Study on numerical simulation to water lowering in an open coal mine digging

In view of the situation of excavation of open coal mine for the underground water disaster,we should carry out simulation studies for the numerical value of the water lowering project and improve the accuracy and the level of the water lowering project.On the basis of the hydrological geological conditions of certain open mine digging,a more reasonable seepage numerical model was built according to MODFLOW.It was simulated in advance that the process of the confined water level descending with the time,and combining with the actual observations to test the correctness of the model.The calculation showed that the results coincided well with the results of actual measurement.Based on this,different water lowering numerical simulations were built for the open coal mine digging.It could be simulated and forecast that the changes of the groundwater level in drainage process within and outside the mine pit,and it was quantitatively assessed that the possible water lowering result of the opencast water drainage process,which provide an important basis for the actual water lowering project and the possible project disposal.     

Wave-Current Forces on Vertical Cylinders in Side-by-Side Arrangement for Irregular Waves Combined With Opposing Current

- The wave-current forces on vertical piles in side-by-side arrangement induced by irregular waves with opposing current are investigated experimentally in this paper. The characteristics in both time and frequency domain of in-line, lift and resultant forces are analyzed. The grouping effect coefficients of inline, lift and resultant forces on piles related to KC number and relative spacing parameters are given. These results are compared with those in the case of irregular waves combined with following currents. It is found that the results in these two cases are quite different. The range of KC number tested is 10- 60, the range of Reynolds number is (0.55-3.43) ×104.     

Wave-Current Forces on Slender Circular Cylinders

- A series model tests of wave forces by both regular and irregular waves combined with currents on single piles and bipiles in tandem and parallel arrays have been carried out. Based on Morison Equation, linear wave theory and linear wave spectrum theory as well, the characteristics of inline, lift and resultant forces on cylinders have been analyzed respectively. The drag, inertia and lift coefficients CD, CM and CL f皉 single piles related to KC number and the grouping effect coefficients of inline, lift and resultant forces on bipiles in tandem and parallel arrays related to KC number are given in this paper.     

Solar-, monsoon- and Kuroshio-influenced thermocline depth and sea surface salinity in the southern Okinawa Trough during the past 17,300 years

Factors influencing millennial-scale variability in the thermocline depth (vertical mixing) and sea surface salinity (SSS) of the southern Okinawa Trough (OT) during the past 17,300 years were investigated based on foraminifer oxygen isotope records of the surface dweller Globigerinoides ruber sensu stricto and the thermocline dweller Pulleniatina obliquiloculata in the AMS ¹⁴C dated OKT-3 core. The thermocline depth is influenced by surface thermal buoyancy (heat) flux, in turn controlled by the annual mean insolation at 30°N and the strength of the East Asian winter monsoon (EAWM). Strong insolation and weak EAWM tend to increase buoyancy gain (decrease buoyancy loss), corresponding to shallow thermocline depths, and vice versa. Regional SSS is influenced by the global ice volume, the Kuroshio Current (KC), and vertical mixing. A deep thermocline coincides with a high SSS because strong vertical mixing brings more, saltier subsurface KC water to the surface, and vice versa. Local SSS (excluding the global ice volume effect) became lower in the northern OT than in the southern OT after ~9.2 ka, implying that Changjiang diluted water had stronger influence in the northern sector. SSS show no major changes during the Bølling/Allerød and Younger Dryas events, probably because the KC disturbed the North Atlantic signals. This argues against earlier interpretations of sea surface temperature records of this core. Wavelet and spectral analyses of the Δδ¹⁸O_P-G (δ¹⁸O of P. obliquiloculata minus G. ruber s.s.) and δ¹⁸O_local records display 1,540-, 1,480-, 1,050-, 860-, 640-, and 630-year periods. These are consistent with published evidence of a pervasive periodicity of 1,500 years in global climate as well as EAWM and KC signatures, and a fundamental solar periodicity of 1,000 years and intermediary derived periodicity of 700 years.     

鸭绿江河口沉积物元素地球化学及其控制因素

对鸭绿江河口地区的56个站位沉积物的常量元素含量进行了测试,并对测试结果进行了多元统计分析。研究结果表明,多数常量元素含量在鸭绿江西岸潮滩地区和西部海域波动较小,而在上游地区和河口口门地区变动较大,在河口最大浑浊带内出现两个峰值。R型主因子分析结果表明,粒度控制效应对鸭绿江河口地区常量元素的含量分布起着主要作用,贡献方差达76.55%。运用Q型聚类分析将各站位归为两种类型,揭示出沉积动力环境的差异是造成这种常量元素地球化学分区特征的最主要因素。此外,通过与附近河口对比发现鸭绿江河口及近岸地区沉积物中的常量元素含量同朝鲜半岛的河流、中朝准地台花岗岩以及朝鲜半岛花岗岩比较接近,但与长江和黄河有着较大的差异。     

