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1.
广州市白云区夏茅村岩溶塌陷地质灾害严重,塌陷区内地质环境条件极其复杂,隐伏灰岩岩溶土洞发育强烈,溶洞、土洞规模较大,且发育多层溶洞,溶洞间相互连通,岩溶塌陷区基岩面起伏较大,高程变化剧烈,第四系覆盖层厚度较大,底部粉质黏土层土洞发育,土体中规模巨大的土洞是产生岩溶地面塌陷的基础条件。基岩断裂构造带及其影响带范围内,岩石破碎,形成导水断层,存在地下水迳流通道,沿断裂带地下水循环活跃,溶蚀强烈,形成岩溶强发育带,为岩溶塌陷的发生提供了良好的动力条件。区内楼房基础施工扰动了地下水和土洞间的平衡状态从而成为了地面塌陷发生的诱发因素。运用7项地质环境条件指标和5项经济人口指标分别定性评估岩溶地面塌陷的易发度和易损度,并将二者叠加进行地质灾害风险评估。研究结果表明,夏茅村潜在地质灾害风险大,只有严格控制地下水动力条件,才能避免再次发生岩溶地面塌陷。 相似文献
2.
研究区内已发岩溶地面塌陷灾害严重,地质环境条件极其复杂,第四系覆盖土层厚度大,底部粉质黏土层土洞发育、隐伏基岩为壶天群灰岩,溶洞及断层破碎带发育,单个溶洞、土洞规模较大,溶洞与溶洞、土洞与溶洞之间连通性能较好。岩溶地面塌陷是以覆盖层粉质黏土层或砂类土层的扰动和土洞的形成为起点的,根据勘查区上覆盖层二元结构的特征,区内地面塌陷及土洞的发育过程可分为"下黏上砂"二元结构塌陷模式和"下黏上砂、软土"多元结构塌陷模式,塌陷区的岩溶塌陷致塌机制主要为机械贯穿作用,塌陷发育大约经历了四个阶段,建议今后不宜在勘查区及其周边一定范围进行地下工程建设活动及抽、排岩溶地下水行为,避免地下水动力条件发生改变,再次发生岩溶地面塌陷。 相似文献
3.
武汉地区浅层岩溶发育特征与岩溶塌陷灾害防治 总被引：6，自引：5，他引：1
运用综合分析和数学统计的方法,较为深入地研究了武汉地区浅层岩溶的发育特征。武汉地区存在6个走向 NWW-SEE、各自相对独立的碳酸盐岩条带。根据上覆盖层工程地质性能的差异,划分出5种岩溶地质结构类型。武汉地区浅层岩溶主要类型有溶隙、落水洞及小型溶洞等,钻孔遇洞率46.0%-50.1%,线岩溶率5.93%-6.00%。浅层岩溶带中,1/3的溶洞洞高小于0.6 m,50%小于1.0 m,90%小于3.0 m。1/3的溶洞顶板在基岩面以下2.5 m 以内,50%在4.5 m 以内,90%在12.5 m 以内。溶洞充填物主要是黏土,含有灰岩碎块石。全充填溶洞占70.8%,未充填溶洞约占1/5,半充填溶洞不到8%。全充填溶洞顶板在基岩面以下平均埋深5.13 m,半充填5.71 m,无充填7.69 m,且具有全充填和半充填溶洞埋深较小、无充填溶洞埋深较大的特点,反映出溶洞充填方式是自上而下充填,充填物主要来源于上部覆盖层。武汉地区浅层岩溶为上部“垂直渗流岩溶带”地下水垂直渗流作用下的产物。根据岩溶发育程度的差异,基岩面以下浅部碳酸盐岩在垂直方向上可分为上部强岩溶和下部弱岩溶两个带;岩溶塌陷灾害平面上可划分出高、中、低3个危险性区,各区防治原则不同。高危险区是岩溶塌陷灾害防治的重点,防治的基本原则是阻止上覆粉细砂的流失;中等危险区的防治原则是保护中部老黏土层或红层的完整性;低危险区应注意远城区土洞存在的可能性。各危险区治理应以岩溶地质结构为基础,在防治原则指导下制定相应的防治措施。此外,工程建设中应合理选择和利用弱岩溶带。 相似文献
4.
