Catastrophe theory-based risk evaluation model for water and mud inrush and its application in karst tunnels

This paper presents a risk evaluation model of water and mud inrush for tunnel excavation in karst areas.The factors affecting the probabilities of water and mud inrush in karst tunnels are investigated to define the dangerousness of this geological disaster.The losses that are caused by water and mud inrush are taken into consideration to account for its harmfulness.Then a risk evaluation model based on the dangerousness-harmfulness evaluation indicator system is constructed,which is more convincing in comparison with the traditional methods.The catastrophe theory is used to evaluate the risk level of water and mud inrush and it has great advantage in handling problems involving discontinuous catastrophe processes.To validate the proposed approach,the Qiyueshan tunnel of Yichang-Wanzhou Railway is taken as an example in which four target segments are evaluated using the risk evaluation model.Finally,the evaluation results are compared with the excavation data,which shows that the risk levels predicted by the proposed approach are in good agreements with that observed in engineering.In conclusion,the catastrophe theory-based risk evaluation model is an efficient and effective approach for water and mud inrush in karst tunnels.

Risk assessment model of tunnel water inrush based on improved attribute mathematical theory

Tunnel water inrush is one of the common geological disasters in the underground engineering construction.In order to effectively evaluate and control the occurrence of water inrush,the risk assessment model of tunnel water inrush was proposed based on improved attribute mathematical theory.The trigonometric functions were adopted to optimize the attribute mathematical theory,avoiding the influence of mutation points and linear variation zones in traditional linear measurement functions on the accuracy of the model.Based on comprehensive analysis of various factors,five parameters were selected as the evaluation indicators for the model,including tunnel head pressure,permeability coefficient of surrounding rock,crushing degree of surrounding rock,relative angle of joint plane and tunnel section size,under the principle of dimension rationality,independence,directness and quantification.The indicator classifications were determined.The links among measured data were analyzed in detail,and the objective weight of each indicator was determined by using similar weight method.Thereby the tunnel water inrush risk assessment model is established and applied in four target segments of two different tunnels in engineering.The evaluation results and the actual excavation data agree well,which indicates that the model is of high credibility and feasibility.

Risk assessment of floor water inrush in coal mines based on MFIM-TOPSIS variable weight model

Floor water inrush is one of the main types of coal mine water hazards.With the development of deep mining,the prediction and evaluation of floor water inrush is particularly significant.This paper proposes a variable weight model,which combines a multi-factor interaction matrix(MFIM)and the technique for order performance by similarity to ideal solution(TOPSIS)to implement the risk assessment of floor water inrush in coal mines.Based on the MFIM,the interaction between seven evaluation indices,including the confined water pressure,water supply condition and aquifer water yield property,floor aquifuge thickness,fault water transmitting ability,fracture development degree,mining depth and thickness and their influence on floor water inrush were considered.After calculating the constant weights,the active degree evaluation was used to assign a variable weight to the indices.The values of the middle layer and final risk level were obtained by TOPSIS.The presented model was successfully applied in the 9901 working face in the Taoyang Mine and four additional coal mines and the results were highly consistent with the engineering situations.Compared with the existing nonlinear evaluation methods,the proposed model had advantages in terms of the weighting,principle explanation,and algorithm structure.

Risk assessment of water inrush in tunnels based on attribute interval recognition theory

Water inrush is one of the most serious geological hazards in underground engineering construction.In order to effectively prevent and control the occurrence of water inrush,a new attribute interval recognition theory and method is proposed to systematically evaluate the risk of water inrush in karst tunnels.Its innovation mainly includes that the value of evaluation index is an interval rather than a certain value;the single-index attribute evaluation model is improved non-linearly based on the idea of normal distribution;the synthetic attribute interval analysis method based on improved intuitionistic fuzzy theory is proposed.The TFN-AHP method is proposed to analyze the weight of evaluation index.By analyzing geological factors and engineering factors in tunnel zone,a multi-grade hierarchical index system for tunnel water inrush risk assessment is established.The proposed method is applied to ventilation incline of Xiakou tunnel,and its rationality and practicability is verified by comparison with field situation and evaluation results of other methods.In addition,the results evaluated by this method,which considers that water inrush is a complex non-linear system and the geological conditions have spatial variability,are more accurate and reliable.And it has good applicability in solving the problem of certain and uncertain problem.

