Groundwater resources in the Jabal Al Hass region,northwest Syria: an assessment of past use and future potential

In many cases, the development of groundwater resources to boost agricultural production in dry areas has led to a continuous decline in groundwater levels; this has called into question the sustainability of such exploitation. In developing countries, limited budgets and scarce hydrological data often do not allow groundwater resources to be assessed through groundwater modeling. A case study is presented of a low-cost water-balance approach to groundwater resource assessments in a 1,550 km² semi-arid region in northwestern Syria. The past development of irrigated agriculture and its effect on the groundwater system were studied by analysis of Landsat images and long-term groundwater level changes, respectively. All components of the groundwater balance were determined. Groundwater recharge was estimated using the chloride mass balance method. Over the past three decades, groundwater levels have declined, on average, 23 m, coinciding with a two-fold increase in the groundwater-irrigated area. Groundwater resources are currently depleted by a value that lies between 9.5×10⁶ and 118×10⁶ m³ year^?1, which is larger than can be compensated for by a future decrease in natural discharge or changes in boundary conditions. However, groundwater resources are likely to be sufficient to supply domestic and livestock needs in the area.     

High heat flow anomalies on an old oceanic plate observed seaward of the Japan Trench

Thirty-three new measurements on the seaward slope and outer rise of the Japan Trench along a parallel of 38°45′N revealed the existence of high heat flow anomalies on the subducting Pacific plate, where the seafloor age is about 135 m.y.. The most prominent anomaly with the highest value of 114 mW/m² is associated with a small mound on the outer rise, which was reported to be a kind of mud volcano. On the seaward slope of the trench, heat flow is variable: high (70–90 mW/m²) at some locations and normal for the seafloor age (about 50 mW/m²) at others. The spatial variation of heat flow may be related to development of normal faults and horst/graben structures due to bending of the Pacific plate before subduction, with fluid flow along the fault zones enhancing the vertical heat transfer. Possible heat sources of the high heat flow anomalies are intra-plate volcanism in the last several million years like that discovered recently on the Pacific plate east of the Japan Trench.     

Mechanism for the rapid motion of the Qianjiangping landslide during reactivation by the first impoundment of the Three Gorges Dam reservoir, China

The first impoundment of the Three Gorges Dam reservoir in China started from a water surface elevation of 95 m on June 1, 2003 and reached 135 m on June 15, 2003. Shortly after the water level reached 135 m, many slopes began to deform and some landslides occurred. The Qianjiangping landslide is the largest one; it occurred on the early morning of July 14, 2003 and caused great loss of lives and property. Field investigation revealed that, although failure occurred after the reservoir reached 135 m, the stability of the slope was already reduced by preexisting sheared bedding planes. To study the mechanism of the rapid motion of this reactivated landslide, two soil samples were taken from a yellow clay layer and a black silt layer in the sliding zone, respectively, and a series of ring shear tests were conducted on the samples. One series of ring shear tests simulates the creep deformation behavior, while the other series simulates different shear rates. Conclusions drawn from analysis of the ring shear tests indicate that the mechanism of the rapid motion of the reactivated landslide was caused by the rate effect of the black silt layer during the motion phase after the creep failure. The yellow clay layer did not play any important role in the rapid motion in the 2003 event.     

鄂尔多斯盆地黄陵、东胜地区地温场对比

鄂尔多斯盆地黄陵、东胜铀矿区分别处于盆地南部渭北隆起的北侧边缘和盆地北部伊盟隆起的东部,赋矿层位都是中侏罗统直罗组。盆地南、北铀矿区在现今地温场及古地温场都存在明显差异,南部现今大地热值及热演化程度明显高于北部。对于下侏罗统延安组和石炭—二叠系煤层,黄陵地区镜质体反射率都高于东胜地区。通过镜质体反射率资料得出同一埋深的一套地层经历的最大古地温和对应的古地温梯度也有南部高于北部的现象。由于早白垩世后期盆地普遍整体抬升使得现今地温相对古地温降低,南部黄陵地区抬升剥蚀量大于北部东胜地区,导致古、今地温差异也大于后者。盆地南部庆阳—富县一带局部构造热运动,导致南部异常地温场的形成,使得南部热演化程度高于北部。     

黑龙江省鸡西盆地南、北两带城子河组精细对比

鸡西盆地被平麻断裂分割成南、北两个条带,多数研究者将南带1煤之下的海相层叠伏于北带海相层或底砾岩之下,称为“城子河组下段”或“石河北组”。利用事件地层学的原理,分析盆地内城子河组早期盆地裂陷、海侵、火山喷发、聚煤等重大事件在地层精细对比方面的意义,甄别出了盆地中重大事件的地层记录．以等时层为基础建立对比框架。通过大量钻井资料追溯对比,认为盆地中坳陷部位的渴湖海湾沉积是南北两带的沉积过渡类型,根据微体古生物研究,南北两带海相层中的沟鞭藻类化石面貌基本一致,南北带的海相层应是同一层位,初步实现了盆地内南、北两个条带城子河组的精细对比,为恢复盆地古地理环境奠定了可靠的基础。     

钢筋混凝土圆环内支撑在软土深基坑支护中的设计与应用

通过对星河世纪城B2地块工程基坑成功支护设计实例介绍,全面阐述了钢筋混凝土圆环内支撑体系独特的布置形式、内力计算模式、方法和结果,以及在施工过程中的质量保证,为软土地基中类似基坑工程提供借鉴。     

Inversely-Mapped Analytical Solutions for Flow Patterns around and within Inclined Elliptic Inclusions in Fluid-Saturated Rocks

In this paper, an inverse mapping is used to transform the previously-derived analytical solutions from a local elliptical coordinate system into a conventional Cartesian coordinate system. This enables a complete set of exact analytical solutions to be derived rigorously for the pore-fluid velocity, stream function, and excess pore-fluid pressure around and within buried inclined elliptic inclusions in pore-fluid-saturated porous rocks. To maximize the application range of the derived analytical solutions, the focal distance of an ellipse is used to represent the size of the ellipse, while the length ratio of the long axis to the short one is used to represent the geometrical shape of the ellipse. Since the present analytical solutions are expressed in a conventional Cartesian coordinate system, it is convenient to investigate, both qualitatively and quantitatively, the distribution patterns of the pore-fluid flow and excess pressure around and within many different families of buried inclined elliptic inclusions. The major advantage in using the present analytical solution is that they can be conveniently computed in a global Cartesian coordinate system, which is widely used in many scientific and engineering computations. As an application example, the present analytical solutions have been used to investigate how the dip angle of an inclined elliptic inclusion affects the distribution patterns of the pore-fluid flow and excess pore-fluid pressure when the permeability ratio of the elliptic inclusion is of finite but nonzero values.     

人工触发闪电电流测量及特征性分析

通过对１９９３年７月２７日的人工触发闪电电流、跨步电压的直接测量结果的分析发现,在正电场下触发的慢型放电过程由连续电流和双极性的电流脉冲过程组成,其放电特性与雷暴的电特性有关。闪电电流最大值为１．２ｋＡ,持续时间为２５ｍｓ,中和电荷量为８．９Ｃ。跨步电压与电流的测量结果相一致,是一种间接测量电流的方法。     

饱和软土压缩曲线的“反常”现象

饱和软土压缩试验时,经常出现压缩曲线“反常”、压缩系数“倒大”的现象。它是土的原始结构发生破坏前后的不同压缩性的客观反映。饱和软土的结构力很微弱,唯质量好的原状土才能见到这种“反常”。应从成孔、取样、测试及资料整理等多个环节保证其工程意义。