寒区岩质散体冻胀裂解孕育排土场灾变机理及干预机制研究

Compared with the conventional dump, dump in cold religion have been subjected to the effects of freezing-thawing cycles. As rock mass of dump underwent effect of freezing-thawing cycles have been subjected to constant frost heaving, frost cracking, weathering and crushing, thus the original particle size and mechanical properties of the dump changed, as a consequence, it is easy to induce catastrophe in the dump. Therefore, it is of great significance to carry out research on the catastrophic mechanism and intervention mechanism of rock dump in the cold region.In this program, indoor rock mechanics test, similar model test and numerical calculation are going to be adopted as research methods. By means of multi-disciplines intersection, theoretical analysis and numerical calculation based on peridynamics, this research is going to study the mechanics characteristics, the cracking and frost heaving mechanism and the evolutionary process of rock mass under coupled effect of cyclic freezing-thawing cycles and stress to acquire the distribution law of frost heaving force in and between granular media under cyclic freezing-thawing conditions, to construct the constitutive equation of granular media considering effect of local fragmentation, medium migration and interaction, and to establish multi-scale peridynamics model of granular media. Over all, this program aims at revealing the catastrophic mechanism induced by degeneration effect of rock mass and catastrophe intervention of damp made of cracked rock mass under effect of freezing-thawing cycles, to provide a theoretical basis for the stability analysis of the dump and the development of resources in cold area.

和普通排土场相比，寒区排土场长期遭受冻融循环作用的影响，排土场中的松散岩体不断冻胀、裂解、风化、破碎，改变了排土场原有的颗粒级配和力学特性，容易诱发排土场灾变，因此开展寒区岩质散体冻胀裂解孕育排土场灾变机理及干预机制研究具有重要意义。本研究通过室内岩石力学试验、相似模型试验和数值计算相结合的研究方法，通过多学科交叉、理论分析和近场动力学数值计算等技术手段，研究冻融循环和应力耦合作用下岩质散体力学特性、冻胀裂解规律和及其演化过程，获取冻融循环条件下多介质散体间冻胀力的分布规律；建立考虑局部破碎、介质迁移与相互作用的散体介质本构力方程和多尺度近场动力学模型，揭示冻融循环作用下岩石破碎退化效应诱发排土场灾变失稳机理，建立寒区排土场灾变的干预机制。研究结果不仅填补了冻融循环作用下岩质散体力学特性和诱发寒区排土场灾变机理的研究空白，也为寒区资源的开发、排土场的稳定性分析提供理论基础。

排土场边坡是由矿山开采活动中剥离的不同粒径岩块和表层土堆积而成的巨型人工土石混合体的松散堆积体。在低温环境中，反复循环的冻结-消融作用会对排土场边坡表层的岩块与岩块间、岩块与土间的黏结强度、以及不同粒径岩块的力学特性均会受到弱化，进而诱发边坡失稳。因此，解决冻融循环作用下排土场土石混合体物理力学特性演化将是开展寒冷地区排土场散体边坡安全稳定的关键。本次课题研究以黑龙江某石墨矿排土场边坡为研究对象，围绕冻融循环条件下排土场边坡安全稳定开展岩质散体粒径分布规律、反复冻胀-消融作用下石多尺度损伤机理、多场耦合作用下岩石冻胀力演化模型及损伤本构模型、多场耦合作用下岩石类材料近场动力学模型、冻融循环作用下岩质散体力学特性及劣化机理试验研究。分析了坡面不同高度散体颗粒的粒径的分布规律，建立了排土场粒径分布规律的表达式。揭示了循环冻融次数和岩体中裂隙的倾角对应力-应变曲线、弹性模量、峰值应力、峰值应变、拉伸强度、断裂韧度等力学参数的影响规律。推导了THMC多场耦合作用下岩石类材料冻胀力计算公式，建立了岩石多场耦合作用下的本构模型。利用近场动力学最小二乘法建立了考虑热对流效应的热传导方程的近场动力学形式，建立了岩石类材料渗流场-温度场-应力场耦合作用的近场动力学模型。最后，探讨了循环冻融作用下岩质散体微观孔隙结构的演变规律及宏观力学特性劣化机理。研究成果可为低温寒冷地区露天边坡、排土场边坡、路肩边坡等边坡工程的安全防护提供理论指导与技术支撑。