基于数值模拟的主动加热FBG法干密度测量技术标定

Calibration of Dry Density Measurement Technique for Actively Heating FBG Method Based on Numerical Simulation

干密度是土的工程性质的重要参数,和土体的物理力学性质紧密相关,干密度的原位测量对保证岩土工程的安全和施工质量有重要意义。主动加热FBG法因其准分布测量、高精度、耐腐、不受电磁干扰等特点成为干密度原位测量可能的重要手段之一,但是测量结果需要进行大量的室内或原位标定实验,经济投入大,耗费时间久。文章采用数值模拟的方法,模拟土体在主动加热FBG法测量干密度过程中的热响应过程,提出了主动加热FBG法的一种新标定方法,可以进行不同含水率下以及不同土类情况下干密度和温度特征值的关系曲线的标定。数值模拟结果与室内试验结果有较好的一致性,提出的数值模型可以还原土体的热响应过程,验证了新标定方法的有效性。

Dry density is very important for soil engineering properties.In-situ measurement of dry density is of great significance to ensure the safety and construction quality of geotechnical projects.The active heating FBG method has become one of the important means for in-situ measurement of dry density because of its quasi-distributed measurement,high accuracy,corrosion resistance,and immunity to electromagnetic interference,etc.However,the measurement results need to be subjected to a large number of laboratory or in-situ calibration experiments,resulting in high costs and prolonged time consumption.In this study,a numerical simulation is used to simulate the thermal response process of the soil during the measurement of dry density by the actively heated FBG method,and a new calibration method of the actively heating FBG method is proposed to obtain the relationship between the dry density and the temperature characteristics value under different water contents and different soil types.The numerical simulation results are in good agreement with the indoor test results,and the proposed numerical model can reappear the thermal response process of the soil,which verifies the validity of the new calibration method.