Effects of Crops, Soil Types and Irrigation Methods on Digestion Capacity of Biogas Slurry

In the research, pot experiment and field testing were conducted to study the effect of different crops, soil types, and irrigation modes on biogas slurry diges- tions. The results showed that when silage maize, sweet sorghum and Chinese cabbage were planted in purple soils, the quantities of digested biogas slurry were of 57, 157.5, and 34.5 t/hm2, respectively, while the quantities of digested biogas slurry were 70.5, 157.5 and 40.5 t/hm2 in yellow soils. Besides, the digested biogas slurries reached 36 and 27 t/hm2 as per flood irrigation and sprinkling irrigation when Chinese cabbages were planted in yellow soils. The research indicated crop variety, soil type, and irrigation method all have effects on farmland digestion of biogas slurry.

Effects of Storage Methods and Time on Content of Nutrients in Biogas Slurry of Straw

To study the effects of different storage methods and time on content of nutrients in biogas slurry of straw, two storage methods were carried out on biogas slurry between open storage and airtight storage conditions at normal atmospheric temperature. The contents of N, P, K, and organic matter in biogas slurry of straw were determined in different storage times. The results showed that： during the pro-cess of biogas slurry storage, little change occurred in the content of the organic matter while the total content of N, P, K significantly declined; up to 50 days, the total content of N, P, K reduced to nearly 80%-90%. Because the contents of N, P, K in biogas slurry reduced less in airtight storage conditions so that a better re-sult was found on airtight storage methods than open storage methods in fertilizer field of biogas slurry of straw.

A grouting simulation method for quick-setting slurry in karst conduit:The sequential flow and solidification method

It is difficult to temporally and spatially track and characterize the slurry viscosity in flowing water during grouting simulation.In this study,a sequential flow and solidification(SFS)method considering the spatial-temporal evolution of slurry viscosity in flowing water in karst conduit is proposed.First,a time-dependent model for the threshold function of slurry viscosity is established.During the grouting process,the spatial-temporal evolution of slurry viscosity is revealed by tracking the diffusion behavior of the slurry injected at different times.This method is capable of describing the gradual solidification process of the slurry during grouting.Furthermore,a physical model of grouting in a karst conduit is developed.Second,the effectiveness of the SFS method in grouting simulation is verified by the experiment of grouting conduit in flowing water.The SFS method enables real-time monitoring of fluid velocity and pressure during grouting in flowing water and provides a feasible calculation method for revealing the grouting plugging mechanism in complex karst conduits at different engineering scales.In addition,it can be used to guide the design of grouting tests in flowing water,improve cost efficiency,and provide theoretical basis for optimizing grouting design and slurry selection.

Computational modeling of free-surface slurry flow problems using particle simulation method

The particle simulation method is used to solve free-surface slurry flow problems that may be encountered in several scientific and engineering fields.The main idea behind the use of the particle simulation method is to treat granular or other materials as an assembly of many particles.Compared with the continuum-mechanics-based numerical methods such as the finite element and finite volume methods,the movement of each particle is accurately described in the particle simulation method so that the free surface of a slurry flow problem can be automatically obtained.The major advantage of using the particle simulation method is that only a simple numerical algorithm is needed to solve the governing equation of a particle simulation system.For the purpose of illustrating how to use the particle simulation method to solve free-surface flow problems,three examples involving slurry flow on three different types of river beds have been considered.The related particle simulation results obtained from these three examples have demonstrated that:1) The particle simulation method is a promising and useful method for solving free-surface flow problems encountered in both the scientific and engineering fields;2) The shape and irregular roughness of a river bed can have a significant effect on the free surface morphologies of slurry flow when it passes through the river bed.

