某大厦地下室施工排水和结构防水技术措施

1　工程概况江门市某大厦地面上二十三层 ,地下室一层 ,内设停车场、消防水池、电梯井、配电房等。地下室面积2 90 0ｍ2 ,基坑深 5 6ｍ。场地土层为 :①耕植土 ,厚 0 8～ 1 0ｍ ;②粘性土 ,厚 1 0～ 2 5ｍ ;③淤泥 ,厚 2 3～ 3ｍ ;④粘土 ,厚 1 5～ 2 0ｍ。场地地势较低 ,地下水为潜水 ,水源补充条件良好 ,水位在地面以下 1 0ｍ处变化。2　基坑施工排水技术措施基坑原设计采用粉喷水泥土桩支护开挖 ,后从经济角度考虑 ,改为二级放坡、明排水法开挖 (图 1)。施工过程中采取了以下排水技术措施 :图 1　基坑开挖方案示意图Ｆｉｇ .1　Ｔｈ…     

岩溶深基坑的环境工程地质问题及其防治措施

岩溶地区深基坑开挖常诱发较多的环境工程地质问题。基坑排水形成地下水降落漏斗,诱发岩溶地面塌陷;开挖导致基坑壁滑塌;造成周围建(构)筑物破坏或局部拉裂。本文分析了工程地质条件、水文地质条件、基坑支护体和周边建筑等对深基坑开挖的影响。提出了深基坑开挖中应注意的问题以及防治措施。     

内撑式支护的软土基坑开挖抗隆起稳定性分析

采用强度折减法有限元方法（SSRFEM）,分析了不排水条件下软土地基中内撑式排桩支护基坑开挖的抗隆起稳定性,并研究了软土不排水抗剪强度、支护结构条件、基坑尺寸对基底抗隆起的影响。研究表明,以往通常采用的极限平衡公式,对基坑开挖基底抗隆起稳定分析不能完全考虑支护结构的影响,也不能考虑基坑侧壁位移的影响,在一些条件下误差较大,而SSRFEM分析方法是求解基坑极限状态实际而自然的破坏形式,可很好地分析基底隆起稳定性。     

基坑边缘超近距建筑物变形分析与控制

安外小关东街住宅楼工程的基坑开挖线局部与既有6层宾馆扩大基础外缘重合，为确保宾馆的安全，在设计过程中，采用了3种应用较普遍的基坑支护设计软件进行分析比较，并在施工过程中采用了复合支护措施，保证了基坑顺利开挖和宾馆的安全。从基坑周围建筑物沉降观测结果来看，该基坑支护的设计及施工是成功的。     

漳州中银大厦基坑突涌处理方法

漳州中银大厦基坑开挖时发现基坑底部压密注浆隔水失败，导致下部承压水顶穿薄层粘土及底部注浆层，从而产生基坑突涌。简要介绍了利用管井降水降低基坑下部承压水的主要方法和过程。     

某超大型深基坑逆作法施工

绍了一大型深基坑工程采用逆作法设计、施工情况。3层地下室深基坑围护结构采用地下连续墙，采用负一层结构作为支撑体系，一直开挖至基坑底，土方开挖采用半逆作放坡开挖、盆式开挖及两层盖挖等多种方式，提高了出土效率，中间支承柱采用钢管柱和钢筋混凝土柱，裙楼部分支承柱采用钢筋混凝土预制柱，降低了工程造价。     

运达国际广场深基坑支护工程流砂层治理方法

介绍了长沙运达国际广场深基坑支护工程流砂层治理方法，分别论述了人工挖孔桩、锚杆施工、基坑坑壁加固、基坑开挖等工艺在流砂层施工过程中所遇到的重重困难和采取的各种措施，为深基坑支护工程施工提供了借鉴经验。     

江西人民出版社综合楼基坑支护设计与施工

在江西人民出版社综合楼基坑支护中，采用放坡开挖结合水泥土墙的联合支护方式，在深厚填土层及流塑状淤泥地层，用经济的方法成功地进行了基坑支护施工。     

某水力枢纽基坑开挖过程渗流耦合数值模拟

岩土工程中存在多种耦合作用,在水利水电工程中,渗流场与应力场的耦合是最重要的。以某水利枢纽厂房基坑开挖为工程背景,比奥固结理论为理论基础,莫尔-库仑准则为土体屈服判据,对基坑开挖过程中渗流耦合进行了数值模拟。计算结果显示：回填后的应力略大于开挖过程中的应力,沉井附近出现一定程度的应力集中。回填前后塑性区变化不大且范围较小,因而土体的屈服破坏不是该工程的重点。由于土体渗透系数大,厂房区地下水位高,基坑开挖过程中渗水量较大,回填后沉井及基坑底部防渗底板的防渗效果显著,因而在基坑开挖过程中防渗排水是该工程的重点问题。     

