Rock Breaking Performance of a Pick Assisted by High-pressure Water Jet under Different Configuration Modes

In the process of rock breaking, the conical pick bears great cutting force and wear, as a result, high-pressure water jet technology is used to assist with cutting. However, the effect of the water jet position has not been studied for rock breaking using a pick. Therefore, the models of rock breaking with different configuration modes of the water jet are established based on SPH combined with FEM. The effect of the water jet pressure, distance between the jet and the pick bit, and cutting depth on the rock breaking performance as well as a comparison of the tension and compression stress are studied via simulation; the simulation results are verified by experiments. The numerical and experimental results indicate that the decrease in the rates of the pick force obviously increases from 25 MPa to 40 MPa, but slowly after 40 MPa, and the optimal distance between the jet and the pick bit is 2 mm under the JFP and JSP modes. The JCP mode is proved the best, followed by the modes of JRP and JFP, and the worst mode is JSP. The decrease in the rates of the pick force of the JCP, JRP, JFP, and JSP modes are up to 30.96%, 28.96%, 33.46%, 28.17%, and 25.42%, respectively, in experiment. Moreover, the JSP mode can be regarded as a special JFP model when the distance between the pick-tip and the jet impact point is 0 mm. This paper has a dominant capability in introducing new numerical and experimental method for the study of rock breaking assisted by water jet and electing the best water jet position from four different configuration modes.

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.

Numerical analysis on coal-breaking process under high pressure water jet

Based on the theory of nonlinear dynamic finite element,the control equation ofcoal and water jet was acquired in the coal breaking process under a water jet.The calculationmodel of coal breaking under a water jet was established;the fluid-structure couplingof water jet and coal was implemented by penalty function and convection calculation.The dynamic process of coal breaking under a water jet was simulated and analyzed bycombining the united fracture criteria of the maximum tensile strain and the maximal shearstrain in the two cases of damage to coal and damage failure to coal.

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.

High Pressure Water-Jet Technology for the Surface Treatment of Al-Si Alloys and Repercussion on Tribological Properties

Recent developments in high pressure water-jet technology have brought the process to the forefront as a means of surface treatment. Water jet technology offers cleaning, cutting, processing as well as potential refinement of surface properties. By adapting the process parameters the surface characteristics can be changed while the profile remains the same. In the present study, water-jet technology was used for the surface treatment of Al-Si alloy to investigate its effect on tribological properties. Dry sliding wear behavior was investigated against AISI 52100 bearing steel ball using a reciprocating ball-on-flat configuration. Optical microscopy examination reveals that ploughing of grains, transgranular and intergranular propagation of cracks;are the mechanisms by which material is removed during water jet treatment. While, on the other hand, SEM observation of the wear track reveals that plastic deformation and delamination are the dominant wear mechanism during the wear process. Water jet treatment was compared to hot isostatic pressing in terms of its effects on wear resistance and surface porosity of Al-Si alloy. It was found that, hot isostatic pressing reduces the total amount of porosity at the expanse of hardness while water jet treatment produces a compressed surface having higher hardness and compressive residual stress, which ultimately increases wear resistance.

Investigation on Water Jet Treated Polyester/cotton Blended Cambric

Analytical examination was made to ascertain the effect of the high pressure water flow on the fabric properties.Polyester/cotton blended cambric was spurted by high pressure water flow. Fabric properties such as handle,thickness, tensile strength , stiffness and air permeability after the water treatment were investigated.

地面井分层卸压的煤系气合采原理及方式探讨

为了进一步认识制约煤系气合采的因素,提高煤系合层排采各产层的产气贡献,分别从动力、通道和气源条件出发,分析了煤系气合采的必备因素。基于改变地应力状态提高储层导流能力以及分层改变储层流体压力,满足多层合采动力条件的原理,提出了地面井分层卸压的煤系气合采方式。该方式通过在地面进行定向钻井,在目标储层中进行高压水射流作业,人工创造卸压空间(缝、槽、穴等),改变地应力状态,降低有效应力伤害,增加储层导流通道的数量和开度,提高目标储层压降传递速率。待储层压力降至符合煤系气合采动力条件时进行合层排采,从而提高煤系合采各产气层的产气贡献。相较于常规增产改造措施,此方式能够减少煤系气储层在有效应力作用下的储层伤害,且有助于提高储层压降传递效率,增强煤系气的解吸和扩散,降低多层煤系气合采过程中的层间干扰。在以上研究基础上,认为地面井分层卸压的合采方式主要适用于储层地应力大、产层间距小的煤系气储层,且有望在薄互层煤系气储层增产改造及层间干扰严重的叠合共生煤系储层开发领域进行应用推广。

基于5DOF的隧道摄像头清洗装置控制系统设计

针对隧道内摄像头镜面污染严重,影响隧道监控管理的问题,基于高压水射流技术,提出了一种5自由度的机械臂清洗装置。分析系统的功能需求,采用电驱动的方式对机械臂的控制系统进行设计,基于比例积分微分控制(PID)原理设计了各关节的定位功能,并用物联网监控的方式开发了远程APP测控系统。通过室内实验确定了最优的清洗工艺参数,并进行了现场的清洗实验。实验结果表明:其能够实现隧道摄像头镜面的有效清洗,清洗装置各关节的定位相对误差在1.4%以内,为隧道内摄像头或者标识物的清洗提供了安全高效的机械化方式。

