共查询到20条相似文献，搜索用时 46 毫秒
1.
2.
Azizi Yacine Menani Med. Ridha Hemila Med Laid Boumezbeur Abderahmane 《Geotechnical and Geological Engineering》2014,32(2):363-374
This research work deals with the problem of karst sinkhole collapse occurring in the last few years in Cheria area (NE Algeria). This newly revealed phenomenon is of a major constrain in land use planning and urbanization, it has become necessary to locate and assess the stability of these underground features before any planning operation. Several exploration methods for the localization of underground cavities have been considered. Geological survey, discontinuity analysis, resistivity survey [ground penetrating radar has not been used as most of the Mio-Plio-Quaternary filling deposit covering Eocene limestone contains clay layers which limits the applicability of the method (Roth et al. in Eng Geol 65:225–232, 2002)] and borehole drilling were undertaken in order to locate underground cavities and assess their depth, geometry, dimensions, etc. Laboratory testing and field work were also undertaken in order to determine both intact rock and rock mass properties. All the rock mechanics testing and measurement were undertaken according to the ISRM recommendations. It has been found that under imposed loading, the stability of the karst cavities depends on the geo-mechanical parameters (RMR, Rock Mass Rating; GSI, Geological Strength Index; E, Young modulus) of the host rock as well as the depth and dimensions of the gallery. It increases with RMR, GSI, E and depth and decreases as the cavity becomes wider. Furthermore, the calculation results show that a ratio (roof thickness to gallery width) of 0.3 and more indicate, a stable conditions. The results obtained in this work allow identifying and assessing the stability of underground karst cavities. The methodology followed in this paper can be taken as a road map in the establishment of a hazard map related to the studied phenomenon. This map will be a useful tool for the future urban extension planning in Cheria area. 相似文献
3.
岩溶地区合理开发资源与防治地质灾害 总被引：6，自引：0，他引：6
卢耀如 《水文地质工程地质》2001,28(5):1-6
在地球上,自然灾害间存在着关系链,包括气候灾害与地质灾害间关系链,地质灾害与生物灾害间关系链,以及地质灾害间的关系链,不合理开发所有资源,都会诱发灾害,因此,讨论合理开发资源并防止诱发地质灾害问题,是非常重要的。 相似文献
4.
To minimize costs in conventional roadway design, as much low or valley areas as possible are utilized. In many areas of the eastern United States, these valleys are filled with carbonate rocks. Excavation is used to minimize grades—this removes protective overburden or rock cover over cavities; fill also is used to minimize grades—this can increase loads on marginally stable soil arches or rock cavity roofs. Surface water runoff is directed toward low areas—the low areas are likely zones of weakness or solutioning, thereby increasing the potential for sinkhole development and providing an opportunity for ground—water contamination, and remediation usually consists of blindly filling rock cavities, thus either channeling the still-contaminated surface flows someplace else or perhaps eliminating useful ground water recharge conduits. The authors suggest that the key to proper design, construction, and remediation for roadways planned in karst is to understand the geologic and hydrogeologic setting of the route(s) or locale, perform true geotechnical engineering design, and remediate with an understanding of the overall engineering geologic, hydrogeologic, and environmental picture. 相似文献
5.
对于围岩中存在管道型溶腔的岩溶隧道而言,受地表强降雨及地下水的影响,管道型溶腔内极易积聚高水压力,进而引发衬砌开裂、渗漏水及涌水病害。为了探明管道型溶腔中高水压力对衬砌结构的影响,开展了富水管道型岩溶隧道衬砌结构力学响应模型试验,对不同溶腔位置及不同水头高度影响下的衬砌结构内力特征进行了研究。基于此,建立扩展工况的数值计算模型,进一步探究了不同溶腔直径、溶腔位置及溶腔水头高度对衬砌结构内力的影响。结果表明：当隧道周围存在管道型溶腔时,与溶腔接触位置的衬砌内侧承受较大的正弯矩,为衬砌结构的最不利受力位置;随着溶腔直径和溶腔内水头高度的增加,衬砌内力显著增大;溶腔所在位置影响着衬砌内力的分布,当溶腔位于隧道拱顶时,衬砌结构的抗水压能力最小。研究结果可为管道型岩溶隧道的结构设计及安全施工提供借鉴。 相似文献
6.