润扬桥基三维裂隙网络渗流数值模拟

润扬长江大桥北锚碇是大桥关键工程，承担大桥悬索较大拉力。北锚碇的基础为花岗岩裂隙岩体，分布断裂和多组裂隙，星岩表部风化，上覆约45m厚的第四系松散沉积层，基坑开挖深度达48m，基坑内外水头差达47m。如何做好防渗和排水，对施工期的安全和施工质量至关重要。为此，采用离散裂隙网络渗流的三结构模型与连续介质渗流模型相结合，对北锚碇场区的地下水渗流进行了多种工况的数值模拟，为基坑防渗和排水设计提供了主要参考依据，其数值模拟结果已得到后来施工期实际资料的验证。     

淮河流域(河南段)第四系含水层特征

本文确定了第四系含水层划分原则,根据该原则将工作区划分为第一、第二及第三含水层,阐述了各含水层岩性、水文地质参数、富水性及地下水循环特征,建立了地下水循环流动框图.     

煤炭开采条件下三姑泉域岩溶含水层保护评价

三姑泉域是我国典型的北方岩溶区,同时位于国家规划的晋东大型煤炭基地,煤炭开采与水资源保护之间的问题较为突出。多年来区内煤炭资源的大规模开采造成了区域地下水位下降、水质恶化等现象。因此开展北方岩溶区煤炭基地含水层保护评价对水资源保护及经济可持续发展具有十分重要的意义。本文从含水层脆弱性、含水层功能和煤炭开采影响力三方面建立综合评价指标体系,采用APH法进行三姑泉域岩溶含水层综合保护评价。针对煤炭基地特征,采用增加了煤炭采空区指标的COP修正模型评价了含水层的脆弱性。含水层功能评价分别从供水能力与生态、大泉维持能力开展;煤炭开采影响力评价从开采活动及煤炭地质结构两方面开展。综合评价结果显示需要重点保护的区段为岩溶大泉、水源地及地表渗漏段,其次为岩溶强径流带及煤炭剧烈开采区,与实际情况相符。      

地热井洗井及增产工艺技术探讨

本文从地热井钻探过程入手,分析了钻井过程中对含水层通道的污染因素,系统总结了地热井的洗井工艺和流程、水层改造增产技术及变更设计增产技术,在地热钻井中的应用。     

Behaviour of chromium VI in a multilayer aquifer in the industrial zone of Annaba,Algeria

Industrial wastewater is characterised by the presence of a great quantity of metallic micro-pollutants, among which chromium by its mobility, contaminates the surface and groundwater. The study of different aquifers within the area of Annaba (Algeria) shows extremely variable chromium concentrations in the unconfined aquifer (0–0.22 mg l⁻¹), which becomes practically null in dry period; on the other hand, they remain relatively constant in the deep confined aquifer (about 0.04 mg l⁻¹). To specify the mechanisms of chromium migration in the aquifer system, a study of space–time evolution of chromium concentrations in unconfined aquifer was undertaken, while considering the kinetics of diffusion in the deeper aquifer. Chromium, indirectly reduced microbiologically by sulphate-reducer bacteria in the upper aquifer, is likely to anticipate the auto-depuration capacity of the ground and to reduce the quality of groundwater.     

屋面雨水回灌裂隙岩溶水水岩作用实验研究

在济南大学西校中采集奥陶系灰岩岩样,并设置不同的地下水、雨水混合比例进行室内溶蚀模拟实验。通过pH、电导率及几种常规离子的测定,并利用水文地球化学模拟软件PHREEQC等方法,分析雨水回灌含水层后与原有的地下水以及含水层介质之间的水—岩相互作用。结果表明:(1)地下水、雨水混合后,随振荡的持续进行,以及温度升高和脱碳酸作用的影响,水中CO2分压不断下降;(2)Ca2+浓度在混合比例为9∶1、7∶3和5∶5时略有下降,其它离子浓度无明显变化;(3)随雨水和岩溶系统作用时间的增加,方解石、白云石和石膏的饱和指数均不断减小,且随着雨水回灌量的增加,方解石、白云石饱和指数减小明显,从混合比例9∶1时的0.23~-0.39和0.05~-0.97到1∶9时的-0.34~-0.62和-1.59~-2.57,表明雨水能增强对方解石、白云石乃至整个含水层的溶蚀,且雨水回灌量越大,溶蚀作用越强烈,影响越明显;(4)雨水回灌所形成的溶蚀量比较有限,不会对回灌井周围含水层稳定产生严重影响。      

鄂尔多斯盆地白垩系含水砂岩的特征

最新水文钻孔和露头剖面调查测试资料对鄂尔多斯盆地白垩系含水砂岩的组分特征和空间分布综合研究表明,宜君-洛河含水岩组广泛分布于全盆地,为最主要的区域性含水岩组,以长石石英砂岩、长石砂岩、岩屑长石砂岩发育为主;华池-环河含水岩组分布广泛,也是很好的含水岩组,主要为长石砂岩、长石石英砂岩、岩屑长石砂岩：罗汉洞-泾川含水岩组仅局限于盆地北部和西部,是一套比较局部的含水层,主要为长石石英砂岩和岩屑石英砂岩。总体上,盆地北部白垩系含水砂岩极其发育,南部含水砂岩具多层分布的特点,厚度总体较小。     

