某铁路隧道涌水量预测与分析     

李建平  ;刘汉雄 《中国煤炭地质》2009,(7):34-36

为进行某铁路隧道的设计与施工,获取相关的水文地质参数,进行了3个钻孔的抽水试验,以获取相关的水文地质参数。运用地下水径流模数法、大气降雨入渗法和地下水动力学法对隧道涌水量进行了计算,计算结果显示：地下径流模数法的计算值偏小,降水入渗法的计算值适中,地下水动力学法的精度较高,但计算的涌水量值较大;三种方法比较,决定结果采用大值,即涌水量正常值取6150m^3/d,最大涌水量值取9770m^3/d。提出了采用双向自流排水,适当布设施工监控设备的工程建议。  相似文献   

Environmental impact assessment on water quality deterioration caused by the decreased Ganges outflow and saline water intrusion in south-western Bangladesh   总被引：3，自引：0，他引：3  

Md. Mokhlesur Rahman  Muhammad Qumrul Hassan  Mohammad Saiful Islam  S. Z. K. M. Shamsad 《Environmental Geology》2000,40(1-2):31-40

 This paper deals with an environmental impact assessment of low water flow in the river Ganges during a dry period at the Khulna and Mongla port areas in south-western Bangladesh. Large-scale surface water withdrawal in India after commissioning the Farakka Barrage causes a drastic fall in the Ganges low-flow condition within the Bangladesh territory during every dry period. The average lowest discharge in the Ganges is 552 m³/s, which is about 73% less than that in the pre-Farakka time. This has caused the deterioration of both surface and groundwater quality of the study area. Salinity is the principal cause of water quality degradation in the area. Present observation shows that the surface water of the area is sulphate-chloride dominated, which signifies high salinity whereas the groundwater is categorized as of medium to high salinity. To maintain the Rupsa River's maximum salinity below 1000 μS/cm the discharge in the Ganges should be ∼1500 m³/s, whereas that at Garai basin is ∼10 m³/s. If this present situation continues it will be a crippling blow to the environment of the area in the long term. An integrated multidisciplinary approach to hydrogeological research is urgently required to salvage the area from further deterioration. Received: 9 August 1999 · Accepted: 8 March 2000  相似文献   

Along-Channel Winds in Howe Sound: Climatological Analysis and Case Studies     

Talaat Bakri  Ford Doherty 《大气与海洋》2017,55(1):12-30

This paper examines along-channel winds within Howe Sound, British Columbia, Canada, that occur from both the interior plateau out toward the coast as outflows and from the coast inland as inflows. First, the relationships between along-channel winds and pressure, temperature, and humidity are explored in Howe Sound–Cheakamus Valley. The pressure gradients between Pam Rocks and Squamish and Pam Rocks and Pemberton have the strongest correlations with outflow strength and that between Pam Rocks and Squamish has the strongest correlation with inflow strength. Outflows (inflows) have lower (higher) temperatures and dew point temperatures, except for the inflows in summer, which have lower dewpoint temperatures than the overall mean. Second, two case studies of outflow events are presented and described during the period of intensive observations prior to and during the Vancouver 2010 Winter Olympics. The January 2010 outflow event is caused by a zone of strong across-barrier mean sea level pressure gradient. The pressure gradient is formed behind an Arctic front that moved southward across Howe Sound. The February 2010 outflow event is caused by an approaching sea level low pressure centre from the Pacific that formed a northeast–southwest mean sea level pressure gradient across southern British Columbia. In the January case, the outflow layer is about 1.5?km deep, while it is shallower in the February case. Only the January outflow case exhibits hydraulic behaviour.  相似文献   

