高地震区公路隧道地震动力响应分析

基于土一结构相互作用理论,对高地震区一实际重大工程的公路隧道洞口段结构进行了抗震计算,得到了衬砌结构各控制点的位移、加速度及内力响应规律。结果表明：在人工合成地震波条件下,衬砌墙脚、拱腰为抗震薄弱位置;结构的加速度波形与输入波形相似;这些结果为抗震设计提供了一些依据。     

地铁隧道结构变形监测信息管理系统的开发

地铁隧道结构变形监测的特殊性、周期性和长期性,使其信息量非常庞大.信息管理是地铁隧道结构变形监测中一项重要的工作,现有的管理方式效率很低.为了高效、准确地管理监测信息,及时分析预报地铁隧道结构的稳定状况,本文结合南京地铁运营期隧道结构变形监测实例,开发了一套具有变形监测资料存储、预处理、管理分析、可视化分析、预测预报及限值预警等功能的信息管理系统,保证了准确及时快速的数据处理和信息反馈,具有良好的运用和推广前景.     

自动化监测技术在我国首条大型电力隧道中的应用

通过自动化监测在超大工程项目中的应用,利用现有技术手段,对工程进行有效管理,逐渐将对工程的安全、预判起到越来越重要的作用,它可以在为工程节约大量资金情况下,提高预判安全施工的能力,是提高工程管理的重要手段。     

Overbreak and underbreak in underground openings Part 2: causes and implications

Summary The newly developed light sectioning method has been used to investigate some of the causes and costs of overbreak and underbreak. Investigations at the Aquamilpa Hydroelectric Project in Mexico have shown decreased overbreak and increased underbreak as a result of increased rock quality and decreased explosive energy. A new measure of explosive energy, the perimeter powder factor (PPF), has been defined and shown to be useful in the context of tunnel-wall rock damage. Tentative results indicate that explosive energy (PPF) may be a more important factor in producing underbreak, whereas rock quality may be a greater factor in producing overbreak. A site-specific equation is given for predicting overbreak or underbreak as a function of rock quality and explosive energy, with an evaluation of the cost of underbreak and overbreak.     

The origin of accretionary lapilli

Experimental investigations in a recirculating wind tunnel of the mechanisms of formation of accretionary lapilli have demonstrated that growth is controlled by collision of liquid-coated particles, due to differences in fall velocities, and binding as a result of surface tension forces and secondary mineral growth. The liquids present on particle surfaces in eruption plumes are acid solutions stable at 100% relative humidity, from which secondary minerals, e.g. calcium sulphate and sodium chloride, precipitate prior to impact of accretionary lapilli with the ground. Concentric grain-size zones within accretionary lapilli build up due to differences in the supply of particular particle sizes during aggregate growth. Accretionary lapilli do not evolve by scavenging of particles by liquid drops followed by evaporation — a process which, in wind tunnel experiments, generates horizontally layered hemispherical aggregates. Size analysis of particles in the wind tunnel air stream and particles adhering to growing aggregates demonstrate that the aggregation coefficient is highly grain-size dependent. Theoretical simulation of accretionary lapilli growth in eruption plumes predicts maximum sizes in the range 0.7–20 mm for ash cloud thicknesses of 0.5–10 km respectively.     

钻孔灌注桩施工对邻近运营隧道变形影响研究

桩基施工将引起周边地层位移和邻近隧道结构变形,以南京龙津桥改建项目桩基工程为背景,通过现场实测,分析研究钻孔灌注桩施工全过程各工况条件对地层位移场和邻近既有隧道结构变形的影响规律。结果表明:由于钢套管的护壁作用,钻孔灌注桩施工过程中产生的最大地层位移和隧道结构变形较小,说明采用“钢套管边旋压边取土”、“群桩间跳施工”等工艺,对周围土体扰动影响程度较小,建议近隧桩基工程采用全套管灌注桩的施工方法,监测分析结果可为类似工程提供技术参考。     

云南元-磨公路某高堑坡灾害发生机制及防治对策

论文根据现场地质调查,应用地质力学分析方法,分析了元-磨公路K235 160~600段高堑坡地质条件、病害发生机制和诱发因素。堑坡所在区域位于红河深大断裂与哀牢山深大断裂所夹持的哀牢山褶皱带内,属强烈侵蚀切割的低中山区,河流下切严重,河流阶地不发育。南溪河及其支流小曼萨河、叉河依附于不同时期生成的构造发育而成,堑坡位于小曼萨河注入南溪河的交汇部位小曼萨河的左岸。小曼萨河及南溪河所夹持的山体,尤其是堑坡所在的部位,已严重破碎、松弛,岩石似大块石堆垒状,坡面上的树木均明显地向小曼萨河方向倾倒。经地质力学配套分析,堑坡所依附的山梁形成于红河深大断裂生成期(γ4),堑坡岩体受多期构造活动的作用,其中NW65/°SW64°及NW63/°SW35°两组倾向临空的构造面控制坡体的稳定。堑坡具备发生变形破坏的地质条件,分析认为由于组成坡体的岩土强度不足而引起既有构造面的大型坍塌。连续降雨及温差是诱发因素。基于目前国内边坡防治技术、施工能力,提出了以“治”或“避”为主的防治对策。     

小岩头滑坡稳定性分析

小岩头滑坡位于贵州省威宁县二(连浩特)河(口)高速公路K255 010~K255 240里程右侧,属一个大型古滑坡,发育于二叠系上统峨嵋山组玄武岩(P2β)地层中。在高速公路施工中对路堑进行深挖削坡,可能导致古滑坡中部、线路右侧斜坡失稳破坏,发生滑坡。因此,滑坡稳定性评价是重大工程地质问题之一。根据大量勘察试验资料,系统地揭示了滑坡的特征,分析了滑坡形成的控制因素、成因和形成机制,建立了滑坡体稳定性计算模型,利用反演计算法进行稳定性分析与评价,认为两滑体均处于滑动失稳状态。建议对滑坡体进行处理,采用排水、支挡、减压等措施进行整治。     

Construction techniques for the Taklamakan Desert Highway: research on the construction materials and the results of field tests

After conducting many laboratory and field experiments, several key technical issues related to the construction of China’s Taklamakan Desert Highway have been satisfactorily resolved. In particular, considerable progress has been made on the dry compaction of a sand sub-base, road design parameters, the creation of a structure that combines a sub-grade and asphalt pavement, analysis of the stability of a sand sub-base strengthened with geotextiles, and on the development of a complete set of construction techniques. The achievements of this research were successfully applied for the first time in the Taklamakan Desert, where the environmental conditions are extremely harsh. The results suggest that the construction of this highway was economical and that the simple construction methods produced a reliable highway. The resulting highway is believed to be the world’s first long-distance graded highway running through a huge desert with migrating dunes.