As always, I am pleased to be here at the National Press Club for my (1) Speech. This is the seventh time I have had the (2) to give this speech, and over the years I have talked about a wide range of issues: (3) , reading, setting high expectations, improving the teaching profession, and (4) the American high school -- to name just a few.
I have just returned from a five-day, (5) tour of schools in rural America. We started in Monroe, Louisiana, and finished (6) later in Paducah, Kentucky. What I noticed most about the trip was the weather. Every time I (7) my Success Express School Bus, the local people who came to greet me (8) that the record for (9) had just been broken in their community. In each place, the temperature was always between (10) degrees.
Now, I have very good people on my staff. But the next time we plan a (11) , I’m going to have a (12) on my staff. I took this bus trip through rural America to make an important point that the (13) of children in our nation’s small towns cannot be ignored. Twenty-five percent of all our school children live in (14) all over America.
When it comes to our children, let’s always remember that children everywhere have (15) and (16) . Yet, schools in small towns too often have to (17) because of limited resources and a (18) . On my trip I put a p focus on the issues that matter in rural America, with a particular emphasis on (19) schools, reducing class size, and overcoming the (20) .

“预应力混凝土连续箱梁桥、混凝土浇筑、振捣、施工预拱度、荷载、管道压浆”案例答案解析题

背景材料：

某沿海大桥是一座跨径为28.5+340.5+28.5m的变截面预应力混凝土连续箱梁桥，分上下两幅，每幅单箱顶宽14.50m，底板宽7m，梁高由支点的2.75m渐变到跨中的1.80m.根据桥位处的地质情况和大桥本身的特点，采用逐段现浇，每段有一超过墩身8.5m的长度，末端浇筑长度为20m.

支架纵梁采用六四军用梁，为减小纵梁在混凝土重量作用下的过大变形，在每个边跨设一排临时支墩，3个主跨各设置两排支墩，支墩均为摩擦桩，卸落设备采用砂箱.在安装模板时，全面计算并设置了预拱度值.为减小支架变形，混凝土分2次浇筑，第一次浇筑底板和腹板，第二次浇筑顶板和翼缘板.为防止桥墩与支架发生沉降差而导致墩顶处梁体混凝土开裂，采用自两边墩台向跨中分段浇筑的方法.因管道较多、钢筋密，决定采用大直径振捣器直接运送混凝土并振捣，以确保有预应力管道下的混凝土密实.混凝土达到设计强度后，张拉预应力筋，按要求和规定压浆.

问题：

1、混凝土浇筑顺序是否合理？请说明理由.

2、混凝土振捣是否合理？为什么？

3、施工单位在计算施工预拱度时，应考虑哪些荷载？

4、如何对管道进行压浆？