基于光纤系统的物理相似模型温度分布与演化特征

为减小水分因素引起的模型试验相似误差,提出了用温度特征确定模型干燥过程的干燥时间(判断模型试验开挖)的方法。建立了光纤传感测温系统,提出克里金空间插值法的估值公式计算模型温度,给出物理模型的温度变异函数表达式。开展了3.0 m×1.2 m×0.2 m二维模型和3.6 m×2.0 m×2.0 m三维模型温度监测试验,监测时间分别超过65,310 d,绘制出模型温度分布云图,探讨了模型干燥(试验开挖)的判断方法。研究表明,模型干燥存在水化放热和液-气相态转变的不同过程,模型温度场演化具有明显的阶段特征,最大温差分别为3.0,4.8℃。干燥后期呈现出竖直方向上高下低的温度梯度,水平方向大致相同的特征,其中低温核区下移并消失是判断模型干燥完成的标志,可作为试验开挖的判断指标。二维模型干燥时间为47 d左右,三维模型干燥时间为213 d左右。

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 characteristics.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 monitoring 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 beyond 65 days and 310 days Subsequently,the temperature distribution map of model drying was drawn and the distinguishing 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.