地面岩溶塌陷的高分辨地震勘查 总被引：4，自引：0，他引：4
地面岩溶塌陷是地质灾害主要灾种,由于其突发性,对人类的生产和生活造成威胁。浅层高分辨地震技术可以查明形成塌陷的基岩地质条件,特别是横波反射法可以查明覆盖层中地下水作用形成的潜蚀带或土洞等覆盖层地质条件。勘查洞穴是岩溶塌陷地震勘查方法面临的特殊问题,为了解土洞、溶洞形成的地震反射信号特征,专门进行二维固体超声波模型试验。唐山市岩溶塌陷勘查实例表明,高分辨地震技术可探明基岩埋深、断层、破碎带及覆盖层潜蚀扰动区,为防冶工程设计提供地质背景资料。 相似文献
5.
岩溶土洞稳定临界深度的初步研究 总被引：1，自引：1，他引：0
在岩溶土洞发育地区进行工程建设时需要确定土洞是否会发展成地面塌陷和对工程结构物稳定性有影响,分析表明土洞临界深度可作为评价土洞稳定和加固深度的依据。本文采用有限元分析方法,以土洞塑性区贯通至地面或路基表面作为土洞发展成地面塌陷和临界深度的标准。研究表明,土洞的临界深度与土洞形状、土洞尺寸、位置和路基填土厚度有关;土洞断面形状为圆形时临界深度最小,土洞尺寸越大,路基填土越厚,相应土洞临界深度越大。 相似文献
6.
综合运用跨孔地震CT、探地雷达、高密度电阻率法、浅层地震反射波、土壤氡浓度和波速测试6种物探方法,对广州市白云区金沙洲岩溶地面塌陷、地面沉降地质灾害进行探测,查明了该区的溶洞、土洞及构造破碎带的分布。介绍了各种方法技术,对综合物探成果进行总结,结合实例说明综合物探方法在该区的应用取得了显著效果,为地质灾害防治提供了基础地质资料。在广花盆地岩溶发育区,首次应用跨孔地震CT探测建筑物地下岩溶分布,为评价受岩溶地质灾害影响的建筑物安全提供依据。 相似文献
7.
Mechanism of sinkhole formation during groundwater-level recovery in karst mining area,Dachengqiao, Hunan province,China 总被引：1，自引：0，他引：1
Zongyuan Pan Xiaozhen Jiang Mingtang Lei Zhende Guan Yuanbin Wu Yongli Gao 《Environmental Earth Sciences》2018,77(24):799
The Meitanba Coal Mine area in Hunan province, China, had been impacted by severe cover collapse sinkholes since 1982 due to mine dewatering. After the coal mine was closed in February 2015, the groundwater level has increased significantly. A series of sinkholes were recorded in the study area during groundwater-level recovery. Analysis of monitoring results and in-situ investigation indicated that 13 sinkhole collapses were more likely induced by abrupt change of groundwater–air pressure in response to heavy rainfall from March 2015 to July 2016 when the groundwater level increased by as much as 76 m. When the karst conduit was flooded, a relatively sealed environment was formed between saturated sediments and flooded karst conduit. Implosion of entrapped air might have caused the cave roof to collapse followed by surface collapses in a short time. On the other hand, four sinkholes occurred in November 2016 when the groundwater levels were near the soil–bedrock interface at elevations between 52.5 and 58.9 m amsl and the groundwater-level increase was at slower paces. Field measurements indicate that the groundwater-level fluctuation at the soil–bedrock interface could enlarge the soil cavity and accelerate the subsoil erosion process. 相似文献
8.
