Three‐dimensional shakedown solutions for anisotropic cohesive‐frictional materials under moving surface loads

Previous work on three‐dimensional shakedown analysis of cohesive‐frictional materials under moving surface loads has been entirely for isotropic materials. As a result, the effects of anisotropy, both elastic and plastic, of soil and pavement materials are ignored. This paper will, for the first time, develop three‐dimensional shakedown solutions to allow for the variation of elastic and plastic material properties with direction. Melan's lower‐bound shakedown theorem is used to derive shakedown solutions. In particular, a generalised, anisotropic Mohr–Coulomb yield criterion and cross‐anisotropic elastic stress fields are utilised to develop anisotropic shakedown solutions. It is found that shakedown solutions for anisotropic materials are dominated by Young's modulus ratio for the cases of subsurface failure and by shear modulus ratio for the cases of surface failure. Plastic anisotropy is mainly controlled by material cohesion ratio, the rise of which increases the shakedown limit until a maximum value is reached. The anisotropic shakedown limit varies with frictional coefficient, and the peak value may not occur for the case of normal loading only. Copyright © 2013 John Wiley & Sons, Ltd.     

抚顺地区夏季降水异常的气候特征分析

利用1951—2012年NCEP/NCAR再分析月平均资料及章党观测站月平均降水数据,利用统计学方法从大气环流等方面对抚顺地区夏季降水异常气候特征进行了分析探讨。结果表明:抚顺地区夏季降水存在明显年际尺度周期特征,西太平洋副热带高压北界越偏北、强度越强则抚顺地区降水强度越大。抚顺地区降水强(弱)年,500hPa高度场抚顺地区位于距平低涡(高压)底前部,850hPa风场抚顺地区处于西南(偏北)气流控制之下,海平面气压场抚顺地区位于蒙古气旋底前部(反气旋前部),比湿场抚顺位于比湿距平正值(负值)区内。降水强年的温度场距平低值中心落后于500hPa高度场低值中心,利于高空槽的发展,有利于降水的维持加强,降水弱年的温度场距平低值中心与500hPa高度场低值中心相配合,对高空槽脊的发展无明显的影响。     

断层EDF技术在复杂断块构造研究中的应用

复杂断块构造具有断层复杂,小断层广泛发育,断层识别难度大,储层分布及连通性复杂,地震成像不清、资料品质较差等特征。对于此类问题,常规地震资料无法满足断层解释精度要求。提出了一种新的断层EDF解释性处理技术,将地震资料处理与解释融为一体,以提高资料的信噪比和断层的识别能力。断层EDF解释性处理技术是利用扩散滤波和中值倾角滤波相结合的断层增强滤波方法来提高资料的信噪比,突出断层和地层的接触关系,再在滤波后的地震资料数据体上进行分频处理,选择最佳成像频带,突出识别不同规模的断层。通过在涠洲A油田的应用,取得了良好的效果。     

贵州铜仁松桃锰矿国家整装勘查区地质找矿主要进展及潜力预测

贵州铜仁松桃锰矿国家整装勘查区位于扬子地块东南缘的武陵山成矿带。著名的南华纪大塘坡早期(660-667 Ma)"大塘坡式"锰矿,形成于Rodinia超大陆裂解背景下的南华裂谷盆地。近年来,项目团队在该国家整装勘查区及黔渝湘毗邻区,通过长期的产学研协同攻关,厘清了锰矿大规模成矿作用的独特地质背景和构造古地理格架,发现了新的锰矿床类型——古天然气渗漏沉积型锰矿床,建立锰矿裂谷盆地古天然气渗漏成矿理论和深部隐伏矿找矿预测模型,圈定了若干找矿靶区。通过该整装勘查区的实践检验,累计投入各类勘查资金6亿多元,先后新发现了松桃西溪堡(普觉)、松桃道坨、松桃高地和松桃桃子坪四个隐伏超大型锰矿床。该整装勘查区新发现的超大型锰矿床数,占全球已发现超大型锰矿床总数约三分之一。新发现的锰矿资源量,超过了2011年全国锰矿保有资源量的总和,实现了我国有史以来锰矿找矿的最大突破,且锰矿找矿潜力依然巨大。使黔东成为中国锰矿资源最丰富的地区和新的世界级锰矿资源富集区。古天然气渗漏沉积型锰矿床成为中国最重要的锰矿床类型,是继传统的海相沉积型、沉积变质型锰矿床类型之后,全球最重要的三大锰矿床类型之一。     

Two new species of the genus <Emphasis Type="Italic">Cobitis</Emphasis> Linnaeus (Teleostei: Cobitidae) from southern China

Two new species of the genus Cobitis from southern China, C. hereromacula from the Luohe River in Guangdong Province and C. baishagensis from the Nandujiang River in Hainan Province, are described and illustrated here. C. hereromacula can be distinguished from its congeners by possessing the following combination of characteristics: absence of the second and third pigmentary zones of Gambetta; 13–16 oval blotches on the dorsum and 10–13 vertical, elongated triangular blotches below the midlateral line with more than 20 vertical dark brown bars between them; 6–7 narrow rows of dark spots on the caudal fin; a vertical oval spot smaller than the eye diameter on the upper part of the caudal peduncle; pointed mental lobes of the lower lip pointed with a slightly filiform tip; one slender and long needle-shaped lamina circularis at the base of the first branched ray of the male pectoral fins. C. baishagensis can be distinguished from its congeners by the fourth Gambetta zone being covered by 10–12 transverse elongated blotches; 4–5 narrow rows of dark spots on the caudal fin; a vertical blotch smaller than the eye diameter on the upper part of the caudal peduncle; males with a slender and long needle-shaped lamina circularis at the second branched pectoral fin ray in males; large scales with a slightly large focal zone; undeveloped mental lobes with a lower lip that does not end posteriorly in a filiform tip.     

