风积砂质高浓度胶凝充填材料性能与粉煤灰掺量关系分析

充填材料是决定煤炭充填开采效益、效率、效果的最主要因素。为了掌握风积砂质高浓度胶凝充填材料的性能变化规律,本文以粉煤灰的质量掺入比作为变量,试验研究和理论分析了粉煤灰对该充填材料性能的影响规律。结果表明,粉煤灰的适量添加可以提高充填材料的强度,大掺量导致强度相对降低; 泌水率随着粉煤灰掺量的增大总体上呈减小趋势,较大掺量试样泌水速率相对较低; 分层度随着粉煤灰掺量的增大线性降低; 凝结时间随着粉煤灰掺量增大呈现指数增大; 坍落度总体上随粉煤灰掺量的升高而增大,但大掺量会使其出现相对降低。分析认为,适量粉煤灰的掺入,使风积砂质高浓度胶凝充填材料的颗粒粒度、水分分布和水泥分散均匀,而使材料的强度和输送性能适度改变,但掺量过大会稀释胶结料和改变颗粒相对级配而导致性能下降。     

基于灰色关联度法的可拓理论在霍尔古吐水电站坝址区泥石流危险性评价中的应用

泥石流危险性评价是灾情预测、防灾救灾决策中的重要内容,是国内外灾害科学研究的热点之一。本文以新疆开都河霍尔古吐水电站坝址区群沟泥石流为研究对象,在对泥石流区域地质环境研究的基础上,选取泥石流规模、爆发频率等8个因素作为评价因子,采用灰色关联度确定评价因子权重,运用可拓理论,通过定性和类比的方法对群发泥石流区域进行危险性评价。将评价结果与刘希林提出的单沟泥石流评价结果比较,清水沟与雪莲沟的可拓法评价危险度等级要高于单沟泥石流评价结果,这一结果和现场调查情况相吻合。因此,基于灰色关联度法的可拓理论对霍尔古吐水电站坝址区群发泥石流危险度评价结果合理可靠,进而为坝区泥石流危险性评估、规划防治提供合理的科学依据。     

Investigation of highly efficient algorithms for solving linear equations in the discontinuous deformation analysis method

Large‐scale engineering computing using the discontinuous deformation analysis (DDA) method is time‐consuming, which hinders the application of the DDA method. The simulation result of a typical numerical example indicates that the linear equation solver is a key factor that affects the efficiency of the DDA method. In this paper, highly efficient algorithms for solving linear equations are investigated, and two modifications of the DDA programme are presented. The first modification is a linear equation solver with high efficiency. The block Jacobi (BJ) iterative method and the block conjugate gradient with Jacobi pre‐processing (Jacobi‐PCG) iterative method are introduced, and the key operations are detailed, including the matrix‐vector product and the diagonal matrix inversion. Another modification consists of a parallel linear equation solver, which is separately constructed based on the multi‐thread and CPU‐GPU heterogeneous platforms with OpenMP and CUDA, respectively. The simulation results from several numerical examples using the modified DDA programme demonstrate that the Jacobi‐PCG is a better iterative method for large‐scale engineering computing and that adoptive parallel strategies can greatly enhance computational efficiency. Copyright © 2015 John Wiley & Sons, Ltd.     

吉林延边汪清县蛤蟆塘盆地白恶纪地层划分及其演化

通过１∶５万区调填图（１９８８～１９９０）,笔者将蛤蟆塘盆地白垩纪地层划分为大拉子组、富兴屯砾岩、龙井组。其中大拉子组下部为山麓冲积扇沉积,上部为湖相沉积;富兴屯砾岩为河流—扇三角洲相沉积;龙井组为浅盆广湖相沉积,其中产有Ｎｉｇｅｒｅｓｔｈｅｒｉａｓｐ等化石,属早白垩世,与延吉盆地等有明显时代差异,具有穿时性。     

Variability of East Asian Winter Monsoon in Quaternary Climatic Extremes in North China

In order to examine high-frequency variations of East Asian winter monsoon in Quaternary climatic extremes, two typical loess–paleosol sequences in the Chinese Loess Plateau were investigated. Sandy layers in the loess deposits, the “Upper sand” and “Lower sand” (layers L9 and L15, respectively), which represent a high-resolution record of paleomonsoon changes, have been sampled at intervals of 5–6 cm from sections at Luochuan and Xifeng. The grain size and magnetic susceptibility was measured for all samples. The grain-size results (a proxy of winter monsoon strength) indicate that the winter monsoon strength fluctuated on a millennial timescale during cold climatic extremes, with climatic events of a few hundred to a few thousand years. However, the winter monsoon was relatively stable during warm periods. The magnetic susceptibility signal (a proxy of summer monsoon intensity) is practically constant over the same period. This is tentatively explained by the assumption that the summer monsoon intensity was too low to be recorded in the magnetic susceptibility signal. The intensified winter monsoon events show periodicities in a range of 1000 to 2770 yr, with a dominant cycle of approximately 1450 yr. The detection of this oscillation in older glacial stages strongly suggests that it may be a pervasive cycle of the cold climatic phases of the Quaternary. Millennial-scale variations of the winter monsoon may be caused by instability of the westerly jet, which is determined by temperature differences between the polar and the equatorial regions.     

