Comparative experimental investigation of chemical grouting into a fracture with flowing and static water

We present a series of experimental tests on chemical grouting into a fracture with flowing and static water,using a transparent fracture grouting experimental device.Variations of seepage pressure and grout propagation were compared in our investigation.The results show that flowing water results in drops of seepage pressure,development of penetration radii in the upstream side and drops of propagation area during the same period,compared with grouting in static water.The propagation area in static water is always round before grouts reach the joint boundaries.However,the propagation shape changes from round to an elliptic shape for grouting into a fracture with flowing water.A theoretical model for the grout penetration radius in a fracture considering flowing velocity was developed and validated by our experimental results.These results are helpful in improving understanding of fracture grouting mechanism and in guiding engineering practices.

Experimental study on desorption of soluble matter as influenced by cations in static water

With variation of drainage basin environments, desorption of soluble matter has become one of the significant erosion processes in rivers. It has a considerable impact on flow and sediment transport, as well as processes of river bed deformation and landform evolution throughout a watershed. In this study, considering influences on sediment movement, especially on cohesive sediment transport, Ca^2＋ and H^＋ were chosen as characteristic ions of soluble matter, and the total desorption quantity of Ca^2＋ and pH value when the desorption equilibrium is reached were employed as two indexes representing the desorption of soluble matter. By means of an indoor experiment, desorption of soluble matter as influenced by cations in static water was investigated. The results show that the total desorption quantity of soluble matter increases with the initial cation concentration until a maximum desorption quantity value is obtained and maintained. The total desorption quantity of soluble matter depends on properties of the specific cations in static water, and the stronger the affinity is between the cation and sediment surface, the higher the total desorption quantity will be. Finally, a strong approximate linear relationship between desorption quantities for different kinds of soluble matters was obtained, which means that variation of pH values can accurately reflect the desorption results of soluble matter.

Spatial and Temporal Evolution of the Static Water Level of the Cuauhtemoc Aquifer during the Years 1973, 1991 and 2000: A Geographical Approach

In hydrogeology it is of great interest to examine the temporal and spatial evolution of aquifers. There are different ways of modeling an aquifer: physical models, models based on analog and mathematical techniques. Usually, mathematical techniques involve complex operations difficult to understand for some people, such as differential or partial equations. In contrast, our method requires only a basic knowledge of geometry and trigonometry. Moreover, it is only necessary to know the static level of the aquifer at three different dates. Of course, the results may be limited compared to those that use advanced mathematical methods;however, our method provides a first approximation to determine the behavior of the aquifer through time. Overall, our results allowed us to follow the evolution of the aquifer in detail of various areas of increased extraction and in which removal has been increasing, but also of areas with a considerable recharge during the study period.

Contaminations removal from static lake water by compound

Urban wastewater treatment techniques could not be applied to improve the pollutant removal efficiency,due to its characteristics of closed and quiescent conditions of the static lake water.In this study,natural zeolite and coal cinder were chosen as filler compounds of the ecological filter.Static and dynamic experiments were carried out to study the remediation efficiency.Experimental data show that removal efficiency of ammonia nitrogen （NH ＋ 4 -N） reaches 85% in both static and dynamic patterns and its removal efficiency reaches 97% when the recycling period is 1 h in dynamic condition.The maximum removal efficiency of nitrite nitrogen （NO-2 -N） reached 98%,and the removal efficiency of total nitrogen （TN） is a maximum of 84%.The final effluent concentration of total phosphorus （TP） is 0.079 mg/L.Effluent recycling could improve the nutrient （N,P） removal efficiently.Dissolved oxygen （DO） concentration could remain high with the water cycling.The filter works efficiently on regulating pH to the standard level of healthy water.

Succession and biodiversity indices in eutrophication process of static landscaping water body in northern China

Many biodiversity indices were used to indicate the biological contamination degree in studies of lake water or seawater. Some were studied on biodiversity comparison for different areas at the same time, or initial structure succession of some aerial lake water systems. The phytoplankton changed with the development of various dominant species. In this study, the dominant species at these stages were Chlorophyta in the beginning stage, Cyanophyta in the second stage, and Xanthophyta in the last stage. Seven of nine biodiversity indices (Margalef's, IE, Shannon-Wiener, Simpson's, McNaughton's, Species and Odds Measure of Diversity) showed their failure to represent the eutrophication trend, and the other two indices (Menhinick's and Monk) exhibited good efficiency to indicate the eutrophication trend for the static landscaping water body.

