界限含水量试验的探讨

对采用液、塑限联合测定法测定土的液、塑限试验的有关问题进行探讨 ;并通过玉树隆宝湖地区粘土的实测分析 ,说明选用适当的试验标准对减少误差 。

掺加外加剂改良过湿土的含水量损失及击实试验

对雅安地区过湿土样的物理力学性能进行了室内试验分析,通过掺加石灰、水泥及EN-1土壤固化剂改良过湿土,进行了改良土含水量损失及击实试验研究,以确定掺加不同外加剂、不同配合比的改良土的最优含水量,为掺加外加剂过湿土改良技术的后续研究奠定了基础。

联合站常温脱水正交试验

孤岛油田一直采用化学加热联合脱水。经试验对运行参数进行优化 ,实现夏季停用原油脱水加热炉 ,达到了节能降耗的目的 ,年节约成本 353 6万元。孤岛油田联合站于 2 0 0 0年 5月 1日开始正交试验 ,对原油脱水运行参数进行优化 ,试验在加热炉未使用的情况下顺利进行 。

生石灰改良过湿土的试验研究

通过界限含水量试验、击实试验、掺生石灰后含水量损失试验研究了不同的石灰掺入量对石灰土的液限、塑限、最大干密度ρdmax、最优含水量wop及掺生石灰后含水量损失的影响,并确定了该过湿土改良中石灰的最佳掺入量。

利用微型机进行土工试验数据处理

土工试验是工程地质工作的重要组成部分之一。它为地基工程地质勘察报告提供了土的物理力学性质指标。 近年来,随着基建和城建的迅速发展,土工试验的任务日益增加,传统的手工计算方法对所测得数据进行处理,已不能满足生产实验的需要。目前。

稻谷通风技术系列报道

对我国稻谷通风技术作了较为全面而简要的介绍其内容有:1、稻谷通风降水技术;2、稻谷通风降温技术;3、稻谷增湿调质通风技术;4、利用通风进行杀虫的环流熏蒸技术。 理论与实践表明,掌握气候条件、合理设计通风系统、正确选择风机等措施,能使稻谷达到要求的储藏水份和温度的标准以及良好的防治害虫效果。其储藏品质良好并能节省能源,降低成本,具有显著的经济效益和社会效益。

关键土力学指标在国内外规范间的对比分析

若干关键土力学指标,如液限、塑限及土粒组划分、土命名、标准贯入试验等的试验方法与划分标准在国标、英标及美标的岩土工程相关规范间差异较大,本文通过规范间相应指标的对比分析,结合相关工程经验,初步探讨指标使用过程中的相互转化或经验关系,有利于关键土力学指标在不同规范间之间融合,为同类工程提供参考。

Investigation on reinforcement-sand-clay layer system using direct-shear test

The property of the contact surface between geosynthetics and soil directly affects the whole structure＇s stability. The interface property is one of the most important indices for the reinforced structure. Systematic direct-shear tests with large direct-shear apparatus are carded out for geobelt reinforced clay under different normal stresses and water content. A reinforcement-sand-clay layer system improving the interface behavior greatly is designed. The stress-strain relationship is investigated on the basis of the experimental results. The results show that with the increase of the normal stress, the shear strength between the clay and the reinforcement increases nonlinearly, and with the increase of the water content, the friction coefficient between the clay and the reinforcement decreases dramatically and the cohesion between the clay and the polypropylene geobelt increases initially, then decreases. There is an optimal value for the water content between the clay and the polypropylene geobelt, which is 2% lower than the optimal water content of clay compaction. This reinforcement-sand-clay layer system improves the shear strength of the interface remarkably. Therefore, the clay-sand-reinforcement layer system is a rather good design for practical use in reinforcement engineering.

湿稻谷的短期保管方法

稻谷收割后如遇连阴雨,暂时难以晒干时,可以用下述几种方法临时处理,能安全保管7天左右,对稻谷食用品质不会有影响。

Soil-water characteristics and shear strength in constant water content triaxial tests on Yunnan red clay

The shear strength parameters for geotechnical designs are obtained mainly from consolidated drained （CD） or consolidated undrained （CU） triaxial tests. However, during construction, the excess pore-air pressure generally dissipates instantaneously while the excess pore-water pressure dissipates with time. This condition needs to be simulated in a constant water content （CW） triaxial test. The study on Yunnan red clay is carried out to investigate the soil-water characteristics and the shear strength characteristics under the constant water content condition. Osmotic technique is used to obtain the soil-water characteristic curve. A series of CW triaxial tests are conducted on statically compacted specimens. The experimental results show that the soil-water characteristic curve has a low air entry value of 7 kPa due to large pores in non-uniform pore size distribution, and a high residual value exceeding 10 MPa. In addition, the initial degree of saturation and net confining stress play an important role in affecting the shear characteristics under the constant water content condition. Finally, a new semi-empirical shear strength model in terms of degree of saturation is proposed and then applied to Yuunan red clay. Simulation result shows that the model is capable of capturing some key features of soils. The model can be used in whole engineering practice range, covering both unsaturmed and saturated soils.