Chemseddine Fehdi Fethi Baali Djamel Boubaya Abdelkader Rouabhia 《Arabian Journal of Geosciences》2011,4(1-2):181-187
Sinkhole collapse is one of the main limitations on the development of karst areas, especially where bedrock is covered by unconsolidated material. Studies of sinkhole formation have shown that sinkholes are likely to develop in cutter (enlarged joint) zones as a result of subterranean erosion by flowing groundwater. Electrical resistivity imaging or tomography (RESTOM) is well suited to mapping sinkholes because of the ability of the technique for detecting resistive features and discriminating subtle resistivity variations. Two-dimensional electrical resistivity tomography surveys were conducted at two sinkhole sites near Cheria city where limestone is covered by about 10 m of clayey soils. A Wenner transect was conducted between the two sinkholes. The electrode spacing was 2 m. The length of transect is about 80 m. The survey results suggest that RESTOM is an ideal geophysical tool to aid in the detection and monitoring of sinkholes and other subsurface cavities. 相似文献
9.
I. Nouioua Aek. Rouabhia Ch. Fehdi M. L. Boukelloul L. Gadri D. Chabou R. Mouici 《Environmental Earth Sciences》2013,68(6):1661-1672
Sinkhole collapse is one of the main limitations in the development of karst areas, especially where bedrock is covered by unconsolidated material. Studies of sinkhole formation have shown that sinkholes are likely to develop in cutter (enlarged joint) zones as a result of subterranean erosion by flowing groundwater. Ground-penetrating radar (GPR) and electrical resistivity imaging or tomography (RESTOM) are well suited to mapping sinkholes because of the ability of these two techniques for detecting voids and discriminating subtle resistivity variations. Nine GPR profiles and two-dimensional electrical resistivity tomography have been applied, with relative success, to locate paleo-collapses and cavities, and to detect and characterize karst at two sinkhole sites near Cheria City where limestone is covered by about 10 m of clayey soils. The survey results suggest that GPR and RESTOM are ideal geophysical tools to aid in the detection and monitoring of sinkholes and other subsurface cavities. 相似文献
10.
云南高原岩溶塌陷总的特征是由岩溶高原特定的地质环境、岩溶发育、水文地质以及水文气象和人类工程活动等因素综合影响和决定的,文中通过对这些因素及其作用机制的分析,深化了对高原岩溶塌陷基本特征和发育规律的认识。云南高原岩溶塌陷区域上分布零星,地段上呈现“点状”特征,主要集中发育于岩溶断陷盆地、岩溶槽谷（洼）地、岩溶台地或古高... 相似文献
11.
Erosion-creep-collapse mechanism of underground soil loss for the karst rocky desertification in Chenqi village,Puding county,Guizhou, China 总被引：10，自引：1，他引：9
Jianxiu Wang Baoping Zou Yan Liu Yiqun Tang Xinbao Zhang Ping Yang 《Environmental Earth Sciences》2014,72(8):2751-2764
Carbonate rocks distribute widely in China. The total area of the carbonate rocks is about 3,430,000 km2, and the exposed area of the carbonate is approximately 13 % of China’s territory. In 2003, soil loss in Yunnan, Guizhou, and Guangxi provinces reached 179,600 km2, which is almost 40.1 % of the total area, causing rocky desertification. In this study, the erosion-creep-collapse mechanism of underground soil loss for the karst rocky desertification in Chenqi village, Puding county, Guizhou province is proposed. The mechanism occurs under the following geological environment: slope surface undulation, underlying bedrock surface fluctuation and thin and inhomogeneous soil overlying, overlying soil generation by bedrock weathering, underground karst development, and large groundwater depth and lying water table under the bottom of soils. The erosion-creep-collapse mechanism of underground soil loss in the karst slopes is explained as follows: power loss due to human cultivation activities that destroy the soil structure, hydraulic force formed by rainfall infiltration, wet–dry cycle generated by rainfall, erosion effect caused by rainfall penetration, creeping and flowing of plastic-stream soil, and collapse. The erosion-creep-collapse mechanism of underground soil loss has seven steps: disturbance of soils filled in underground karst cave by human activities, internal soil erosion and partial collapse caused by hydraulic power, internal free surface formation within the soil in the filled karst cave, internal soil creeping, soil pipe formation, soil pipe collapse, and ground surface collapse and filling. Soil loss develops slowly, and sudden transportation occurs by collapse. Soil loss can be explained by the proposed mechanism, and soil loss can be prevented by controlling soil collapse. 相似文献
12.
