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.

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。

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。

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.

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.

深埋底抽巷炮掘水间隔装药结构与炮眼布置优化

为了有效解决岩巷钻爆法施工单次循环进尺较短、掘进面超欠挖等问题,以赵家寨矿14206工作面底抽巷为工程背景,采用数值模拟方法,从有效应力、振速、岩石损伤以及掘进面爆破效果等角度出发,分析了不同装药结构下岩石破碎特征。研究表明,全长装药和水间隔不耦合柱状装药结构的破碎半径相同,均为60 cm;通过巷道全断面爆破数值计算,揭示了2种炮孔间距下岩石阶段性破坏的演化规律,结果表明内部掏槽孔和崩落孔的布置间距应小于炸药有效破碎半径。现场试验结果显示,优化后的装药结构,其炮孔利用率达90%,进尺深度由1.5 m提高至1.8 m,整体装药量下降了5%。

深井扇形组合孔短延时爆破裂纹扩展模拟研究

提出了一种扇形组合孔短延时爆破的构想,即在常规的每排扇形崩落孔中间增加一排致裂孔,崩落孔与致裂孔之间短延时间隔起爆。使用ANSYS/LS-DYNA对不同延时时间及不同围压加载条件下的爆破方案进行数值模拟研究,发现高应力环境下常规扇形孔爆破无法形成有效爆破漏斗,扇形组合孔短延时爆破则损伤破裂更加有效、破岩效果更好。此外对不同围压条件下的裂纹扩展进行分析,爆破裂纹扩展趋向于最大主应力方向。数值模拟及现场工程实践证实,当最大主应力方向与扇形崩落排孔成一定小角度,即平行崩落排孔方向加载较大围压、垂直排孔方向加载较小围压时,扇形组合孔短延时爆破不仅可以改善岩石破碎效果,也可以有效保护后排炮孔和保留岩体。

Predicting the utilization factor of blasthole in rock roadways by random forest

The utilization factor of blasthole is a crucial indicator of the effectiveness of blasting in rock roadways.A significant value means that the explosive energy is fully utilized,the single-cycle advance is high,and the excavation rate is fast.A good blasting programme is a prerequisite for improving the utilization rate and predicting the utilization rate before blasting operations can verify the feasibility of the blasting programme.Firstly,a database of rock roadway blasting covering different geological and production conditions is estab-lished.Secondly,error analysis and the Gini coefficient method are used to weight the characteristic variables,quantify the importance of the variables and identify eight key indicators affecting the blasting hole utilization rate.Then,a random forest algorithm-based model for predicting utilization factor of blasthole is proposed,and the results of the model on the test set are:root mean square error(RMSE)is 0.0137,mean absolute error(MAE)is 0.0087,and coefficient of determination(R^(2))is 0.905.The performance of this method is com-pared with that of the neural network and support vector machine models on the test sets to verify the superiority of the random forest algorithm.Finally,to verify the generalization ability and practicality of the random forest prediction model,the model is applied to the rock roadway blasting construction of Gu Bei coal mine in Anhui Province.The results show that R2 is 0.913,so the model is reliable and accurate,which can meet the actual engineering requirements and lay the foundation for the promotion and application of this technology.

Study on influence of key blasthole parameters on tunnel overbreak

To determine the influence of key blasthole parameters on tunnel overbreak during blasting construction,an intelligent detection sys-tem for tunnel blasting construction is independently developed.And the key blasthole parameters and overbreak of a typical section of a single line tunnel under the condition of Class V surrounding rock are analyzed and detected.The actual data obtained is compared with the results of numerical simulations and theoretical calculations.The results are as follows:(1)Quantitative analysis is performed based on the blasthole angle,opening position,and charge mass by the self-developed intelligent detection equipment for blasthole parameters,which can be used to guide the drilling construction.Intelligent scanning equipment for outline excavation can be used to image the actual excavation section in real-time and has the advantages of high precision and fast speed;(2)Tunnel overbreak can be regarded as consisting of two parts:the surrounding rock damage caused by the blasting load,and the collapse of the surrounding rock caused by the blasthole opening position.Every parameter of the peripheral hole will affect the tunnel overbreak;however,the key parameter is the blasthole opening position;(3)The distributions of the tunnel overbreak volume obtained with the theoretical analysis,finite element simulation,and measurements are basically consistent.Under the condition of Class V surrounding rock,the overbreak of this single line tunnel can reach 14.1–78.2 cm.To meet the specification requirements,the opening position and construction accuracy of the peripheral hole should be strictly controlled.

