羟基磷灰石料浆流变性及注浆成型工艺的研究

选用聚乙二醇、聚乙烯醇、聚丙烯酸、甲基纤维素等为分散剂,研究其用量对羟基磷灰石（HA）陶瓷料浆流变性能和电动特性的影响。结果表明：料浆都呈现出剪切变稀的假塑性流体特性,其中添加0.5%甲基纤维素的陶瓷料浆具有较高的Zeta电位值(70 mV),同时具有优良的流变性和触变性。并对不同分散剂稳定料浆改善其流变性能的可能机理做了初步的探讨。在此基础上,制得了高流变性和触变性的HA料浆,研究了双氧水发泡成型工艺所得的粗坯体及高温烧结体的显微结构。通过该工艺所获得的HA样品孔壁较薄,孔径分布均匀。     

Spatiotemporal evolution of thermo-hydro-mechanical-chemical processes in cemented paste backfill under interfacial loadingOA

Cemented paste backfill(CPB) and rock interface interaction causes the formation of an interfacial loading and affects the thermal, hydraulic, mechanical, and chemical processes in bulk CPB and thus its in-situ behavior. In this study, a new meter-sized column model is developed to systematically investigate the multiphysics processes in CPB under interfacial loading. The obtained results discover that for the mechanical process, the interfacial loading leads to a reduced settlement and a weaken...     

Correlative mechanism of hydraulic-mechanical property in cemented paste backfill

Hydraulic characteristic is a good indication of binder hydration, which determines the strength development of cemented paste backfill (CPB). Therefore, the hydraulic characteristic should be communicated with the mechanical property to provide an advanced knowledge that can help mine workers make a rational strategy and reduce the mining cycle. An experimental program was performed to obtain the hydraulic (monitored by suction and volumetric water content) and mechanical properties (unconfined compressive strength (UCS) test) of CPB at the 28 days curing age. According to the monitoring and testing results, the relationships between the hydration reaction rate and volumetric water content (VWC), suction and VWC, suction and UCS were established. The hydration degree showed a liner rise as the VWC decreased. Curves of the VWC and UCS were featured with a nonlinear reduction and nonlinear growth (both are exponential functions) as the suction rising, respectively. These established relationships validated the strong correlative mechanism of hydraulic and mechanics behavior for CPB. Also, the results of the present research indicated that the hydraulic characteristics and mechanical property were strongly coupled. These correlations and couplings will be of great importance to understand the hardening process of CPB and bring to a safe CPB field operation.     

基于NMR技术的孔隙结构与充填体强度关联机制

充填料浆凝固后形成的充填体中含有大量的孔隙,孔隙对充填体力学性能的影响尚不明确。为探究充填体内孔隙结构与充填体单轴抗压强度(Uniaxial compressive strength, UCS)的关联机制,利用十二烷基硫酸钠(Sodium dodecyl sulfate, SDS)调节充填体内的孔隙含量,采用低场核磁共振技术(Nuclear Magnetic Resonance, NMR)测试充填体内部孔隙的横向弛豫时间,利用压力机测试充填体的UCS,利用扫描电镜(Scanning electron microscope, SEM)获取充填体破坏面孔隙结构的微观图像,对孔隙的孔径分布进行了分析,对孔径的分形特征进行了研究,结果表明：充填体内孔隙总量随着养护龄期的增加逐渐降低,且SDS掺量越高,样品在14d与28d时的孔隙总量越接近；多害孔隙的占比随着养护龄期的增加明显降低,且与样品的UCS呈负相关,无害孔隙、低害孔隙、有害孔隙的占比在各龄期间变化较小；SDS掺量为所用水泥质量的2‰时对样品的UCS最有益；孔径在5nm-130nm区间的孔隙数量具有较为明显的分形特征,而孔径不在该区间的孔隙数量不具有分形特征；水泥水化反应产物呈簇状,簇状产物因生长、发育、延伸而挤占了孔隙空间是孔隙总量、多害孔隙数量随养护龄期增加不断降低的微观原因。研究结果可以为更全面的理解充填体强度提供理论支撑。     

