Soil bentonite wall protects foundation from thrust faulting: analyses and experiment

When seismic thrust faults emerge on the ground surface,they are particularly damaging to buildings,bridges and lifelines that lie on the rupture path.To protect a structure founded on a rigid raft,a thick diaphragm-type soil bentonite wall(SBW) is installed in front of and near the foundation,at sufficient depth to intercept the propagating fault rupture.Extensive numerical analyses,verified against reduced–scale(1 g) split box physical model tests,reveal that such a wall,thanks to its high deformability and low shear resistance,"absorbs" the compressive thrust of the fault and forces the rupture to deviate upwards along its length.As a consequence,the foundation is left essentially intact.The effectiveness of SBW is demonstrated to depend on the exact location of the emerging fault and the magnitude of the fault offset.When the latter is large,the unprotected foundation experiences intolerable rigid-body rotation even if the foundation structural distress is not substantial.     

利用Terra和Aqua卫星地表温度探索汶川地震同震热响应

如何从卫星热红外遥感影像中提取出可靠的、能够验证的、与构造活动有关的热信息,是利用热红外信息研究构造现今活动亟待完善的问题之一.从信息提取的角度看,地震前后所对应的物理变化最为强烈,同震热响应可能是利用热信息探索现今构造活动潜在的突破点.本文以MODIS/Terra和MODIS/Aqua两颗卫星的地表温度为基础,探索汶川地震同震热响应.首先,去除了由地形等静态因素和太阳年周期组成的稳定背景;其次,去除大气环流的影响,获得由本地因素产生的原地温度场.最后,在原地温度场中,发现了汶川地震的同震温度响应.经过检验,上述温度响应的空间展布形态与发震断层的活动方式产生的力学效应吻合.从应力变化与温度响应的关系看,本文相当于借助热信息获得了汶川地震同震拉张或卸载区的空间展布情况.     

夏垫断裂带深部构造特征与第四纪活动性讨论

利用重力、浅层地震和高密度电阻率法物探工作成果,由深及浅垂向上“接力拼接”的方式,结合钻探等手段,把夏垫断裂带分解为基岩断裂带和第四纪断裂带2个部分进行研究,结果表明:1)夏垫断裂带的基岩断裂带由主干断裂和次级断裂构成.其北段(马坊-西集一带)较窄,由2条主干断裂构成.其南段(西集-凤河营一带)较宽,由3条主干断裂构成.2)第四纪断裂带是基岩断裂带向上延伸的部分,是断裂带最新活动的直观表现,并受控于基岩断裂带.夏垫第四纪断裂带同样由主干和次级断裂构成,北段(马坊-西集一带)由2条主干断裂和分布于北端尾部次级断裂构成,与基岩断裂带一一对应关系较好.2条主干断裂产状差异较大,最新活动时间均为全新世.而南段(西集-凤河营一带)断裂分布不连续,很难分清主次断裂,同基岩断裂带的对应关系较差,推测为基岩断裂中夏垫断裂的活动.这些主、次级断裂产状均较为陡立,最新活动时间为晚更新世晚期-全新世早期.3)夏垫断裂带内上、下两盘全新世沉积底界垂向累积位错量为1.7 ～4.8m,晚、中、早更新世以来则分别为6 ～ 26m、26 ～ 167m和44 ～ 330m,其中最大累积位错量位于夏垫地区,向南、北逐渐减小.4)以张家湾断裂为界把夏垫断裂带划分为南、北2段.北段第四纪活动性强,中强震及微小地震时有发生,而南段第四纪活动性弱,仅发生微小地震.     

小江断裂带中段和南段井水位变化与形变分析

应用井孔-裂隙、微裂隙(孔隙)水流交换产生的潮汐水位-固体潮的位相差和振幅变化理论,结合井水位变化,分析小江断裂带中段和南段的形变特征.裂隙承压含水层条件下,地震波和构造应力引起的形变能够引起潮汐水位分波位相差和振幅的变化.地震波引起含水层与井孔之间水流交换增大,疏通裂隙而使渗透率增大,震后井水位潮汐分波相位差提前,其后裂隙内沉积物重新堵塞裂隙,渗透率降低,位相差逐渐下降.位相差的长期趋势性变化反映出含水层在构造应力作用下的应变信息.小江断裂带中段和南段形变变化不同.断裂带中段地区,观测井位相差和振幅趋势性下降,表明该区段不仅有走滑特性,并且具有挤压特征.小江断裂带与红河断裂带交会地区观测井振幅和位相差稳定,表明该区域没有受到明显的挤压,形变不明显.     

