Limiting drainage criterion for groundwater of mountain tunnel

Large amount of groundwater discharging from tunnel is likely to cause destruction of the ecological environment in the vicinity of the tunnel, thus an appropriate drainage criterion should be established to balance the tunnel construction and groundwater.To assess the related problems, an limiting drainage standard ranging from 0.5 to 2.0 m3/（m·d） was suggested for mountain tunnels based on survey and comparative analysis. After that, for the purpose of verifying the rationality of the standard, a calculated formula for dewatering funnel volume caused by drainage was deduced on the basis of the groundwater dynamics and experience method.Furthermore, the equation about the relationship between water discharge and drawdown of groundwater table was presented. The permeability coefficient, specific yield and groundwater table value were introduced, and then combined with the above equation, the drawdown of groundwater table under the proposed limiting drainage criterion was calculated. It is shown that the proposed drainage standard can reach the purpose of protecting ecological environment under the following two conditions. One is the permeability coefficient ranges from 10-4 to 10-5 m/s and the specific yield ranges from 0.1 to 0.001. The other is the permeability coefficient varies from 10-6 to 10-8 m/s and the specific yield varies from 0.1 to 0.01. In addition, a majority of common geotechnical layers are involved in the above ranges. Thus, the proposed limiting drainage standard which ranges from 0.5 to 2.0 m3/（m·d） for mountain tunnel is reasonable.     

铁电薄膜平均极化性质的研究

是在热力学唯象理论的框架下,研究由两种铁电材料组成的铁电双层膜系统的极化性质.通过引入的两个参量:参量(描述铁电双层膜系统中两种铁电体的物理性能差异)和参量(描述铁电双层膜系统两种铁电体相变温度的差异),研究了不同温度和不同界面耦合系数条件下,铁电双层膜系统平均极化随这两个参量的变化情况.研究表明:参量增大时,铁电双层膜系统的平均极化随之增大.当取固定值时,平均极化随界面耦合系数增大而增大;随着温度t、参量的增大而减小.参量增大时,铁电双层膜系统的平均极化减小.当参量取固定值时,平均极化随着温度t的增大而减小;随着参量、界面耦合系数的增大而增大.     

溶洞对隧道(洞)稳定性影响的数值试验及现场监测分析

依托武都水库的导流隧洞工程建设,就既有岩溶溶洞对隧道(洞)稳定性的影响进行了跟踪现场施工的动态监测及数值模拟分析,就不同位置及尺寸的既有溶洞对隧道(洞)围岩受力、变形以及支护结构的受力特性的变化进行了深入研究.既有溶洞影响的数值模拟和现场监测分析表明:受顶部既有岩溶溶洞的影响,隧道(洞)围岩的变形特性明显不同于无溶洞时的变形特性,其围岩超前掌子面的先期变形量增加,即围岩位移具有明显的超前释放性.就变形量而言,当既有溶洞的尺寸大于隧洞最大跨度时,既有顶部溶洞将引起隧道(洞)顶拱沉降位移的减小,而当既有溶洞尺寸大于隧道(洞)的最大尺寸时,隧道(洞)顶拱位移反而增加.同时,既有顶部溶洞将引起隧道(洞)水平收敛位移的增加,且位移的增加量随着既有溶洞尺寸的增加而随之增加.隧道(洞)边墙附近的既有侧边溶洞的出现将引起隧道(洞)水平收敛位移的增加,且位移的增加量随着既有溶洞尺寸的增加而增加.就支护结构受力特性而言,隧道(洞)边墙附近的既有溶洞的存在造成隧道(洞)近溶洞一侧喷层轴力的减小,而远离溶洞一侧喷层轴力的增加.     

层状黄土区域地铁隧道变形模拟分析

为解决层状黄土地区地铁隧道的安全施工,采用现场量测与Rocscience软件模拟分析相结合的方法,研究了全断面开挖过程中地铁隧道围岩的稳定性问题。研究结果表明,采用软件分析的结果与现场量测的结果基本一致,在隧道中心线两侧均出现了显著的沉降现象,由于地铁下腹地层为粉砂,所以开挖的隧道要及时闭合,并且要布置仰拱或是管片整体支护。     

高速PIV布撒技术的改进研究

基于上海交通大学高超创新实验室现有技术,为发展高速PIV技术而改进开发了高速PIV粒子布撒系统。针对原有系统经常无法有效布撒粒子的缺陷,从系统中的管道、高压气体、喷嘴等几个方向下手进行改造,设计了新的高速PIV粒子布撒系统。对管道进行了软管化设计,高压气体采用干燥的氮气,喷嘴则设计成能在罐体中产生旋流的结构。对于这些改造进行了分析和实验测试,证明了这些改造能加强布撒粒子的效果。最后提出了这套系统可以继续改进的一些方向。     

