上海中心城就业中心体系测度————基于手机信令数据的研究

利用手机信令数据识别上海市域内手机用户的工作地和居住地,获取就业者的通勤数据,测度上海中心城的就业中心体系.首先用就业者工作地数据生成就业密度分布图,基于中心城的就业密度识别就业中心.随后,用就业者工作地和居住地数据分别从就业密度和通勤联系两方面测度各中心的能级,分析各中心的腹地和势力范围.研究发现:① 上海中心城的就业中心呈主中心强大的弱多中心体系;② 就业密度越高的中心与其他地区的通勤联系一般也越强,但通勤联系在各中心间的差异更显著;③ 能级越高的中心腹地面积越大,但势力范围不一定越大;④ 相比于能级,职住功能混合度对职住平衡的影响更大;⑤缺少就业中心的地区势力范围呈交替状.本研究一定程度上能有助于解决既往就业中心体系研究因空间单元较大,缺少通勤数据在中心识别,通勤联系测度等方面受到的局限,希望能为构建上海中心城就业多中心体系提供帮助.     

Preliminary studies on the dynamic prediction method of rainfall-triggered landslide

Rainfall-triggered landslides have posed significant threats to human lives and property each year in China. This paper proposed a meteorologicalgeotechnical early warning system GRAPES-LFM(GRAPES: Global and Regional Assimilation and Pr Ediction System; LFM: Landslide Forecast Model),basing on the GRAPES model and the landslide predicting model TRIGRS(Transient Rainfall Infiltration and Grid-based Regional Slope-Stability Model) for predicting rainfall-triggered landslides.This integrated system is evaluated in Dehua County,Fujian Province, where typhoon Bilis triggered widespread landslides in July 2006. The GRAPES model runs in 5 km×5 km horizontal resolution, and the initial fields and lateral boundaries are provided by NCEP(National Centers for Environmental Prediction) FNL(Final) Operational Global Analysis data. Quantitative precipitation forecasting products of the GRAPES model are downscaled to 25 m×25 m horizontal resolution by bilinear interpolation to drive the TRIGRS model. Results show that the observed areas locate in the high risk areas, and the GRAPES-LFM model could capture about 74% of the historical landslides with the rainfall intense 30mm/h. Meanwhile, this paper illustrates the relationship between the factor of safety(FS) and different rainfall patterns. GRAPES-LFM model enables us to further develop a regional, early warning dynamic prediction tool of rainfall-induced landslides.     

玲珑金矿西山幔源脉岩地球化学特征

玲珑西山幔源脉岩主微量元素的变化暗示了源岩很可能经历过类似俯冲带流体的交代作用,矿化流体中含有较高含量的金属矿物,具有Eu的正异常,指示了源区是深源的。脉岩中的CO2来源可能是花岗岩岩浆热液的混入,石英来源于陆壳碎屑物质部分熔融形成的S型花岗岩,硫的来源与幔源脉岩岩浆同源,或来自地幔,或来自地壳深部。     

胶东埠上金矿煌斑岩地球化学特征及成因

大量的研究资料表明煌斑岩与金矿在空间上、时间上具明显的对应关系。埠上金矿位于胶东玲珑金矿田西南方向的金岭金矿田的中北部;有关该矿区煌斑岩的研究资料较少。该文结合岩石学、矿物学、大地构造学等特征,对区内煌斑岩的地球化学进行了研究,揭示其内在成因,认为区内煌斑岩是因该区受到古太平洋板块的俯冲、华北板块与杨子板块碰撞造山及郯庐断裂带等构造岩浆活动的影响,俯冲洋壳析出的流体交代地幔形成的具氧化性的EM1型富集型地幔岩浆于造山拉张期在大陆活动边缘浅成侵入而成的。     

Variability of levee failure mechanisms subject to heavy rainfalls,case studies in Taiwan

In this study, the failure mechanisms for Chiuliao 1st Levee and Gueishan Levee in Taiwan were re-examined comprehensively considering the uncertainty of different parameters. Results have shown that for Chiuliao 1st Levee, the slope sliding failure has a higher coefficient of variation (COV). For Gueishan Levee, retaining wall sliding and overturning failure have higher values of COV instead. It can also be found that the scouring depths affect the stability of the levee significantly, therefore, a protecting system for the backfill material may be necessary to increase the stability of the levee effectively.     

Strength criterion for cross-anisotropic sand under general stress conditions

By incorporating the fabric effect and Lode’s angle dependence into the Mohr–Coulomb failure criterion, a strength criterion for cross-anisotropic sand under general stress conditions was proposed. The obtained criterion has only three material parameters which can be specified by conventional triaxial tests. The formula to calculate the friction angle under any loading direction and intermediate principal stress ratio condition was deduced, and the influence of the degree of the cross-anisotropy was quantified. The friction angles of sand in triaxial, true triaxial, and hollow cylinder torsional shear tests were obtained, and a parametric analysis was used to detect the varying characteristics. The friction angle becomes smaller when the major principal stress changes from perpendicular to parallel to the bedding plane. The loading direction and intermediate principal stress ratio are unrelated in true triaxial tests, and their influences on the friction angle can be well captured by the proposed criterion. In hollow cylinder torsional shear tests with the same internal and external pressures, the loading direction and intermediate principal stress ratio are related. This property results in a lower friction angle in the hollow cylinder torsional shear test than that in the true triaxial test under the same intermediate principal stress ratio condition. By comparing the calculated friction angle with the experimental results under various loading conditions (e.g., triaxial, true triaxial, and hollow cylinder torsional shear test), the proposed criterion was verified to be able to characterize the shear strength of cross-anisotropic sand under general stress conditions.