更多"[不定项选择题]试述超声波透射法现场检测基桩完整性原理及现场检测技术。"的相关试题:
[不定项选择题]试述超声波透射法现场检测基桩完整性原理及现场检测技术。
现场测试工作正确的是()。
A.发射和接收换能器分别置于两声测管的同一高度，自下而上，将收发换能器以相同步长(不大于200mm)向上提升，进行水平检测
B.若平测后，存在桩身质量的可疑点，则进行加密平测，以确定异常部位的纵向范围
C.斜测时，发、换能器中心线与水平夹角一般取30°～40°
D.扇形测在桩顶、桩底斜侧范围受限或减小换能器升降次数时采用
[不定项选择题]试述超声波透射法现场检测基桩完整性原理及现场检测技术。
根据《公路工程基桩动测技术规程》)(JTG/TF81-01-2004)规定，关于仪器设备要求正确的有()。
A.声波发射脉冲为阶跃或矩形脉冲，电压最大值不小于1000V
A.换能器沿径向无指向性
B.换能器谐振频率为1kHz～200kHz
C.换能器在1MP
D.水压下能正常工作
[不定项选择题]试述超声波透射法现场检测基桩完整性原理及现场检测技术。
下列结果分析中不正确的表述有()。
A.声速临界值采用混凝土声速平均值与2倍声速标准差之差
A.波幅异常时的临界值采用波幅平均值减6D
B.
C.实测混凝土声速平均值低于声速临界值时，可将其作为可疑缺陷区域
D.当PSD值在某点附近变化明显时，可将其作为可疑缺陷区域
[不定项选择题]试述超声波透射法现场检测基桩完整性原理及现场检测技术。
声波在混凝土传播过程中，当桩身混凝土介质存在阻抗差异时，将产生()造成声波能量的吸收、衰减，通过声学参数或波形变化来检验桩身混凝土是否存在缺陷。
A.反射波、绕射波、折射波
B.声时、波幅变化
C.透射波、吸收波
D.接收波主频变化
[不定项选择题]共用题干
American Dreams
There is a common response to America among foreign writers:the US is a land of
extremes where the best of things are just as easily found as the worst.This is a cliché（陈
词滥调）.
In the land of black and white,people should not be too surprised to find some of the
biggest gaps between the rich and the poor in the world.But the American Dream offers a
way out to everyone.________(1)No class system or government stands in the way.
Sadly,this old argument is no longer true.Over the past few decades there has been a fundamental shift in the structure of the American economy.
The gap between the rich and the poor has widened and widened.________(2)
Over the past 25 years the median US family income has gone up 18 percent.For the
top 1 percent,however,it has gone up 200 percent.Twenty-five years ago the top fifth
of Americans had an average income 6.7 times that of the bottom fifth.________
(3)
Inequalities have grown worse in different regions.In California,incomes for lower
class families have fallen by 4 percent since 1969.________(4)This has led to an
economy hugely in favor of a small group of very rich Americans.The wealthiest 1 percent
of households now control a third of the national wealth.There are now 37 million
Americans living in poverty.At 12.7 percent of the population,it is the highest percentage
in the developed world.
Yet the tax burden on America's rich is falling,not growing.________(5)There
was an economic theory holding that the rich spending more would benefit everyone as a
whole.But clearly that theory has not worked in reality.
________（5）
A.Nobody is poor in the US.
B.The top 0. 01 percent of households has seen its tax bite fall by a full 25 percentage points since 1980.
C.For upper class families they have risen 41 percent.
D.Now it is9.8 times.
E.As it does so,the possibility to cross that gap gets smaller and smaller.
F.All one has to do is to work hard and climb the ladder towards the top.
