地裂缝-隧道-围岩动力相互作用模型试验研究

为了研究在地铁列车振动荷载情况下盾构隧道-地裂缝-围岩相互耦合作用下的场地灾害效应,从西安地裂缝地质环境和西安地铁2号线的实际工程背景出发,采用相似理论设计了相似比例尺为1∶5的物理模型试验,对盾构隧道、围岩材料、地裂缝等进行了合理设计。基于偏心块的振动原理,课题组自主研发了列车激振器来模拟地铁列车荷载,激振方式采用移动荷载激振方式,分析在不同列车车速和激振频率下地裂缝两侧土体的加速度变化情况,以此来研究地铁隧道-地裂缝-围岩系统在地铁振动荷载作用下的动力响应规律。结果表明,列车振动向下传播时振动衰减的幅度要小于向上传播衰减的幅度,由此为实际工程中减少地铁振动灾害效应技术的发展提供了理论支撑。     

Fluid inclusion and H–O–C isotope geochemistry of the Yaochong porphyry Mo deposit in Dabie Shan,China: a case study of porphyry systems in continental collision orogens

The Yaochong porphyry Mo deposit in Xinxian County, Henan Province, China, is located in the Hong’an terrane, that is, the western part of the Dabie orogen. The Dabie orogen is part of a >1,500 km long, Triassic continental collision belt between the North China Block and the South China Block. Four types of vein are present. Paragenetically, from early to late, they are as follows: stage 1 quartz + K-feldspar ± pyrite ± magnetite vein; stage 2 quartz + K-feldspar + molybdenite ± pyrite vein; stage 3 quartz + polymetallic sulfides ± K-feldspar vein; and stage 4 quartz ± carbonate ± fluorite vein. Four compositional types of fluid inclusion, pure CO₂, CO₂ bearing, aqueous, and solid bearing, are present in quartz from the first three stages; only low-salinity aqueous fluid inclusions occur in quartz from the last stage. All the estimated salinities are ≤13.1 wt% NaCl eq., and no halite crystals were identified. Homogenization temperatures for the fluid inclusions from stages 1 to 4 are in the ranges of 262–501, 202–380, 168–345, and 128–286 °C, respectively, and estimated depths decrease from 6.9 to 8.9 km, through 6.2–7.2, to ~4.7 km. Quartz separates from the veins yielded a δ¹⁸O value of 7.7–11.2 ‰, corresponding to δ¹⁸O_H2O values of ?1.3 to 6.9 ‰ using temperature estimates from fluid inclusion data; δD_H2O values of fluid inclusion vary from ?80 to ?55 ‰, and δ¹³C_CO2 from ?2.3 to 2.7 ‰, suggesting that the ore-fluids evolved from magmatic to meteoric sources. We conclude that the ore-forming fluid system at Yaochong was initially high temperature, high salinity, and CO₂-rich and then progressively evolved to CO₂-poor, lower salinity, and lower temperature, by mixing with meteoric water, which results in ore precipitation.     

近地层组合法确定湍流通量精度的研究

近地层组合法的实质是将廓线法和地面能量平衡方程联立而计算湍流参数和通量的一种方法。本文利用实测的脉动场和平均场的同步梯度资料研究组合法的精确性及其应用价值。     

应用E-ε湍流动能闭合湖泊热力学过程模型对东太湖湖-气交换的模拟

采用考虑沉水植物影响的E-ε湍流动能闭合湖泊热力学过程模型,模拟2013年8月东太湖湖-气交换过程,并利用太湖的站点观测数据对模型进行了验证。太湖水温的模拟值与观测值吻合较好,模型计算的各层水温与观测值相比,均方根误差均未超过1℃。同时模型也较好地模拟出太湖表面感热通量和潜热通量,潜热通量的模拟值与观测值的标准差为54.7 W/m²。由于湖水较浅,太湖的水温层结会明显受到天气状况的影响。晴朗小风条件下的湖水呈现显著的热分层现象,当风速为0.8 m/s,高层和底层的温差达到7.9℃。大风天气条件驱动较强的水体湍流混合,水温的热分层消失,风速为12 m/s,湖泊上层与底层的水温差仅0.12℃。此外,模拟结果较好地呈现出了东太湖沉水植物的存在通过增大湖体消光系数,减小到达湖体内部的热量,并增加对湖水的阻力,影响湖体中湍流动能的分布,并进而影响湖水温度的分布。综上所述,该模型能够较好地模拟出浅水大湖湖-气交换的过程。     

