Application of high-pressure water jet technology and the theory of rock burst control in roadway

This paper puts forward using high-pressure water jet technology to control rock burst in roadway, and analyzes the theory of controlling rock burst in roadway by the weak structure zone model. The weak structure zone is formed by using high-pressure water jet to cut the coal wall in a continuous and rotational way. In order to study the influence law of weak structure zone in surrounding rock, this paper numerically analyzed the influence law of weak structure zone, and the disturbance law of coal wall and floor under dynamic and static combined load. The results show that when the distance between high-pressure water jet drillings is 3 m and the diameter of drilling is 300 mm, continuous stress superposition zone can be formed. The weak structure zone can transfer and reduce the concentrated static load in surrounding rock, and then form distressed zone. The longer the high-pressure water jet drilling is, the larger the distressed zone is. The stress change and displacement change of non-distressed zone in coal wall and floor are significantly greater than that of distressed zone under dynamic and static combined load. And it shows that the distressed zone can effectively control rock burst in roadway under dynamic and static combined load. High-pressure water jet technology was applied in the haulage gate of 250203 working face in Yanbei Coal Mine, and had gained good effect. The study conclusions provide theoretical foundation and a new guidance for controlling rock burst in roadway.

In situ experimental study on TBM excavation with high-pressure water-jet-assisted rock breaking

China’s first high-pressure hydraulically coupled rock-breaking tunnel boring machine(TBM) was designed to overcome the rock breaking problems of TBM in super-hard rock geology, where high-pressure water jet system is configured, including high-flow pump sets, high-pressure rotary joint and high-pressure water jet injection device. In order to investigate the rock breaking performance of high-pressure water-jet-assisted TBM, in situ excavation tests were carried out at the Wan’anxi Water Diversion Project in Longyan, Fujian Province, China, under different water jet pressure and rotational speed. The rock-breaking performance of TBM was analyzed including penetration, cutterhead load, advance rate and field penetration index. The test results show that the adoption of high-pressure water-jet-assisted rock breaking technology can improve the boreability of rock mass, where the TBM penetration increases by 64% under the water jet pressure of 270 MPa. In addition, with the increase of the water jet pressure, the TBM penetration increases and the field penetration index decreases. The auxiliary rock-breaking effect of high-pressure water jet decreases with the increase of cutterhead rotational speed. In the case of the in situ tunneling test parameters of this study, the advance rate is the maximum when the pressure of the high-pressure water jet is 270 MPa and the cutterhead rotational speed is 6 r/min. The technical superiority of high-pressure water-jet-assisted rock breaking technology is highlighted and it provides guidance for the excavation parameter selection of high-pressure hydraulically coupled rock-breaking TBM.

Dynamic effects of high-pressure pulsed water jet in low-permeability coal seams

Mine gas extraction in China is difficult due to the characteristics such as micro-porosity,low-permeability and high adsorption of coal seams.The pulsed mechanismof a high-pressure pulsed water jet was studied through theoretical analysis,experimentand field measurement.The results show that high-pressure pulsed water jet has threedynamic properties.What's more,the three dynamic effects can be found in low-permeabilitycoal seams.A new pulsed water jet with 200-1 000 Hz oscillation frequency andpeak pressure 2.5 times than average pressure was introduced.During bubble collapsing,sound vibration and instantaneous high pressures over 100 MPa enhanced the cuttingability of the high-pressure jet.Through high-pressure pulsed water jet drilling and slotting,the exposure area of coal bodies was greatly enlarged and pressure of the coal seamsrapidly decreased.Therefore,the permeability of coal seams was improved and gas absorptionrate also decreased.Application results show that gas adsorption rate decreasedby 30%-40%and the penetrability coefficient increased 100 times.This proves that high-pressurepulsed water is more efficient than other conventional methods.

Generalized equation for calculating rock cutting efficiency by pulsed water jets

One of the promising methods for rock cutting technology is the use of high-speed water jets.In order to improve the cutting capacity of water jets without increasing the hydraulic power of equipment,pulsed water jets are basically used to increase the rock cutting efficiency.However,there are no mature recommendations for selection of rational parameters,and the relationship between indicators of rock cutting efficiency and parameters of pulsed water jet is still not established.In this context,we aimed at developing a generalized equation for calculating rock cutting efficiency,in which all the major parameters in consideration of rock cutting process are included.Then,a calibration of the rational parameters of rock cutting by pulsed water jets was conducted.The results are likely helpful for increasing productivity and reducing energy consumption.

