Influence of confined water on the limit support pressure of tunnel face in weakly water-rich strata

In the process of shield tunneling through soft soil layers,the presence of confined water ahead poses a significant threat to the stability of the tunnel face.Therefore,it is crucial to consider the impact of confined water on the limit support pressure of the tunnel face.This study employed the finite element method(FEM)to analyze the limit support pressure of shield tunnel face instability within a pressurized water-containing layer.Subsequently,a multiple linear regression approach was applied to derive a concise solution formula for the limit support pressure,incorporating various influencing factors.The analysis yields the following conclusions:1)The influence of confined water on the instability mode of the tunnel face in soft soil layers makes the displacement response of the strata not significant when the face is unstable;2)The limit support pressure increases approximately linearly with the pressure head,shield tunnel diameter,and tunnel burial depth.And inversely proportional to the thickness of the impermeable layer,soil cohesion and internal friction angle;3)Through an engineering case study analysis,the results align well with those obtained from traditional theoretical methods,thereby validating the rationality of the equations proposed in this paper.Furthermore,the proposed equations overcome the limitation of traditional theoretical approaches considering the influence of changes in impermeable layer thickness.It can accurately depict the dynamic variation in the required limit support pressure to maintain the stability of the tunnel face during shield tunneling,thus better reflecting engineering reality.

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.

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.

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.

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.

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.

基于深度学习的轻量化炮孔智能检测方法

在隧道(巷道)钻爆法施工过程中,智能装药可以取代人工作业,减少装药作业中危险事故的发生。然而,隧道中光线条件差、炮孔目标小和掌子面裂隙等因素会造成智能装药时炮孔的错检和漏检,同时车载计算机有限的算力也是制约炮孔识别大模型使用的难点。MCIW-2深度学习模型,可以解决在隧道掘进作业环境中的高精度炮孔检测和实时性部署问题。模型根据采集到的炮孔图像尺寸特征采取自适应锚框聚类算法优化检测框的长宽比尺寸参数;采用了具有动态非单调聚焦机制的损失函数WIoU(Wise Intersection over Union),通过优化边框回归的损失应对低质量炮孔图片的挑战实现了高精度检测;采用了MobileNetv3-Small网络与CBAM(Convolutional Block Attention Module)注意力机制构建了主干网络结构,减少了模型参数保证了检测准确率,满足车载设备的轻量化部署需求。经实验证明,MCIW-2模型在炮孔识别精确率方面达到了96.18%,检测速度达到了59 fps。与基准YOLO(You Only Look Once)系列目标检测模型文件最小的模型相比,所构建的轻量化炮孔智能检测模型减小了75.86%,模型文件仅为2.80 Mb,优于YOLO系列的基准目标检测模型。使用MCIW-2深度学习模型对工作面现场视频进行测试,实现了快速、精确地检测炮孔,测试结果表明,该模型适用于智能装药工程的轻量化部署需求,具有良好的适应性,在综合性能方面具有显著优势。

智能炮孔检测与路径规划系统设计与应用

钻爆法巷道掘进的装药作业是巷道掘进的一个重要工序环节,传统的装药过程机械化程度较低,依赖人工操作,导致耗时费力且安全性较差。为了解决巷道掘进过程中钻爆法装药存在的问题,基于深度学习与智能算法技术,创新性地提出了智能化改进方案——智能炮孔检测与路径规划系统。该系统可以提高装药精度和施工效率,为钻爆法的智能化装药提供技术支持。系统架构为数据访问层、业务逻辑层和表示层,包括图像采集、数据处理、炮孔检测、路径规划和可视化界面等模块。首先,通过高精度图像传感器获取掘进工作面上的炮孔图像数据;其次,采用基于深度学习的炮孔智能检测模型进行数据处理和分析,实现对炮孔数据的准确检测和识别;最后,将改进贪心算法与2-opt局部搜索算法相结合,设计装药路径规划算法,实现了对装药顺序的高效规划和优化。系统集成了可视化功能,提供了直观的炮孔数据管理、智能炮孔识别、炮孔数据存档和装药路径规划等操作,方便施工人员进行实时监控和动态调整。研究结果表明,该系统在炮孔检测方面的准确率可达96.24%,路径规划算法的平均计算耗时为100 ms左右,该系统可提高钻爆法施工过程中装药的效率、安全性和智能化水平,服务于钻爆法巷道掘进智能化装药过程中的炮孔检测与路径规划。

