不同倾角多层节理深部岩体开挖变形破坏规律模型试验研究

深部资源开发中地下洞室围岩稳定控制必须面对峰后碎裂岩体的变形和破坏问题,目前深部多裂隙岩体开挖强卸荷引起的围岩变形破坏规律尚不清楚,常导致大体积塌方、大变形等重大工程事故。采用大尺度三维模型相似试验系统,分析具有不同倾角的多层节理的岩体在高地应力下开挖变形破坏规律。试验结果表明：裂隙倾角较小时,隧道上、下侧围岩主要发生大变形,左、右侧围岩呈现分层破裂现象,随着裂隙倾角增大,破裂区从洞室左、右两侧逐渐扩展到洞室全周,顶部岩体越容易发生大体积滑塌;隧道围岩由内向外应力和位移值呈波动状分布;洞周塑性区范围随裂隙倾角增大而增大,裂隙倾角越大,洞周塑性区越容易与洞室上、下侧裂隙面连通。该研究为保障深部工程的安全修建与运营提供了试验基础。     

塔里木河干流上游洪水演进规律分析与数值模拟

塔里木河流域的水文特性在过去几十年内发生了深刻变化,源流的年径流总体增加,而干流发生量级洪水的频次与洪峰流量也有显著增长,干流防洪压力不断增长。通过从洪水传播时间、削峰率、耗水率三个方面对塔里木河干流上游（肖夹克-英巴扎）分河段展开系统分析,揭示了干流上游洪水传播的一般规律;在此基础上构建了一维水沙演进的数学模型,模型通过2010年洪水验证后,模拟了2017年干流洪水演进过程,模拟结果精度较高,显示了该数学模型的合理性和广阔的应用前景。研究成果不但从科学上揭示了中亚代表性内陆多沙河流的洪水特性,对于塔里木河干流的防洪管理与洪水资源化利用也有重要意义。     

SCALES: a large‐scale assessment model of soil erosion hazard in Basse‐Normandie (northern‐western France)

The cartography of erosion risk is mainly based on the development of models, which evaluate in a qualitative and quantitative manner the physical reproduction of the erosion processes (CORINE, EHU, INRA). These models are mainly semi‐quantitative but can be physically based and spatially distributed (the Pan‐European Soil Erosion Risk Assessment, PESERA). They are characterized by their simplicity and their applicability potential at large temporal and spatial scales. In developing our model SCALES (Spatialisation d'éChelle fine de l'ALéa Erosion des Sols/large‐scale assessment and mapping model of soil erosion hazard), we had in mind several objectives: (1) to map soil erosion at a regional scale with the guarantee of a large accuracy on the local level, (2) to envisage an applicability of the model in European oceanic areas, (3) to focus the erosion hazard estimation on the level of source areas (on‐site erosion), which are the agricultural parcels, (4) to take into account the weight of the temporality of agricultural practices (land‐use concept). Because of these objectives, the nature of variables, which characterize the erosion factors and because of its structure, SCALES differs from other models. Tested in Basse‐Normandie (Calvados 5500 km²) SCALES reveals a strong predisposition of the study area to the soil erosion which should require to be expressed in a wet year. Apart from an internal validation, we tried an intermediate one by comparing our results with those from INRA and PESERA. It appeared that these models under estimate medium erosion levels and differ in the spatial localization of areas with the highest erosion risks. SCALES underlines here the limitations in the use of pedo‐transfer functions and the interpolation of input data with a low resolution. One must not forget however that these models are mainly focused on an interregional comparative approach. Therefore the comparison of SCALES data with those of the INRA and PESERA models cannot result on a convincing validation of our model. For the moment the validation is based on the opinion of local experts, who agree with the qualitative indications delivered by our cartography. An external validation of SCALES is foreseen, which will be based on a thorough inventory of erosion signals in areas with different hazard levels. Copyright © 2010 John Wiley & Sons, Ltd.     

