一种深埋隧道地震响应计算方法

本文通过考虑松动圈围岩强度降低、松动破裂形成的垫层效应以及地震波的绕流效应,提出使用松动圈折减系数R来计算隧道的地震响应.在衬砌结构随地层运动内力理论解基础上,以S波为例,推导了考虑松动圈减震作用的计算方法.运用有限差分软件FLAC3D中的动力模块对隧道松动圈减震问题进行了数值模拟,并与衬砌结构随地层运动内力理论解及建议的松动圈折减系数法进行对比.结果表明,在充分考虑松动圈存在的情况下,使用松动圈折减系数法计算出来的结果与数值模拟结果较为吻合(最大弯矩误差值为8.28％,最大剪力误差值为10.68％),较衬砌随地层运动理论解法更为精确(最大弯矩误差值为62.13％,最大剪力误差值为50.49％).该方法计算思路和概念清晰,计算公式简洁明了,计算量较小,便于实际应用.     

Parametric studies on confinement of radionuclides in the excavated damaged zone due to bentonite type and temperature change

A parametric study is presented in this paper in order to examine the potential of the extruding bentonite into a fracture in the EDZ to confine radionuclides. Radionuclide migration of cesium and neptunium were studied at elevated temperatures and for a sodium- and calcium-type bentonite. Parameter values were obtained based on empirical studies for hydraulic conductivity, molecular diffusion, and sorption. Results indicate extrusion speed is affected by temperature changes. Elevated temperatures also affect radionuclide migration. For Cs, migration is enhanced due to decreasing sorption, while Np migration is inhibited due to increasing sorption. The potential to confine radionuclides is favorable, and the choice of bentonite does not seem to affect radionuclide confinement in the extruding region.     

Evaluating hydro-mechanical interactions of adjacent clay-based sealing materials

Canada’s Nuclear Waste Management Organization (NWMO) is investigating various geological isolation concepts for Canada’s used reactor fuel (NWMO, 2005). These options are all based on the concept of multiple barriers that include Highly Compacted Bentonite (HCB), Dense Backfill (DBF), Light Backfill (LBF), and Gap Fill (GF). The hydraulic, mechanical, and other characteristics of these clay-based sealing materials have been examined previously, but typically in relative isolation (e.g., Dixon, 1999, Blatz, 2000, Siemens, 2006, Stroes-Gascoyne et al., 2006, Baumgartner et al., 2007). Information on how these clay-based sealing materials interact with each other is needed to understand the evolution and performance of the overall sealing system.A total of twenty-three (23) tests that examine the physical interaction of physically dissimilar clay-based sealing materials were installed and monitored at Atomic Energy of Canada Limited’s (AECL) geotechnical laboratory. This paper describes the process of water uptake, interaction between the components installed, and the role of groundwater salinity on water uptake as interpreted from these tests.     

从汶川和芦山地震浅析四川地震次生地质灾害的特点及减灾对策

汶川和芦山地震后四川地震次生灾害频繁发生,以崩塌、滑坡、泥石流和堰塞湖最为常见,主要分布在川西高原、川西南山地的深切河谷地区以及四川地区周围山地.这些次生灾害以活动断裂为地质构造基础,以地表大量松散固体为物质来源,以强烈频繁的余震、坡面流水和暴雨洪水为动力条件,由此形成巨大的灾害链,造成大量人员伤亡和经济损失,其严重后果甚至极大地影响了抗震救灾工作的顺利开展.对于四川地震次生灾害的防治要加强监控,建立预警机制,开展风险评估,因害设防,分层防御.     

Towards dating Quaternary sediments using the quartz Violet Stimulated Luminescence (VSL) signal

Quartz optically stimulated luminescence (OSL) dating is widely used to determine the time of deposition and burial of Late Quaternary sediments. Application of the method is usually limited to the past 150,000 years due to early saturation of the OSL signal. Here we explore the potential to date Quaternary sediments using the violet (402 nm) stimulated luminescence (VSL) signal of quartz. We develop and test a new post-blue VSL single aliquot regenerative dose dating protocol, and demonstrate that the VSL signal originates from a deep trap at about 1.9 eV with a thermal lifetime of 10¹¹ years at 10 °C, and that this trap is bleachable by sunlight. The VSL signal grows with dose to ∼6400 Gy, a factor ∼20 higher than the conventional quartz OSL signal, and with the proposed protocol we recover a known dose of 1000 Gy in three out of four samples. The potential of the VSL protocol for dating Quaternary sediments is highlighted by its successful application to a suite of geological samples ranging in age between 13 and 330 ka. Based on our investigations, we propose that the VSL protocol has the potential to extend the quartz dating range to cover the full Quaternary.     

