钙锰矿的研究进展

钙锰矿是土壤、沉积物及海洋锰结核中常见的以3×3结构为主的一族大隧道构造氧化锰矿物.隧道中存在水分子和阳离子,形貌以片状、针状或纤维状为主.水钠锰矿→布塞尔矿→钙锰矿的转化是钙锰矿形成的一个重要途径.这种转化在常压条件下受体系温度、pH、共存粘土矿物、转化时间以及前驱物布塞尔矿亚结构特点,如层间交换离子类型、浓度、以水合离子形态或与MnO6八面体空穴上方键合的强弱、结晶度、Mn(Ⅲ)的含量与迁移特点等因素影响.钙锰矿独特的结构使其所具有的离子吸附、氧化与催化特性及分子级的隧道空间等有望作为特异的分子筛、二次电池正极材料、有机反应催化荆等在环境科学和材料科学等领域具有广阔的应用前景.     

箱涵顶进工艺在玄武湖水底交通隧道方案中的应用

在玄武湖水底交通隧道筑堤开槽埋管方案中,为确保古城墙的安全,可采用箱涵顶进工艺穿越古城墙基础。介绍了箱涵顶进工艺的结构设计及实用前景。     

水下悬浮隧道结构分析研究进展

长期以来,如何快速跨越广袤的水域一直是世人关注的焦点.在最近几十年里,一种新的跨越海峡、大江、湖泊、水道的交通结构物-水下悬浮隧道吸引了世人的目光.水下悬浮隧道的研究历史虽然短暂,但由于该种结构的新颖性与其独有的优越性与应用潜力,使得世界各国的学者专家为此进行了很多有价值的工作.首先概述水下悬浮隧道的概念、优点及需要研究和解决的关键问题;随后从水下悬浮隧道的隧道管体结构、隧道锚固系统、作用荷载以及锚固基础等几个方面的结构简化模型综述了水下悬浮隧道结构分析的研究现状;最后对水下悬浮隧道的发展方向进行了总结和分析.     

水电工程长隧洞开挖造价问题的探讨

由于水电工程长隧洞受地质条件影响受勘测条件和勘探手段的限制以及施工难度大,变化因素多等原因其开挖造价问题较复杂。因此,在水电工程长隧洞开挖定额项目中应考虑短循环进尺因素,增加按围岩分类的补充调整系数,考虑长隧洞开挖艰难因素,补充洞长增加系数     

Predicting the capability-polar-plots for dynamic positioning systems for offshore platforms using artificial neural networks

As the capability of polar plots becomes better understood, improved dynamic positioning (DP) systems are possible as the control algorithms greatly depend on the accuracy of the aerodynamic and hydrodynamic models. The measurements and estimation of the environmental disturbances have an important role in the optimal design and selection of a DP system for offshore platforms. The main objective of this work is to present a new method of predicting the Capability-Polar-Plots for offshore platforms using the combination of the artificial neural networks (NNs) and the capability polar plots program (CPPP). The estimated results from a case study for a scientific drilling vessel are presented. A trained artificial NN is designed in this work and is able to predict the maximum wind speed at which the DP thrusters are able to maintain the offshore platform in a station-keeping mode in the field site. This prediction for the maximum wind speed will be a helpful tool for DP operators in managing station-keeping for offshore platforms in an emergency situation where the automation of the DP systems is disabled. It is obvious from the obtained results that the developed technique has potential for the estimation of the capability-polar-plots for offshore platforms. This tool would be suitable for DP operators to predict the maximum wind speed and direction in a very short period of time.     

