Research on the Relationship between Active Faults and Earthquakes in the Junction Area of the China North-South Seismic Belt and Central Orogenic Belt Based on GIS

Research on the relationship between faults and seismicity in the junction area of China's north-south seismic belt and central orogenic belt based on the Geography Information System (GIS) has been done.For each of the 16 faults in this area,we build a 25km buffer zone and use overlay analysis to investigate the seismicity and its characteristics on each fault.The results unveil the main seismic faults as follows:the western segment of the northern-edge of the west Qinling fault,the southwestern segment of the Lixian-Luojiabao fault,the southeastern segment of the Lintan-Dangchang fault,the southwestern segment of the Wenxian fault,the Huya fault,and the Xueshan fault.The most active faults are the Huya and Xueshan faults,then the Tazang fault,the Lixian-Luojiabao fault and the northern piedmont of the Guanggaishan-Dieshan fault.The research zone can be divided into four areas according to focal depth,which gets deeper from north to south.The profile of focal depth indicates the geometry and mechanical property of faults,and further reveals the movement model of eastward extrusion of the Tibetan plateau and southeastward escape of masses,thus providing basis for the protection against earthquakes and hazard mitigation in this area.     

Current developments of research on permafrost engineering and cold region environment: a report of the 8th International Symposium on Permafrost Engineering

The Eighth International Symposium on Permafrost Engineering was held in Xi’an,China,October 2009.The major topics discussed in the symposium included:permafrost engineering (involving design,construction and evaluation);mitigation of frost hazards in the regions affected by seasonally frozen ground;properties of frozen soils,model development and their applications;frost hazards and periglacial environments in mountain and plateau regions;climatic,environmental and cryospheric changes;and permafrost hydrology,cold regions water resources and land uses.The papers submitted to the symposium and lectures during the meeting represented some new developments of research on cold region engineering and environment.Here we summarized the works of the symposium in topics including:Permafrost engineering;General geocryology;Properties of frozen soils:model development and their applications;And climatic,environmental and cryospheric changes.During the symposium,the attendees pointed out that future studies should pay more attention to theoretical study and engineering mechanism study,and also on interaction between climate change and cold region environments and their engineering affects.     

基于室内模拟实验的软土固结沉降的分形几何

为了能够比较准确、简便地计算及预测软土的沉降,在Terzaghi一维固结理论的基础上,结合分形几何理论对软土的沉降计算进行了探讨和研究。首先通过室内模拟实验,获得了不同固结时期试样的孔隙比e、沉降量以及扫描电镜照片（SEM图片）;然后利用WD-5软件对SEM图片进行处理,并计算得到孔隙分布的分数维D_f;最后建立起e与D_f的函数关系,再结合Terzaghi一维固结理论建立了D_f与固结度、沉降量的关系方程并计算得到相应的固结度及沉降量。经分析得出：Df随着沉降量的增加而减小;软土在固结沉降过程中在42.33 h处有一个明显的拐点;利用Df建立的固结沉降模型计算的结果与试验实测的结果基本吻合。     

永年地震台伸缩仪EW向张性异常分析

针对河北永年地震台伸缩仪EW分量2015年5月11日起出现的加速拉张变化,从仪器工作状态、洞室环境、气象条件和外界环境干扰等方面,进行调查分析。利用3种荷载模型计算道路施工荷载变化可能引起的应变变化量,并结合其他形变测项变化特征进行论证,认为永年伸缩仪张性变化是区域应力场调整的结果。     

Using a global reference sample set and a cropland map for area estimation in China

A technically transparent and freely available reference sample set for validation of global land cover mapping was recently established to assess the accuracies of land cover maps with multiple resolutions. This sample set can be used to estimate areas because of its equal-area hexagon-based sampling design. The capabilities of these sample set-based area estimates for cropland were investigated in this paper. A 30-m cropland map for China was consolidated using three thematic maps (cropland, forest and wetland maps) to reduce confusion between cropland and forest/wetland. We compared three area estimation methods using the sample set and the 30 m cropland map. The methods investigated were: (1) pixel counting from a complete coverage map, (2) direct estimation from reference samples, and (3) model-assisted estimation combining the map with samples. Our results indicated that all three methods produced generally consistent estimates which agreed with cropland area measured from an independent national land use dataset. Areas estimated from the reference sample set were less biased by comparing with a National Land Use Dataset of China (NLUD-C). This study indicates that the reference sample set can be used as an alternative source to estimate areas over large regions.     

A simplified design method for metallic dampers used in the transverse direction of cable-stayed bridges

The aseismic design of cable-stayed bridges in the transverse direction with newly proposed metallic dampers that can accommodate both longitudinal and transverse movement of the deck has recently been considered. This work focuses on developing a simplified method to design an appropriate metallic damper. The seismic performance of cablestayed bridges with different damper stiffness, main span lengths, tower shapes and types of deck in the transverse direction are investigated. The transverse displacement of the deck of a cable-stayed bridge increases significantly with the increment of the damper stiffness, which proves that the design of the damper stiffness is crucial. A simplified model considering the damper stiffness, cable system and tower in the transverse direction is developed to evaluate the period and lateral displacement of a complicated cable-stayed bridge. Based on the simplified model, a design method is proposed and assessed using two cable-stayed bridges as examples. The results show that metallic dampers can be designed with high efficiency, and the optimal ductility of the damper can be selected.     

