A Method for Automatically Selecting Aids to Navigation Based on their Spatial Influence Domains

To address the limitations of manually selecting aids to navigation (AtNs) on charts, a method for automatically selecting AtNs based on their spatial influence domains (SIDs) is proposed. First, the associations between the spatial attributes of an AtN are analyzed. Second, an SID of the AtN is defined, and a model of the SID is constructed based on the associations between the spatial attributes. Third, the importance of the location of the AtN is weighted based on the SID model. Fourth, an algorithm to automatically select AtNs based on the maximum coverage of the SIDS of preselected AtNs is developed. Finally, several AtNs are selected automatically using the algorithm. The experimental results demonstrate that (1) the proposed method can automatically select AtNs and the results comply with the requirements; (2) the automatic selection can eliminate the human-induced errors or the inconsistent results of manual selections from different operators; and (3) the efficiency of the proposed method is higher than that of current manual methods.     

Nonparametric Estimation of Undrained Shear Strength for Normally Consolidated Clays

For decades, various well-known empirical correlations have been established and commonly used to estimate the undrained shear strength of normally consolidated clays in geotechnical practice. However, there are still many contradictory cases regarding the validity of these correlations, so their applicability and reliability are questionable. In this study, an extensive geotechnical database for normally consolidated clays has been compiled. Next, a Bayesian nonparametric method is exploited to identify the most critical soil index properties in inferring the undrained shear strength and a new predictive model is proposed. Finally, the performance of the proposed predictive model is assessed and compared with two well-known correlations using an independent testing database. It confirms that the proposed model not only possesses high predictability, but also provides superior performance over other existing empirical correlations.     

油铀兼探的找矿思路在松辽盆地的应用——以中央拗陷区南部为例

以"油铀兼探"的找矿思路,带动松辽盆地中南部开展砂岩型铀矿调查选区及钻探验证工作.将异常强度250 API和450 API确定为划分潜在铀矿孔、潜在铀矿化孔和正常孔的关键技术指标,对中央拗陷区南部1572个钻孔进行异常筛查工作.排查发现潜在铀矿孔362个,潜在铀矿化孔223个.对191号钻孔和36号钻孔进行钻探验证,发现1个工业孔、1个异常孔.认为区内寻找砂岩型铀矿的有利地段为油田区反转构造形成的隆起区边部四方台组河流相砂体,并总结了中央拗陷区南部6种主要控矿因素.     

Landfill site selection based on reliability concepts using the DRASTIC method and AHP integrated with GIS – a case study of Bengaluru city,India

The selection of landfill sites for municipal solid waste (MSW) disposal involves consideration of geological, hydrological and environmental parameters which exhibit large spatial variability. Therefore, it is necessary to define, to what extent the chosen sites are reliable such that the probability of environmental pollution and health risks to population is minimal. In the present study, groundwater vulnerability to contamination has been assessed using the standard DRASTIC method. The results showed that the study region has 9.45% of very less, 32.94% of less, 25.47% of moderate, 22.79% of high and 9.35% of very high vulnerable zones. The study also revealed that none of the landfills are located in safe zones. This suggests that it requires proper remedial measures to avoid environmental pollution. A landfill site selection process has been carried out using the Analytical Hierarchy Process integrated with Geographical Information System tools. The obtained results showed that only 3.59?km² (0.08%) of the total area is suitable for landfills. The reliability analysis of the site suitability revealed that landfills are located at unreliable locations where the probability of risk to environmental pollution is high. The presented approach assists decision-makers in selecting reliable locations for the safe disposal of MSW.     

