高速公路雷达探测资料分析

解释结果
EZ Tracker智能识别模式
现场打孔
硬件方面
为什么出现错刺现象?
• • • • • 仪器安装的关键 天线地面距离地面高度范围:45厘米 天线底面与地面平行 这个要求比较高, 常见问题表现如下:
• 天线支架非水平, • 天线4个角不在一个水平面上 • 测试前后天线支架的稳固性
硬件方面
Antenna Calibration file
Height variations are recorded along with corresponding metal plate amplitude
“Bumper Jump”
Bumper Jump file
斜坡文件
A-1
B-1
A-2
Ground Coupling
Layer Interface
Layer Interface
Reflections are produced when the pulse encounters a material with different dielectric constant Dielectric Constant: Air = 1 Asphalt = 3-5 Concrete = 6-8
Should not be seen in time window
(a) Example of incorrect Signal Position
Pavement surface reflection
Portion of direct-coupling that must be seen in time window
“Bumper Jump”
Bumper Jump file
Position Correction: -97 ns Range: 12 ns
Position Correction -96 nS
Position Correction -90 nS
Data Collection Concerns
(1)Make sure the correct portion of the direct-coupling is located within the time window.
公路雷达测试原理示意图
How does GPR work?
We record the two way travel time and the amplitude of the reflection
RoadScan GPR System How does it work?
Antenna
Direct Coupling
Thickness = (2WTT x velocity)/2
空气耦合天线标定
• • • • 选择 1.2x1.2 米 金属板 足够大 金属板位于天线正下方 金属板与天线中心重合 确保3米范围内没有电磁设备干扰，除了测量 车本身。
地质雷达工作原理--路面雷达理论依据
An antenna calibration file is collected using a metal plate as a perfect reflector
Position -97.7 nS
软件方面
铁板文件首波错误
实际资料
软件方面
确保直达波记录在扫描窗口内
可接受的信号位置 (full positive lobe of wave in window) 不可接受的信号位置 (a portion of the positive lobe of wave not recorded)
空气耦合天线探测资料分析
劳雷公司 2007年1月
测量
空气耦合天线安装工作照片
• • • • 天线安装在汽车之前 天线安装在汽车之后 天线安装支架组装方法 天线安装，技术参数
支架加固
DMI安装步骤和工作照片
空气耦合天线工作原理
地质雷达信号
地质模型 数学模型 脉冲 ricker子波
Pavement layer velocities are calculated based on the pavement reflection and the metal plate reflection. (Equation above assumes no separation distance between transmit and receive antennas. Actual equation used for antennas requires finding the roots of a 4th order polynomial equation.)
错刺现象原因:硬件方面
天线支架高度
硬件方面
硬件方面
错刺现象原因:硬件方面
错刺 问题
硬件方面
解决方案:天线支架安装建议
硬件方面
GSSI雷达的DMI测距系统
软件方面
为什么出现错刺现象?
• 首波问题 • 首波不完整，造成处理结果出现明显的 错刺现象。 • 铁板文件 • 实际测量文件 • 铁板文件和实际测量文件首波不一致， 造成比对错误 • 仪器加热时间不充足，导致首波不稳定
VL = velocity of layer (in/ns or m/ns) Ap= Amplitude of pavement reflection Am= Amplitude of metal plate reflection VAIR = propagation velocity in air 11.811 in/ns or 0.3 m/ns
Low Resolution High Depth Penetration
空气
沥青或混凝土
基层
底基层
路面层反射示意图
H=C*T/2 H=45cm C=30cm/ns
T=3ns
参数设置
• 测量仪器
• 测量主机
• 测区参数
• • • •
• • • •
测量对象:config 天线选择:config type 测量速度:scans/sec 测点密度:scans/m
Antenna Frequencies (in air)
2 GHz 1 GHz 400 MHz 200 MHz
0.5 ns (5.9 in) 1 ns (11.8 in) 2.5 ns (29.5 in)
5 ns (59 in)
High Resolution Low Depth Penetration Antennas may be Ground Coupled or Air Coupled
实际资料
软件方面
实际测量资料--首波不完整
软wenku.baidu.com方面
地质雷达工作原理--路面雷达理论依据
VAIR(1 Ap ) Am VL (1 Ap ) Am
VL = velocity of layer (in/ns or m/ns) Ap= Amplitude of pavement reflection Am= Amplitude of metal plate reflection VAIR = propagation velocity in air 11.811 in/ns or 0.3 m/ns
RoadScan GPR System How does it work?
An antenna calibration file is collected using a metal plate as a perfect reflector
Antenna Calibration file
Height variations are recorded along with corresponding metal plate amplitude
Thickness = (2WTT x velocity)/2
Calibrate the Horn Antenna
• Place a 1.2x1.2 metal plate beneath the horn antenna. Make sure it is centered under the antenna and make sure there is 3 m (10 ft) of clear space around the antenna (except for the mounting vehicle)
h:地层底界面深度(m) t:电磁波传播双程时间(ns) c:电磁波在空气中的传播速度(m/ns) v:电磁波在材料中的传播速度(m/ns) ε:材料的介电常数 εr：材料的相对介电常数
反射波极性:正波,负波
负波
正波
** A positive polarity reflection occurs when the layer beneath the interface possesses a propagation velocity less than the layer above the interface. The converse is true for a negative polarity reflection.
• 数据采集期间，记录2米 范围内任何电磁信号特征 • 相邻车道汽车干扰
相邻车道汽车干扰
多次反射，白-黑-白
Strong ringing band here
After applying ringdown removal filter, ringing band removed
xianshi
position首波/信号位置ns range记录长度 gain增益 FIR filter滤波范围
• 天线参数
参数要求
• 信号位置--首波position(ns) • 记录长度--range(ns)
RoadScan GPR System How does it work?
VAIR(1 Ap ) Am VL (1 Ap ) Am
(b) Example of Correct Signal Position
Having saved projects on the SIR-20 will prevent positioning problems
首波错位
• 地面反射波 • 地面反射波同相轴错断 • 地面反射波校准（水平）
地层底界面深度计算
检测结果
自动增益处理前
自动增益处理后
GPR and FWD Integration
Short run GPR file - raw data 10 scans/ft
Pavement surface
Bottom of asphalt
EZ Tracker
Automatic macro process applies calibration file and opens EZ Tracker
Simple point & click technique - Single click to undo layer picking
7米电缆固定
测点：Scans/m
10 Scans/m
5 Scans/m
2.5
1
测点：Scans/m – 管道
20 Scans/m
10 Scans/m
5
数据采集注意事项
Pavement layer velocities are calculated based on the pavement reflection and the metal plate reflection. (Equation above assumes no separation distance between transmit and receive antennas. Actual equation used for antennas requires finding the roots of a 4th order polynomial equation.)
钻孔资料
RoadScan GPR System Working with results
The .LAY file is a generic comma delimited ASCII file that is easily imported into Excel and a variety of other software programs