Groundwater chemistry within a plateau neighboring Matsumoto city,Japan

The change in groundwater chemistry along the groundwater flow path in the Matsumoto tunnel vicinity was studied, and the origin of the groundwater and dissoluted substances was determined. The relationship between the concentration of HCO₃ ^–, Ca²⁺, and Na⁺, and CO₂ gas pressure in the groundwater indicated that the HCO₃ ^–, Ca²⁺, and Na⁺ were produced by the reaction of the CO₂ gas in the groundwater and feldspar in the rocks. The relationship between the concentration of NO₃ ^– and the Eh and pH values in the groundwater indicated that in an oxidative condition, ammonia-oxidizing and nitriteoxidizing bacteria used NH₄ ⁺ and produced NO₃ ^– and H⁺, and in a reductive condition, denitrifying bacteria used NO₃ ^– and produced N₂ gas and OH^–. The stable hydrogen and oxygen isotopic ratio in the groundwater and precipitation indicated that the groundwater originated from precipitation that had fallen on the area. The concentration of³H and the stable hydrogen and oxygen isotopic ratios in the groundwater suggested that it has been getting warmer climatically for more than 60 years. The stable carbon isotopic ratio indicated that the HCO₃ ^– in the groundwater, excluding deep well water, originated from CO₂ gas produced by organic matter in the soil. The deep well water, which had a higher concentration of HCO₃ ^– than the other groundwater sampled, was thought to have acquired HCO₃ ^– though contact with rocks. The³⁶Cl/Cl ratio indicated the recharge age of the deep well water sampled at a depth of 760 m at the foot of the plateau was recent.     

地铁隧道盾构掘进导向系统的建立

介绍影响盾构隧道导向的因素。详细阐述地铁隧道盾构施工导向系统数学模型的建立过程,介绍盾构机姿态参数测定的方法,以及影响盾构机姿态参数的因素及其相关改正。在深圳地铁盾构工程的实际应用中,实现隧道的顺利贯通,保证隧道的掘进质量,隧道的贯通精度达到了优良工程的要求。     

轨道交通工程联系测量方法的应用

结合北京城市轨道交通建设中测量的实际经验,通过对联系测量应用实例的介绍和隧道贯通测量数据的统计,对影响隧道工程安全贯通的重要环节一联系测量的方法和手段进行了总结,供测量工作者参考。     

昆仑山隧道冻胀力现场测试及其数据分析

冻胀力是冻土隧道支护结构产生病害的主要原因之一,为掌握多年冻土区昆仑山隧道冻胀力的分布形态以及随温度变化的规律,进行了现场测试研究。研究结果表明,到目前为止昆仑山隧道整个支护结构是安全可靠的;冻胀力随着气温、季节的变化而变化,2004年后其变化基本趋于稳定,实测到的冻胀力最大值为0.3 MPa,分布于围岩与初期支护之间仰拱部位;初期支护与二次衬砌之间的冻胀力很小,二次衬砌支护强度可考虑适当减弱;运用影响线理论绘制出了冻胀力包络图,其为确定作用于支护结构上的最不利荷载提供了一种合理有效的方法。     

四川盆地龙泉山含油气构造浅层天然气对隧道工程危害研究

龙泉山是具备油气生储盖组合的含油气构造,出露侏罗系和白垩系非煤系地层,有7个构造高点,节理裂隙发育,是浅层天然气有利聚集区,沙溪庙组砂岩是浅层天然气主要储层。已建达成铁路炮台山隧道和成-简快速通道龙泉山2#隧道在施工中都出现浅层天然气燃烧和爆炸现象。拟建的成洛大道东延线、成安渝高速公路和成渝客专又将以隧道方式通过龙泉山含油气构造,故研究浅层天然气对隧道危害有重要意义。通过现场8座隧道共20个钻孔天然气浓度测试,发现8座隧道均有浅层天然气显示,天然气最高浓度8.654%,最低浓度0.081%, 8座隧道均受到天然气危害。研究表明,隧道所处构造位置和地层岩性是隧道受浅层天然气危害大小的主要影响因素,隧道离含油气构造高点越近,在穿越裂隙发育的地层时,其钻孔天然气浓度越高,隧道受浅层天然气危害越大。