Prevention and treatment technologies of railway tunnel water inrush and mud gushing in China

Water inrush and mud gushing are one of the biggest hazards in tunnel construction. Unfavorable geological sections can be observed in almost all railway tunnels under construction or to be constructed, and vary in extent. Furthermore, due to the different heights of mountains and the lengths of tunnels, the locations of the unfavorable geological sections cannot be fully determined before construction, which increases the risk of water inrush and mud gushing. Based on numerous cases of water inrush and mud gushing in railway tunnels, the paper tries to classify water inrush and mud gushing in railway tunnels in view of the conditions of the surrounding rocks and meteorological factors associated with tunnel excavation. In addition, the causes of water inrush and mud gushing in combination of macroand micromechanisms are summarized, and site-specifc treatment method is put forward. The treatment methods include choosing a method of advance geological forecast according to risk degrees of different sections in the tunnel, determining the items of predictions, and choosing the appropriate methods, i.e. draining-oriented method, blocking-oriented method or draining-and-blocking method. The treatment technologies of railway water inrush and mud gushing are also summarized, including energy relief and pressure relief technology, advance grouting technology, and advance jet grouting technology associated with their key technical features and applicable conditions. The results in terms of treatment methods can provide reference to the prevention and treatment of tunnel water inrush and mud gushing.

Discussion on Anti-Seepage Technologies in the Construction of Small-Scale Rural Water Conservancy Projects

In order to ensure the sustainable growth of rural economy,it is necessary to carry out further research on small-scale water conservancy projects and solve the seepage issue in rural areas.Based on the application significance of small-scale rural water conservancy projects and the analysis of anti-seepage technologies,along with specific examples,this paper specifically discusses the application of high-pressure jet technology,so as to provide reference for the development of engineering construction.

基于机器学习的K424合金刻蚀深度预测

为探究水导激光加工过程中不同工艺参数对K424高温合金刻蚀深度的作用,对K424高温合金进行了包括激光功率、进给速度及加工次数在内的三个关键工艺参数的影响刻蚀实验,实验结果表明:较大的功率、较小的进给速度和多次加工会产生更深的刻蚀。此外采用XGBoost、RF、BPNN以及SVR四种模型建立了激光功率、进给速度和加工次数与加工深度之间的预测模型。在拟合效果上XGBoost与SVR模型表现优异,最大误差百分比均不到0.3%;在预测结果方面显示,XGBoost最大误差百分比6.698%,优于另三种模型。最后得出XGBoost模型在拟合和预测K424高温合金加工深度方面有更好的性能。与传统的干式激光加工相比,水导激光加工技术减少了材料热损伤,提高了加工质量。该研究为水导激光加工K424高温合金提供了参考。

医用水射流在不同力学性能皮肤上的注射效果研究

为探究不同力学性能皮肤对无针注射效果的影响,通过注射不同质量分数的凝胶皮肤模型进行注射效果分析。首先,通过自制压力测试平台,分析不同注射参数下气动式无针注射系统微射流动力学特征;其次,采用气动式无针注射系统分别开展凝胶注射试验与离体猪肉组织注射试验,探究凝胶注射试验的可靠性;在此基础上,分别开展单层、双层及多层凝胶注射试验,探究多层结构组织及不同层间界面条件下气动式无针注射系统微射流的扩散特征。研究结果表明:随着凝胶弹性模量增大,注射深度、扩散面积和注射完成率均减小;同时,分界面一定条件下起到促进药液横向扩散作用,疏松界面一定会出现层间积液,紧密界面可能出现层间漏液现象。研究结果可为无针注射系统在不同力学性能皮肤条件下的进一步发展应用提供理论依据和技术支撑。

基于水射流技术的禽舍冲洗设备研究

全球禽类养殖业迅速发展,传统禽舍清洁方法存在效率低、耗时长等问题,制约了行业的可持续发展。为解决这一问题,研究了一种基于水射流技术的禽舍冲洗设备,利用高压水射流和智能化控制系统,能够快速高效地清除禽舍内的粪便和污染物,同时最大限度地减少水资源消耗和环境影响。研究从机械结构设计、水力学性能优化到智能控制系统开发等多个方面进行了系统性研究,以期为禽舍清洁设备研发提供参考。

N-JET隔断车站基坑深层承压水的应用

结合宁波地铁工程,南高教园区站5-ⅠB区承压水抗渗流系数不满足设计要求,周边环境要求较高,存在敏感建筑物或管线的情况下,降水已无法满足变形控制要求。面对该难题,车站基坑采用N-JET高压旋喷桩(半圆形)切断⑧层承压水层,高压旋喷桩桩顶高于地墙墙趾以上2 m,紧贴地墙并穿透⑧层承压水层底以下2 m。论证表明,N-JET高压旋喷桩对隔断深层承压水具有较好的效果。

喷水推进泵内窥式非定常流场测量技术

为了突破壳体引起的视场粒子图像局部畸变限制,实现泵内多关键流场信息精细化测量,将内窥镜技术与粒子图像测速(PIV)技术相结合,提出了适用于喷水推进泵的内窥式PIV非定常流场测量方法。以前置导叶喷水推进泵为研究对象,采用该方法测量了导叶前、叶轮后及静动间轴截面非定常、周期性流场速度分布,分析了不同工况下泵内多关键流域的流动规律与特性。试验结果验证了该方法的可行性。

