单体液压支柱稳压试验系统升级改造

由于井下复杂地质条件及人为因素影响,单体液压支柱易老化、损坏,对回收上井的液压支柱必须进行定期检修,合格后方可继续使用。稳压试验是保证单体液压支柱检修质量和安全的一个关键工序,机械式稳压检测仪检测时间长、误差大,经过对原有的DK-3型单体液压支柱密封质量检测系统进行升级改造,取得较好效果。

NBJ85—Ⅰ全自动液体包装机横竖封自动稳压试验研究

本文介绍了NBJ85—Ⅰ全自动液体包装机当电网压波动时对横竖封热合质量等方面的影响 ,分析了横竖封自动稳压电路的工作原理并对试验结果和应用效果作了分析和总结。

稳压器连续喷淋调节定期试验执行方法及优化

大亚湾核电站每次大修都需要执行稳压器喷淋阀定期试验,但该试验返工的几率很大。本文就该试验的方法和可能出现的问题进行了探讨。

电厂直流系统试验分析及改进方案

2005-03,内蒙古国华准格尔发电有限责任公司在1号机大修期间对直流设备进行了直流系统充电器稳压、稳流试验,直流开关特性测试等,发现了存在的问题,提出了改进方法,并进行了实施。

Stabilization of saline silty sand using lime and micro silica

Many construction and post-construction problems have been reported in the literature when saline soils have been used without understanding of their abnormal behavior,especially their inferior bearing capacity in the natural condition.The strength of these soils further decreases on soaking.Saline soil deposits cover extensive areas in central Iran and are associated with geotechnical problems such as excessive differential settlement,susceptibility to strength loss and collapse upon wetting.Because of these characteristics,some of the roads constructed on saline soils in Taleghan area have exhibited deterioration in the form of raveling,cracking and landslides.The main objective of this work is to improve the load-bearing capacity of pavements constructed on Taleghan saline soils using lime and micro silica.Soil samples from Hashtgerd-Taleghan road were collected and tested for improving their properties using lime and micro silica at different dosages ranging from 0 to 6%.The load-bearing capacity of stabilized soil mixtures was evaluated using California Bearing Ratio(CBR) and unconfined compressive strength tests.The test results indicate that the lime improves the performance of soil significantly.The addition of 2% lime with 3% micro silica has satisfied the strength-deformation requirements.Therefore,improved soil can be used as a good subbase in flexible pavements.

Horizontal trap-door investigation on face failure zone of shield tunneling in sands

A novel horizontal trap-door test system was devised in this study to analyze the face stability of shield tunnels in sands.The test system can be used to investigate both the longitudinal and cross sections of the face failure simultaneously at one single apparatus and was employed to perform face stability tests on small-scaled tunnel models at single gravity.The lateral support pressures and failure zones were studied with varying sand materials and earth covers.The results demonstrate that the tunnel face moves back,the lateral active earth pressure on the tunnel face decreases rapidly to a residual value,and the lateral pressure distribution can be categorized into three stages during the failure process:1)initial state;2)pressure dissipation stage;and 3)pressure zone diminution stage.Furthermore,face failure firstly develops from a stable condition to the local failure state,and then continues to develop to the global failure state that can be divided into two sub-zones with different failure mechanisms:rotational failure zone(lower zone)and gravitational failure zone(upper zone).Further discussion shows that under the effects of soil arching,the shape of the gravitational failure zone can adopt arch shaped(most frequent)and column shaped(in shallow tunnels).Limit support pressure for face stability usually appears atδ/D=0.2%−0.5%(ratio of face displacement to tunnel diameter).

Processing map and hot working mechanisms of Cu-Ag alloy in hot compression process

For Gu-Ag alloy, an important parameter called workability in the forming process of materials can be evaluated by processing maps yielded from the stress-strain data generated by hot compression tests at temperatures of 700-850 °C and strain rates of 0.01-10 s-1. And at the true strain of 0.15, 0.35 and 0.55, respectively, the responses of strain-rate sensitivity, power dissipation efficiency and instability parameter to temperature and strain rate were studied. Instability maps and power dissipation maps were superimposed to form processing maps, which reveal the determinate regions where individual metallurgical processes occur and the limiting conditions of flow instability regions. Furthermore, the optimal processing parameters for bulk metal working are identified clearly by the processing maps.

Shear creep parameters of simulative soil for deep-sea sediment

Based on mineral component and in-situ vane shear strength of deep-sea sediment, four kinds of simulative soils were prepared by mixing different bentonites with water in order to find the best simulative soil for the deep-sea sediment collected from the Pacific C-C area. Shear creep characteristics of the simulative soil were studied by shear creep test and shear creep parameters were determined by Burgers creep model. Research results show that the shear creep curves of the simulative soil can be divided into transient creep, unstable creep and stable creep, where the unstable creep stage is very short due to its high water content. The shear creep parameters increase with compressive stress and change slightly or fluctuate to approach a constant value with shear stress, and thus average creep parameters under the same compressive stress are used as the creep parameters of the simulative soil. Traction of the deep-sea mining machine walking at a constant velocity can be calculated by the shear creep constitutive equation of the deep-sea simulative soil, which provides a theoretical basis for safe operation and optimal design of the deep-sea mining machine.