Treatment of Synovial Cysts in Relation to the Tibial Tunnel of Anterior Cruciate Ligament Grafts by Filling the Tunnel with Acrylic Cement

Introduction: Synovial cyst of the tibial tunnel in connection with anterior cruciate ligament (ACL) reconstruction is a rare but particularly troublesome complication. Medical treatment is often doomed to failure, and surgical treatment usually consists of excising the cyst and filling the tunnel with bone. The aim of this study was to evaluate the results of filling the tunnel with acrylic cement. Hypothesis: Filling the tibial bone tunnel with acrylic cement should eliminate communication between the joint cavity and the pre-tibial surface and prevent cyst recurrence. Patients and Methods: This retrospective series is composed of 13 patients, 9 men and 4 women, mean age 48.5 years (31 to 64) operated on between 2011 and 2019 for an intra- and extraosseous synovial cyst consecutive to the tibial tunnel of an ACL graft. Between 1983 and 2016, 12 of the patients had had a bone graft without bone block fixation (DI-DT or Mac Intosh) and one patient, a bone-bone transplant (KJ). The cyst was of variable size, located on the anteromedial aspect of the proximal end of the tibia, and often painful, warranting consultation. At the time of the initial operation, 9 patients had undergone meniscectomies (6 medial, 2 lateral, 1 double). In 7 knees, there were 7 cartilage lesions in the femorotibial and/or patellofemoral compartments (one stage 1 lesion, 2 stage 2 lesions, 4 stage 3 lesions, and no stage 4 lesions). Only 2 knees had neither cartilage nor meniscus lesions. After curettage of the bone tunnel /− removal of the non-resorbed or PEEK interference screw, the tunnel was filled with acrylic cement /− reinforced with a ligament staple to prevent expulsion. All patients underwent regular follow-up consultations until recovery. Results: At a maximum follow-up of 8 years, only 1 cyst recurred, representing a 7.69% failure rate. It was reoperated with another technique, which involved filling the tibial bone tunnel with bone graft taken from a half-bank head. After recovery, the cyst healed definitively. All patients were able to return to their previous activity within 15 days of surgery. Conclusion: Filling the tibial tunnel with acrylic cement reinforced /− with a ligament staple is a reliable and rapid solution for the treatment of intra- and extra-articular synovial cysts in relation to the tibial tunnel of ACL grafts.

COST REDUCTION OF CEMENTING FILL IN KANGJIAWAN MINE

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Strength evolution and deformation behaviour of cemented paste backfill at early ages： Effect of curing stress, filling strategy and drainage

In this study, a pressure cell apparatus is developed to investigate the early age evolution of the strength and deformation behaviour of cemented paste backfill(CPB) when subjected to various loading conditions under different curing scenarios. The different curing scenarios that are simulated include:(1)drained and undrained conditions,(2) different filling rates,(3) different filling sequences, and(4) different curing stresses. The findings show that drainage, curing stress, curing time and filling rate influence the mechanical and deformation behaviours of CPB materials. The coupled effects of consolidation, drainage and suction contribute to the strength development of drained CPB subjected to curing stress. On the other hand, particle rearrangement caused by the applied pressure and suction development due to self-desiccation plays a significant role in the strength gain of undrained CPB cured under stress.Furthermore, curing stress induces slightly faster rate of cement hydration, which can contribute to strength acquisition.

Microscopic Pore and Filling Performance of Coal Gangue Cementitious Paste

To obtain the influence laws of the fine gangue rate on the properties of coal gangue cementitious paste, the slump, divergence, stratification, bleeding, setting time and mechanical strength with the change of fine gangue rate were studied on the basis of keeping the amount of cementing material and slurry concentration unchanged. The porosity and the distribution of pore diameter of the filling specimen for curing 28 d were tested by a mercury injection instrument under different fine gangue rate conditions. It was shown that the slump, divergence, setting time and compressive strength of the paste firstly increased and then decreased with increasing fine gangue rate. The stratification and bleeding rate decreased with increasing fine gangue rate. The smaller the critical pore size of the paste was, the smaller the porosity was, the smaller the average pore size was. When the fine gangue rate was 40%, the maximum critical pore diameter of the paste was 55.79 μm, and the corresponding porosity was 17.54%, and the properties of filling paste were the best. When the fine gangue rate further increased, the aggregate surface area increased, and the reaction product of cementitious materials could not effectively fill the pores. It weakened the agglomeration effect. The particles surface of coal gangue was fragmental and flake deposit with irregular shape and uneven fold morphology. It was easy to be bonded with the surface of other filling material. The hydration products of coal gangue cementitious material were a large number of C-S-H gel with fibrous shape and ettringite（AFt） with compact block structure. The theoretical reference was provided for the preparation of low cost gangue cemented filling materials in coal mines.

