High Water Content Material Based on Ba-Bearing Sulphoaluminate Cement

A new type of high water content material which is made up of two pastes is prepared, one is refute from lime and gypsum, and another is based on Ba-bearing sulphoaluminate cement. It has excellent properties such as slow single paste solidifing ,fust double pustes solidifing ,fast coagulating and hardening, high early strength, good suspeasion property at high W/C ratio and low cost. Meanwhile, the properties and hydration mechanism of the material were analyzed by using XRD, DTA- TG and SEM. The hydrated products of new type of high water content material are Ba-bearing ettringite, BaSO4 , aluminum gel and C-S-H gel.

Internal Curing Using Water-releasing Material for High Strength Micro-expansive Concrete

Due to its low water content, it is difficult for expansive agent to have an effective expansive effect on high strength concrete to compensate its extensive shrinkage and form a certain expansion. To solve this problem, water-releasing material with water storage and releasing characteristics was incorporated into high strength micro-expansive concrete to provide internal curing, and expansive effect of expansive agent was improved. Migration of water from initially saturated water-releasing material to the surrounding hydrating cement paste was investigated. Based on a given efficient diffusion distance of water stored in water-releasing material, the mass and real water-cement ratio of cured cement paste were estimated. At the same time, the effect of internal curing of water-releasing material on the volume deformation of high strength micro-expansive concrete was investigated.

Research on the width of filling body in gob-side entry retaining with high-water materials

To determine the filling body's width along the gob-side remained roadway which is underneath the gob,the authors analyzed the interaction mechanism between the roof and the supporting body along the remained roadway, based on the elastic thin plate theory of the stope roof. The stress state and mechanical response of the filling body along the remained roadway were studied. Specifically, firstly, the supporting pressure of the coal pillar which is on one side of the gob-side remained roadway was deduced.Also, an equation that is used to calculate the width of the balance area in the stress limit state was acquired. Then, an equation that is used to calculate the roof cutting force on one side of the supporting body was obtained. By using FLAC3D, the authors investigated the displacement field and stress field response laws of rock masses around the roadway with different filling body's widths. The results show that with the filling body's width increasing, the supporting ability of the filling body increases.Meanwhile, the rock mass displacement around the roadway and the filling body deformation decrease.The better the filling body's supporting effect is, the higher the roof cutting force will be. When the filling body's width is larger than 3.0 m, its internal bearing ability becomes stable and the filling body's deformation became non-apparent. Finally, analysis shows that the filling body's width should be 2.5 m.Furthermore, the authors conducted field tests in the supply roadway 1204, using high-water materials and acquired expected outcomes.

Study on Filling Cross-Roadway in Fully-Mechanized Coal Faces with High Water-Content Material

A new method using high water content material to mechanically fill cross roadways to form artificial bottom for coal faces was introduced. The reasonable determination of filling range, the optimization of the compounding ratio of high water content material, and the filling technique were discussed in detail. This new method has been spread after industrial testing in Baodian Colliery. Compared with the traditional method, the manual wooden chock method, the new one decreases about 40% of the filling range and cost in dealing every one set of cross roadway in the testing condition.

Creep Property of Solidifying Backfill Body of High-Water Material

On the basis of the creep test of bigh-water materisl solidifying backfill body(abb. HW body), This paper discusses its creep properties- The visco-elasto-plastic model, which shows the creep properties of HW body, is developed, and the creep contitutive equations are deduced. The visco-elastoplastic model is proved by the experiments and practice.

REQUIREMENT OF FLUIDITY OFHIGH WATER CONTENT MATERIALS FOR THE GETWAY-SIDE BACKFILLING TECHNIQUE

Through analyzing the effects of water consumption, diameter of solid particle, and flow vefority on the fluidity of high water content material slurry, the relatinnship among the fluidity, the isotropy of the slurry, and the pumping facilities applied in getway-side backfilling has been found. And the requirment of fluidity of high water content material for the design of getway-side back filling technique is put forward in the paper.

