About Author｜关于作者

Zhang Xiaojun｜张小俊   Zhang Xiaojun, male, Han nationality, born in November 1984 in Qijiang, Chongqing, holds a master's degree. He graduated from China University of Mining and Technology in 2010 and currently works at CQU Construction Engineering Quality Inspection Co., Ltd. He is a senior engineer, Registered Civil Engineer (Geotechnical), Highway and Waterway Engineering Testing & Inspection Engineer, and part-time master's supervisor outside of China University of Mining and Technology. He mainly engages in construction engineering quality inspection, building structure safety appraisal, and technical management work. He has participated in the compilation of one local standard and published more than 10 academic papers. 张小俊，男，汉族，1984年11月生，重庆綦江人，硕士研究生学历，2010年毕业于中国矿业大学，现就职于重庆重大建设工程质量检测有限公司，高级工程师，注册土木工程师（岩土），公路水运工程试验检测师，中国矿业大学校外兼职硕士研究生导师，主要从事建设工程质量检测、房屋结构安全鉴定及技术管理工作，参编地方标准1部，发表学术论文 10余篇。

Book Description｜书籍描述

STUDY ON DIELECTRIC CONSTANT TESTING OF FROZEN SOIL AND GEOLOGICAL RADAR DETECTION TECHNOLOGY｜冻土的介电常数测试与地质雷达检测技术研究   At present, artificial freezing method is the main technique to pass deep alluvium and fracture rock layers. Recently, artificial freezing method were widely used to stratum reinforcement, such as subway by-pass, deep excavation et al.. However, accidents occurred sometimes in artificial freezing engineering, such as the freezing pipe breaking, and supporting structure fracturing. Therefore, it was needed to find a highly efficient, high-precision non-destructive testing method in frozen wall monitoring. The variation law of electromagnetic parameters were first obtained by using Vector Network Analyser(VNA) (0.1~20GHz) for clay, sand of the deep underground freezing soils, and Shanghai gray silty clay. Regression equation of dielectric constant and resistivity were established at different temperature, mass water contant and frequency, which found the basement of   high-precision interpretation of GPR simulation and explora tion. In physical model test, the similarity criteria of GPR exploration were derived in artificial freezing engineering. The physics simulation study can be realized for different soils (clay, sand, and silt) and different freezing method(single, double and three circle pipe). The character of typical target anomalies in artificial freezing engineering, such as freezing pipe and defects, were obtained. The results show that the similarity criteria of electromagnetic field was contradictory in model testing of using prototype materials, electromagnetic field strength was not strictly similar yet. However, the reflecting characters of model target anomalies in GPR profiles are similar with that of prototypes. In numerical simulation, coupling models of freezing temperature field and time-domain transient electromagnetic field were carried out. Firstly, the artificial freezing temperature field(2D) was computed by finite element method(FEM), which could obtain the distribution of freezing temperature field at different freezing time; Then, electromagnetic parameters models were established using the relationship between electromagnetic parameters and temperature; And forward calculation of GPR’s electromagnetic field was carried out by Time-Domain FEM. Furthermore, the research results were used on exploration of several artificial engineerings, such as Shanghai Yangtze River Tunnel connecting passage. These provided an important basis for the safely rapid construction of projects. This issue results have an important theoretical and application value for artificial freezing engineering and permamost region engineering. 人工冻结法是目前国内外广为使用的通过厚表土带和岩石破碎带的施工方法。近年来，被广泛应用到城市地铁、深基坑等领域,然而在实际工程中往往会因为冻结壁整体强度不足或不交圈，造成冻结管断裂、结构物压裂等事故，造成重大经济损失。因此，在冻结工程中急需一套高效、高精度的连续无损检测方法，确定冻结壁的温度、厚度和缺陷分布情况。本书采用矢量网络分析仪（0.1～20GHz），首次获得了深部地层中的粘土、砂土以及上海粉质粘土的电磁参数变化规律，建立了不同温度、不同含水量、不同频率条件下介电常数和电阻率的回归方程，为人工冻结壁的雷达检测提供了依据。在物理模型试验部分，推导了人工冻结工程雷达检测的相似准则，实现了砂土、粉土、粘土等不同土性及对应单圈、双圈、三圈等不同冻结方式条件下的物理模拟研究，获得了人工冻结工程中冻结管、缺陷等典型目标体的雷达图像特征。研究表明，在采用原型材料进行模型试验时，电磁场的相似准则是矛盾的，其电磁场强度并不严格相似，但其反映的目标体的雷达图像特征是相似的。在数值模拟部分，采用有限单元法实现了冻结温度场与时域瞬变电磁场的多场耦合数值模拟。首先采用有限单元法，进行人工冻结温度场的二维（2D）数值模拟，获得了冻结不同时刻的温度场分布状况；进而利用电磁参数与温度相互关系将之转化为电磁参数模型，并进行地质雷达电磁场的2D模型计算，获得了不同土质、不同探测频率、不同冻结时刻的雷达图像特征。进而，将研究成果用于上海长江隧道联络通道的现场实测，并与冻土温度监测和超前预测相印证，为工程等安全快速建设提供了重要依据。本书成果对人工冻结工程和冻土区工程有重要的理论和应用价值。