复杂地质真空预压压力过低原因探讨

本文结合平潭某建筑场地真空预压地基处理密封膜下真空压力不足的工程实例,通过分析真空压力过低的原因,供有关工程参考。     

一起透平膨胀机管路断裂的分析

天科气体6500 m3/h空分设备配套的一台增压透平膨胀机,在正常运行时管道突然发生断裂。分析了故障原因,并阐述了处理措施。     

带台阶的D形橡胶密封圈密封特性分析

使用有限元方法分析一种新型带台阶的D形橡胶密封圈在不同预压缩率、工质压力和结构参数下的密封特性,并将之与相同尺寸的普通D形密封圈进行对比。分析结果表明:与普通D形密封圈相比,带台阶D形密封圈在高预压缩率下能获得更好的密封效果,但使用寿命较短;在低工质压力下,带台阶D形密封圈的密封性能更优,且使用寿命较长;在高工质压力下,2种D形密封圈的密封效果基本一致,但带台阶D形密封圈的使用寿命较短;结构参数H_1/H_2(底座矩形高度与截面弧形高度比)是影响D形密封圈密封性能的重要参数,当H_1/H_2的比值为3∶1时,2种D形密封圈的综合密封性能最优。     

粗糙表面间密封性能研究进展

在微观尺度下的静密封界面表面形貌是粗糙不平的，两粗糙表面上的微凸体在载荷作用下会接触形成孔隙；随着接触压力的减小或观察尺度的增加，当孔隙增加到一定数量时孔隙之间会相互连通形成泄漏通道，影响密封性能。现有的粗糙表面密封分析基于均化思想、逾渗理论和多孔介质思想等方法建立泄漏通道模型，考虑表面粗糙度、表面纹理以及表面载荷等对密封性能的影响。对现有的粗糙表面间密封性能的研究现状进行综述，分析现有的粗糙表面密封研究方法存在的不足之处，指出粗糙表面间密封研究可能的方向，为进一步研究粗糙表面密封机制提供了参考。     

Chromophore-Free Sealing and Repair of Soft Tissues Using Mid-Infrared Light-Activated Biosealants

Poor strength, infection, leakage, long procedure times, and inflammation limit the efficacy of common tissue sealing devices in surgeries and trauma. Light-activated sealing is attractive for tissue sealing and repair, and can be facilitated by the generation of local heat following absorption of nonionizing laser energy by chromophores. Here, the inherent ability of biomaterials is exploited to absorb nonionizing, mid-infrared (midIR) light in order to engender rapid photothermal sealing and repair of soft tissue wounds. In this approach, the biomaterial simultaneously acts as a photothermal convertor as well as a biosealant, which dispenses the need for exogeneous light-absorbing nanoparticles or dyes. Biomechanical recovery, mathematical modeling, histopathology analyses, tissue strain mapping using digital imaging correlation, and visualization of the biosealant-tissue interface using hyperspectral imaging indicate superior performance of midIR sealing in live mice compared to conventional sutures and glue. The midIR-biosealant approach demonstrates rapid sealing of soft tissues, improves cosmesis, lowers potential for scarring, obviates safety concerns because of the nonionizing light used, and allows adoption of a wide diversity of biomaterials. Taken together, the studies demonstrate a novel advance both in biomaterials for surgical sealing along with the use of nonionizing midIR light, with high potential for clinical translation.     

新旧水泥砂浆界面粘结性能试验研究

在荷载和环境因素作用下,混凝土结构产生不同程度的劣化。为了保证结构的安全性和耐久性,需要对损伤水泥基材料进行修复。基体的含水饱和度、界面粗糙度、修补砂浆的水灰比以及试件的养护条件都会影响修补砂浆与基体间的粘结强度。选取四种含水饱和度(0%、30%、70%、100%)的旧砂浆作为基体,浇筑水灰比为0.4和0.6的新砂浆,试件密封养护28 d,剪切试验结果表明:当新砂浆水灰比为0.6,旧砂浆含水饱和度按照70%、30%、100%、0%的顺序变化时,界面的剪切强度逐渐减小;当新砂浆水灰比为0.4,旧砂浆含水饱和度按照30%、0%、70%、100%的顺序变化时,界面的剪切强度逐渐减小。同时发现,新砂浆水灰比为0.4时的界面剪切强度普遍大于水灰比为0.6的数值。通过切槽法改变旧砂浆的界面粗糙度,然后浇筑水灰比为0.6的新砂浆,试件标准养护。剪切试验结果表明:当旧砂浆界面粗糙时,界面间的剪切强度是旧砂浆光滑时的1.26倍。选取两种含水饱和度(0%、100%)的旧砂浆作为基体,浇筑水灰比为0.4和0.6的新砂浆,分别进行标准养护和密封养护,剪切试验结果表明:在旧砂浆含水饱和度和新砂浆水灰比相同的情况下,标准养护下的界面剪切强度明显大于密封养护下的界面剪切强度。     