Effects of hysteresis of static contact angle (HSCA) and boundary slip on the hydrodynamics of water striders

It is known that contact lines keep relatively still on solids until static contact angles exceed an interval of hysteresis of static contact angle (HSCA), and contact angles keep changing as contact lines relatively slide on the solid. Here, the effects of HSCA and boundary slip were first distinguished on the micro-curvature force (MCF) on the seta. Hence, the total MCF is partitioned into static and dynamic MCFs correspondingly. The static MCF was found proportional to the HSCA and related with the asymmetry of the micro-meniscus near the seta. The dynamic MCF, exerting on the relatively sliding contact line, is aroused by the boundary slip. Based on the Blake-Haynes mechanism, the dynamic MCF was proved important for water walking insects with legs slower than the minimum wave speed . As insects brush the water by laterally swinging legs backwards, setae on the front side of the leg are pulled and the ones on the back side are pushed to cooperatively propel bodies forward. If they pierce the water surface by vertically swinging legs downwards, setae on the upside of the legs are pulled, and the ones on the downside are pushed to cooperatively obtain a jumping force. Based on the dependency between the slip length and shear rate, the dynamic MCF was found correlated with the leg speed U, as , where and are determined by the dimple depth. Discrete points on this curve could give fitted relations as (Suter et al., J. Exp. Biol. 200, 2523-2538, 1997). Finally, the axial torque on the inclined and partially submerged seta was found determined by the surface tension, contact angle, HSCA, seta width, and tilt angle. The torque direction coincides with the orientation of the spiral grooves of the seta, which encourages us to surmise it is a mechanical incentive for the formation of the spiral morphology of the setae of water striders.

大田水肥一体化混肥器设计与试验研究

由于当前市场上没有既适合大田大面积灌溉、混肥精度又高的水肥一体化系统,故在旁路式结构设计中增加静态混合器替换主管道,以提高混肥均匀性为重点进行研究,对混肥部件进行了优化改进。利用混合器自身结构,在不需要外接能源的条件下,使得水肥充分混合,不仅能够满足大面积灌溉要求,而且可以保证混肥精度。基于流体力学及CFD基本原理,通过Fluent软件分析水肥混合过程中SK型静态混合器混合单元数,以及长径比对水肥混合性能和压降的影响,以此找出混合器的最佳结构参数,并对其结构做了改进,设计出了开沟式静态混合器。

Innovation for Making Potable Water Available in Saline Groundwater Areas

Groundwater salinity is a widespread problem around the world with adverse consequences on health, soil quality and overall eco-systems. With the rapidly growing demands of groundwater, its exploitation is also accelerating. It is also changing the flow of the groundwater, which in turn causes ingress of sea water or intrusion of other saline groundwater or polluted water from the surrounding areas. The major consequences are scarcity of water even for domestic use and rise in the level and spread of groundwater salinity. An innovative technique of creating a pool of fresh groundwater within a saline aquifer is developed, which can address the issue. Technique is about recharging the saline aquifer with harvested rain water in such a way that recharged rain water does not get mixed with the existing saline groundwater rather it forms pool of fresh water in the saline aquifer. Water from this pool can be extracted without getting it mixed with saline groundwater. This innovation also eliminates the need of cost intensive provision of water storage structures to store rain water for fulfilling the domestic water needs. Thus, the saline aquifer unsuitable or otherwise useless for groundwater development can be used.

水热法合成超细斜发沸石试验研究

斜发沸石具有较强的吸附和离子交换能力,在重金属和油污废水去除、制糖、造纸净化、抗菌抗癌药物助剂制备、石油化工催化裂化、国防以及CO_(2)脱除等领域应用广泛。为了获得纯度较高的斜发沸石,以NaOH、KOH、Al(OH)_(3)、Na_(2)O·nSiO_(2)、H_(2)O为原料,采用水热法制备了斜发沸石,并通过XRD和晶面分析,研究了斜发沸石的合成条件,结果表明:合成斜发沸石的最佳条件为n(SiO_(2))/n(Al_(2)O_(3))=11、n(OH-)/n(SiO_(2))=0.55、n(H_(2)O)/n(SiO_(2))=25~55、温度150℃、时间6 d,合成的斜发沸石呈片状结构,特征峰完整,纯度较高,其晶胞组成为Na_(0.36)K_(6.58)[(AlO_(2))6(SiO_(2))_(25.26)]·6.71H_(2)O,n(SiO_(2))/n(Al_(2)O_(3))约为8.5,属中硅铝比沸石。SEM分析结果显示,其粒径在1.3μm以下,表明粒度非常细;其静态水吸附量为34.3%,达到了HG/T 2690-2012《13X分子筛》中的一等品指标要求。研究成果可为高纯度细粒斜发沸石的精准合成提供借鉴。

