基于岩相的鄂尔多斯白垩系盆地含水层系统结构的研究

依据岩性岩相研究、孔隙度研究、物探洲井解译等成果,对鄂尔多斯白垩系盆地含水层系统的结构进行了划分与研究.结果袁明:盆地北部沙漠高原区含水层系统为单一结构,表现为强富水与中等富水含水层在垂向上叠置与组合,无区域性连续稳定的隔水层,由下到上构成含水统一体;南部黄土高原区为多层结构,表现为含水层与隔水层上下叠置,垂向水文地质分层明显:盆地南、北含水层的结构类型明显不同.利用孔隙度、渗透系数、单位涌水量3个参数,对含水层的富水性级别进行了划分,盆地中共划分出7个强富水含水层、7个中等富水含水层和2个弱富水舍水层.盆地南、北比较,北部含水层孔隙度大,富水性强,地下水主要富集于盆地北部地区.垂向上比较,盆地北部由上到下,孔隙度由大变小,富水性由强变弱,地下水主要富集于浅层和中层:南部上部罗汉洞组和下部洛河组孔隙度较大,富水性好,中部环河组相对较差.地下水主要富集于罗汉洞组和洛河组.     

Atmospheric Water Vapor Pressure over Land Surfaces: A Generic Algorithm with Data Input Limited to Air Temperature, Precipitation and Geographic Location

Summary A lack of information for surface water vapor pressure (WVP) represents a major impediment to model-assisted ecosystem analysis for understanding plant-environment interactions or for projecting biospheric responses to global climate change. This paper reports on a generic algorithm that captures global variation in monthly WVP. The algorithm solves WVP in terms of reduction from saturation WVP as a negative exponential function of potential evapotranspiration; the reduction rate per unit potential evapotranspiration in turn varies with monthly precipitation and a series of variables that distinguish local climate regimes. Data input to the algorithm is limited to monthly air temperature and precipitation, plus latitude, longitude and elevation. The algorithm is specified through regression fitting to monthly climate normal data from 852 stations around the world. It accounts for 96% of the variance in the WVP data, with a root mean square error of 0.17 kPa, or 12% of the data mean. The algorithm closely reproduces five-year sequential monthly WVP data for each of five selected United States locations representitative of diverse climate regimes: the average error generally falls within ±12% of the data mean, and the absolute error within ±0.2 kPa. Its projections also compare favorably against the WVP output from the General Circulation Models for temperature and precipitation conditions under the scenario of a doubled atmospheric carbon-dioxide concentration: the two fall within ±10% of each other for 75% of a total 264 data cases, or within ±20% for 94% of the cases. These statistics suggest that the spatially-based algorithm is useful for projecting temporal variation in WVP, and for extrapolative applications beyond the fluctuation range of present climate. Received March 4, 1999     

长江三角洲晚第四纪地层沉积特征与生物气成藏条件分析

对长江三角洲晚第四纪地层沉积特征进行了精细研究,探讨了研究区层序地层格架,在此基础上分析了浅层生物气成藏条件、特征和分布规律。研究表明,长江三角洲晚第四纪发育3期下切河谷,形成了3套沉积层序;因后期河流的强烈下切破坏,早期沉积层序往往被剥蚀殆尽,仅残留下部的河床相粗粒沉积,造成不同期河床相的叠置;相对而言,末次冰期以来形成的下切河谷沉积层序以相对完整的沉积相组合被保存下来。长江三角洲浅层天然气是未经运移的原生生物气,其主要富集于末次冰期以来的沉积层序内,气藏为自生自储同生型的岩性圈闭。河口湾—河漫滩和浅海相泥质沉积物既是气源岩,又是盖层,后者可作为良好的区域盖层;河口湾—河漫滩和河床相砂质沉积物为主要储集层。因此,研究区晚第四纪多期下切河谷沉积层序有利于浅层生物气藏的形成,特别是晚期下切河谷内河口湾—河漫滩相砂质透镜体以及河床相砂体可作为优先勘探目标。     

