基于Aegis的无底柱分段崩落法中深孔爆破过程模拟与应用

无底柱分段崩落法因其回采效率高、结构简单、安全性高等优势被广泛应用于地下金属矿开采,其落矿方式常采用中深孔爆破。针对传统无底柱分段崩落法中深孔爆破设计过程繁琐、模拟效果不够直观等问题,开展了基于爆破设计与分析软件Aegis的中深孔爆破过程模拟与应用研究。首先介绍了该软件的模块构成和功能,并梳理和总结了模拟分析流程;其次研究了利用模型边界限制爆破空间以及利用爆炸能量的交错状态校验孔网参数的两项关键技术;最后基于该软件对某地下矿山无底柱分段崩落法中深孔爆破进行了数值模拟。研究结果表明:单排炮孔内爆炸能量集中且充盈了整个爆腔,连续耦合的装药结构以及0.3 kg/t的炸药单耗设计较为合理;临排炮孔间爆腔壁呈相切的状态,可能存在排间能量不足以完全破碎岩体的情况,2.2 m的炮孔排距稍大;预测的多条进路爆破块度质量分布结果均出现大块占比偏高的情况,与现场的工程实践结果一致,并以其中一次爆破后的爆堆照片为例进行说明,其大块率达到了18.03%。结合Aegis软件的模拟结果,分析炮孔排距偏大可能是导致大块率偏高的主要原因。此外还对实验分段的6个开采进路进行了12次爆破试验并加以模拟验证,得到了基本一致的爆破块度质量占比结果,有效佐证了该软件的现场应用效能。

Long-term observation on safety and visual quality of implantable collamer lens V4c implantation for myopia correction:a 5-year follow-up

AIM:To elucidate the safety and visual quality of implantable collamer lens with central hole(ICL V4c)implantation for correcting moderate and high myopia for at least 5y.METHODS:This retrospective study was conducted on 58 patients(114 eyes)who were followed up for at least 5y after ICL V4c implantation.The observation was done before and on 1d,1mo,1 and 5y or more after the surgical procedure.The visual acuity,subjective refraction,intraocular pressure,vault,axial length,central hole position,pupil diameter,visual quality,and adverse events were analyzed.The visual quality includes aberration,the modulation transfer function cutoff frequency(MTF cutoff),objective scattering index(OSI),Stroller's ratio(SR),and visual quality questionnaire.RESULTS:The average follow-up period was 69.25±3.80mo(range 60–82mo)and the preoperative spherical equivalent(SE)was-8.66±1.97 D.At 5y after operation,the safety index was 1.01±0.02 and the efficacy index was 0.99±0.42 and SE was-0.65±0.63 D.The 59.6%of the eyes achieved an uncorrected distance visual acuity of 20/20,76.3%of the eyes had SE within±1.0 D at the last visit.The axial length increased by 0.29±0.71 mm 5y after the surgery(t=-3.843,P<0.001).The mean vault at the last follow-up was 510.59±245.61μm.The central hole was on the temporal side in 80 eyes(84.2%).The visual quality questionnaire showed that 98.2%patients were satisfied with the surgical procedure.Adverse events occurred in 4 eyes(3.5%),including the posttraumatic toric ICL rotation(2 eyes),iris incarceration(1 eye),and posttraumatic ICL displacement(1 eye)at the last follow-up.CONCLUSION:Long-term ICL V4c implantation is safe,effective,and stable for correcting moderate and to high myopia,and the visual quality with patients is excellent and satisfactory,but the progression of axial length still needs attention after surgery.

Refractive outcomes after vitrectomy combined with phacoemulsification of idiopathic macular holes