On June 3, 2010, a series of karst sinkholes occurred at Jili village surrounded by Gui-Bei highway, Wu-Ping highway and Nan-Liu High-Speed Railway in Laibin, Guangxi, China. The straight-line distances from an large sinkhole pit, 85 m in diameter and 38 m in depth, to the above mainlines are 200, 600 and 500 m, respectively. Several investigation methods including geophysical technology, borehole and well drilling, groundwater elevation survey and hydrochemistry analysis of groundwater were used to study the formation mechanisms of these sinkholes. Based on the results, the spatial distribution of the Jili underground river was confirmed with a strike of SN along the middle Carboniferous limestone bedrock and the Quaternary deposits controlled the sinkhole formation. In addition, both historical sinkhole events and analysis of the groundwater–air pressure monitoring data installed in the underlying karst conduit system indicate that sinkholes in this area are more likely induced by extreme weather conditions within typical karst geological settings. Extreme weather conditions in the study area before the sinkhole collapses consisted of a year-long drought followed by continuous precipitation with a daily maximum precipitation of 442 mm between May 31 and June 1, 2010. Typical geological conditions include the Jili underground river overlain by the Quaternary overburden with thick clayey rubble. Especially in the recharge zone of the underground river, a stabilized shallow water table was formed in response to the extreme rainstorm because of the presence of the thick clayey rubble. When the underground conduit was flooded through the cave entrance on the surface, air blasting may have caused the cave roof collapse followed by formation of soil cavities and surface collapses. Borehole monitoring results of the groundwater–air pressure monitoring show that the potential karst sinkhole can pose threats to Shanbei village, the High-Speed Railway and the Wu-Ping highway. Local government needs to be aware of any early indicators of this geohazard so that devastating sinkholes can be prevented in the future. The results also suggest that groundwater–air pressure monitoring data collected both the Quaternary deposits and the bedrock karst system provide useful indicators for potential sinkhole collapses in similar karst areas where sinkholes usually occur during rainy season or karst groundwater level is always under the rockhead. 相似文献
13.
瞬态瑞雷面波法勘探中,掌握隐伏溶洞的响应特征是进行野外探查分析的基础。结合两类填充状态隐伏溶洞,使用有限差分法进行数值模拟,分别构建不同发育介质溶洞模型。并利用贵广铁路隐伏溶洞探测实例验证探测效果。分析认为:瑞雷面波法对面波相速度差异反映敏感,精度较高,对基岩面和两种类型隐伏溶洞分辨率高;对于填充溶洞,速度响应由溶洞中充填介质的物性决定,一般为低速反映;对于空溶洞,速度较粘土层及基岩均为低速反映;两种溶洞探测面波频散曲线在溶洞位置都会出现较为形象明显的“之”字形拐曲。取得的结果可为工程应用提供借鉴。 相似文献
14.
某岩溶矿山电耙机基座塌陷形成条件及治理技术 总被引：1，自引：1，他引：0
某电耙机基座位于南方某岩溶矿山,地基由粉质黏土、卵石及壶天群灰岩组成。2009年6月发生塌陷,平面上塌陷坑长约3 m,短约2 m,造成电耙机大部被埋入溶洞内,严重威胁到周边尾砂堆场及水泥罐的安全。调查分析及土洞塌陷过程模拟表明,该电耙机基座塌陷主要由于壶天群灰岩溶蚀裂隙发育强烈,地下水位在岩土界面附近上下波动,以及日常生产中电耙机基础旁长期受冲水综合作用,致使基岩面上的土层颗粒被潜蚀带出进而形成土洞坍塌。针对以往塌陷治理多以回填为主,复塌比较频繁,本电耙机基座塌陷采用孔内旋喷造浆注浆方法处理,即先根据孔深的不同向水泥浆中添加不同比例的速凝剂,然后将添加速凝剂的水泥浆液快速送入孔内,并利用高压和高转速切割周边土层,使得单纯的水泥浆成为水泥黏土浆液,在高压下浆液劈裂土层,从而达到快速封堵溶洞口和加固土层的目的。检测结果显示,该方法不仅能有效快速地封堵基岩面溶蚀裂隙或溶洞口并加固土层,消除塌陷的基本条件,而且工艺成熟,成本远小于注浆加固,适合在岩溶矿区推广应用。 相似文献
15.