不同顶管组合方式的管幕冻结温度场模型试验

拱北隧道作为港珠澳大桥珠海连接线的关键性工程,在国内外首次成功运用了管幕冻结技术。以此为背景,为更加全面地掌握饱和软土地层中管幕冻结温度场的分布特点,开展了不同顶管组合方式下的管幕冻结温度场模型试验研究。试验结果表明:各测点温度曲线在积极冻结期前4h急剧下降,随后逐渐减缓,降至砂土冰点后趋于平稳,三种布管方式均满足冻结设计要求;冻结管中低温盐水提供的冷量首先传递给顶管管壁,再以面的形式均匀地传递给周围土体;积极冻结21h后,采用四根空顶管组合的C区冻结壁竖向范围最大,空管管壁正上方冻结壁平均厚度约为105mm,在满足管幕刚度设计要求的前提下,可采此布管方式以达到快速形成冻结帷幕的目的。限位管开启后的4h内,实顶管中线垂直距离100mm范围内测点温度曲线虽有明显回升但仍维持在冻土冰点以下,超出此范围后温度变化影响逐渐减弱,且顶管间冻结壁稳定存在,表明限位管在满足管间有效封水的条件下,能在一定范围内起到定向限制地层冻胀的作用。优化后的双圆形冻结管在满足冻结设计要求的同时,更加便于安装且经济环保。     

Frequency-dependent rupture process,stress change,and seismogenic mechanism of the 25 April 2015 Nepal Gorkha <Emphasis Type="Italic">M</Emphasis><Subscript>w</Subscript> 7.8 earthquake

On 25 April 2015, an M _w 7.8 earthquake occurred on the Main Himalaya Thrust fault with a dip angle of ~ 7° about 77 km northwest of Kathmandu, Nepal. This Nepal Gorkha event is the largest one on the Himalayan thrust belt since 1950. Here we use the compressive sensing method in the frequency domain to track the seismic radiation and rupture process of this event using teleseismic P waves recorded by array stations in North America. We also compute the distribution of static shear stress changes on the fault plane from a coseismic slip model. Our results indicate a dominant east-southeastward unilateral rupture process from the epicenter with an average rupture speed of ~3 km s^?1. Coseismic radiation of this earthquake shows clear frequency-dependent features. The lower frequency (0.05–0.3 Hz) radiation mainly originates from large coseismic slip regions with negative coseismic shear stress changes. In comparison, higher frequency (0.3–0.6 Hz) radiation appears to be from the down-dip part around the margin of large slip areas, which has been loaded and presents positive coseismic shear stress changes. We propose an asperity model to interpret this Nepal earthquake sequence and compare the frequency-dependent coseismic radiation with that in subduction zones. Such frequency-dependent radiation indicates the depth-varying frictional properties on the plate interface of the Nepal section in the main Himalaya thrust system, similar to previous findings in oceanic subduction zones. Our findings provide further evidence of the spatial correlation between changes of static stress status on the fault plane and the observed frequency-dependent coseismic radiation during large earthquakes. Our results show that the frequency-dependent coseismic radiation is not only found for megathrust earthquakes in the oceanic subduction environment, but also holds true for thrust events in the continental collision zone.     

甘肃巴谢剖面黄土-古土壤的光释光测年研究

光释光（OSL）测年是测定第四纪沉积物年龄的一种新技术。它通过单色光束激发使晶体中储存的电离辐射能释放出来。与热释光（TL）测年相比，OSL测年可以不考虑残留的OSL信号，而且测量具有简便、迅速且准确等优点。本文用细颗粒光释光技术对甘肃巴谢剖面的黄土-古土壤进行了测定，其测年结果与14C测年结果相吻合。这表明，光释光是一项极潜力的年代学技术。     

