Hyperstatic reaction method for calculations of tunnels with horseshoe-shaped cross-section under the impact of earthquakes

Tunnels are now an integral part of the infrastructure in major cities around the world. For many reasons, these tunnels have horseshoe-shaped cross-sections with round top and flat bottom. This paper presents some improvements to the use of the Hyperstatic Reaction Method-HRM for analysing tunnels with horseshoe-shaped cross-sections when these tunnels operate under the influence of earthquakes, particularly in cases when the tunnel lining is a continuous lining. The analysis used parameters of a tunnel from the Hanoi metro system, as well as parameters of the strongest earthquake that may occur in the central Hanoi area in the improved HRM and 2 D numerical methods using the ABAQUS software. On the basis of the results obtained, the paper gives conclusions about the HRM methodology when it is used to calculate tunnels that have horseshoe cross-sections operating under the influence of earthquakes.     

Application of GIS to Geo-anomaly-Based Delineation of Mineral Resources

The geo-anomaly-based delineation of mineral resourcesusing GIS (Zhao et al.,1 996,1 995;Zhao and Chi,1 991 )takes the geological anomalous ore-forming theory as its theo-retical basis,the conceptual model of geology and mineral re-sources and the corresponding spatial analysis model as its ge-ological foundation,the GIS as its basic tool for the analysisof mineral resources prediction,and the analyses of favorableprospecting index and the spatial correlation of geologicalanomalies assemblag…     

RELATION BETWEEN RAPID UPLIFTING AND GRAVITATIONAL EQUILIBRIUM ,TECTONICS AND THERMODYNAMIC EFFECT IN QINGHAI—TIBET PLATEAU

RELATION BETWEEN RAPID UPLIFTING AND GRAVITATIONAL EQUILIBRIUM ,TECTONICS AND THERMODYNAMIC EFFECT IN QINGHAI—TIBET PLATEAU     

Kaitianite,Ti3+2Ti4+O5, a new titanium oxide mineral from Allende

Kaitianite, Ti³⁺₂Ti⁴⁺O₅, is a new titanium oxide mineral discovered in the Allende CV3 carbonaceous chondrite. The type grain coexists with tistarite (Ti₂O₃) and rutile. Corundum, xifengite, mullite, osbornite, and a new Ti,Al,Zr‐oxide mineral are also present, although not in contact. The chemical composition of type kaitianite is (wt%) Ti₂O₃ 56.55, TiO₂ 39.29, Al₂O₃ 1.18, MgO 1.39, FeO 0.59, V₂O₃ 0.08 (sum 99.07), yielding an empirical formula of (Ti³⁺_1.75Al_0.05Ti⁴⁺_0.10Mg_0.08Fe_0.02)(Ti⁴⁺_1.00)O₅, with Ti³⁺ and Ti⁴⁺ partitioned, assuming a stoichiometry of three cations and five oxygen anions pfu. The end‐member formula is Ti³⁺₂Ti⁴⁺O₅. Kaitianite is the natural form of γ‐Ti₃O₅ with space group C2/c and cell parameters a = 10.115 Å, b = 5.074 Å, c = 7.182 Å, β = 112°, V = 341.77 Å³, and Z = 4. Both the type kaitianite and associated rutile likely formed as oxidation products of tistarite at temperatures below 1200 K, but this oxidation event could have been in a very reducing environment, even more reducing than a gas of solar composition. Based on experimental data on the solubility of Ti³⁺ in equilibrium with corundum from the literature, the absence of tistarite in or on Ti³⁺‐rich corundum (0.27–1.45 mol% Ti₂O₃) suggests that these grains formed at higher temperatures than the kaitianite (>1579–1696 K, depending on the Ti concentration). The absence of rutile or kaitianite in or on corundum suggests that any exposure to the oxidizing environment producing kaitianite in tistarite was too short to cause the precipitation of Ti‐oxides in or on associated corundum.     

藏北新生代火山作用的时空演化与高原隆升

本文通过对藏北新生代火山岩的岩石化学和同位素年龄资料的综合分析,系统确定了火山岩的岩石系列组合及其生成时序。根据岩石系列的时空演化规律将藏北新生代火山活动划分为3个构造—岩浆亚旋回,火山活动自南向北依次形成羌塘(44～24 Ma)、中昆仑—可可西里(19～7 Ma)、西昆仑—玉门(约5 Ma以来)3条火山岩亚带。各岩带分别以高钾钙碱性或钾玄岩系列构成火山活动的主体, 以碱性钾质火山活动而结束。构造—火山旋回与高原脉动隆升具有明显的耦合性,旋回间歇期与高原夷平期相对应。笔者认为这一火山作用规律是高原每次脉动隆升过程中,构造性质由挤压、增厚,向伸展滑移转化的结果,火山作用旋回受岩石圈水平挤压、增厚和深部地幔热物质沿构造薄弱带挤压上升两种作用的相互消长所制约。     

直立防波堤振动──滑移运动分析的模型和方法

建立了一个动力系统模型及相应分析方法,对破碎波冲击作用下直立式防波堤的振动-滑移运动过程进行数值模拟,预测特殊波浪力作用下防波堤可能出现的滑移量.用本文模型和方法对一沉箱防波堤在破碎波作用下的运动过程进行了计算,并分析了沿基床顶面的滑移对沉箱位移、摇摆角、滑移力和倾覆力矩的影响.     

对样品含水结构的电阻率CT研究

采用高密度的电极阵列,对具含水结构样品的视电阻率值进行了测定,并重建了二维电阻率的图象．所得一系列CT图象揭示了样品内部由于裂隙和流体造成的真电阻率分布及其变化．这一方法用于岩石电性模拟实验,使导致样品电性变化的裂隙充水过程得以清楚地揭示．      

春秋季层状云降水过程Z-I关系计算与讨论

运用最优化方法,按天气系统、降水过程计算层状云降水过程Ｚ－Ｉ关系序列。然后用每 关系得到降雨的雷达估计值,与雨量计实测降雨量比较,对雷达测量降水精度问题进行探讨。     

Analytical solution of water table fluctuations above an inclined leaky layer due to ditch recharge

Ditch recharge is a method used for raising a water table. However, if the aquifer lies above a leaky layer, then the leaky bed will have an effect on the height of the water table. This paper attempts to provide an analytical solution of the transient state to the linearized Boussinesq equation. The solution proposed in this paper is intended for a generalized form of the leaky layer, with the boundary condition of the water level moving according to an exponential form. The results of theoretical analysis and experimental studies can provide a much better explanation of ditch recharge on an inclined leaky layer. Copyright © 2006 John Wiley & Sons, Ltd.     

The effects of self-gravity on the solar nebula

We study the distribution and transport of angular momentum in a self-gravitating accretion disk formed during the collapse of a rotating gas cloud. Using the surface density for the low-viscosity models and minimum-mass models presented by Cassen and Summers, Poisson's equation is solved explicitly to determine the effects of self-gravitation of the protostellar disk. Analytic expressions for the angular momentum of the central star and other relevant quantities of interest during the formation stage are presented.Paper presented at the IAU Third Asian-Pacific Regional Meeting, held in Kyoto, Japan, between 30 September–6 October, 1984.On leave from the City College of the City University of New York, U.S.A.