数字柳州地理空间框架应用推广探索与实践

地理空间框架是数字城市乃至智慧城市建设的重要基础,其应用推广的好坏关系到系统能否长效运行,是重中之重。本文以数字柳州地理空间框架为例,分析应用推广的现状与存在的问题,探索应用推广的模式,总结应用推广的内容与方法,并结合柳州实际情况进行了实践,搭建了教育学区专题应用、存量房价格认证服务平台、人口电子地图管理系统、三维土地供应系统,并与数字化城市管理系统实现了对接,同时在公众网搭建了地理信息公众服务系统。     

数字城市地理空间框架的研究与设计

"数字城市"是城市信息化的重要组成部分,在国民经济和社会发展进程中发挥着重要作用。地理空间数据框架是构建"数字城市"的数据平台,是建设"数字城市"的必要保证。网络地理信息系统(WebGIS)是"数字城市"建造和实践的基础,文中概括了分布式技术下WebGIS的技术特点,提出基于WebGIS构建数字城市地理空间框架,较好地解决了数字城市应用系统的互操作性和分布性问题。     

数字马鞍山3维可视化平台的设计与实现

3维可视化平台是数字城市地理空间框架的重要组成部分,本文介绍了数字马鞍山建设中3维平台的设计与实现思路。从2,3维协同服务的角度设计了3维建设技术路线,并对海量数据传输加载及2,3维联动等关键问题提出了有益的解决方案。为其他城市建设地理空间框架提供借鉴。     

GNSS在线数据处理系统在工程控制网中的应用与分析

介绍目前几个主要的GNSS在线数据处理系统,着重利用其中5个GNSS在线数据处理系统对某工程控制网的观测数据进行多个方案的处理;对处理结果进行对比分析,检验其内符合精度;再利用框架和历元转换理论和方法,将多个系统处理获得的不同ITRF框架下2011即时历元的观测点坐标转换归算到CGCS2000坐标下进行对比,结果表明:GNSS在线数据处理系统完全能够满足工程控制网的数据处理、精度要求以及成果提交等需求。     

Designing thought,technical line and some theoretical issues on geospatial digital framework of China

Based on the developing tendency of present China's basic GIS, this paper discusses the designing idea for scales of 1∶10 000, 1∶50 000, 1∶250 000 and 1∶1 000 000 pyramidlike multi-layer and multi-resolution of the basic GIS. A technical line for the construction of basic GIS of the whole country and various provinces for sustainable development is put forward. And some important theoretical GIS issues touched by the technical process are discussed.     

Assessing image processing techniques for geological mapping: a case study in Eljufra,Libya

Various image processing techniques were experimented with in this study to evaluate their efficiency for geological mapping in the Eljufra area of northwest Libya. Remote sensing data including multi-spectral optical Landsat Enhanced Thematic Mapper (ETM+), Synthetic Aperture Radar (ERS-2 SAR) and Digital Elevation Models (DEMs) extracted from the Shuttle Radar Topography Mission (SRTM) data were used to trace different lithological units as well as extracting geological lineaments in the study area. The study area is located in an arid environment mostly devoid of any vegetation. Most lithological and structural units are distinguishable based on their topographic form and spectral properties. Fusion of ETM+ and ERS-2 images was experimented with to further identify lithological units. Shaded relief techniques were implemented to enhance terrain perspective views and to extract geological lineaments. The results discriminated different rock units and modified formation boundaries and revealed new geological lineaments. Nine rock units were identified and plotted in the new geological map defined by the new boundaries. The dominant lineaments tend to run in the NNW-SSE and NNE-SSW directions. Analysis and interpretation of the lineaments provided information about the tectonic evolution of the study area.