Detection and treatment of water inflow in karst tunnel：A case study in Daba tunnel

In a karst tunnel, fissures or cracks that are filled with weathered materials are a type of potential water outlet as they are easily triggered and converted into groundwater outlets under the influence of high groundwater pressure. A terrible water inrush caused by potential water outlets can seriously hinder the project construction. Potential water outlets and water sources that surrounding the tunnel must be detected before water inflow can be treated. This paper provides a successful case of the detection and treatment of water inflow in a karst tunnel and proposes a potential water outlet detection(PWOD) method in which heavy rainfall(>50 mm/d) is considered a trigger for a potential water outlet. The Daba tunnel located in Hunan province, China, has been constructed in a karst stratum where the rock mass has been weathered intensely by the influence of two faults. Heavy rain triggered some potential water outlets, causing a serious water inrush. The PWOD method was applied in this project for the treatment of water inflow, and six potential water outlets in total were identified through three heavy rains. Meanwhile, a geophysical prospecting technique was also used to detect water sources. The connections between water outlets and water sources were identified with a 3-D graphic that included all of them. According to the distribution of water outlets and water sources, the detection area was divided into three sections and separately treated by curtain grouting.

富水裂隙围岩隧道涌水量计算方法与规律分析

富水裂隙区隧道涌水量预测精度较差,涌水问题尚未得到较好的解决。针对此问题,视裂隙围岩及注浆区为非均质各向异性介质,初期支护及二次支护结构为均质各向同性介质,构建了裂隙围岩下隧道涌水简化计算模型,基于地下水力学理论及流体质量守恒定律推导了富水裂隙区隧道涌水量计算公式。通过退化分析及案例工程现场实测数据验证了构建富水裂隙区隧道涌水简化计算模型的合理性及涌水量计算式求解的正确性,最后基于解析解揭示了各特征参数对富水裂隙区隧道涌水的影响规律,探讨了富水裂隙区隧道涌水机制。结果表明:理论计算值与现场实测值最大相对误差为8.1%,验证了构建模型的合理性及公式推导的正确性;隧道涌水量随裂隙最大宽度的增加而增大,受堵水结构的联合制约,两者近似呈线性关系;注浆区厚度与隧道半径比值在2倍以内时,隧道涌水量受注浆区厚度的影响显著;富水裂隙区隧道涌水受裂隙分布规律及支护结构的制约,应重视对裂隙分布的调查。

大采深高承压水条件下煤层底板突水问题及解决对策

在当前煤矿普遍面临大采深、底板高承压水、高地应力等采掘条件下,正确评价煤层底板承压水突水危险是做好防治水工作的基础。以河南省受底板灰岩承压水突水威胁的大水矿井为例,就底板破坏深度计算、突水系数计算及临界值、脆弱性指数法、不同水文地质单元的“双层水位”效应等问题进行了剖析。分析表明:在大采深和高地应力开采条件下,底板破坏深度较现有用经验公式计算得到的值偏大,一些矿井突水系数虽小于全国临界值,但回采过程中却发生了突水,脆弱性指数法有待于规范化。此外,井田范围内水文地质条件存在着时空变化,甚至会出现“双层水位”等现象。鉴于此,提出了建立大采深和高地应力开采条件下的底板破坏深度计算模型、确定矿区或矿井范围的临界突水系数值、规范脆弱性指数评价方法、查明水文地质条件的时空变化和不同单元的水动力参数、制定同各单元水文地质条件相适应的防治水措施等各项对策。

底板突水危险性评价研究进展

回顾了煤层底板突水危险性评价的发展历程,提出其危险性评价的体系:指标(指标体系的建立)—方法(评价方法的选取)—工具(处理工具的革新),并对3个环节进行总结。指出指标体系的发展不再是因素集的扩充,而是因素与因素之间非线性关系的处理以及对以开采条件及地质条件为两大基本要素集的化繁为简;将现有方法依据处理数据的逻辑分为3类:以数据的基础信息为基准,将原始数据对评价对象所产生的大小、高低、优劣性影响进行考量、排序及综合形成评价结果的第一类方法;对数据列进行人工评判、加工分析、拓展和延伸,挖掘数据的潜在信息,并形成最终评价结果的第2类方法;整理具有相同指标的数据集,通过数据信息处理技术发现数据间的共有信息,从而获得最终评价结果的第3类方法。指出未来评价方法的发展方向一方面是对突水系数法的传承,修正其在厚、巨厚、极薄隔水层的不良表现,另一方面是对机器学习新型方法的创新,对其本身及组合模型进行开发与应用。提出了处理工具所需实现的三大目标:矿井立体化模型的建立、评价结果的动态化演示、“定位、定量、定概率”三定指标的实现。分别探讨了三者面临的问题并阐述具体解决手段。在上述基础上,总体阐明了煤层底板突水危险性评价体系各环节的研究展望。

