基于探地雷达的缺陷岩体注浆效果评价试验研究

发布时间：2018-06-19 00:53

本文选题：探地雷达 + 缺陷岩体　；参考：《中南林业科技大学》2014年硕士论文

【摘要】：探地雷达是一种具有高效、快速、便捷、连续的无损检测物理探测方法,是一种目前先进的高频电磁波勘探技术。由于它对浅层目标体具有良好的探测效果,因而广泛地应用于工程结构检测、工程地质及水文地质勘查、隧道工程超前预报与检测、考古调查以及生态环境检测等方面。由于电磁波传播的高频特性,传播环境条件干扰大,以及探测环境复杂性等,使得探地雷达在进行缺陷及缺陷注浆的探测中存在着不足,例如：数据分辨率不高、雷达图像的识别主要依靠人工识别等。因此,开展岩体缺陷探测及缺陷注浆探测的物理正演模拟工作,研究电磁波在缺陷岩体中的传播规律,有利于对雷达采集数据的分析、雷达图像识别以及对地下岩体结构形态判别的经验积累；通过快速有效地的物理模型试验研究,可进一步提高探地雷达回波信号识别的准确性,对解释和识别地下介质或目标体具有重要意义。本论文通过物理模型试验、数值正演模拟,采用希尔伯特变换和小波变换消噪技术等方面对岩体缺陷及注浆效果探测技术进行了较为系统深入的研究。利用LTD-2100探地雷达系统进行实测以及GprMax2D软件进行仿真实验,利用雷达后处理软件IDSP6.0和数值分析软件MALAB分别选取希尔伯特变换和小波变换消噪的方法进行了试验数据的处理与分析,主要研究内容和成果如下：一、研究内容 (1)以MATLAB数值分析平台,编制程序实现了LTD-2100探地雷达系统数据导入,即原始雷达数据的文件存储中信息以及数据文件*.LTE格式文件的读取,从而可以方便地使得探地雷达数据进行二次开发、分析、处理和成像。 (2)根据电磁波的传播理论,岩体介质中传播的高频电磁波服从麦克斯韦方程组,分析了二维时域有限差分方程,以GprMax2D软件为数值模拟平台,选择与实际探测天线接近的雷达激励源——雷克子波,建立了水、混凝土、湿砂等不同充填介质在岩体缺陷结构中的探地雷达电磁波传播模型。模拟了不同尺度、不同形状、不同填充状态下二维的探地雷达波场,在此基础上研究了不同岩体缺陷及注浆效果对雷达反射(回波)信号的影响。 (3)进行了不同岩体缺陷结构(形状、规模、充填物)传播的物理模型试验,在利用雷达后处理软IDSP6.0进行常规的数据处理,包括增益调节、水平滤波和垂直滤波等的基础上,对雷达数据进行了希尔伯特变换分析,提取了瞬时振幅、瞬时相位和瞬时频率的“三瞬”属性特征,利用属性参数进行了雷达数据分析和解释。 (4)基于探地雷达数据采集信号的非平稳性,以及高频脉冲信号的非线性衰减等特点,对探地雷达回波信号的小波消噪处理技术进行了探索。利用MATLAB软件,研究分析了二维小波变换在探地雷达回波信号处理中的分解、重构和消噪的算法,选取混凝土注浆探测数据进行小波消噪,分析结果与希尔伯特变换对比,研究两方法的实用性。二、主要成果 (1)同一探测环境下,以水、混凝土、干砂、湿砂、淤泥和粘土为充填介质,进行缺陷岩体填充程度注浆模拟。研究表明：满充填程度时,水、湿砂、淤泥和粘土介质充填时隐约见到模糊的顶角波形,湿砂和淤泥的深层信号形成较强的二次绕射波,混凝土和干砂较难分辨；其原因是充填介质与探测环境的相对介电常数相差越小,波形图越难识别。半充填条件下,波形剖面都能很容易的辨别缺陷顶角的小波形,对比深部波形信息,发现水、湿砂、淤泥和粘土充填比混凝土、干砂子和空气充填含有更强多次的绕射波。 (2)不同探测环境下的数值模拟,研究发现：满填条件下,空气、水、混凝土、湿砂、淤泥和粘土含有的绕射波信息由多到少的探测环境是干燥环境、分层环境和潮湿环境,干砂则相反；半充填条件下,分辨程度由易到难的探测环境是潮湿、分层和干燥,各种环境条件下水、湿砂、淤泥和粘土较易分辨。 (3)利用不同形状、充填程度的混凝土数值模拟,进行了理论探测和现场试验探测对比模型研究,分析表明现场试验模拟理论满注浆和半注浆的半圆形、三角形存在缺陷时,雷达波形有较明显差异。 (4)试验数据处理分析表明：缺陷岩体以水、湿泥、湿砂、干砂子填注。可以分析其属性参数：瞬时振幅图形,可利用强白区和分层突变线进行判别半注浆和满注浆。若有强白区或分层突变线,表示为缺陷岩体半注浆或未注满；若没有分层突变线存在,表明注浆探测结果为满注。 (5)研究表明：半注浆或未注满时能形成分层突变线但没有强白区,这是由于充填混凝土未振捣压实,注浆表层面没有形成薄水膜造成；满注浆时明显发现有矩形白区域,由于充填混凝土振捣压实、满注流浆,注浆表层形成了薄水膜造成；建议：注浆完成后的检测应尽早进行。根据这一特性结合探测现场环境和地质资料可以进行施工现场注浆效果探测和评价。这为运用探地雷达进行注浆效果现场监测提供了技术。 (6)研究表明瞬时振幅强弱与衰减的性质较容易识别介质层位；瞬时相位剖面上的同相轴连续性较易判别缺陷岩体顶面位置,利用其深层信号特征较易判别岩体注浆程度；利用瞬时频率特征分析介质变化性质难以判别缺陷形状,但结合瞬时振幅特征可以共同判定缺陷岩体注浆效果。综合“三瞬”属性特性分析,可知：雷达探测注浆效果的敏感性因子是水,包含充填介质的含水率,含水量高则探测结果敏感。 (7)利用小波二维窗口,选取dbl小波函数,以Ievel2为层数,分解并进行消噪处理,选用软阈值和尺度白噪声,分别从水平方向、斜线方向和垂直方向进行量化系数调试,消噪、重构,可以从Residuals中获取了清晰可分辨的岩体缺陷形状及缺陷注浆效果图。 (8)小波消噪和希尔伯特变换对比分析研究表明：利用二维小波变换的雷达回波信号消噪方面有较好的效果,较易识别缺陷岩体形状及缺陷顶面、底面位置,比希尔伯特变换更为精细、直观地反映缺陷岩体及其缺陷混凝土注浆效果,同时将倒三角形和半圆形容器注浆时形成的两个小缺陷孔洞波形反映出来,但在有缺陷孔洞探测条件下两形状容器未满填形状不易辨别。
[Abstract]:Ground penetrating radar is a kind of advanced high frequency electromagnetic wave exploration technology , it is a kind of advanced high frequency electromagnetic wave exploration technology . Because it has good detection effect on shallow target body , it is widely used in engineering structure detection , engineering geology and hydrogeologic exploration , advanced prediction and detection of tunnel engineering , archaeological investigation and ecological environment detection .
Through the rapid and effective physical model test research , it can further improve the accuracy of the detection of the radar echo signal , which is of great significance to the interpretation and identification of the underground medium or target body .

