Evaluation of Karst Hazards for Civil and Industrial Buildings

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.

Risk Assessment for Karst Hazards at a Facility in Saudi Arabia—A Case Study

The boom in industrial and infrastructure construction in Saudi Arabia requires in-depth knowledge of the underground conditions to build a sustainable project. This paper gave a practical example of the challenges facing an existing facility built on a karstic limestone formation in 1970’s. Multiple geophysical techniques such as Microgravity, Electrical Resistivity Imaging, Vertical Seismic Velocity Profiling, Cross Hole Seismic Tomography, Ground Penetration Radar, Multi-Channel Analysis of Surface Waves, as well as boreholes and down-hole video imagery, were deployed through the journey of assessing the karst associated hazards of potential sinkholes or general subsidence. This paper described the karst processes, site geology, geophysical and geotechnical exploration program, and characterizes the subsurface karst conditions at the eastern province of Kingdom of Saudi Arabia. Results and findings of preliminary, geotechnical and geophysical investigations have been utilized to identify the major factors influencing the karst formation. Analyses and integration of obtained results to estimate the type and magnitude of risk affected the major components of industrial facility at the project site using well-known statistical approach were presented in this paper. Consequently number of remedial measures implemented to combating the experienced and expected karst hazards at the studied industrial facility placed in karstified landform are given. A model for using integrated geophysical and geotechnical techniques to assess karst-related risks to a facility was further explored herein.

Hazards and Landscape Changes(Degradations) on Hungarian Karst Mountains Due to Natural and Human Effects

In order to study the karstological processes within the karst ecological system,the geohazards and degradation of karst landscapes on the karst areas of the Bakony mountains(Hungary),we investigated the abiotic elements of the environment,soil and cover deposits,erosion soil decay;the changes in the quantity and quality of karst waters:contamination at swallow holes,contamination of karst springs;and the biogenic factors:surface vegetation coverage by the corine land cover method,plant-ecological examinations,qualification of surface waters with the help of biological water labeling.We recognized that the increasing human activities during the past few centuries have had significant impact on the investigated landscapes of karst areas because of their spatial sensitivity.In the scope of our research we concluded that the landscape changes due to natural and human effects can vary strongly on the different karst areas.These differences can arise from the climatic and geomorphologic situation,the coverlayer's qualities,etc.,but primarily from the different utilization of the investigated karst areas(e.g.the intensity,characteristics and territorial extension of utilization).On the spot investigation we detected traces of new and fast geomorphological processes(gully formation,landslides,collapses,new sinkhole development) and landforms(sinkholes,gullies,swallow holes),which are clear evidences of the effect of climatic changes.

Palaeoseismic Events in Karst Terrains along the Northern Bulgarian Black Sea Coast

The study of the palaoseismic events in the karst terrains of the Bulgarian Black Sea coast is a very important up-to-date problem. The investigated region is one of the highest-energy regions in Bulgaria with established and recorded catastrophic historic and contemporary earthquakes. The terrain is subjected to the influence not only of its own earthquake foci but also of those in Romania and Russia. The palaeoearthquakes that caused considerable disturbances in the karst terrains along the Northern Bulgarian Black Sea coast have left significant traces. They caused disturbances in the environment and the relief (rearrangement of the surface and ground water karst basins, partially or entirely collapsed caves, deformed caves, oil, gas and salt intrusions and gravitationally formed caves). The ecological consequences in historic and contemporary aspects were catastrophic. The palaeoseismic dislocations were formed as a result of global, regional and local geodynamic events related with the destruction of the Moezian platform and the regional extension of the Black Sea basin. The time of their display and their spatial interrelations were established as a result of complex investigations accompanied by original documents.

Influence of droughts on remote villages in the karst region of Guizhou Province, China: Causes and control

Even though the precipitation is abundant in the Karst region of Guizhou Province, remote villages in this area frequently suffer severe droughts. This paper studied the causes of droughts in this region through field investigation and references collection. Based on the cause analysis, some suggestions were provided for hazard prevention and control from an engineering perspective. Besides occasional extreme weathers, the drought in this area is primarily caused by its unique geological structures of Karst plateau and underdeveloped agricultural techniques. Meanwhile, the vicious cycle between drought and poverty, which causes the deficiency of water conservancy facilities and hazard prevention awareness, is an important reason for the frequent occurrence of agricultural and socioeconomic drought. Considering the social and economic conditions of remote villages, the long-term control of drought can only be realized if current measures are capable of bring immediate effects and benefits. Therefore, the construction of well-planned and designed water conservancy system based on each village's natural and social conditions are the priority for current hazard prevention. Generally, the exploitation of subterranean river should be considered as the first choice to stabilize the water supply for remote villages. Meanwhile, the construction and improvement of micro water conservancy facilities, such as small water tank, small pond and so on, can effectively support the water providence during droughts as well.