分区变权顶板突水危险性评价方法改进及实例

为准确合理地评价煤层顶板突水危险性,文章基于地理信息系统(geographic information system,GIS)空间分析技术,结合熵权法对突水分区变权模型进行改进优化。为避免权重确定的主观性与计算复杂性,引入信息熵求取常权向量。为防止“极大”或“极小”值权重超调过大,提高各主控因素综合控制作用与各分区值变权重均衡性,采用保守型分区变权函数对变权模型进行修正。通过直接对主控因素栅格图运算和处理,避免因钻孔插值所造成的构造信息丢失问题。将改进模型与常权模型及仅通过钻孔构建的风险型分区变权模型进行比较,以实际突水点对评价模型进行识别检验。结果表明,改进的分区变权模型评价效果更好、精度更高,对煤矿顶板水害预测与防治具有指导性作用,在口孜东矿取得良好的应用效果。

穿越复杂岩溶环境的特长隧洞涌突水危险性评价——以滇中引水工程小扑隧洞为例

在复杂岩溶区,涌突水危险性评价是保障隧洞施工安全的重要工作内容之一。以滇中引水工程玉溪红河段小扑隧洞为例,在分析隧洞地质与水文地质条件的基础上,综合考虑岩石的可溶性、地质构造因素、地表汇水条件、地下水化学特征、隧洞埋深与地下水位的关系5个控制性因素,采用岩溶隧洞涌突水危险性评价系统对隧洞的涌突水危险性进行了预测与验证。结果表明:小扑隧洞北段位于鲁纳寺—牛恋村岩溶子系统的径流区。在丰水期,隧洞岩溶涌突水中危险区、高危险区、极高危险区的长度占比分别为15.8%,55.4%,28.8%。小扑隧洞南段位于西河和祭天山—黄营岩溶子系统的补给、径流区。在丰水期,隧洞涌突水中危险区、高危险区、极高危险区的长度占比分别为7.4%,52.7%,39.9%。施工阶段,小扑隧洞北段主洞揭露暗河管道,发生涌突水事故,2#支洞发生突水涌沙事故,与对应的涌突水高-极高危险性结果吻合。涌突水危险性评价结果有效地支撑了隧洞的涌突水灾害防治与安全施工。

自适应接地电阻的本安型电法监测场源信号发射装置设计

电法监测技术因其对煤岩电阻率变化的高灵敏特点而逐步在突水风险较高的矿井进行推广应用,然而由于井下工作面两巷工况环境复杂,不同场源发射监测电极间的接地条件差异较大且随时间变化,难以在整个监测周期内提供稳定的场源信号。设计了一种基于STM32F407的负反馈式本安型电法监测场源信号发射装置,该装置可自适应调节不同发射电极间的接入电阻,具备双重可靠本安保护电路,实现了本安限制条件下场源信号的最大功率稳定发射,既而使场源能量最大化加载至目标监测地质体来获得尽可能强的场源响应信号,提升电法监测系统数据采集质量,提高反演解释的准确性。

综放开采下组煤首采面上覆老空水探查及突水危险性评价

为了探究左权五里堠煤业上组煤老空区富水性及其对下组煤首采工作面突水的危险性,以下组煤首采面为研究背景,系统分析了研究区上下2组煤层顶底板岩性组合及水文地质条件;根据物探探测结果,在下组煤首采面巷道先后施工了20个探放上组煤老空水钻孔,发现上组煤老空水存在局部水量大、水压高、富水性分布不均的特点。在此基础上,建立了上下组煤层开采顶底板的工程地质数值模型,采用数值模拟方法对上组煤和上下组煤开采完毕后的应力场及塑性区场变化特征进行了对比分析,得到上组煤层开采后底板破坏深度为11 m,下组煤开采后导水裂隙带高度为112 m,没有波及上组煤底板破坏深度范围,与首采面实测涌水量反映的规律是一致的。根据首采面及附近2个钻孔的资料,采用2种相关经验公式类比计算了下组煤开采导水裂隙带高度,优选了可靠性较高的经验公式。