AIM:To report the refractive outcomes after vitrectomy combined with phacoemulsification and intraocular lens(IOL)implantation(phaco-vitrectomy)in idiopathic macular holes(IMH).METHODS:A total of 56 eyes with IMH(IMH group)that underwent phaco-vitrectomy and 44 eyes with age-related cataract(ARC group)that underwent cataract surgery were retrospectively reviewed.The best corrective visual acuity(BCVA),predicted refractive error(PRE),actual refractive error(ARE),axial length(AL),were measured in both groups before and 6 mo after operation.The power calculation of IOL and the predicted refractive error(PRE)were calculated according to the SRK/T formula.The difference of PRE and ARE between the two groups were compared and analyzed.RESULTS:In the IMH group,the diameters of macular holes were 271.73±75.85μm,the closure rate was 100%.The pre-and post-operative BCVA were 0.80±0.35 and 0.40±0.35 log MAR.The PRE of A-ultrasound and IOL Master in the IMH group was-0.27±0.25 and 0.10±0.66 D.The postoperative mean absolute prediction error(MAE)was observed to be 0.58±0.65 and 0.53±0.37 D in the IOL Master and A-ultrasound(P=0.758).The PRE and ARE of the IMH group were 0.10±0.66 D and-0.19±0.64 D(P=0.102).The PRE and ARE of the ARC group was-0.43±0.95 and-0.31±0.93 D(P=0.383).The difference between PRE and ARE was-0.33±0.81 and 0.09±0.64 D in the IMH and ARC groups(P=0.021).The proportion of myopic shift was 67.9%in the IMH group and 27.3%in the ARC group(P=0.004).CONCLUSION:The myopic shift can be observed in patients with IMH after phaco-vitrectomy.

Permittivity of composites used for Luneburg lens antennas by drilling holes based on 3-D printing technique

Due to the attractive performances such as the ability of beam focus,broadband,multi-beam scanning and other features,Luneburg lens antennas are applied in multi-beam antenna,which overcomes the problem of gain loss produced by multi-beam parabolic antenna.Based on 3-D printing technique,Luneburg lens antennas by drilling holes are studied.Permittivity and loss tangent of the equivalent lens materials can be influenced by original materials,hole shapes,hole directions,and porosity.After tests,polystyrene with waxes may be the most appropriate materials for Luneburg lens with high strength.Permittivity with the shape of triangle is the lowest due to the homogeneity.Relative permittivities with the direction at a range of 15°-45°are lower while loss tangent at a range of 0°-30°.Radial directional holes are more appropriate for Luneburg lens.The relative permittivity is decreased with the increment of porosity.After calculations,the forecasts calculated by Looyenga and A-BG theory are more precise.Finally,Luneburg lens with two layers is fabricated by 3-D printing.

Macular hole following phakic intraocular lens implantation:A case report

BACKGROUND Phakic intraocular lens(pIOL)implantation has been commonly prescribed and is considered as a safe and effective option for correcting high myopia.However,it is associated with multiple complications.CASE SUMMARY This report describes a case of full-thickness macular hole(MH)in a patient with a history of bilateral pIOL implantation for the correction of myopia of–12.00 diopters in both eyes 7 mo ago.The MH closed after pars plana vitrectomy with internal limiting membrane removal and the best-corrected visual acuity improved to 20/40 in the left eye.CONCLUSION In rare cases,MH can occur following pIOL.In this present case report,we analyzed the formation process of MH following the surgery and emphasized that it is important to inform highly myopic patients about the risk of MH occurrence while being aware of the symptoms of this complication.