Applied technique of the cemented fill with fly ash and fine-sands

Traditional stabilization of backfilling material is done by using Portland cement. However, the high price of cement forced mining engineer s to seek cheaper binding materials. Fly ash, which is the indus- trial wast e from thermal power plant, possess the potential activity of jellification, and can b e used in cemented fill as a partial substitute for cement to reduce the fill co s t. Tests were done during the past few years in Xinqiao Pyrite Mine and Phoenix Copper Mine to determine the technology parameters and the suitable content of f ly ash. Specimens with different cement/fly/ash tailings (sands) ratios were tes ted to obtain the strength values of the fill mass based on the analyses of both the chemical composition and physical and mechanical properties of fly ash . The compressive strength of specimens with a ratio of 1∶2∶8 (cement to fly ash to tailings ) can reach 2 MPa after 90 d curing, totally meeting the requiremen t of artificial pillar and reducing the fill cost by 20%-30%.

Effect of layer thickness on the flexural property and microstructure of 3D-printed rhomboid polymer-reinforced cemented tailing composites

For mines with poor ore bodies and surrounding rocks,the general mining method does not allow the ore to be extracted from underground safely and efficiently.For these mines,the downward layered filling mining technique is undoubtedly the most suitable mining method.The downward filling mining technique may eliminate the troubles relating to poor ore deposit conditions,such as production safety,ore loss rate,and depletion rate.However,in this technique,the safety of the artificial roof of the next stratum is of paramount importance.Cementitious tailings backfilling(CTB)that is not sufficiently cemented and causes collapses could threaten ore production.This paper explores a diamond-shaped composite structure to mimic the stability of a glued false roof in an actual infill mine based on the recently emerged three-dimensional(3D)printing technology.Experimental means such as three-point bending and digital image correlation(DIC)techniques were used to explore the flexural characteristics of 3D construction specimens and CTB combinations with different cement/tailings weight ratios at diverse layer heights.The results show that the 3D structure with a 14-mm ply height and CTB has strong flexural characteristics,with a maximum deflection value of 30.1 mm,while the 3D-printed rhomboid polymer(3D-PRP)structure with a 26-mm ply height is slightly worse in terms of flexural strength characteristics,but it has a higher maximum flexural strength of 2.83 MPa.A combination of 3D structure and CTB has more unique mechanical properties than CTB itself.This research work offers practical knowledge on the artificial roof performance of the downward layered filling mining technique and builds a scientific knowledge base regarding the successful application of CTB material in mines.

玻璃纤维改性煤基固废胶结充填材料性能研究

基于煤矸石、粉煤灰等煤基固废再生资源利用和胶结充填材料性能优化问题,研究了玻璃纤维掺量、长度和养护龄期对煤基固废胶结材料输送性能和力学性能的影响规律,探讨了玻璃纤维增强机理。实验结果表明:玻璃纤维改性煤基固废胶结材料坍落度随纤维长度和掺量的增大而减小,但均大于200 mm,满足输送性能要求;抗压强度和抗拉强度随纤维长度的增大呈先增高后降低,随纤维掺量的增加而增高的变化规律;当玻璃纤维长度为6 mm、掺量为0.3%时,质量分数为79%的煤基固废胶结材料的综合性能最佳;玻璃纤维改性煤基固废胶结材料水化反应后,生成的针状和团状产物填充了材料细小裂隙且附着于纤维表面,能够有效提高材料的力学性能。

