Characterizing the deformation behavior of Tertiary sandstones

Tertiary sandstones possess deformational behavior different from hard rocks, especially the relatively larger amount of volumetric dilation during shearing. Such excess dilation contributes to the increase of crown settlement during tunnel excavation and accounts for several cases of tunnel squeezing within Tertiary sandstones. Therefore, the deformation behavior of Tertiary sandstones sampled from more than 13 formations was studied. To distinguish the volumetric deformation induced by hydrostatic stress or by shear stress as well as to decompose the elastic and the plastic components of strains, special experimental techniques, including pure shear tests and cycles of loading–unloading were applied.The experimental results reveal that the deformation of Tertiary sandstone exhibits the following characteristics: (1) significant amount of shear dilation, especially elastic shear dilation; (2) non-linear elastic and plastic deformation; (3) plastic deformation occurs prior to the failure state. Furthermore, features of plastic deformation were inferred from experimental results and, as a result, the geometry of plastic potential surface and the hardening rule were accordingly determined. A constitutive model, involving nonlinear elastic/plastic deformation and volumetric deformation induced by shear stress, is proposed. This proposed model simulates the deformational behavior for the shear-dilation-typed rocks reasonably well. Furthermore, tests on the versatility of the proposed model, including varying hydrostatic stress and stress paths, indicate that the proposed model is capable of predicting deformational behavior for various conditions.     

陆丰城区旧城改造探析

城市建设反映地方的社会、经济发展水平，因为各种各样的原因，陆丰市（指城区，下同）新区开发缓慢，旧城老化严重，城市建设水平明显落后于周边其他县市。为了改善人居环境，提高城市建设水平，加快城市建设步伐，政府制定了一系列方针政策，旧城改造作为人民群众迫切需要和城市建设的重要任务已经提到政府的工作日程上，因此探析陆丰市旧城状况和改造思路具有重要的现实意义。     

裂解碳五选择性加氢研究

将裂解C5馏分资源经选择性加氢、醚化,合成了高辛烷值汽油调和组分。为满足醚化催化剂的要求,进行了蒸汽裂解C5双烯烃选择性加氢工艺研究,对裂解C5双烯烃选择性加氢催化剂进行了评价,考察了反应压力、空速、反应温度、氢烯摩尔比对双烯烃选择性加氢的影响,得出适宜工艺条件为:反应压力0.5～1.5 MPa,温度45～80℃,空速10～2．0 h-1 ,氢烯摩尔比大于1.1。     

开槽管状药内弹道模型及计算

该文根据开槽管状药的装药结构特点,建立两相流内弹道理论模型.在定义了开槽管状药的肉厚与槽宽的基础上,推导出形状函数,采用差分方法求解.计算结果表明,开槽管状药透气性好,点传火容易,压力波振幅小,计算结果符合膛内射击过程的变化规律.     

子寅油田仑16块周期注水试验研究

百色盆地子寅油田仑16块砂岩油藏已进入特高含水开发后期,水驱剩余可采储量少,注水开发效果差,为提高区块采收率和开发效果,开展了周期注水先导试验。试验结果表明:周期注水改善了水驱开发效果,产油平稳,含水下降2．41%,采收率提高5．57%。在降压半周期动态表现为:含水下降、含水平稳和含水波动略有上升三个阶段;各井组单位压降产液也出现逐渐上升、相对平稳和略下降三个阶段。注水周期以4～6个月比较合适。该试验的成功对砂岩油藏周期注水改善开发效果具有重要的指导意义。     

一种新型发射技术-冲压加速原理

介绍一种新型发射技术──冲压加速原理，它在仅仅利用化学能的条件下，可将弹丸加速到超过２ｋｍ／ｓ的非常规初速，加速效率很高，弹迫效率可高达３０％，是一种很有发展前途的超高速发射技术。     

MCS接枝共聚物的结构和形态

将甲基丙烯酸甲酯（ＭＭＡ）、苯乙烯（Ｓ）在氯化聚乙烯（ＣＰＥ）存在下进行悬浮接枝共聚，获得ＭＣＳ树脂。本文着重考察了ＭＣＳ树脂的化学结构及胶粒形态。结果表明，确实发生了接枝共聚。ＣＰＥ用量、ＲＳＨ含量、引发剂浓度、反应温度、溶胀时间及聚合转化率对ＭＣＳ树脂的接枝率、接枝效率均有影响。ＭＣＳ树脂是接枝共聚物、ＭＭＡ／Ｓ共聚物与ＭＭＡ均聚物的混合物，橡胶相ＣＰＥ在ＭＣＳ树脂中的分散情况为“海岛结构”，     

电力滤波装置调谐,调试与测试方法的优化

本文通过对滤波器调谐、调试和测试实践中发现的问题，作了剖析．主要针对方法上的原因．作了具体的阐述，并通过对方法的优化，节省现场工作时间２０％，滤波装置的调试精确度也提高达１５％左右，取得的效果比效明显。     

Seasonal patterns of deaths in Matlab, Bangladesh

BACKGROUND: Deaths exhibit a seasonal pattern in most parts of the world. Analyses of deaths for the years 1972-1974 from the vital registration system of Matlab, Bangladesh, published in this journal 17 years ago, showed sinusoidal seasonal patterns. As death rates have declined in other nations, the seasonal pattern is attenuated. Death rates have declined substantially in Bangladesh in the past two decades. Thus, the present study examines monthly counts of deaths from Matlab data for a period 15 years later and tests the hypothesis of a decrease or shift in seasonality over time. METHODS: Trigonometric regression models were fit to monthly data by age and cause of death from the Matlab vital registration system for the years 1982-1990. A total of 20,328 death records were available for analyses. RESULTS: In the recent period significant sinusoidal seasonal patterns are found in all but one of the age and cause of death groups. Total deaths peak in the winter as do neonatal deaths but post-neonatal and child deaths are maximum in April and July respectively. Among cause groups, injury deaths (mostly attributed to drowning) show the greatest seasonal swing. The time of peak has only shifted for one age group--neonates--since the 1972-1974 period. The magnitude of the seasonal swing has declined significantly only for the neonatal age group and injury cause of death group. CONCLUSION: Marked seasonal patterns of deaths persist in the Matlab area of Bangladesh even as the level of mortality has declined.     

秦山核电厂一回路辅助工艺系统调试

本文叙述了秦山核电厂一回路主要调试项目以及在预运运行试验和初始启动试验阶段的实施情况。调试结果表明，系统已具备所要求的功能，运行参数达到了设计要求，能安全、可靠地配合反应堆冷却剂系统，满足各种工况的运行要求。