A case study of damages of the Kandla Port and Customs Office tower supported on a mat–pile foundation in liquefied soils under the 2001 Bhuj earthquake

A case study is presented of the interaction between the bending due to laterally spreading forces and axial-load induced settlement on the piled foundations of the Kandla Port and Customs Tower located in Kandla Port, India, during the 2001 Bhuj earthquake. The 22 m tall tower had an eccentric mass at the roof and was supported on a piled-raft foundation that considerably tilted away as was observed in the aftermath of the earthquake. The soil at the site consists of 10 m of clay overlaid by a 12 m deep sandy soil layer. Post-earthquake investigation revealed the following: (a) liquefaction of the deep sandy soil strata below the clay layer; (b) settlement of the ground in the vicinity of the building; (c) lateral spreading of the nearby ground towards the sea front. The foundation of the tower consists of 0.5 m thick concrete mat and 32 piles. The piles are 18 m long and therefore passes through 10 m of clayey soil and rested on liquefiable soils. Conventional analysis of a single pile or a pile group, without considering the raft foundation would predict a severe tilting and/or settlement of the tower eventually leading to a complete collapse. It has been concluded that the foundation mat over the non-liquefied crust shared a considerable amount of load of the superstructure and resisted the complete collapse of the building.     

有冰海域溢油运动数值模型研究

提出了寒冷海域溢油运动短期数值模型,其中海冰运动预报模型针对不同海冰密集度的本构关系亦不同,在近岸及密集度较高的冰带采用基于连续介质理论的粘塑性本构关系;在冰边缘密集度较低的冰带采用基于离散介质理论的碰撞本构关系计算冰内力;溢油运动预报模型包括连续冰盖及高、中、低密集度冰场中溢油的漂移和扩展过程的预报.模拟计算结果表明模型的建立是合理的.该模型可用于事故溢油预报,为溢油的围收治理提供依据.     

Relationship between Formation of Zhongyebei Basin and Spreading of Southwest Subbasin, South China Sea

The Zhongyebei (中业北) basin (ZYBB) is an NE-striking,narrow and small sedimentary basin superimposing the southern 1/2 segment of the proposed spreading axes of the SW subbasin of the South China Sea (SCS).More than 4 500 m strata were identified in the Zhongyebei basin,including the Paleogene lower structure layer and the Neogene upper structure layer.The SW subbasin of the South China Sea has been regarded as an oceanic basin opened by seafloor spreading,as evidenced by the fiat and deep (＞ 4 000 m mostly) seafloor with linear magnetic anomalies,and by the shallow Moho depth of ＜ 12 km as estimated from gravity modeling.The classic model of seafloor spreading predicts that sediments on the oceanic crust are younger and thinner towards the spreading axes.But in the southwestern segment of the SW subbasin,contradictions appear.Firstly,the thick sedimentation in the ZYBB is along the proposed spreading axes.Secondly,the sediments are thinner (500-1 500 m) and younger away from the proposed spreading axes.Thirdly,geological elements of the two sides of spreading axes develop asymmetrically in the southwestern SW subbasin.Two models,the early opening model and the limited modeling model,are suggested for resolving this paradox.The former suggests that the opening of the SW subbasin was in Late Eocene and earlier than the oldest sediment in the ZYBB.The latter proposes that the opening of the SW subbasin was limited to its northeastern portion,and did not extend to the southwest portion.The ZYBB is a rift basin survived from the spreading but subjected to severe syn-spreading magmatic disturbance.The SW subbasin and the ZYBB of the SCS provide a unique opportunity for studying the structural evolution and dynamic mechanism at the tip of a propagating seafloor spreading.Both models have unresolved questions,and further studies are needed.     

Supercontinental cyclicity in the Earth’s evolution

The Earth’s evolution is determined by supercontinental cyclicity with a period of 400 Ma. A supercycle consists of a supercontinental proper and an inter-supercontinental stage, each of which includes two phases, respectively: integration-destruction and fragmentation-convergence. The worldwide analysis of geologic-historic and isotope-geochronologic data supports the existence of such cyclicity. In all, ten supercontinental cycles of supercontinents have been identified; in this case, the most ancient proto-supercontinent was recognized tentatively, Supercontinents identified previously by other researchers fit into this cyclicity. An association between magmatism from mantle plumes and certain phases of supercontinental cyclicity was revealed. Amalgamation and breakup of supercontinents occurred against the background of disymmetry of the Northern and Southern hemispheres of the Earth, which changed its polarity between the cycles.     

均匀倾斜层状地层中地震波球面扩散补偿方法研究

在分析地层深度、炮检距以及地层倾角变化对球面扩散补偿因子影响的基础上,总结了不同因素对补偿因子影响的趋势,以及资料处理中常规球面扩散补偿方法的应用条件．实际应用效果表明,该方法能更加合理的保证不同深度地震信息能量的均衡程度,提高资料的可信度。     

Masirah—the other Oman ophiolite:A better analogue for mid-ocean ridge processes?

