TST技术在岩溶地区隧道超前预报中的应用

顶效隧道位于岩溶发育地区,地质构造复杂,岩体破碎,对超前预报技术的要求高,风险较大。目前国内外应用的隧道超前预报技术多数都存在着技术缺陷,不能区分不同方向的地震回波,不能准确地确定掌子面前方围岩的波速,不能正确地进行纵横波分离等问题,影响到预报的可靠性和准确性。为了确保施工安全,减少和避免地质灾害发生,顶效隧道超前预报中采用了TST技术。应用结果表明,TST技术采用空间阵列系统和速度扫描技术有效地解决了掌子面前方围岩速度分布问题,提高了构造定位精度;应用二维方向滤波技术有效地消除了上下、左右的侧向回波和面波干扰,成功提取了前方回波用于超前预报,避免了虚报误报,解决了复杂地质条件下的超前预报问题。     

我国岩溶塌陷研究综述

随经济的不断发展,对岩溶区资源的开发日益增强,由此引发的岩溶塌陷问题也日趋频繁、严重,已成为岩溶区可持续发展的一大障碍,有效减轻其造成的危害势在必行。文章根据近年来国内外岩溶塌陷的研究现状及发展,概述了岩溶塌陷的三大形成条件:一定发育程度的岩溶、上覆盖层、岩溶地下水系统;以及中国岩溶塌陷的时空分布规律,分别举例例证了它的几种成因机制,如重力致塌、潜蚀致塌等。由于其突发性及危害性,有必要对岩溶塌陷的预测防治进行深入研究,做到防灾减灾。基于此,总结了中国岩溶塌陷的监测预报和安全评价等方面的新方法和措施等。针对塌陷的形成条件、塌陷现象或其危情的存在状况及其危害性,归纳了有针对性的防治措施。     

井间地震层析成像技术在岩溶勘察中的应用

介绍了井间地震层析成像技术测试的工作原理及工作方法,然后利用层析成像反演算法对现场获取的原始测试数据进行了解译,得到溶洞沿不同测线的剖面分布图和不同高程处的平面分布图,并将其与场地现有钻孔地质资料进行对比验证,结果表明井间地震层析成像技术有较高的精度和可信度,可得到场地中溶洞的空间分布,从而为工程设计提供可靠的地质资料。     

广州市白云区岩溶塌陷风险初探

识别出广州白云区岩溶塌陷风险因素,构建岩溶塌陷层次递阶结构模型,运用层次分析法的相关原理计算出基本风险因素对岩溶塌陷风险事件的影响权重。定义极易塌陷区Ⅰ、易塌陷区Ⅱ、次易塌陷区Ⅲ、不易塌陷区Ⅳ和稳定区Ⅴ共5个岩溶塌陷等级分区,建立各基本风险因素5个等级与岩溶塌陷等级分区的对应关系。为实现岩溶塌陷风险的定量评价,定义单因素致塌概率pi,引入伯努利试验建立岩溶塌陷概率计算模型,选取覆盖层厚度、岩溶发育程度、地下水位埋深、基岩岩性、覆盖层结构与底板岩性、地下水开采强度、地下活动强度和地表施工加载与振动等8个基本风险因素参与评价单元塌陷概率计算,并据此确定岩溶塌陷风险等级狭义标准,为区域岩溶塌陷等级分区的划分提供参考依据。岩溶塌陷风险等级分区表明：极易塌陷区集中在分析区内的江村、古楼岗、泉溪、西湖、社岗一带;易塌陷区和次易塌陷区主要分布在江高镇和原石井镇等地带。风险等级分区与白云区已有岩溶塌陷历史统计资料及塌陷危害程度评价结果较为吻合,从而验证了评价方法的有效性。     

On velocity anomalies beneath southeastern China: An investigation combining mineral physics studies and seismic tomography observations