磁铁矿对超高密度水泥浆体系性能的影响

针对钻探深井超深井过程中的高温高压固井问题,研制一套抗高温超高密度水泥浆体系。该水泥浆体系由磁铁矿粉、降失水剂FS-23L、分散剂SXY-2、缓凝剂HX-31L配制而成。通过对超高密度水泥浆流变性、流动度、沉降稳定性和抗压强度等的评价,得到磁铁矿加重剂的优选加量范围,以及适应循环温度150℃的综合性能良好的水泥浆配方。     

基于BP神经网络的充填料浆流变参数预测分析

为了合理分析充填料浆在长距离管道中的输送阻力,基于流变参数对输配管网设计的重要性,在全面评估不同因素对流变性能影响的程度后,采用BP神经网络原理,建立起干料中水泥含量X1、料浆浓度X2、料浆坍落度X3、料浆容重X4对流变参数(屈服应力Y1、粘性系数Y2)影响的函数模型.此BP网络为4-Hn-2结构,隐层和输出层分别用tansig、purelin函数传递,利用Levenberg-Marquardt优化算法trainlm训练网格.计算结果表明:该模型在预测充填料浆屈服应力Y1和粘性系数Y2中适应性较强,误差也在可控范围之内,可为充填管网布设及输配系统沿程阻力分析提供可靠依据.     

油基油水煤浆的流变性质研究

研究了一系列稳定的油基油水煤浆的流变性质,探讨了煤种以及煤浆中煤,水,油三相比例对煤浆流变性质的影响规律,并对流变曲线进行了回归分析。结果表明,煤浆属于屈服－假塑性流体,油基油水煤浆的流变性能好,粘度低,其内部存在着由煤颗粒和水滴及油滴共同的构建而成的立体网状结构,对于制浆研究具有重要的指导意义。     

低需水的新拌水泥浆体流变性研究

在对水泥浆体流变模型和流变性能影响因素分析的基础上，研究了外加剂掺量、SO3含量、矿渣掺量等对新拌水泥浆流变性能的影响。用旋转粘度计对新拌水泥浆进行了动态检测，低需水量水泥的新拌水泥浆具有良好的流变性能，同时它的流变模型符合宾汉姆流变模型。     

Rheological behaviors of fresh cement pastes with polycarboxylate superplasticizer

The rheologicalbehaviors of fresh cement paste with polycarboxylate superplasticizer were systematically investigated.Influentialfactors including superplasticizer to cement ratio(Sp/C),water to cement ratio(w/c),temperature,and time were discussed.Fresh cement pastes with Sp/Cs in the range of 0 to 2.0% and varied W/Cs from 0.25 to 0.5 were prepared and tested at 0,20 and 40 °C,respectively.Flowability and rheologicaltests on cement pastes were conducted to characterize the development of the rheologicalbehavior of fresh cement pastes over time.The exprimentalresults indicate that the initialflowability and flowability retention over shelf time increase with the growth in superplasticizer dosage due to the plasticizing effect and retardation effect of superplasticizer.Higher temperature usually leads to a sharper drop in initialflowability and flowability retention.However,for the cement paste with high Sp/C or w/c,the flowability is slightly affected by temperature.Yield stress and plastic viscosity show similar variation trends to the flowability under the abovementioned influentialfactors at low Sp/C.In the case of high Sp/C,yield stress and plastic viscosity start to decline over shelf time and the decreasing rate descends at elevated temperature.Moreover,two equations to roughly predict yield stress and plastic viscosity of the fresh cement pastes incorporating Sp/C,w/c,temperature and time are developed on the basis of the existing models,in which experimentalconstants can be extracted from a database created by the rheologicaltest results.     

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.     

低挥发分煤的成浆特性和水煤浆流变特性

为了研究低挥发份煤的制备水煤浆的性能,利用黏度计对水煤浆的温度、表观黏度、剪切应力以及剪切速率等参数进行测量和计算,分析加入5种不同添加剂后低挥发分煤水煤浆的成浆特性、最大成浆质量分数、温升特性、流变特性等性能,发现水煤浆的黏度随着质量分数的增加而升高;在黏度为1 000 mPa·s时,加入不同添加剂的低挥发分水煤浆的最大成浆质量分数均在70%左右;加入不同添加剂对水煤浆的温升性能有不同影响,水煤浆的黏度随着温度的升高而逐渐降低,但是当水煤浆质量分数较高时,高温可能导致部分添加剂失效;随着剪切速率的增加,水煤浆的黏度逐渐降低,为假塑性流体.结果表明低挥发份煤具有很好的性能用于制备高浓度水煤浆.     