Oman has two ophiolites – the better known late Cretaceous northern Oman (or Semail) ophiolite and the lesser known and smaller, Jurassic Masirah ophiolite located on the eastern coast of the country adjacent to the Indian Ocean. A number of geological, geochronological and geochemical lines of evidence strongly suggest that the northern Oman ophiolite did not form at a mid-ocean ridge but rather in a supra-subduction zone setting by fast spreading during subduction initiation. In contrast the Masirah ophiolite is structurally part of a series of ophiolite nappes which are rooted in the Indian Ocean floor. There are significant geochemical differences between the Masirah and northern Oman ophiolites and none of the supra-subduction features typical of the northern Oman ophiolite are found at Masirah. Geochemically Masirah is MORB, although in detail it contains both enriched and depleted MORB reflecting a complex source for the lavas and dykes. The enrichment of this source predates the formation of the ophiolite. The condensed crustal section on Masirah (ca. 2 km) contains a very thin gabbro sequence and is thought to reflect its genesis from a cool mantle source associated with the early stages of sea-floor spreading during the early separation of eastern and western Gondwana. These data suggest that the Masirah ophiolite is a suitable analogue for an ophiolite created at a mid-ocean ridge, whereas the northern Oman ophiolite is not. The stratigraphic history of the Masirah ophiolite shows that it remained a part of the oceanic crust for ca. 80 Ma. The chemical variability and enrichment of the Masirah lavas is similar to that found elsewhere in Indian Ocean basalts and may simply reflect a similar provenance rather than a feature fundamental to the formation of the ophiolite.     

Dating the Tectonic Deformation since the Middle Triassic for the Tongnanba Anticline in the Northeastern Sichuan Basin and its Geological ImplicationsEI北大核心CSCD

Tongnanba anticline lies in the northeastern Sichuan Basin and experienced multi-stages tectonic compression and superimposition since the Middle Triassic. Its formation and evolution process are chiefly controlled by the squeezing and thrusting from the Micangshan structure belt from NW to SE and subjected to the tectonic superimposition from the Dabashan structure belt from NE to SW. Therefore, to confine the timing of Tongnanba anticline multi-stages deformation is of great effectiveness to constrain the timing of Micangshan intra-continental deformation since the Middle Triassic, and also provides significant indications to the regional tectonic time-space sequence and Micangshan basement-involved thrusting characteristics. In this paper, the anticline's south limb rotating growth strata within the Middle-Upper Jurassic, based on interpretation of two geological section, is featured, indicating that the folding of the strata started around the late Middle Jurassic-Early Late Jurassic and together with the interpretation of long seismic profile, we believe that basement-involved wedge-thrusting structure style is developed in Micangshan structure belt and the basin-ward movement of the displacement of the wedge tip along the Pre-sinian detachment layer results in the formation of the NE structure of Tongnanba anticline. Apatite fission track thermal simulation indicates that Tongnanba anticline started experiencing rapid uplifting and denudation in the early Late Cretaceous (95-90 Ma) and the Middle-Late Cenozoic (about 24 Ma) with uplift speed 0.06-0.085 mm/a and around 0.133 mm/a respectively. Through the summary of regional historical low temperature thermochronology data, geographical partition based tectonic time-space sequence is established, suggesting that northeastern Sichuan Basin experienced N-S basin-ward tectonic spreading from Micangshan structure belt and NE-SW tectonic super imposition from Dabashan structure belt during the Middle-Late Jurassic, Cretaceous and Eocene-Miocene respectively. © 2017, Science Press. All right reserved.     

交通拥堵与预警信息交互传播动力学分析

城市交通拥堵问题已经成为当今世界许多城市发展过程中面临的一个严峻问题。针对这一问题,全空间信息系统通过对复杂、动态的交通拥堵过程进行多粒度抽象、多尺度建模和多层次综合分析,为解决城市交通拥堵提供了新的途径。当城市交通发生严重堵塞时,通常伴随着“道路拥堵”预警信息传播,用以影响人类的出行活动,从而在一定程度上影响交通拥堵传播。为了深入分析城市交通网络拥堵的动态演进过程,本文建立了交通拥堵传播的改进易感-感染-易感（susceptible-in fected-susceptible,SIS）的病毒传播模型,利用状态转移概率方法,基于多层复杂网络分析交通拥堵和预警信息交互传播的动力学行为特征,揭示预警信息传播对交通拥堵传播的影响。该方法不仅能够描述基于交通流传播特点的拥堵传播过程,而且能够描述交通网络中的预警信息传播过程。数字仿真实验表明,交通拥堵的传播过程与交通网络中的预警信息传播动力学之间存在关联关系。     

唐古拉山东段莫云地区二叠纪玄武岩地球化学特征及源区性质

在青藏高原腹地,二叠纪火山岩分布于唐古拉山东段,古地理上位于北羌塘盆地东缘。对唐古拉山东段莫云地区中二叠世栖霞期尕笛考组火山岩的主量元素、微量元素和Sr-Nd同位素进行了分析。岩相学和地球化学指标显示二叠纪火山岩为玄武岩,该套岩石低SiO2、MgO、K2O和Mg#值(0.39～0.48),富Na2O、TFeO、TiO2、P2O5含量,富集LREE和高场强元素(Nb、Ta、Zr、Hf、P、Ti),(La/Yb)N=14.89～23.23,(Gd/Yb)N=2.30～3.58,Eu异常不明显(δEu=0.76～0.99),具有明显的Th正异常和K、Sr负异常,显示与板内碱性玄武岩相似的地球化学特征;同位素组成以低(87Sr/86Sr)i(0.7033～0.7039)、高εNd(t)(+4.2,t=271Ma)为特点,反映岩浆源区既有亏损地幔源(DMM)又有富集地幔源(EMⅠ)的双重属性。岩浆起源可能与地幔柱诱导的软流圈上涌导致含石榴子石橄榄岩的岩石圈地幔部分熔融有关。莫云玄武岩形成于板内伸展环境(初始裂谷),具有主动裂谷作用性质。     

单桩场地液化土横向流动的数值试验分析

强震中,液化土体在重力作用下往往发生水平扩展流动,对桩基础造成了严重破坏,因此有关液化土体流动对桩的影响及其之间的动力相互作用,一直是岩土工程领域研究的热点。通过模拟振动台实验,将这一过程简化为三维的单桩模型进行计算。经过对某一固定流速土体流动的计算,分析得到液化土横向流动中自身的孔隙水压力、变形以及对桩的内力和位移的影响规律。