云覆盖对流边界层顶部湍流结构参数的研究

应用飞机探测资料分析研究云覆盖对流边界层顶部温度和湿度湍流结构,在考虑对流边界层顶部夹卷过程的基础上得到计算温度和湿度结构参数的公式。应用实际观测资料分析了云覆盖对流边界层顶部的湍流特征．资料分析表明,云外晴空区温度和湿度结构函数值明显高于云内的值．云顶边界清晰,通过界面温度和湿度具有明显的跃变特征．应用观测资料检验了温度和湿度结构参数计算公式,计算结果与观测结果符合较好．     

拟合后剩余残差的统计检验与待估参数的选择

在空间技术的实际资料处理中,经常遇到不同待估参数组合解算的ＲＭＳ水平大致相当而估值结果相差甚远的情况．本文提出采用残差统计检验的方法,结合ＲＭＳ的大小,来判断精密定轨和参数解算的好坏．将拟合后的剩余残差序列看作一个随机变量样本,并假设其满足正态分布,采用高阶矩和皮尔逊χ２ 统计量来度量残差序列偏离正态分布的程度．根据统计检验的结果,提出选择合适的待估参数的标准     

Towards probabilistic seismic performance of vehicle-bridge interaction systems: From stochastic dynamic model to fragility analysis

This paper aims to assess the seismic fragility of vehicle-bridge-interaction (VBI) systems considering the effects of vehicle types, traffic conditions, and road surface qualities. A stochastic nonlinear mechanical model for the earthquake-VBI system is developed, and the fragility functions for the proposed VBI model are derived by considering the relevant probabilistic seismic demand parameters. On the basis of a typical four-span continuous prestressed concrete highway bridge in China, a complete numerical model for the VBI system is built considering multiple uncertainties from bridge and vehicle parameters, as well as the road surface qualities. A total of 120 real ground motion records with different combinations of magnitude-source-to-site distance (M-R) and earthquake intensity characteristics are selected. Meanwhile, 80 scenarios in terms of different combinations of vehicle types, vehicle speeds, and road surface irregularities are defined. In this context, 96,000 nonlinear time-history analyses are performed, and the developed fragility models are applied to the VBI system at both component and system levels. Results indicate that the fragilities of pier drift, bearing shear strain, and the overall VBI system increase with the increase of the vehicle weight or the decrease of the vehicle speed, while the vertical deck displacement is dominated by the vehicle weight. It is also found that the road surface quality has a negligible effect on both component and system fragilities.     

两种激光粒度仪测量结果的对比

用两种型号(Cilas 940L和Malvern2000)的激光粒度仪对149个沉积物样品进行了测量,对测量结果作了对比分析。包括各粒级间的对比、各种粒度参数的对比以及相关分析等。找出了两种仪器在不同粒级之间的差异和相关性。分析结果表明,两种仪器的分析数据在13～14pm的粒度区间最为接近,小于此粒级范围时Cilas 940L所测得数据大于同粒级内Malvern2000的观测值,大于此粒级范围的分析结果则相反,即Cilas 940L对细粒样品的敏感性更强一些。     

Crystallinity and metamorphism of illite from Triassic strata in Henan County of Qinghai Province

In order to verify the Triassic stratum metamorphism in this area, the crystallinity of illite in mudstone (shale) of Triassic stratum was analyzed and tested during the 1:50 000 regional mineral geological survey (I47E007023, I47E008023, I47E009023,1I47E009024)in Tuoyema area of Henan Mongolian Autonomous County in Qinghai Province. According to the experimental results of 30 samples, the crystallinity index of Triassic mudstone (shale) illite Kübler in Zongwulong-Zeku stratigraphic division in the north is 0.312-0.537, and the cell parameter b₀ is 0.898-0.903 2 nm. The metamorphic temperature is less than 350 ℃, with the grape-chlorite and zeolite facies. The crystallinity index of Triassic mudstone (shale) illite Kübler in the western inclined mountain stratigraphic division in the south is 0.21-0.318, and the b₀ value is 0.898 1-0.901 4 nm. The metamorphic temperature is mainly between 200 and 350 ℃, with the local temperature above 350 ℃ and grape-chlorite and greenschist facies. It is considered that the regional metamorphism grade in this area is very low or has no regional metamorphism. The metamorphism degree of the western dipping mountain stratum in the south is slightly higher than that of Zongwulong-Zeku stratum in the north. The measured metamorphic facies belts are not consistent with the previous thought, that is "regional low temperature dynamic metamorphism and low greenschist facies metamorphic belts", and the degree of metamorphism is relatively lower. It is confirmed that there is no large area regional metamorphism in the Triassic strata of Henan County in Qinghai Province, but only very low-level regional metamorphism.     

