浸泡作用下碎石土剪切强度衰减规律及机理

水库蓄水后,滑坡体碎石土经受长时期的浸泡,力学性质发生改变,从而影响滑坡整体稳定性。为探究浸泡对碎石土力学性质的影响规律,选取三峡库区马家沟滑坡后缘未经受长期浸泡作用的碎石土进行大型直剪试验,分析了不同浸泡天数下碎石土的剪切力学性质。试验结果表明：浸泡40 d后,碎石土黏聚力下降幅度达39%,内摩擦角下降幅度为8.3%;碎石土黏聚力在浸泡前期快速下降,下降速率随浸泡天数增加而降低,浸泡20 d后,黏聚力基本达到稳定。为探究碎石土抗剪强度降低的原因和机理,对粉质黏土(碎石土细粒成分)进行了三轴剪切试验、激光粒度分析及浸出液阳离子分析等试验,揭示了碎石土抗剪强度的衰减机理为：浸泡作用下,碎石土中的粉质黏土发生矿物溶解、离子交换与吸附作用,土体中大颗粒细化,胶结作用减弱,进而导致碎石土整体抗剪强度降低。研究结果对库区碎石土滑坡评价与治理具有一定的指导意义。     

The flood of the Nenjiang river and the Songhua river in 1998 and the comprehensive management of the river basins

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CONTENT AND DISTRIBUTION OF TRACE ELEMENTS IN SOILS OF THE DAM RIVER AND TUOTUO RIVER BASINS

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Distribution and mechanism of gently dipping fractures subjected to river incision: A case study from Nujiang River,China

Gently dipping fractures subjected to river incision are widely distributed on rock slopes. In this paper, a rock slope on the Nujiang River (China) is investigated to study the role of gently dipping fractures in the rock slopes evolution. Detailed field surveys indicate that gentle fractures are concentrated in four main zones. Moreover, the kinematics of the fracture system suggest that the genesis of these fractures can be synthesized into a progressive evolution model. This model indicates that the joints begin with the formation of an array of en echelon cracks that are subjected to continued crack elongation and shearing before ultimately approaching one another and interacting to form a complex joint system. Geomechanical analysis is performed to reveal the mechanisms of this genesis, and three main fracture patterns are identified based on the slope stress and are classified with respect to the slope evolution. Based on the detail field investigations and the evolutionary history of the river valley, we propose that intermittent incision by the river was the main factor contributing to the concentrated distribution of gently dipping joints.     

利用SH横波反射资料中的勒夫面波反演浅部横波速度结构

由于勒夫波速度与纵波速度无关,勒夫波多道分析方法具有频散曲线简单、能量清晰、反演过程中未知参数少、对初始模型依赖小、反演结果稳定、分辨率高等特点。实验结果表明,利用浅层SH横波反射地震数据中的勒夫面波信息,反演得到近地表横波速度结构,在浅层地质构造、断层位置、上断点埋深等方面与浅层SH横波反射地震剖面以及地质钻孔数据吻合较好。该方法可为地下构造解释提供更多依据,提高探测成果的可靠性。     

南京市高温热浪时空分布研究

在全球气候变暖的背景下,城市夏季高温热浪已经成为城市最严重的气象灾害之一,给城市居民健康和经济发展带来了巨大的影响。以2013年8月7日-13日的南京高温热浪灾害事件为例,基于Landsat 8 OLI 卫星遥感数据、MODIS卫星遥感数据和气象站点数据,在MODIS地表温度降尺度基础上,估算近地表气温,进而结合空气相对湿度的空间插值数据计算南京地区100 m分辨率的炎热指数和高温热浪指数,分析其时空分布特征。结果表明：在这次高温热浪演变过程中,南京炎热指数呈现先升高后降低的变化趋势,8月11日炎热指数最高,平均达到86.99,12日降到最低值,平均值为85.05;高温热浪强度主要集中于轻度热浪与中度热浪,随着时间的推移,其范围也呈现先扩大后减小的趋势;在空间分布上,南京北部及中心城区的炎热指数较高,主要表现为中度热浪,而南部地区及中心城区周边郊区较低,主要为轻度热浪,山体和水域炎热指数则最低,多为无热浪。     

唐山地区波速比变化特征研究

选取唐山地区2008~2018年震相数据,利用单台多震和达法和多台多震和达法分别计算波速比,结合研究区内的地震活动对波速比的变化特征进行研究。结果显示,多台多震和达法得到的波速比结果较为稳定,而单台多震和达法得到的结果变化幅度大,显示更多细节;唐山地区ML≥4.5地震发生前单台波速比存在不同程度的异常,异常台站的方位与地震具有一定的对应性。     

