顾及降雨影响的动态优化时滞时序GM(1,2)模型在滑坡位移预测中的应用

滑坡体除了因自身重力产生位移外,还受到降雨的影响,但通常降雨对滑坡位移的作用具有滞后性。为了分析并预测降雨对滑坡位移的影响,本文提出一种顾及降雨影响的动态优化时滞时序GM(1,2)滑坡位移预测模型。首先,利用经验模态分解(EMD)分解位移序列并通过时间序列重构得到周期位移序列和趋势位移序列,对降雨数据和滑坡周期位移序列进行时滞分析和相关分析,确定时滞时间和影响程度,建立基于背景值优化的动态时滞GM(1,2)模型预测降雨量变化导致的滑坡周期位移变化;然后,建立门限自回归模型预测滑坡趋于自然变化的趋势位移;最后,通过时序叠加得到顾及降雨影响的滑坡预测位移,建立了顾及降雨因素的动态优化时滞时序GM(1,2)组合预测方法。本文以福宁高速公路八尺门滑坡和秭归县八字门滑坡监测数据为例,验证了动态优化时滞GM(1,2)模型的精度,并与其他模型的预测结果进行了对比分析。试验结果表明,动态优化时滞时序GM(1,2)组合预测模型能准确地预测降雨影响导致的滑坡位移变化,预测效果较好,该组合模型对滑坡灾害的预警与防治具有一定的参考价值。     

黄河三角洲滨海湿地不同盐分质量浓度下土壤微生物死亡残体的差异

利用微生物生物标识物（氨基糖）,探讨盐分对黄河三角洲滨海湿地土壤微生物残体以及微生物残体对土壤有机碳（SOC）库贡献的影响。在滨海湿地生态系统中,随着土壤盐分增加,微生物死亡残体及其对SOC的贡献显著降低,表明高盐滨海湿地不利于土壤微生物死亡残体的积累及其对SOC的贡献。增加的盐分降低了土壤真菌死亡残体与细菌死亡残体的比值。线性回归分析指出土壤含水量、SOC、总氮（N）、交换性钙离子以及真菌死亡残体/细菌死亡残体与微生物死亡残体对SOC的贡献显著正相关。在低盐滨海湿地,良好的土壤条件（如高的水分、SOC和N）通过增加微生物死亡残体的积累和稳定性,促进了SOC的存储;而在高盐滨海湿地,低的可利用碳抑制了微生物死亡残体对SOC的贡献。另外,从低盐到高盐滨海湿地,真菌死亡残体对SOC的贡献逐渐下降,而细菌死亡残体对SOC的贡献没有变化,表明真菌死亡残体的积累对SOC的存储具有较大的影响。     

基于空间溢出效应的粮食主产区粮食增产与农业生态污染关系研究

采用空间计量模型,立足于粮食主产区,并引入非主产区作为对照,通过评估主产区与非主产区粮食增产对农业生态污染的影响,探讨粮食增产与农业生态变化关系。结果表明：① 粮食产量与农业生态污染均存在显著的空间相关性,且两个变量的空间相关性在时间上存在异质性,这就意味着空间同质性假说不再适用,传统的关于粮食增产影响生态污染的研究可能存在局限性;② 粮食增产并未加剧农业生态恶化。粮食主产区的设立本是为了保障粮食安全,其结果是不仅在一定程度上扭转了“非粮化”的趋势,还削弱了对农业生态环境的污染;③ 粮食增产并未加剧农业生态恶化的原因在于,粮食生产规模比重的增加所产生的规模效应和一系列行之有效的政策措施降低了粮食主产区的化肥施用强度,而农业机械化投入对农业生态污染的影响存在一定的门槛效应,大中型农机跨区服务可能有利于减少主产区农业生产对生产环境的污染程度。上述结论意味着粮食安全与生态保护之间不存在不可调和的矛盾;未来在农业适度规模经营过程中应激发农业机械化抑制农业生态恶化的潜能;考虑到空间效应的影响,应建立邻近区域农业污染治理联动机制。     

生物炭对土壤理化性质影响的研究进展简

Biochar is an organic material with high carbon content, most aromatic structure and great stability resulting from high temperature thermal conversion (usually < 700 ℃) of organic materials under the completely or in part anoxic condition. Due to its stable chemical properties, biochar has received widely attention as a strategy to reduce greenhouse gas emissions. In addition, biochar shows great potential in soil improvement and environmental pollution remediation, and provides a comprehensive solution for the global climate change, food crisis and ecological pollution remediation. Biochar is a carbon rich material, in association with porous characteristics and high surface area which are favorable to accumulating soil moisture, to increasing the porosity, to reducing density and bulk density, and to promoting the formation of soil aggregation. All the above soil physical improvement can provide a good environment for the growth of plants. Furthermore, biochar is an ideal acidic soil amendment which can improve the pH of acidic soil. It contains nutrient element which can be directly released into soil, and its surface charge and functional groups are conducive to soil nutrient retention, such as the reduced leaching of NH⁺₄ and NO^-₃, PO^3-₄, therefore improve the efficiency of nutrient elements. However, the effect of biochar amendments highly influenced by raw materials and pyrolysis conditions is of inconsistent and sometimes even contrast results can be concluded. In this paper, we summarize the current status and knowledge gaps about the effect of biochar amendments on soil physical and chemical properties and some suggestions are also strengthened. Finally, some possible negative impacts of biochar application and research suggestions are discussed in order to better use of biochar in agriculture.     

