Modeling three‐dimensional hydraulic fracture propagation using virtual multidimensional internal bonds

Propagation of fractures, especially those emanating from wellbores and closed natural fractures, often involves Mode I and Mode II, and at times Mode III, posing significant challenges to its numerical simulation. When an embedded inclined fracture is subjected to compression, the fracture edge is constrained by the surrounding materials so that its true propagation pattern cannot be simulated by 2D models. In this article, a virtual multidimensional internal bond (VMIB) model is presented to simulate three‐dimensional (3D) fracture propagation. The VMIB model bridges the processes of macro fracture and micro bond rupture. The macro 3D constitutive relation in VMIB is derived from the 1D bond in the micro scale and is implemented in a 3D finite element method. To represent the contact and friction between fracture surfaces, a 3D element partition method is employed. The model is applied to simulate fracture propagation and coalescence in typical laboratory experiments and is used to analyze the propagation of an embedded fracture. Simulation results for single and multiple fractures illustrate 3D features of the tensile and compressive fracture propagation, especially the propagation of a Mode III fracture. The results match well with the experimental observation, suggesting that the presented method can capture the main features of 3D fracture propagation and coalescence. Moreover, by developing an algorithm for applying pressure on the fracture surfaces, propagation of a natural fracture is also simulated. The result illustrates an interesting and important phenomenon of Mode III fracture propagation, namely the fracture front segmentation. Copyright © 2012 John Wiley & Sons, Ltd.     

Seasonal temperature extremes in Potsdam

The awareness of global warming is well established and results from the observations made on thousands of stations. This paper complements the large-scale results by examining a long time-series of high-quality temperature data from the Secular Meteorological Station in Potsdam, where observation records over the last 117 years, i.e., from January 1893 are available. Tendencies of change in seasonal temperature-related climate extremes are demonstrated. “Cold” extremes have become less frequent and less severe than in the past, while “warm” extremes have become more frequent and more severe. Moreover, the interval of the occurrence of frost has been decreasing, while the interval of the occurrence of hot days has been increasing. However, many changes are not statistically significant, since the variability of temperature indices at the Potsdam station has been very strong.     

Modeling the effects of riparian planting strategies on stream temperature: Increasing suitable habitat for endangered Formosan Landlocked Salmon in Shei‐Pa National Park,Taiwan

Reducing or stabilizing the stream temperature of ChiChiaWan Creek is a crucial work for Formosan Landlocked Salmon because ChiChiaWan Creek is the only one habitat for this endangered species. Planting trees in the riparian zone would be one of the alternatives. The purpose of this study was to evaluate the effects of several planting strategies on daily maximum stream temperature along the river. The results showed the effective vegetative shading angles should be more than 50° along ChiChiaWan Creek to reduce the direct solar radiation heating effectively. Upstream planting with 70° vegetative shading angle could be the most effective way among all the scenarios. However, this planting strategy could not improve the worst situations in summer because of the large solar elevation angles. The upstream planting in ChiChiaWan Creek was strongly recommended because the canopies could be easier to extend to totally cover the narrow width of river producing the most effective shades. Practicing the upstream planting with 90° vegetative shading angle can increase more than 1 km long suitable habitats for the endangered Salmon in summer. Alternatively, the west‐side planting scenario was the second effective way for temperature reduction. Our result provided a useful suggestion for the authorities in charge of saving the Formosan Landlocked Salmon, particularly under the stress of global warming. Copyright © 2011 John Wiley & Sons, Ltd.     

利用U—1000型激光拉曼探针测定流体包裹体气体成分的研究

本文利用U－1000型激光拉曼探针成功地测量出单个流体包裹体中H2S、CH4、CO2气体成分，并讨论了包裹体中这些气体的拉曼谱峰位移与包裹体内压的关系，分析了影响激光拉曼探针定量测定包裹体气相成分的取面积和拉曼定量因子因素。     

The vascular flora of the Qomolangma-Xixabangma region,Tibet

According to the classification and statistics of the specimens collected in the Xixabangma-Qomolangma region there are a total of 1624 species of vascular plants (136 families, 573 genera). Based on the statistics of the 573 genera of vascular plants, 14 distribution types are derived (Cosmopolitans, pantropical, tropical asian-american, palaeotropical, indo-malayan, north-temperate, east-asian-north-american disjunctions, temperate asian, central asian, tethys elements, endemic etc.). The origin of the flora of the area under consideration is polygenetic. There is no endemic family, but there are 14 endemic genera and 240 endemic species. The majority of the endemic species are derived from large and polytypic genera. The group of endemic species and varieties show that the flora of Xixabangma-Qomolangma is young and under violent floristic differentiation.     

N1923-DA201大孔吸附树脂反相分配色层分离、偶氮胂Ⅲ比色测定矿石中钍

用N1923-二甲苯作固定相,AD201大孔聚二乙烯苯吸附树脂作裁体,研究了钍在硫酸介质中的反相分配色层分离条件。拟定了矿石中微量钍的测定方法。     

Inspection test of pile Quality with Weak Stress Wave Method

This paper describes theoretical basis, test technique , data interpretation for pile quality inspection. The propagation and attenuation law of weak stress waves in concrete piles, relationship between concrete strength and elastic wave velocity are discussed. A criterion of inspecting pile quality is proposed. The study mentioned in this paper has practical value and theoretical significance for field inspection test of pile quality.     

红砂岩修筑浆砌石坝的岩土工程研究

红砂岩为中低强度岩层、岩相复杂多变,较易风化、软化。本文通过工程实践阐述了在红砂岩分布地区利用当地材料建造浆砌块石坝的岩土工程研究,开创了红砂岩筑坝的先例。     

上海地区深部构造特征和地震活动趋势探讨

本文介绍由重磁资料计算上海地区居里面、莫霍面、均衡重力异常及地幔流应力场的方法和成果,并在对成果初步分析的基础上,探讨了深部地质构造特征及其与地震活动趋势的关系,其中着重讨论了居里面及其与地震活动的关系。文章最后提出了对上海地区地震活动趋势的几点认识。     

焦耳效应标定高温卡尔维微量热计

根据热流式量热计的Tian氏方程,用焦耳效应标定高温卡尔维微量热计。用偏差法得到的灵敏度值与积分法测得的值一致。用回归曲线对灵敏度实验值进行拟合,利用计算机求得灵敏度—温度回归曲线,得到了室温至700℃的全部灵敏度值,从而即可使用微量热计测量此温度范围内的未知样品热效应。