基于双相介质的地震波衰减特性油气检测方法

油气储层是典型的多相介质,目前油气检测中依据的单相介质理论容易造成预测结果的多解性。为了更准确地检测油气,以Biot双相介质理论为基础,推导吸收系数表达式,建立能量密度衰减方程,利用广义S变换对地震资料进行频谱分解,分析介质含不同流体后地震波各频率成分的衰减特征。结果表明:当双相介质中所含流体性质不同时,地震波的频率衰减也不尽相同,当储集层中含油气时,地震波频率衰减量显著增大,低频能量衰减小,高频能量衰减大,在频谱上表现为低频能量相对增强,高频能量相对减弱,整体能量向低频移动。对比实际工区的低、高频能量剖面和衰减剖面,将地震波的衰减规律运用到油气检测中取得较好的效果,理论模型和实际资料的运用表明该方法可行。     

地震波在强夯地基测试中的应用研究

利用已知钻探、原位测试、土工试验的资料,构建地震波速度与地基土物理指标的关系,并以此作为已知输入,在同一地震排列中分别拾取瑞雷波、纵波速度。以地震波速度划分为速度层,根据已知输入确定地基土的密实度、均匀性、承载力等物理力学指标。     

注浆法在黄土地区公路路基洞穴处理中的应用

研究了注浆法在黄土地区公路路基洞穴处理中的加固机理及技术指标.黄土地区公路中的洞穴对公路的安全运营常造成严重危害,同时对于这类洞穴的处理尚缺乏有效的方法.在大量调查和参考前人研究成果的基础上,将注浆法用于路基中洞穴的处理,提出了注浆法加固的主要设计参数,通过对施工现场黄土洞穴注浆处理效果分析,认为该方法具有良好的处理效果.     

隧道地震预报中基于遗传算法的波动方程反演

首先建立一维波动方程反演的数学模型,而后引入交错网格有限差分正演模拟,最后将遗传算法和交错网格差分正演结合,实现波动方程遗传算法的反演;针对数值模拟合成的单道记录,应用波动方程遗传算法反演分析各参数对反演结果的影响;采用工程实例验证反演的预报效果,比较前后两次预报相同里程段的波速值。结果显示,S波反演结果具有更好的一致性。     

若尔盖地区地壳三维体波速度结构研究

利用双差层析成像方法反演若尔盖地区三维速度结构,得到该地区的精细三维速度结构和高精度震源位置参数.反演结果显示,研究区速度结构整体呈低速状态,反映出青藏高原内部具有部分熔融物质特性;在青藏高原东北缘地区,强烈的构造变形特征以及低速区蔓延方向印证了青藏高原内部物质向东南方向流溢的科学推测;低速青藏高原板块与相对较硬的若尔...     

A system dynamics model for billion trees tsunami afforestation project of Khyber Pakhtunkhwa in Pakistan:Model application to afforestation activities

As part of the global effort to plant billion trees, an afforestation project is launched in Pakistan in Khyber Pakhtunkhwa(KP) province to conserve existing forests and to increase area under forest cover. The present study is designed to build a Systems' model by incorporating major activities of the Billion Tree Tsunami Afforestation Project(BTTAP) with special focus on afforestation activities to estimate the growth in forest area of KP.Availability of complete dataset was a challenge. To fix the model, the raw data taken from the project office has been utilized. Planning Commission Form 1-Phase I II helped us with additional information.We relied on the data available for one and half period of the project as rest of the data is subject to the completion of the project. Our results show that the project target to enhance area under forest differs from the target to afforest area under the project. The system dynamics' model projection shows that the forest area of KP would be 23.59 million hectares at the end of the BTTA project, thus having an increaseof 3.29% instead of 2% that has been initially proposed. However, the results show that the progress to meet the target in some afforestation classes is slow as compared to other categories. Farm forestry, plantation on communal lands and owners' plantation need special focus of the authority.Deforestation would affect 0.02 million hectares area of the project. The model under study may be used as a reference model that can be replicated to other areas where billion tree campaigns are going on.     

Effect of river plume on phytoplankton community structure in Zhujiang River estuary

To examine the phytoplankton assemblages and the effect of diluted waters on them,a re search cruise was conducted from July 19 to August 7,2015 in the Zhujiang(Pearl) River estuary in the northern South China Sea(21°N-23.5°N,111°E-117°E).Samples were collected from 65 stations including one for time-series sampling.A total of 212 phytoplankton taxa were identified from 61 genera belonging to4 phyla.Among them,122 species identified from 42 genera of Bacillariophyta and 83 species from 15 genera of Pyrrophyta.Chain-forming diatoms dominated the phytoplankton community where Pseudonitzschia delicatissima,Guinardia striata,Thalassionema nitzschioides,and P.pungens comprised about52% of the total abundance.However,higher cell abundances concentrated on both sides of the estuary,because of low salinity and high nutrients brought by diluted water.In addition,Canonical Correspondence Analysis revealed that salinity and dissolved inorganic nitrogen shaped the species composition in the study area.Furthermore,the Jaccard similarity index showed prevailing high similarity in the distribution of species in low-salinity diluted waters,and the Bray-Curtis similarity depicted distinguished grouping for phytoplankton assemblages along the salinity gradient.However,phytoplankton diel vertical cycles showed maximum abundance occurred at 2:00 am,which was mainly contributed by benthic phytoplankton species Pseudo-nitzschia spp.and T.nitzschioides.     