抽水试验中两种直线图解法的对比

应用定流量非稳定流抽水试验获取含水层水文地质参数时,常用的求解方法是Jacob直线图解法,而拟合直线的方法一般是基于最小二乘理论,但该方法易受异常值影响,拟合结果常常不理想,从而导致求解的参数值误差较大.相比最小二乘法,基于信息损失最小化的最频值算法对异常值不敏感,是一种更为稳健的算法.将最频值算法与Jacob直线图解...     

缺资料流域水文模型参数区域化研究进展

缺资料流域由于缺乏历史径流资料无法进行水文模型参数率定,因此模型参数识别具有很大的难度和不确定性。目前国内外学者对缺资料流域水文模型参数识别一般采用区域化方法,即通过某种途径,利用有资料流域的模型参数推求缺资料流域的模型参数,从而对缺资料流域进行预报。文章总结分析了缺资料流域水文模型参数区域化方法中的参数移植法和回归法的研究进展,对存在的方法选择问题、尺度问题等进行了讨论,并指出在参数不确定性、尺度转换以及多种信息源利用等方面还有待于进一步研究。     

特小流域洪水计算概论

根据特小流域的雨洪特性，分别概论了特小流域设计洪峰流量计算、设计洪水过程线确定、方法（公式）选用与成果合理性分析等。特别提出了不管采用哪种方法（公式）计算设计洪峰流量，均需对特小流域进行水文查勘，并尽量利用实测资料，对各项参数进行分析和检验，使计算成果更符合实际情况。     

岩石抗剪强度参数的理论概率分布形态研究

岩石抗剪强度参数的概率分布形态是岩石工程可靠度分析和设计的基础。在考虑完整岩石压缩强度为服从正态分布随机变量的条件下,针对Mohr-Coulomb和Drucker-Prager屈服准则的线性系数形式,基于随机变量函数分布理论推导出岩石抗剪强度参数内摩擦角 和黏聚力 的概率密度函数。 和 概率密度函数显示：不仅岩石压缩强度和抗剪强度参数概率分布具有非一致性,而且根据不同屈服准则计算得出的岩石抗剪强度参数概率分布也具有非一致性。在进一步分析屈服准则系数具有不同变异系数和相关系数时的抗剪强度参数概率密度函数特征的基础上,提出根据概率分布的偏度和峰度确定一般情况下抗剪强度参数概率分布形态的方法,从理论上解决岩石压缩强度与抗剪强度参数分布的协调性问题。最后,对大理岩常规三轴压缩试验得出的抗剪强度参数进行大样本统计分析,验证了其概率密度函数理论推导的正确性以及概率分布形态确定方法的合理性。该研究为实际岩石强度概率分析时选择抗剪强度参数合理概率分布形式提供了理论指导。     

煤矿巷道锚杆支护的参数优化

目前煤矿巷道锚杆支护设计尚存在不足,造成锚杆锚固能力未能充分发挥,支护材料浪费和支护成本偏高。基于围岩与锚杆共同作用原理,通过锚杆受力监测,对锚杆支护参数进行设计,有助于充分发挥锚杆支护的优越性。针对陕西某煤矿巷道条件,通过计算和锚杆受力监测,调整锚杆参数的方法,进行锚杆支护参数设计,实现锚杆支护的参数优化。应用结果表明利用这一方法能够准确、快速地得到锚杆的支护参数,充分发挥了支护锚杆的承载能力,实现了支护优化。本文工作对改进煤矿巷道支护设计具有一定的实际意义和工程价值。