基于LDA-RBF及综合赋权法的顶板突水危险性评价

为了解决龙凤煤矿9号煤层开采过程中顶板突水危险性问题,采用线性判别分析法(LDA)构建1种LDA-RBF神经网络导水裂隙带发育高度预测模型,并基于改进CRITIC评价法结合层次分析法(AHP)建立了CRITIC-AHP综合赋权法,分别评价矿区顶板采裂危险性及含水层富水性等级;通过ArcGis地理信息处理技术,将采裂危险性分区与富水性分区叠加,得到9号煤层顶板突水危险性综合分区图。结果表明:LDA-RBF神经网络预测模型结构简单且拟合精度更高,9号煤层导水裂隙带发育预测高度为50.4 m,已超过区域内大部分含水层底界标高,表明大部分区域存在较高的采裂危险性;而改进后的综合赋权法避免了评价结果主客观性过强的问题,其富水性分区结果与钻孔实际涌水量相符;突水危险区主要在矿区中北部呈条状分布,这是该区域含水层富水性较强和采裂危险性较高共同作用的结果,因此,在实际开采中应对以上区域予以重视。

基于博弈论组合赋权-灰关联投影法的山岭隧道突涌水风险评价

为有效减少隧道突涌水灾害带来的后果损失,提出一种基于序关系分析法(order relation analysis method,G1)-指标相关性权重确定方法(criteria importance through intercriteria correlation,CRITIC)和灰关联矢量投影原理的隧道突涌水灾害的风险评价方法。在调研相关文献和工程实例的基础上,考虑了地层岩性、水文地质、不良地质和施工设计4个方面,构建出一个可量化的隧道突涌水风险评估指标体系;其次,为更好地避免人为因素带来的偏差,采用G1-CRITIC进行主客观赋权,通过引入博弈论得到主客观赋权的组合权重,实现对各评价指标权重的科学合理分配;最后,结合灰关联矢量投影法对隧道涌水风险等级进行定量评价。将该风险评价方法应用于文笔山1#隧道3个洞段样本,对其进行隧道突涌水风险评估,实例结果表明,隧道样本3突涌水风险等级为Ⅳ级,另两个隧道洞段样本为Ⅱ级涌水风险,得出的风险评价等级与实际开挖情况吻合,此模型可对多因素影响下的工程地质灾害进行准确评价,与其他模型结果对比更加验证了该评价模型的可行性与准确性。

王家寨隧道第三系半成岩富水段涌水突泥机制及风险评估

为探究隧道穿越第三系半成岩富水段时引发的涌水突泥、冒顶等地质灾害机制,依托云南临清高速公路王家寨隧道,通过室内力学试验和模糊层次分析法,对第三系半成岩力学特性、作用机制及涌水突泥灾害风险进行分析。研究表明:1)王家寨隧道第三系半成岩遇水软化特性明显,随着含水率增加其黏聚力先增后减,内摩擦角不断减小,含水率为18%时黏聚力与内摩擦角分别为12.53 k Pa和7.35°,围岩逐渐失稳。2)软弱的第三系半成岩、高地下水量及隧道开挖扰动为王家寨隧道第三系半成岩富水段发生涌水突泥灾害的主要影响因素。3)王家寨隧道第三系半成岩段可按工程地质条件、水文地质条件划分为A、B、C、D 4段,各段涌水突泥灾害风险由大到小排序为B段=C段>A段>D段,其中评估的A段涌泥量与实际涌泥量较为吻合。

基于AHP与GIS的煤层顶板突水危险性评价

为准确评价赵家寨矿12采区东翼二_(1)煤层顶板突水问题,选取导水裂隙带高度、导水裂隙带高度范围内的含水层厚度、新近系含水层的富水性、剩余黏土层厚度、断层分维值5个因素作为煤层顶板突水的主控因素,运用层次分析法确定各主控因素对总目标的影响权重,并通过自然分级法确定研究区的分区阈值,最终获得了研究区二_(1)煤层顶板突水危险性评价模型。评价结果与后期工作面开采的疏水结果相一致,实际疏放水量与预测静水储量吻合度达96.7%,实现了二_(1)煤层的安全回采。