Improvements of marine clay slurries using chemicale-physical combined method(CPCM)

In this paper, the effectiveness, applicability and validity of chemicalephysical combined methods（CPCMs） for treatment of marine clay （MC） slurries were evaluated. The method CPCM1 combineschemical stabilization and vacuum preloading （VP）, while CPCM2 is similar to CPCM1 but includes boththe application of surcharge and use of geo-bags to provide confinement during surcharge preloading.The key advantage of CPCM2 using geo-bags is that the surcharge can be immediately applied on thechemically stabilized slurries. Two types of geo-bags were investigated under simulated land filling anddyke conditions, respectively. The test results show that the shear strength （cu） of treated slurry byCPCM2 is generally much higher than that by CPCM1. Besides, the use of CPCM2 can significantly reducethe treatment time due to the short drainage paths created by geo-bags. Overall, CPCM2 allows fasterconsolidation and higher preloading that help to achieve higher mechanical properties of the stabilizedslurry. There are consistent relationships between cU and water content of slurries treated by CPCM2.Several important observations were also made based on comparisons of experimental data. 2015 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting byElsevier B.V. All rights reserved.

Fluidity Influencing Factor Analysis and Ratio Optimization of New Filling Slurry Based on the Response Surface Method

The filling mining method is important in realizing the green mining of mineral resources.Aiming at the problems of land resource occupation,environmental pollution,and rational utilization of coal-based solid wastes such as coal gangue,fly ash,and desulfurization gypsum,a new paste filling material was developed with coal gangue,fly ash,and desulfurization gypsum as raw materials.The microstructure of the raw materials was analyzed by XRD and SEM.Combined with the Box-Behnken experimental design,the effect of each component on the fluidity of the filling slurry was analyzed through the response surface analysis.The significance of each component on its bleeding and fluidity was determined,and the optimal ratio of the filling slurry was obtained.Experimental results show that the microcosmic morphology of coal gangue,desulfurization gypsum,and gasification slag presents an irregular block and rough particle surface;the microcosmic morphology of fly ash and bottom slag presents first out spherical or quasi spherical particles.Moreover,obvious sintering traces exist on the surface of the bottom slag.The main crystal mineral of coal gangue and fly ash is SiO_(2),the desulfurization gypsum is composed of Ca(SO_(4))(H_(2)O)and Ca(CO_(3))crystal minerals,the gasification slag is composed of carbon and nitrogen compounds,and the main crystal mineral components in the bottom slag sample are SiO_(2) and Al_(x)Si_(y)O_(z) compounds.The order of significance of each key factor on slurry fluidity is as follows:C(desulfurization gypsum)>D(gasification slag and bottom slag 1:1)>A(coal gangue)>B(fly ash).The order of the significance of each key factor on slurry bleeding is as follows:B(fly ash)>C(desulfurization gypsum)>D(gasification slag and bottom slag 1:1)>A(coal gangue).Considering the material preparation,field application,and other conditions,the mass percentage of each factor content of the new paste filling material is as follows:49.5%coal gangue,8.3%fly ash,4.1%desulfurization gypsum,6.2%gasification slag,and 6.2%bottom slag.

The Microstructure and Oxidation Resistance of The Microstructure and Oxidation Resistance of Slurry Method on Rene 80 Superalloy

The slurry method is one of the oldest techniques of deposition of aluminide coating on the nickel superalloy, titanium alloys and steel. It is characterized by relatively low costs of its realisation and necessary equipment. This method en-ables a simple modification of chemical composition of the coating through addition of different powders. The author showed study on the possibility of modification of the Al-Si slurry chemical composition used for aluminide coating deposition by addition of MeCrAlY powder. The slurry was deposited by immersion than the diffusion treatment at 950℃ for two hours was applied. The thickness of obtained coatings was in the range of 30 - 65 μm.