NEW TECHNOLOGY OF ROADSIDE ENTRY SUPPORT IN ADVANCING-MINING BY PUMPING HIGHWATER-CONTENT FAST SETTING-SOLIDIFYING MATERIALS

Roadside entry supporting technology by pumping high water-content fast setting-solidifying materials in advancing-mining was industrially tested in Yangzhuang Coal Mine, Huaibei Coal Mining Administration. Roadside packing parameters were determined according to the properties of high water-content fast setting-solidifying materials, as well as geological and mining conditions. A new roadside packing technological system was designed to use pumping-delivery method to transport the materials. With respect to the special conditions in the advancing mining system, effective temporary support systems were designed and tried. The technical and economic benefits from this new industrial experiment were carefully analyzed and evaluated.

THE RESEARCH OF RHEOLOGICAL PROPERTIES OF STOWING SLURRY WITH HIGH-WATER MATERIALSOLIDIFYING TAILINGS

High-water material, tailings from goldmine and water are mixed into a new slurry.Testing of rheological properties of stowing slurries A and B is made to determine type and rheological parameters of the slurry. The main factors influencing rheological properties of the slurry are analyzed and the rational concentration and empirical resistance calculating formula of pipe line transportation are presented.

Coal and gas outburst prevention using new high water content cement slurry for injection into the coal seam

As coal and gas outburst is one of the most serious mine disasters, it is very important to at least control it if not prevent it from occurring. Injecting cement slurry or grouting into the coal seam can strengthen the seam, increase its rigidity coefficient(f), and reduce the volumetric expansion due to gas energy release.This paper reports the results of laboratory experiments on cement-based high water content slurry having different water-cement ratios(W/C) to be used for coal injection. The results show that as the W/C increases, the mobility of the slurry and its setting time increase. The compressive strength and rupture strength, however, are reduced. Furthermore, high W/C grout shows early strength after 7 days, which can be 80% of its 14-day compressive strength. To achieve rapid setting and early strength, the addition of Na_2SiO_3has proven to give the best result, when the concentration of the additive is 3%. The initial and final setting times are 13 and 21 min shorter than samples without Na_2SiO_3, while the compressive strength is more than double. As a retarder, the initial setting time can be extended to 83 min when tartaric acid of 0.4% concentration is added. Through the orthogonal experiment, the optimum recipe of the new high water content slurry has been determined to be: W/C = 2, tartaric acid = 0.2%, Na_2SiO_3= 3%, and12% bentonite. Reinforcement by injection simulation experiments show that the grouting radius of the new slurry mix is 250 mm when the applied grouting pressure is 60 k Pa, 7-day rupture strength and compressive strength are 5.2 and 6.4 MPa, respectively, and are 37% and 88% higher than ordinary cement grout. It can be concluded that the newly developed slurry mix is more effective than the ordinary mix for reinforcing coal and controlling gas outburst.

Application of the High Molecular Water-keeping Compound Sodium Polyacrylate in Agriculture

The proparties of the high molecular water- absorbing compound sodium polyacrylate(SP) and its application in agriculture are reviewed; and its safety in application is also introduced.

High entropy materials as emerging electrocatalysts for hydrogen production through low-temperature water electrolysis

The production of hydrogen through water electrolysis(WE)from renewable electricity is set to revolutionise the energy sector that is at present heavily dependent on fossil fuels.However,there is still a pressing need to develop advanced electrocatalysts able to show high activity and withstand industrially-relevant operating conditions for a prolonged period of time.In this regard,high entropy materials(HEMs),including high entropy alloys and high entropy oxides,comprising five or more homogeneously distributed metal components,have emerged as a new class of electrocatalysts owing to their unique properties such as low atomic diffusion,structural stability,a wide variety of adsorption energies and multi-component synergy,making them promising catalysts for challenging electrochemical reactions,including those involved in WE.This review begins with a brief overview about WE technologies and a short introduction to HEMs including their synthesis and general physicochemical properties,followed by a nearly exhaustive summary of HEMs catalysts reported so far for the hydrogen evolution reaction,the oxygen evolution reaction and the overall water splitting in both alkaline and acidic conditions.The review concludes with a brief summary and an outlook about the future development of HEM-based catalysts and further research to be done to understand the catalytic mechanism and eventually deploy HEMs in practical water electrolysers.