独头隧道爆破冲击波传播特征与爆源因素影响分析

为评估在隧道爆破冲击波作用下人员安全和建筑物毁伤问题,需要明晰施工隧道与交通隧道内爆破空气冲击波传播特征的区别。利用ANSYS/LS-DYNA软件对比分析独头与双向开口隧道内冲击波传播过程的差异性,研究爆源等效炸药当量、炸药多孔起爆及爆源位置等因素对爆破冲击波传播影响机制。结果表明:独头隧道内爆破冲击波传播经历三维球面波逐渐转换至一维平面波的3阶段变化模式,且独头隧道端部边界约束初始球面波几何扩散,经壁面反射叠加的超压增幅达20%;爆源炸药当量影响着波阵面变化,3阶段变化模式的波阵面转换位置与炸药当量呈幂函数负相关关系,随炸药当量提高而在更接近爆源位置转换;多炮孔起爆工况近场超压更大,而进入远场一维平面波传播区域,多炮孔起爆和爆源位置对冲击波超压分布特征影响有限;与单个爆源中心起爆工况相比,超压相对误差小于5%。

上向中深孔掏槽爆破炮孔布置方式优化研究

以铜绿山试验采场为例,采用九孔掏槽爆破法,结合现场实际情况,并利用补偿空间理论、裂隙区理论等对中深孔爆破掏槽方式进行研究,优化其首圈掏槽爆破炮孔布置方式,并利用LS-DYNA软件建立了4种首圈炮孔布置方式模型,进行爆破仿真计算,利用RHT本构模型模拟岩石爆破效果。结果表明,空孔数量越多(即补偿空间越大),掏槽区爆破效果越好;空孔位置的均匀程度(即补偿空间的均匀程度)也会影响爆破效果。现场试验所得爆后槽区断面与高度均满足设计要求,证实首圈掏槽爆破炮孔布置方式合理。

全液压牙轮钻机可移动液压动力装置的设计

设计一种可移动液压动力装置,解决电动全液压牙轮钻机远距离行走效率低下的问题。设计中包含快速连接系统,大大提高使用效率。集成行走模式和救援模式可以为钻机行走液压系统和辅助液压系统提供动力,解决电动或柴动钻机因各类故障而无法及时转移场地的难题。利用Automation Studio软件建立辅助动力系统模型,分析系统风险点,得出了最优参数。完成了整机装配和测试,测试结果表明可移动液压动力装置满足设计要求。

白音诺尔露天坑底隔离矿柱爆破参数优化研究

针对白音诺尔铅锌矿爆破大块率高的问题,应用ANSYS/LS-DYNA软件对扇形中深孔爆破时炸药单耗和排间延时进行数值模拟分析。依据Von Mises屈服准则,分析记录单元有效应力、振速峰值和岩石损伤面积,结果表明,炸药单耗1.16 kg/m3和排间延时100 ms时记录单元的有效应力、振速峰值和岩石损伤面积均满足设计要求。将优化后的炸药单耗和排间延时应用于现场爆破,采用交错布孔的方式,实施空间交错装药结构,对爆后爆堆采用Split-Desktop 4.0进行块度分析,结果显示,爆破大块率降至4.34%,爆破大块度问题得到有效控制。

考虑炮孔密集系数及高程影响下质点峰值速度的 预测模型研究

边坡爆破作业中产生的爆破振速过大,会对周围建(构)筑物造成安全隐患,准确预测爆破峰值速度是爆破开挖的重要指标。基于量纲分析理论,推导并改进炮孔密集系数及高程影响下的质点峰值速度预测公式。结果表明:引入边坡坡度项(H/D)的经验公式预测精度均大于萨氏公式及萨氏修正公式;推导并改进的预测模型能较为准确地预测峰值速度,预测精度达到91.16%;结合多次爆破测振试验获得实测爆破振动数据,分别代入萨氏公式、萨氏修正公式以及通过无量纲理论推导的质点峰值振速公式进行非线性回归运算,得到改进的峰值速度公式与各峰值速度公式的相对误差分别为8.84%、13.32%和19.74%。炮孔密集系数的预测模型比萨氏公式、萨氏修正公式的精度分别提高了10.90%和4.48%,并且在实际工程中取得了良好效果,说明了预测公式的可行性,可为类似爆破工程提供参考。

Dynamic response of water-rich tunnel subjected to plane P wave considering excavation induced damage zone

The stability analysis of a deep buried tunnel subjected to dynamic disturbance is an important issue.In this study,the transient response has been obtained by establishing a water-rich tunnel model considering excavation damage zone(EDZ).Based on Biot’s two-phase dynamic theory and wave function expansion method,the analytical solution of dynamic response around the water-rich tunnel containing EDZ subjected to P wave is derived.Moreover,Fourier transform and Duhamel’s integral technique is introduced to calculate the transient response,and the equivalent blasting curve is adopted to input excitation function.The dimensionless parameters thickness N and shear modulus ratio lare defined to characterize the degree of damage in the surrounding rock,investigating the influencing factors,such as the parameters and the incident source frequencies.The results indicate that the dynamic stress concentration factor(DSCF)gradually decreases as the dimensionless parameters increase.Additionally,it is observed that the DSCF is more sensitive to changes in the thickness parameter N.Finally,the influence of the waveform parameters has been taken into account in the analysis of transient response,and the stress state and transfer process in each time stage of the EDZ are analyzed.This study establishes a theoretical foundation for comprehending the mechanical behavior and support design considerations associated with a deep-buried water-rich tunnel containing EDZ.