糯米浆灰土无侧限压缩和三轴剪切离散元分析

糯米浆灰土是一种常见的遗址保护建筑材料,为研究糯米浆灰土压缩加载过程中的糯米-石灰胶结破坏和接触组构演化情况,采用离散单元法开展了糯米浆灰土无侧限压缩和三轴剪切离散元模拟。首先基于软胶结模型考虑糯米浆-石灰的强度特征,制备了糯米浆灰土离散元试样;然后通过参数敏感性分析为试样赋予合理的接触模型等效模量和胶结强度参数,最后对试样开展无侧限和三轴压缩模拟。结果表明:离散元模拟能再现糯米浆灰土加载试验的主要特征;加载过程中胶结破坏数量先缓后快增加,最终趋于平缓,胶结破坏呈现一定的聚集效应;无侧限压缩下胶结接触主要发生拉伸破坏,随着围压增加,剪切破坏接触数量增加;试样偏组构快速增加段为胶结破坏诱发。

基于RSM的超细水泥注浆材料配比及性能优化模型

注浆堵水技术已成为水害措施防范向工程治理不可缺少的技术之一,超细材料的研究也成为了目前注浆材料发展的新方向。为了解决矿井水害注浆治理工程中注浆材料优选和配比优化问题,采用单因素试验与响应曲面法(RSM)相结合的方法进行超细水泥注浆材料优化配比研究。首先通过单因素试验对不同水灰比、硅灰(SF)掺量及高效聚羧酸减水剂(PCS)掺量条件下浆液黏度、泌水率及7 d单轴抗压强度进行分析,以确定RSM最佳基准水平,其次构建以浆液黏度、泌水率及7 d单轴抗压强度为响应目标的二次多项式预测模型,结合方差、残差及响应曲面分析各响应变量对响应目标的影响规律,确定注浆材料最优配比。通过单因素试验结果对比分析,发现最优水灰比、SF掺量及PCS掺量分别为1∶1、35%及0.3%。通过RSM研究发现,浆液黏度、泌水率及7 d单轴抗压强度不仅受单一因素影响,且存在多因素交互作用。根据建立的二次多项式响应面回归预测模型可知,当水灰比、SF掺量及PCS掺量分别为0.7∶1、38%及0.2%时,注浆材料性能最优,其回归模拟预测浆液黏度、泌水率及7 d单轴抗压强度分别为210.82 mPa·s、1.0%及12.22 MPa。通过室内试验,其结果与预测模型结果吻合度较高,进一步验证了模型的可靠性,证明了该模型能够用于注浆材料优化配比设计研究。

基于离散元法的盾尾同步注浆扩散及参数优化研究

为观察盾构施工中同步注浆扩散规律,并提出注浆参数调控手段,以滨海砂土地层为目标,设计并开展盾尾同步注浆模型试验,获得隧道外侧不同位置浆液扩散规律。在借助试验结果标定离散元模型中各颗粒间接触参数的基础上,建立盾尾同步注浆连续-离散元耦合模型,模拟浆液填充渗透过程,对照试验结果分析导致注浆层厚度差异的主要原因,进而通过调整注浆参数优化浆液填充效果。结果表明:离散元仿真模型中的颗粒运移特性能够有效展示浆液在盾尾间隙及周边土层中的填充、渗透现象;受流动性影响,浆液较易在注浆孔口聚集,而若注浆压力不足,将导致距离注浆孔较远的隧道上、下侧浆液层均匀性不良,通过调整不同部位注浆孔压力配比关系,可有效改善填充效果;注浆层受土层压力影响,隧道上方厚度相对下侧较薄,而侧面浆液在自身重力作用下向下沉积,呈上薄下厚分布。

二氧化硅抛光液中金属杂质的检测方法

采用高分辨电感耦合等离子质谱仪检测二氧化硅抛光液中金属杂质元素,通过调节元素分辨力,选择适合的同位素进行检测,可有效解决质谱干扰问题。采用标准加入法稀释样品检测金属杂质含量的方法,10μg/kg加标回收率为81.17%~111.79%,可以实现对二氧化硅抛光液中多金属杂质的快速分析。

国际水电项目GIN参数设计方法研究

在Lombardi博士的GIN理论基础上,结合世界大坝委员会的坝基设计公报及以往国际水电站工程采用GIN灌浆取得的经验,依托科特迪瓦波波里水电站土石坝帷幕灌浆的实践,阐述了基于坝基岩石质量与压水试验成果的GIN设计值的取值方法,提出了P_(max)、V_(max)值设计时需要考虑的两种边界条件,并通过理论公式计算及实践经验提出了浆液扩散半径的安全保证系数。

