关于分散性土料改性试验的探讨

由于某些粘土在水中有不同程度的分散性，这是不少土坝失事的一个重要原因。文章通过对“６３５”工程及风城北高库过渡性土料加入额尔齐斯河水、不同比例石灰等改性试验的研究，对确定性试验方案，取得改性试验初步成果，做了详细的论述。     

水利工程筑坝土料分散性试验方法

土料的分散性是决定土料能否用于工程的重要因素,是土坝稳定性评价的一项重要指标。通过对小浪底、西霞院等工程的土料进行分散性试验,在借鉴国外研究成果的基础上,归纳整理出一套较为完整的土料分散性试验方法,包括交换性钠离子试验、饱和浸提液试验、双比重计试验、针孔试验及土块试验。     

某大坝防渗土料分散性试验研究

针对目前通用的分散性鉴定的5种试验方法,即双比重计法、针孔试验、碎块试验、孔隙水可溶盐阳离子试验和全土的交换性钠百分比试验的结果往往会出现不相吻合的情况,通过对某大坝防渗土料分散性的研究,从分散性机理和判断标准来分析不相吻合的原因,并认为应当深入研究分散性试验的定量化判断标准,促进分散性土鉴定试验规程的制定与实施.     

分散性土料筑坝的危害分析

针对老挝色萨拉龙灌溉工程,分析了原设计方案失败的原因,研究了分散性土的在工程应用中具有遇水分散的特性不适合直接作为上坝料。根据本工程的所在地区的实际情况,通过对分散性土进行改性处理,以满足工程需要。     

羟基铝改性分散性土的试验研究

利用羟基铝溶液作为改性材料,对东北某地典型的分散性土进行改性,通过针孔试验、碎块试验和双比重计试验研究了不同铝土比条件下羟基铝溶液对分散性土的改性效果,并结合土粒相对密度、颗粒组成、pH值及阳离子交换量等物理化学指标分析了羟基铝溶液对分散性土的改性机制.结果表明:羟基铝溶液加入后,土体相对密度明显降低、颗粒粒径变大、p...     

某心墙坝土料分散性判别与石灰改性土的性能规律分析

分散性土作黏土心墙会影响大坝的防渗安全,通过针孔试验、碎块试验对新疆某心墙土料的分散性进行了判别,分别采用天然河水与石灰进行改性试验,研究不同石灰掺量和陈化时间对改性土物理、力学性能的影响规律。结果表明,黏粒含量为12%是土料产生物理性、化学性分散的界限;采用天然河水进行改性,效果不佳,当石灰掺量为3%时,可完全消除分散性;土样掺入1%的石灰后,界限含水率变化明显,最大干密度由1.79 g/cm³降至1.69g/cm³、压缩模量由13.4 MPa增至19.4 MPa、黏聚力由25.1 kPa升至43.3 kPa;随石灰掺量的增加,最大干密度提高、内摩擦角减小,黏聚力增大;随着陈化时间的延长,液限呈增长趋势,最大干密度在24 h内较稳定,之后开始降低,240 h后趋于稳定,压缩性在72 h内变化不明显,而后开始增强。由于石灰中含有大量的钙离子,因此使分散性土的性能发生变化。     

吉林省乾安地区分散性土体改性试验研究

分散性土遇水容易分散流失,极易对水渠、大坝等造成冲沟、管涌等破坏,对水利工程造成不利影响.为降低工程灾害,需对分散性土进行改良.实验以吉林省乾安县分散性土体为研究对象,分别采用石灰+粉煤灰(比例1∶2)、水泥+石灰+粉煤灰(比例1∶1∶4)两种改性方案,通过针孔试验和碎块试验验证改性效果,并通过渗透试验探究改性剂对土体...     

新疆某工程土料分散性探讨

 新疆地区干旱,各工程筑坝土料基本都是由风化层经水流搬运至洼地及风化沉积土料,经蒸发形成受高钠影响具有一定分散性。土料的分散性是决定土料能否用于工程的重要因素,也是土坝稳定性评价的一项重要指标。对新疆某工程土料采用蒸馏水和河水2种方案进行分散性试验,认为河水中钙离子含量较高,进入土体后能抑制土样的分散性,河水对黏土分散性具有明显的影响。     

石虎塘航电枢纽工程土料分散性鉴定试验研究

利用双比重计、针孔、碎块和孔隙水可溶盐阳离子4种试验方法对南坪水库土样的分散性进行了研究.试验结果表明,土料K1以砂粒为主,K6、K8以粉粒为主;3组土料的钠含量小,可有效降低土料的分散性;这3组土样中K1、K6属于过渡性土,K8属于非分散性土.     

