瞬态高温热冲击下岩石传热规律试验研究

Experimental Study on Heat Transfer Law of Rock Under Transient High-Temperature Thermal Shock

为探究岩石在瞬态高温热冲击下内部热量的传递规律及热应力分布规律,通过对花岗岩、石灰岩、砂岩进行高温油浴条件下的瞬态高温热冲击试验,测定不同时刻岩石内温度及温度梯度分布。结果表明:瞬态高温热冲击下岩石内温度变化过程分为快速升温、缓慢升温、温度稳定3个阶段,温度梯度变化表现为先快速增大后缓慢减小至0的过程;受流体渗透的影响,热冲击过程中孔隙率较大的砂岩整体导热效率较空气中常温状态下提升26%以上;不同种类岩石的温度场及温度梯度场具有类似分布及演变规律,温度场呈胶囊状分布,温度梯度场呈条带状分布;瞬态高温热冲击下岩石内热应力峰值出现在100 s(快速升温阶段内)左右,此时岩石更易发生热损伤,且损伤区域集中在靠近试样边界的条带状范围内。

To explore the internal heat transfer law and thermal stress distribution law of rock under transient high-temperature thermal shock,the transient high-temperature thermal shock test under high-temperature oil bath condition was carried out on granite,limestone and sandstone,and the temperature and temperature gradient distribution in rock at different time were measured.The results show that the temperature change process in the rock under transient high-temperature thermal shock is divided into three stages:rapid temperature rise,slow temperature rise and temperature stability.The temperature gradient change shows a process of rapid increase and then slow decrease to 0.Due to the influence of fluid penetration,the overall thermal conductivity of sandstone with large porosity during thermal shock is increased by more than 26%compared with that at room temperature in air.The temperature field and temperature gradient field of different kinds of rocks have similar distribution and evolution law.The temperature field is distributed in capsule shape,and the temperature gradient field is distributed in strip shape.The peak value of thermal stress in the rock under transient high-temperature thermal shock occurs at about 100s(in the rapid heating stage).At this time,the rock is more prone to thermal damage,and the damage area is concentrated in the banded range near the sample boundary.