沱沱河盆地古近纪-新近纪盆地演化及青藏高原隆升的沉积响应   总被引：3，自引：0，他引：3       下载免费PDF全文

刘燕学  侯增谦  王光辉  江小均  李政  宋玉财  王晓虎 《地学前缘》2011,18(4):65-76

通过对青藏高原腹地沱沱河盆地古近纪-新近纪沉积序列、区域不整合面、岩性特点及分布特征等分析研究,认为沱沱河盆地古近纪-新近纪沉积由下而上可分为沱沱河组、雅西措组、五道梁组和曲果组4个向上变浅序列,构成两个完整的陆相造山磨拉石建造序列.盆地分析表明,古近纪-新近纪沱沱河盆地经历了前陆盆地演化阶段(56.5～45.0 Ma...  相似文献   

软岩巷道锚网索联合支护设计及支护效果分析     

张向东  张虎伟  阮剑剑 《中国地质灾害与防治学报》2011,22(3):67-73

软岩巷道围岩松散破碎承载力低,在工程荷载作用下,具有明显的塑性变形和强流变性。传统单一的支护手段难以保证其安全和稳定。高家梁煤矿2-2上煤层巷道是典型的软岩巷道,其围岩遇水泥化、膨胀、崩解,进而造成巷道出现断面收缩、片帮、冒顶等失稳现象。针对高家梁煤矿2-2上煤层20110综采工作面回风顺槽的软岩问题,结合该巷道具体工程地质条件及围岩物理力学特性设计出锚网索联合支护的方案。通过FLAC3D数值模拟分析及现场巷道围岩表面位移监测,对该方案的支护效果进行了分析,其结果证明了该联合支护方案可以有效的控制膨胀型软岩巷道的稳定性,从而保证了煤矿的安全生产。  相似文献   

岩溶地区隧道施工综合预报技术案例分析     

刘智  邓辉  黄润秋  黄艾  刘海军 《中国地质灾害与防治学报》2011,22(4):74-80

由于岩溶地区隧道地质条件的复杂性,在隧道施工过程中实施准确及时的隧道综合地质超前预报是非常有必要的,并且对隧道内不同段落进行风险评价和风险分级,以实现和提高对岩溶隧道不良地质灾害的综合预报。此次研究以伊家岩隧道为工程背景,通过严格实施该综合超前地质预报方案,成功预报了隧道掌子面前方的岩溶,结合预报结果和实际揭露的对比分析,其综合预报准确率可到90%以上,证实了该综合预报方法具有较高的系统性和工作效率,有效地指导了隧道的安全施工,为同类工程提供了技术资料和经验。  相似文献   

改进的地震模型初值射线追踪方法     

贺中银  高阳 《中国煤炭地质》2011,(5):42-44

初值射线追踪方法是现代射线追踪方法中的一个很重要的理论,它克服了两点法射线追踪方法耗时的计算效率问题。以程函方程为基础,对初值射线追踪方法进行改进,即利用平方慢度来替换模型中的速度参数,使得程函方程产生解析解,从而进一步导出当射线遇到界面时的反射和透射慢度向量的计算表达式,以及反射、透射系数的函数表达式。通过对简单的两层界面向斜模型及复杂的多层盐丘模型的射线追踪,表明该初值射线追踪方法的改进相比于以往的龙格库塔离散数值解法,不但使射线追踪效率得到了大幅度提高（10倍左右）,且也扩大了射线法使用范围。  相似文献   

Uncertainty in Tropical Cyclone Intensity Predictions due to Uncertainty in Initial Conditions     

Chenxi WANG  Zhihua ZENG  Ming YING 《大气科学进展》2020,37(3):278-290

Focusing on the role of initial condition uncertainty,we use WRF initial perturbation ensemble forecasts to investigate the uncertainty in intensity forecasts of Tropical Cyclone(TC)Rammasun(1409),which is the strongest TC to have made landfall in China during the past 50 years.Forecast results indicate that initial condition uncertainty leads to TC forecast uncertainty,particularly for TC intensity.This uncertainty increases with forecast time,with a more rapid and significant increase after 24 h.The predicted TC develops slowly before 24 h,and at this stage the TC in the member forecasting the strongest final TC is not the strongest among all members.However,after 24 h,the TC in this member strengthens much more than that the TC in other members.The variations in convective instability,precipitation,surface upward heat flux,and surface upward water vapor flux show similar characteristics to the variation in TC intensity,and there is a strong correlation between TC intensity and both the surface upward heat flux and the surface upward water vapor flux.The initial condition differences that result in the maximum intensity difference are smaller than the errors in the analysis system.Differences in initial humidity,and to a lesser extent initial temperature differences,at the surface and at lower heights are the key factors leading to differences in the forecasted TC intensity.These differences in initial humidity and temperature relate to both the overall values and distribution of these parameters.  相似文献   