GIS,multi‐criteria and multi‐factor spatial analysis for the probability assessment of the existence of illegal landfills

This work deals with the identification of potentially contaminated areas using remote sensing, geographic information systems (GIS) and multi‐criteria spatial analysis. The identification of unknown illegal landfills is a crucial environmental problem in all developed and developing countries, where a large number of illegal waste deposits exist as a result of fast, and relatively unregulated, industrial growth over the past century. The criteria used to perform the spatial analysis are here selected by considering the characteristics which are ‘desirable’ for an illegal waste disposal site, chiefly related to the existence of roads for easy access and to a low population density which facilitates unnoticed dumping of illegal waste materials. A large dataset describing known legal and illegal landfills and the context of their location (population, road network, etc.) was used to perform a spatial statistical analysis to select factors and criteria allowing for the identification of the known waste deposits. The final result is a map describing the likelihood of an illegal waste deposit to be located at any arbitrary location. Such a probability map is then used together with remote sensing techniques to narrow down the set of possibly contaminated sites (Silvestri and Omri, 2008 Silvestri, S. and Omri, M. 2008. A method for the remote sensing identification of uncontrolled landfills: formulation and validation.. International Journal of Remote Sensing, 29(4): 975–989. [Taylor & Francis Online] , [Google Scholar]), which are candidates for further analyses and field investigations. The importance of the integration of GIS and remote sensing is highlighted and represents a key instrument for environmental management and for the spatially‐distributed characterization of possible uncontrolled landfill sites.     

Modelling of the hydro-mechanical response of sedimentary rocks of southern Ontario to past glaciations

Glaciation is considered as one of the main natural processes that can have a significant impact on the long term performance of a deep geological nuclear waste repository (DGR) located in the Northern Hemisphere. The northern part of the American continent has been subjected to a series of strong glaciation and deglaciation events over the past million years. The last glacial cycle in the Northern Hemisphere started approximately 110,000 year ago. During that cycle, southern Ontario was buried under a continental ice sheet, with a maximum thickness of up to 3000 m at about 20,000 years ago. The ice cap retreated approximately 10,000 years ago. However, field data from deep boreholes in sedimentary rocks of southern Ontario show anomalous pore water pressure including underpressure and overpressure zones. In this paper, a large-scale coupled hydro-mechanical (HM) model is developed to investigate the hydro-mechanical (HM) response of the sedimentary rocks of southern Ontario to past glacial cycles. Particular emphasis has been placed on the evolution of pore water pressures and surface displacements. The HM model is verified using analytical solutions. The results of the large-scale HM modeling study shows that the past glaciation, particularly the second cycle (22,000 apb) had significant impact on the pore water pressure gradient and effective stress distribution in the sedimentary rocks of southern Ontario. Furthermore, good agreement between the large scale modeling results and anomalous pressures leads us to the conclusion that these anomalies could be glacially induced. The results of this research can provide information that will contribute to a better understanding of the impact of future glaciations on the long term performance of DRGs in sedimentary rocks.     

IODP333航次：科学目标、钻探进展与研究潜力

在“地震带实验项目”（NanTroSEIZE）的总体框架下,IODP333航次的任务是在日本四国岛岸外一条断面的3个站位获取岩芯。钻探于2010年12月12日至2011年1月10日实施,钻取了4个长岩芯,总长达1005m。IODP333航次的主要研究内容是陆坡、海沟底部和海山脊部的第四纪沉积过程,包括沉积层内的孔隙压力...     

EH4法勘查祥云米甸煤矿隐伏塌陷区效果

运用EH4电磁测深法布置剖面,结合岩矿石电性参数及地质资料分析,对剖面实测数据进行反演,较准确地识别出隐伏塌陷区、煤矿采空区及松散浮土层等地质异常区域及范围,较好地确定可能的地质灾害。     

胶东三山岛金矿中深部成矿流体对比及矿床成因

三山岛金矿位于胶东西北部,属于典型的破碎蚀变岩型金矿。流体包裹体研究表明该矿床为中温、中低盐度H₂O-CO₂-NaCl±CH₄流体;中深部成矿流体对比研究表明,在纵深超过2000m范围内,成矿流体具有较一致的成矿流体介质条件,主成矿均一温度为170~330℃,成矿压力为50~255MPa。H、O、C同位素表明,深源流体参与了成矿作用,很可能是与金矿床伴生的基性幔源岩浆脱水形成的岩浆水,在地壳浅部遭受到大气降水的混合,而S同位素研究进一步揭示了成矿物质具有多源性,矿区浅表在成矿晚期可能受到了表生硫影响而导致δ³⁴S偏高。水岩反应、成矿应力场转变及表面吸附电化学还原反应等导致金沉淀成矿。