掺砂率对膨润土与砂混合物膨胀特性的影响

膨润土与砂混合物的膨胀特性是评估核废料深层地质处置工程长期性能的重要指标。对比不同膨润土及其与砂混合物的膨胀试验结果可知,对纯膨润土及其低掺砂率混合物,浸水膨胀完成后蒙脱石孔隙比em与竖向应力?v在双对数坐标内呈惟一的线性关系,利用该线性关系可预测浸水完成后不同竖向应力下的体积变化量及不同初始状态对应的膨胀力;对高掺砂率混合物,在砂骨架形成之前,em-?v线性关系成立,随着竖向应力的增大,砂骨架形成,对应的em值脱离em-?v线性关系,混合物中掺砂率越大,脱离该线性关系时的竖向应力就越小。砂骨架形成前,砂颗粒被蒙脱石包围,外力由蒙脱石承担,最终变形量由试样中单位体积蒙脱石的含量决定;砂骨架形成后,竖向应力最终由砂骨架和蒙脱石共同承担。利用砂骨架孔隙比的概念可确定各种不同掺砂率混合物形成砂骨架时的应力起偏点。同时,还可确定混合物能够形成砂骨架的掺砂率范围。     

全无缝桥梁接线路面拉伸力学特性理论和实验研究

为了掌握和模拟全无缝桥梁接线路面弹塑性拉伸特性,本文基于钢筋和混凝土的单轴拉伸平均应力-应变本构模型,推导出接线路面的宏观弹塑性拉伸P-Δ理论模型;并对室内总长28 m的接线路面足尺模型,进行了拉伸试验。结果显示:(1)接线路面的理论与实验拉伸P-Δ骨架曲线在钢筋屈服前后都吻合得很好,可以直接用于全无缝桥梁抗震设计和损伤评估;(2)接线路面实验模型的拉伸变形量Δ高达14 cm时,仍未拉断,其延性甚好、有利于抗震。     

一种改进的图斑合并算法

从计算几何的角度提出了一种改进的图斑合并(聚合和融合)方法。图斑聚合采用缓冲区合并的思想,可以有效地合并"桥梁"区域,并保持图斑的自然弯曲形态;图斑融合通过骨架线剖分小图斑,以共享边和地类为共同作用因子,将小图斑逐个合并到原始图斑的拓扑相邻图斑中。此算法有效地维持了图斑边界的自然弯曲,并顾及了图上显示地类的父类整体变化情况。     

Undrained Cyclic Pore Pressure Response of Sand–Silt Mixtures: Effect of Nonplastic Fines and Other Parameters

Literature regarding the pore pressure generation characteristics and in turn the cyclic resistance behaviour of silty sand deposits is confusing. In an attempt to clarify the effect of nonplastic fines on undrained cyclic pore pressure response of sand–silt mixtures, an experimental programme utilising around 289 stress-controlled cyclic triaxial tests on specimens of size 50 mm diameter and 100 mm height was carried out at a frequency of 0.1 Hz. Specimens were prepared to various measures of density through constant gross void ratio approach, constant relative density approach, constant sand skeleton void ratio approach, and constant interfine void ratio approach to study the effect of nonplastic fines on pore pressure response of sand–silt mixtures. The effect of relative density, confining pressure as well as the frequency and magnitude of cyclic loading was also studied. It was observed that the pore pressure response is greatly influenced by the limiting silt content and the relative density of a specimen corresponding to any approach. The influence of other parameters such as relative density, confining pressure and magnitude of cyclic loading was as usual but an increase in frequency of cyclic loading was seen to generate excess pore pressure at a higher rate indicating an impact load type of behaviour at higher frequency. Utilising the entire test results over a wide range of parameters a new pore pressure band for sand–silt mixtures in line with Lee and Albaisa (1974) has been proposed. Similarly another pore pressure band corresponding to 10th cycle of loading as suggested by Dobry (1985) and up to a shear strain of around 25% has been proposed. These two bands can readily be used by researchers and field engineers to readily assess the pore pressure response of sand–silt mixtures.     

