小型溶洞对隧道稳定性的影响分析   总被引：1，自引：0，他引：1  

邵勇  阎长虹  许宝田  王宁  郑军 《地质论评》2012,58(3):519-525

根据钻探、物探资料,拟建南京地铁3号线滨江路站—五塘村站沿线穿越的灰岩地层中有数量较大的洞径为2～3m的小型溶洞。通过对该地区地质背景的分析发现,岩溶明显受断裂构造控制,溶洞发育规模小但数量多,对开挖后隧道的围岩稳定性有一定的影响。采用数值分析法研究了小型溶洞尺寸、与隧道位置关系等不同因素对隧道围岩稳定性的影响。计算结果表明,当溶洞尺寸和位置变化时,围岩塑性区也发生变化,塑性区面积随着溶洞尺寸的增大而增大。溶洞位于拱肩时塑性区面积最大,对围岩的稳定性影响大,位于拱腰时最小。隧道开挖后拱顶和拱底处最易破坏,相近条件下串珠状溶洞比单个溶洞的危害性要大。  相似文献   

福建连城赖源溶洞化学沉积类型及成因     

梁诗经  文斐成  兰莎  毛凌云  魏勇 《福建地质》2012,31(4):336-350

赖源山间盆地西南缘上村一带出露二叠系船山组、棲霞组石灰岩,发育幽琴洞、仙云洞等溶洞组成的溶洞群,溶洞内岩溶发育系统完整,重力水沉积、非重力水沉积、混合水流协同沉积、叠置沉积的化学沉积物类型齐全。其数量繁多的莲盆笋、莲盆柱、卷曲状石枝,规模庞大的细纹边石坝为福建其他溶洞所罕见。赖源溶洞保存完好、景观优美的钟乳石是研究洞穴不同环境及流态水流化学沉积的良好地质遗迹,也是溶洞旅游的宝贵资源。  相似文献   

Stable Carbon Isotope Variations in Cave Percolation Waters and their Implications in Four Caves of Guizhou, China     

LUO Weijun  WANG Shijie  XIE Xingneng  ZHOU Yunchao  LI Tingyu 《《地质学报》英文版》2013,87(5):1396-1411

Monitoring and sampling of main plants,soil CO2,soil water,bedrock,spring water,drip water and its corresponding speleothem were performed at four cave systems of Guizhou,Southwest China,from April 2003 to May 2004,in order to understand stable carbon isotope ratios variations of dissolved inorganic Carbon(DIC) in cave percolation waters(δ13CDIC) and their implications for paleoclimate.Stable carbon isotopic compositions and ions(Ca,Mg,Sr,SO4,Cl etc.) were measured for all samples.The results indicate that there are significant differences among the δ13CDIC values from inter-cave,even inter-drip of intra-cave in the four caves.The δ13CDIC values from the Liangfeng Cave(LFC) is lightest among the four caves,where vegetation type overlying the cave is primary forest dominated by tall trees with lighter average δ13C value(–29.9‰).And there are remarkable differences in δ13CDIC values of different drip waters in the Qixing Cave(QXC) and Jiangjun Cave(JJC),up to 6.9‰ and 7.8‰,respectively.Further analyses show that the δ13CDIC values in cave drip waters are not only controlled by vegetation biomass overlying the cave,but also hydro-geochemical processes.Therefore,accurate interpreting of δ13C recorded in speleothems cannot be guaranteed if these effects of the above mentioned factors are not taken into consideration.  相似文献   

Seismotectonic versus man-induced morphological changes in a cave on the Arrábida chain (Portugal)     

José António Crispim 《Geodinamica Acta》2013,26(3-4):135-142

Abstract

Distinctions between cave morphologies originating from seismic or active tectonics and those generated by natural clastic breakdown or by human activity must be made using unambiguous interpretative criteria.

