日本MW 9.0级大地震前后华北和东北地区现今构造应力作用调整过程与研究意义探讨     

谭成轩  胡秋韵  张鹏  丰成君  秦向辉 《地学前缘》2015,22(1):345-359

为了探讨日本M_W 9.0级大地震前后华北和东北地区现今构造应力作用调整过程与研究意义,对华北和东北地区进行原位现今地应力绝对测量与实时监测、GPS测量,结果表明：日本大地震在山东半岛、华北北部地区和东北地区所诱发同震位移引起的张性效应调整周期分别约为6个月(即调整结束时间大约在2011年9月)、15个月(即调整结束时间大约在2012年6月)和26个月(即调整结束时间大约在2013年5月),张性效应调整周期与同震位移大小成正比。在这种调整过程中,往往表现出区域现今构造应力作用方式和构造应力场转换,并可能伴随重大地质事件(如地震等)的发生。2012年5月28日和29日、6月18日、8月26日及2013年1月11日在唐山及其周围地区分别发生的4.8级、3.2级、4.0级、3.3级和3.0级地震与华北北部地区构造应力作用方式和构造应力场转换有关,而2013年10月31日以来在吉林省松原市发生的地震群应与东北地区构造应力作用方式和构造应力场转换有关,而非一个大地震前的小震群。  相似文献   

Pre-shear effect on liquefaction resistance of a Fujian sand     

《Soil Dynamics and Earthquake Engineering》2015

Pre-shear history has been shown to be a critical factor in the liquefaction resistance of sand. By contrast to prior experimental studies in which triaxial shear tests were used to examine the effects of pre-shear on the liquefaction resistance of sand, hollow cylinder torsional shear tests were used in this study to avoid the influence of the inherent anisotropy that is inevitably produced during the sample preparation process because of gravitational deposition. A series of cyclic undrained shear tests were performed on sand samples that had experienced medium to large pre-shear loading. The test results showed that the liquefaction resistance of sand can be greatly reduced by its pre-shear history, and a pre-shear strain within the range from 0.1% to 5% can cause sand to be more prone to liquefaction. During the cyclic shear tests, the samples that had experienced pre-shear loading exhibited different behaviors when cyclic shear loading started in different directions, i.e., the clockwise direction and the counterclockwise direction. If the cyclic loading started in the identical direction as the pre-shear loading, then the mean effective stress of the sand was almost unchanged during the first half of the loading cycle; if the cyclic loading started in the direction opposite to that of the pre-shear loading, then the mean effective stress decreased significantly during the first half of the loading cycle. However, this anisotropic behavior was only remarkable during the first loading cycle. From the second cycle onward, the speeds of the decrease in the mean effective stresses in the two types of shear tests became similar.  相似文献   

地震和煤矿采动耦合作用下露天矿边坡及采空区稳定性研究     

李海军  魏晓刚  孙琦  卫星  母倩雯 《地震研究》2015,38(1)

为了探讨地震和煤矿采动耦合作用下的露天矿边坡及采空区的稳定性,以辽宁排山楼金矿露天转井工开采为研究对象,基于FLAC3D有限元分析平台,采用强度折减法研究了未进行煤炭开采时和煤矿采动单独作用下露天矿边坡的安全系数,重点探讨了煤矿采动和地震耦合作用下露天矿边坡及采空区应力场、位移场及塑性区的分布规律。结果表明:未经采动时,露天矿边坡的安全系数为1.21,边坡处于稳定状态;煤矿采动后露天矿边坡安全系数降为1.12,仍处于稳定状态,单独的煤矿采动作用不会导致露天矿边坡失稳;在地震和煤矿采动耦合作用下,露天矿边坡坡体内出现了较大的拉应力,采空区顶板出现冒落现象,底板出现底鼓现象;在地震和采动耦合作用下,边坡将出现失稳破坏,破坏形式主要为采动区顶板的大面积冒落和边坡的崩塌。  相似文献   

相邻梁段周期比对伸缩缝处的碰撞响应分析     

武芳文  杨草方  薛成凤  申林  李宇  谢礼立 《地震研究》2015,38(3)