岩溶地面塌陷是岩溶发育地区常见的地质灾害类型。岩溶塌陷对基础设施和人民生命财产安全构成极大威胁。文章以贵港市北环新村岩溶地面塌陷灾害为例,采用地质分析与颗粒流离散元数值模拟相结合的方法,研究岩溶塌陷成因与致灾规律。结果表明:本次塌陷是由多类因素共同导致,主要包括地质环境、地下水位波动与管道渗漏及工程建设活动等;白云岩、灰岩差异性风化所形成的粉砂质土极易诱发土洞与岩溶塌陷灾害;塌陷灾害可分为土洞形成阶段、土洞发展阶段和土洞塌陷阶段,其土洞规模、形状及影响存在显著差别;土洞形成发展过程中,地表沉降量从塌陷中心向四周逐渐减小,存在明显的沉降敏感区,塌坑边缘的竖向临空面存在拉应力作用,极易再次诱发塌陷。研究成果可为岩溶地面塌陷灾害防控与预警提供一定的理论参考。 相似文献
16.
无锡某地基埋藏型岩溶发育特征及充填物来源 总被引：1，自引：1，他引：0
研究埋藏型岩溶的发育特征和充填物来源对拟建超高层建筑的选址及持力层的选择具有重要意义。本文通过跨孔地震CT对溶洞和破碎带进行探测,并对部分代表性溶洞的充填物进行比重试验、颗粒分析和X射线衍射分析,结合现场工程地质情况,研究了距地表以下80余米处岩溶的规模、分布情况、岩溶发育特征及溶洞充填物来源。结果表明:溶洞发育规模较小,面积多在2m2以下,在垂直方向具有多层性;溶洞充填率达到92.7%,多为硬塑泥质全充填,承载力较大,可作为基础持力层;溶洞填充物的矿物成分基本相同,且与上覆基岩一致,充填物来源主要为上覆基岩的剥蚀;溶洞之间不存在大的连通通道,且地下水位已降至场地溶洞以下,故该处溶洞不会进一步发育,不会对上部地基稳定性造成威胁。 相似文献
17.
高密度电法与微动技术组合在岩溶塌陷分区中的应用分析——以广西来宾吉利塌陷为例 总被引：7，自引：5，他引：2
为了验证物探技术在岩溶塌陷调查中的应用效果,本文于广西来宾市吉利村开展了高密度电法和微动技术野外探测研究。结果表明:高密度对称四极电测深能直观地反映第四系覆盖层的厚度和低阻异常的深度,微动技术能定性地判定地下暗河和岩溶破碎带在地表的平面投影,将两种方法相结合能更加准确地圈出塌陷,以及引起塌陷的溶洞、地下河、断层破碎带及软土分布范围。地下暗河或岩溶破碎带在高密度联合剖面法上反映为低阻正交点异常,极距为45 m时正交点附近电阻率值约为250 Ω?m;在微动H/V比值谱上反映为H/V极大值异常,极大值特征频率在2~6 Hz之间。依据2测线上的高密度电法和微动异常显示,圈出了两个易塌陷区,经对其中的一异常进行钻探验证,异常区覆盖层下42 m 厚的灰岩地层中钻遇溶洞8个,其中最大的高达5.7 m。 相似文献
18.
