曹妃甸滨海区浅层地下水腐蚀性评价

浅层地下水对地下建筑具有一定的腐蚀性,影响建筑物安全,沿海地区尤为严重。随着曹妃甸新区城市建设的加快,浅层地下水和土对工程的腐蚀性及对工程结构设计的影响也越来越受到关注。本文对曹妃甸滨海区的地下水腐蚀性数据进行了统计分析,并对地下水的侵蚀性进行了评价,得出曹妃甸滨海区域地下水腐蚀性的规律。浅层地下水对混凝土结构具有弱-强的腐蚀性,自北向南逐渐加重;对混凝土结构中的钢筋普遍具有腐蚀性,对钢结构具有弱-中等腐蚀性,总体向南加重。此研究可以为区内的城市规划和工程建设提供借鉴。     

若羌河水库地下水强腐蚀性原因分析

地下水腐蚀性会影响混凝土结构的耐久性、可靠性,在工程建设中必须引起足够的重视。以新疆若羌河水库为例,该水库坝址区工程地质和水文地质条件勘察结果显示,若羌河的河床地表水对混凝土均无腐蚀性,但基岩裂隙水对混凝土具强腐蚀性。通过对基岩裂隙水产生强腐蚀性的原因、腐蚀性与岩性接触带的关系进行分析,明确了地下水强腐蚀性的根本原因。针对地下水腐蚀性会影响混凝土结构的耐久性、可靠性和建筑物安全性的情况,建议根据地下水的腐蚀性对钢筋混凝土结构采取相应的防腐措施。     

新疆康萨依水库坝址区水文地质问题

康萨依坝址区地下水对普通水泥具硫酸盐型强腐蚀,本文分析了地下水中腐蚀性介质(SO2-4)的来源,预测了水库蓄水后地下水化学成份的变化,并对各水工建筑物区地下水的腐蚀性进行评价。     

海水入侵对地铁地下结构侵蚀性的统计分析

地下水的腐蚀性严重影响地铁的安全运营,正确评价地下水的腐蚀性是解决问题的关键。以深圳地铁11号线为例,对全线30个工点627个地下水水质分析样本进行统计,得到整条线路地下水腐蚀强弱分布状态。结合线路通过区的填海和海水侵入背景进行分析,得出如下结论:具有典型的海水侵入背景下的地下水侵蚀性与海水侵入(包括填海区)范围密切相关,地铁地下结构宜按干湿交替环境进行钢筋腐蚀等级判别。该研究为滨海城市海水入侵区地铁线路地下水腐蚀性评价提供指导。     

软土深层搅拌桩的水泥土抗腐蚀性室内试验

结合深港西部通道填海区深层搅拌桩在滨海地下水环境中施工的需要,对水泥土在自来水、地下水、海水及Na2SO4溶液环境下的抗腐蚀性进行了室内研究,研究表明以纯水泥为固化剂的水泥土在腐蚀性地下水环境中的抗腐蚀性能较差,增加矿渣、粉煤灰的含量,能增强水泥土抗腐蚀性;分析了固化剂中矿渣、粉煤灰掺入量对水泥土抗压强度及抗腐蚀性的影响规律,即固化剂掺入比不变的情况下,用矿渣、粉煤灰替代部分水泥能大幅度提高水泥土的抗压强度,同时改善其抗腐蚀性;得出了抗腐蚀性能良好的水泥土配方,即矿渣、粉煤灰的质量占固化剂的40%～60%,可供同类工程借鉴.     

温州地区浅层软水腐蚀性评价研究

为查明温州地区浅层软水化学特征,准确进行腐蚀性评价,基于对区内219个水样化学分析成果数理统计、腐蚀机理与腐蚀环境的分析,进行工程结构腐蚀性验证调查,修正我国岩土规范地下水腐蚀性评价方法中HCO3-腐蚀性含量界限值,尝试提出了适用于温州地区的腐蚀性评价标准,并进行区域浅层软水综合腐蚀性评价.研究结果表明:研究区浅层软水...     

天水市区地下水对建筑物基础腐蚀性评价

本文对天水市区大量地下水水质资料进行了综合分析和研究,初步找出了各种腐蚀性地下水的形成机理和空间分布规律,提出了建筑物地基的安全防护措施.     