2011年3月云南一次寒潮天气过程分析

2011年3月15日～18日是一次典型的南支槽与强冷空气相结合的天气过程,此次过程对云南省造成了强降温雨雪天气.为了研究此次天气过程的成因以及为今后类似天气过程提供预报思路,利用6h间隔的NECP1°×1°再分析资料、常规观测资料和TBB黑体亮温资料,对此次天气过程进行天气学分析和诊断分析.分析结果表明:500hPa高度上中高纬度呈横槽型,横槽与高原东侧的低槽连接,槽后强劲的西北气流为这次寒潮天气过程带来强冷平流;南支槽的东移并加强使暖湿气流不断向云南境内输送;高低层冷暖气流交汇,低层切变线、地面冷锋的持续作用触发了此次降温雨雪天气.     

2011年3月云南一次寒潮天气过程分析

2011年3月15日～18日是一次典型的南支槽与强冷空气相结合的天气过程,此次过程对云南省造成了强降温雨雪天气.为了研究此次天气过程的成因以及为今后类似天气过程提供预报思路,利用6h间隔的NECP 1°×1°再分析资料、常规观测资料和TBB黑体亮温资料,对此次天气过程进行天气学分析和诊断分析.分析结果表明:500hPa高度上中高纬度呈横槽型,横槽与高原东侧的低槽连接,槽后强劲的西北气流为这次寒潮天气过程带来强冷平流;南支槽的东移并加强使暖湿气流不断向云南境内输送;高低层冷暖气流交汇,低层切变线、地面冷锋的持续作用触发了此次降温雨雪天气.     

桑塔木地区三叠系曲流河三角洲存在证据与沉积特征

为了厘清桑塔木地区三叠系砂体成因类型,指导油气勘探,利用岩心、钻测井、分析化验及高精度三维地震资料,研究碎屑岩的粒度、结构、沉积构造、砂体的空间展布、地震反射特征等.结果表明:三叠系TⅡ油组具有粒度细、分选磨圆好、发育小型交错层理、波状层理及水平层理,呈指状产出,地震剖面上具有前积反射构型,典型相干体地层切片见曲流特征的特点,是典型的曲流河三角洲沉积;同时,研究区曲流河三角洲发育2种亚相6种微相,其中平原亚相发育天然堤、水上分流河道及河漫沼泽微相,前缘亚相发育水下分流河道、河口坝和支流间湾3种微相;区内TⅡ油组以发育北部和西南部2个主要方向的曲流河三角洲为主,其中北部三角洲规模大,平原和前缘亚相较发育,西南部三角洲以前缘亚相为主,平原亚相以分流河道沉积为主,前缘亚相主要发育分流河道和河口坝微相.该三角洲的形成与地形坡度及气候的变化密切相关.     

EVAPOTRANSPIRATION OF LOW-LYING PRAIRIE WETLAND IN MIDDLE REACHES OF HEIHE RIVER IN NORTHWEST CHINA

1 IN T R O D U C T IO NW aterbalance and interactions are foundation to utilizew aterresources rationally in arid inland river basins inC hina (W U etal.,2005).W ateravailability in those ar-eas m ay be the m ain constraint to poverty alleviation,publiche…     

高校非会计专业会计学课程教学改革探析

结合非会计专业新的教学要求和特点，基于对会计学精品课程建设研究，从教学目标定位、理论教材改革、会计实验设计、教学手段改进以及师资队伍建设的角度，对非会计专业的会计学教学改革进行了分析，以促进我国高校非会计专业会计学课程的教改建设。     

大陆地震观测中连续震颤波信号的定位

针对大陆地震观测中的连续震颤波,根据其信号特征和观测特点,在准确识别震颤波信号、提高信噪比、缩小信号范围等原则基础上,参考国际上对间歇式震颤的定位方法,对信号的识别、处理及定位方法和技术进行整合、改进,提出对这类信号采用的定位技术和方法流程,并应用该方法对中国大陆地震观测中几个由台风引发的连续震颤波信号进行定位和效果检验。结果表明,这些技术和方法是可行的,其定位结果合理可信。