Sinkhole collapse is one of the main limitations on the development of karst areas, especially where bedrock is covered by
unconsolidated material. Studies of sinkhole formation have shown that sinkholes are likely to develop in cutter (enlarged
joint) zones as a result of subterranean erosion by flowing groundwater. Because of the irregular distribution of pinnacles
and cutters on the bedrock surface, uncertainties arise when "hit-or-miss" borehole drilling is used to locate potential collapse
sites. A high-resolution geophysical technique capable of depicting the details of the bedrock surface is essential for guiding
the drilling program. Dipole-dipole electrical resistivity tomography (ERT) was used to map the bedrock surface at a site
in southern Indiana where limestone is covered by about 9 m of clayey soils. Forty-nine transects were conducted over an area
of approximately 42,037 m2. The electrode spacing was 3 m. The length of the transects varied from 81 to 249 m. The tomographs were interpreted with
the aid of soil borings. The repeatability of ERT was evaluated by comparing the rock surface elevations interpreted from
pairs of transects where they crossed each other. The average difference was 2.4 m, with a maximum of 10 m. The discrepancy
between interpreted bedrock-surface elevations for a transect intersection may be caused by variations in the subsurface geology
normal to the transect. Averaging the elevation data interpreted from different transects improved the ERT results. A bedrock
surface map was generated using only the averaged elevation data at the transect junctions. The accuracy of the map was further
evaluated using data from four exploratory boreholes. The average difference between interpreted and actual bedrock surface-elevations
was less than 0.4 m. The map shows two large troughs in the limestone surface: one coinciding with an existing sinkhole basin,
while the other is in alignment with a small topographic valley. Because sinkholes were observed at the same elevation interval
in similar valleys in the vicinity, the delineated trough may have implications for future land use at the site.
Received: 4 January 1999 · Accepted: 8 March 1999 相似文献
19.
I. Camilo Higuera-Díaz Philip J. Carpenter Michael D. Thompson 《Environmental Geology》2007,53(4):805-812
Karst aquifers are highly susceptible to contamination, with numerous points of entry for contaminants through recharge features
such as sinkholes, swallow holes and solutionally enlarged fractures. These recharge features may be filled or obscured at
the surface, requiring the use of geophysical or remote sensing techniques for their identification. This study uses seismic
refraction data collected at the Ft. Campbell Army Airfield (CAAF), Kentucky, USA, to test the hypothesis that refraction
tomography is a useful tool for imaging bedrock depressions beneath thick overburden (greater than 20 m of unconsolidated
sediment). Southeast of the main taxiway of CAAF seismic velocity tomograms imaged a bedrock low, possibly a closed depression,
at a depth of 25 m that had been earlier identified through delay-time analysis of the same refraction data. Tomography suggests
the bedrock low is about 250-m wide by 10-m deep at its widest point. High rates of contaminant vapor extraction over the
western extension of this feature suggest a high concentration of contaminants above, and within, this filled bedrock low,
the base of which may contain solutionally enlarged fractures (i.e. karst conduits) that could funnel these contaminants to
the upper or lower bedrock aquifers. This study thus demonstrates the viability of seismic refraction tomography as a tool
for identification of filled sinkholes and bedrock depressions in karst areas. 相似文献
20.
Empirical correlation between standard penetration resistance (SPT-N) and shear wave velocity measured by seismic downhole techniques are prepared of the alluvial soil of quaternary age for the Kanpur city. The Kanpur city is having seismic threat from Himalaya and it falls in seismic zone III according to seismic zones of India. Standard penetration test as well seismic downhole test has been carried out up to 30 m at twelve different locations of Kanpur city. The measured SPT-N values and shear wave velocity values are used to develop empirical correlation between SPT-N and shear wave velocity. The proposed correlations have been compared with the existing regression equations by various other investigators. It is found that the proposed correlation exhibit good performance (10 % error bar). Also the measured shear wave velocity has been used to prepare spatially distributed contour map of 50, 75 and 100 m/s using ArcGIS-9 software. It is observed that the shear wave velocity values for the northern part of Kanpur city vary from 125 to 825 m/s. In southern part, it is varying from 125 to 500 m/s where as in the central part of the city the shear wave velocity varies from 125 to 375 m/s. The eastern part of the city also shows some variation in shear wave velocity which ranges from 250 to 625 m/s. The western part of the city shows the variation of shear wave velocity from ≤125 to 500 m/s. The soil type of the study area are classified as per NEHRP and new Italian O.P.M.C classification system as B, C and D type soil with having site period of 0.1–0.9 s and Poisson’s ratio varying from 0.1 to 0.4. 相似文献