Magma Dynamics of Axial Melt Lens at Fast-Spreading Mid-Ocean Ridges

Multichannel seismic studies performed at fastspreading mid-ocean ridges revealed the presence of a thin(tens to hundreds of meters high), narrow(< 1-2 km wide) axial melt lens(AML) in the mid-crust, which is underlain by crystal/melt mush that is in turn laterally surrounded by a transition zone of mostly solidified material. In order to shed light on the complexity of magmatic and metamorphic processes ongoing within and at the roof of axial melt lenses, we have focused on the petrological and geochemical record provided by fossilized AMLs. Of particular significance is Hole 1256D in the equatorial Pacific drilled by the International Ocean Discovery Program(IODP), where for the first time, the transition between sheeted dikes and gabbros in intact fast-spreading crust was penetrated, providing a drill core with a more or less continuous record of the upper part of an AML(Teagle et al., 2006;Koepke et al., 2008). This can be regarded as rosetta stone to answer longstanding questions on the complex magmatic evolution within an AML, as well as on metamorphic and anatectic processes ongoing at the roof of a dynamic AML, rising upward in the midcrust as a consequence of a replenishment event. The plutonic rocks drilled from Hole 1256D consist of quartz-bearing gabbros, diorites and tonalites, which might represent the upper part of a fossilized AML. The gabbros and diorites are consistent with modeled products of MORB fractional crystallization, composed of mixed melt and cumulate in varying ratios. Modeled trace elements support a model in which the tonalites originated from low-degree partial melting of the sheeted dikes overlying the AML, rather than extreme fractional crystallization(Erdmann et al., 2015;Zhang et al., 2017a). Therefore, the upper part of AML, largely composed of low density and high-viscosity felsic magmas, may serve as a barrier to eruptible MORB melts in the lower part of AML. Zoning of apatites from three different lithologies, tonalites, diorites, and gabbros, is common and shows a consistent evolution trend with depletion in Cl and REEs from core to rim. The cores are usually homogenous in composition and interpreted as magmatic origin, whereas zones with lower Cl and REEs are disseminated with heterogeneous concentrations, indicating exchanges with hydrothermal fluids. The high-Cl apatite core indicates assimilation of high-Cl brines at a magmatic stage, which is interpreted as immiscibility product from cycling seawater-derived fluids at a high temperature(Zhang et al., 2017b). The variation of F/Cl and Br/Cl ratios of bull rocks may reflect the mixing between MORB magmas and seawater-derived fluids, crystallization of apatite and amphibole, and/or extraction of magmatic fluids(Zhang et al., 2017c).

基于FLAC^(3D)的充填体下矿柱回收方案优选

顶板失稳是威胁矿山矿柱安全回收的主要问题,某矿山为了确保安全、高效地回收矿柱,需要在矿山选定的四种矿柱回采、充填方案中优选出最优采充方案。结合矿山实际,采用FLAC^(3D)对矿柱回采方案进行分析研究。模拟结果显示,当充填体强度为2.2MPa时,采场尺寸较小,采用上向分层充填法较为保守,且对于维护采场与充填体稳定性并无显著优势,最终选择回采强度更高的浅孔留矿嗣后充填法。矿山现场试验结果表明,浅孔留矿嗣后充填法既保证了采场顶板稳定,又有效提高了矿柱回收效率和作业安全。

基于3D打印的Ku/Ka频段双波束天线设计

提出一种采用3D打印技术设计制造的径向开孔分层龙伯透镜天线,该天线以低损耗的石蜡强化聚苯乙烯为基材,透镜直径为700mm,结构形式为7层半球龙伯透镜.天线工作在Ku/Ka频段,可同时对准两个目标.研究表明:采用3D打印技术制造的低损耗介质径向开孔分层龙伯透镜天线实现了较高性能,有效解决了传统加工方式加工困难、一致性差的问题,可以容易地通过采用更小介电损耗的材料实现更优良的天线性能.

A case study of the stability of a non-typical bleeder entry system at a U.S.longwall mine

Longwall abutment loads are influenced by several factors,including depth of cover,pillar sizes,panel dimensions,geological setting,mining height,proximity to gob,intersection type,and size of the gob.How does proximity to the gob affect pillar loading and entry condition?Does the gob influence depend on whether the abutment load is a forward,side,or rear loading?Do non-typical bleeder entry systems follow the traditional front and side abutment loading and extent concepts?If not,will an improved understanding of the combined abutment extent warrant a change in pillar design or standing support in bleeder entries?This paper details observations made in the non-typical bleeder entries of a moderate depth longwall panel—specifically,data collected from borehole pressure cells and roof extensometers,observations of the conditions of the entries,and numerical modeling of the bleeder entries during longwall extraction.The primary focus was on the extent and magnitude of the abutment loading experienced due to the extraction of the longwall panels.Due to the layout of the longwall panels and bleeder entries,the borehole pressure cells(BPCs)and roof extensometers did not show much change due to the advancing of the first longwall.However,they did show a noticeable increase due to the second longwall advancement,with a maximum of about 4 MPa of pressure increase and 5mmof roof deformation.The observations of the conditions showed little to no change from before the first longwall panel extraction began to when the second longwall panel had been advanced more than 915 m.Localized pillar spalling was observed on the corners of the pillars closest to the longwall gob as well as an increase in water in the entries.In addition to the observations and instrumentation,numerical modeling was performed to validate modeling procedures against the monitoring results and evaluate the bleeder design.ITASCA Consulting Group’s FLAC3D numerical modeling software was used to evaluate the bleeder entries.The results of the models indicated only a minor increase in load during the extraction of the longwall panels.These models showed a much greater increase in stress due to the development of the gateroad and bleeder entries--about 80%development and 20%longwall extraction.The FLAC3D model showed very good correlation between modeled and expected gateroad loading during panel extraction.The front and side abutment extent modeled was very similar to observations from this and previous panels.

