Investigation Of Relationship Of Temperature Field And Stress Field In Non-destructive Testing Of Ancient Earthen Sites

PS material application is more and more widely in the protection of earthen ruins in northwest China arid areas. And a large number of research results have been achieved, such as PS material and mechanism, the micro mechanism, ageing resistance, permeability, pore fractal features and reinforcement technology of the soil mass. But given the fragility of site soil and its irregularity in the shape of appearance, the introduction of infrared thermal imaging non-destructive testing method to evaluate the reinforcement effect of PS is of special significance.Under the background of Jiaohe earthen ruins, study on the relationship of temperature field and stress field by using infrared thermal imaging non-destructive detection technique. The main content and research results are as follows:(1) An experimental installation for determining the thermal conductivity of ruins soil is designed. Adopting the disturbed soil collected from site of Jiaohe Ruins with different physical condition samples are tested for determination of coefficient of thermal conductivity by using infrared thermal imaging detection technique. To verify reliability of this method, coefficient of thermal conductivity of the same soil is measured by using KD2 Pro. The measured value of infrared thermal imaging detection technique is lower, but the gap of two test methods is small. It approves the feasibility to measure coefficient of thermal conductivity of soil by using infrared imaging technique. At the same time, the effect of different dry densities and moisture on coefficient of thermal conductivity of soil is studied. The investigative result show that if the dry density is increased, coefficient of thermal conductivity of soil with constant water content is increased too; if the water content is increased, coefficient of thermal conductivity of soil with constant dry density is increased too.(2) Adopting the disturbed soil collected from Jiaohe Ruins to make soil models, which are reinforced by different concentration of PS, using KD2 Pro and 10 mm micro-penetrometer, the mechanical strength and thermal conductivity of soil models are determined. It is shown that mechanical strength increase and thermal conductivity reduce for PS reinforced soil. Under the condition of the same dosage of PS, the larger the concentration of PS is, the higher the mechanical strength of soil is, but the smaller the thermal conductivity of soil is. Through analyzing the experiment data regression, thermal conductivity and strength has a good linear negative relationship. Finally, explore the alterative mechanism of thermal conductivity of soil in the effect of PS, describe the relationship between thermal conductivity and strength from microstructure mechanism of soil. The relationship above shows that thermal conductivity can be used to evaluate the reinforcing effects of earthen sites.(3) Using finite element analysis software, according to the infrared thermal imager detection technique had been testing boundary temperature of the soil samples, calculate the thermal conductivity. The calculating results agree with reversing results through heat conduction theory. It improves the credibility that the infrared thermal image detection technology is developed for the determination of site soil thermal conductivity.