A comparative micromechanical analysis of the effective properties of a geomaterial: Effect of mineralogical compositions

In order to provide a physical interpretation of the variation of the mechanical properties of Callovo-Oxfordian argillite with mineral composition, we implement three linear homogenization schemes. The argillite is modeled as a three phase material composed of a clay matrix and inclusions of quartz and calcite. It is shown that, unlike the dilute scheme and the self-consistent scheme, the Mori-Tanaka model describes the in situ experimental data well. The determined properties are finally used in a finite element computation. The aim is to evaluate the effect of mineral composition on the elastic response of the excavation of a vertical shaft in the context of the underground laboratory of Meuse/Haute Marne.     

A discrete approach for anisotropic plasticity and damage in semi-brittle rocks

In this paper, we propose an anisotropic plastic damage model for semi-brittle geomaterials based on a discrete thermodynamic approach. The macroscopic plastic deformation is generated by frictional sliding of weakness planes. The evolution of damage is related to growth of such weakness planes. The local frictional sliding in each family of weakness planes is described by a non-associated plastic model taking into account material softening and volumetric dilatancy. The damage evolution is coupled with plastic deformation and modelled by an isotropic damage criterion. The proposed model is applied to modelling mechanical responses of typical sandstone under different loading paths. There is good agreement between numerical predictions and experimental data. Further, the anisotropic distributions of plastic deformation and induced damage are analysed and discussed.     

枯季长江口南槽悬沙输运过程和机制研究

开展枯季河口悬沙输运机理研究对于揭示弱径流条件下的陆海相互作用、河口季节性冲淤和水沙关系等具有重要的科学意义.本文根据2018年12月18-25日长江口南槽3个站位连续13个潮周期的同步流速、流向和悬沙浓度等观测资料,运用通量机制分解法研究了各输沙项的特征、贡献和输运机理.结果 表明,从小潮至大潮流速和悬沙浓度不断增加,由南槽上部至下部流速和悬沙浓度逐渐降低.观测期间平均流速与平均悬沙浓度存在明显的正线性关系,但受底质空间差异影响,悬沙浓度对流速的响应强度存在显著的空间变化.枯季期间南槽存在着中上部向陆净输沙、下部向海净输沙的空间输运格局.平流输沙和潮泵输沙是影响和控制净输沙的关键因素,二者的强度和贡献存在明显的潮周期变化和空间变化,垂向环流输沙的强度很弱,对净输沙贡献很小.南槽涨落潮输沙不对称现象明显,流速、悬沙浓度和历时都具有一定的涨落潮不对称性,这些不对称现象共同调节和控制着潮周期净输沙强度和方向的时空变化.     

复杂勘探目标区岩性预测技术及其在海拉尔盆地乌南地区的应用

海拉尔盆地乌尔逊凹陷南部地区构造和断裂复杂,多物源,短物源,相变快,因而导致下白垩统南屯组岩性有利目标区预测难度大。根据层序地层学和坡折带理论,以地震资料为基础,建立了一套新的地震精细解释、复杂勘探目标区岩性体识别及三维可视化刻画等全三维地震解释技术体系。认为乌东斜坡发育三个坡折带,第三坡折带下倾方向和第二坡折带具备形成岩性油气藏的地质条件,应用频谱分析和三维可视化技术在乌东斜坡带南屯组识别有利扇体10个,面积145km2,部署探井5口,其中4口获工业性油流,1口获低产工业性油流,探井符合率100%。     

珠母贝人工苗养殖研究

在不同海区、不同水层养殖珠母贝人工苗，及用不同方法进行养殖小贝。结果表明：在开放性、半开放性、内湾性海区养殖11个月后．珠母贝壳高分别为64．5、51．4、69．8mrn．成活率分别为6．4％、0．8％、0．5％，其生长和成活率具有显著差异（P〈0．05）；同海区中3m、6m、9m、12m、15m水层养殖11个月后．珠母贝壳高分别为64．5、67．4、62．8、56．9、51．9mm．成活率分别为6．4％、6．8％、8．1％、11．7％、13．9％．随着水层的加深．珠母贝的生长变慢．成活率提高且差异显著（P〈0．05）；6个月龄小贝用穿耳法、片笼法、锥型笼法养殖5个月后．壳高分别长成56．1、55．7、51．7mm．成活率分别为72．6％、59．9％、51．7％，其生长和成活率具有显著差异（P〈0．05）。     

Changes of flow regimes and precipitation in Huai River Basin in the last half century

Huai River Basin, as the sixth largest river basin in China, has a high‐regulated river system and has been facing severe water problems. In this article, the changing patterns of runoff and precipitation at 10 hydrological stations from 1956 to 2000 on the highly regulated river (Shaying River) and less‐regulated river (Huai River) in the basin are evaluated at the monthly, seasonal and annual scales using the Mann–Kendall test and simple linear regression model. The results showed that: (1) No statistically significant trends of precipitation in the upper and middle Huai River Basins were detected at the annual scale, but the trend of annual runoff at Baiguishan, Zhoukou and Fuyang stations in Shaying River decreased significantly, whereas the others were not. Moreover, the decreasing trends of runoff for most months were significant in Shaying River, although the trend of monthly precipitation decreased significantly only in April in the whole research area and the number of months in the dry season having significantly decreasing trends in runoff was more than that in the wet season. (2) The rainfall–runoff relationship was significant in both highly regulated river and less‐regulated river. In regulated river, the reservoirs have larger regulation capacity than the floodgates and thus have the smaller correlation coefficient and t‐value. In Huai River, the correlation coefficients decreased from upper stream to downstream. (3) The regulation of dams and floodgates for flood control and water supply was the principal reason for the decreasing runoff in Huai River Basin, although the decreasing precipitation in April in this basin was statistically significant. The findings are useful for recognizing hydrology variation and will provide scientific foundation to integrated water resources management in Huai River Basin. Copyright © 2010 John Wiley & Sons, Ltd.