Thermal equation of state of natural tourmaline at high pressure and temperature

Synchrotron-based in situ angle-dispersive X-ray diffraction experiments were conducted on a natural uvite-dominated tourmaline sample by using an external-heating diamond anvil cell at simultaneously high pressures and temperatures up to 18 GPa and 723 K, respectively. The angle-dispersive X-ray diffraction data reveal no indication of a structural phase transition over the P–T range of the current experiment in this study. The pressure–volume–temperature data were fitted by the high-temperature Birch–Murnaghan equation of state. Isothermal bulk modulus of K ₀ = 96.6 (9) GPa, pressure derivative of the bulk modulus of \(K_{0}^{\prime } = 12.5 \;(4)\), thermal expansion coefficient of α ₀ = 4.39 (27) × 10^?5 K^?1 and temperature derivative of the bulk modulus (?K/?T) _P  = ?0.009 (6) GPa K^?1 were obtained. The axial thermoelastic properties were also obtained with K _a0 = 139 (2) GPa, \(K_{a0}^{\prime }\) = 11.5 (7) and α _a0 = 1.00 (11) × 10^?5 K^?1 for the a-axis, and K _c0 = 59 (1) GPa, \(K_{c0}^{\prime }\) = 11.4 (5) and α _c0 = 2.41 (24) × 10^?5 K^?1 for the c-axis. Both of axial compression and thermal expansion exhibit large anisotropic behavior. Thermoelastic parameters of tourmaline in this study were also compared with that of the other two ring silicates of beryl and cordierite.     

Observation of CO2 degassing in Tianshuihai Lake Basin of the Qinghai-Tibetan Plateau

A large volume of underground gas in the permafrost region of the Qinghai-Tibetan Plateau has been identified. Although many studies were performed to investigate the soil organic carbon dynamics and Earth degassing in volcanic areas, this is the first report of a large amount of non-volcanic CO₂ contained in permafrost. The gas was mostly CO₂ (81.76 vol. %) and nitrogen (14.59 vol. %). The gas composition and the evidence from carbon stable isotope values (?23.9 ‰, PDB) suggested that the gases possibly had a deep origin. The gas emissions may be triggered by permafrost degradation, which means mitigation of the barrier effect of permafrost for the gas. In addition, plate tectonic processes may also lead to gas emissions, as the tectonic activity is strong in the area. Therefore, particular attention should be paid to the underground gases in the study of global change and permafrost degradation.     

The rapidly shrinking cryopshere in the past decade：an interpretation of cryospheric changes from IPCC WGI Sixth Assessment Report北大核心CSCD

The Working Group I report of the Sixth Assessment Report（AR6）of the Intergovernmental Panel on Climate Change（IPCC）was released in August 2021. Base on updated and expanding data, AR6 presented the improved assessment of past changes and processes of cryosphere. AR6 also predicted the future changes us⁃ ing the models in CMIP6. The components of cryosphere were rapid shrinking under climate warming in the last decade. There were decreasing trends in Arctic sea-ice area and thickness. Sea-ice loss was significant. The Greenland Ice Sheet, the Antarctic Ice Sheet and all glaciers lost more mass than in any other decade. Global warming over the last decades had led to widespread permafrost warming, active layer thickness increasing and subsea permafrost extent reducing. Snow cover extent in the Northern Hemisphere also decreased significantly. However, the variations of snow depth and snow water equivalent showed great spatial heterogeneity. The rapid shrinking of the cryosphere accelerated the global mean sea level rise. The impact of human activities on cryo⁃ sphere will become more significant in the future. The Arctic sea-ice area will decrease, and the Arctic Ocean will likely become practically sea ice-free. The Greenland Ice Sheet, the Antarctic Ice Sheet and glaciers will continue to lose mass throughout this century. Permafrost and Northern Hemisphere snow cover extent will con⁃ tinue to decrease as global climate continues to warm. In addition, there are still uncertainties in the prediction of cryosphere due to the absence of observations, the poor sensitivity of models to the components and processes of cryosphere, and the inexplicit represent of the mechanism of light-absorbing impurities. More attentions should be paid on these issues in the future. © 2022 Science Press (China). All rights reserved.     

2003-2010年青藏高原积雪及雪水当量的时空变化

利用MODIS逐日无云积雪产品与AMSR-E雪水当量产品进行融合, 获取了青藏高原500 m分辨率的高精度雪水当量产品, 通过研究青藏高原积雪时空动态变化特征, 分析了积雪覆盖日数、雪水当量以及总雪量的季节及年际变化. 结果表明: 青藏高原地区降雪主要集中在高海拔山区, 而高原腹地降雪较少, 降雪在空间上分布极为不均; 2003-2010年期间, 平均积雪日数呈显著减少趋势, 稳定积雪区面积在逐渐扩大, 常年积雪区面积在不断缩小. 与积雪日数时空变化相比, 雪水当量增加的区域与积雪日数增加的区域基本一致, 但喜马拉雅山脉在积雪日数减少的情况下雪水当量却在逐年增加, 表明该地区温度升高虽然导致部分常年积雪向季节性积雪过渡, 但降雪量却在增加. 总的积雪面积年际变化呈波动下降的趋势, 但趋势不显著, 且减少的比例很少. 最大积雪面积呈现波动上升后下降的趋势, 平均累积积雪总量呈明显的波动下降趋势, 年递减率为1.0×10³ m³·a^-1.     

北京西郊玉泉山地区岩溶水强径流路径地球物理分析

为研究北京西郊玉泉山地区岩溶水径流路径,需查明区内地层结构和断裂构造发育情况,故在玉泉山周边地区开展了综合地球物理勘查工作。完成1∶25000面积性重力测量3670点,在重力数据解释推断成果基础上,有针对性地布设可控源音频大地电磁测深(CSAMT)剖面测量5.1 km及微动测深点4个。综合研究了基岩起伏形态和构造展布特征,新解释推断了10条可能存在的断裂构造。结合区域水文地质资料,对主要断裂的水文地质意义进行了分析,形成了玉泉山地区岩溶水强径流路径新的认识,部分成果与最新的同位素水化学研究成果一致。本研究为玉泉山泉恢复确定合理的回灌方案提供了地球物理依据。