Optical Diagnostics of Multi-Gap Gas Switches for Linear Transformer Drivers

The trigger characteristics of a multi-gap gas switch with double insulating layers,a square-groove electrode supporter and a UV pre-ionizing structure are investigated aided by a high sensitivity fiber-bundle array detector, a UV fiber detector, and a framing camera, in addition to standard electrical diagnostics. The fiber-bundle-array detector is used to track the turn-on sequence of each electrode gap at a timing precision of 0.6 ns. Each fiber bundle, including five fibers with different azimuth angles, aims at the whole emitting area of each electrode gap and is fed to a photomultiplier tube. The UV fiber detector with a spectrum response of 260-320 nm,including a fused-quartz fiber of 200 μm in diameter and a solar-blinded photomultiplier tube, is adopted to study the effect of UV pre-ionizing on trigger characteristics. The framing camera,with a capacity of 4 frames per shot and an exposure time of 5 ns, is employed to capture the evolution of channel arcs. Based on the turn-on light signal of each electrode gap, the breakdown delay is divided into statistical delay and formative delay. A decrease in both of them, a smaller switch jitter and more channel arcs are observed with lower gas pressure. An increase in trigger voltage can reduce the statistical delay and its jitter, while higher trigger voltage has a relatively small influence on the formative delay and the number of channel arcs. With the UV pre-ionizing structure at 0.24 MPa gas pressure and 60 kV trigger voltage, the statistical delay and its jitter can be reduced by 1.8 ns and 0.67 ns, while the formative delay and its jitter can only be reduced by 0.5 ns and 0.25 ns.     

洛湛铁路清水隧道花岗岩蚀变带地质病害及工程整治

花岗岩蚀变带岩性混杂,结构松散,空间分布无规律性,与围岩间有差异性风化,且地下水相对集中,易造成隧道施工产生塌方冒顶、大变形等病害。本文结合洛湛铁路清水隧道施工中病害的处理措施,对花岗岩蚀变带的工程性质进行了总结和反思。     

郑西高铁K921路基底鼓病害研究

郑西高铁K888+000～K921+250段路堑出现底鼓病害,轨道扣件系统调整余量已近极限,急需查明底鼓病害原因,研究剩余底鼓量和持续时间,以便开展病害整治。本项目研究成果：（1）现场调查排除了堑坡失稳及其他区域地质条件改变引起路基隆起病害的可能性;（2）对现场样品进行膨胀性参数测试,对结果数值进行统计分析,确定底鼓病害由灰土层引起;（3）采用“蔗糖法”测试灰土样品中尚能发生膨胀反应的有效氧化钙含量;（4）采用比对法和代表性现场灰土样浸水试验研究灰土样的剩余上涨量,综合分析认为剩余底鼓量值已不大,可择机进行病害整治;（5）研究成果已得到应用,病害工点已成功治理。本研究在相似铁路、公路路基底鼓病害工点的勘察、设计及治理工作中具有参考价值。