中央孔型ICL植入术中的改良技巧及2a临床应用观察

目的:探讨改良技巧在中央孔型ICL V4c植入术中的应用及其临床效果。方法:对2015-09/2016-08在我院行ICL V4c植入术的近视患者72例141眼采用改良手术技巧,包括2.8mm透明角膜单切口、ICL植入前免前房黏弹剂等。监测术后6h内眼内压,术后随访2a观察视力、屈光度、眼内压、角膜内皮细胞情况。结果:所有患者均成功通过透明角膜2.8mm单切口植入中央孔型ICL V4c,取得良好的效果,但术后6h内有一定的高眼压发生率,尤其是术后2h眼内压最高,95.7%的术眼眼内压能够在术后6h恢复到正常范围,且术后2a内眼内压平稳。术后6mo,1、2a本组患者累积角膜内皮细胞丢失率分别为4.70%、7.59%、9.63%。术后2a随访期间无晶状体混浊等并发症发生。结论:中央孔型ICL V4c植入术中采用的改良方法安全可行。

World-Universe Model—Alternative to Big Bang Model

This manuscript provides a comparison of the Hypersphere World-Universe Model (WUM) with the prevailing Big Bang Model (BBM) of the Standard Cosmology. The performed analysis of BBM shows that the Four Pillars of the Standard Cosmology are model-dependent and not strong enough to support the model. The angular momentum problem is one of the most critical problems in BBM. Standard Cosmology cannot explain how Galaxies and Extra Solar systems obtained their substantial orbital and rotational angular momenta, and why the orbital momentum of Jupiter is considerably larger than the rotational momentum of the Sun. WUM is the only cosmological model in existence that is consistent with the Law of Conservation of Angular Momentum. To be consistent with this Fundamental Law, WUM discusses in detail the Beginning of the World. The Model introduces Dark Epoch (spanning from the Beginning of the World for 0.4 billion years) when only Dark Matter Particles (DMPs) existed, and Luminous Epoch (ever since for 13.8 billion years). Big Bang discussed in Standard Cosmology is, in our view, transition from Dark Epoch to Luminous Epoch due to Rotational Fission of Overspinning Dark Matter (DM) Supercluster’s Cores. WUM envisions Matter carried from the Universe into the World from the fourth spatial dimension by DMPs. Ordinary Matter is a byproduct of DM annihilation. WUM solves a number of physical problems in contemporary Cosmology and Astrophysics through DMPs and their interactions: Angular Momentum problem in birth and subsequent evolution of Galaxies and Extrasolar systems—how do they obtain it;Fermi Bubbles—two large structures in gamma-rays and X-rays above and below Galactic center;Diversity of Gravitationally-Rounded Objects in Solar system;some problems in Solar and Geophysics [1]. WUM reveals Inter-Connectivity of Primary Cosmological Parameters and calculates their values, which are in good agreement with the latest results of their measurements.

Charmec MC 605 DA型装药台车在程潮铁矿的应用

程潮铁矿采用无底柱分段崩落法开采,BQ-100型装药器装药,工人劳动强度大,机械化水平低,爆破质量不稳定。为提高机械化作业水平,降低工人劳动强度,改善爆破质量,程潮铁矿引进CharmecMC 605 DA型装药台车。经过井下中深孔装药爆破试验,确定装药台车合理的工人配置为4人,适用的炸药为岩石膨化硝铵炸药。最佳工艺技术参数为炸药含水率控制在5%左右,罐内压力0.50~0.55 MPa,助推风压0.40~0.42 MPa,退管速度0.30~0.34 m/s,返粉率控制在10%左右。通过比较分析2种装药设备的优缺点,装药台车的机械化作业水平和安全性高于BQ-100型装药器,降低了工人劳动强度,爆破质量优良率提高了3%。该装药台车对国内类似矿山实现上向中深孔装药的机械化和自动化有一定的借鉴意义。