水砂—胶结充填隔离矿柱稳定性及宽度研究

某嗣后充填矿山前期水砂充填泌水效果不佳,充填体富水,随着水砂充填区域增大,开采过程中顶板及上盘稳定性变差,为改善开采安全状态,改用胶结充填,水砂充填区与胶结充填区之间的隔离矿柱是保证未来采矿安全的关键。构建了侧壁承压倾斜矿柱理论分析模型,并采用FLAC3D数值模拟软件对10~15 m宽度水砂—胶结充填隔离矿柱和不同水砂充填体静水压力梯度进行了研究。研究表明:①开采扰动会使隔离矿柱内形成应力集中,且未凝固的水砂充填体会进一步增加矿柱内最大主应力;②矿柱内部应力重分布及水砂充填体水平压力使得矿柱水平变形增加,逐步产生破坏形成塑性区,10~13 m的隔离矿柱不足以保障充填体含水工况下的采场稳定性;③考虑到爆破扰动的影响,在现有富水充填情况下,建议隔离矿柱宽度为15 m;④隔离矿柱宽度15 m时,随着静水压力梯度增加,矿柱内部最大主应力和水平变形会有所增长,但塑性区未发生明显增加,15 m宽的隔离矿柱可以保障后续开采安全。

煤矿连采连充胶结充填体监测技术研究

为了对煤矿连采连充开采胶结充填体状态进行监测,基于连采连充工艺特点和充填体特性,提出了充填体状态监测的5项基本内容,主要包括液位监测、受力监测、强度监测、温度监测和应力监测,研究了各项监测内容的监测技术和监测方案。结果表明,液位监测采用浮标式液位监测技术适应性较好;受力监测采用挡墙压力计进行监测,量程约为150 kPa;强度监测通过实验室测试充填体的强度,并展望了原位强度测试技术;温度监测采用温度传感器来实现;应力监测采用千帕级和兆帕级双通道应力计进行监测。

柿树底金矿高阶段大跨度老旧隐蔽采空区安全治理实践

目的:复杂老旧隐蔽采空区的治理一直是空场法开采矿山面临的重大难题。柿树底金矿为了解决大面积、多中段、已塌陷老旧隐蔽采空区的安全治理问题。方法:通过采空区禀赋特征调查,开展了高阶段大跨度塌陷采空区似膏体非胶结充填治理技术研究与工程应用实践。结果:采用非胶结全尾砂充填治理采空区,消除了老旧隐蔽采空区的安全隐患、防止了地表的继续沉降和塌陷、避免了大规模地压灾害事故。结论:非胶结全尾砂充填治理采空区研究对于减少矿山运营成本、实现矿山固废零排放具有巨大的经济与社会效益,为国内广大空场法开采矿山的采空区治理提供了借鉴。

吹填淤泥土的双掺固化和配比优化试验研究

为了研究水泥和氧化钙双掺固化改良吹填淤泥土的最优配比,该文基于正交试验开展了双掺固化土的改性分析,最后通过模糊综合评价法对各配比方案进行了量化优选。结果表明:①同等比例掺入条件下(掺入量1.0%~4.0%),最优含水率与掺入量呈正线性相关,而最大干密度呈负线性相关;非同等比例下,规律不甚明显,但是相对水泥来说,氧化钙的减水效果要优于水泥的效果;②试样的无侧限抗压强度受水泥和氧化钙相对比例影响,等比例掺入时呈正相关,但总体上水泥在双掺固化土强度增长过程中起主要作用;③采用模糊综合评价法,综合考虑项目固化施工成本、抗压强度、击实特性等多种因素认为山东玉龙岛炼化项目吹填淤泥的最优配合比方案是采用2.0%水泥+1.5%氧化钙双固化,此时试样的最优含水率为23.3%,最大干密度为1.68 g/cm^(3),无侧限抗压强度为440 kPa。