红层区城镇地下水对建筑物基础腐蚀及防治研究--以天水市为例

地下水对建筑物基础腐蚀是发育广泛、速率缓慢的地质灾害,它对红层区城市基础工程危害尤显突出。以天水市的红层区为例,利用长期积累的大量地下水化学资料,探讨了腐蚀性地下水的成因,提出了防治地下水对建筑物基础腐蚀的对策。     

上海某厂区土壤和地下水环境质量评估

对上海某地老厂区土壤和地下水采样、检测,表明土壤重金属元素Cd、As,Pb的含量符合国家《土壤环境质量标准（GB15618-1995）》的一级标准要求,Hg、V、Cu的含量明显受到了污染,Mg、Cd、As、Zn、Pb、Be等金属元素含量水平与本地区的土壤环境背景水平相吻合;地下水中pH、NO3^-,-N,Zn属《地下水质量标准》（GBl4848-93）Ⅰ类,Cl^-和NH3^＋-N属V类,地下水对混凝土无腐蚀性,对钢筋有弱腐蚀性。     

新其满塔里木河大桥环境介质对混凝土的影响

塔里木河流域的环境地质条件决定了区内表层地下水矿化度较高,表层岩土易形成盐溃土。本文分析了表层地下水的矿物成分、盐渍土的分布和盐分,评价了其对混凝土的腐蚀性,提出了相应的处理措施。     

向源潜流侵蚀岩溶作用及其成因机理——以塔河油田早海西风化壳岩溶洞穴层为例

向源潜流侵蚀作用指在海(水)进环境中,由于盆地边缘岩溶斜坡带内陆区的潜水面上升后,潜水面以下地下潜流在相当长时间内仍然在原有的洞穴内流动,由此产生的连续向上(向着地下水流源头)侵蚀作用,其结果是在原有的洞穴层之上形成多旋回的具有`坍塌角砾- 暗河沉积’ 双层结构的塌积层序及纵向上呈加积方式产出的叠积洞穴层,以及由叠积洞穴与原有洞穴连成一体的复合洞穴层。本文以塔河油田早海西风化壳岩溶洞穴层为例,简要地介绍了古岩溶洞穴层的对比方法,展示了塔河地区早海西风化壳岩溶洞穴层对比成果,并通过典型井的洞穴层内部结构解剖分析,阐述了向源潜流侵蚀岩溶作用的成因机理,并探讨了一些相关的主要问题。      

青海德尔尼黄铁矿型铜-钴矿床的氧化带特征探析

德尔尼CuCo矿床的氧化带和次生硫化物富集带是不发育的 ,这与气候、构造、地形、矿石成分、侵蚀时间都有一定的关系。矿区地形陡峻 ,地下水宣泄过速、风化剥蚀速度较快以及CuSO4 溶液的大量流失和少部分下渗则是次生富集带缺失的主要原因。     

Erosion of bentonite particles at the interface of a compacted bentonite and a fractured granite

Compacted bentonite has been considered as a candidate buffer material in the underground repository for the disposal of high-level radioactive waste. An erosion of bentonite particles caused by a groundwater flow at the interface of a compacted bentonite and a fractured granite was studied experimentally under various geochemical conditions. The experimental results showed that bentonite particles could be eroded from a compacted bentonite buffer by a flowing groundwater depending upon the contact time, the flow rate of the groundwater, and the geochemical parameters of the groundwater such as the pH and ionic strength.

A gel formation of the bentonite was observed to be a dominant process in the erosion of bentonite particles although an intrusion of bentonite into a rock fracture also contributed to the erosion. The concentration of the eroded bentonite particles eroded by a flowing groundwater was increased with an increasing flow rate of the groundwater. It was observed from the experiments that the erosion of the bentonite particles was considerably affected by the ionic strength of a groundwater although the effect of the pH was not great within the studied pH range from 7 to 10. An erosion of the bentonite particles in a natural groundwater was also observed to be considerable and the eroded bentonite particles are expected to be stable at the given groundwater condition.

The erosion of the bentonite particles by a flowing groundwater did not significantly reduce the physical stability and thus the performance of a compacted bentonite buffer. However, it is expected that an erosion of the bentonite particles due to a groundwater flow will generate bentonite particles in a given groundwater condition, which can serve as a source of the colloids facilitating radionuclide migration through rock fractures.     