萧山粘土的结构性对渗透性质影响的试验研究

大多数天然沉积的粘土都具有一定的结构性 ,土的渗透性不仅与土的结构性密切相关 ,而且与土的强度、变形有关。土的渗透性是土力学主要研究课题之一。文章对萧山粘土在不同压力下进行原状土与重塑土的渗透试验 ,根据试验结果探讨了粘土的结构性对渗透性质的影响 ,得出一些有实际意义的结论 ,可供实际工程和设计参考。     

水对针孔试验鉴定分散性粘土结果影响的试验研究

通过研究土样配制用水和冲蚀用水对针孔试验鉴定分散性粘土结果的影响．认为在西郊和三坪土样中土样配制用水对土样的分散鉴定结果影响较小，而冲蚀用水对土样分散性鉴定结果可以产生很大的影响。     

EXPERIMENTAL RESEARCH ON THE SHAPE CHARACTERS OF NATURAL AND VENTILATED SUPERCAVITATION

A series of projectile and water-tunnel experiments were conducted to investigate the shape characters of natural and ventilated supercavitation. It was found that the shape and dimensions of both the natural supercavitation and the ventilated supercavitation are similar through the comparison of them when the cavitation number is small and equal, and the contour of both the natural supercavitation and the ventilated supercavitation can be calculated effectively with the Savchenko formula. The gravity effect can induce the asymmetry of ventilated supercavitation, and the asymmetry is more apparent as the Froude number is smaller. The empirical formula for calculating the axial deformation of ventilated supercavitation was corrected and expanded based on experiment data. The evolution rules of both the natural supercavitation and the ventilated supercavitation were described, and the vortex frequency of natural cavitation was obtained. In addition, the hysteretic aspect was observed between the development and the fall process of ventilated cavitation.     

EXPERIMENTAL RESEARCH ON RADIATION FROM DOUBLE CYLINDRICAL STRUCTURES

1. INTRODUCTION Induced by unbalanced mechanical forces and moments, underwater structures vibrate and radiate The main form of underwater structures, such a submarine, is reinforced double cylindrical structure immersed in water, with fluid media filled between th double cylindrical shells. In essence, this is a coupling problem between fluid and structure. Multipl methods have been used to estimate radiation leve from underwater structures[1-9]. Musha[10] and Chertock[11] estimate the …     

EXPERIMENTAL RESEARCH ON EFFECT OF MAIN-FLOW SWING ON FLOW TURBULENCE STRUCTURE

It is mentioned in this paper that the adjustment of flow structure occurs when themain-flow swings.The changes of turbulence structure and flow energy loss in the indoor rivermodel are measured.The experimental data are presented for the first time for the further studyof complicated river flow structure.     

EXPERIMENTAL AND THEORETICAL STUDY ON THE HIGH-SPEED HORIZONTAL WATER ENTRY BEHAVIORS OF CYLINDRICAL PROJECTILES

In this article,the horizontal water-entry of flat-nose projectiles of two different lengths at impact velocities of 400 m/s-600 m/s is studied experimentally and theoretically.Based on the solution of the Rayleigh-Besant problem,a set of projectile dynamic equations are derived and a cavity model is built to describe the projectile’s water entry dynamics.A parameter in the cavity model is determined by employing the principle of energy conservation.The results indicate that the flat-nose projectiles enjoy a good stability of trajectory,the drag coefficient and the velocity decay coefficient are dependent on the cavitation number,and increase along the penetration distance but with a relatively small variation.The maximum cavity radius decreases monotonically with the penetration distance.Projectiles with the same nose shapes at different initial velocities have a basically consistent cavity dimension before the deep pinching off phenomenon occurs.Good agreements are observed between results obtained by the analytical model and the experimental results.     

EXPERIMENTAL RESEARCH OF EQUILIBRIUM AND NONEQUILIBRIUM DYNAMIC ADSORPTION OF Cd~(++) IN SOIL--EFFECT OF DIFFERENT ACIDITIES AND SATURATION

This paper studies water and solute transport in soil. It mainly deals with theadsorption behavior of heavy metal Cd~(++) in soil at different P~H values and the dynamic charac-ters of adsorption process in unsaturated state. Through theoretical analysis and experimental re-search, the adsorption isotherm and the equations of dynamic adsorption in saturated and unsatu-rated states are proposed.     

EXPERIMENTAL RESEARCH ON A SUPERCAVITATING SLENDER BODY OF REVOLUTION WITH VENTILATION

The behavior of supercavitating and cavitating flow around a conical body of revolution with and without ventilation at several angles of attack was studied experimentally. The hydrodynamical forces for a range of cavitation number were measured. Comparisons of the appearance and the hydrodynamical forces in condition of cavity with and without ventilation were made over the same range of the cavitation number, and a well agreement was obtained. The changes of the drag were especially studied. The experimental results showed that the drag of the model decreased with the presence of supercavity under the ventilation condition.     

老愚公梯级水电厂技术改造

江西省奉新县老愚公梯级水电厂，因多年超龄运行，严重影响了安全可靠和水力资源的充分利用。为此在对原有机组性能进行测试及水文水能进行核算的基础上，对该水电厂技改方案进行了论证。     

罗边水电站机组和设备的技术改造

通过对罗边水力发电站机组一次系统、自动化系统施行技改，不仅提高了供电质量，增加了发电量，而且使机组自动化水平上了一个台阶，为实现计算机监控创造了有利条件．