高度近视患者植入ICL V4c后眼前节参数的早期结果

目的:研究高度近视患者植入带中心孔的植入式collamer晶状体(ICL V4c)后眼前节参数的早期结果。方法:纳入2019-02/2022-09在我院行ICL V4c植入术且随访1 a的高度近视患者82例160眼,其中男42例82眼,女40例78眼,年龄26.0±4.6(21-37)岁。术前检测患者的眼前节一般特征:球镜度数、平均角膜水平曲率、水平角膜直径(WTW)和轴向长度(AL);术前,术后1 d,1 wk,1、3、6 mo测量患者的眼内压(IOP)、内皮细胞密度(ECD)、中央前房深度(CACD)、前房容积(ACV)、前房角(ACA);术后1 d,1 wk,1、6 mo,1 a测量患者ICL V4c光学区后表面中心到晶状体前表面的距离(拱高)。结果:患者术前平均球镜度数为-7.56±2.55 D,平均角膜水平曲率为42.89±1.47 D,WTW为11.64±0.37 mm,AL为26.64±0.93 mm。眼压基线为15.97±2.13 mmHg,ICL V4c植入后各时间点眼压与术前相比无差异(F=0.875,P=0.504);ECD基线为2989.30±140.78 cell/mm^(2),ICL V4c植入后6 mo的ECD与术前相比无差异(t=1.475,P=0.142);CACD基线为3.19±0.21 mm,ACV基线为210.30±27.7 mm 3,术后各时间点CACD、ACV均显著低于术前(F=111.10、288.38,均P<0.001);ACA基线为35.44°±11.27°,ICL V4c植入后各时间点ACA显著低于术前(F=21.23,P<0.001)。术后1 d拱高为665.32±184.03μm,术后1 wk,1、6 mo,1 a与术后1 d相比,拱高继续显著减少(F=52.10,P<0.001),但在术后6 mo,1 a时保持稳定,与1 mo时相比均无差异(P>0.05)。结论:ICL V4c在术后1 a的随访中具有一定安全性和有效性,植入后早期眼前节参数趋于稳定。

Dynamic assessment of variations in pupil diameter using swept-source anterior segment optical coherence tomography after phakic collamer lens implantation

Purpose To dynamically assess variations in pupil diameter induced by changes in brightness in myopic eyes implanted with an implantable collamer lens(ICL,STAAR Surgical)with a central port.Methods This prospective,observational single-center case series study comprised 65 eyes from 65 consecutive patients undergoing ICL implant.A modified commercially available swept-source Fourier-domain anterior segment optical coherence tomography(AS-OCT)device was used for imaging and performing dynamic pupillometry under changing light conditions before and after a mean follow-up interval of four months after surgery.Results Preoperative mean pupil size under photopic conditions was 3.38±0.64 mm;after surgery,this increased to 3.48±0.61 mm.Mean pupil size under scotopic light conditions was 5.72±0.79 mm before surgery and 5.84±0.77 mm postoperatively.The differences between preoperative and postoperative pupil diameter in miosis and mydriasis were 0.10±0.44 mm(P=0.078)and 0.12±0.58 mm(P=0.098),respectively.The scotopic pupil exceeded the optic zone of the implanted lens in 39 eyes(60%).The mean central vault value was 412±177μm under maximum miosis and 506±190μm under maximum mydriasis.We found a positive correlation between vault and differences in pupil diameter under all light conditions(P<0.05).Conclusion Dynamic AS-OCT enables a very precise determination of the pupillary diameter in the iris plane.The changes in the pupil diameter under different light conditions after the implantation of an ICL are related to the postoperative vault.