长泄洪洞模型糙率修正方法研究

针对长泄洪洞在小比尺物理模型壁面糙率不相似问题进行理论分析和试验研究。通过合理的技术方案和手段在不改变泄洪洞位置与原河道相互关系的前提下,可以在小比尺物理模型上实现泄洪洞出口流速和流量的相似。研究表明,本方法适用于有压接无压和明流泄洪洞,很好的解决了在小比尺模型上长泄洪洞出口挑流水力特性及下游冲刷特性的模型相似性难题,实测结果与理论分析结果符合良好。     

Piezo/pyro/photo-catalysis activities in Ba0.85Ca0.15(Ti0.9Zr0.1)1-xFexO3 ceramics

Ba_0.85Ca_0.15(Ti_0.9Zr_0.1)_1-xFe_xO₃ (x = 0, 0.5, and 1%) ceramics were studied for piezocatalysis, photocatalysis, and pyrocatalysis using dye degradation in the simulated wastewater. The effect of electrical poling was also performed and found a significant impact of poling on all three catalytic reactions. Fe decreased the optical bandgap of Ba_0.85Ca_0.15Ti_0.9Zr_0.1O₃ (BCZTO) to the visible region. Bandgap for x = 0, 0.005, and 0.01 was found to be 3.14 eV, 2.75 eV, and 2.61 eV, respectively. Interestingly, visible light photocatalytic activity was observed after Fe inclusion in BCZTO lattice. These compositions have also demonstrated dye degradation under ultrasonication (piezocatalytsis) and during temporal temperature change (pyrocatalysis). Results indicate promising multicatalysis in BCZTO ceramics which can be tuned using Fe substitution.     

Effect of poling on piezocatalytic removal of muti-pollutants using BaTiO3

The BaTiO₃ powder was prepared via a solid-state reaction route. It was studied for the degradation of bacterial cells, dye, and pharmaceuticals waste using ultrasonically driven piezocatalytic effect. The bacterial catalytic behavior of poled BaTiO₃ was remarkably increased during ultrasonication (10% E coli survival in 60 minutes). The structural damages were illustrated using scanning electron micrographs of bacterial cells which demonstrated morphological manifestations under different conditions. Methylene blue (MB dye), ciprofloxacin and diclofenac were also cleaned using the piezocatalytic effect associated with the poled BaTiO₃ powder. Around 92, 85, and 78% of degradations were observed within 150 minutes duration for methylene blue, ciprofloxacin, and diclofenac, respectively.     

弛豫铁电体Pb(Mg1/3Nb2/3)O3-PbTiO3的相变

测量了(1-x％)镁铌酸铅-x％钛酸铅(1≤X≤11)(简称PMNTx)陶瓷样品的介电常数、内耗和Young’s模量．观测到在Tm温度附近，即在介电常数达到最大值时，出现一个内耗峰，并且模量发生软化．这反映了极化纳米微畴的弛豫．对于PMNTx(5≤x≤11)的样品，在Tm温度以下的某个温度出现附加的内耗峰和Young’s模量的异常，表明样品中发生了自发的弛豫铁电到铁电(简称R-F)的相变，对R-F相变的机制进行了讨论．     

电场、残余应力和介质对PZT-5H铁电陶瓷压痕裂纹扩展的耦合作用

通过在硅油中加恒电场实验,研究了PZT-5H铁电陶瓷Vickers压痕裂纹的扩展行为,探讨了电场、残余应力以及介质间的耦合作用.结果表明,残余应力不足以使压痕裂纹在硅油中发生滞后扩展,只有外加恒电场E>0.2 kV/cm,电场、残余应力和介质的耦合才能使压痕裂纹在经过一个孕育期tp后发生滞后扩展.由于有效应力强度因子随裂纹扩展而下降,故压痕裂纹扩展10-30 μm后就将止裂.压痕裂纹在硅油中滞后扩展的门槛电场强度EDp=0.2 kV/cm.如外加电场大于临界电场Ep=5.25 kV/cm,电场和残余应力的耦合可使压痕裂纹瞬时扩展;保持恒电场,裂纹能继续扩展,然后止裂.如外加电场大于12.6 kV/cm,不需要残余应力协助,电致裂纹也能在光滑试样上形核、长大、连接,导致试样断裂.试样发生电致滞后断裂的门槛电场EDF=12.6 kV/cm,发生瞬时断裂的临界电场EF=19.1 kV/cm.