岩溶区土洞发育机制的分析

岩溶区地下水或地表水的活动 ,将对土层产生潜蚀作用及崩解作用 ,进而形成土洞。真空吸蚀作用 ,有利于土洞的发育扩大。地下水位的变化 ,将使土洞周围土体的应力状态发生改变 ,并有可能导致土洞周围土体产生塑性破坏 ,使土洞进一步扩大甚至塌陷.     

5 12汶川地震震后龙门山山前地表塌陷成因探讨

5 12汶川地震20余天后, 在四川省安县的安昌镇东南的李家院子村附近陆续出现了几十个地表塌陷坑并持续扩大。本文以李家院子地表塌陷坑群为研究对象, 根据其所在的地层、岩性、地下水、溶蚀作用和上覆土体的工程地质特性定性的探讨了该塌陷坑群的成因。初步认定钙质胶结砂砾基岩的存在是地表塌陷的先决条件; 强烈的地震动导致基岩岩体碎裂、解体、塌陷、并压密, 同时出现超孔隙水压力, 这使上层土体失去支持并开始启动塌陷; 余震的地震振动荷载作用导致地下土洞的形成和发展, 地下水的变化起到加速作用; 上覆土体的工程地质特性决定了塌陷坑在地表的浑圆形状。同时本文也注意到机械溶蚀和隐伏断层活动两种诱导因素的可能, 并简要阐述了相关背景依据。     

链子崖T_8－T_（12）缝段地下水的侵蚀性及其工程对策

在简述地形地貌、气象水文、构造部位和岩石组成等地质环境因素的基础上．本文重点研究了链子崖危岩体煤层采空区地下水的水化学类型及其对工程结构的侵蚀等级．并提出了地上排水、地下排水与采用抗侵蚀工程材料等综合的工程治理对策。     

广西喀斯特地区某工程人工挖孔桩施工问题与对策实践

广西喀斯特地区(以下称岩溶地区)岩溶发育、地下水丰富、水位埋藏浅的场地,人工挖孔桩施工中常遇到一些对施工不利的条件,本文通过工程实例,对岩溶地区类似工进行讨论,以期同行注意。     

一个地下水资源系统管理模型的研究

本文以三坝灌区地下水资源的开发利用为例,介绍了一个反映地下水运动规律的综合性数学模型,并且将数值法与地下水资源系统分析的线性规划方法结合起来,提供出一个完整的模型。目的在于对地下水资源系统进行优化管理。     

Mechanisms and Models for Bentonite Erosion Used for Geologic Disposal of High Level Radioactive Waste: A Review

The performance of the bentonite buffer in nuclear waste repository concept relies to a great extent on the buffer surrounding the canister having sufficient dry density. Loss of buffer material caused by erosion remains as the most significant process reducing the density of the buffer. In the worst case, the process is assumed to last as long as the free volume between the pellets in the pellets filled regions is filled with groundwater. Erosion rate and mass erosion are calculated based on the erosion model, and the measures are presented to prevent the geological disaster due to bentonite erosion. The groundwaters may solubilise the smectite particles in the bentonite and carry them away as colloidal particles. A dynamic model is developed for sodium gel expansion in fractures where the gel soaks up groundwater as it expands. The model is based on a force balance between and on smectite particles, which move in the water. Attractive van der Waals forces, repulsive electric diffuse layer (DDL) forces, gravity and buoyancy forces and forces caused by the gradient of chemical potential of the particles act to move the particle in the water. The effect of the fracture width and the frictions between particles and water and surrouding rock is analysed based on erosion model. The DDL forces strongly depend on the type of clay minerals and the type of ion and concentration in the water surrounding the particles. In the designed safe use of nuclear waste disposal (tens of thousands of years to hundreds of thousands of years), the safety of nuclear waste disposal is affected by the hydrodynamic and chemical effects, and bentonite erosion. Due to the bentonite erosion, the buffer/backfill layers become loose, and their permeability increases, which causes the nuclear element diffusion and convection, and even the nuclear disaster. In this paper, the mechanisms, models, experiments and control measures of bentonite erosion were systematically summarized. The current deficiencies of bentonite erosion were pointed out, and new methods were put forward to carry out the research for bentonite erosion. The measures were presented to prevent the geological disaster due to bentonite erosion through changes. The project is not only academic innovation, but also has a large practical significance. The research results of this project can be widely applied to the design, construction and maintenance of the bentonite buffer in nuclear waste repository.