针对小三峡隧道岩溶发育的工程地质特征,采用有限元方法建立典型隧道断面数值计算模型,分析充水溶洞位于隧道不同方位、不同距离时隧道围岩位移和塑性区变化规律,并结合围岩的位移变化情况和塑性区分布情况作为评价隧道围岩突水的判据,得出防止隧道围岩突水的岩层最小安全厚度。研究结果表明:在岩溶水压力作用下,当洞径比一定时,随着溶洞逐渐远离隧道,溶洞对隧道的影响在逐渐减弱;当间径比一定时,溶洞直径越大对隧道的影响越明显;同时根据围岩的位移和塑性区计算结果得到了隧道围岩最小防突厚度。研究成果可为小三峡隧道安全施工提供技术支撑。 相似文献
7.
岩爆是高地应力条件下地下洞室开挖过程中经常遇到的一种动力失稳的地质灾害,直接威胁施工人员和设备的安全。论述了岩爆的定义、特征及发生机理,应用国内外相关岩爆判据判定和理论分析,提出对马坑山隧道开挖过程中是否会产生岩爆做出了最终判定。 相似文献
8.
This paper is devoted to describe a new method of fuzzy logic applied to multi geohazards macro-zone maps. The basic steps are (1) compilation of macro-zone maps for each type of geohazard phenomenon. Each phenomenon is then assigned one of seven geohazard zones: very low, low, relatively low, moderate, relatively high, high, and very high; (2) definition of a membership function using a fuzzy logic algorithm to quantify the qualitative data, estimate a geohazard grade for each mesh point, and to convert qualitative maps to quantitative maps; (3) computation of the summed hazard grade for each mesh point and creation a cumulative geohazard map; and (4) compilation of a multi geohazards macro-zone map by defining a mathematical algorithm and again using fuzzy logic. The paper also describes a mechanism that takes subjective engineering judgments into account. Finally, a geohazard map with a scale of 1:25,000 (Rahdar district, Khuzestan, Iran) is compiled. This study divides the area into seven geohazard macro-zones. Zones of high and very high geohazard classification cover most of the area due to the large number of sinkholes and asymmetric subsidences, rock falls and other slop movements. Low and very low hazard zones only cover small localities. 相似文献
9.
This article discusses the various steps that the authors feel are necessary to the successful progression of an engineered
project sited in karst terrain. The procedures require a multidisciplined approach with liaison and cooperation among the
various parties to the project.
Initially, the prospective owner must have sufficient understanding of the potential engineering problems to incorporate the
engineering geologist into the early stages of any planned acquisition. The first step in an investigation should include
a review of the available geologic information, aerial photo interpretation, consultation with the State Geological Survey,
and a geologic reconnaissance of the prospective site and surrounding area.
A go-no-go decision as to purchase can often been made at an early time. Although, in some instances, more study is needed
for a particularly intriguing property.
The second stage should consider the various planning alternatives that are feasible based upon the limited available information.
At this stage planning/purchase decisions can be made as to purchasing options, value of the property, design constraints,
and the possible economic penalties that could be associated with the potential site construction. Various planning and construction
alternatives should be considered in this phase of the work.
The third stage should include a site investigation program of moderate size, consisting of test pits and/or exploratory borings.
The borings should be drilled using water as the drilling fluid, with an experienced crew and qualified technical inspection.
The authors find the use of geophysical techniques can be extremely misleading unless used in conjunction with exploratory
drilling. Successful evaluations using geophysical procedures occur only under ideal conditions.
The geotechnical viability of the plan and preliminary design should be investigated in the fourth phase. Additionally, the
physical parameters required for the design of structures founded atop cavities can be obtained at this time. Several support
schemes which incorporate cavity roof thickness, rock strength, and cavity space are discussed.
Possible construction procedures include excavation and dental concrete, grouting, piers or piles to sound rock, or moving
to another area. The relative economies of these procedures are discussed in relation to the size and depth of the soil or
rock cavity, possible future cavity formation, magnitude of loading and acceptable safety factors. 相似文献
10.
地质灾害危险性评价是防灾减灾工作的重要依据。本文以汶川县城周边64 km2为例,应用遥感信息提取技术与GIS空间分析方法,根据IKONOS遥感图像和地形图及野外调查资料,提取了崩塌和滑坡易发性评价因子,采用信息量法确定了因子分值,计算了崩塌和滑坡易发性,并分别提出崩塌和滑坡的危险性计算方法,形成了汶川地区崩塌和滑坡危险性分区图。研究结果表明:新的崩塌和滑坡危险性评价方法能够反映区内地质灾害危险程度,该方法可行,结果合理,这为中、大比例尺区域范围内地质灾害危险性研究提供了有益的思路。 相似文献
11.
