节理岩体的有限元分析

本文由节理和岩块体变形迭加的方法推导出节理岩体的应力—应变关系式,并分析了各种节理和岩块体破坏的组合形式及其变形状态,因而能较准确地反映节理岩体的破坏机理。     

四扣洼陷西部沙四上亚段湖相碳酸盐岩沉积特征及沉积模式

综合运用微观薄片、岩芯、录井、测井等资料,总结了四扣洼陷西部地区沙四上亚段湖相碳酸盐岩的沉积特征,并根据古地貌特点建立了与之相应的湖相碳酸盐岩沉积模式。研究认为在洼陷缓坡带主要发育灰泥坪、岸滩、滩间和浅滩-藻礁沉积微相,而在洼陷陡坡带则主要发育灰泥坪、岸滩-藻礁沉积微相。     

Reactive rock phosphate fertilizers and soil testing for phosphorus: The effect of particle size of the rock phosphate

North Carolina rock phosphate (NCRP) (highly carbonate—substituted apatite) was ground to produce three samples with different particle size distributions. The effectiveness of these fertilizers was compared with the effectiveness of superphosphate in a field experiment and three glasshouse experiments using lateritic soils from south-western Australia. Non-reactive Queensland rock phosphate (low carbonate-substituted apatite from the Duchess deposit) was also used in the pot experiments. Bicarbonate-soluble phosphorus extracted from the soil is widely used in Western Australia to predict plant yields from previously-applied fertilizer dressings. For both field and pot experiments bicarbonate-extractable phosphorus (soil test value) was measured and related to subsequent plant yields.As calculated from the initial slope of the relationship between yield and the level of P applied, finely powdered NCRP was about 5–32% as effective as freshly-applied superphosphate in the year of application and also for two years after application in the field experiment, and for two successive crops in the three pot experiments. For both field and pot experiments, finely powdered NCRP, was at best, 1.5–2.0 times as effective as granular NCRP. Relative to freshly-applied superphosphate, the effectiveness of rock phosphates usually decreased with increasing level of application.For each of the crops in the field experiment, the relationships between yield and phosphorus content of plants (i.e. internal efficiency curves) were similar for all fertilizers. Thus the low effectiveness of the rock phosphates relative to superphosphate was solely due to much less phosphorus being taken up by plants. By contrast, in the pot experiments internal efficiency curves differed for different fertilizers. This is attributed to differences in the rate of phosphorus uptake by plant roots during the early stages of plant growth.For both field and pot experiments, soil test calibrations (the relationship between yield and soil test value) differed for rock phosphates and superphosphate. For superphosphate, soil test calibrations also differed for the three different years after the initial application of this fertilizer in the field experiment. For the second crop in the pot experiment, soil test calibrations differed for superphosphate applied at different times (before the first and the second crop). These results point out the difficulty of applying soil testing procedures to soils that have experienced different histories of fertilizer application.     

安达凹陷沙河子组烃源岩层序及地化特征浅谈

安达凹陷沙河子组地层主要发育低水位体系域;水进体系域只在局部发育,范围很小;高水位体系域在全区分布广泛。沙河子组烃源岩以暗色泥岩最为发育,其有机碳平均值为3．88％,热解S1＋S2平均值为1．360mg／g,原始生烃潜力较大;有机质类型以豫型为主;烃源岩Ro范围值为1．71％～2．43％,平均值为2．00％,在凹陷埋藏较浅地区处于高成熟阶段,其它地区Ro均高于2．0％,达到过成熟阶段。安达凹陷从1998年至今累计提交各级别储量,揭示了本区烃源岩较强的生气能力。     

火山岩油气藏水力压裂难点及其措施

火山岩可以成为良好的油气储层。由于火山岩的组成、结构及其各种勘探条件的复杂性,火山岩油气藏又是目前油气勘探的难点。常规开采方式很难取得经济产能,必须进行压裂改造。本文针对火山岩储层裂缝破裂和延伸机理认识不清、没有火山岩测试压裂解释方法以及“五高”的压裂难点,介绍了压裂破裂与延伸模型的建立、测试压裂现场快速解释技术、高温压裂液体系、水力压裂裂缝控制与延伸技术等压裂改进技术。     