Easily accessible caves in particular, which may have been visited for centuries or millennia, or caves located near engineering works or quarries using great quantities of explosives, may have broken speleothems, breakdowns or detachment joints unrelated to seismic events or tectonic movements.

Zambujal cave lies near neotectonic and seismic structures associated with a Plio-Quatemary 200 m uplift of the Arrábida chain and has suffered impacts resulting from quarrying, followed by possible vandalism. It is thus an example for which it is difficult to decipher morphological agents as there is the possibility that identical forms have been generated by several causes, which may have repeated at different episodes of its evolution. However, a careful morphological interpretation makes it possible to accept the existence of two seismic episodes, an “ancient” one and a “modern” one. The detection of other episodes between these is only possible using absolute dating. © Elsevier, Paris  相似文献   

Tectonics of the Western Carpathians in the light of recent studies     

《Geodinamica Acta》2013,26(1-3):1-2

During an annual cycle the affect of microclimatic changes (of natural and anthropogenic origin) on the geochemical characteristics of seepage water and mineral precipitation rates was analyzed for two karstic caves which contrast in environmental stability and energy exchange with exterior. On the one hand, Castañar cave (Caceres, Spain) is an extremely controlled show cave with limited visitation showing a minimum exchange rate of energy with the external atmosphere and, secondly, Canelobre cave (Alicante, Spain), is a widely visited cave where the anthropogenic impact generates rapid and high-energy environmental changes. Mineral saturation state of seepage water of both caves is controlled by microclimatic variations, such as: 1) natural underground air renewal through the porous system of the upper soil and the network of host-rock fissures, or elso through the cave entrance, 2) cumulative disruptions in the pCO2 levels of cave air due to the presence of visitors, and 3) forced ventilation of the subterranean atmosphere due to the uncontrolled opening of cave entrances. The obtained results reinforce the significance of the microclimatic fluctuations on short time scales in the dynamics of the subterranean karst systems, in terms of rates of mineral precipitation and growth of speleothems, as well as their key role for cave conservation.  相似文献   

岩溶石山区山坡表层径流水文动态特征对比分析——以桂林丫吉试验场为例   总被引：3，自引：2，他引：1       下载免费PDF全文

陈国富  姜光辉  周文亮  王开然 《水文》2013,33(5):58-63

选择桂林丫吉试验场溶洞—硝岩洞及其上方的汇水坡面作为研究区,通过在不同降雨条件下,对坡面径流和硝盐洞中流水水文动态进行监测并做对比分析研究。结果表明:（1）降雨强度、降雨持续时间和各含水系统前期含水情况决定了岩溶石山区坡面地表和包气带水文动态变化过程;（2）在不同降雨条件下,地表坡面流和经过上部包气带调蓄过的硝盐洞水文动态都表现为暴涨暴落,坡面径流表现的更为明显,一般坡面径流的整个水文过程持续几个小时到十几个小时,而硝盐洞中流水水文过程持续13d;（3）一般大到暴雨条件下,坡面流最大流量大于硝盐洞,但由于持续时间短,其一场降雨后所获得的水量远不如下渗到包气带—硝盐洞中滴水水量。  相似文献   

旅游活动对洞穴环境的影响及洞穴的自净能力研究——以重庆雪玉洞为例   总被引：7，自引：1，他引：6  

徐尚全  殷建军  杨平恒  周小萍  沈立成 《热带地理》2012,32(3):286-292

洞穴空气中的CO2对洞穴次生化学沉积物的沉积和溶蚀有重要的影响.文中基于2010-09-30- 10-08对重庆雪玉洞洞穴CO2浓度、温湿度进行的为期8d的连续监测,并结合“十一”黄金周期间的客流量进行综合分析.结果发现:(1)受旅游活动的影响,洞穴内空气CO2浓度有明显的累积效应;温度变化幅度加大,但没有累积效应;由于地下河和滴水的影响,洞内空气相对湿度一直处于过饱和状态,这是温度没有形成累积效应的一个重要原因.(2)由于洞内外温差的影响,洞口处会形成由洞内向洞外流动的气流,使得近洞口处的空气CO2浓度  相似文献   

