Indicator geostatistics for reconstructing Baton Rouge aquifer-fault hydrostratigraphy, Louisiana, USA

The complex siliciclastic aquifer system underneath the Baton Rouge area, Louisiana (USA), is fluvial in origin and is characterized by strongly binary heterogeneity of sand units and mudstones as pervious and impervious hydrofacies. The east–west trending Baton Rouge fault and Denham Springs-Scotlandville fault cut across East Baton Rouge Parish and play an important role in groundwater flow and aquifer salinization. This study reconstructs the Baton Rouge aquifer-fault system architecture for a Miocene-Pliocene depth interval that consists of the 1,200-foot sand to the 2,000-foot sand. The results show the spatial extent of sand units, their interconnections, and flow paths within each sand unit. The regional-scale formation dip, the sand unit offset on the faults, and the volumetric spatial extent of individual sand units are quantified. The study reveals the complexity of the Baton Rouge aquifer-fault system where the sand deposition is non-uniform, different sand units are interconnected, the sand unit displacement on the faults is significant, and the spatial distribution of flow pathways through the faults is sporadic. The identified locations of flow pathways through the Baton Rouge fault provide useful information on possible windows for saltwater intrusion from the south.     

阿家岭隧道穿越既有铁路线综合施工技术

阿家岭隧道穿越既有铁路线,通过采取洞室管棚预支护、沉降反馈开挖法、加强初期支护、监控量测技术、管棚变形监测等综合治理技术,有效地控制了既有铁路的线路沉降量,保证了顺利穿越既有铁路线。该综合技术根据隧道施工条件,突破常规施工方法和工艺,为施工类似隧道提供了参考。     

Modeling complex aquifer systems: a case study in Baton Rouge,Louisiana (USA)

Hydrogeology Journal - This study targets two challenges in groundwater model development: grid generation and model calibration for aquifer systems that are fluvial in origin. Realistic...     

地表不具备钻探条件下的盾构机通过空洞地段施工技术

本区间因隧道下穿南航酒店和火车站地中海商场及停车场,大部分区域无法实施钻探。而由周边地质资料及施工所反映的情况推测,该区域有存在空洞的可能。未探明的空洞可能对盾构机掘进造成不利影响,如盾构机栽头、地层塌陷等。因此,在盾构机通过未探明区域前必须进行探测和预处理,以指导盾构机掘进。     

Trace element remobilization following the resuspension of sediments under controlled redox conditions: City Park Lake,Baton Rouge,LA

The sediments of City Park Lake (Baton Rouge, Louisiana, USA) are characterized by Pb concentrations that exceed the corresponding National Oceanic and Atmospheric Administration probable effect level by more than a factor of two and concentrations of As, Cd, Cu, Ni and Zn that exceed the corresponding threshold effect levels. The sediments of the lake are likely to be dredged because of concern over shoaling of the lake. There is concern that exposing these sediments to an oxidizing environment could mobilize toxic metal(loid)s that are effectively sequestered under reducing conditions. To address this concern, mixtures of sediments collected from seven locations in City Park Lake were incubated in microcosms under controlled oxidizing and reducing conditions. The slurries were sampled at time intervals over a period of nearly 750 h, and the dissolved Fe, Mn and trace metal concentrations determined. Eh and pH were negatively correlated, with Eh declining by 600 mV per unit increase in pH. Of the toxic metals, only the concentration of Cu was positively correlated with Eh, apparently because of the sequestration of Cu as a very insoluble sulfide precipitate under low Eh conditions. Precipitation of the other metals as sulfides was evidently insignificant because of the low S content of the sediments. Concentrations of the remaining potentially toxic metals were negatively correlated with Eh, apparently because of their sequestration as oxides and/or adsorption to Fe oxides or oxy-hydroxides. Concentrations of Ca, Mg, and Sr were positively correlated with Eh, presumably because of their sequestration in carbonate precipitates under low Eh/high pH conditions.     

高速铁路浅埋大跨度隧道下穿公路施工安全性分析

成都至贵阳客运专线南厂沟浅埋大跨度隧道下穿公路,重载车辆繁多,对隧道施工安全及道路行车安全造成威胁。采用FLAC3D软件分别对无行车条件下和行车荷载作用下施工过程进行了数值模拟,对比分析了两种工况下的受力及变形,结果表明,行车荷载对该隧道施工影响较小。下穿施工过程及监测数据分析表明,南厂沟隧道下穿公路数值模拟是合理的,为顺利施工提供了有益指导。     

南水北调中线一期工程下穿京九铁路隧道工程设计

文章详细介绍了下穿隧道的明挖段、暗挖段的工程措施,对京九铁路路基、轨道的加固措施以及监控量测的方法.为日后类似工程提供一定的设计、施工经验.     

水平定向钻岩石层穿越套管安装工艺

在水平定向钻穿越长距离、复杂地质条件施工中,为保证穿越导向孔钻进工程的顺利进行,避免或减少钻杆在传递推力时在钻孔内产生“蛇行”弯曲、不能有效传递推力、钻进方向不易控制等不利因素,通常采用在钻机侧沿钻进方向的钻杆上加装部分套管技术。本文详细阐述了水平定向钻岩石层穿越套管安装的施工流程、安装技术措施,同时对套管的钻进、润滑、回抽等环节进行了分析,并对套管施工过程中安全注意事项提出了几点建议。     

认真贯彻十六大精神思想政治工作要与时俱进

党的十六大是我们党在新世纪召开的第一次盛会,将对我们党和国家事业发展产生重大而深远的影响。深入学习贯彻党的十六大精神,是全党当前和今后一个时期的首要政治任务。江泽民同志在十六大报告中指出,要加强和改进党的建设。而党的建设最根本的是思想政治建设。时至当今,科技进步日新月异,新生事物层出不穷,人们思想纷繁复杂,思想政治工作面临着诸多新情况、新难     

Blast-resistant Analysis for a Tunnel Passing Beneath Taipei Shongsan Airport–a Parametric Study

This paper covers the blast-resistant analysis for a tunnel passing beneath Taipei Shongsan airport. It briefly discusses the overall analysis process to obtain the maximum lining thrust caused by a bomb explosion for use in the structural lining design. Because there have not been any established common standards or practices governing the design of such a structure, a series of parametric studies have been carried out in order to evaluate the significance and sensitivity of several parameters on the lining thrust. The parameters evaluated are: intensity of blast loading, size of crater, dynamic undrained shear strength, dynamic Young’s modulus, and soil-damping ratio. It was concluded that a designer should adopt dynamic soil parameters, obtained from good ground investigation and soil testing, as favorable dynamic soil properties can result in a more economical analysis. For parameters (e.g. bomb type) that are beyond the control of the designer, an additional protective layer over the tunnel structure may be considered in order to minimize the impact of the explosion, instead of designing a more costly rigid structure.