Overburden fracture evolution laws and water-controlling technologies in mining very thick coal seam under water-rich roof

Considering the danger of water inrush in mining very thick coal seam under water-rich roof in Majialiang Coal Mine,the universal discrete element(UDEC)software was used to simulate the overburden fracture evolution laws when mining 4#coal seam.Besides,this study researched on the influence of face advancing length,speed and mining height on the height of the water flowing fractured zones(HWFFZ),and analyzed the correlation of face advancing length and change rules of aquifer water levels and goaf water inflow.Based on those mentioned above,this research proposed the following water-controlling technologies:draining the roof water before mining,draining goaf water,reasonable advancing speed and mining thickness.These water-controlling technologies were successfully used in the feld,thus ensured safely mining the very thick coal seam under water-rich roof.

Seepage field distribution and water inflow laws of tunnels in water-rich regions

Currently,the water inrush hazards during tunnel construction,the water leakage during tunnel operation,and the accompanying disturbances to the ecological environment have become the main problems that affect the structural safety of tunnels in water-rich regions.In this paper,a tunnel seepage model testing system was used to conduct experiments of the grouting circle and primary support with different permeability coefficients.The influences of the supporting structures on the water inflow laws and the distribution of the water pressure in the tunnel were analyzed.With the decrease in the permeability coefficient of the grouting circle or the primary support,the inflow rate of water into the tunnel showed a non-linear decreasing trend.In comparison,the water inflow reduction effect of grouting circle was much better than that of primary support.With the increase of the permeability coefficient of the grouting ring,the water pressure behind the primary lining increases gradually,while the water pressure behind the grouting ring decreases.Thus,the grouting of surrounding rock during the construction of water-rich tunnel can effectively weaken the hydraulic connection,reduce the influence range of seepage,and significantly reduce the decline of groundwater.Meanwhile,the seepage tests at different hydrostatic heads and hydrodynamic heads during tunnel operation period were also conducted.As the hydrostatic head decreased,the water pressure at each characteristic point decreased approximately linearly,and the water inflow rate also had a gradual downward trend.Under the action of hydrodynamic head,the water pressure had an obvious lagging effect,which was not conducive to the stability of the supporting structures,and it could be mitigated by actively regulating the drainage rate.Compared with the hydrostatic head,the hydrodynamic head could change the real-time rate of water inflow to the tunnel and broke the dynamic balance between the water pressure and water inflow rate,thereby affecting the stress state on the supporting structures.

Application of 3-D Parallel Electrical Technology Detecting the Water-Rich Areas

Coal working face is damaged more and more seriously by water below the coal face floor. Therefore, floor water detection is a must in the process of extraction. This article aims to introducing application and principle of the two-gateways parallel 3-D electrical technology and the arrangement of the observation system. The authors use this method to detect the water under the floor of a mine in north of Anhui. The results show that the two-gateways parallel 3-D electrical technology can accurately locate the water-rich areas, providing the basis for drilling drainage and grouting construction.

Water shutoff model test in water-rich sandy stratum by phosphoric acid-water glass grout

The rheological behavior of phosphoric acid-water glass grout in different mixing ratios was studied. Grout made of water glass with Baume degree of 20° and 13.4% phosphoric acid by 1:1 volume ratio is found to be more effective in stopping water. Laboratory model test of water shutoff by grouting was conducted. Test results show that the diffusion length and water cutoff effect of the grout are significantly improved as the grout head is raised, due to the dilution of underground water, and it takes the grout longer than its gel time to cut off water.

Numerical research on stability control of roofs of water-rich roadway

In order to study the strength-weakening law of roofs of water-rich roadway, this study used FLAC software, and simulated and analyzed the failure characteristics of the surrounding rock of water-rich roadway under the condition of different cross sections and support parameters, finally obtained the stress distribution of the principle stress of the roadway as well as the displacement variation of its surrounding rock. Results indicate that the roof stability of roadway with semicircular cross section is better than the roadway with inclined rectangular cross section under water-rich condition. Besides, the surrounding rock deformation of roadway under the action of water shows a pronounced increase compared to the roadway without the action of water due to the fact that water will obviously weaken the surrounding rock of roadway, especially its roof. It is very beneficial to control roof stability of water-rich roadway and guarantee the roadway stability during its service life by improving the pretension of bolt and cable as well as decreasing inter-row spacing of the bolt.