驱动压力调节对可控型射流注射系统性能的影响

为探究驱动压力调制对可控型射流注射系统动力学特征及注射性能的影响,利用高精度射流冲击测试平台及高速摄影装置,分析射流冲击变化特征及扩散特征,并结合离体组织注射试验结果探究驱动压力调制机理。研究结果表明,通过驱动压力切换可以达到可控型射流注射系统高、低两段式射流速度的要求,且通过控制驱动压力可以实现对射流注射系统的冲击特征及扩散特征进行控制。不同喷射剂量工况均存在较优驱动压力组合,典型大剂量注射工况1.0 mL的最优驱动压力组合为(1.00—0.25) MPa,通过驱动压力调制可以进一步提高可控型射流注射系统的注射性能。

基于声发射的超声辅助AWJ冲蚀实验研究

超声辅助磨料水射流具有良好的流动特性,有效提高了射流的加工效率与精度。为了进一步研究其冲蚀能力,通过实验研究了超声辅助磨料水射流(AWJ)冲蚀动态响应规律,基于声发射检测技术研究了超声辅助磨料水射流冲蚀动态响应情况,对信号进行采集处理,分析了射流压力、靶距以及超声振幅等参数对其冲蚀动态响应的影响规律。结果表明:声信号随着射流压力的增大而不断增强,冲蚀深度不断增大;随着靶距与超声振幅的不断增大,声信号呈现先变强后变弱的趋势,冲蚀深度先增大后减小,即存在最佳靶距与最佳超声振幅;声信号频率主要分布于0~200kHz之间。

综采工作面综合防尘技术研究

为解决传统喷雾降尘系统除尘效果差的问题,对工作面生产情况进行分析,本文利用文丘里式喷雾和水射流卷吸机理对工作面喷雾系统进行优化改造,设置采煤机喷雾+支架喷雾+工作面挡风帘的多点位、多形式综合除尘系统,并对除尘效果进行验证。结果显示全尘和呼尘的除尘效率分别为92.03%和91.12%,除尘效果较好。

水利水电工程中高压喷射灌浆技术

在我国工程建设工作进行的过程中,水利工程建设是一项重要的工作,它不仅可使我国的农业生产得到更好的发展,同时也具备抗洪、蓄水等作用,因此,我国的水利工程施工正在受到越来越多的关注和重视。以某项目为例,对水利水电工程施工中的高压喷射注浆技术进行了较为详细的阐述和分析。

深中通道深厚砂层高压旋喷桩止水帷幕施工工艺研究及应用

深中通道西人工岛采用插入式钢圆筒及弧形钢板副格围闭的方案快速形成岛体结构。岛内陆域形成采用深井降水联合回填砂大超载比堆载预压进行岛内软基处理。地基处理后,在岛内进行明挖现浇隧道施工。由于人工岛所在海域钢圆筒底部多为粗砂、砾砂、砂砾状强风化岩、碎块状强风化岩,与海水联通,具有较高的渗透性。为满足西人工岛基坑内的渗流稳定和突涌稳定要求,达到止水的效果,采用在钢圆筒及副格内侧设置3排高压旋喷桩止水帷幕阻断钢圆筒围护结构岛内外的渗流路径。对外海深厚回填砂层高压旋喷止水帷幕施工工艺进行系统研究,通过工艺试验论证,确定最优施工参数并优化调整施工工艺,为类似工程提供经验借鉴。

隧道钻进富水砂层地段水平旋喷桩技术探讨

地铁建设过程中经常穿越浅埋第四系富水砂层,水平旋喷桩技术是处理此工况的有效手段。论文根据现场实际施工情况,提出了水平旋喷内插管棚工法,通过现场试验证明了此工法的可行性,并对其工艺及设备进行了改进。

水利水电工程防渗施工技术探讨

随着水利水电工程项目建设速度的不断加快,防渗问题和相关的施工技术成为该领域的研究重点。文章针对水利水电工程项目中渗漏问题的影响因素以及防渗施工技术的应用现状进行了讨论,总结了灌浆防渗技术、射水防渗墙技术和碾压混凝土抗渗透技术的特点及应用条件,并结合应用灌浆防渗技术的实际案例,分析了实际项目工程的防渗处理效果。通过对项目防渗技术应用的研究可知,需要结合项目的实际地质条件和参数选择防渗技术,采用合理的防渗技术能够有效解决项目的渗透问题,可以进一步提升项目的施工质量,保障工程的安全性。

向斜构造区内动压巷道围岩水射流防冲技术研究

针对砚北矿区向斜构造区内2502采区内巷道围岩动压显现频发难题,通过现场调研、实验室测试和理论分析的方法对动压巷道围岩冲击机理进行了研究,基于此,阐释了水射流防冲机理并进行了现场工业性试验。研究结果表明:煤样经过饱和水软化处理后,冲击倾向性由强冲击转变为弱冲击;采动引起的动载荷和巷道围岩内积聚的静载荷叠加作用是导致围岩诱发冲击的根本原因,且可划分为动载荷主导型和静载荷主导型2种类别;水射流防冲技术能够在巷道两帮内形成弱结构区,有效地转移和释放两帮内原有高集中静载荷,进而实现对于巷道两帮和底板的冲击防治目的。现场实施水射流防冲技术后电磁辐射信号平均值由49.7mV减小至15.6mV,同时巷道两帮和顶底板移近量均控制在5%以内,有效保证了巷道围岩的应力环境和支护控制效果。