埋地管道泄漏内封堵装置设计与研究

针对流体输送埋地管道泄漏问题,设计了一种利用管道机器人携带封堵气囊进行快速应急封堵修复的埋地管道泄漏内封堵装置。采用矩阵变换方法建立了牵引系统驱动轮过弯方程,利用MATLAB软件对过弯方程进行了验证,同时利用ADAMS软件仿真分析过弯路径与驱动轮转角对牵引系统行走速度的影响。研究结果表明:由两个串联封堵器组成的应急封堵系统可满足复杂工况下的管道泄漏封堵要求;牵引系统驱动轮在弯管内部行走时,单轮速度呈周期性变化,但三个驱动轮整体周期运动特性一致;驱动轮转角在25°~40°时,牵引系统行走速度与驱动轮转角成正比,且转角为30°时驱动效果最好。该内封堵装置的结构设计可为管道泄漏应急封堵领域装备的研发提供重要参考。     

破损水文观测孔涌水封堵技术在高河矿的应用

针对高河矿奥灰水文观测孔空水管锈蚀断裂漏水严重的问题,分析了存在的问题,制定了钻孔涌水封堵技术方案及相应的注浆施工工艺,并进行了为期7天的井下试验。封堵注浆压力达到6 MPa,使用注浆水泥50 t,水泥浆液凝固良好,注浆阀门打开后无出水现象。     

The role of an interfacial interpenetrating polymer network formation on the adhesion of resin composite layers in immediate dentin sealing

The aim of this study was to evaluate the influence of chemical and physical processes at the resin-composite and composite-cement interface as a function of the resin composite's water exposure on the bond strength (BS) between these two components. The free-radical concentration was studied using electron paramagnetic resonance (EPR), while the chemical changes at the resin composite's surface were studied using attenuated total-reflection FTIR spectroscopy (ATR-FTIR). The free-radical concentration in the studied samples dropped to 10% in 24 h, indicating that prolonged BS values do not correlate with the free-radical concentration. An alternative bonding mechanism between the resin composite and the composite cement was proposed, based on the formation of an interpenetrating polymer network (IPN) layer at the interface. As proven using ATR-FTIR spectroscopy, changes occurred at the resin composite's surface as a consequence of water exposure, comprising the diffusion of water molecules into the resin composite. These changes reduced the diffusion rate of the composite cement's phosphorus-containing monomers into the resin composite, as shown by the linescan SEM-EDS analysis of phosphorus, thus reducing the thickness of the IPN layer at the interface and consequently reducing the BS between both components.This study reveals that the concentration of free radicals at the surface of the resin composite is only relevant immediately after the polymerisation to the bond strength between the resin composite and the composite cement. Therefore, an alternative explanation is given by applying the theory of the formation of a gradient IPN at the interface between the resin composite and the adhesive cement by changes in the rate of diffusion of the adhesive cement's monomers into the resin composite as a function of the resin composite's exposure to water.     

采油树平板闸阀柔性密封圈结构优化设计

为了提高采油树平板闸阀密封圈的密封性能,在泛塞封的基础上,设计一种密封圈本体唇边开有锯齿状凸起的新型柔性密封结构;运用有限元分析方法模拟密封圈的工作状况,分析柔性密封结构特性参数对密封圈密封性能的影响,获得不同柔性密封圈结构参数下密封面间接触应力分布规律,并对新型密封结构进行优化。结果表明:密封面间最大接触应力随唇边锯齿数量、唇边夹角度数的增大而增大,随唇谷夹角度数的增大而减小;新型密封结构选择锯齿数量为3、唇边夹角为20°、唇谷夹角为30°的特性参数时,其最大接触应力比常规Y形密封圈提高了15倍;新型柔性密封结构的密封圈与阀杆、阀盖壁面间接触应力比常规Y形密封圈有显著提高,提高了密封圈的密封性能。