Stability analysis and grouting treatment of inclined shaft lining structure in water-rich strata: A case study

The stability of inclined shaft lining structure (ISLS) in complex water-rich strata is affected by many factors, suchas water pressure, joint, soft rock, lining corrosion and so on. The instability of the ISLS will affect the safe andefficient coal mine production. Bathe sed on the geological conditions of the Xiaobaodang coal mine, this papertested the evolution characteristics of concrete composition in long-term water seepage areas and revealed theinfluence mechanism of corrosion weakening of shaft lining (SL) in water-rich strata. Meanwhile, transientelectromagnetic, ground penetrating radar, and infrared monitoring are used to detect the water-rich zones, anddamage zones of surrounding rock and lining water seepage zones, and a three-level safety evaluation model forthe instability risk of ISLS is constructed. Water abundance of the surrounding rock, surrounding rock deterioration, and shaft lining seepage were the specific indicators in the model. The main inclined shaft (MIS) in thestudied coal mine is divided into three levels: non instability risk zone, potential instability risk zone, and highinstability risk zone. According to the evaluation results, comprehensive prevention and control measures of“hydrophobic hole drainage” and “back-lining grouting” are adopted for the water inrush source and the surrounding rock micro-crack water channel. The precise prevention and control of ISLS is realized. The researchresults also provide a reference for the stability evaluation of ISLS and the accurate prevention and control undersimilar conditions.

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。

基于水平旋喷桩处置优化的地铁隧道施工变形控制分析

为研究富水砂层隧道中水平旋喷桩+超前小导管组合预加固的效果,以青岛地铁某区间段隧道为依托,采用有限元数值模拟方法,对比分析了无预加固、单独使用水平旋喷桩及旋喷桩配合超前小导管组合预加固三种工况的加固效果。结果表明,与无预加固方案相比,单独使用水平旋喷桩预加固可使地表沉降、拱顶沉降、掌子面纵向位移分别相应减少约61%、59%、38%;而水平旋喷桩与超前小导管组合预加固方案可使地表沉降、拱顶沉降、掌子面纵向位移分别相应减少约66%、77.6%、38.9%,典型开挖断面处与拱脚处地下水渗流量分别减少93.4%、96.7%,预加固效果与止水效果显著。

富水砂层地铁盾构隧道渣土混合改良的流塑性与渗透性

[目的]盾构在富水砂层中掘进时,易产生刀盘扭矩过高、磨损严重以及螺旋运输机喷涌等问题。为了保证施工的安全性,需对渣土进行改良。[方法]以西安地铁16号线某盾构区间工程为依托,根据砂土地层自稳性差、摩擦性高、渗透率高的特点选取渣土改良剂。通过渣土坍落度试验、渗透试验、现场试验相结合的方式,采用泡沫单独改良、泡沫及膨润土泥浆混合改良两种方案开展富水砂层渣土改良试验研究。[结果及结论]实际盾构掘进施工中,在考虑安全、高效、经济的前提下,结合室内试验所得数据,确定采用膨润土泥浆、泡沫混合改良的方案。当膨润土与水质量比为1/8,发泡液质量分数为3%时,改良剂性能满足施工要求;泡沫单独改良渣土受含水率影响大,含水率越高,泡沫最佳注入率越小。中砂的最佳改良方案是BIR(膨润土泥浆注入比)为10%,FIR(泡沫注入率)为20%~25%;砾砂的最佳改良方案是BIR为10%,FIR为35%~40%。工程实践表明,渣土混合改良效果良好,盾构掘进参数平稳。