木质纤维对充填体力学特性的影响研究

木质纤维材料凭借其强韧性、吸附性、组成元素简单的优势,在土木工程和环境工程领域得到广泛使用。为研究其作为添加剂对充填体力学性能的影响,通过充填体强度测试实验,结合SEM电镜扫描实验、EDS实验、XRD能谱分析实验,观察充填体内部水化反应程度。研究结果表明:在一定添加范围内,木质纤维提高了充填体的抗压强度,且作用效果随着灰砂比、料浆浓度的变化而改变;在应力-变形曲线峰前阶段,纤维充填体具有较高的弹性模量,在峰后阶段,纤维充填体具有较大的残余强度,能够储存的能量较高。充填体在失稳破坏后断裂而不垮,表现出良好的塑性变形;同时,木质纤维的添加利于充填体内部水化反应,内部絮状结构明显增多,增加了充填体的强度。

不同加载速率下废石胶结充填体的力学特性及破裂特征研究

为研究不同加载速率与骨料粒径级配对废石胶结充填体的力学特性以及破裂特征变化规律;对不同骨料粒径级配的废石胶结充填体进行不同加载速率的单轴压缩试验,分析其力学特性的变化规律;并辅以声发射系统,研究废石胶结充填体内部裂纹的发展演化规律。结果表明:废石胶结充填体的单轴抗压强度与弹性模量随着加载速率的增大呈线性增长趋势;废石胶结充填体的单轴抗压强度与弹性模量随着骨料级配指数的增大呈现先增长后降低的趋势;随着骨料级配指数和加载速率的增大,试样破坏模式由张拉破坏逐渐转变为剪切破坏,破坏程度加剧,完整度降低;试样内部裂纹的发展演化总体分为压密阶段、弹性阶段、稳定扩展阶段及非稳定扩展阶段。

云锡高峰山矿段矿柱回采方案研究

为了更合理地回收云锡老厂分公司残矿资源,运用FLAC3D数值模拟软件对高峰山矿段残留矿柱回采进行模拟分析,提出6种不同的矿柱回收方案,针对分析结果确定了合适的矿柱回采工艺,并开展了工业试验。结合矿山实际情况,从多个维度分析剩余矿柱是否具备回收条件和回收价值。结果表明:可采用进路规格为4 m×4 m的两步骤胶结充填采矿法进行矿柱回采,一步骤胶结充填强度大于3.52 MPa,二步骤充填强度大于1.08 MPa;矿段内有4条矿柱相对完整、保有资源量大且品位高,现阶段具备回采条件,其中南盘区4#盘区矿柱需在锡精矿市场金属价格大于24.48万元/t时进行回采,其余3条矿柱可在锡精矿市场金属价格大于10.05万元/t时进行回采。

架间底板拖管充填采空区浆液流动特性试验研究

为解决矿山充填与煤炭开采之间时空干涉难题,实现矿井安全、高效充填开采。结合李家壕矿井生产系统和开采条件,提出采空区架间底板拖管非胶结膏体充填技术。为确保该技术可行及充填参数的有据可依,遂建立非胶结膏体架间底板拖管充填采空区物理模型,以矸石和粉煤灰为骨料制备非胶结膏体充填材料,分析最大粒径和质量浓度对浆液采空区内流动特性的交互影响。研究结果表明:①浆液充填量主要受矸石粒度的影响,质量浓度主要影响浆液在采空区内的扩散速度;②随着浆液充填量的增加,采空区内的空隙逐渐趋于饱和,且渗透方式呈现出以管口为球心的半球形扩散分布;③模拟试验揭示了浆液中矸石颗粒在采空区流动扩散阻塞机理;④沿管道走向依次剖开断面,浆液中矸石级配和质量浓度有明显的分选性。

矸石胶结充填二级搅拌机优化设计及仿真分析

针对连采连充矸石胶结充填系统在长城六矿的工程应用中,二级搅拌机的出浆口时常堵塞的问题,采用Fluent欧拉多相流模型和可实现性k-ε湍流模型,运用滑移网格法对搅拌机中的固液两相流进行了瞬态模拟,并根据输出结果分析了堵塞原因,确定了优化指标。在此基础上,分别研究了转速、叶片倾角、叶轮直径和叶轮数对搅拌效果的影响,发现:提高转速、在45°以内增大叶片倾角、适当增加叶轮直径和叶轮数有助于改善搅拌效果,缓解堵塞现象,最终将二级搅拌机的优化方案确定为转速75 r/min、叶片倾角34°、叶轮直径1.3 m和5层叶轮,有效降低了罐底固液两相流的密度,提高了出浆口处灰浆的流动性。

