多层采空区条件下的高速公路路堑边坡稳定性数值分析

高速公路建设过程中常穿越各种矿山采空区,采空区对路堑边坡的稳定性产生较大的影响。基于有限差分分析的快速拉格朗算法FLAC^3D程序,由于具有强大的数值模拟分析功能,可以模拟多种结构形式的地质体,因而广泛应用于各种岩土工程问题。本文结合国家某重点交通项目,采用快速拉格朗算法FLAC^3D程序对多层采空区条件下的某路堑边坡稳定性进行了评价,主要包括开挖、注浆和锚固等工况下路堑边坡的应力和位移分析。分析结果表明,采空区经过处理后的路堑边坡是稳定的,FLAC^3D应用于多层采空区条件下的路堑边坡稳定性评价是可行的。     

Geochemical characteristics of sediment as indicators of post-glacial environmental changes off the Shandong Peninsula in the Yellow Sea

Core NYS-101, which was recovered at a water depth of 49 m northeast of the Shandong Peninsula in the North Yellow Sea, penetrates the Holocene subaqueous clinoform that wraps around the Shandong Peninsula. The uppermost 18 m of this well-dated core was deposited after about 13 cal kyr BP during the post-glacial transgression. We focused on trace and rare earth element (REE) chemistries of the core sediments in the uppermost 18 m to investigate the sediment provenance and factors controlling the sediment composition. On the basis of down-core distributions of REE fractionation parameters and of ratios among REEs and other immobile elements, we divided the uppermost 18 m into three distinct compositional intervals: Interval 1 (above 6.08 m, from the time tens of years earlier than 6500 cal yr BP up to the present), Interval 2 (13.90–6.08 m, from about 8200 cal yr BP to the boundary between Intervals 1 and 2), and Interval 3 (below 13.90 m, from about 13,000 to 10,400 cal yr BP). The chondrite- and upper continental crust (UCC)-normalized REE fractionation patterns of Intervals 3 and 2 are similar to those of Yellow River sediments, but the patterns in Interval 1 are obviously different.     

Characteristics of Far-field Precursory Anomalies Before the M_S8.1 Earthquake in the West of Kunlun Mountains Pass

In this study, a number of typical precursory anomalies recorded by stations in Qinghai, Gansu, Sichuan, Xinjiang, Ningxia, Hebei and Shaanxi provinces and autonomous regions before the M_S8.1 earthquake in the west of Kunlun Mountains Pass are collected and checked. According to the standards of earthquake cases in China, the criteria of the precursory anomalies are determined, and 53 distinguished. The characteristics of these anomalies before the M_S8.1 earthquake are analyzed, with results showing a very large earthquake affected area. The precursory anomalies recorded by instruments were 2900 km away from the epicenter, and according to the study in this paper, reached 2100 km away. The results also show that the anomalies present characteristics of long duration, multi-measurement items and large-amplitude variation. The authors believe that in large earthquake monitoring, attention should be paid to the variation of data over a large area, ranging up to thousands kilometers, with much denser earthquake observation networks.     

小兴安岭森林生态系统中小型土壤动物生态地理分布特征

对小兴安岭森林生态系统10个生境中小型土壤动物的数量和类群组成、多样性、生态地理分布及群落排序进行研究.从水平分布看,中小型土壤动物个体数最多的是人工云冷杉林,类群数最多的是赤杨林,个体数和类群数最少的均为林间草甸.中小型土壤动物在土壤中的垂直分布具有明显的表聚性,但各生境的变化情况略有不同.10个生境多样性指数和丰富度指数在人工林和相应的天然林内的变化趋势相反.而均匀度指数和优势度指数差异不大.排序结果显示云冷杉红松林、云冷杉林、赤杨林和林间草甸与其它生境差异较大.     

硫酸根分析技术及应用现状

就近年来硫酸根检测分析技术及应用现状作一综述,并着重对重量法、滴定法、原子吸收法、光度法、荧光法、离子色谱法、离子选择电极法、ICP-AES法测定硫酸根进行了评述,为在医药、食品、化工生产和环境监测方面的应用提供了依据。     

A latent class MDS model with spatial constraints for non-stationary spatial covariance estimation

Multidimensional scaling (MDS) has played an important role in non-stationary spatial covariance structure estimation and in analyzing the spatiotemporal processes underlying environmental studies. A combined cluster-MDS model, including geographical spatial constraints, has been previously proposed by the authors to address the estimation problem in oversampled domains in a least squares framework. In this paper is formulated a general latent class model with spatial constraints that, in a maximum likelihood framework, allows to partition the sample stations into classes and simultaneously to represent the cluster centers in a low-dimensional space, while the stations and clusters retain their spatial relationships. A model selection strategy is proposed to determine the number of latent classes and the dimensionality of the problem. Real and artificial data sets are analyzed to test the performance of the model.     

Estimating the 4DVAR analysis error of GODAE products

We explore the ocean circulation estimates obtained by assimilating observational products made available by the Global Ocean Data Assimilation Experiment (GODAE) and other sources in an incremental, four-dimensional variational data assimilation system for the Intra-Americas Sea. Estimates of the analysis error (formally, the inverse Hessian matrix) are computed during the assimilation procedure. Comparing the impact of differing sea surface height and sea surface temperature products on both the final analysis error and difference between the model state estimates, we find that assimilating GODAE and non-GODAE products yields differences between the model and observations that are comparable to the differences between the observation products themselves. While the resulting analysis error estimates depend on the configuration of the assimilation system, the basic spatial structures of the standard deviations of the ocean circulation estimates are fairly robust and reveal that the assimilation procedure is capable of reducing the circulation uncertainty when only surface data are assimilated.     

EXPERIMENTS WITH SHORT-TERM CLIMATE PREDICTION MODELS ON SSTA OVER THE NINO OCEANIC REGION

Predictions of averaged SST monthly anomalous series for Nino 1-4 regions in the context of auto-adaptive filter are made using a model combining the singular spectrum analysis (SSA) and auto-regression (AR). The results have shown that the scheme is efticient in forward forecaning of the strong ENSO event in 1997-1998, it is of high reliability in retrospective forecasting of three corresponding historical strong ENSO events. It is seen that the scheme has stable skill and large accuracy for experiments of both independent samples and real cases.With modifications, the SSA-AR scheme is expected to become an efficient model in routine predictions of ENSO.     

甘肃省森林、草原火灾的成因分析

简要介绍了利用NOAA极轨气象卫星资料监测森林 ,草原火灾的原理 ,结合实际工作经验 ,阐明了引起甘肃省森林、草原火灾的成因、林牧区的地理分布及特点     

喀斯特流域枯水径流频率分析——以贵州省河流为例

以贵州省各水文站控制断面为例,选择了18 个流域进行枯水频率分析。在综述国内外枯水频率研究的基础上,选择了对数正态分布、P-Ⅲ型分布、对数P-Ⅲ型分布及耿贝尔曲线四种理论分布的线型,来分析在喀斯特流域进行枯水径流频率计算时所适用的理论频率曲线,以及不同的地貌类型对所选择的曲线线型是否产生影响。研究表明,地貌类型对枯水频率曲线的线型影响不大,采用对数正态分布计算,其所造成的误差最小,其它三种方法误差则较大。