高燃压中型运载火箭发射地面低高度排导技术

综合高燃压中型运载火箭高密度发射燃气流地面排导需求及烧蚀风险分析,提出基于地面双面导流装置与高位挡流墙结合的地面低高度排导技术方案。利用火箭发射燃气动力学研究总结的燃气流膨胀特性以及导流型面设计方法,解决了地面低高度排导技术涉及的地面导流装置导流型面气动设计以及尺度控制两个关键问题。地面低高度排导技术方案设计与燃气流场瞬态仿真多轮叠代,实现了燃气流排导烧蚀范围合理控制,避免了燃气流低高度排导烧蚀反溅影响箭体。地面低高度排导技术采用专利支撑的喷水冷却防护方案实现高燃压中型运载火箭发射燃气流强烧蚀环境发射系统、发射设施综合防护。基于喷流缩比试验相似性控制方法研制了1∶10比例喷流缩比试验系统,通过喷流缩比试验验证确认高燃压中型运载火箭发射燃气流能够实现地面低高度安全、顺畅排导,同时与发射台、导流装置结构融合的阵列喷水方案能够行之有效解决高燃压中型运载火箭地面低高度排导强烧蚀难题。

基于正交试验法的铝合金车体高压水清洗喷嘴结构优化

抑尘剂等复杂的化合物黏着在铝合金车体上,导致车体污染十分严重,高压水射流清洗方法能够有效去除铝合金车辆车体表面黏着的化合物。通过分析圆柱形、锥形、文丘里形和余弦形喷嘴的射流流场分布、射流出口速度、最大壁面静压、相同清洗宽度下压力值范围,得到余弦形喷嘴的清洗性能最佳,锥形喷嘴次之。基于正交试验法设计五因素、四水平正交试验表,得到常用清洗压力下余弦形喷嘴的最优结构参数:进口直径为40 mm、出口直径为20 mm、过渡段半径为40 mm、出射段长度为25 mm、过渡与余弦部分长度比为4。按照最优喷嘴结构参数进行建模,得到三组压力值下高压水出射速度比未优化前提高了2%,且优化效果随着入口压力值的提高而有所下降。在优化后的喷嘴结构参数下进一步计算得出入口压力为10 MPa时,靶距设置为250 mm能达到较好的清洗效果和节能作用。

三轴搅拌桩组合高压旋喷桩入岩落底式止水帷幕施工技术

某房建深基坑工程支护形式采用排桩+落底式止水帷幕,场地地质条件上部为富水深厚砂层,下部为强风化岩层,止水帷幕需穿透强风化岩0.5 m,以隔断强透水层。通过对地质情况及现有设备条件分析,采用大功率桩机先行施工三轴搅拌桩,养护后进行桩体质量抽芯验证,再针对不同缺陷程度采用高压旋喷桩分别进行补强的组合工艺施工止水帷幕。基坑开挖结果表明,该落底式止水帷幕效果良好,能有效隔断强透水层,与灌注排桩结合形成深基坑支护结构体系具有较高的经济性、适用性。

坚硬顶板高压磨料射流侧向切顶煤柱卸荷技术研究

针对坚硬顶板下临空巷道存在的高应力、大变形、难支护等问题,分析了磨料射流能量分布情况,研究了磨料颗粒及高压水射流的冲击破岩作用。基于“砌体梁”原理,建立不同岩性条件下的岩层周期破断力学模型,研究了巷道侧向切顶条件下上覆岩层断裂情况,采用数值模拟分析切顶前后煤柱应力变化情况,提出了磨料射流侧向切顶煤柱卸荷技术。现场试验结果表明,采用磨料射流切顶后巷道高度变形量减小38.7%,宽度变形量减小45.8%,巷道变形得到有效控制。同时,切顶后每日最大总能量降低85.5%,平均每日总能量降低82.6%。验证了磨料射流侧向切顶对坚硬顶板的弱化效果,为坚硬顶板弱化治理提供了一种新的技术手段。

高承压性富水卵砾石地层中N-JET工法试验及质量效果分析

为探索研究高承压性富水卵砾石地层的止水帷幕施工,选取北京轨道交通某施工现场,采用N-JET工法施作超高压旋喷桩,以期完成不同桩径和不同角度的止水旋喷桩(墙)和封底工程的试验施工。同时结合超前桩体质量检测技术和实际开挖验证方法,揭示超高压旋喷桩(墙)和封底的止水效果。针对试验结果,进行了成功经验总结和不足原因分析,研判在北京相似水文地质条件工程中实际应用的可能性,并提出了下一步技术创新改进建议。