基于多种解析法和数值法求解巨厚砂岩水文地质参数

在煤矿开采过程中,矿井涌(突)水等事故不仅会造成巨大的经济损失,还严重威胁工作人员的生命安全。水文地质参数在计算矿井涌水量过程中扮演着重要角色,因此,准确测定含水层的水文地质参数对于煤矿防治水等工作具有重要意义。为了获取更加贴近实际的矿区顶板巨厚洛河组砂岩含水层的水文地质参数,以新庄煤矿洛河组巨厚砂岩含水层上、下段的抽水试验资料为依托,采用传统的非稳定流的Theis公式法、Jacob直线图解法和水位恢复法等解析法,结合实际场地特征,计算出洛河组砂岩含水层上、下段的渗透系数分别为0.22~0.59和0.03~0.35 m/d;上段导水系数为128.74~373.67 m^(2)/d,下段为5.52~47.07 m^(2)/d;上段的贮水系数为2.22×10^(-4)~6.69×10^(-3),下段为6.53×10^(-5)~3.29×10^(-3)。并通过FEFLOW软件建立新庄矿区的地下水流数值模型,求解洛河组含水层的水文地质参数,得到洛河组上、下段渗透系数分别为0.55和0.45 m/d。通过多种方法对比分析表明,通过数值模拟法得到的水文地质参数结果与多种解析法计算的结果相近。在此基础上,根据各方法得出的水文地质参数计算矿井涌水量,并与实际涌水量进行对比,结果表明:在含水层上段,采用数值模拟法得到的水文地质参数计算的涌水量更加接近实际涌水量;而在洛河组下段,采用Jac-ob直线图解法得到的水文地质参数计算的涌水量更加接近实际涌水量。进一步提高了水文地质参数计算的准确度,为后期的含水层富水性研究、矿井涌水量预测以及类似矿区顶板巨厚洛河组砂岩含水层的矿井水防治工作提供依据。

基于FAHP-EWM组合权重的突水危险性评价研究

通过统计分析吴堡矿区某井田先期开采地段地质及水文地质资料,确定影响主采煤层底板突水的主控因素,采用模糊层次分析法(FAHP)和熵权法(EWM)计算各因素的主客观权重,并利用加法合成法、极差最大化法、博弈论法和最小鉴别信息法分别计算组合权重;结合脆弱性指数法,利用GIS的信息融合技术得到研究区的突水脆弱性评价分区,4种评价结果的分区过渡趋势基本一致,但存在部分区域其评级结果不同。采用Spearman等级相关系数对4种突水脆弱性评价结果进行优选,结果表明:基于最小鉴别信息法得到的脆弱性指数等级排序与“合理排序”的相关系数最高;在这4种脆弱性评价结果中,采用最小鉴别信息法组合赋权得到的突水脆弱性评价效果最好。

复杂地质条件下岩溶台地隧道灾变风险评估:以安平隧道为例

复式向斜岩溶台地地质条件复杂,隧道穿越时,多发生突水涌泥等地质灾害。以安平隧道为例,在隧道线路设计初期,从地质角度出发,分析隧道线路范围内存在的5个主要地质问题及可能发生的地质灾变风险,并逐一对其进行评估和评价;采用宜避不宜扰的地质选线理念,根据评价结果选择路线绕避方案和确定平纵设计指标。研究成果对类似复杂地质条件下的岩溶台地隧道地质选线和路线设计具有一定的借鉴意义。

麻家梁矿带压开采安全评价

为评价麻家梁矿煤层受奥陶系岩溶水的影响程度,结合充水含水层充水条件、充水途径,在分析该矿地质和水文地质条件的基础上,介绍了煤层底板含隔水层特征,对底板扰动破坏深度、有效隔水层厚度及可能导水通道进行分析,采用标高比对法、突水系数法、斯氏公式法3种不同方法对主采煤层带压开采情况进行突水危险性评价,对开采煤层底板带压开采安全性进行综合评价,对煤层进行合理分区,提出了奥灰突水判识方法,为矿井防治水工作提供技术指导,确保矿井安全生产。