基于密实核理论的单滚刀多阶段受力预测模型

基于密实核理论,针对特定岩石条件,考虑滚刀在破岩过程中复杂的受力情况,将滚刀楔形刃破岩过程分为四个阶段:弹性变形阶段、挤压破碎阶段、密实核破碎阶段与卸载阶段,且认为在密实核破碎阶段,密实核处于静水压状态,静水压力增大,会使受力物体的体积缩小,但不会改变其形状。并提出了单滚刀多阶段受力预测模型。进而开展了单滚刀线性切割岩石试验研究,并与理论模型进行了对比。结果表明:预测模型与实验数据垂直力、侧向力和滚动力的误差分别在(8~18)k N,(2~5)k N和(0~3)k N;在此基础上对预测模型进行了系数修正,使其能够更加真实地模拟滚刀破岩的受力情况,为滚刀以及刀盘的设计提供技术支撑。     

Experimental investigation of creep behavior of clastic rock in Xiangjiaba Hydropower Project

There are many fracture zones crossing the dam foundation of the Xiangjiaba Hydropower Project in southwestern China. Clastic rock is the main media of the fracture zone and has poor physical and mechanical properties. In order to investigate the creep behavior of clastic rock,triaxial creep tests were conducted using a rock servo-controlling rheological testing machine. The results show that the creep behavior of clastic rock is significant at a high level of deviatoric stress, and less time-dependent deformation occurs at high confining pressure. Based on the creep test results, the relationship between axial strain and time under different confining pressures was investigated, and the relationship between axial strain rate and deviatoric stress was also discussed. The strain rate increases rapidly, and the rock sample fails eventually under high deviatoric stress. Moreover, the creep failure mechanism under different confining pressures was analyzed. The main failure mechanism of clastic rock is plastic shear, accompanied by a significant compression and ductile dilatancy. On the other hand, with the determined parameters, the Burgers creep model was used to fit the creep curves. The results indicate that the Burgers model can exactly describe the creep behavior of clastic rock in the Xiangjiaba Hydropower Project.     

Life on a seamount: Lake charr at Stannard Rock,Lake Superior, 2011–2015

Lake Superior has four extant lake charr ecotypes including the ubiquitous lean (shallow-water form), the deep-water siscowet, and the less common, mid-depth redfin and humper forms. Stannard Rock is a distant seamount in Michigan waters that is a coveted recreational lean lake charr fishing destination. Lake charr at Stannard Rock were surveyed during 2011–2015 using gill nets set in waters <80 and ≥80 m to assess population status. All four ecotypes were found at Stannard Rock with leans being most abundant at depths <80 m and humpers and siscowets most abundant in waters ≥80 m. Few redfins were found. Total annual mortality was estimated to be 24% for leans, 18% for humpers, and 15% for siscowets. Population age and size structure of lake charr were broad with many fish older than 20 years and >700 mm. Asymptotic length was 891 mm for leans, 459 mm for humpers, and 938 mm for siscowets. Female length at 50% maturity was 547 mm for leans, 382 mm for humpers, and 453 mm for siscowets. Recreational fishery total harvest of leans peaked at 5,000 fish per year during 2011–2015. Overall, lake charr populations at Stannard Rock were healthy. Caution must be exercised because harvest levels were modest at Stannard Rock, which has a small area relative to nearshore lake charr habitat. These findings support the concept put forth by progressive recreational fishers that have advocated assigning Stannard Rock as a heritage fishery area with restrictive regulations to maintain its sustainability.     

岩石力学数值方法的作用与地位浅析

论述了岩石力学传统的研究方法的局限性，指出了岩石力学数值研究方法的优势与作用，同时探讨了岩石力学数值方法、数值分析软件当前存在的问题及不足，分析了21世纪岩石力学数值方法所能承担的及应该承担的任务。     

Electrochemical characteristics of Li2−xVTiO4 rock salt phase in Li-ion batteries

Li_2−xVTiO₄/C sample with a disordered rock salt structure was successfully prepared by annealing at a temperature of 850 °C. The electrochemical oxidation in the first cycle occurs at voltages above 4 V vs. metallic lithium, while the shapes of the electrochemical curves in consequent reduction-oxidation processes show a monotonous change of the potential between the selected cut-off voltages. A linear combination fit of individual XANES spectra was used for the determination of the oxidation states of as prepared sample and intermediate states during oxidation and reduction. In the as-prepared sample, vanadium was found to be in the average oxidation state of V^3.5+ and was additionally oxidized to V^3.8+ by the electrochemical charging. During the discharge process, the vanadium oxidation state was reduced to V^3.0+. In situ X-ray diffraction patterns and EXAFS analysis suggest good structural stability during oxidation and reduction, which is also reflected in the cycling stability if batteries were cycled in the voltage window between 2.0 V and 4.4 V. Extension of the lower cut-off voltage to 1.0 V doubles the capacity retention with the improved capacity stability if compared with several high capacity vanadium based materials.