Determination of allowable subgrade frost heave with the pavement roughness index in numerical analysis

Frost heave is an upward swelling of soil during cryogenic conditions in cold regions. It is caused by the accumulation of ice crystals in subgrade soil, which grow upwards when freezing temperatures penetrate into the subgrade. This study establishes the allowable soil subgrade frost heave based on the roughness standard of asphalt pavement in China, and aims to balance the pavement design and frost heave resistance of subgrades in cold regions. We formulated a mechanical model of pavement supported by the boundary conditions of differential frost heave, based on the elastic layered system theory. The differential soil subgrade frost heave was modeled as a sinusoidal function, and the allowable frost heave and the roughness index were modeled as the displacement boundaries for the top and bottom of the pavement structure. Then the allowable frost heave was back-calculated according to the roughness standard. Numerical results show that the allowable frost heave depends on the pavement structure, material properties, the highway grade, and other factors. In order to ensure that the actual soil subgrade frost heave is lower than the allowable frost heave, pavement structures and materials need to be selected and designed carefully. The numerical method proposed here can be applied to establish the frost heave resistance of subgrade when the pavement structure and materials are determined.     

区域发展规划的人地系统动力学基础

区域发展规划研究的出发点是人地关系地域系统和可持续发展战略 ,人地关系的协调共生是区域发展规划的灵魂。文章依据耗散结构理论的基本观点提出了人地系统协调共生的4种状态 ,重点分析了人地系统组成要素及其相互关系在时空层次上的动态关联方式及动力结构 ,旨在为编制区域发展规划奠定坚实的动力学基础。     

关于GeoMedia Professional坐标系统定义问题的探讨

介绍了GeoMedia Professional软件在油田地面工程数字化工作中的应用,并针对设置工作空间、数据库、特征类的坐标系统时容易混淆的问题,及该问题引起的不同数据库之间的坐标系统不一致,以及一个数据库中个别特征类的坐标系统参数不正确的情况进行了分析,同时总结了操作过程中需要注意的问题及解决方法。     

拉萨城市地下水系统可开采资源评价

本文在青藏铁路区域水文地质调查工作的基础上,以系统理论的基本原理为出发点,利用地下水系统数值模型的运行,来对拉萨城市地下水系统可开采资源进行评价,取得了比较理想的结果.     

Structural damage detection using the optimal weights of the approximating artificial neural networks

This work presents a novel neural network‐based approach to detect structural damage. The proposed approach comprises two steps. The first step, system identification, involves using neural system identification networks (NSINs) to identify the undamaged and damaged states of a structural system. The partial derivatives of the outputs with respect to the inputs of the NSIN, which identifies the system in a certain undamaged or damaged state, have a negligible variation with different system errors. This loosely defined unique property enables these partial derivatives to quantitatively indicate system damage from the model parameters. The second step, structural damage detection, involves using the neural damage detection network (NDDN) to detect the location and extent of the structural damage. The input to the NDDN is taken as the aforementioned partial derivatives of NSIN, and the output of the NDDN identifies the damage level for each member in the structure. Moreover, SDOF and MDOF examples are presented to demonstrate the feasibility of using the proposed method for damage detection of linear structures. Copyright © 2001 John Wiley & Sons, Ltd.     

红河断裂构造带在东南亚的延伸特征及其大地构造意义

根据地质、地貌及地球物理资料分析,探讨展布于云南边陲哀牢山两侧的北西向断裂组成的红河断裂构造带,在东南亚的延伸特征。提出在该延伸带两侧沉积建造、构造活动,地球物理场和大地构造发展上均有显著差异。并进一步探讨该断裂构造带在大地构造上的意义。     

西湖凹陷陆盆冲积体系河道演变规律探讨

西湖凹陷渐新统一中新统陆盆沉积发育了类型丰富的河道沉积,本文根据陆盆充填机制对盆地演化各阶段的控制作用,从沉积层序、沉积构造、岩性组合特征诸方面探讨了盆地演化过程的河道变迁特点。     

A Reliability Based Expert System for Assessment and Mitigation of Landslides Hazard Under Seismic Loading

Different models were developed for evaluating the probabilistic three-dimensional (3-D) stability analysis of earth slopes and embankments under earthquake loading using both the safety factor and the displacement criteria of slope failure.The probabilistic models evaluate the probability of failure under seismic loading considering the different sources of uncertainties involved in the problem. The models also take into consideration the spatial variabilities and correlations of soil properties. The developed models are incorporated in a computer program PTDDSSA.These analysis/design procedures are incorporated within a code named SARETL developed in this study for stability analysis and remediation of earthquake triggered landslides. In addition to the dynamic inertia forces, the system takes into consideration local site effects.The code is capable of assessing the landslide hazard affecting major transportation routes in the event of earthquakes and preparing earthquake induced landslide hazard maps (i.e., maps showing expected displacements and probability of slope/embankments failure) for different earthquake magnitudes and environmental conditions. It can also beused for proposing a mitigation strategy against landslides.     

扬子地台北缘裂谷系金与多金属成矿特征

扬子地台北缘大多数金矿床集中集中在裂谷系古陆隆起内外接触处，经历了复杂的地壳结构演化，形成新的金矿类型和矿化组合，具多源性，以深源为主，浅源次之，再次是陆源，控矿构造含同生构造与封闭聚矿盆地等多种成矿作用的叠加。     

雷电定位系统与人工观测雷暴日数统计比较

为了利用雷电定位系统 (lightning location system,LLS) 资料统计人工观测雷暴日数,采用湖北省2007—2012年LLS监测资料,选取25个气象站为圆心,统计其不同监测半径 (r) 圆区域内LLS监测的雷电日数,并与人工观测雷暴日数进行比较。结果表明:r≤7 km时,LLS监测平均年雷电日数小于人工观测平均年雷暴日数;r≥8 km时, LLS监测平均年雷电日数大于人工观测平均年雷暴日数;r=22 km圆区域内年平均雷电日数可替代最大年雷暴日数。根据r=7 km,r=8 km圆区域内LLS监测的年雷电日数、年平均地闪密度资料,分别采用直接替代法、地闪密度法和该文提出的二元法计算年雷暴日数,结果显示:二元法效果最好。二元法计算的2007—2012年25个站平均年雷暴日数与人工观测相等,平均差异为7.4%;二元法计算的2013年年雷暴日数与人工观测相差0.8 d,平均差异为12.3%。