Geospatial Modeling for Sinkholes Hazard Map Based on GIS &RS Data

The Kinta Valley is an area of karst in the north-western part of Peninsular Malaysia. Over 30 years of uncontrolled land use and development has led to significant changes in topography and geomorphology, such as the appearance of sinkholes. In this paper, geospatial techniques were utilized to the task of evaluating sinkholes susceptibility map using a spatial multi criteria evaluation approach (SMCE). Sinkhole location and a spatial database were applied to calculate eight inherent causative factors for limestone instability namely: lithology, structure (lineament), soil cover, slope, land use mining, urban area features, ponds and rivers. The preparation of the sinkhole geohazard map involved summing the weighted values for each hazard element, which permits the construction of geohazard model;the results of the analysis were validated using the previous actual sinkholes locations in the study area. The spatial distribution of sinkholes occurrence, urban development, faults distribution and ex-mining ponds are factors that are directly responsible for all sinkholes subsidence hazards. Further, the resulting geo-hazard map shows that 93% of recent sinkholes occur in areas where the model flags as “high” and “very high” potential hazard, located in the urbanized part of the valley, while less-developed areas to the west and southwest suffered less sinkhole development. The results can be used for hazard prevention and land-use planning.

贵州省饱和水汽压差时空变化特征与影响因素

饱和水汽压差(VPD)是表示区域大气干燥程度的重要指标,分析贵州省VPD时空变化特征及其影响机制对明晰气候变化规律和农业生产具有重要意义。研究基于中国气象局提供的CN05.1格点化观测数据集,量化并分析了1961—2022年贵州省喀斯特区域和非喀斯特区域VPD及其时空变化特征,采用多元线性回归方法识别了影响VPD变化的主要气象要素并分析了基于VPD的干旱危险性。结果发现:贵州省年际和季节尺度VPD存在显著的升高趋势,其中喀斯特区域和非喀斯特区域春季和夏季VPD空间分布和变化趋势均呈现相反的格局;以VPD为指标的贵州省干旱危险性显著升高,非喀斯特区域速率更快;气温和相对湿度是贵州省年际和季节尺度上VPD变化的主导气象要素,不同区域年和季节尺度上不同气象要素的贡献率稍有差异。

岩溶区地下水数值模拟分析及开采方案比选

数值模拟是解决地下水开采评价问题的有效途径之一。为安全高效开发岩溶塌陷区地下水资源,以山东省临沂市岩溶区为例,根据水文地质调查分析,充分掌握了岩溶区地下水补给规律、运移规律、分布规律,在此基础上,选取合理模拟范围,建立数值模型,开展多方案地下水动态演化数值预测分析,据此来分析评价最优开采方案。研究结果表明:方案一岩溶塌陷危险性较高,数值观测孔水位在第1279 d、第1644 d、第2019 d和第3105 d时,水位降至灰岩顶板标高39.9 m以下,将引发岩溶塌陷风险;方案二则较安全,数值观测枯水期水位接近灰岩顶板标高,既达到地下水开发利用潜力的标准,又可保证生态地质环境安全,因此,建议采用方案二。开采过程中预警区水位应位于基岩顶板标高以下,以避免岩溶塌陷发生。本文研究结果可为类似塌陷区的科学开采提供参考。

武汉大桥条带东段地区岩溶发育特征

为探究大桥条带东段岩溶发育特点和岩溶顶板厚度规律,总结岩溶裂隙水类型及补给规律,建立考虑注浆量和充填情况因素的岩溶分类模型。通过统计分析和K-means聚类分析等方法研究了研究区岩溶规律。结果表明:存在严重漏水的溶洞占44.44%,轻微漏水~漏水占18.52%,不漏水占37.04%,溶洞填充物处于软塑状态的占36.54%,流塑-软塑状态占26.92%,可塑状态占19.23%,其余状态占17.31%。注浆量与状态系数呈负相关关系,与溶洞高度和顶板厚度呈正相关关系,溶洞高度对注浆量影响最大。小于某溶洞洞高值对数值和溶洞个数呈线性函数关系,小于某顶板厚度概率实测值和顶板厚度满足三次函数关系;溶洞未填充占12.16%,半填充占9.46%,完全填充占78.38%;见洞率25.52%,平均线岩溶率7.69%,平均洞高2.87 m, 1/3的洞高度小于1.4 m, 1/2的洞高度小于2.2 m, 90%的洞高小于5.5 m,溶洞以竖向发育为主,单位溶洞高度注浆量为0.88 m^(3);研究区岩溶裂隙水为HCO_(3)-Na·Ca型水体,岩溶裂隙水主要补给来源于孔隙水;采用K-means聚类算法开展评估和分类,将溶洞划分为两类:第一类注浆量平均值为24.50 m^(3),填充物状态系数平均值为0.38,溶洞高度平均值为2.32 m;第二类注浆量平均值为2.36 m^(3),填充物状态系数平均值为0.57,溶洞高度平均值为5.98 m,轮廓系数为0.84,分类模型该精度较高,该模型可用于解释溶洞空间上的发育等情况。