GRAPES全球/区域集合预报系统10年发展回顾及展望     

陈静  李晓莉 《气象科学进展》2020,10(2):9-18,29

较系统地概述了中国气象局全球/区域集合预报系统及描述模式初值和模式自身不确定性的集合预报扰动技术发展历程,回顾了GRAPES(Global/Regional Assimilation Pr Ediction System)全球集合预报的奇异向量初值扰动方法、GRAPES区域集合预报的集合变换卡尔曼滤波初值扰动方法和多尺度混合初值扰动方法、GRAPES全球/区域集合预报模式不确定性的随机物理过程倾向项扰动方法和动能后向散射随机补偿方法等研究成果,介绍了GRAPES全球/区域集合预报业务系统构建参数设置和预报性能,最后分析了GRAPES全球/区域集合预报中存在的问题,展望了未来发展方向。  相似文献   

Using the Lund-Potsdam-Jena Model to Understand the Different Responses of Three Woody Plants to Land Use in China     

SUN Guodong  MU Mu 《大气科学进展》2013,30(2):515-524

In this study, the approach of conditional nonlinear optimal perturbation related to initial perturbation (CNOP-I) was employed to investigate the maximum variations in plant amount for three main woody plants (a temperate broadleaved evergreen, a temperate broadleaved summergreen, and a boreal needleleaved evergreen) in China. The investigation was conducted within a certain range of land use intensity using a state-of-the-art Lund-Potsdam-Jena dynamic global vegetation model (LPJ DGVM). CNOP-I represents a class of deforestation and can be considered a type of land use with respect to the initial perturbation. When deforestation denoted by the CNOP-I has the same intensity for all three plants, the variation in plant amount of the boreal needleleaved evergreen in northern China is greater than the variation in plant amount of both the temperate broadleaved evergreen and temperate broadleaved summergreen in southern China. As deforestation intensity increases, the plant amount variation in the three woody plant functional types carbon changes, in a nonlinear fashion. The impact of land use on plant functional types is minor because the interaction between climate condition and land use is not considered in the LPJ model. Finally, the different impacts of deforestation on net primary production of the three plant functional types were analyzed by modeling gross primary production and autotrophic respiration. Our results suggest that the CNOP-I approach is a useful tool for exploring the nonlinear and different responses of terrestrial ecosystems to land use.  相似文献   

Horizontal freezing study for cross passage of river-crossing tunnel     

Ming Zhang  LingMin Wang  BaoWen Wang  HongBao Lin 《寒旱区科学》2011,3(4):0314-0318

To determine the appropriate soft foundation treatment for a river-crossing tunnel, freezing reinforcement design and technology were introduced based on the channel tunnel design and construction practice. Through finite element analysis and engineering practices, two rows of horizontal perforated freezing pipes were designed and installed on both sides of a passage for tunnel reinforcement, which produced the thickness and strength of frozen crust that satisfied the design requirements. These information are valuable for guiding the design and construction of river-crossing tunnels in coastal areas.  相似文献   

一种适用于长弧段的初轨计算方法   总被引：3，自引：3，他引：0  

陆本魁  马静远  夏益  张晹 《天文学报》2003,44(4):369-374

根据单位矢量法测轨原理，在人造卫星初轨计算的单位矢量法基础上，给出了一种适用于长弧段的初轨计算方法．该方法既适用于长弧段，也适用于短弧段；适用于各种不同类型的观测资料和任意偏心率、任意轨道倾角的人造地球卫星；有利于提高初轨测定精度；并改善整个计算收敛性．特别需要指出的是，该方法与有摄初轨计算的单位矢量法相结合，为单位矢量法从初轨计算推广到轨道改进打下了坚实的基础．  相似文献   

超长隧洞施工测量若干问题研究     

王腾军  田青文 《地球科学与环境学报》2003,25(2):66-69

超长隧洞施工测量属于超规范作业,为保证超长隧洞贯通,必须对超长隧洞施工测量进行研究。对隧洞施工测量中洞口控制网布设、数据处理及其误差对贯通的影响与洞内基本控制网的布设、平差及检核方法等若干问题进行了研究,所得成果已运用于引黄入晋工程中的南干5#和7#超长隧洞施工测量中,确保了两超长隧洞的顺利贯通。  相似文献