川滇黔邻区龙马溪组页岩气富集主控因素与勘探方向

中国的页岩气资源评价必须立足于中国主要陆块的地质条件与构造演化特点之上,对于不同层系、不同地区的页岩气选区评价,也必须抓住关键因素。川滇黔邻区的五峰组-龙马溪组富有机质页岩发育,但保存条件较渝东南地区更为复杂。印支期以来,该区经历了多期次构造应力场转换,断裂、褶皱发育,因此,建立针对性的页岩气选区评价参数体系是该区页岩气勘探走出困局的当务之急。本文在分析该区已有页岩气钻井成效的基础上,立足于扬子海相层系页岩气勘探应是基于保存条件的"连续型甜点区"的选区评价基本思路,结合前人研究成果,系统梳理出一套评价指标体系。该体系涵盖5大因素(区域盖层、直接盖层、底板条件、页岩层自身条件、构造改造强度)、4个等级、17个选区评价参数。另外,根据已有相关钻井数据,总结提出了5个页岩气层评价表征参数(含气量、孔隙度、电阻率、氮气组分含量和压力系数)。根据该指标体系,对川滇黔邻区的主要构造单元进行了梳理分析,优选出5个有利区,提出了各有利区的首选可能突破点。本研究对复杂构造区页岩气有利区带优选具有一定的指导意义。     

孔隙性砂岩中单条变形带与簇状变形带的特征与区别——以远安地堑上白垩统红花套组中变形带为例

孔隙性砂岩中的变形带研究近年来取得长足进展,但有关单条变形带与簇状变形带如何区分和界定仍是一个较模糊的问题。本文以远安地堑上白垩统红花套组高孔砂岩中发育的剪切增强压实带和压实剪切带为例,对单条及簇状变形带的特征和区别做出系统分析。研究表明,虽然单条变形带的长度、宽度、错断位移、凸起高度等均明显小于簇状变形带,但是不同运动学成因的变形带宏观特征、微观结构不同,因此不能单纯以规模大小区分二者,需要结合带密度将簇状变形带与变形带列、网格构造等相区分,还需要结合其微观结构特征进行准确鉴定。单条及簇状剪切增强压实带特征类似,均不具核心碎裂带,颗粒主要为中等破碎,多表现为多个不连续分布的碎裂核。簇状剪切增强压实带内部的非均质性更强。单条压实剪切带具有核心碎裂带,依剪切力大小不同,其核心碎裂带内颗粒粉碎程度及边缘过渡带宽度不同,常伴随微小剪切缝痕迹。簇状压实剪切带在镜下可清晰识别出不同的核心碎裂带、带间区域及微小剪切缝,可见S—C组构和断续分布的滑动面。单条及簇状变形带的发育会不同程度地改变储层的物性并可能会对油气运移和开采产生影响。     

海上油田开发井钻井优化设计和应用实践

LF7-2油田位于我国南海珠江口盆地LF区块,是一个小规模油田,根据前期探井揭示,上部地层以厚层泥岩为主,极易水化、分散,使钻井液性能变差;起下钻过程中钻具遇卡、遇阻等复杂情况频繁发生;钻头选型不尽合理,易泥包;下部地层以砂泥岩互层为主,岩石致密、可钻性变差,钻具扭矩、摩阻增加,定向钻进时滑动困难,井眼轨迹控制难度大,给钻井提速增效带来诸多困难。根据探井地质情况和岩石力学剖面,利用钻井软件优选平台位置,对开发井井身结构、井眼轨迹、钻柱力学、钻井液、固井等方面进行钻井仿真模拟,制定出科学的钻井设计方案,在直井段采用“牙轮钻头+直螺杆+MWD”钻具开展防斜打直,造斜段使用“PDC钻头+弯螺杆+MWD/LWD”开展复合钻井,水平段采用“PDC钻头+PowerDriver+MWD/LWD”开展旋转导向钻井,实现精准化钻井,顺利完成6口开发井施工。现场应用单井平均机械钻速29.43 m/h,钻井工期191.59 d,工期比设计提前28.41 d,钻井提速增效显著,降低开发成本。通过PowerDriver的近钻头井斜、自然伽马实时测量和传输,减少地质误判,实现对储层顶界面的实时探测,使储层钻遇率达100%,收到较好的经济效益和投资回报,实现小油田的效益开发。     

