中国土地利用变化遥感研究的回顾与展望——基于陈述彭学术思想的引领

20世纪80年代以来中国社会经济快速发展带来的工业化、城市化正深刻影响着中国土地利用空间格局并影响到区域和国家生态与环境状况。在陈述彭先生指导下,1992年以来中国科学院建立起了完整的土地利用/覆盖变化遥感监测与数据分析技术路线,以及独特的分类体系和动态区划体系,奠定了中国LUCC信息平台的基础。本文在系统回顾陈述彭学术思想指导中国LUCC研究的基础上,面向国家需求与国际科技前沿梳理了我国LUCC研究的核心科学问题,并总结了中国科学院团队在最近20年LUCC研究取得的成果,包括土地利用/覆盖动态时空表征与分析模型、土地利用/覆盖变化过程及驱动机制、基于大数据和云计算的土地利用/覆盖变化探测方法、城市土地利用变化的区域气候/生态效应、气候变化与土地利用变化对农田生态系统的影响、林业活动的区域气候/生态效应,在此基础上对未来LUCC研究的前景进行了展望。     

Sensitivity of the Simulated Tropical Intraseasonal Oscillation to Cumulus Parameterizations

The sensitivity of the simulated tropical intraseasonal oscillation or MJO （Madden and Julian oscillation） to different cumulus parameterizations is studied by using an atmospheric general circulation model （GCM）--SAMIL （Spectral Atmospheric Model of IAP LASG）. Results show that performance of the model in simulating the MJO alters widely when using two different cumulus parameterization schemes-the moist convective adjustment scheme （MCA） and the Zhang-McFarlane （ZM） scheme. MJO simulated by the MCA scheme was found to be more realistic than that simulated by the ZM scheme. MJO produced by the ZM scheme is too weak and shows little propagation characteristics. Weak moisture convergence at low levels simulated by the ZM scheme is not enough to maintain the structure and the eastward propagation of the oscillation. These two cumulus schemes produced different vertical structures of the heating profile. The heating profile produced by the ZM scheme is nearly uniform with height and the heating is too weak compared to that produced by the MCA, which maybe contributes greatly to the failure of simulating a reasonable MJO. Comparing the simulated MJO by these two schemes indicate that the MJO simulated by the GCM is highly sensitive to cumulus parameterizations implanted in. The diabatic heating profile plays an important role in the performance of the GCM. Three sensitivity experiments with different heating profiles are designed in which modified heating profiles peak respectively in the upper troposphere （UH）, middle troposphere （MH）, and lower troposphere （LH）. Both the LH run and the MH run produce eastward propagating signals on the intraseasonal timescale, while it is interesting that the intraseasonal timescale signals produced by the UH run propagate westward. It indicates that a realistic intraseasonal oscillation is more prone to be excited when the maximum heating concentrates in the middle-low levels, especially in the middle levels, while westward propagating disturbances     

Effects of the undecomposed layer and semi-decomposed layer of Quercus variabilis litter on the soil erosion process and the eroded sediment particle size distribution

Simulated rainfall experiments were performed on bare, undecomposed litter layer and semi-decomposed litter layer slopes with litter biomasses of 0, 50, 100 and 150 g m⁻², respectively, to evaluate the effect of the undecomposed layer and semi-decomposed layer of Quercus variabilis litter on the soil erosion process and the particle size distribution of eroded sediment. The undecomposed layer and semi-decomposed layer of litter reduced the runoff rate by 10.91–27.04% and 12.91–36.05%, respectively, and the erosion rate by 13.35–40.98% and 17.16–59.46%, respectively. The percentage of smaller particles (clay and fine silt particles) decreased and the percentage of larger particles (coarse silt and sand particles) increased with an increased rainfall duration on all treated slopes, while the extent of the eroded sediment particle content varied among the treated slopes with the rainfall duration, with bare slopes exhibiting the largest variability, followed by undecomposed litter layer slopes and finally semi-decomposed litter layer slopes. The clay and sand particles were transported as aggregates, and fine silt and coarse silt particles were transported as primary particles. Compared with the original soil, sediment eroded from all treated slopes was mainly enriched in smaller particles. Furthermore, the loss of the smaller particles from the undecomposed litter layer slopes was lower than that from the semi-decomposed litter layer slopes, indicating that the undecomposed litter layer alleviated soil coarsening to some extent. The findings from this study improve our understanding of how litter regulates slope erosion and provide a reference for effectively controlling soil erosion.     

Downstream fining in contrasting reaches of the sand‐bedded Yellow River

Compared to downstream fining of a gravel‐bedded river, little field evidence exists to support the process of downstream fining in large, fine sand‐bedded rivers. In fact, the typically unimodal bed sediments of these rivers are thought to produce equal mobility of coarse and fine grains that may discourage downstream fining. To investigate this topic, we drilled 200 sediment cores in the channel beds of two fine‐grained sand‐bedded reaches of the Yellow River (a desert reach and a lower reach) and identified a fine surface layer (FSL) developed over a coarse subsurface layer (CSL) in the 3‐m‐thick bed deposits. In both reaches downstream, the thickness of the FSL increased, while that of the CSL decreased. Comparison of the depth‐averaged median grain sizes of the CSL and the FSL separately in both reaches shows a distinct downstream fining dependence to the median grain size, which indicates that at a large scale of 600‐800 km, the CSL shows a significant downstream fining, but the FSL shows no significant trends in downstream variations in grain size. This result shows that fine sediment supply (<0·08 mm median grain size) from upstream, combined with lateral fine sediment inputs from tributaries and bank erosion, can cause a rapid fining of the downstream channel bed surface and can develop the FSL layer. However, in the desert reach, lateral coarse sediment supply (>0·08 mm median grain size) from wind‐borne sediments and cross‐desert tributaries can interrupt the FSL and coarsen the channel bed surface locally. Copyright © 2011 John Wiley & Sons, Ltd.     