The European part of Russia exhibits highly developed sulphate and carbonate karst. It mostly occurs within river valleys with relatively thin covering deposits. These conditions may induce karst collapses, which appear to be the main danger for civil and industrial buildings. Evolution of karst rocks includes several epochs of karst development, which causes complicated distribution of karst caves in karst rocks and, as the result, irregular distribution of karst caves on the surface. Karst hazards prediction is mostly reliable within the geotechnical system "Karst-Construction", using probability methods. This approach allows creating 3 types of antikarst protection (alternative design of construction arrangement on a plan, structural protection of a construction and plugging of karst caves beneath construction foundation) and selecting the optimum or the most effective version or their rational combination. 相似文献
12.
岩溶地区山体岩石裸露,地形坡度陡,其发育的危岩体一旦失稳,将对威胁区的居民生命财产造成严重危害,故及时准确地分析灾体的稳定及危害性极具意义。文中以贵州省松桃县和平社区长冲组危岩体为对象,结合工程勘查成果,分析了危岩体区的地形地貌、地质构造和水文特征等孕灾背景,并结合危岩体发育特征深入分析论证危岩体变形破坏模式及影响因素。在此基础上对危岩体稳定性进行定性及定量分析,评估了危岩体的危害程度及发展趋势。结果表明：发育于岩溶山区的危岩体,独特的喀斯特地貌、岩溶特征及复杂的结构面是控制其稳定性的关键因素,降雨、风化等作用为主要诱发因素。提出了初步防治方案建议,为后续采取治理措施提供参考依据。 相似文献
13.
朱国平 《中国地质灾害与防治学报》2005,16(B12):71-76
针对我国地质灾害发生量大面广的特点，介绍了岩土锚固技术在地灾防治工程施工中的应用技术措施，分析了地灾防治工程施工中遇到的特殊地质环境条件。在对复杂地层进行分析分类的基础上，分析了工程措施对造成地层复杂的影响因素，提出了克服复杂地层钻孔施工难度大应采取的施工工艺方法和技术措施，介绍了选择施工设备及机具的一般原则，对地灾防治工程施工具有一定的指导意义。 相似文献
14.
将TSP、地质雷达技术用于千岛湖配水工程灰岩区隧洞超前预报,简述了两种物探方法的原理,统计了完整性较好的灰岩与砂质岩对应的TSP指标范围,采用有限差分法模拟了地震波在隧洞前方遭遇大型溶洞时的波场特性,总结了岩性变化、溶洞、溶蚀带对应的物探异常规律。结论如下:地质雷达是溶洞、溶蚀带探测较理想的手段,其电磁异常特征表现为反射波振幅强,同相轴错断或呈双曲线状,并伴随一定程度的多次反射,含泥溶腔主频较空腔偏低,但多大于50MHz;同等质量级别下灰岩对应TSP各物理力学指标较粉砂岩或泥质砂岩偏好;大型空腔对应TSP纵波波速、密度及杨氏模量偏低,TSP对小型溶腔或溶蚀带探测敏感度较差,有时仅体现为反射层密集。 相似文献
15.
Preventing roof collapse in underground cavities is a challenge to geotechnical engineering. In this study, three independent methods have been used to evaluate the roof collapse of underground rectangular cavities for a range of geometries and rock properties. The rock mass strength has been described by the Hoek–Brown failure criterion. The results of the analysis allow for prediction of roof collapse and to determine whether the failure surface that develops in the rock mass remains localised or extends through the full depth of cover. This is of significance if there are overlying cavities and when estimating surface subsidence. 相似文献
16.
辽宁省大窑湾某建筑场地岩溶发育特征及工程地质条件评价 总被引：3，自引：3，他引：0
辽宁省大窑湾地区某建筑场地内基岩为可溶性中等~强的碳酸盐岩,岩体裂隙发育,在海水入侵、潜水与岩溶裂隙水等共同作用下,岩溶发育较强烈。本场地勘察揭露溶洞的见洞率70.27%。溶洞多发育于地表下20～3m之间,其次为30～40m。本文根据揭露溶洞的大小将溶洞分成大型溶洞（洞高≥4m）、中偏大型溶洞（2m≤洞高＜4m）、中型溶洞（0.5m≤洞高＜2m）和小型溶洞（洞高＜0.5m）等四类,分析表明本场地内溶洞以中型溶洞为主,其次为小型溶洞和中偏大型溶洞,岩溶的发育和分布对场地工程地质条件影响较大。本文围绕场地岩溶发育这一主要工程地质问题,从岩溶发育的地质背景、形成条件、分布特点等方面对场地内的岩溶发育特征进行了分析研究,认为本场地属于岩溶中等～强发育的复杂的岩溶红粘土地基,需采取CFG桩、振冲碎石桩复合地基或采用桩基等措施对地基进行处理,以保证工程安全。 相似文献
17.