Outflow of Pacific water from the Chukchi Sea to the Arctic Ocean     

Robert S Pickart  Greg Stossmeister 《极地研究(英文版)》2008,19(2):135-148

Pacific water exits the Chukchi Sea shelf through Barrow Canyon in the east and Herald Canyon in the west, forming an eastward-directed shelfbreak boundary current that flows into the Beaufort Sea. Here we summarize the transformation that the Pacific water undergoes in the two canyons, and describe the characteristics and variability of the resulting shelfbreak jet, using recently collected summertime hydrographic data and a year-long mooting data set. In both canyons the northward-flowing Pacific winter water switches from the western to the eastern flank of the canyon, interacting with the northward-flowing summer water. In Barrow canyon the vorticity structure of the current is altered, while in Herald canyon a new water mass mode is created. In both instances hydraulic effects are believed to be partly responsible for the observed changes. The shelfl）reak jet that forms from the canyon outflows has distinct seasonal configurations, from a bottom-intensified flow carrying cold, dense Pacific water in spring, to a surface-intensified current advecting warm, buoyant water in summer. The current also varies significantly on short timescales, from less than a day to a week. In fall and winter much of this mesoscale variability is driven by storm events, whose easterly winds reverse the current and cause upwelling. Different types of eddies are spawned from the current, which are characterized here using hydrographic and satellite data.  相似文献   

Tidal modification and its effect on sluice-gate outflow after completion of the Saemangeum dike,South Korea     

Seok Lee  Heung-Jae Lie  Kyu-Min Song  Cheol-Ho Cho  Eun-Pyo Lim 《Journal of Oceanography》2008,64(5):763-776

This study examined tidal modification and change in tidal currents caused by the construction of the Saemangeum dike, based on field observations and a numerical model. The Saemangeum dike was completed in April 2006, enclosing an estuarine area along the mid-western coast of South Korea. After closure of the dike, the tidal range outside the dike decreased slightly but significantly, while the inside tidal range decreased drastically. The numerical model results show that the dike construction has influenced tidal energy propagation and the tidal system in the Yellow Sea. The tidal current speed near the dike decreased abruptly following closure of the dike, except in front of the sluice gates. Since completion of the dike, outflow water discharged from the sluice gates has longer residence times due to the weakened tidal current; the change in the tidal current field has also caused greater northward expansion of outflow water. The sluice gates release fresher water, which spreads over the sea surface mainly by inertial momentum near the gate; this water is then gradually mixed with sea water farther from the gate. The less saline, possibly more contaminated outflow impacts the marine environment near the Saemangeum dike. Controlling the discharge and gate-opening timing can partially mitigate these impacts on the marine environment.  相似文献   

DESIGN OF SLIT DAMS FOR CONTROLLING STONY DEBRIS FLOWS   总被引：3，自引：0，他引：3  

Hui-Pang LIEN 《国际泥沙研究》2003,18(1)

1 INTRODUCTION Stony debris flows are natural, highly concentrated water-sediment mixture, which forms wherever the simultaneous availability of water, debris material and an adequate slope, steeper than o10 are satisfied (Gregoretti, 2000). In mountainous regions of Taiwan, due to vast development and utilization of hills, stony debris flows are important from the point of disaster prevention, since they occur frequently and often bring about heavy loss of lives and properties. Therefo…  相似文献   

深埋特长雪峰山公路隧道工程地质勘察技术研究     

王跃飞  李军  黄辉  胡惠华  丁国华  吴建宁 《中国地质灾害与防治学报》2008,19(4):96-100

雪峰山隧道为深埋特长隧道。在该隧道的勘察过程中运用了大量高新技术,并开展了科研工作,对隧道围岩特性、地质构造、地应力场及岩爆、涌水量、围岩稳定性等与隧道设计、施工密切相关的问题均作出了准确的判断和预测。本文论述了一些新的勘察技术及科研成果,这些勘探与评价技术对其它深埋特长隧道有较好的借鉴作用。  相似文献   

Double-Pulse Laser-Driven Jets on OMEGA     

S. Sublett  J. P. Knauer  I. V. Igumenshchev  A. Frank  D. D. Meyerhofer 《Astrophysics and Space Science》2007,307(1-3):47-50