针对相邻两联连续梁桥伸缩缝处的碰撞现象,基于其周期不一致而表现出的动力差异性,进行动力时程分析,采用直接积分法研究了地震作用下相邻联的非同向振动和伸缩缝处的碰撞响应。分析结果表明:不同周期比的相邻梁体,在地震动作用下产生的碰撞响应不同,加速度峰值小持续时间长的地震波对伸缩缝处的碰撞响应较小;碰撞对严重不同向振动的相邻两联(T2/T10.5)的地震响应影响很大,随着相邻两联周期比的增大,碰撞对结构地震反应影响逐渐减小。  相似文献   

DEM modeling of pullout behavior of geogrid reinforced ballast: The effect of particle shape     

《Computers and Geotechnics》2017

The performance of a geogrid reinforced system depends heavily on the properties of interface between the interacting components (i.e., backfill soil and geogrid inclusion). The comprehensive understanding of soil-geogrid interaction requires proper consideration of the true aperture geometry and the discontinuous nature of backfill soil. Based on the calibrated parameters, this paper presents a simulation procedure using PFC3D to reproduce the realistic pull-out behaviors of a triaxial geogrid embedded in various ballast aggregates with diverse particle shapes. The load transfer behaviors across the interacting components have been visualized in terms of the evolution of bond forces along the geogrid and the evolution of contact forces across the particle assembly. Meanwhile, the inherent microscopic changes accounting for the regression of macroscopic strength and the correlation between macro pull-out force and micro anisotropy parameters have been addressed. In addition, the differences in macro performance and the particle responses produced by different shapes of particles are also systematically discussed to justify the significant role of particle geometry. The findings obtained in this study are expected to provide better understanding of soil-geogrid interaction and the improved interlocking caused by irregular ballast geometry.  相似文献   

黑龙江省漠河地区土地覆被与地表温度时空变化特征研究   总被引：1，自引：0，他引：1  

陆妍  喻文兵  郭明  刘伟博 《冰川冻土》2017,39(5):1137-1149

以我国高纬度多年冻土区漠河县城区及郊区862 km²的区域为研究对象,基于RS和GIS技术对该区地表覆被变化和地表温度进行研究。结果表明：地表类型和地表温度反演结果与现场比对结果一致;从1988年到2015年,经过火灾后重建和城镇化发展,建设用地面积增加了11.33 km²;以2015年为例,冬季由于积雪覆盖,有79.02%的区域无植被覆盖,夏季有80.91%的区域为高植被覆盖。冬季地表温度和高程具有高度相关性,高程每升高100 m,地表温度平均升高2.27℃,表明该区地表温度也存在显著的逆温现象。该区城镇热岛效应全年存在,城镇区域地表温度高于全区平均值,夏季最显著,最高温差可达6.37℃。地表温度与NDVI具有明显的负相关关系;不同土地利用类型地表温度由低到高的顺序为水体-林地-草地-裸地-建筑用地。  相似文献   

环太平洋极性超级地幔柱及其成矿响应     

童航寿  田建吉 《铀矿地质》2017,(1):1-8

地幔柱及其成矿系统研究是当前地学领域的热点之一,在我国已取得了较大进展,发表了大量论著。但对环太平洋极性超级地幔柱成矿系统的研究,目前还处于起步阶段。文章在前人研究成果的基础上,从以下几方面作了简要论述:1)地幔柱研究历史的回顾;2)地幔柱类型划分与成矿场;3)常规地幔柱判别标志;4)环太平洋极性超级地幔柱的厘定;5)环太平洋极性超级地幔柱成矿效应;6)华南亚地幔柱与成矿;7)环太平洋极性超级地幔柱的动力学讨论。笔者认为,中-新生代濒太平洋洲际性成矿域及其成矿大爆发,导源于太平洋超级地幔柱对成矿的响应。  相似文献   