改性木质素磺酸钠在煤沥青水浆中的性能研究

为提高煤沥青利用率,以LS(木质素磺酸钠)为主要原料,经磺甲基化和缩合反应后合成MLS(改性木质素磺酸钠)分散剂,用于制备煤沥青水浆。采用FTIR(红外光谱)、XRD(X射线衍射)和表面张力分析了MLS的结构及性质,采用响应曲面法考察其最佳制备条件,并研究浆体的分散稳定性。结果表明MLS分散剂的最佳制备条件为:磺甲基化试剂质量分数12%,甲醛质量分数18%,尿素质量分数10%,反应温度80℃,反应时间4 h。当MLS质量分数为0.5%时,最大制浆质量分数达到54.83%,而LS的最大制浆质量分数仅为51.44%。且MLS分散剂制备的浆体,属于屈服假塑性流体,符合Herschel-Bulkley模型,屈服应力较小。静置5 d后,LS和MLS制备的浆体析水率分别为3.45%和2.30%,说明MLS的降黏增稳能力较强,利于提高煤沥青水浆的工业应用。

瓷砖用高稳定性陶瓷喷墨浆料的制备及性能研究

水性喷墨打印技术是目前构筑瓷砖表面釉层的新型方式,所使用的水性陶瓷浆料的稳定性对其喷墨打印性能起到了至关重要的作用。以市购的陶瓷喷墨原浆为原料,采用分散法制备了系列瓷砖表面喷墨打印改性陶瓷喷墨浆料,重点考察了分散剂种类、含量等因素对陶瓷喷墨浆料长期悬浮稳定性、粘度、表面张力的影响规律,结果表明:相比于陶瓷喷墨原浆,添加3 wt%PAAS的陶瓷喷墨浆料具有良好的粘度(52.42 mPa.s)和表面张力(68.3m N/m),满足喷墨打印使用要求。而且,PAAS改性浆料在30天静置沉降过程中未出现硬质沉淀的不良特征,表现出更高的悬浮稳定性,这归因于分散剂PAAS与原浆表面形成双层电荷,同时依靠长分子链,起到静电位阻稳定作用。研究的相关结果对于开发新型的瓷砖表面用的高稳定性陶瓷喷墨浆料具有指导意义。

水泥水化影响水合物层稳定性定量评价装置及影响程度的评测

针对海洋深水水合物层在固井过程水泥水化放热对水合物分解量的影响缺乏量化评价装置及方法的问题,充分考虑固井过程中水泥浆体系与水合物层的接触方式,建立了一套模拟水合物层固井的水合物稳定性评价实验装置,该装置实现了低温高压下水合物的生成、带压条件下水泥浆与水合物层接触的流动泵入,直观地测试了与水合物层直接接触下的水泥浆水化放热对地层温度、压力的影响。根据设计的实验装置,通过对水合物饱和度、水合物分解气量的推导计算,建立了一套水合物模拟地层的制作方法,并建立了水泥浆水化影响水合物层稳定性评价方法。根据南海地区浅层地质条件建立了模拟水合物地层,泵入G级油井水泥净浆、低密水泥浆体系和低热水泥浆体系等3组水泥浆体系,得出单位体积油井水泥候凝过程中分解水合物的气体的量分别为0.7356、0.1091和0.0649 mol/L,且评测表明,低热水泥浆体系能够大幅度缩短固井候凝的等待时间。该研究为油气固井过程中对浅层水合物的影响提供了直观测试方法,也证明了海洋深水水合物地层中使用低热水泥浆体系的必要性。

基于卡曼滤波的矿浆浓度计设计

设计了一种基于卡曼滤波的γ射线浓度计。通过分析射线浓度计的测量原理,建立了射线强度与矿浆浓度的关系式;利用卡曼滤波对射线强度进行最优估计,以抑制测量结果的扰动;最后通过最小二乘法分段拟合计算对应的浓度。结果表明,该浓度计测量及时、准确,最大误差0.328个百分点,均方根误差0.194个百分点,测量精度得到有效提高。