基坑支护结构破坏原因综述及实例分析

高层建筑基坑支护结构破坏原因主要有 :支护结构整体失稳、基坑土体隆起、管涌及流沙的出现、支撑强度不足或压屈、墙体破坏、支护结构平面变形超过限度。某大厦施工中由于桩身强度不足、桩尖达到的深度不够及桩间距过大等原因 ,致使管涌发生 ,造成塌方。通过对事故针对性的处理 ,取得了良好的效果     

河北唐山曹妃甸浅滩潮道(纳潮河)开通过程及开通意义

曹妃甸填海工程初期规划有明显缺陷,填海面积过大,尤其是阻断了浅滩潮道(纳潮河),对海洋环境、老龙沟港口潜力区有明显损害。作者的积极建议和相关论文的发表促成了2007年曹妃甸新填海规划的出台,其中保留浅滩潮道(即开通纳潮河)和在老龙沟上游修建大港池是新规划的主要改进内容。阻断浅滩潮道后曹妃甸区域的地形地貌及水动力变化证实了作者观点的正确性。纳潮河于2016年8月开通。纳潮河的开通,可大大提升曹妃甸景观,增加约40 km不淤积的优良海岸线,部分恢复原海洋潮流系统和保护海洋环境,促进海水的循环,并使曹妃甸的几个港池不再淤积或淤积变轻。     

南极普里兹湾海域铀系同位素的分布

本文报道了南极普里兹湾海域U、2 2 6Ra、2 1 0 Pb、2 1 0 Po的分布以及2 34U/2 38U和2 1 0 Po/2 1 0 Pb放射性比值。研究结果表明 ,该海域表层水中的铀同位素分布基本均匀 ,铀含量范围为1 3 2 8- 1 4 2 0 μmol·m- 3,平均值为 ( 1 3.82± 0 .2 9) μmol·m- 3,2 34U/2 38U平均放射性比值为1 1 4± 0 0 3。铀含量与盐度之间存在良好的相关性 ,其相关系数达 0 895。该海域溶解态2 2 6Ra比活度范围为 1 37- 1 78Bq·m- 3,平均值为 1 5 5Bq·m- 3;颗粒态 2 2 6Ra比活度范围为0 0 0 6- 0 0 35Bq·m- 3,平均值为 0 0 1 5Bq·m- 3;2 1 0 Po比活度 0 80- 1 5 2Bq·m- 3,平均 1 1 4Bq·m- 3;2 1 0 Pb比活度 1 34- 2 1 5Bq·m- 3,平均 1 66Bq·m- 3;2 1 0 Po/2 1 0 Pb的放射性比值0 5 5- 0 84,平均 0 69。并对2 1 0 Po和2 1 0 Pb的不平衡作了讨论。还研究了 1个站位溶解态和颗粒态2 2 6Ra、2 1 0 Pb的深度分布及2 1 0 Pb在两相中的分配     

基于岩相的鄂尔多斯白垩系盆地含水层系统的结构研究

依据岩性岩相研究、孔隙度研究、物探测井解译等成果,对鄂尔多斯白垩系盆地含水层系统的结构进行了划分与研究。结果表明：盆地北部沙漠高原区为单一结构,表现为强富水与中等富水含水层在垂向上叠置与组合,无区域性连续稳定的隔水层,由下到上构成含水统一体;南部黄土高原区为多层结构,表现为含水层与隔水层上下叠置,垂向水文地质分层明显;盆地南、北含水层结构的结构类型明显不同。利用孔隙度、渗透系数、单位涌水量3个参数,对含水层的富水性级别进行了划分,盆地中共划分出7个强富水含水层、7个中等富水含水层和2个弱富水含水层。盆地南、北比较,北部含水层孔隙度大,富水性强,地下水主要富集于盆地北部地区。垂向上比较,盆地北部由上到下,孔隙度由大变小,富水性由强变弱,地下水主要富集于浅层和中层;南部上部罗汉洞组和下部洛河组孔隙度较大,富水性好,中部环河组相对较差,地下水主要富集于罗汉洞组和洛河组。