Seismic tomography studies reveal distinct velocity and V_P/V_S anomalies in the mantle transition zone (MTZ) beneath the Yangtze Craton and Cathaysia Block in southeastern China. The anomalies under the Yangtze Craton are characterized by high velocity (both V_P and V_S) and low V_P/V_S ratio, while those beneath the Cathaysia Block are characterized by low velocity (especially V_S) and high V_P/V_S ratio. Here, we conduct analyses of phase relations and thermoelasticity to model the effects of thermal and chemical homogeneities in the MTZ, by taking advantage of recent simultaneous V_P and V_S seismic tomography results under southeastern China. We attempt to quantify the seismic tomography results and examine the effects of temperature, chemical composition, and water (or protonization) on velocity anomalies in the deep mantle. We find V_P/V_S to be a powerful parameter in distinguishing the various effects of temperature, chemical composition, and protonization. We conclude that an ancient stagnated oceanic slab is most likely the main cause of the observed fast velocity and low V_P/V_S anomalies in the MTZ under the Yangtze Craton. This ancient slab material is most likely a product of paleo Pacific subduction around 100–125 Ma ago, when the oceanic plate abruptly changed its direction of motion. Such an event has been shown to be closely related to the magmatic activities around eastern China, the ultrahigh-pressure metamorphism zone between the Yangtze Craton and the North China Craton, and the destruction of the lower crust of the North China Craton. The anomalies under the Cathaysia Block, on the other hand, are likely due to dehydration-induced partial melting of subducted Pacific slab materials. Here the large low V_S anomaly in MTZ coincides with the extensive Mesozoic to Cenozoic igneous features on the surface, suggesting a state with lower viscosities in the upper mantle. Dehydration-induced partial melting in MTZ may have also promoted deformation of the South China fold belt. Our results suggest that these lithospheric processes are directly related to the tectonic interaction between the oceanic and continental plates in southeastern China and that a better understanding of past deep mantle dynamic processes may place important constraints on the evolution of the cratons in China.     

高密度电法在柳州太阳村镇岩溶塌陷区调查中的应用研究

为了查明柳州太阳村镇岩溶塌陷形成的地质背景,本文采用高密度电法对该塌陷区进行调查研究。研究结果表明:高密度电法对于确定土层的厚度,区分土层和岩石的分界面具有较好的效果,通过电阻率的分布及变化趋势,可以较好的圈定地下岩溶裂隙带的发育位置,结合地质资料,对识别断裂破碎带也有较好的效果。三个塌陷区的致塌地质背景不尽相同:第Ⅰ,Ⅲ塌陷区塌陷的形成与人类活动密切相关,分别由机井抽水及输油管道铺设引发;第Ⅱ塌陷区塌陷的形成与自然因素相关,由断裂破碎带触发。通过高密度电法反演结果断面图,能较准确地查明塌陷的潜伏隐患区:第Ⅰ塌陷区的隐伏区为通过抽水井的近东西向的岩溶裂隙带,第Ⅱ塌陷区地质灾害的潜伏区为断层西侧的岩溶裂隙带,第Ⅲ塌陷区的隐患区为输油管道附近东侧的岩溶裂隙带,均位于人类活动频繁附近地段及构造发育带。     

综合物探方法在广州市金沙洲岩溶地面塌陷、地面沉降地质灾害调查中的应用

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。     

New advances in karst collapse research in China

Until 2000, more than 1,446 karst collapse events and 45,037 sinkhole pits have been documented in China. In this paper, focusing on new achievements of karst collapse research in China, a large-scale model experiment, a method of risk assessment and data management of karst collapse based on geographic information system technology are introduced for the region.     

综合物探法在柳州泗角村岩溶塌陷区调查中的应用

岩溶塌陷往往具有不确定性,隐蔽性及突发性。基于岩溶塌陷的上述特点,文章选取高密度电法、主动源面波法、微动法对泗角村岩溶塌陷区进行综合研究,结果表明:高密度电法能较好地的区分岩土层界面及划分岩溶发育带,但分辨率较低;主动源面波法能较好划分岩土层界面且分辨率较高,但探测深度浅;微动法能较精准地确定岩溶塌陷位置,但抗干扰能力较弱;高密度电法、主动源面波法及微动法结合才能有效查明塌陷区内岩土层结构、确定岩溶发育带位置,并预测划分出塌陷危险区、塌陷潜伏区和相对稳定区,为后续灾害治理工作确定具体范围,给治理施工设计提供科学依据;另外,通过对高密度电法、主动源面波法及微动法解译异常特征的分析,查明了塌陷区塌陷的形成和机井的长年抽水有关。     