甘肃穿心河碳酸盐岩型纤维状海泡石矿赋矿特征及矿床工业意义

本文通过对甘肃穿心河碳酸盐岩型纤维状海泡石矿的成矿地质背景分析。论述了矿物岩石特征和控矿地质条件,总结了矿床成因及找矿标志,对其工业意义和经济评价作了概略说明。     

含砾量对饱和砂-砾混合料排水剪切强度的影响

为探讨含砾量Gc对砂-砾混合料排水剪切强度Sd的影响,对砂-砾混合料开展了一系列三轴排水试验。结果表明,Gc不同的混合料的应力-应变关系曲线呈应变硬化型和应变软化型2种不同的发展模式,随着Gc的增加,无论砂-砾混合料处于松散(Dr=0.2)、中密(Dr=0.4、0.6)还是密实(Dr=0.8)状态,排水剪切强度Sd均先略有降低后保持不变,最后迅速增加。研究发现,e、Cu、Cc和d50都不能作为合理描述不同Gc的砂-砾混合料Sd的参数,而具有不同Gc和Dr的砾-砂混合料的Sd均随等效骨架孔隙比esk的增大而降低,表明esk可以合理地表征砂-砾混合料Sd的物理状态。     

DEM数据辅助的山脊线和山谷线提取方法的研究

从数字化地形资料中自动提取山脊线和山谷线的技术在测绘、工程设计等方面有着重要的意义。本文对现有的山脊线和山谷线自动提取的方法进行深入研究后 ,指出充分利用数据中所含有的地形信息是正确提取山脊线和山谷线的有效途径 ,那种试图仅依靠二维等高线形态分析的方法很难得到理想的结果。依照该思想本文设计出了一种基于DEM数据辅助的山脊线和山谷线提取方法。该方法先利用等高线数据建立区域地形概略DEM ,然后借助三维地形分析的技术辅助进行山脊线和山谷线的提取。文后通过实验验证了该方法的有效性 ,它所提取的山脊线和山谷线与实际地形相符合。     

Numerical analysis on dynamic deformation mechanism of soils under blast loading

Soil is considered as a three-phase medium consisting of solid particles, water and air. Its behavior is very difficult to predict, especially under high rate blast loading. In this study, a new three-phase soil model for shock loading is employed to facilitate a full simulation of explosion and the subsequent stress wave propagation in soils. Upon validating the model, extended numerical calculations are carried out and the results are analyzed to demonstrate the change of characteristic parameters of the soils, the inherent distribution of the pressure on individual phases and hence the deformation mechanisms of the soils under blasting loading. Two primary deformation mechanisms exist, one is the deformation of the soil skeleton formed by the solid particles; the other is the deformation of all individual soil phases. It is found that the response of soil near the charge is dominated by the second mechanism while the first mechanism dominates in areas beyond a certain scaled range. The location of the transition zone depends primarily on the initial state of the soil. The results are useful for establishing rational and practical soil models for engineering applications concerning blasting.     

长刺泡沫状珊瑚(Gyalophylloides Cao 1975)属骨骼微细构造的电镜研究

Gyalophylloides Cao 1975属的电镜研究表明,其骨骼构造以方解石晶片组成的层状骨骼为主,它形成壁部构造和横列构造,在隔壁之间充填联结,在隔壁内包绕隔壁刺,在隔壁刺内联结和包绕杆状体。本属纤状骨骼的组成单元是晶粒和短轴晶柱,它们只见于杆状体轴部。文中还描述了本属的两个新种。     

小比例尺地图面状水系名称注记自动配置研究

在丰富面状水系的注记配置规则基础上,深入研究了其名称注记自动配置中两个关键算法,即要素主骨架线求取和注记配置方案的设计,并提出了基于单调链化简思想确定面状水系主骨架线的改进算法,在此基础上设计了面状水系名称注记自动配置方案。