松软煤层水力割缝缝槽形态控制技术研究及应用

为解决松软煤层(f>0.2)超高压水力割缝期间缝槽发育难控制、易垮孔等问题,通过理论分析手段,分析了割缝缝槽周围煤体应力分布规律,获得了割缝缝槽周围煤体塑性区分布影响因素。研究了高压水射流破煤规律,得到了影响割缝缝槽形态的主要因素为割缝压力、喷嘴直径及煤体自身硬度。提出了基于松软煤层特点的超高压水力割缝缝槽形态控制技术,获得了控制松软煤层缝槽深度、宽度以及发育速度的关键参数为割缝压力、喷嘴直径及压力调节速度。通过现场应用表明,针对松软煤层其缝槽形态控制合理参数为:割缝喷嘴直径2.5~3.0 mm,割缝压力70 MPa,割缝调压间隔3~5 min。验证了松软煤层水力割缝缝槽形态控制技术适用性,可效提高松软煤层水力割缝施工成功率及安全性。

深圳市某地铁车站深基坑底部涌水治理技术探析

在灰岩富水岩溶区、褶皱破碎断裂带进行地铁车站深基坑施工,要面临许多施工不确定,尤其是深大基坑开挖至邻近垫层标高坑底涌水是工程施工中的重大事故隐患,迅速、精准查找出涌水通道和涌水原因是处置解决问题的首要任务。以深圳某地铁车站深基坑开挖过程中涌水为背景,全面、系统分析了形成涌水的原因,针对深基坑底部水力劈裂型涌水具体工况,采取了行之有效的应对措施,使得涌水得以治理,保证了基坑后续施工正常进行。

水利工程施工中堤坝防渗加固技术研究

在水利堤坝工程建设实践中,防渗加固技术的应用与控制在很大程度上决定着工程整体质量安全,不仅能消除潜在的渗漏问题,还能显著延长工程使用寿命,确保水利设施的性能得到充分发挥。为此,为保证水利堤坝工程项目安全稳定运行,必须科学选取防渗加固技术应用,实现对特殊地层的灌浆加固处理。本文以某具体水利工程项目为例,针对该项目建设中高压喷射灌浆技术应用情况展开论述,期许通过本研究能为同类型工程项目建设提供技术借鉴与指导。

Jetstream高压泵在油田行业径向水射流技术中的应用

近年来的开发实践表明,由水平井衍生的零半径径向射孔技术是低渗透油气藏增产、增效的有效技术,正发挥着重要的作用。而Jetstream始终提供最先进的高压水射流技术并与专业径向射孔设备公司保持着紧密的合作,推动高压水射流技术在径向射孔的成功应用。

THE PERFORMANCES OF HIGH PRESSURE JET OF PURE WATER AND POLYMER SOLUTION WITH CONICAL NOZZLE

In this paper, the effects of polymer additives and nozzle shape on the proper- ties of high pressure water jet discharging into the air are investigated by theory and experiments. Criteria of judging the jet quality are put forward. And, a method that can be used in analysing the fluid flow within the nozzle is developed. Then, the calculated results are compared with the experiments that we carried out; it is shown that the degree of agreement between the two is good. At last, the mechanism to improve on the jet quality with polymer additives is discussed.

高压旋喷修复中水溶性药剂径向迁移规律研究

高压旋喷修复是近年来出现的污染土原位修复技术,目前对于旋喷药剂的迁移规律尚不明确,工程实践缺乏可靠的理论指导。分别以荧光素钠及氯离子为示踪剂,开展不同旋喷参数下的现场及室内高压旋喷试验,并结合数值模拟研究了射流作用及对流-扩散作用下的药剂径向迁移规律。现场旋喷5 d后的结果表明,药剂质量浓度沿径向逐渐降低,分布受旋喷参数影响明显,现场最佳旋喷参数组合为注入压力25 MPa、旋转速度22 r/min、提升速度25 cm/min、喷嘴直径1.6 mm、旋喷2次。室内旋喷试验和数值模拟表明,射流作用下混合区内药剂质量浓度线性减小,喷嘴附近相对质量浓度为0.54~0.91;混合区半径随注入压力、喷嘴直径及旋喷次数的增加而增大,随旋转速度的增加而减小;药剂质量浓度及径向均匀性与旋转速度、喷嘴直径及旋喷次数呈正相关,对流-扩散作用下的药剂迁移使混合区内质量浓度降低,扩散区质量浓度升高,径向分布趋向均匀;虽然孔压消散仅需短短几分钟,但其引起的对流在约30 d内对药剂迁移起主导作用,之后扩散变为主要作用。

矿山建设中现代破岩方法综述

随着我国资源开发逐步进入深部开采阶段,深部高硬度岩(矿)石对目前地下工程中岩石破碎提出了新的挑战,各类新型破岩手段应运而生。高压水射流破岩、微波破岩以及液氮低温破岩作为三种热门新型破岩方法已被广泛研究,三种破岩方法的发展历程、工作原理以及适用场景各不相同,但是均具有广阔发展前景。在未来深部坚硬岩石地层环境中,相关研究成果以及理论方法可以为安全、高效、经济及绿色的资源开发提供一定理论基础与技术支撑。