Investigation of karst collapse based on 3-D seismic technique and DDA method at Xieqiao coal mine, China

Karst collapse is a serious geological problem in most of the coal mines in the north of China, but recently it has been found in the south as well. The present study is aimed at investigating subsidence mechanism and deformation field of a karst collapse column at Xieqiao, in the south of China. A method of three-dimensional (3-D) seismic technique has been successful in exploring the spatial morphology of the karst collapse at Xieqiao, and the discontinuous deformation analysis (DDA) method is used to calculate the deformation field and analyze the subsidence mechanism. The results indicated that DDA could approximately simulate and back analyze the subsidence process and strata deformation fields. The subsidence processes of the collapse column depend on the sizes of the karst caves. With the continuous expansion of the karst caves, a semi-elliptic stress field, local separation strata and fracture zone will be formed around the karst cave. Moreover, they will gradually expand upwards along the vertical direction. The paper also indicates that the subsidence failure stage may trigger a sudden collapse of the karst column because of the sudden energy release. Also, it will make a great impact on the vicinity working face so as to cause a rock burst. The effects of the friction angle of rock strata on the subsidence mechanism were reported firstly based on DDA.     

华北型煤田岩溶陷落柱研究70年: 成因·机理·防治

河北峰峰矿区辛安矿2021年“10·25”小煤窑区奥陶系灰岩(简称奥灰)突水,导致矿井生产水平被淹,矿井停产。对事故成因进行了剖析,提出老空区底板奥灰岩溶水突(涌)水概念,总结其区别于采动引发老空透水或底板突水事故的内涵及外延,揭示浅部老空区底板奥灰承压水储能释放动态演化的突水机制。基于区域奥灰岩溶演化史,采用流场分析、数值模拟以及探治工程揭露,确定区域奥灰岩溶强径流带在井田内的展布形态,建立岩溶水动力场模型,应用人工智能及深度学习方法反演辛安矿“10·25”突水时间及空间位置。针对煤矿采空区底板奥灰突水特点及难点,提出流场树靶、探治结合、新旧共治“三位一体”的水害防控技术体系,经过3个阶段治理实践,不仅3个老旧突水点共1 080 m³/h涌水量以及新突水点稳定涌水量3 600 m³/h得到完全封堵,且矿井原正常涌水量2 040 m³/h下降到1 020 m³/h,效果超出预期目标。

     

我国岩溶地面塌陷研究进展与展望

为了解我国岩溶地面塌陷理论和实践的状况,在讨论了岩溶地面塌陷概念的内涵和外延后,全面总结了岩溶地面塌陷在塌陷机理、预测、监测、防治等方面的研究现状,分析了目前存在的问题,概述了近年来研究的新进展,提出了岩溶地面塌陷研究的发展方向。      

Evaluation of karst collapse risks induced by over-pumping and karst groundwater resource protection in Zaozhuang region,China

Based on the comprehensive analysis of factors influencing karst collapse in the Zaozhuang Shili Spring Area, China, this paper establishes a karst collapse risk evaluation model by means of the fuzzy comprehensive evaluation method. Application of the model led to division of the study area into very high risk area, high risk area, average risk area and low risk area; therefore, the karst collapse risk evaluation map of Zaozhuang Shili Spring Area is completed. As preventive measures of karst collapse, the different karst water resource protection areas of Zaozhuang Shili Spring Area are established, and the map for karst water resource protection area of Zaozhuang Shili Spring Area is compiled. The results will be helpful for the strategic planning and decision-making processes associated with exploitation of karst water resources and with prevention and control of karst collapse hazards of this region.     

