问题 问答题 论述题

线路大中修纵断面设计中对坡段长度及相邻坡段的连接有哪些规定?

答案

参考答案:

(1)应设计长坡段V允许速度>200km/h的线路最小坡段长度不应小于800m,特别困难条件下最小坡段长度不应小于600m,且不得连续使用;200km/h≥V允许速度>160km/h的线路最小坡段长度不应小于600m,特别困难条件下最小坡度长度不应小于400m;其他线路坡段长度不应小于该区段到发线有效长度的一半,个别困难地段也不应小于200m。最小坡段长度不宜连续使用2个以上。

(2)相邻坡段的连接,应按原线路标准设计为抛物线型或圆曲线型竖曲线

①V允许速度≤160km/h的线路,采用抛物线型竖曲线时,若相邻坡段的坡度代数差大于2‰,应设置竖曲线。20m范围内竖曲线的变坡率,凸形不应大于1‰,凹形不应大于0.5‰。采用圆曲线型竖曲线时,若相邻坡段的坡度代数差大于3‰,应设置竖曲线。竖曲线半径应为20000~10000m,困难地段不应小于5000m。

②160km/h<V允许速度≤200km/h的线路坡度代数差大于等于1‰,应设置圆曲线型竖曲线,竖曲线半径不应小于15000m,且长度不应小于25m;V允许速度>200km/h的线路,竖曲线半径不应小于20000m。

单项选择题

Millions of Americans and foreigners see GI.Joe as a mindless war toy, the symbol of American military adventurism, but that’ s not how it used to be. To the men and women who (1) in World War I1 and the people they liberated, the GI. was the (2) man grown into hero, the pool farm kid torn away from his home, the guy who (3) all the burdens of battle, who slept in cold foxholes, who went without the (4) of 1hod and shelter, who stuck it out and drove back the Nazi reign of murder. This was not a vohmteer soldier, not someone well paid, (5) an average guy, up (6) the best trained, best equipped, fiercest, most brutal enemies seen in centuries.

His name is not much. GI. is just a military abbreviation (7) Govermnent Issue, and it was on all of the article (8) to soldiers. And Joe A common name for a guy who never (9) it to the top. Joe Blow, Joe Magrae... a working class name.The United States has (10) had a president or vieepresident or secretary of state Joe.

GI. Joe had a (11) career fighting Geman, Japanese, and Korean troops. He appears as a character, or a (12) of American personalities, in the 1945 movie The Story of GL Joe, based on the last days of war correspondent Ernie Pyle. Some of the soldiers Pyle (13) portrayde themselves in the fihn. Pyle was famous for covering the (14) side of the warl, writing about the dirt-snow-and-mud soldiers, not how many miles were (15) or what towns were captured or liberated. His reports (16) the "willie" cartoons of famed Stars and Stripes artist Bill Maulden. Both men (17) the dirt and exhaustion of war, the (18) of civilization that the soldiers shared with each other and the civilians: coffee, tobacco, whiskey, shelter, sleep. (19) Egypt, France, and a dozen more countries, G. I. Joe was any American soldier, (20) the most important person in their lives.

(10)()

A.ever

B.never

C.either

D.neither

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