24110工作面强制放顶安全管理

为减小24110综采工作面初次来压时顶板大面积垮落而形成的飓风,避免造成工作面设备和施工人员受伤,采用深孔预裂爆破技术强制放顶,根据煤层顶板破拆原理,并结合4上号煤层顶板实际情况,58个炮眼分别设计在工采面两条顺槽内,以保证工采面初压时的安全生产。

隧道炮孔高精度定位及水封抑尘控制爆破施工工艺研究

文章以深圳外环高速公路东莞段工程第一施工合同段龙眼山隧道为工程背景,展开技术研究,总结、提炼了一套隧道炮孔高精度定位及水封抑尘控制爆破施工技术。在前期钻孔阶段,基于红外投影技术,采用红外投影设备将压缩成胶片的炮孔布设图直接投影至隧道掌子面上,再由工人进行油漆打点,钻孔工人根据油漆点位置进行精准钻孔施工。在隧道爆破阶段,将常规水压爆破施工技术进行改进,在传统封堵水袋中加入水溶性黏尘剂,显著增加了爆破后水雾的黏尘效果。在炮筒封堵中综合运用树脂类快凝封堵剂,显著减少了爆破能量的损失,同时强化其爆破效果,降低材料损耗。

大断面一次成巷爆破数值模拟及试验研究

为有效解决大断面掘进爆破作业中存在的技术难题,在大断面巷道中采用孔间多时序一次成巷爆破技术。利用LS-DYNA有限元数值模拟软件,通过改变大断面巷道炮孔掏槽方式、孔间起爆时差,进行数值模拟计算。在此基础上确定了掏槽方式、炮孔布置方式等关键爆破技术参数,并进行了现场试验及应用。结果表明:与分步开挖相比,采用孔间多时序全断面一次掘进成巷爆破技术后,巷道成型效果好、炮孔利用率提高18%。改进后的爆破方案有效地解决了大断面分步开挖中面临的问题,对地下矿大断面掘进爆破巷道成型及控制具有一定的参考价值。

钻孔爆破炮孔孔壁压力计算模型

针对钻孔爆破数值模拟过程中炮孔孔壁压力取值较为复杂的问题,通过分析炸药爆轰过程以及爆破介质的破坏和运动过程,构建了孔壁压力的简化计算模型。该模型将爆破过程分为4个阶段:炸药爆轰炮孔升压、炮孔初步弹性膨胀、孔壁裂纹张开且气体流入、介质剥离抛掷且气体逸出。通过简化分析介质的爆破破坏过程,分别确定了各阶段的持续时间。通过简化分析爆炸气体体积的变化,并基于理想气体状态方程,分别确定了各阶段孔壁压力随时间变化的数学函数。通过现场实验结果对计算模型进行了验证,计算结果与实验结果吻合情况良好。该计算模型考虑了多种因素对爆破过程的影响,又未引入难以确定的系数,方便实际应用,可用于理论分析或数值模拟中爆破荷载的取值。

控制爆破技术在场地平整施工中的应用

采用深孔和浅孔控制爆破技术对复杂环境下石方进行爆破开挖。根据爆破区域环境和工程特点,采用萨道夫斯基公式计算被保护民房所能允许的最大单段起爆药量,作为台阶高度和孔网参数设计的主要参考依据。同时对爆破振动进行现场监测,根据测试结果,对台阶高度、孔网参数和起爆规模进行调整,从而使爆破振动效应满足各被保护建筑物的要求,使爆破施工安全高效的进行。