液塑限在路基工程施工中的应用探讨

通过对液塑限的影响因素、液塑限试验的适用范围和工程实例的分析,提出对于依JTJ051-93所得的液塑限指标值在公路路基施工中,应按超过0.5mm的大颗粒质量占总土体质量的多少进行适当的修正,更符合工程实际。

石灰改良过湿土在均质坝填筑中的应用

以某粉质黏土均质挡水坝为例,由于其料源含水量偏高,通过界限含水量试验、击实试验、掺生石灰后含水量损失试验研究了不同的石灰掺入量对石灰土的液限、塑限、最大干密度、最优含水量及掺生石灰后含水量损失的影响并确定了该过湿土改良中石灰的最佳掺入量。介绍了整个研究与实施过程。

Stress-strain relationship of unsaturated cohesive soil

A moisture-content based constitutive model was proposed based on the hyperbolic model as an attempt to move towards the implementation of unsaturated soil mechanics into routine geotechnical engineering practice. The stress-strain behavior of in-situ soil at a depth of 5 m was investigated by conducting undrained triaxial compression tests using the remolded soil samples. The test results show that the stress-strain relationship of unsaturated cohesive soil is still hyperbolic. The values of parameters a and b given in the model decrease with increasing the confining pressure for soil samples with the same moisture content and increase with increasing the moisture content for soil samples under the same confining pressure. The relationships between parameters a, b and moisture content were studied for confining pressures of 100, 150, 200 and 250 kPa. The comparison between the measured and predicted stress-strain curves for an additional group of soil samples, having a moisture content of 25.4%, shows that the proposed moisture content-dependent hyperbolic model provides a good prediction of stress-strain behavior of unsaturated cohesive soil.

核子水分密度计在大梁水库施工质检中的应用

核子水分密度计控制土坝填筑质量较传统方法测试速度快、精度高、误差少。应用ＦＴ－６２８型核子水分密度计对万家寨引黄入晋工程的大梁水库筑坝施工的质检，首先作了与环刀法、酒精烘烧法测干容重、湿容重、含水量的对比试验，核子水分密度计测试数值比环刀法、酒精烘烧法高２％～２．５％。然后根据对比试验结果绘制相关关系图。利用对比试验结果绘制的相关关系图求干容重、湿容重、含水量控制筑坝质量，较传统法减少质控人员１／２，工效提高４～５倍。（唐茂无）

Effect of Micro Silica on Compressive Strength of Plastic Concrete

This research describes a series of laboratory tests performed to characterize the mechanical properties of plastic concrete. The mechanical properties of plastic concrete are studied using a series of compression tests. Stress relaxation and controlled rate of loading tests are also performed to investigate the rate sensitivity and time-dependency of plastic concrete. An important requirement for the plastic concrete in such applications is adequate strength for the design loads. The replacement of cement content of plastic concrete by micro silica does not result in any significant decrease in workability of plastic concretes and hence, unlike the case for normal concretes, plasticizers or super plasticizers are not required to rectify the adverse effect of micro silica on workability. The aim of the experimental research was to investigate the effects of various levels of cement replacement by micro silica, including 0%, 3%, 6%, 9%, 12% and 15% on strength of plastic concrete. Obtained results show that the effect of micro silica on strength enhancement of plastic concretes is substantial and a replacement level of 15% resulted in 70%-180% increase in strength compared to the control mix. For normal concretes, the increase in strength due to incorporation of micro silica was generally reported as 30%-50%.

Study of Sandy Soil Compaction

In this paper, a study of sandy soil compaction with different granulometry and moisture content has been performed, and soil mechanical property variations in moisture and granulometry have been investigated. Investigations were performed to compare hydrostatic compression test （HCT） responses and evaluate the compression index, Cc, which is an indicator of the soil＇s susceptibility to compaction-induced damage. The experiments have been performed on 24 soil samples typologies. Each sample has been obtained by combining three types of soil granulometry （types A, B and C） with a relative content varying from 0% to 100% in 20% increments. Soil type A had a granulometry ranging between 0.5 mm and 1 mm, type B between 0.25 mm and 0.5 mm, and type C less than 0.25 mm. These samples were representative of a sandy soil, chemically inactive and had various granulometries and initial moisture contents. A cell for HCT has been set up to allow the initial volume measurement of the test pieces and the subsequent changes during HCT with an estimated error less than 0.1 cm3. All samples were pre-compacted and prepared in agreement with the actual standards. The experimental data are reported in diagrams, the data allowed comparison of the mechanical behaviors between the considered unsaturated soils and underlined how soil moisture and granulometry affect soil response during HCT. Furthermore, because of the methodology used, the equipment was very economical.

土压平衡盾构刀盘泥饼堵塞改善研究

盾构刀盘泥饼堵塞会减慢施工速度,严重时还会导致塌方等工程事故。为了研究水化学-力学耦合作用下对盾构刀盘渣土流塑性以及强度的影响,使用0 mol·L^(-1)、0.5 mol·L^(-1)、1.0 mol·L^(-1) CaCl_(2)溶液对盾构刀盘渣土进行饱和,并对饱和后的土样进行界限含水量试验以及改良的直剪试验。试验结果表明,盐溶液的增加能够有效地降低土样的液塑限以及塑限指数;剪切强度有所增加,黏聚力降低,内摩擦角增大。主要是因为结合水膜在高浓度下变薄,土样持水能力变弱导致液塑限的降低;盐溶液浓度的增加抑制了土样双电层厚度,使得土颗粒团聚,颗粒之间的排斥力减弱,土颗粒的咬合力增强,于是黏聚力减弱、内摩擦角增大。在沿海地区以及盐渍土地区进行渣土改良时,应该避免盐分的加入,降低土中的盐分能够有效降低盾构刀盘渣土的强度,研究对盾构刀盘渣土改良有着一定的指导作用。