静力试验中水载荷控制过程建模与仿真

针对结构静力试验中极小载荷多点协调程控加载的需求,提出了以慢速比例阀为执行结构、水箱内液体重力为控制目标的试验方法,建立了水载荷控制模型。为提高试验控制系统的响应速度,设计了直接数字量控制算法并与经典PID控制算法进行了对比。仿真结果表明,该试验方法能够实现静力试验中极小载荷闭环控制,直接数字量控制算法优于经典PID控制算法。

薄板式静态混合器混合性能数值模拟

薄板式静态混合器内构件简单、通量高、压降低,可以有效降低稀释水掺混能耗。文中以不均匀系数ψ和管路压降Δp作为评价指标,利用CFD(计算流体动力学),对比分析单直管、单顺流羽状管、单逆流羽状管和双顺流羽状管等4种注水方式的混合效果和压降。研究发现,在注水管安装在L/D=5.3处,单管注入时,注水两侧形成的径向二次流强度Se变化缓慢,稳定的涡旋流在混合器内产生混合“死区”,降低了静态混合器的油水混合速度;当ψ降至0.05时,混合距离超过18D。此混合死区解释了单管注入时分散相注入点附近易出现局部高浓度区。双顺流羽状管注入时,对撞水相产生较高径向二次流强度Se,且迅速降低。快速变化的流场显著减少混合距离,与单管注入相比,ψ降至0.05时混合距离减少76.9%,Δp增加1.5%。

极浅水域船舶航行阻力及下沉量数值计算方法

针对舰船在极浅水域中的航行阻力及航行安全预报问题,提出了静力平衡方程与叠模定常流计算相结合的数值计算方法。经分析比较可知,该方法只需进行一次姿态调整,姿态收敛偏差即可小于5%。水动力计算结果与水池模型试验结果对比表明:当深度/吃水比(h/T_(m))为1.18时,阻力预报相对偏差为3%左右、下沉量绝对偏差小于2 mm,触底航速预报相对偏差小于5%。该方法可有效避免计算过程中姿态波动导致解算失败的问题,具有良好的计算稳定性和收敛性,且计算精度较高,可为浅水航行船舶航行性能数值计算提供借鉴和参考。

南水北调中线北京段岩体隧洞围岩变形模量分析研究

岩体力学参数是影响地下工程围岩稳定的重要因素,确定合理的岩体变形模量对隧洞设计至关重要。结合南水北调中线北京段西甘池试验洞工程,对岩体进行静载荷试验分析研究,详细介绍试验点岩体的加卸载变形关系曲线,获得西甘池隧洞岩体变形模量参数建议值,为工程设计提供依据,并以期为类似工程的设计和施工提供参考。研究结果表明:试验压力较小时,各试点岩体变形或弹性模量的变化曲线有的升、有的降,试验压力大于0.4 MPa以后,各试点的变形模量和弹性模量逐渐趋于稳定;隧洞围岩变形控制及支护结构设计时,应根据各段围岩的岩性(大理岩、滑石片岩)、结构完整性、节理裂隙的空间展布方式以及发育充填情况等综合考虑,结合工程类比和地质经验最终确定岩体弹性参数的基本代表值。研究的方法和结论可为类似条件下隧洞工程的设计、施工提供参考和借鉴。

静态破碎剂性能分析及致裂效果实验研究

为解决现有煤矿井工开采过程中预裂爆破安全性低、适用性差以及水压致裂条件苛刻,破岩效果弱的问题,提出静态致裂的方法,通过研究不同影响条件下静态破碎剂的反应状态和致裂效果,对不同拌合水温、水灰比条件下的静态破碎剂反应温度、反应时间、反应体积变化、岩样致裂效果、应力变化进行了研究。结果表明:水灰比一定,静态破碎剂完全反应时间随拌合水温升高而降低,但最终反应完全后温度不变;相同拌合水温条件下,水灰比越小,静态破碎剂反应时间越短,反应速率越快;水灰比越小,混凝土试件开裂时间越短,水灰比越大,开裂时间越长,开裂效果与裂缝位置有关,块体应变呈现先增后减的趋势。