不同炮孔间距对岩石爆炸裂纹扩展影响的数值分析

为实现对岩石的充分破碎,有效利用炸药能量,基于有限元分析软件 ANSYS/LS-DYNA及流固耦合(ALE)算法,研究了不同炮孔间距对岩石(角岩)爆炸裂纹扩展的影响,同时将模拟结果应用在工程实践上加以验证。结果表明:随着两炮孔间距离的增大,单炮孔周围裂纹扩展更加充分,炮孔周围粉碎区增大,萌生的分支小裂纹逐渐减少,主裂纹增多。在两炮孔之间受到相邻炮孔爆炸应力波影响的区域,主裂纹发育扩展较为明显,且随着炮孔间距的增大,主裂纹相互贯通的位置越靠近两炮孔中心连线方向。工程实践表明:数值模拟结果与爆破工程效果具有较好的吻合性,将数值模拟结果用来指导爆破方案设计是可行的,能够为爆破工程提供重要的参考。

平行束孔爆破模型试验及其机理探讨

本文介绍了垂直密集束状平行炮孔(简称平行束孔)落矿有底柱崩落采矿法的实质和结构,并分析了它的特点和优点。由于平行束孔落矿是核心的关键技术,本文为此做了爆破模型试验,对其爆破机理进行了研究和探讨。该项研究在国内尚属首次。

岩巷切缝药包楔形掏槽爆破模型试验与分析

为了研究合理的掏槽方式改善岩巷掏槽效果差、炮眼利用率低的问题,采用水泥砂浆模型对切缝药包楔形掏槽爆破进行了试验研究。共设计了4组对比试验,每组试验分别在6组不同强度的水泥砂浆模型上展开,模型炮孔数目均为6个,每个炮孔装一发8号电雷管起爆。试验结果表明,切缝药包装药结构提高了炮孔利用率、增大了槽腔体积及降低了掏槽碎块的大块率;并得到了不同强度模型最优的掏槽方式,其中80°切缝药包楔形掏槽爆破在不同强度模型下炮孔利用率、槽腔体积及掏槽碎块大块率均相差较小,用于岩性变化较大的岩巷中,可得到较好的掏槽效果。切缝药包楔形掏槽爆破利用切缝对能量的导向作用,实现裂纹的定向扩展,并提高了掏槽效果。

大直径束孔高分段空场嗣后充填采矿法在西藏甲玛矿的应用研究

近年来,高原采矿活动日渐频繁。为实现西藏地区环境保护与工业经济协调发展的理念,针对甲玛矿高寒、缺氧的开采技术环境,研发机械化程度高、生产能力大的采矿方法非常有必要。基于此,综合比较推荐采用大直径束孔高分段空场嗣后充填采矿方法,其中大间距束孔布置参数是关键。通过采用理论计算法、爆破漏斗试验法、经验类比法等方法,推荐了甲玛矿束孔爆破参数,但仍需现场工业试验进一步确认与优化,为实现甲玛矿大规模机械化开采奠定基础。

台阶爆破中拒爆原因及处理方法

本文通过工程实践分析了台阶爆破中炸药拒爆的多种原因，指出了如何提高准爆率及处理拒爆孔的方法和预防拒爆的措施。

利用数值模拟技术优化光面爆破炮孔间距

利用西石门铁矿的基本岩体力学特性,通过有限元数值模拟软件ANSYS/LS-DYNA对光面爆破周边眼的耦合装药爆破过程进行模拟,在能对岩石正常崩落的同时尽可能减小对围岩的扰动,得出了较为合理的周边眼的炮孔间距为0.6 m,提高了光面爆破的效率。

地下磷块岩深孔回采爆破参数优化

随着矿山的生产规模日趋加大,地下深孔爆破技术成为目前大型地下矿山安全高效采矿的主要手段。以开阳磷矿区的马路坪矿下磷4盘区作为研究对象,通过现场声波测试分析其矿岩可爆性,结合地下实际生产情况,采用竖直扇形布孔和倾斜扇形布孔相结合的布孔方式,并进行现场爆破试验。试验结果表明:改进的布孔方式能够降低爆后矿房上部"三角区"受顶板压应力作用时的应力集中和矿房底部根底,同时提出了合理的爆破孔网参数,可以指导矿山的实际生产。