饱和度对玄武岩微波响应的影响试验研究

岩石的微波处理效果受诸多因素影响，其中水是一种良好的吸波介质，能提高岩石的微波吸收能力。为探索饱和度对微波照射后岩石响应特征的影响效果，以不同饱和度的玄武岩试样为研究对象，以升温特性、波速与孔隙度变化以及动态抗拉强度等为参考指标，开展了3 kW功率微波照射的破岩试验。从细观与宏观角度的分析结果表明：（1）水的存在影响了微波照射过程中岩样的升温特性，照射的前15 s内，饱和度低于75%组明显促进了升温速率，而饱和度达到100%则作用相反，升温速率低于干燥组；15～30 s随着含水率的减少与蒸发吸热，含水试样升温速率降低；30～45 s内水分蒸发完毕，含水试样的升温速率接近干燥试样。（2）饱和度差异导致玄武岩在微波照射后发生不同程度的波速与孔隙率的变化，波速降幅范围为8.18%～17%，孔隙率增长范围为18.71%～43.65%，损伤效果并未随饱和度升高而增强。（3）同样照射条件下，50%饱和度组在蒸汽压力和热应力共同作用下快速达到强度极限，试样直接发生破坏。其余组试样大多未发生明显细观损伤，最终动态抗拉强度差距不明显。

Experimental study on influence of saturation on the microwave response of basalt

The microwave treatment effect of rocks is affected by many factors. Among them, water is a good absorbing medium, and it can improve the microwave absorbing ability of rocks. This study aims at exploring the effect of saturation on response characteristics of rock subjected to microwave irradiation. Tests of 3 kW power microwave irradiation were carried out on basalt samples with different saturations to examine the variations of the heating characteristics, wave speed, porosity change as well as dynamic tensile strength. The test data was analyzed from the meso and macro perspectives. Some findings identified. 1) The water affects the heating characteristics of the rock sample during microwave irradiation. Within the first 15 s of irradiation, the group with saturation lower than 75% obviously promotes the heating rate; when the saturation reaches 100%, the effect is opposite, and the heating rate is lower than that of the dry group；within 15−30 s, the heating rate of the water-containing sample decreases with the decrease of water content and the endothermic heat of evaporation; within 30−45 s, the water evaporation is completed, the heating rate of the water-bearing sample is close to that of the dry sample. 2) The difference in water saturation leads to varying degrees of wave velocity and porosity changes in basalt after microwave irradiation. The wave velocity reduction range is 8.18%−17%, and the porosity growth range is 18.71%−43.65%. The damage effect does not follow the saturation. 3) Under the same irradiation conditions, the 50% saturation group quickly reaches the strength limit under the combined action of steam pressure and thermal stress, and the samples are directly damaged. Obvious mesoscopic damage are not be observed in most of the other groups of samples, and the difference in final dynamic tensile strength is not distinct.