水文地质条件极复杂矿井底板岩溶水害强化注浆加固应用与效果分析

为保障矿井安全生产、延长矿井使用寿命、减少生产成本和保护环境。针对水文地质条件极复杂矿井底板岩溶水害治理难题,研究强化注浆加固技术的应用效果。结合121103工作面实际工程,通过对矿井地质构造和水文地质条件的详细分析,制定科学的注浆加固设计方案,采用注浆钻孔布置和井下钻孔探查方法,根据设计要求对奥灰顶部和徐灰进行强化注浆综合治理。并在实施注浆加固工程后,监测注浆终压、钻孔注浆覆盖率、块段吨水注干料数等指标,并通过检查孔和井下物探方法评价改造效果。结果表明,奥灰顶部和徐灰的强化注浆改造均取得显著成效,注浆终压达到预期标准,钻孔注浆覆盖率和块段吨水注干料数达到设计要求,检查孔分析和井下物探结果显示,水害问题得到有效控制,矿井安全生产条件显著改善。

视电阻率法在隐伏岩溶灾害调查中的应用

隐伏岩溶发育引起的地面塌陷和地裂缝等地质灾害频繁发生,提高勘查方法和解译精度在隐伏岩溶区灾害调查中尤为重要。视电阻率法数据处理、反演算法以及综合解译方法的进步为地质灾害调查提供了有力手段。本文引入视电阻率三维模型,结合二维剖面分析,对采集的视电阻率数据进行综合整理,丰富了数据处理方法,提高了数据模块关联性,有效提高了解译精度和地质模型契合度。结合钻探验证情况对泰安市桥沟地区隐伏岩溶塌陷区进行分析研究,通过隐伏岩溶发育区的视电阻率特征,分析岩溶发育范围和成因,为隐伏岩溶区灾害调查提供了良好的地球物理应用和参考价值。

喀斯特地貌区公路岩质边坡地质灾害评估方法研究

作为喀斯特地貌的典型分布区,广西在公路工程中有大量的岩质边坡产生和存在,而岩质边坡稳定性评价亦是公路工程建设项目地质灾害评估最为关注的问题。赤平投影法作为一种常见的定性或半定量分析方法,目前已被应用于部分边坡工程中,但在公路工程地质灾害评估中应用仍不够普及,本文通过赤平投影法进一步丰富地质灾害评估中对于岩质边坡的评价方法,并结合工程实例对此方法进行研究和探讨。

广州市江府-桃源中间风井工程地质条件评价

研究城市地下空间基本地质结构对城市地下交通具有重大意义。本文以广州市江府-桃源中间风井地质勘探为例,开展工程地质条件评价,预测该工程项目可能在施工和完工阶段引发或加剧基坑边坡不稳、地面下沉和岩溶塌陷等地质灾害问题。

基于AHP模型的岩溶地面塌陷危险性评价

本文以桐柏县朱庄镇朱庄村岩溶地面塌陷为例,收集了研究区地质环境资料、水文地质资料及工程地质资料,选取基岩岩性、岩溶发育程度、覆盖层厚度、透水能力、水位波动幅度、地下水位埋深六个主控因素,将层次分析法(Analytic Hierarchy Process,简称AHP)确定的权重与GIS处理的各主控因子专题图进行叠加,进而对桐柏县朱庄岩溶地面塌陷进行危险性分区评价。根据与已发生的塌陷对比,验证了AHP-GIS耦合评价在朱庄岩溶地面塌陷危险性评价应用中结果的准确性,已发生岩溶塌陷点几乎都位于高危险区。评价结果可为朱庄岩溶地面塌陷的防治提供参考依据,评价方法对其他岩溶地面塌陷危险性评价具有借鉴意义。