西太平洋副热带高压强度和东亚地表热通量的年代际变化特征及关系

利用NCEP/NCAR的月平均再分析资料以及中国国家气候中心的西太平洋副热带高压(副高)强度资料,分析了西太平洋副高强度、500hPa环流场以及东亚地表感热、潜热通量场的年代际变化特征,发现各个季节的西太平洋副高强度及其环流形势均存在一定的年代际变化,变化发生的时间为1978年前后,20世纪70年代中期以后副高强度有所增强。副高强度在季节间的延续性也发生了一定的年代际变化,1978年以后季节间的延续性增强,全时段的延续性受后一时段的影响较大。东亚地表感热、潜热通量场也存在明显的年代际变化,感热通量的变化关键区在大陆上,主要为青藏高原东、西部,其发生年代际变化要早于西太平洋副高强度变化的时间(20世纪60年代中后期),但它们发生差异变化的时间则接近西太平洋副高强度发生年代际变化的时间,在20世纪60年代中后期以前,高原感热通量体现为稳定的西高东低,而20世纪70年代中期以后则转为稳定的东高西低,其中,近10年时间为调整过渡期,因此,它们各自的年代际变化所造成的影响会有所滞后。潜热通量的变化关键区则位于海洋上,主要是西太平洋地区,1978年以前春季地表潜热通量距平为南正北负,之后转为南负北正,而夏季潜热通量距平则...     

Study On Development And Application Of A Regional Pbl Numerical Model

A regional scale (a few km to a few hundred km, minutes to days)planetary boundary layer (PBL) numerical model (RPBLM) has been successfully developed to simulateprecisely the boundary-layer three-dimensional characteristics. The RPBLM model with a high-resolutionnon-hydrostatic E - turbulence closure scheme has been applied to diagnose and prognosticate the PBL characteristicsover a complex underlying surface in the Hong Kong area of 60 km × 48 km. It is shown that the RPBLMmodel can be used to simulate the PBL characteristics including wind, temperature, water vapour andturbulence over such a complex underlying surface and that the simulated result is reasonably in agreementwith observations.     

精细PBL模式及其诊断应用

在已建立的一种三维非静力细网格Ｅ－ε湍能闭合的动力学框架基础上,作了一些改进的技术处理和试验,包括：（１）利用ＧＩＳ提供的地形资料,较精确地计算太阳辐射,进而诊断地面温度;（２）引进位势流概念,处理稳定层结条件下初始内插风场的风向变化;（３）引入动力学调整项Ｇ（αｏｂｓ－α）。在此基础上,就地理信息系统（ＧＩＳ）提供的一个 ６０ｋｍ×４８ｋｍ区域作了边界层结构和湍流特征的数值模拟试验,并与实测作了比较,讨论了精细ＰＢＬ模式的模拟效果,结果表明,新建的ＰＢＬ模式能较好地模拟表征出复杂下垫面地域的陡峭地形和不规则海岸线对局地风场和湍流场的动力和热力学作用。     

东亚下垫面热力异常与南海夏季风爆发早晚和强弱的关系

利用我国南方逐日降水资料及逐月温度资料，采用Mann-Kendall 突变检验方法，并计算极端降水的GPD(Generalized Pareto Distribution)重现值，讨论了气候变暖前后我国南方冬季极端降水事件的变化。结果表明，我国南方冬季气候变暖的突变发生在1991年前后，且气候变暖后我国南方冬季的极端降水强度普遍有所增加。利用NCEP/NCAR再分析资料进一步分析气候变暖前后的环流场特征，发现东亚热带冬季风异常与我国华南、江南地区降水异常有显著的相关关系。东亚热带冬季风偏强(弱)，华南、江南地区降水偏少(多)。气候变暖后中高纬度环流经向度加大，有利于北方的冷空气向南输送。此外, 气候变暖后我国南方地面气温升高，海陆热力差异减小，东亚热带冬季风减弱，有利于西太平洋的暖湿气流向我国大陆东南部输送，并在东南部形成异常的水汽通量辐合，有利于形成强降水。气候变暖后，中高纬度与中低纬度异常环流系统的相互作用是我国东南部降水强度增加的主要原因。     

Impact of incident angles of P waves on the dynamic responses of long lined tunnels

The impact of the incident angle of earthquake motion on the seismic response of the long lined tunnels is studied. Based on the time‐domain finite element method with the viscous‐spring artificial boundary condition, the earthquake motion of oblique incidence is transformed into the equivalent nodal forces acting on the truncated boundary of finite element model. In the present work, the formulas of equivalent nodal forces for the plane P wave with arbitrary incident angle are deduced and implemented into the commercial software abaqus   1 . The effectiveness of the formulas and its implementation are demonstrated by two numerical examples with the reference solutions. The proposed method is applied to investigate the seismic responses of the long lined tunnels under the obliquely incident P waves. The numerical results indicate that the seismic responses of the long lined tunnels are highly affected by the incident angles of P waves. Copyright © 2016 John Wiley & Sons, Ltd.     

The statistical study of precursory anomalies observed in Chinese Seismological Network

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