贵州松桃大屋锰矿床主要地质特征与找矿预测

松桃大屋锰矿是贵州省地矿局103地质队于上世纪70年代勘查评价的中型锰矿床。锰矿产于南华系大塘坡组第一段黑色岩系底部,矿体呈层状、似层状产出,矿层走向北东约70°,矿体平均厚1. 42 m,平均品位18. 85%。矿区从北西向南东,含锰岩系、锰矿体从无到有。大屋锰矿床只保留了古天然气渗漏沉积成矿系统中的过渡相和边缘相,中心相应在齐公坡一带,但已被剥蚀殆尽。通过构造古地理恢复分析,推测南华纪大屋地堑盆地长大于14 km、宽约4 km,沿北东70°方向展布。预测盆地北东柳树塘、大坳至孟溪一带还具有发现中-大型规模锰矿床的潜力。     

贵州松桃高地特大型富锰矿床主要地质特征

位于贵州铜仁松桃国家锰矿整装勘查区内的高地富锰矿床,(332)+(333)类碳酸锰富锰矿石资源量达7 166. 84万吨,锰平均品位25. 75%,矿体平均厚度4. 52 m,富锰矿体赋存于总资源量达1. 61亿吨的高地超大型锰矿床之中,由一个单一的富锰矿体构成,是我国新发现的首个特大型富锰矿床,富锰矿资源量相当于我国富锰矿资源量总和的2倍。成因类型属古天然气渗漏沉积型锰矿床,富锰矿产于古天然气渗漏沉积成矿系统中心相区。高地富锰矿床地处独特的"新月形"南华纪早期李家湾-高地-道坨(Ⅳ级)地堑盆地中心,菱锰矿体中均出现以块状构造夹被沥青充填的气泡状富菱锰矿石。地表燕山期北北东向的断裂构造十分发育,但主要为上陡下缓犁式正断层,未触及高地深部隐伏巨型锰矿体,以致富锰矿体保存亦十分完整,易于开发利用。     

黔东及毗邻地区南华纪锰矿成矿期与成矿后构造专项填图方法研究

黔东及毗邻地区南华纪锰矿成矿期构造主要为同沉积断层,该类型断层在成矿期十分发育,控制和形成了南华纪早期不同序次的次级裂谷盆地,同沉积断层的垂向发育形成了锰矿成矿通道,同沉积断层可作为古天然气渗漏沉积型锰矿床关键地质找矿标志,本文阐述了其主要判别特征。南华纪锰矿形成后,历经加里东运动、印支运动及燕山运动等构造运动,总体来说,该区构造格局主要是受到燕山运动影响形成。本文也讨论了研究区成矿后广泛发育且比较典型,对锰矿层保存与破坏有着较大影响的犁式正断层及其判别特征。     

Estimating satellite phase fractional cycle biases based on Kalman filter

Phase fractional cycle biases (FCBs) originating from satellites and receivers destroy the integer nature of PPP carrier phase ambiguities. To achieve integer ambiguity resolution of PPP, FCBs of satellites are required. In former work, least squares methods are commonly adopted to isolate FCBs from a network of reference stations. However, it can be extremely time consuming concerning the large number of observations from hundreds of stations and thousands of epochs. In addition, iterations are required to deal with the one-cycle inconsistency among FCB measurements. We propose to estimate the FCB based on a Kalman filter. The large number of observations are handled epoch by epoch, which significantly reduces the dimension of the involved matrix and accelerates the computation. In addition, it is also suitable for real-time applications. As for the one-cycle inconsistency, a pre-elimination method is developed to avoid iterations and posterior adjustments. A globally distributed network consisting of about 200 IGS stations is selected to determine the GPS satellite FCBs. Observations recorded from DoY 52 to 61 in 2016 are processed to verify the proposed approach. The RMS of wide lane (WL) posterior residuals is 0.09 cycles while that of the narrow lane (NL) is about 0.05 cycles, which indicates a good internal accuracy. The estimated WL FCBs also have a good consistency with existing WL FCB products (e.g., CNES-GRG, WHU-SGG). The RMS of differences with respect to GRG and SGG products are 0.03 and 0.05 cycles. For satellite NL FCB estimates, 97.9% of the differences with respect to SGG products are within ±?0.1 cycles. The RMS of the difference is 0.05 cycles. These results prove the efficiency of the proposed approach.