鄂西南清渔河间地块地质特征与铁路选线研究

某拟建铁路地质背景独特,工程地质及水文地质条件复杂,需查明主要工程地质问题,开展基于减灾理念的综合选线研究,针对地质问题采取工程措施规避灾害风险。研究表明:清渔河间地块岩溶与岩溶水系统、环境水文条件、卸荷式地质灾害、页岩气生成与存储等多种地质问题控制铁路通行方案的选择;经专项研究将清渔河间地块岩溶系统细分为5个大区、21个小区,开展人口分布与可利用水资源分级分析,卸荷式地质灾害和页岩气发育规律及影响评价;多方案综合比选,找出可通行方案,提出结合施工组织、环境水文生态保障、工程施工运营风险等多因素统筹考虑的方案研究建议。

隧道岩溶病害危险性分区在超前地质预报中的应用

针对厦蓉高速公路沙井街隧道岩溶的发育特点,提出了"隧道岩溶病害危险性分区"概念,并应用于超前地质预报工作中;根据中导洞开挖揭露的地质条件,对隧道岩溶病害危险性分区进行了修正,以指导主洞的超前预报工作,从而提高了预报工作的针对性并突出了重点;同时,基于高密度电法对不同介质电阻率的敏感性,在预报方法上将地表高密度电法与洞内地质雷达法相结合,提高了对重大岩溶病害预报的准确性。实际开挖结果显示:超前地质预报结果与实际情况高度吻合。

宜万铁路岩溶地质特征及其发育模式

宜万铁路沿线地形、地质条件复杂,是目前已建和在建铁路中岩溶最发育的工程。宜万铁路全线设计隧道159座,其中全线洞身穿越可溶性岩层的隧道由91座。隧道施工中不可避免的遭遇到岩溶的不利影响,造成隧道突水、泥等岩溶灾害的发生,带来了重大安全危害和经济损失,成为亟待解决的重要问题。本文通过对全线岩溶发育特征、地下岩溶形态的分析,依据典型岩溶隧道实例,对隧道与岩溶的位置关系进行了分类,并探讨了宜万线岩溶隧道的主要岩溶灾害,在此基础上将隧道中的岩溶发育特征概化为四种基本模式,为采取定量分析方法分析岩溶隧道突水、突泥及岩层垮塌机理,得到规律性的认识提供支持。

探地雷达探测潜在喀斯特地面塌陷区的可行性研究

在中国分布很多的喀斯特地区,由岩溶引起的地面塌陷已经成为一种环境灾害。为了探明潜在的喀斯特岩溶塌陷地区,我们引入了探地雷达测量技术。在华中107国道附近的北丰桥地区,使用探地雷达进行的可行性试验表明,探地雷达可以探明地下变形和扰动信号,从而确定出潜在的喀斯特地面塌陷区。

三峡库区巫山县翠屏小区岩溶引起的地质灾害危险性研究

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。巫山县城翠屏小区是较早发现有确切岩溶证据的地方,研究证实小区三叠系嘉陵江组灰岩普遍遭受了强烈的岩溶作用。不同部位具有不同的岩溶特点和强度,在纵向上,从山顶到坡脚岩溶作用有增强的趋势;从地表向深部,有局部强烈岩溶层位。岩溶作用在小区产生了顺坡或顺层延伸的溶洞和深部蜂窝状溶孔。岩溶作用在小区形成了脖颈状溶蚀槽地、槽状谷地、溶蚀台地和与地貌相关的"飞雁状"褶皱、岩溶正断层及帚状密集节理带。岩溶过程中伴随着其他外营力作用,它们的相互耦合形成各种次生岩土体。岩溶轻则引起岩体质量降低,重则可能导致地面不均匀沉降、地裂缝、滑坡、崩塌、泥石流及地面塌陷地质灾害。

隧道及地下工程岩溶危害预报的专家系统

在碳酸盐岩类地区修建铁路或公路隧道以及其它各种类型的地下工程时,可能遇到岩溶水突入、涌沙以及洞室坍塌等岩溶地质现象造成的危害。本文根据国内岩溶专家的经验制成专家系统,以便根据具体的水文地质和工程地质勘测资料,对工程所选定的位置和通过的地区的岩溶现象可能对工程发生的危害做出分级预报。本系统可在工程选址、设计以及施工过程中作为一个辅助决策系统为决策者提供信息,以减少工程失误,降低工程造价,保证工期。本系统业经有关专家初步验证,此外,本系统亦可供在水工隧道、地下厂房和矿山坑道的岩溶灾害预报工作中使用。