The principle of coupled stress release model and its application

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改进的能量守恒方法及其在CHAMP重力场恢复中的应用

An efficient method for gravity field determination from CHAMP orbits and accelerometer data is referred to as the energy balance approach. A new CHAMP gravity field recovery strategy based on the improved energy balance approach IS developed in this paper. The method simultaneously solves the spherical harmonic coefficients, daily Integration constant, scale and bias parameters. Two 60 degree and order gravitational potential models, XISM-CHAMPO1S from the classical energy balance approach, and XISM-CHAMPO2S from the improved energy balance, are determined using about one year＇s worth of CHAMP kinematic orbits from TUM and accelerometer data from GFZ. Comparisons among XISM-CHAMPO1S, XISM-CHAMPO2S, EIGEN-CGO3C, EIGEN-CHAMPO3S, EIGEN2, ENIGNIS and EGM96 are made. The results show that the XISM-CHAMPO2S model is more accurate than EGM96, EIGENIS, EIGEN2 and XISM-CHAMPO1S at the same degree and order, and has almost the same accuracy as EIGEN-CHAMPO3S.     

南海中部海域障碍层特征及其形成机制

南海中部海域(10°~19°N,108°~122°E)存在显著的季节变化的障碍层.障碍层发生概率夏季最大(52.8%),秋季次之(41.0%),春季最小(10.5%).夏季(2000年8~9月)障碍层最显著,平均厚度约为14.2m;除114°E以东、吕宋岛以西海域为障碍层的多发区外,中南半岛东南海域(12°~14°N,110°~114°E)也存在显著的障碍层;春季(1998年4~6月)和秋季(1998年12月)障碍层平均厚度分别为6.8和11.2m,障碍层多位于114°E以东、吕宋岛以西海域.此外,吕宋岛以西海域(12°~16°N,116°~120°E)及中沙和西沙群岛附近(16°~18°N,110°~116°E)海域障碍层年发生几率超过20%,相对而言,其他海域障碍层年发生几率偏小.降水机制和层结机制分别是南海中部海域春、夏季和秋季障碍层形成的主要原因.其中,降水机制及东南向的Ekman平流较好的解释了春、夏季吕宋岛以西附近海域成为障碍层多发区的原因;此外,强降水是夏季中南半岛东南海域(12°~14°N,110°~114°E)障碍层产生的关键,反气旋涡(暖涡)有助于形成更强的障碍层,上升流对障碍层的影响有待进一步研究.     

A new efficient 3D non-hydrostatic free-surface flow model for simulating water wave motions

A new three-dimensional, non-hydrostatic free surface flow model is presented. For simulating water wave motions over uneven bottoms, the model employs an explicit project method on a Cartesian the staggered gird system to solve the complete three-dimensional Navier–Stokes equations. A bi-conjugated gradient method with a pre-conditioning procedure is used to solve the resulting matrix system. The model is capable of resolving non-hydrostatic pressure by incorporating the integral method of the top-layer pressure treatment, and predicting wave propagation and interaction over irregular bottom by including a partial bottom-cell treatment. Four examples of surface wave propagation are used to demonstrate the capability of the model. Using a small of vertical layers (e.g. 2–3 layers), it is shown that the model could effectively and accurately resolve wave shoaling, non-linearity, dispersion, fission, refraction, and diffraction phenomena.     