富水砂层中盾构始发穿越既有地铁线路的结构稳定性研究

[目的]富水砂层地质条件下,新建地铁线路盾构始发穿越既有地铁线路时,对既有地铁线路结构稳定性的研究较为鲜见,需总结类似工程的相关规律。[方法]以新建的郑州地铁7号线黄河迎宾馆站—英才街站区间盾构始发穿越既有地铁2号线结构工程为依托,根据实际工况采用有限元软件MIDAS GTS NX建立了施工区间的三维数值模型,并利用软件的结果提取功能得到了该工程对应模型的模拟结果。选取现场2个监测点位,将2个测点的现场实测值与模拟计算值进行对比,证实了该模型的准确性。在此基础上,进一步研究了盾构始发穿越、一般下穿施工两种穿越方式下对既有地铁线路结构稳定性的影响,以及始发洞门与既有地铁结构间竖向距离d的4个取值对既有地铁线路结构稳定性的影响。[结果及结论]所建三维模型在一定程度上可反映实际工况。在既有地铁线路结构、材料、加固方式等因素均不变的情况下,既有地铁线路结构的稳定性因穿越方式的不同而有所差异,与一般下穿施工相比,采用盾构始发下穿方式时对既有地铁线路结构的影响较小。采用盾构始发下穿方式时,d的取值不同,对既有地铁线路结构稳定性的影响有较大差异。d=2.00 m对既有地铁线路结构的影响较小,工程成本也较小。建议在工程条件允许下采用盾构始发下穿方式,且推荐d值取2.00 m。

长江流域建立水资源刚性约束制度的关键问题与对策研究

南方丰水地区建立水资源刚性约束制度,是为了更好地促进生态环境高水平保护和经济社会高质量发展。基于长江流域水资源开发利用、管理现状及特点,分析了长江流域建立水资源刚性约束制度需重点研究的关键问题,并从水资源和水环境承载能力、用水定额标准、计量监测、水资源规划论证、监管考核和市场机制等方面,提出长江流域建立水资源刚性约束制度的对策建议。

基于DNN的煤矿富水区探测反演方法研究

提出了一种基于DNN的煤矿富水区探测反演算法,该算法可以快速准确地实现煤矿富水区二维分布模型的重建。首先,利用时域有限差分方法(FDTD)获得不同分布模型的数值解;随后,依据数据样本搭建网络框架,网络的输入主要为电场分量,输出为相应的模型电导率参数。通过对神经网络进行训练,得到网络的最优系数,随后对富水区分布进行反演预测;结果表明:DNN算法在单个小目标异常体反演中,可以有效克服BP神经网络模型失效的问题,且对于多目标异常体的反演效果更加准确。另外,相同数据集下,DNN的训练耗时与预测耗时也少于BP神经网络。实验结果表明,该算法可以有效提高煤矿富水区探测效率。

富水岩溶地区隧道涌水预测与施工处置技术研究

针对贵州某隧道施工过程中遭遇一处连通地下暗河的大型溶洞引起隧道内大规模涌水的灾害进行研究,结合水文地质情况对涌水量进行预测和分析后,现场先对岩溶水进行初步释压,后采用水泥砂浆分步回填隧道上伏溶腔以封堵岩溶出水口;进一步采用集水管引排岩溶水的方式对剩余地下水进行二次加强处理,同时将集水管与隧道外侧的泄水洞相连,二者构成一套完整的引排水系统的处治手段。采用堵排相结合的原则有效地达到涌水处置目的,确保了隧道的安全施工,可为类似地层的隧道施工提供有益的借鉴。

山西省五台县发现天然矿泉水开发潜力区

利用调查、取样、化验、物探和钻探等方法手段,对山西五台地区的水文地质条件和地下水质现状进行了研究,发现该地区水质状态良好,部分区域锌(Zn)、锶(Sr)含量达到矿泉水标准,Zn最大值2.3 mg/L、Sr最大值1.17 mg/L,富Zn面积73.71 km^(2),富含Sr面积134.25 km^(2),实施探采结合井最终钻获高品质的水资源,在五台县实现了天然矿泉水潜力区的新突破,有力支撑了地方的健康饮水工程.

大定源回线装置瞬变电磁法在煤矿采空区探测中的应用

该文通过研究大定源回线装置瞬变电磁法在煤矿采空区探测中的应用,旨在提高煤矿采空区探测的效率和准确性。深入探讨大定源回线装置瞬变电磁法的原理和工作机制。在此基础上,设计并实施适用于煤矿采空区的探测方案,并通过试验进行验证。结果表明,大定源回线装置瞬变电磁法在煤矿采空区探测中取得显著的效果。大定源回线装置瞬变电磁法具有高效、准确、可靠的特点,能够快速识别采空区位置,为后续生产建设提供保障,同时也为其他煤矿采空区勘察提供参考。

富水砂层深基坑施工诱发邻近建筑物变形研究

依托南通市环西文化广场站项目,在围护结构施工阶段、基坑降水阶段、基坑开挖阶段采取一系列措施,减少深基坑施工对周边重要建(构)筑物的影响,项目影响电视塔的工程全部施工完成后,电视塔倾斜和沉降均在规范允许范围内。

