高压引水隧洞衬砌的透水设计研究

国内大都采用荷载结构法及限裂设计的方法对水工高压隧洞的衬砌进行不透水设计。而实践证明,不透水设计并不适合于高压引水隧洞,它将导致过高的配筋量。目前,国内水工高压隧洞结构透水设计尚无适用的规范可循,因此,有必要寻求一种合理、安全的透水设计方法。针对水工高压隧洞,基于体力理论,提出一种对衬砌结构进行透水设计的有限元计算方法,并将其应用于某水电站工程。该方法可模拟隧洞的施工过程和运营检修工况,考虑渗流场和应力场的直接耦合作用,根据内力值计算衬砌裂缝的开展宽度以及相应的配筋量等。通过对比分析,说明在衬砌透水设计中隧洞满水状态为对其进行配筋的控制工况,且结果更符合工程实际,并能大大节省配筋量。     

Root distribution of three co-occurring desert shrubs and their physiological response to precipitation

Root distribution of three desert shrubs,Tamarix ramosissima Ledeb.,Haloxylon ammodendron(C.A.Mey.) Bunge and Reaumuria soongorica(Pall.) Maxim.was investigated under co-occurring conditions using a method for excavating the whole root system.Assimilation shoot water potential and transpiration rates were monitored during the wet-dry cycle.Leaf-specific apparent hydraulic conductance and the index of water stress impact for the three species were calculated from shoot water potential and transpiration rate.The results showed that,along the soil profile,the root system of T.ramosissima mainly distributed at 50 to 310 cm interval,with an average total absorbing root-surface area of 30,249.2 cm2 per plant;the root system of H.ammodendraom distributed at 0 to 250 cm interval with an average total absorbing root-surface area of 12,847.3 cm2 per plant;the root system of R.soongorica distributed at 0-80 cm interval,with an average total absorbing root-surface area of 361.8 cm2.The root distribution shows the following:T.ramosissima uses groundwater as its main water source;H.ammodendraom uses both groundwater and rainwater;and R.soongorica uses rainwater only.During the wet-dry cycle,the hydraulic parameters of T.ramosissima showed no responses to precipitation.R.soongorica responded most significantly,and the responses of H.ammodendraom were intermediate.In conclusion,the plant response to rain events is closely related to their root distribution and plant water-use strategy.     

Effect of Visitor Activities on Surface Soil Environmental Conditions and Aboveground Herbaceous Biomass in Ayder Natural Park

The effects of visitor activities on surface soil environmental conditions and aboveground herbaceous biomass in Ayder Natural Park, Turkey, were investigated. Soil properties and aboveground herbaceous biomass were identified and characterized as heavily trafficked site (HTS), moderately trafficked sites (MTS) and control (non‐trafficked site) in grassland in a forest gap. Some soil properties were measured on 60 pits at 0–5 and 5–10 cm soil depths. The intensity of visitor activities had a negative impact on both surface soil properties and the aboveground herbaceous plant biomass and root mass in the study area in Ayder. The soil bulk density and soil penetration resistance increased from 0.94 to 1.47 g cm^–3 and 0.55 to 1.65 MPa, respectively, saturated hydraulic conductivity decreased from 77.98 to 8.85 mm h^–1, and soil organic matter decreased from 6.71 to 1.77% in moderately and heavily trafficked sites, respectively, at 0–5 cm soil depth. The soil properties were degraded at both the surface layer and the subsurface layer and the greatest degradation was measured in the heavily trafficked site followed by the moderately trafficked site. There was a strong negative linear relationship between soil degradation and aboveground herbaceous plant biomass, which decreased by 50.05 and 78.19% in moderately and heavily trafficked sites, respectively.     

成因机理控制下的低电阻率油层发育特征及地质目标优选

通过建立低阻油层各种岩石物理成因与地质成因之间的关系,结合沉积环境、成岩作用、构造特征和成藏动力因素等综合分析低阻油层的发育特征,提出了5种具有典型意义的低阻油层有利勘探目标区带：（1）小规模、低幅度构造发育区,（2）天然水淹等构造运动活跃、流体非均质严重的区带,（3）岩性细、粘土矿物组合中蒙脱石含量高的区带,（4）弱水动力环境下砂泥岩薄互层发育区,（5）与火山碎屑沉积演化有关的黄铁矿等导电性矿物富集区。以上区带都是低阻油层的勘探目标优选区。由于钻井泥浆与地层水性质不同等侵入原因而造成的油、水层电性标准模糊则属于工程原因所导致的低阻。     

土壤离子电导率方法在云南木利寻找隐伏锑矿的研究

土壤电导率找矿法是利用测定土壤溶液的导电性来发现隐伏矿体的一种找矿新方法.对已知锑矿土壤离子电导率的异常特征研究结果表明,利用该方法在云南木利地区寻找隐伏金矿是可行的.在木利锑矿矿区外围9 km2范围内开展土壤的找矿预测研究,结果找到了3个有利的成矿靶区.     