天陇铁路上倪滑坡工程地质特征分析及地质选线

在天陇铁路勘察设计工作中,发现上倪滑坡是新建天水至陇南铁路一处控制性不良地质体。本文在充分获取地质资料的基础上,从地形地貌角度出发,结合其地层岩性特征,分析了滑坡成因,认为上倪滑坡在北侧和南侧各存在一个软弱面,滑坡整体稳定性较差,尤其是滑坡北侧危险性较大。通过力学计算,显示该滑坡自然状态下能够保持相对稳定,但在地震或暴雨天气下发生滑动的可能性极大,对线路工程具有严重影响。经过对三种线路方案的综合比选,建议以深埋隧道形式从后壁通过上倪滑坡,保证工程安全性。     

2017年6月一次华南沿海强降水的对流性特征及热动力机制研究

在华南北部或长江流域有锋面雨带活动时,华南沿海常常会出现对流性强降水,突发性很强,给预报造成很大的困惑。文章采用多种观测资料、ERA-Interim 0.125°×0.125°逐6 h再分析资料,对2017年6月15～16日华南北部的锋面雨带及沿海强降雨过程开展分析,对比了二者降水特征与环境条件,重点探讨了该次过程华南沿海强降雨的对流触发与维持,揭示了一种由边界层风切变强迫造成涡度持续发展的动力效应。结果表明:（1）锋面雨带与华南沿海强降雨在降水特征上有显著差异,并各有特点。锋面雨带以大尺度层状云降水和弱对流性降水为主,降水强度东段弱西段强。沿海强降雨以对流性降水为主,局地性强、落区集中、强降雨持续时间长、夜发性明显。（2）水汽方程诊断发现沿海强降雨在边界层水平水汽平流项、垂直水汽输送项比锋面雨带东段具有更大量级,大气层结反映出更深厚的暖层、湿层与对流不稳定,是二者降水强度及性质差异的主要原因。（3）莲花山、峨眉嶂造成气流侧向摩擦与正面阻挡促使漯河河谷内垂直涡度发展,暖湿空气堆积上升并达到自由对流高度,触发了华南沿海最初的降水。夜间建立的西南风急流使边界层垂直风速切变增强,水平涡度倾斜部分转化为垂直涡度发展,与风速水平切变造成的垂直涡度叠加,是强降雨持续时间长的动力机制。海陆边界摩擦差异造成水平、垂直两个方向的风切变增强,共同强迫垂直涡度发展是此次强降雨过程对流维持的动力效应。（4）方程诊断表明华南沿海强降雨由对流潜热释放造成的垂直上升速度占总垂直上升速度的39%～75%,持续、稳定的对流潜热释放是强降雨持续时间长的热力驱动因素。     

CINRAD-SA双偏振雷达资料在降水估测中的应用初探

对基于水平反射率ZH和差分传播相移率K_(DP)的降水估测综合法R(C)进行了改进,并对广州S波段双偏振雷达2016年2次飑线和2次台风降水过程的Φ_(DP)使用小波分析进行滤波处理,在此基础上使用变距最小二乘法拟合得到K_(DP)的值。分别使用R(C)和R(Z_H)法对2次飑线和2次台风降水过程进行降水估算,将估算结果和雨量计小时雨量进行了对比,并将两种方法的评估结果进行了对比。结果表明:(1)对于飑线类型降水,R(C)法对5 mm·h~(-1)以上的降水估测精度要好于R(Z_H)法,且降水率越大,R(C)法优势越明显,当降水率≥20 mm·h~(-1)时,两次过程R(C)法比R(Z_H)法的平均相对误差(RE)降低了17. 2%,平均绝对误差(AE)减少了1.89 mm,平均均方根误差(RMSE)减少了1.66 mm;(2)对于台风类型降水,R(C)法对5 mm·h~(-1)以上的降水估测精度也好于R(Z_H)法,当降水率≥20 mm·h~(-1)时,两次过程R(C)法比R(Z_H)法的平均RE降低了33. 19%,平均AE减少了3. 95 mm,平均RMSE减少了4.05 mm;(3)对于飑线和台风两种类型降水R(C)法都明显改善了降水率较大时的R(Z_H)法低估问题,但R(C)法在降水率10 mm·h~(-1)时也存在低估,可能是由雨滴谱资料观测误差导致拟合的系数偏小或雷达硬件造成的观测偏差等造成的。