海潮引起有越流的滨海承压含水层地下水头变化的数值模拟

海潮波动可以引起海岸带有越流的承压含水层地下水头发生波动。建立了基于有限差分法的滨海地区一维承压含水层地下水运动数值模型。通过将潮汐波动概化为正弦波,分别对初始水头水平及线性倾斜的承压含水层模拟了滨海地区有越流的承压含水层地下水头随潮汐波动的变化。通过对两种情形下的变化比较,结果表明,受海潮影响的滨海承压含水层地下水头与海潮有相似的波动特征,但变幅减小,受海潮的影响程度与离海岸的距离有关,随着离海岸距离的增加,地下水头的变幅及潮汐效率呈负指数函数衰减,水头倾斜情形下变幅更小,潮汐效率更小,滞后时间更短,地下水头对海潮的滞后时间随距离呈线性增加。     

刘桥矿区地下水环境同位素特征研究

通过对刘桥矿区主要含水层的环境同位素测试分析,表明研究区内各含水层δ18O值为-5.5 1‰~-10.87‰,平均-9.34‰;δD值为-5 6.3‰~83.4‰,平均-71.4 8‰,且δD与δ18O值自浅到深依次降低。还分析了该矿区地表水、新生界松散层一含水和二含水、煤系砂岩水、太灰水、奥灰水氢氧稳定同位素一般特征,研究了矿区主要含水层水的补给环境及奥灰水与其他含水层之间的联系。      

Interpreting the borehole water chemistry of the Permo-Triassic sandstone aquifer of the Liverpool area,UK

Using hydrogeological data, historical chemical data and the results of studies in adjacent aquifers, an interpretation of the water chemistry from a sparse network of boreholes is presented for the Liverpool area. The chemistry of the fresh groundwater samples is influenced by geology, pollution and pumping history. The oldest waters, present where the sandstone is covered by Quaternary deposits, are calcite-saturated, contain little NO⁻₃ and have low SO²⁻₄ and Cl⁻ concentrations. However, water from the Collyhurst Sandstone are depleted in HCO⁻₃ whatever the concentrations of the other anions. Samples from boreholes in areas where the sandstones are not covered by Quaternary deposits are characterized by very low alkalinity and pH, and by high NO⁻₃, SO²⁻₄, and Cl⁻. In the regions of the aquifer close to sandstone outcrop, or where the Quaternary deposits are thin, the water samples have higher alkalinity and pH, and lower anion concentrations. Scattered throughout the region are boreholes yielding waters with very high SO²⁻₄ concentrations: where associated with industrial sites, these waters also have high NO⁻₃ concentrations and industrial pollution is suspected. In rural areas the high SO²⁻₄ concentrations are derived from leakage through the sulphur-bearing tills in response to pumping-induced lowering of the piezometric surface. The distribution of borehole water types can be described with the help of a set of rules relating water type to hydrogeological features; these rules allow a map of hydrochemical distributions to be constructed. Saline groundwaters occur in the aquifer adjacent to the Mersey Estuary and have chemistry compositions equivalent to slightly modified, diluted Estuary water. With the exception of a single deep borehole sample, there is no indication of the widespread presence of ancient saline groundwaters in the base of the sandstone sequences as is found in the sandstones to the east of the study area. However, slightly saline, reduced waters occur below the Mercia Mudstone Group in the north of the area. Historical records give some indication of the changes in water chemistry distributions through time.     

Hydrogeochemical characteristics of groundwater from the two main aquifers in the Red River Delta,Vietnam

In the Red River Delta, situated in the northern part of Vietnam, nearly its entire population depends solely on groundwater for daily water consumptions. For this reason, groundwater quality assessments must be carefully carried out using hydrogeochemical properties, to ensure effective groundwater resource planning for the Delta’s present and future groundwater use. In this study, the spatial and seasonal changes in the hydrogeochemical characteristics of groundwater in the two main aquifers of the RRD were investigated by analyzing the physicochemical data obtained in 2011 from 31 conjunctive wells in the Delta’s Holocene unconfined aquifer (HUA) and Pleistocene confined aquifer (PCA) using the Piper diagram and the Gibbs diagram. Results of the data analysis show that the groundwater in both aquifers in the upstream area of the delta is dominated by the [Ca²⁺–HCO₃⁻] water-type, while the [Na⁺–Cl⁻] dominates along the middle-stream and downstream areas. Seasonal changes in the hydrogeochemical facies in both aquifers, comparing the results for the dry and the rainy seasons, were detected in about one third of the sampling wells, which were mainly located at the upstream portion of the Delta. The hydrogeochemical facies of HUA were different from that of PCA by about 45% of the sampling wells in both the dry and the rainy seasons, which were found mostly in the upstream and middle-stream areas.