地球水循环的一个关键组成部分,对于人类的生命财产安全有着重要的影响。从区域到全球尺度,现存的地基降水观测网络是不足的;因此,卫星提供了一种可行和吸引人的选择。很显然,