Study on Solidification Treatment of Electrolytic Manganese Slag and Numerical Simulation of Slope Stability

Geotechnical and Geological Engineering - Manganese slag contains a large number of easily migrated heavy metals and ammonia nitrogen and other pollutants, which have a negative impact on the...     

准噶尔盆地玛页1井长筒取心技术

玛页1井是新疆油田股份公司在准噶尔盆地西部隆起乌夏断裂带部署的一口风险探井,目的是探索风城组页岩油和常规高孔火山岩油藏的勘探潜力,全井设计取心275 m,实际取心445 m,该井具有取心井段长、致密泥岩地层取心效率低、裂隙发育段易堵心等特点。针对该区域地层特点及玛页1井长井段取心面临的技术难点,通过应用KT216型钻具长筒取心技术,配套井底动力高转速驱动金刚石钻进工艺,与邻井相比,玛页1井长井段取心钻进综合效率提高1.79倍,连续取心长度445 m,单回次取心长度41.97 m,创该区域历史最高纪录,可为后续该区域长井段连续取心实施提供参考和借鉴。     

基于边界位移法的地下结构推覆试验可行性研究

地震过程中地下结构变形主要受周边土体变形控制。基于该思想,现已提出一种在土?结构有限元模型侧边施加土体变形的地下结构抗震简化分析方法——边界位移法,但缺乏相关试验研究。为探索土体侧边施加推覆位移的试验方法可行性,以自行研制的岩土综合试验模型箱为试验平台,以1:10缩尺的大开车站区间隧道为研究对象,开展了大型土?地下结构系统推覆试验。通过应变、位移和应力的分析,揭示了试验过程中地下结构及周边土体的反应特性。结果表明：由于土体材料的强非线性特征,土体侧边施加的倒三角形变形在传递过程中会产生衰减,地下结构受到剪切变形和挤压变形的耦合作用;中柱与底板交接处是整体结构中的抗震薄弱位置;水平基床系数与土层位移水平及结构侧壁的破坏阶段相关;结构整体刚度大于等代土体,两者的侧向变形比值小于1。随着推覆水平增加比值逐渐增大,通过变形特征能够量化土?结构相互作用,有效填补了土?结构相互作用系数试验研究的空白。试验方法与结论,对地下结构抗震分析及推覆试验可行性研究具有重要指导意义。     

可变形圆化多边形离散单元法

将基于圆化多边形离散单元法与有限元方法结合,提出一种可变形圆化多边形离散单元法。此法对块体离散元进行圆化处理,可较好地表征不规则块体外形,又保留了颗粒离散元计算高效的优势。在求解接触力时,消除了角点处法向奇异等问题,同时增强计算的稳定性和简化接触判断。同时对切向接触力计算模型进行修正,使得接触力计算效率得到提高。此法突破了圆化多边形刚体假设的限制,可以精确计算任意形状不规则离散单元之间的相互作用,对单元的运动和变形进行模拟。通过超静定梁冲击试验、不规则块体单轴压缩试验和料斗流动“卡阻”试验3个数值模拟算例,论证此法可以有效地捕捉单元的碰撞、分离和变形等空间运动和自身特性以及其细观力学表征。     

再论鄂尔多斯盆地延长组长73砂层组与烃源岩相关的高伽马砂岩

针对自然伽马等常规测井系列长期仅能将鄂尔多斯盆地延长组长7₃砂层组大规模发育的与烃源岩相关的高伽马砂岩解释为“油页岩等优质烃源岩”的问题,根据岩心观察及测录井资料、电子探针薄片和大量页岩油实际生产资料的分析,对长7₃砂层组内与烃源岩相关的高伽马砂岩的定义、成因以及其发育特征与长7油层组页岩油试油效果的关系进行了探索性的研究。研究表明,鄂尔多斯盆地长7₃砂层组内与烃源岩相关的高伽马砂岩可划分为狭义和广义两种类型,高放射性的成因可能与深部热水作用有关,首次发现其发育特征与长7油层组页岩油试油效果关系密切。该项研究对鄂尔多斯盆地延长组长7油层组页岩油的大规模高效勘探与开发具有重要的理论和现实意义。     

北伊里安盆地北缘海底滑坡特征及成因研究

北伊里安盆地位于澳大利亚板块与太平洋板块的汇聚挤压边缘,自晚白垩世开始,澳大利亚板块不断向北移动,与太平洋板块发生多次挤压碰撞,形成了构造活动复杂区域,由此为盆地北缘海底形成广泛滑坡提供基础。通过分析盆地北部高精度的二维地震资料,对海底滑坡特征进行了详细刻画,识别出海底滑坡的3个构造单元：头部、体部和趾部,不同部位都具有其典型的地震特征。该区域海底滑坡广泛发育,分为陆坡/陆架滑坡、水道壁滑坡、峡谷滑坡和块体流沉积4种类型。结合该盆地的区域地质背景,认为板块之间的俯冲碰撞等构造运动对海底滑坡起了主要控制作用,在海底地形坡度作为内因和沉积物供给速率、海平面变化、地震活动等外界因素的共同作用下诱发海底滑坡。