南京地铁7号线中胜站密贴下穿运营站MJS+水平冻结施工与实测研究

为解决南京新建地铁7号线在承压富水砂层近贴下穿既有10号线中胜站开挖时易发生涌砂涌水现象及冻结对既有线变形的影响问题,提出一种全方位高压喷射工法(metro jet system,MJS)+水平冻结法联合加固承压富水砂性地层的施工方法。根据实际工程,确定MJS+水平冻结加固工艺、加固参数、加固范围及冻结的方案,并通过数值模拟方法预测冻结温度场的变化规律、计算开始冻结的合理时间和积极冻结时间。对冻结过程中的土体温度、冻结及开挖过程中的既有车站底板位移进行监测,并在此基础上对暗挖方案进行优化。工程实践表明:1)冻结过程中中部MJS加固体温度一直高于端部MJS加固体温度,应当加强对中部位置温度的监测;2)冻土帷幕范围应控制在MJS加固体范围内,否则土体冻结会对冻胀变形影响较大,为此提出了上部钻孔取土泄压及间歇冻结的方案,可在一定程度上减小冻胀;3)本工程冻结及开挖阶段既有车站结构变形较小,减小了对近贴既有车站结构的影响;4)优化后的暗挖方案可加快施工进度,原开挖时间约80 d,优化后开挖时间缩短至66 d。

基于P-IBI指数的修河中下游水生态健康评价

修河流域为鄱阳湖流域五大支流之一,为掌握该流域水生态健康现状,该研究以2021年丰水期(8月)和枯水期(12月)14个样点的浮游植物类群和水体理化指标调查数据为基础,构建了浮游植物生物完整性指数(P-IBI)评价体系,系统评价了修河中下游水生态健康状况。调查结果表明,修河中下游共记录到浮游植物6门44属66种,其中丰水期、枯水期分别发现优势种17和5种;经分布范围检验、判别能力分析以及矩阵Pearson相关性分析筛选出6个核心评价指标,即硅藻属百分比、硅藻门细胞密度百分比、绿藻门细胞密度百分比、Shannon-Wiener指数、绿藻门细胞生物量以及硅藻门细胞生物量百分比;通过比值法统一量纲赋分并划分出4个健康评价等级,结果显示修河中下游水域整体处于“亚健康”,其中处于“健康”、“亚健康”、“一般”和“差”的点位占比分别为28.57%、21.43%、21.43%和28.57%;冗余分析表明,修河中下游水生态健康的主要环境驱动因子为透明度、水温和溶解氧。该研究可为鄱阳湖子流域水生态健康管理和水生态修复提供参考与科学依据。

侧部承压溶洞与深埋隧道间隔水岩体安全厚度研究

为保证深埋隧道安全通过侧部高压富水溶洞区段,在隧道突水发生机制分析与隔水岩体最小安全厚度划分的基础上,结合突变理论、鲁宾涅特方程及相关工程经验对隧道边墙岩体安全厚度进行研究,导出最小安全厚度计算公式,建立突水判据,分析相关影响因素对隧道边墙隔水岩体最小安全厚度的影响规律。结果表明:隔水岩体最小安全厚度H_(min)与围岩力学参数弹性模量E、内摩擦角φ呈正相关,与溶洞水压力q_(w)、岩梁跨度L及隧道埋深h呈负相关;各因素对H_(min)影响程度由大到小依次为h、φ、E、L与q_(w),其中h与φ影响程度相近,E在超过3 GPa的情况下H_(min)变化趋于平缓,E的影响程度与L相近;结合有限元模拟结果和工程实例分析,验证了H_(min)理论计算公式及突水判据的准确性与可行性,对相关工程建设具有指导意义。

电解水作为饮用水在畜禽生产中的应用研究进展

饮用水是畜禽水分的主要来源,干净、充足的饮水是畜禽健康的重要保证之一。电解水具有抗菌性、无残留、无污染、价格低等特点,并具有一定的药理作用,在食品加工、医用消毒及畜禽栏舍消毒等方面有广泛应用。近来,可饮用电解水代替普通地下水作为畜禽饮用水成为研究的新焦点。本文综述了目前常用饮用类电解水的种类及其在畜禽生产中的主要应用,为电解水在畜禽生产中的安全应用提供参考。