黄土-矿渣基新型胶结充填材料强度特性试验研究

为探究黄土-矿渣基胶结充填材料在不同水胶比及养护龄期下的力学性能、破坏模式和能量演化特征,分别对黄土-矿渣基胶结充填材料在4组水胶比和5个龄期条件下进行坍落度试验和单轴压缩试验。结果发现:随着胶结材料水胶比的增大,充填材料的坍落度和扩展度增大;材料的峰值强度与水胶比呈负线性相关关系,与养护龄期呈指数型非线性相关关系;充填材料的破坏模式整体上为剪切破坏,且水胶比越小、养护龄期越长材料破坏程度越大;胶结材料破坏过程可分为压密、弹性、裂纹稳定扩展、裂纹持续扩展和峰后破坏5个阶段。

基于某矿山固废处置的水泥和胶固粉选择初探

本文以某矿固废处置及露天坑回填综合治理为背景,由于该矿全尾砂为细粒级尾砂且尾砂内含有对充填体强度具有负面作用的硫及黏土类矿物,为了选择更适合该矿全尾砂的胶凝材料,选用水泥和胶固粉两种胶凝材料对充填料浆性能进行试验研究。研究结果表明:虽然泌水沉缩特性方面水泥胶结充填体较胶固粉更优,但在充填体强度及流动性两个关键性指标方面,胶固粉性能较水泥更优且成本更低,说明胶固粉更加适用于该矿固废处置及回填治理;通过敏感性分析可知,胶固粉胶结充填体强度对灰砂比最为敏感,其次为养护龄期,最后为料浆浓度。

混杂纤维掺量对尾砂充填体力学性能的影响

为了探究混杂纤维掺量对尾砂胶结充填体力学性能的增强效果,选取三种纤维材料进行坍落度、单轴压缩和SHPB冲击试验。结果表明:纤维材料对充填体流动性影响较大,纤维掺量越高时流动性越弱,其中聚丙烯纤维对流动性影响最显著;混杂纤维对充填体的动、静力学性能提高幅度均受混杂纤维掺量影响,在一定范围内随纤维掺量增高呈现先变大后减小的趋势,0.4%聚丙烯纤维对充填体早期抗压强度增幅最为显著,28 d标准养护龄期时钢纤维对充填体动、静力学性能的提高均大于另外两种纤维;总纤维掺量在1.4%~1.5%的混杂纤维对充填体动态抗压强度提高最大,提高幅度大于更高或更低纤维掺量的方案;在相同的平均应变率下,随着混杂纤维掺量增加,充填体的反射能和吸收能先减小后增大,透射能先增大后减小。适量的混杂纤维可以有效提高充填体的力学性能,有利于充填开采的安全性,同时对矿山充填体材料设计具有一定指导作用。

矸石粉基胶结充填材料析水特性试验研究

为了探明矸石粉基胶结充填材料的析水特性,运用正交试验设计了以矸石粉、高水材料、水泥、粉煤灰为组合的胶结充填材料,采用极差分析、方差分析等方法,研究了矸石粉基质量浓度(A)、水泥含量(B)、粉煤灰含量(C)、高水材料含量(D)4个因素对胶结材料的析水率的影响情况;得到各因素对矸石粉基胶结充填材料析水特性影响的拟合公式。结果表明:基于极差分析的矸石粉基胶结充填材料的析水率影响程度为D>A>B>C,基于方差分析的材料析水率影响程度为D>B>A>C,析水率随着矸石粉浆质量分数的升高呈现下降趋势,随着水泥含量的增加则呈现先减少后增大再减少的趋势,随着粉煤灰质量增加呈现先减少后平稳的趋势,随着高水的增加呈现下降的趋势;高水含量对材料析水率的影响程度最大,矸石粉基质量分数与水泥质量对材料析水率影响相当,粉煤灰含量对材料析水率影响较小。