基于水泥净浆流变性的振动-剪切等效理论

为了分析振动条件下水泥净浆的流变特性,解释水泥净浆流变性模型的转化机制,提出适用于振动条件下水泥净浆流变性分析的振动-剪切等效理论. 根据修正HI理论和回转黏度仪径向分层算法,计算振动条件下回转黏度仪内水泥净浆流场的剪切速率,将振动台正弦振动过程转化为对水泥净浆的剪切过程. 采用自制回转黏度仪,开展20 Hz振动频率下的HI参数标定试验和30 Hz振动频率下的水泥净浆黏度试验. 结果表明,HI参数标定结果与数值计算结果之间的误差约为7%,水泥净浆的试验黏度与数值计算的黏度之间的误差为8%并趋于收敛状态. 增大振动频率,水泥净浆的黏度逐渐减小并达到峰值,流变性模型逐渐由Bingham模型转变为Hershel-Bulkley模型,最后转变为Power-Law模型.     

纤维增强膏体充填材料的宏细观试验

为了提高膏体充填体的稳定性,在膏体充填材料中加入纤维以改善其脆性.采用宏细观试验方法研究了聚丙烯纤维增强膏体充填材料的破坏行为.从宏观上,通过一系列单轴压缩试验定量研究了纤维掺量对膏体充填材料力学性能影响.采用X射线CT多层切片扫描技术分析了纤维对膏体充填体试件细观结构的影响.研究结果表明:水泥掺量为10%时,纤维使膏体充填材料的峰值强度略有增加,纤维可大幅度提高其韧度和峰值强度点的应变;纤维能阻止试件中裂缝的扩展和延伸,使裂缝细化、分散,进而使试件在破坏前可形成更大体积的裂缝,这些裂缝在形成过程中可吸收更多的能量,从而提高膏体充填材料的韧性.     

新型油井水泥促凝剂WSA-1室内研究

在导管或表层段低温固井中,水泥水化速度慢,候凝时间长,油井水泥石早期强度发展缓慢,影响固井质量和作业安全。针对目前国内油田低温浅层固井可供选择的油井水泥促凝剂种类少、某些油井水泥促凝剂促凝和早强效果不佳以及对水泥浆流变性影响较大等问题,通过室内实验研制了一种新型复合促凝剂WSA-1。对加有促凝剂WSA-1的水泥浆进行了系统的性能评价。结果表明:促凝剂WSA-1能加速油井水泥的水化过程,缩短水泥浆的稠化时间,显著提高水泥石的早期强度,当m(WSA-1)∶m(水泥干灰)=3%时,水泥浆稠化时间可缩短50%以上,水泥石6h强度从3.2MPa增强到11.3MPa,24h抗压强度从24.3MPa增强到46.1MPa,完全满足其评价标准的相关要求,且对水泥浆的初始稠度和流变参数基本无影响,是一种性能优异的、可用于低温浅层油气井固井水泥浆体系的复合促凝剂。     

宁波软土流变试验及经验模型

为了研究宁波软土的流变特性及经验模型,进行一维固结流变试验和三轴排水流变试验,并采用西原模型拟合模型参数.试验对比分析表明,固结试验的侧限作用会阻碍试样流变的发展,应力-应变等时曲线偏向应力轴,而三轴流变试验试样的流变能够得到充分地发展,应力-应变等时曲线偏向应变轴,能够更好地体现软黏土的流变性状.将一维西原模型应力-应变关系扩展到三维,采用修正剑桥模型屈服函数描述材料的塑性屈服.推导荷载恒定时土样的轴向应变计算公式,根据三轴排水流变试验结果进行曲线拟合,确定西原模型参数.结果表明,该模型能够较好地符合宁波软土的流变规律.     

