基于核磁共振的地表积雪融化入渗试验模拟

自然条件下岩体的冻融损伤程度往往决定于岩体的含水状态。但以往研究更多的关注岩体冻融的温度条件，而对其湿度条件尤其是自然条件下的吸水过程则鲜有研究。通过自主设计的室内积雪融化入渗实验，模拟自然条件下地表积雪融化下渗的过程。通过核磁共振（NMR）分层含水率测试，对积雪入渗前后试样内部的含水状态进行了实测。实验结果表明：（1）积雪融化速度及融化后入渗速度受到样品孔隙结构的显著影响，开放的宏观节理是融雪融化入渗的理想通道，孔隙率越大积雪融化入渗速率越快，在孔隙率相近的情况下，孔隙的连通性越好积雪融化入渗速率越快；（2）融雪入渗过程中样品内部水分分布不均匀，融雪入渗后样品不同位置的饱和度差异明显；（3）融雪入渗后部分样品的饱和度并没有达到冻融损伤的门槛值。考虑到自然条件下积雪融化入渗条件更为苛刻，岩体的含水状态会成为制约冻融损伤过程的关键因素。

A NMR based experimental simulation of snowmelt infiltrating into bedrock

Frost damage of natural rock is usually controlled by moisture content rather than thermal conditions. However, more attention was paid to the thermal conditions in existing studies, the moisture condition of rocks in natural environments were rarely studied. In this paper, an indoor experiment was designed to simulate the process of surface snowmelt infiltrating into bedrock. The moisture distribution profiles before and after snowmelt infiltration were precisely measured through the layered moisture content tests via nuclear magnetic resonance method (NMR). The results indicate that:(1) The melting rate of snow and infiltrating rate of snowmelt are primarily determined by the pore structure of rock; the open macroscopic fissures is the ideal channel for snowmelt infiltration; larger porosity corresponds to faster snowmelt infiltration; in the case of similar porosities, pore connectivity controls the rate of snowmelt infiltration. (2) Water distribution across the sample is not uniform, water saturation degree at different layers of the sample differs significantly. (3) The overall saturation degrees of some samples when snowmelt infiltration do not reach to the threshold value for frost damage. Considering that the conditions of snowmelt infiltration in natural environments are more rigorous, moisture condition of rock can become a key factor in controlling the occurrence and evolution of frost damage.