Temperature distribution and its evolution characteristics of physical similarity model by optical fiber sensing system

In order to reduce errors that are caused by moisture content changing during physical model simulation tests,a method is proposed for determining the model’s drying process time using temperature-distribution characteris- tics. A fiber optic temperature-sensing system is used to measure temperature distributions within the physical model. A Kriging space interpolation formula is presented to calculate temperature values between the measured temperature locations and a function expressing the variation of temperatures in the physical model is given. Temperature monito- ring experiments of model drying process were carried out in a two-dimensional model with the size of 3. 0 m×1. 2 m× 0. 2 m and a three-dimensional model with the size of 3. 6 m×2. 0 m×2. 0 m,and the monitoring time were each be- yond 65 days and 310 days Subsequently,the temperature distribution map of model drying was drawn and the distin- guishing method of model drying completing was analyzed. The results of these tests show that the drying process in the physical model consists of hydration heat release and liquid-gas phase state change,and found a maximum temperature difference of 3. 0 ℃ and 4. 8 ℃ for the two-dimensional and three-dimensional models,respectively. In the later stage of the drying process,the vertical temperature gradient presents a high and low form model’s up to down,and the horizontal direction is approximately the same form model’s right to left. The nucleus of the low temperature zone moved downward and then disappeared signaling the completion of the drying process,and thus can be used as the judgment of a model excavation experiment. The drying time of two-dimensional model is about 47 days in the winter season,and the drying time of the three-dimensional model is about 213 days in the spring and summer seasons.