Topographic controls upon soil macropore flow

Macropores are important components of soil hydrology. The spatial distribution of macropore flow as a proportion of saturated hydraulic conductivity was tested on six humid–temperate slopes using transects of tension infiltrometer measurements. Automated water table and overland flow monitoring allowed the timing of, and differentiation between, saturation‐excess overland flow and infiltration‐excess overland flow occurrence on the slopes to be determined and related to tension‐infiltrometer measurements. Two slopes were covered with blanket peat, two with stagnohumic gleys and two with brown earth soils. None of the slopes had been disturbed by agricultural activity within the last 20 years. This controlled the potential for tillage impacts on macropores. The proportion of near‐surface macropore flow to saturated hydraulic conductivity was found to vary according to slope position. The spatial patterns were not the same for all hillslopes. On the four non‐peat slopes there was a relationship between locations of overland flow occurrence and reduced macroporosity. This relationship did not exist for the peat slopes investigated because they experienced overland flow across their whole slope surfaces. Nevertheless, they still had a distinctive spatial pattern of macropore flow according to slope position. For the other soils tested, parts of slopes that were susceptible to saturation‐excess overland flow (e.g. hilltoes or flat hilltops) tended to have least macropore flow. To a lesser extent, for the parts of slopes susceptible to infiltration‐excess overland flow, the proportion of macropore flow as a component of infiltration was also smaller compared with the rest of the slope. The roles of macropore creation and macropore infilling by sheet wash are discussed, and it is noted that the combination of these may result in distinctive topographically controlled spatial patterns of macropore flow. Copyright © 2008 John Wiley & Sons, Ltd.     

镜泊湖火山台网防雷地网的建设

镜泊湖火山台网位于崇山峻岭之中,经常遭到强雷电袭击。为了使台网设备稳定高效运转,减轻雷电地干扰,我们对台网的防雷设施进行了建设,取得了非常好的防雷效果。     

中国台湾屏东海外7．2级地震前福州乌鸦咀电导率异常分析

通过对福州乌鸦咀泉电导率观测资料的分析,针对2006年4月至10月该测值出现的高值异常现象进行深入分析,并对可能出现的影响因素进行逐个分析排除,认为该异常为中国台湾屏东海外7．2级地震的震前异常。     

基于Tikhonov正则化的双频电磁波电导率成像反演

本文将Tikhonov正则化方法与active-set算法相结合,利用双频电磁波电导率成像原理,求解其反演成像方程.不仅对现有算法进行了改进,也促进了算法的实际应用.本文研究了在双频电磁波电导率成像方程建立后,如何根据其严重病态性质,选择合适的算法求解矩阵成像方程.针对电导率非负的特性,引入正则化参数,将问题转化为一个非负最小二乘问题,并用active-set算法求解.采用改进后的迭代算法对理论模型进行了数值模拟计算,验证了该方法的有效性.应用到实际电导率成像反演,与常规的LSQR、SP-LSQR、Tikhonov正则化等算法进行比较,取得了满意的结果.     

塔里木盆地现今地热特征

地温梯度和大地热流是揭示盆地现今热状态的重要参数,它们对理解盆地的构造-热演化过程及油气资源评价等方面均具有重要意义.利用塔里木盆地约470口井的地层测试温度资料和941块岩石热导率数据,本文计算了塔里木盆地38个新的大地热流数据,进而揭示了该盆地现今地热分布特征.研究表明,塔里木盆地现今地温梯度变化范围为17～32 ℃/km,平均为22.6±3.0 ℃/km;大地热流变化范围为26.2～65.4 mW/m²,平均为43.0±8.5 mW/m².与我国其他大中型沉积盆地相比,它表现为低地温、低大地热流的冷盆的热状态,但仍具有与世界上典型克拉通盆地相似的地热背景.整体而言,盆地隆起区地温梯度和热流相对较高,坳陷区地温梯度和热流则偏低.此外,我们还发现塔里木盆地现有的油气田区一般位于高地温梯度区域,这可能与下部热流体的向上运移和聚集有关.影响塔里木盆地现今地热特征的因素包括盆地深部结构、构造演化、岩石热物理性质、盆地基底构造形态和烃类聚集等.