注水站高压注水泵盘根盒压帽断裂分析

中原油田高压注水泵盘根盒压帽出现多起断裂事故,给安全生产带来较大风险隐患。通过现场基本情况、压帽化学成分、硬度和金相组织的分析,再加上断口的宏观形貌、微观形貌分析等方法,查找压帽发生断裂原因。结果表明,压帽断裂原因一是由于铸造材质疏松,且存在缺陷;二是由于注水泵高压波动对断裂起到了关键性破坏作用,属于“材质因素和力学因素”共同作用导致的断裂。

Al-Sn复合材料的制备及其水反应产氢效率

为提高Al和水的反应活性,采用高能球磨法制备了Al-Sn复合材料,通过SEM、激光粒径分析、XRD等方法表征了Al-Sn复合物的微观结构,研究了Al-Sn复合材料的水反应活性,考察了颗粒粒径、水介质、起始温度、球磨参数变化对Al-Sn复合物水反应活性的影响。实验结果表明,高能球磨法及金属Sn的加入能够大幅提高Al与水反应的活性,制备的Al-Sn复合材料与水反应的氢气产率达83.92%,快速期最大产氢速率为359mL/(min·g)。

面向大电流密度电解水的碳基催化剂研究进展

电解水体系可以在温和条件下制备氢气。得益于高比表面积、高电子传输性和原料丰富等优点,碳基电催化剂备受关注。商业用电解水装置需要在较低过电位下实现较大交换电流,进而实现氢气的持续快速生产。然而当前实验室研究的重心大多放在小电流服役工况,对于大电流工况下的系列问题关注较少。研究表明,电解水体系在不同电流密度下表现出的问题差异较大,其影响因素包括气泡、电催化剂局域微环境和电极稳定性等。本综述,首先对碳基电解水催化剂的发展现状进行了总结,大电流模式下暴露出的问题与挑战进行了讨论,并提出可能有效的解决方法,以实现能满足大电流密度要求的高活性高稳定性碳基电催化剂的研发。

基于低标硫铝酸盐水泥熟料的高水材料物理力学性能及应用

为解决高水材料充填成本高、物理力学性能差等问题,选用低标硫铝酸盐水泥熟料为主要原料,通过物理试验探究了低标硫铝酸盐水泥熟料高水材料在不同外加剂剂量、水灰比、水温下的物理力学性能,并通过工艺性试验测试了实际应用效果。研究结果表明:(1)不同条件下高水材料物理力学性能不同的主要原因在于其钙矾石的生成速率及生成量受到影响;(2)以低标型硫铝酸盐水泥熟料作为高水材料原料时,使用一定量外加剂能够改善其样貌并显著提升其强度;(3)降低水灰比能够显著提升高水材料的早期强度及峰值强度,且每提高0.1的水灰比,平均各龄期强度下降约11%;(4)水温对于高水材料初凝时间的影响高于终凝时间,对早期强度起促进作用,水温每上升2℃, 1d强度增加约6.8%;(5)影响高水材料强度的各项因素排序为:外加剂>水灰比>水温;(6)现场应用低标型硫铝酸盐水泥熟料高水材料后,巷道变形量较小,取得较好的留巷效果。

基于双粘型防水材料的高水压隧道新型堵水限排方案及设计方法

为解决高水压隧道渗漏水病害并减少治理成本,基于双粘型喷膜防水材料,提出一种由注浆加固圈、双粘型防排水系统和防水衬砌3部分组成的新型堵水限排方案。依托数值计算方法,揭示该方案的水压分布特征并论证其有效性,进而分析注浆圈及排水板各参数对隧道涌水量及衬砌水压力的影响规律;在此基础上,提出高水压隧道多级控制型限排方案的设计方法。研究结果表明:1)新型堵水限排方案可通过调节注浆圈及排水板参数使二次衬砌水压力降低到可接受范围;2)与传统高水压隧道主要依靠注浆圈来调节渗水量及衬砌水压力不同,新型限排方案可采用注浆圈+排水板多级调控方法,方案设计更加灵活,其中注浆圈占主导作用;3)注浆圈对降低隧道渗水量及衬砌外水压力均有利,其中渗透系数参数最为重要;4)仅当注浆圈渗透系数得到保障时,才存在合理的排水板间距使衬砌水压力与隧道渗水量控制在合理范围内。