重大城市线性工程施工可能会诱发或面临一系列的地质灾害,对其灾害特征、危害及防治方法进行研究具有重要意义.以南水北调工程北京段PCCP管道施工为例,在分析其地质环境背景、地质灾害类型、基本特征、危害性及影响范围的基础上.归纳总结了针对不同类型地质灾害所采用的施工防治措施和方法.重点对施工沿线主要地质灾害如边坡崩塌、特殊地基处理和地面沉降做了深入的探讨.研究成果对PCCP管道后续工程建设和工程运营维护具有一定的现实意义.是对线性工程地质灾害防治进行的有益的探索. 相似文献
18.
板块缝合带作为特殊类型的“断层”,其地质灾害效应是工程地质与灾害地质研究的重要内容,对工程建设具有重大现实意义.受特提斯洋复杂而漫长的构造演化制约,川藏交通廊道穿越了7条板块缝合带,但对其地质灾害效应的研究却鲜有涉及.为此,在搜集整理已有研究成果的基础上,结合野外地质调查和室内研究,简要分析了川藏交通廊道沿线板块缝合带的地质灾害效应,并探讨其内在机理.结果表明：板块缝合带地质灾害效应主要表现在塑造地貌、创造地形条件,劣化岩体、提供物质来源,控制地质灾害的分布和诱发地质灾害（链）等4方面.构造混杂岩因其复杂的地质演化过程和特殊的岩石类型与组合特征,使其天然具有易灾性,而板块缝合带就位过程中的构造运动是地质灾害效应的内生动力.板块缝合带的地质灾害效是贯穿于川藏交通廊道沿线板块缝合带构造演化过程中的内、外动力地质作用耦合的外在表现形式.板块缝合带地质灾害效应研究目前处于起步阶段,建议在加强基础地质与灾害地质精细化调查的基础上深化其认识;川藏交通建设工程应加强板块缝合带工程效应研究,加大地质灾害监测预警系统研发,以确保其安全施工与后期平稳运行. 相似文献
19.
地下盐穴储气库安全性是蓄气运行的关键地质问题.针对平顶山盐田盐层薄、夹层多以及埋藏深等特征,从薄层状盐岩的渗透性、流变性以及稳定性3个方面,详细讨论了储气库的地质可储性及地面沉降问题.首先采集了纯盐岩、互层状盐岩、泥岩夹层3种岩石试样,分别进行了电镜扫描和不同应力水平下的三轴压缩蠕变试验,并应用CYT法对试验区进行了深部盐岩溶腔的探测.鉴于试验区多个采井影响区的重叠,地面沉降量实际监测结果比较复杂,绝对值偏小但具有波动性.综合上述地质特征,作出了平顶山地下盐穴储气库地质条件良好的结论,为我国同类工程提供一定的实际参考. 相似文献
20.
三峡库区移民迁建中发现的岩溶问题是一个重大工程地质问题。巫山县新城二郎庙小区是地质灾害监测预警示范区,那里的三叠系嘉陵江组灰岩在特殊的气候、水文和地质环境下遭受了强烈的岩溶作用,岩体结构变得非常复杂,完整的灰岩变为层状碎裂岩体、岩溶角砾岩、泥质条带和残坡积角砾层。不同的地貌部位具有不同的岩溶特点和强度,总体规律性是由西向东、剖面下部至上部岩溶作用增强,其中陡坡下地形由陡变缓的转折地带和冲沟下部是岩溶作用最强烈的地带。岩溶作用形成了各种微地貌和特殊的岩体组合格局。岩溶导致岩体的力学强度和稳定性不断降低,加上其他自然因素和人为因素作用可能产生地面不均匀沉降、地裂缝、滑坡、崩塌、泥石流和地面塌陷地质灾害,这些问题必须在移民迁建以及将来城镇运行过程中引起高度重视。 相似文献