基于运动轨迹约束的静水压激励法水听器校准

针对传统静水压激励法水听器校准系统中,由于连通软管欠约束导致连通软管内水体振动时惯性力对等效声压的影响不一致,从而引起由测量重复性引入的不确定度偏大,影响水听器灵敏度校准不确定度的问题,提出了基于运动轨迹约束的静水压激励法水听器校准方法。该方法设计了运动约束装置控制连通软管在振动时产生相同的运动轨迹,基于此建立数学模型确定了连通软管部分振动对等效声压的影响,推导出不受限于水听器开路电压测量数据的等效高度计算公式。搭建了基于运动轨迹约束的静水压激励法水听器校准装置,并与传统方法进行了比对。实验结果表明:相较于传统静水压激励法,该方法将水听器灵敏度校准的不确定度由0.34 dB(k=2)减小到0.25 dB(k=2),其中由测量重复性引入的不确定度从0.12 dB减小到0.02 dB。

水雾环境下密闭舱室内爆准静态压力特性试验研究

[目的]旨在探究水雾环境下的密闭舱室内爆准静态压力特性。[方法]首先,基于绝热的理想气体舱室内爆准静态压力理论模型,新增2个假设,建立水雾环境下的密闭舱室内爆准静态压力理论模型;然后,以药量为自变量,开展有/无水雾的密闭舱室内爆对照试验,测量准静态压力以验证水雾对准静态压力的削弱效应,并得到准静态压力经验公式。[结果]理论模型和试验数据分析表明:随着药量-体积比的增大,水雾减弱了内爆准静态压力的增强能力,增长率逐渐降低;引入后燃烧修正项的理论公式与经验公式均可用于预估舱内准静态压力峰值。[结论]试验结果验证了水雾对准静态压力的削弱效应,基于理论模型和相关试验数据拟合得到了水雾环境下内爆准静态压力峰值的经验公式。

非平坦海底地形条件下悬链式系泊链静态特性研究

对于在沿海或海岛泻湖附近水域进行作业的浮体,因其较浅的工作水深使得海底地形变化对其系泊系统的影响不可忽略,因而在探究系泊系统特性时不能再将海底简化为平坦地形。为研究锚链在非平坦海底地形条件下的静态特性,基于集中质量法建立锚链模型,通过数值模拟探讨海底倾斜角度以及锚链布置方式对锚链顶端张力、张力角以及悬线长度的影响规律,以指导浅水水域浮体系泊系统的设计和安全性能评估。

高压水炮系统水箱与连接件静态特性分析

消防直升机因其高机动性、大载质量和长航时等优点而被广泛应用于扑灭森林、超高层建筑和危化品场所等火灾。为防止结构问题引发安全事故,需要对其外挂水炮系统结构进行静力学分析,确保设计的外挂水箱结构强度和刚度符合适航标准。首先,使用SolidWorks软件建立了消防直升机外挂水箱和连接件的三维模型,并进行了适当的简化。然后,通过有限元分析软件对水箱及各连接件进行了静力学分析。仿真结果表明,所设计的高压水炮系统的水箱及连接件结构具有良好的静态特性,能够满足适航要求,并能保证系统的正常运行和性能表现。

基于ANSYS水环真空泵转子静力学和模态分析

水环真空泵具有构造简单、等温压缩、方便使用维修等特点,特别适合抽吸和压缩易燃易爆气体。转子部件在水环真空泵的稳定运行中发挥关键作用,其设计强度直接影响着产品的质量和寿命。通过ANSYS有限元分析软件对转子部件进行了静力学分析和模态分析。结果表明:水环真空泵泵轴和叶轮最大变形量均未超过材料允许的变形量。通过模态分析可知水环真空泵工作转速远低于转子系统的一阶临界转速,系统不会发生共振。研究验证了水环真空泵的工作可靠性,为转子部件以及产品整体结构优化设计提供了理论依据。

水基完井液静态沉降稳定性影响因素研究

通过研究不同密度的水基完井液在不同温度下沉降1~15 d的流变性能、滤失性能和沉降稳定性,计算不同因素间的皮尔森系数绘制热力图,考察了不同因素对静态稳定分层指数(SSSI)的影响。实验结果表明:沉降15 d内,不同密度完井液的清液量与SSSI值的相关性系数均达到0.91;完井液密度、老化时间以及沉降温度与SSSI值的相关性系数分别为0.64、0.58和0.23,即沉降稳定性的影响因素由大到小排列的顺序为完井液密度—老化时间—沉降温度,但沉降温度、老化时间分别与密度呈现竞争关系。