居民小区高品质饮用水入户建设与改造策略探讨

为增强人民群众获得感、幸福感与安全感,供水行业应立足新发展阶段、贯彻新发展理念、构建新发展格局、推动高质量发展,全面提升城市供水安全保障能力,实现饮用水的高品质供给。在水源、水厂、管网等环节提升改造的同时,二次供水“最后一公里”环节成为目前高品质饮用水建设的重点与焦点。目前老旧小区实现高品质饮用水入户的工程建设与改造还缺少相关成熟经验,也没有统一的实施路径。文章以问题为导向,结合调查分析与试验研究,分析了现状住宅小区二次供水设施存在的主要问题,提出了供水模式优化、涉水材质选择、标准泵房建设、系统水龄控制、智能监控管理等二次供水入户工程改造实施策略与技术要求,供相关工程建设参考。

复杂富水地层无机固水材料注浆堵水应用研究

马钢矿业姑山矿业公司采用的常规单液水泥注浆封堵复杂富水地层导水通道,存在可注性及浆液扩散效果差等问题,对此,姑山矿业公司进行了高效无机固水材料替代水泥注浆堵水试验。结果表明:高效无机固水材料注入会形成钙矾石,其注浆材料成本为156.98~228.81元/m^(3),注浆结石体材料费用仅为常规单液水泥浆的一半;相对于单液水泥浆,高效无机固水材料浆液具有可输送性和可注性强、固结速度快、固结后体积收缩率小、生产成本低等优点;该高效无机固水材料具有良好的推广应用前景。

“三硬”薄煤层沿空留巷围岩破坏特征及控制技术研究

为解决薄煤层沿空留巷应力条件复杂、留巷难度大以及巷道围岩长时稳定性的难题,以陕西汇森煤业凉水井煤矿4301工作面为研究对象,采用理论分析、数值模拟、工程实践等方法,对浅埋“三硬”薄煤层沿空留巷围岩破坏特征及控制对策进行研究,分析巷旁支护体结构参数对于巷道稳定性的影响。结果表明:给顶板提供充足的支护强度以及合适的可缩量,是巷旁充填体整体稳定的前提;高水充填材料单轴加压下的力学行为可分为“均匀压密、弹性变形、动态失稳、劣化破坏”4个阶段;在充填体宽度增加过程中,最大应力表现为先增后减再增的趋势,在充填体1.6 m宽时出现稳定承载应力核;理论计算的切顶最佳高度为10.7 m。工程实践表明,工作面后方60 m范围无大变形和明显应力集中,围岩整体控制效果良好、结构稳定,留巷效果达到设计要求。

巷旁充填留巷顶板结构分析与围岩控制技术

为研究沿空留巷顶板结构特征及其支护技术,基于弹性力学薄板理论,建立了沿空留巷顶板悬板结构模型,推演了两种边界条件下悬板主应力表达式,构建了应力比例系数作为薄板破坏判据,研发了沿空留巷巷内顶板斜拉锚索加强支护、巷旁超高水材料复合支护技术。研究结果表明:锚网索支护沿空留巷过程中实施超前预裂切顶,顶板可形成悬板结构,该结构随上覆顶板运动可形成一对边简支一对边自由和一对边固支简支一对边自由两种悬板形式;在矿山压力作用下两种悬板破坏部位不同,可以此作为布置顶板斜拉锚索的依据;顶板斜拉锚索对悬板起悬吊和水平挤压作用。现场试验结果证明了理论分析的可靠性。