黏结剂种类对加热不燃烧型烟草薄片成形及物理性能的影响

本研究结合稠浆法加热不燃烧型烟草薄片浆料的特征,探究了黏结剂种类及添加量对烟草薄片成形及物理性能的影响。通过对烟粉的理化特性进行表征,并结合Zeta电位、阳离子需求量分析,对比了不同添加量下,羧甲基纤维素钠、甲基纤维素、羟丙基瓜尔胶、黄原胶4种黏结剂制备所得稠浆的黏度稳定性及烟草薄片的物理性能。结果表明,当羟丙基瓜尔胶添加量为2%(相对于烟粉绝干质量,下同)时,稠浆黏度从23403 mPa·s增至27546 mPa·s,烟草薄片匀度可达92,抗张指数3.55 N·m/g,紧度1.12 g/cm^(3),透气度下降至0.30μm/(Pa·s);当黄原胶添加量低于3%、羟丙基瓜尔胶添加量低于2%时,稠浆具有较好的稳定性,可有效改善烟草薄片的成形,提高其物理性能。

Research on the cuttings discharge in air cushion chamber of slurry shield based on CFD-DEM coupling method Author links open overlay panel

The rapid discharge of cuttings from the air cushion chamber is crucial for the construction safety and excavation efficiency of the slurry shield.Previous studies have mainly focused on the transport characteristics of cuttings in the slurry discharge pipe,while the complete process of cuttings entering the slurry discharge pipe from the air cushion chamber until they are discharged was often overlooked.Based on the CFD-DEM coupling method and combined with actual engineering,this paper established a numerical model that can more completely reflect the cuttings discharge process during slurry shield tunneling,and the effects of the slurry velocity at slurry gate and scouring pipes,inclination angle of slurry discharge pipe,cuttings diameter and shape coefficient were investigated by analyzing the variation in the mass flow rate,mass of discharged cuttings,and discharged ratio.The results revealed that increasing the slurry velocity can promote the discharge of cuttings.To keep the discharged rate at a high level,it is recommended that the slurry velocity at the slurry gate should be greater than 0.15 m/s.Reducing the inclination angle of the discharge pipe is conducive to the rapid discharge of cuttings.Cuttings with large diameter or small shape coefficient are more prone to accumulate in the air cushion chamber and cause clogging risk.The research results not only help to improve engineers'understanding of cuttings discharge in slurry shield,but also provide practical guidance for formulating relevant construction measures.

基于响应面法的废石-细尾砂充填性能优化试验

为获得满足矿山采矿强度要求的废石-细尾砂充填最佳配比,首先根据混合骨料的堆积密实度和料浆浓度初探试验,初步获得配比范围;在此基础上利用响应面法建立了以废石-细尾砂充填体的3、7、28 d抗压强度为响应值的回归模型,揭示了骨料配比、浓度和灰砂比三因素对充填体强度的影响规律,并通过回归模型优选出充填最佳配比,进行半工业试验验证。结果表明,当充填体养护至3、7 d时,浓度和灰砂比两因素的交互作用影响显著;当充填体养护至28 d时,骨料配比与浓度的交互作用影响显著。当骨料配比1∶3、浓度82%、灰砂比1∶4时,废石-细尾砂充填性能完全满足矿山的充填需求,为废石-细尾砂混合骨料膏体充填性能优化提供了理论基础。

磁铁矿矿浆的矿石质量流量检测新技术

针对选矿过程中强磁性磁铁矿矿浆所包含矿石质量流量难以检测的问题,在分析现有主要检测技术的基础上,结合应用现场流程的特点,创新性提出一种单流量-双浓度的矿浆质量流量检测法,通过检测流程加水的流量以及加水前后矿浆浓度的变化,实现对强磁性磁铁矿矿浆所包含矿石质量流量进行精确检测。实际应用表明:该方法具有检测精度高、适应性强、稳定性好等特点,特别适用于含有磁铁矿的矿浆。