Study of seismic behavior of PHC piles with partial normal-strength deformed bars

Nine PHC piles with partial normal-strength deformed bars were prepared in present study, and cyclic loading tests were implemented to evaluate these piles’ seismic performance. The influence of the axial compression ratio and the amount of normal-strength deformed bars on failure modes, crack patterns, strength, stiffness, and ductility were examined. The test findings indicate that the change of axial compression ratio has a noticeable influence on the failure mode of PHC piles. A larger axial compression ratio results in a higher cracking bending resistance, ultimate bending resistance, and initial stiffness, but the propagation heights of flexural cracks decrease as the axial compression ratio increases. Furthermore, increasing the amount of normal-strength deformed bars causes a slight decrease in ductility. Finally, a calculation formula was proposed to predict the flexural capacity of PHC piles with partial normal-strength deformed bars.     

东南亚红土镍矿床地质地球化学特征及成因探讨——以印尼苏拉威西岛Kolonodale矿床为例

Kolonodale矿床是东南亚红土镍矿带上一处典型矿床,位于印度尼西亚苏拉威西岛东部。矿床产自富镁超基性岩红土风化壳,矿化剖面自上而下出现红土层→腐岩层→基岩层垂向分带。红土镍矿石产在红土剖面上部,载镍矿物是铁质氧化物。硅镁镍矿石产在红土剖面中下部,载镍矿物为镍蛇纹石、镍滑石等含水层状硅酸盐矿物。地球化学分析显示,沿矿化剖面元素地球化学分异非常显著,Ni次生富集效应明显。超基性岩红土化过程的元素地球化学行为具有多样性,Fe、Al、Ti、Cr属残留富集组分,Si、Mg属淋滤缺失组分,Mn、Ca、Co、Ni属次生富集组分。通过典型矿床对比,Kolonodale矿床属原地自生硅酸盐型红土镍矿床,其发育受地质背景和地表环境条件的综合制约。富镁超基性岩、良好的构造组合、稳定的大地构造环境、湿热热带雨林气候、有利地形地貌等均是成矿有利条件。综合分析认为,Kolonodale矿床的成矿过程可划分为腐岩化、红土化和次生富集3个成矿阶段。     

The Eocene corundum-bearing rocks in the Gangdese arc,south Tibet:Implications for tectonic evolution of the Himalayan orogen

The genesis of Liangguo corundum deposit in the southern Gangdese magmatic arc, east-central Himalaya, remains unknown. The present study shows that the corundum-bearing rocks occur as lenses with variable sizes in the Eocene gabbro that intruded into marble. These corundum-bearing rocks have highly variable mineral assemblage and mode. The corundum-rich rocks are characterized by containing abundant corundum, and minor spinel, ilmenite and magnetite, whereas the corundum-poor and corundum-free rocks have variable contents of spinel, plagioclase, sillimanite, cordierite, ilmenite and magnetite. The host gabbro shows variable degrees of hydration and carbonization. The corundum grains are mostly black, and rarely blue, and have minor Fe O and TiO_2. The spinel is hercynite, with high Fe O and low Mg O contents. The corundum-bearing rocks have variable but high Al_2O_3, FeO and TiO_2, and low SiO_2 contents. Inherited magmatic and altered zircons of the corundum-bearing rocks have similar U e Pb ages(~47 Ma) to the magmatic zircons of the host gabbro, indicating corundum-bearing rock formation immediately after the gabbro intrusion. We considered that emplacement of gabbro induced the contact metamorphism of the country-rock marble and the formation of silica-poor fluid. The channeled infiltration of generated fluid in turn resulted in the hydrothermal metasomatism of the gabbro, which characterized by considerable loss of Si from the gabbro and strong residual enrichment of Al. The metasomatic alteration probably formed under Pe T conditions of ~2.2 -2.8 kbar and ~650 -700℃. We speculate that SiO_2, CaO and Na_2O were mobile, and Al_2O_3, FeO, TiO_2 and high field strength elements remained immobile during the metasomatic process of the gabbro. The Liangguo corundum deposit, together with metamorphic corundum deposits in Central and Southeast Asia, were related to the Cenozoic Himalayan orogeny, and therefore are plate tectonic indicators.     

基于倾斜摄影地表模型的三维地质填图软件关键技术与应用前景

讨论了基于倾斜摄影测量所构建的三维地表模型进行三维地质填图与三维地质建模软件的设计理念、开发环境、软件架构、关键技术、实现现状与应用前景。倾斜摄影影像经处理建模后构建的三维地表模型通常以OSGB格式保存,因此基于倾斜摄影成果的三维地质填图软件最好基于能直接读取、显示OSGB格式数据的OSG开源库,推荐VS2015+QT+OSG开发环境。该类软件的关键技术包括以Proj4为核心的坐标转换系统、地层界线的拾取与半自动追踪技术、基于反距离衰减函数的地层界面防穿透高程调节技术、切制地质剖面并由剖面修改地层界面的二三维联动编辑与修改地层界面的技术、在露头剖面上采集地层界线构建露头地层柱状图的技术。该软件的应用前景包括野外区域地质调查、煤田和油田等行业的野外地质填图,以及滑坡和泥石流崩塌等地质灾害危险区域的圈定。