基于数值模拟的房柱式采空区关键层-岩柱系统破坏机理分析

Failure mechanism of the key strata-pillar system in room and pillar goaf based ona numerieal simulation

为了提高浅埋房柱式采空区稳定性评价的精度和可靠性,本文以吕梁某高速公路桥梁下伏采空区为研究区,建立采空区二维模型,运用有限元数值模拟的方法,研究关键层厚度对关键层-岩柱系统应力场的影响。研究发现关键层-岩柱系统发生了应力重分布,应力集中主要位于岩柱的帮角、关键层跨中表面及岩柱正上方关键层上表面。随关键层厚度减小,岩柱应力呈先增后减趋势,关键层应力先缓慢增大后急剧增大。建立关键层-岩柱系统稳定性与关键层厚度之间的定量关系,确定关键层局部破裂、岩柱失稳、岩柱保持长期稳定时的关键层临界厚度分别为3.2 m、5.8 m和6.7 m。将数值模拟成果应用到实际工程中,发现与实际资料的吻合度较高。

In order to improve the precision and reliability of stability evaluation in shallow buried room and pillar goaf, a 2D geological model which based on geological data of the goaf under expressway with bridges in Lvlang was established and was applied to study the effect of key strata thickness on in situ stress of the key strata-pillar system by using finite element. The results show that the key strata-pillar system causes the in situ stress to be distributed, the stress in angle of pillars , mid-span and the surface of the strata-pillar directly above pillars are highly concentrated, With the thickness of key strata decreases, pillar stress firstly increases and then decreases, and the key strata increases slowly at first and then sharply. Quantitative relations between key strata thickness and the key strata-pillar system are established. The critical key strata thickness of local failure in key strata,the instability and stability with a long-term of pillar are determined to be 3.2 m, 5. 8 m and 6.7 m. The conclusions above are applied to the practical project and the results are highly consistent with actual data,