岩溶表层带水生动物研究进展   总被引：2，自引：1，他引：1  

刘伟  周翠英  袁爱华  BRANCELJ Anton 《中国岩溶》2016,35(6):712-719

本文旨在介绍岩溶表层带水生生态研究中微小甲壳类生物的最新研究进展,相关研究国内还少有涉及。岩溶表层带不仅仅是岩溶地下含水层的一个重要组成,而且是岩溶发育的活跃地带,同时也是大量地下生物生存的栖息地。目前,岩溶表层带内甲壳类主要采自洞穴滴水,残留的滴水水洼以及裂隙中的水体。这些甲壳类主要是桡足类,也有其他甲壳类,如端足目和介形虫,它们主要为暗层生物（stygobiont）,也包括一些陆生物种。以斯洛文尼亚为例,在所调查的洞穴中平均每个洞穴有近9个暗层桡足类物种,为了适应表层带特殊的地质环境,这些物种在形体上存在适当的进化。表层带的众多地质因子如顶板厚度、栖息地的连通性、及栖息地的大小等,以及水文因子包括水文动态特征、水化学特征等,都对这些物种的组成与分布有较大的影响。虽然岩溶表层带及其水生动物的独特性和重要性已逐步得到了许多地质学家和生物学家的认可,但还有很多问题有待进一步的解答,譬如邻近群落间差异性,以及桡足类对非饱和带水流指示作用等。   相似文献   

充水溶洞特征的高密度电阻率法反演分析研究   总被引：3，自引：3，他引：0  

周文龙  吴荣新  肖玉林 《中国岩溶》2016,35(6):699-705

在高密度电法勘探中,不同性质的溶洞其反演电阻率特征有差异,溶洞为空洞时反演电阻率表现为高阻,充满水时表现则为低阻,而充水溶洞的电阻率反演特征很难判断。文章通过构建不同充水程度的溶洞模型进行正演模拟,利用最小二乘法对模型的地电断面进行反演,对比不同反演成像模型的地电响应特征。结果表明,充水溶洞的电阻率随溶洞充水量的增加而减小,低阻的范围随着水量的增加而不断扩大,其可分辨性强。野外探查资料进一步验证了模拟结果,所获得的认识对地下溶洞的电法探测分析具有一定的指导意义。   相似文献   

塔里木盆地北缘奥陶系古溶洞和古岩溶沉积中包壳砾石和包壳砾岩的发现及特征^*          下载免费PDF全文

钟建华  倪良田  曹梦春  陈鑫  张丹锋  孙宁亮  郝兵  刘闯  邵珠福  牛永斌 《古地理学报》2016,18(5):721-730

塔里木盆地北缘奥陶系发育典型的古岩溶,笔者在其中发现了一种非常特殊的沉积物或沉积构造:包壳砾石和包壳砾岩,且这种包壳砾岩之前从未见报道。该包壳砾石和包壳砾岩的结构类似鲕粒或核形石,可分为核心和包壳2部分,大部分呈近圆形或扁圆形,少数形态不规则,直径为数厘米到数十厘米。核心可分为4种,分别是:(1)与溶洞围岩相同的灰岩砾石;(2)由砂岩形成的核心;(3)由砾岩构成的复合核心;(4)由古钙华碎块形成的核心。包壳也可分为4种类型,分别是:(1)具有圈层的包壳;(2)颗粒状包壳;(3)均质包壳;(4)由颗粒状包壳和圈层状包壳组合形成的复合包壳。包壳砾石和包壳砾岩是溶洞和岩溶沉积中的典型产物,其不仅可以作为识别溶洞和岩溶的标志之一,而且具有一定的储集能力,是一种有效的油气储集体。  相似文献