美国近期陆地油气钻井业逐步回升的态势分析          下载免费PDF全文

左汝强 《探矿工程》2017,44(7):1-8

自2014年6月国际油价暴跌开始,世界油气市场进入低迷阶段。而当美国二叠纪盆地巨量页岩油藏发现和开发之后,从2016年中期开始,美国陆上油气钻采活动逐渐增加,钻井承包商与钻井公司携钻机蜂拥而至二叠纪盆地和其它油田。这新一轮油气市场可能回复的迹象,进一步促进了钻井设备的更新换代,以工厂化作业为标志的新型先进钻机将供不应求,而大多数老旧机械式钻机则面临淘汰。另一方面,由于这二三年油气市场的低谷,许多高级技术人员和熟练操作人员被裁员,人才大量流失,而新型先进钻机也需要具有专门技能的人员操作,于是近期美国许多公司把保留和培养钻采技术人才放在重要位置,制订和实施了许多培训人才的策略和措施。本文对近期美国陆地油气钻井活动的主要特点和态势进行了分析。  相似文献   

Geochemistry, Geochronology and Lu-Hf Isotopes of Peraluminous Granitic Porphyry from the Walegen Au Deposit, West Qinling Terrane     

GUO Xianqing  YAN Zhen  Jonathan C. AITCHISON  FU Changlei  WANG Zongqi 《《地质学报》英文版》2017,91(6):2024-2040

Walegen Au deposit is closely correlated with granitic intrusions of Triassic age, which are composed of granite and quartz porphyries. Both granite porphyry and quartz porphyry consist of quartz, feldspar and muscovite as primary minerals. Weakly peraluminous granite porphyry(A/CNK=1.10–1.15) is enriched in LREE, depleted in HREE with Nb-Ta-Ti anomalies, and displays subduction-related geochemistry. Quartz porphyry is strongly peraluminous(A/CNK=1.64–2.81) with highly evolved components, characterized by lower TiO_2, REE contents, Mg~#, K/Rb, Nb/Ta, Zr/Hf ratios and higher Rb/Sr ratios than the granite porphyry. REE patterns of quartz porphyry exhibit lanthanide tetrad effect, resulting from mineral fractionation or participation of fluids with enriched F and Cl. LAICP-MS zircon U-Pb dating indicates quartz porphyry formed at 233±3 Ma. The ages of relict zircons from Triassic magmatic rocks match well with the detrital zircons from regional area. In addition, ε_(Hf)(t) values of Triassic magmatic zircons from the granite and quartz porphyries are -14.2 to -9.1(with an exception of +4.1) and -10.8 to -8.6 respectively, indicating a crustal-dominant source. Regionally, numerous Middle Triassic granitoids were previously reported to be formed under the consumption of Paleotethyan Ocean. These facts indicate that the granitic porphyries from Walegen Au deposit may have been formed in the processes of the closing of Paleotethyan Ocean, which could correlate with the arc-related magmatism in the Kunlun orogen to the west and the Qinling orogen to the east.  相似文献   

洞庭湖区与城陵矶水位关联性的临界特征分析   总被引：1，自引：0，他引：1       下载免费PDF全文

孙昭华  李奇  严鑫  罗方冰 《水科学进展》2017,28(4):496-506

采用典型测站观测资料与水力学原理相结合,分析不同情况下城陵矶水位与洞庭湖区水位关联性强弱转化的机理和临界条件以及三峡水库对其影响等问题。理论解析表明,固定流量下,湖区水位与城陵矶水位相关关系应为单调指数函数,受到区间距离、湖槽形态等多因素影响,据此提出和率定了各湖区水位的经验计算模式。利用经验计算模式对实测数据进行延展,构建了各种可能出现的湖区来流和干流水位组合下的湖区水位特征曲线族,发现湖区水位与城陵矶水位之间的关联强度存在无影响区、影响区和决定区等状态区间,通过对临界条件的定义和计算,实现了各状态区间的定量划分,并提出了各状态区间内洞庭湖区水位的估算方法。通过对三峡水库蓄水后湖床冲淤和水文条件变化的影响分析,论证了以上方法和认识在水库蓄水后的适用性。  相似文献