岩石与岩体冻融损伤内涵区别及研究进展

Connotation Differences and Research Progress of the Freeze-Thaw Damages of Rock and Rock Mass

岩石与岩体内部结构、空间尺度及裂隙分布形式不同,在冻融循环作用下其损伤劣化机制存在显著差异,损伤评判标准亦有所不同,因此厘清岩石与岩体冻融损伤内涵区别并总结相关研究进展具有重要意义。在内涵方面,岩石损伤主要是内部微小缺陷作用,属于微观层面问题(毫米量级及以下尺度);而岩体损伤则更加关注节理裂隙的影响,属于宏观层面问题(厘米量级及以上尺度)。目前冻融损伤相关研究主要集中在完整岩石块体,对于含有宏观裂隙的岩体研究较少;岩石冻胀是原位水冻胀与迁移水冻胀共同作用的结果,主要从冻胀力与疲劳损伤2个角度进行岩石冻融损伤本构模型的构建研究。未来岩体冻融损伤研究应重点关注裂隙所带来的影响,即从微观尺度入手,利用室内试验探究冻融循环过程孔隙和裂隙内部水分迁移冻胀机制与相互作用规律,结合现场试验与数值模拟研究构建大尺度下岩体冻融损伤本构模型,最终形成寒区岩石与岩体冻融损伤评价体系。

The area of Chinese permafrost accounts for about 21.5 percent of the land area,ranking third in the world,and the permafrost area at high altitude accounts for about 80.6 percent of the permafrost area in China. Under the guidance of the national grand strategy,infrastructure construction in these areas has been greatly developed these years,but at the same time,the special geographical environment of the cold region puts forward a new test for the safety,stability and durability of rock mass engineering. In order to reduce the occurrence of engineering accidents and ensure public safety,it is of great significance to figure out the connotation differences and research progress of the freeze-thaw damages of rock and rock masses.By referring to the latest research results in the field of rock and rock masses freeze-thaw damage,the differences between rock and rock masses freeze-thaw damage are clearly defined,and the research status of freeze-thaw damage of rock and rock masses is systematically summarized and sorted out from three aspects:Physical and mechanical properties,freeze-thaw damage theory,constitutive model.It is found that the freeze-thaw damage mechanisms of rock and rock masses are remarkably different due to the various internal structures,spatial scales and distributions of fractures,and the corresponding criterions for damage evaluations are also different.From the perspective of connotations,the damage of rock results from the formation of microcrack and belongs to the microscopic scope(with a scale of millimeter or less),but the damage of rock masses is mainly influenced by fractures(with a scale of centimeter or more)and falls into the macroscopic scope.The current studies related to the freeze-thaw damages primarily focus on the intact rock blocks,and few researchers investigate the rock masses containing macroscopic fractures.Rock failure is due to the combined action of the frost heaves of in-situ and migratory water,and therefore the constitutive model of rock freeze-thaw damage is mainly built in the perspective of frost heave forces and fatigue damages. In the future,the influences of factures should be pay more attention.Starting from the microscopic scales,the mechanisms of water migrations and frost heaves and the laws of interaction in microcracks and fractures under the process of freeze-thaw cycles should be analyzed by laboratory experiments.Meanwhile,the constitutive model of freeze-thaw damage of the large-scale rock masses should be built by the numerical simulation and field tests.In this way,the evaluation system of freezethaw damage of rock and rock masses in cold regions could be formed.