A double-pulse laser drive is used to create episodic supersonic plasma jets that propagate into a low density ambient medium. These are among the first laser experiments to generate pulsed outflow. The temporal laser-intensity profile consists of two 1-ns square pulses separated by 9.6 ns. The laser is focused on a truncated conical plug made of medium Z material inserted into a high-Z washer. Unloading material from the plug is collimated within the cylindrical washer hole, then propagates into the low-Z foam medium. The resulting jet is denser than the ambient medium. Double-pulse jet evolution is compared to that driven by a single laser pulse. The total drive energy is the same for both jets, as if a source with fixed energy generated a jet from either one or two bursts. Radiographs taken at 100 ns show that a single-pulse jet was broader than the double-pulse jet, as predicted by hydrodynamic simulations. Since the initial shock creating the jet is stronger when all the energy arrives in a single pulse, the jet material impacts the ambient medium with higher initial velocity. Detailed comparisons between single- and double-pulsed jet rheology and shock structure are presented. 2-D hydrodynamic simulations are compared to the experimental radiographs. PACS: 52.30.−q 41.75.Jv 42.62.−b 42.68.Sq 47.40.−x 47.56.+r  相似文献   

An accretion disk,a bipolar outflow,and an envelope—A structure that accompanies the formation of a protostar     

L. I. Matveyenko  V. A. Demichev  S. S. Sivakon’  Ph. D. Diamond  D. A. Graham 《Astronomy Letters》2005,31(12):816-823

We analyze the superfine structure of the supermaser H₂O emission region in Orion KL over the period 1979–1999. The angular resolution reached 0.1 mas, which corresponds to 0.045 AU at a distance to Orion KL of 450 pc. We determined the velocity of the local standard of rest, V_LSR = 7.65 km s^?1. The formation of a protostar is accompanied by a structure that consists of an accretion disk, a bipolar outflow, and a surrounding envelope. The disk is at the stage of separation into protoplanetary rings. The disk plane is warped like the brim of a hat. The disk is 27 AU in diameter and ～0.3 AU in thickness. The rings contain ice granules. Radiation and stellar wind sublimate and blow away the water molecules to form halos around the rings, maser rings. The radiation from the rings is concentrated in the azimuthal plane, and its directivity reaches 10^?3. The relative velocities of the rings located in the central part of the disk 15 AU in diameter correspond to rigid-body rotation, V_rot = ΩR. The rotation period is T ≈ 170 yr. The injector is surrounded by a toroidal structure 1.2 AU in diameter. The diameter of the injected flow does not exceed 0.05 AU. A highly collimated bipolar outflow with a diameter of ～0.1 AU is observed at a distance as large as 3 AU. Precession of the injector axis with a period of ～10 yr forms a spiral flow structure. The flow velocity is ～10 km s^?1. The kinetic energy of the accreting matter and the disk is assumed to be transferred to the bipolar outflow, causing the rotation velocity distribution of the rings to deviate from the Keplerian velocity. The surrounding envelope amplifies the emission from the structure at a velocity of 7.65 km s^?1 in a band of ～0.5 km s^?1 by more than two orders of magnitude, which determines the supermaser emission.  相似文献   

红外源IRAS 05437-0001和IRAS 05351+3549的CO分子谱线观测研究     

江治波  王敏  杨戟 《天文学报》2000,41(1):28-35

利用紫金山天文台青海观测站13.7米射电望远镜对红外源IRAS05437-0001和IRAS05351+3549附近区域进行了CO(J=1-0)的分子谱线观测.发现在这两个源的方向都有很强的CO发射,CO谱线还有明显的线翼成分,这暗示两个红外源存在分子外流.同时还获得了每个源5＇×5＇的成图.通过对高速气体的空间分布的观测和分析,认为这两个源为分子外流源.其中IRAS05437-0001附近区域的外流结构比较复杂,可能这一区域的外流是多极的.IRAS05351+3549附近的外流结构较简单.从两个源的红外光谱分类以及外流的动力学时标得出都是年轻星(年龄～105yrs).通过对这两个外流源的参数估算,得出两个外流源的质量损失率.  相似文献