广州夏茅村岩溶地面塌陷成因机理与塌陷过程分析

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。     

华北东部深部岩溶及煤矿岩溶水害特征

针对我国华北东部煤矿井开采深度迅速增加,矿井岩溶水害日益加重的客观问题,文章分析讨论了深矿井开采的基本概念,通过统计分析,得出中国东部主要煤矿井目前开采深度达到600 m左右且以12 m/a左右的速度向深部延伸的变化趋势。从华北东部地区沉积古地理环境与地壳运动演化史方面分析了该地区厚层奥陶纪灰岩的形成及其后期岩溶发育过程。通过对研究区几个重点矿区揭露的奥陶系灰岩岩溶发育特征在穿层和顺层方向上随深度变化规律的分析,揭示出华北东部主要煤矿区奥陶系灰岩岩溶发育特征在垂向上具有弱-强-弱和顺层方向上随埋深具有由强到弱的变化规律。提出了华北东部煤矿深部开采将面临的岩溶水害问题及其防治水技术思路。     

华北东部深部岩溶及煤矿岩溶水害特征

超前区域注浆是煤层底板灰岩水害防治的有效手段,而注浆工程中的劈裂注浆过程是决定注浆效果的关键环节,但由于对受注灰岩地层裂隙起裂机制认识不清,致使劈裂注浆过程中注浆压力、浆液水灰比等参数缺少有效控制,难以保证注浆效果。针对上述问题,利用颗粒元(Particle Flow Code,PFC)数值模拟软件,考虑浆液水灰比、地应力水平、弱面和裂隙的倾角和宽度等因素,开展奥陶系灰岩顶部劈裂注浆数值模拟计算。结果表明：在弱面和裂隙条件下起裂压力均随浆液水灰比(1∶1、2∶1、3∶1)的增大而减小,随最大主应力与最小主应力差值(9、12、15 MPa)的减小而增大,随弱面或裂隙宽度(3、8、15 mm)及其与最大主应力夹角(30°、60°、90°)的增大而减小;起裂裂隙沿平行于最大主应力方向延展;起裂压力值随弱面与基质强度比(0.30、0.03)的减小而减小,当弱面强度较高时,起裂压力大于裂隙条件下的起裂压力,而且沿着基质起裂;当注浆孔置于弱面两端或裂隙中间时,起裂裂隙沿弱面或裂隙的两端起裂,当注浆孔置于弱面中间位置时,起裂裂隙沿中间位置的基质起裂。研究结果有助于底板水害超前区域改造劈裂注浆的有效控制,指导注浆参数的选取,为解放深部煤炭资源提供技术支撑。

     

岩溶塌陷区刚性桩复合地基技术应用

在覆盖型岩溶地区,地面塌陷是一种常见的地质灾害,人类工程活动特别是大量抽排地下水或深基础施工的扰动都将引发或加剧地面塌陷。在塌陷范围内不允许采用天然地基,对于重要建筑物常采用桩基础;近年来,刚性桩复合地基已开始逐渐推广使用。深圳龙岗中心医院门急诊综合大楼即是一个典型的工程实例,为避免深基坑开挖大量降排岩溶地下水而造成严重的地面塌陷,对地下室的设计做了调整,并针对复杂的岩溶地质条件及发育特征,采用特殊的刚性桩复合地基;文中重点介绍了素混凝土桩复合地基的设计思路、以及成桩过程中的岩溶塌陷的治理措施。     

The effects of karst collapse on the environments in north China

In this paper, a systematic study was completed on the distribution features and origins of karst collapses in north China. There are 65 modern karst collapse areas with 1,416 karst collapse pits and 38 paleo–karst collapse areas with 3,654 paleo-collapse pillars. Modern karst collapses are mainly distributed in the plain region of the east Taihang and Yanshan Mountains and are concentrated in three zones from the west to the east in this region. The regional distribution features of karst collapses in north China are controlled by the boundary of the geological tectonics, condition of soluble rock and the extent of human activities. From the results, three-grade indices have been adopted to establish a classification scheme for karst collapse in north China. The effects of karst collapses on the environments in north China are summarized using a karst collapse classification scheme.