Rheological properties of self-compacting concrete paste containing chemical admixtures

Self-compacting concrete (SCC) was used for the filling layer of CRTSIII plate ballastless track, which needs excellent workability. The rheological properties of SCC cement paste containing chemical admixtures (CA) such as polycarboxylate-based superplasticizer (PCE), air-entraining agent (AE) and defoamer (DF) were investigated using a Brookfield R/S SST2000 soft solid tester with a vane geometry spindle. The cementitious materials were designed as one, two and, three components systems by addition of ordinary portland cement (OPC) with these chemical admixtures. The rheological properties of one-component system (PCE paste) were improved with increasing the content of PCE. For two components systems of PCE-AE and PCE-DF, yield stress and plastic viscosity reduced firstly and increased afterward with the increasing of AE content. And the plastic viscosity reached the optimum when the content of AE is 0.004wt%. In general, the trend of yield stress and plastic viscosity decreased with the increasing of the DF content. For three components systems, PCE-AE-DF systems, the rheological properties were improved compared with the sample with AE or DF, which attributed to mixes of the active components mentioned above (CA) which could have a synergetic effect.     

The mechanical properties of coastal soil treated with cement

The influences of cement type, cement content, and curing time on the unconfined compression strength （UCS） of soil-cement were investigated. The influence of groundwater on UCS of soil- cement was also studied. The experimental results indicate that the soil treated with high grade cement presents a higher UCS. Additionally, the UCS of soil-cement presents linearly increased with the cement content. A logarithm correlation between UCS and curing time presents to forecast the strength development. Compared with the UCS of samples immersed in distilled water, those immersed in groundwater oresent a hizher value.     

Cemented backfill technology based on phosphorous gypsum

Physical-chemical properties of phosphorous gypsum, proportion and cemented mechanism of slurry with gypsum as aggregate were studied to remove the harms of gypsum pile, combining with difficult problems of excessive mined-out gobs, enormous ore body under roadway and low recovery ratio of Yongshaba Mine, Kaiyang Phosphor Mine Group, Guizhou Province, China. An appropriate backfill system and craftwork were designed, using shattering milling method to crush gypsum, double-axles mixing and strong activation mixing way to mix slurry, cemented slurry and mullock backfill alternately process. The results show that gypsum is fit for backfilling afterwards by adding fly ash, though it is not an ideal aggregate for fine granule and coagulate retardation. The suggested dosage (the mass ratio of cement to fly ash to gypsum) is 1:1:6–1:1:8 with mass fraction of solid materials 60%–63%. Slurry is transported in suspend state with non-plastic strength, and then in concretion state after backfilling. The application to mine shows the technology is feasible, and gypsum utilization ratio is up to 100%. Transportation and backfill effect is very good for paste-like slurry and drenching cemented slurry into mullock, and the compressive strength and recovery ratio are 2.0 MPa and 82.6%, respectively, with the maximum subsidence of surface only 1.307 mm. Furthermore, the investment of system is about 7×10⁶ yuan (RMB), only 1/10 of that of traditional paste backfill system. Foundation item: Project (2006BAB02A03) supported by the National Key Technology Research and Development Program; Project (08MX16) supported by Mittal Scientific and Technological Innovation Projects of Central South University during 2008     

葡萄花黑帝庙浅层含蜡原油流变性研究

原油含蜡会导致地下原油流动的复杂性,原油在管道运输过程中会堵塞管道.葡萄花黑帝庙浅层油藏是典型的低温含蜡油藏,原油在原始地层温度下已经失去流动性,从原油流变性的角度研究这类油藏的开发,分析原油随温度及剪切速率变化的物性特点,对原油开发方案的编制、原油的集输和分析地下原油渗流机理等提供参考.     

Effects of stress conditions on rheological properties of granular soil in large triaxial rheology laboratory tests

In order to study the rheological properties of red stone granular soil,a series of rheological experiments were executed on large tri-axial rheological apparatus.Under 100,200 and 300 kPa confining stress conditions,the rheological tests were carried out.These experiment results showed that the stress conditions,especially the stress level were the critical influencing factors of the rheological deformation properties.Under the low stress level(S=0.1),the granular soil showed the elastic properties,and there was no obvious rheological deformation.Under the middle stress level(0.20.8) creep curves showed the non-linear viscous plastic rheological properties.Especially,under the stress level of S=1.0,the accelerated rheological phase of creep curves occurred at early time with a trend of failure.The stress level had obvious effects on the final rheological deformation of the soil sample,and the final rheological deformation increments nonlinearly increased with stress level.The final rheological deformation increment and step was little under low stress level,while it became large under high stress level,which showed the nonlinearly rheological properties of the granular soil.The confining pressure also had direct effects on final rheological deformation,and the final rheological deformation linearly increased with confining pressure increments.