论中国古代地缘战略制定中的“权衡”——以《盐铁论》为例

《盐铁论》是记录汉朝时期关于盐铁酒榷均输及对匈奴关系的辩论的一部重要著作,能够较典型地反映中国古代地缘战略制定中的“权衡”过程。构建中国古代地缘战略制定中的“权衡”理论分析框架,继而基于该分析框架对《盐铁论》中的地缘战略辩论进行详细解读。《盐铁论》中辩论双方“权衡”的要点包含匈奴对汉朝产生的威胁程度、领土扩张所带来的收益大小和相应地缘战略的合法性3个方面。从思想、方法、目的等比较中西方地缘政治研究差异,指出“权衡”思想为西方主导的地缘政治理论提供新视角。     

苏北潮滩湿地不同生态带碳、氮、磷分布特征*

通过对比苏北潮滩湿地不同生态带的表层以及柱状沉积物中总有机碳、总氮、总磷和有机磷含量,并结合不同植被不同植株部位中碳、氮、磷的含量变化,分析了潮滩沉积物中碳、氮、磷的垂向和水平分布特征与规律,探讨了不同生态带以及潮滩植被对碳、氮、磷等生源要素的富集作用。对比分析结果表明:苏北潮滩湿地各生态带对不同的测量指标有着不同的富集作用,互花米草滩的总有机碳、总氮和有机磷含量要远大于其他几个生态带,光滩沉积物中总磷的含量最高; 粒度效应是控制互花米草前缘地带以及互花米草滩沉积物中有机碳和氮分布的一个重要因素,盐蒿和芦苇滩中有机碳和氮的分布更多的是受粒度之外的其他因素影响; 不同生态带表层沉积物中的C/N比值分布,大致可反映其有机物来源的差异,而不同生态带中柱状沉积物中的C/N比值相对接近,很难根据C/N比值大小来对不同生态带中的有机物来源进行判断,这可能是埋藏在柱状沉积物中的有机物更多的受到了早期成岩作用造成的。植被对潮滩湿地中碳、氮、磷的分布有着重要影响,3种物质在互花米草、盐蒿和芦苇中的含量差别不是很大,因此潮滩植被对沉积物中上述3种物质的贡献差别主要是由不同植被的生物量和其所处环境的沉积动力差异造成的。     

地震动记录选取及其对网架屋盖动力响应的影响

地震动记录的合理选取对预测结构响应有着重要的作用。本文通过对风雨操场建筑混合结构的抗震性能分析,提出了一种对水平及竖向地震动频谱特性均进行控制的改进选波方法。为了评价不同选波方法的可靠性和有效性,根据初选条件选取55组三向地震动记录,并以55组地震动的统计反应谱作为目标反应谱,以55组记录计算的结构响应均值作为"预测值",通过与单周期点和双频段选波方法的计算结果对比,分析表明:改进选波方法计算的结构基底剪力、柱顶位移、支座位移和网架竖向位移的相对误差和变异系数均小于前两种选波方法,其计算结果更加可靠有效。     

青海木里冻土区天然气水合物钻探施工技术

钻探取心是天然气水合物资源调查研究的一种重要技术手段,也是识别天然气水合物最有效的方法之一。青海木里煤田三露天调查区地质构造复杂,水合物钻探施工时极易出现孔壁坍塌、水合物分解、气侵泥浆及孔内涌气、涌水、漏失等问题,取芯困难、钻进效率低。针对这些技术难题,开展了泥浆制冷技术、大口径绳索快速取心钻进技术、聚合物低温泥浆工艺及泥浆防塌体系、钻孔结构及钻进参数优化、钻头选型、气体防喷等技术工艺研究,并在现场实践中取得了较好的效果,为今后青藏高原冻土地带进行天然气水合物钻探施工提供借鉴。     

华北中部岩石圈磁场变化与岩石圈结构间的关系

对2016—2019年华北中部地区（34.7°—41.1°N,110.3°—119.7°E）流动地磁矢量观测数据进行处理,得到连续3期岩石圈磁场年变化数据,并对岩石圈磁场空间分布形态进行分析。研究发现,磁异常分布与岩石圈结构之间有一定相关性,在太行山隆起以西、临清坳陷、鲁西断隆和鲁西断隆以东等主要结构单元表现出不同程度的差异性,但在各自单元内却呈现出较好的整体性,岩石圈磁场水平矢量H和东向分量ΔY要素分区特征较明显。从H矢量空间分布形态可以看出,高能量区多分布在太行山隆起以西和鲁西断隆周边。文水—日照ΔY要素剖面幅值变化形态与结构分区间对应较好,对主要结构单元ΔX、ΔY、ΔZ要素异常幅度均值和极值进行统计,结果表明,太行山隆起以西近期岩石圈磁场变化幅度最大,异常能量最强,其次为鲁西断隆及以东地区,而临清坳陷周边磁场变化相对较平稳。