In this paper , through physical model test , numerical forward modeling , using Hilbert transform and wavelet transform de - noising technique , this paper makes a systematic and deep research on the technology of detecting the defects and grouting effect of rock mass . By using LTD - 2100 ground penetrating radar system and simulation experiment with GprMax2D software , this paper deals with the processing and analysis of the test data by using the radar post - processing software IDSP6.0 and the numerical analysis software MALAB . The main research contents and results are as follows :

I . Contents of the study

( 1 ) Based on the MATLAB numerical analysis platform , the data import of the LTD - 2100 ground penetrating radar system is realized by the programming procedure , that is , the information in the file storage of the original radar data and the data file * . The reading of the LTE format file can facilitate the secondary development , analysis , processing and imaging of the ground penetrating radar data .

( 2 ) According to the propagation theory of electromagnetic wave , the high - frequency electromagnetic waves propagating in the rock mass are subject to Maxwell ' s equations , the finite difference equation of the two - dimensional time domain is analyzed , and the electromagnetic wave propagation model of ground penetrating radar in the rock mass defect structure is selected by using the GprMax2D software as the numerical simulation platform .

( 3 ) The physical model test of different rock mass defect structure ( shape , scale , filling ) propagation is carried out . On the basis of using radar post - processing soft IDSP6.0 to carry out routine data processing , including gain adjustment , horizontal filtering and vertical filtering , Hilbert transform analysis is carried out on radar data , instantaneous amplitude , instantaneous phase and instantaneous frequency ' s ' three transient ' attribute characteristics are extracted , and the attribute parameters are used for radar data analysis and interpretation .

( 4 ) Based on the non - stationarity of ground penetrating radar data acquisition signal and the nonlinear attenuation of high frequency pulse signal , the wavelet de - noising processing technique of ground penetrating radar echo signal is explored .

II . Main results

( 1 ) In the same detection environment , water , concrete , dry sand , wet sand , sludge and clay are used as filling medium to simulate the filling degree of defective rock mass .
The reason is that the smaller the relative dielectric constant of the filling medium and the detection environment , the more difficult it is to identify the waveform chart . Under the semi - filling condition , the waveform profile can easily distinguish the small waveform of the top angle of the defect and compare the deep waveform information . It is found that the water , the wet sand , the sludge and the clay are filled more than the concrete , the dry sand and the air are filled with more intense diffraction waves than the concrete , the dry sand and the air .

( 2 ) Numerical simulation under different detection environment , it is found that under the condition of full filling , air , water , concrete , wet sand , sludge and clay contain the diffraction wave information from many to less detection environment is dry environment , layered environment and moist environment , dry sand is the opposite ;
Under the condition of semi - filling , the detection environment is moist , layered and dry , and water , wet sand , sludge and clay are more easily distinguished in various environmental conditions .

( 3 ) Based on the numerical simulation of concrete with different shapes and filling degree , a comparative model of theoretical detection and field test is carried out . The results show that the simulation theory of field test is full of semi - circular and triangular shape of grouting and semi - slip casting , and the radar waveform has obvious difference .

( 4 ) The analysis of the data shows that the defect rock mass is filled with water , wet mud , wet sand and dry sand . The attribute parameters of the defect rock mass can be analyzed : the instantaneous amplitude graph , the strong white area and the layered mutant line can be used to judge the semi - grouting and full grouting .
If there is no stratified mutation line , it indicates that the grouting detection result is full .

( 5 ) The research shows that the layered abrupt line can be formed without strong white area when the semi - slip casting or the filling is not full , because the filling concrete is not vibrated and compacted , and the surface of the grouting surface layer does not form a thin water film ;
When full slip casting , the rectangular white area is obviously found , which is caused by the filling concrete vibrating compaction , the full injection of the slurry and the formation of thin water film on the surface layer of the slip casting ;
It is suggested that the detection of grouting effect should be carried out as soon as possible after grouting is completed . According to this characteristic , the site environment and geological data can be used for detecting and evaluating the grouting effect on the construction site . This provides a technique for field monitoring of grouting effect using ground penetrating radar .

( 6 ) The study shows that the nature of the instantaneous amplitude and attenuation is easier to identify the media horizon ;
The continuity of the same - phase axis on the instantaneous phase profile is easy to distinguish the position of the top surface of the defective rock mass , and it is easy to judge the grouting degree of the rock mass by using its deep signal characteristics ;
It is difficult to distinguish the defect shape with the characteristic of instantaneous frequency characteristic , but it can be used to determine the grouting effect of the defective rock mass in combination with the instantaneous amplitude characteristic .

( 7 ) using the wavelet two - dimensional window , selecting dbl wavelet function , taking Ievel2 as the number of layers , decomposing and carrying out denoising treatment , selecting soft threshold and scale white noise , performing quantization coefficient debugging , noise elimination and reconstruction from the horizontal direction , the oblique line direction and the vertical direction respectively , and obtaining clear and distinguished rock mass defect shapes and defect grouting effect graphs from Residences .

( 8 ) The comparison and analysis of wavelet de - noising and Hilbert transform shows that the two - dimensional wavelet transform radar echo signal denoising method has better effect , it is easier to identify the shape of the defective rock body and the top surface and the bottom surface of the defect , and can directly reflect the grouting effect of the defective rock mass and the defect concrete , and simultaneously reflect the two small defect hole waveforms formed when the inverted triangle and the semi - circular container are injected , but the shape of the two - shape container under the detection condition of the defective hole is not easy to distinguish .
【学位授予单位】：中南林业科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU195.1;TU45

【参考文献】