中厚煤层小煤柱沿空掘巷控制技术与应用

以成庄矿回采面53151巷地质条件为工程背景,拟定采用小煤柱沿空掘巷技术,现场留设6.0 m煤柱;采用“深孔预爆破卸压+锚网索补强支护+滞后注浆加固”多重支护手段;矿压监测数据表明,该巷道围岩处于稳定状态,支护措施合理有效。

黑山铁矿井下采场切割与回采过渡期损失贫化控制方法

针对黑山铁矿无底柱分段崩落法开采切割与回采过度期矿石损失贫化大的问题,分析了该时期盲区块产生及矿石损失贫化大的原因,认为下水平切割边壁对上水平布孔阻隔作用,生产中单方面考虑切割槽空间补偿作用而增大自由空间,忽略了切割边壁对上水平的后续影响,是造成扇形自由面失效形成盲区块的主要原因。由于大块主要聚集在放出体顶部,随着放矿的进行,大块提前到达眉线,不得不组织下一次爆破,导致二次矿量损失;同时,大块的存在导致其上部覆盖层小块废石沿着块体间空隙先到达出矿口,造成矿石贫化率较大。从消除盲区块与控制矿石损失贫化角度入手,根据上下水平切巷投影情况,明确了每种情况下的过渡关系,并根据上下两水平切割巷位置关系,提出了合理优化切割巷布孔参数及有效消除盲区块的矿石损失与贫化控制方法。通过现场实践,黑山铁矿井下采矿切割与回采过渡期矿石贫化率与损失率分别降低26.2%与29.3%,同时为类似条件矿山生产提供了借鉴。

长水平孔超前水力压裂治理巷道顶板技术研究

针对特厚煤层工作面回采期间伴随强矿压显现、巷道超前影响范围大、矿压剧烈、不易维护的问题,以同忻煤矿8311工作面2311巷为工程研究背景,采用长孔水力压裂原理,通过优化水力压裂参数制定了长孔水力压裂方案。结果表明:采取长水平孔超前水力压裂措施后,超前采动压力强度和范围明显降低,并且0~20^(#)支架处工作面支架阻力降低,悬顶能够及时垮落;改善了巷道围岩应力环境,有效降低了两侧采空区顶板岩层向工作面端头巷道传递应力的等级,巷道围岩变形降低60%以上;改善了工作面端头以及回采前方巷道应力结构,来压强度明显减弱,起到了调控巷道应力等级的目的,从而实现工作面安全高效回采。

武宁县大湖塘南区钨矿浅孔留矿法治理采矿的二次贫化做法

实践证明,浅孔留矿法开采二次贫化的主要原因是围岩崩落,其原因是江西巨通实业有限公司武宁县大湖塘南区钨矿的地质和开采条件所致。采取调整采场参数、优化爆破参数、锚杆加固围岩、回采时固定漏斗出矿、采空后治理采空区、治理采掘二次贫化等控制措施,对矿山进行二次贫化改造。

瑞能煤矿密集孔预裂切顶留巷技术实践

切顶卸压自动成巷技术中预裂切顶是无煤柱开采技术中重要的一环,预裂切顶效果是决定留巷质量的决定性因素之一。双向聚能爆破在预裂切缝中发挥了良好的作用,而免爆破预裂切缝成为了未来预裂切缝技术的发展趋势。在分析密集孔切顶留巷方法的基础上,通过施工一定直径、角度、深度和密度的连续孔,可以充分利用岩石的“抗压怕拉”特性,破坏岩体的连续性,使岩体抗弯强度进一步降低,从而在矿山压力的作用下,形成巷道与采空区间滑裂面,最终形成切缝线。经现场实践,采用密集孔进行预裂切缝的留巷效果较好。

Effects of overburden, rock strength and pillar width on the safety of a three-parallel-hole tunnel

During the excavation of three-parallel-hole tunnel, the tunnel might collapse due to over-stress as a result of inadequate rock pillar width. Treating the rock overburden depth, rock strength, and rock pillar width as variables, a series of 3D numerical analysis was carried out to examine the effect of each variable on the safety of the tunnel, in particular the rock pillar. A stress strength ratio (SSR) was used to define whether the safety of the rock pillar was exceeded. A simple design chart for the case of three-parallel-hole tunnel, which took into account the influence of overburden depth, rock pillar width, and rock strength, was also proposed for used in the preliminary design stage.