空间分辨率对总初级生产力模拟结果差异的影响

利用模型分析气候变化对陆地生态系统功能的影响,是当前全球变化生态学的研究热点,然而模型模拟不确定性来源之一就是空间异质性的问题。空间异质性是尺度的函数,基于气象和遥感数据驱动的生态系统过程模型（BEPS模型）,分别模拟2003-2005年中国生态系统通量观测与研究网络（ChinaFLUX）长白山站、千烟洲站、海北站及当雄站在1 km和8 km空间分辨率下的总初级生产力（GPP）的时间动态变化,并结合土地覆盖类型及叶面积指数(LAI)的差异,探讨两种空间分辨率输入数据对GPP模拟结果的影响。结果表明：① 差异性主要是由于8 km范围内混合像元导致LAI的不同,4个站点月均差异值分别为0.85、1.60、0.13及0.04;② 两种空间分辨率均能较好地反映各站点GPP的季节动态变化,与GPP观测值的相关性R²为0.79~0.97 (1 km)、0.69~0.97(8 km),月均差异值为11.46~29.65 gC/m²/month (1 km)、11.87~24.81 gC/m²/month (8 km);③ 4个通量站点在两种空间分辨率下的GPP月均差异值分别为14.43,12.05,4.79,3.22 gC/m²/month,不同空间分辨率的模拟结果在森林站的差异大于草地站,且生长季的差异大于非生长季。因此,模型在模拟大尺度、长时间序列GPP时,为了提高模型模拟效率,适度降低空间分辨率是可行的,但应尽量减小低空间分辨率对于森林生态系统以及生长季GPP模拟上的误差。     

PM2.5污染对中国人口死亡率的影响——基于346个城市面板数据的实证分析

中国生态文明建设和“健康中国”战略强调切实治理影响人口健康的环境问题,建设健康人居环境。论文基于2000年和2010年中国人口普查资料以及2005年和2015年各省级行政单元1%人口抽样调查等数据资料,论文使用探索性空间分析方法刻画中国城市人口死亡率的时空变化特征,并采用空间回归方法,揭示城市PM_2.5的平均浓度对人口死亡率的影响及其空间溢出效应,以及社会经济因素对PM_2.5—人口死亡率关联的调节效应。结果表明：① 中国城市人口死亡率的空间分布特征呈现明显的异质性,高死亡率地区早期集聚分布于西南地区,2005年后在西南地区、华北地区、华东地区和华中地区呈现逐渐集聚分布态势。低死亡率地区长期集中分布于西北地区、东北地区、长三角地区、珠三角地区和京津两市。② 人口死亡率的分布存在空间关联性,高—高类型地区早期集中分布于西南地区,后期向东扩展;低—低类型地区主要分布于北疆、内蒙古西部和广东省及其周边地区。③ 城市PM_2.5浓度对人口死亡率具有显著的正向影响,并且对邻近地区的人口死亡率具有显著的空间溢出效应。④ 中国城市PM_2.5浓度对人口死亡率的影响存在学历差异和城乡差异,地区高学历人群集聚可降低PM_2.5的健康风险,城镇化发展进程缓慢则会加重PM_2.5的健康风险。研究旨在为防范空气污染暴露导致的健康风险、建设健康人居环境提供科学依据。     

Implementing quality control on a random number stream to improve a stochastic weather generator

For decades, stochastic modellers have used computerized random number generators to produce random numeric sequences fitting a specified statistical distribution. Unfortunately, none of the random number generators we tested satisfactorily produced the target distribution. The result is generated distributions whose mean even diverges from the mean used to generate them, regardless of the length of run. Non‐uniform distributions from short sequences of random numbers are a major problem in stochastic climate generation, because truly uniform distributions are required to produce the intended climate parameter distributions. In order to ensure generation of a representative climate with the stochastic weather generator CLIGEN within a 30‐year run, we tested the climate output resulting from various random number generators. The resulting distributions of climate parameters showed significant departures from the target distributions in all cases. We traced this failure back to the uniform random number generators themselves. This paper proposes a quality control approach to select only those numbers that conform to the expected distribution being retained for subsequent use. The approach is based on goodness‐of‐fit analysis applied to the random numbers generated. Normally distributed deviates are further tested with confidence interval tests on their means and standard deviations. The positive effect of the new approach on the climate characteristics generated and the subsequent deterministic process‐based hydrology and soil erosion modelling are illustrated for four climatologically diverse sites. Copyright © 2007 John Wiley & Sons, Ltd.