基于重球触地实验的空区塌落振动分析及治理

根据相似理论,以重球落地实验模拟采空区坍塌进而指导采空区治理为出发点,在振动波动特性分析的基础上,分别开展了质量为4 kg和10 kg的重球从1.0、1.5和2.0 m的高度落地的峰值振动速度测试实验;首次提出了累计振动速度衰减率和相对能量比概念;以普氏拱理论为基础,分析了采空区坍塌振动速度。研究表明:振动速度与重球质量和落地高度成正相关,且前者对累计衰减率的影响大于后者;随着测点距离的增大,振动速度整体表现为衰减趋势;重球质量为4 kg和10 kg时,在水平距离重球落地点3.0 m处的累计衰减率分别为79.79%~81.61%和79.95%~83.52%。不同介质交界面的反射和折射可引起振动速度的小幅度“跃增”。重球质量对振动能量衰减影响明显;质量越大,近区能量衰减越慢。采空区冒落体582.5~5 926.5 t,引起的振动速度远大于边坡安全允许值。采用“采空区顶板崩落+边坡削坡”方案进行治理后,边坡安全系数可达到1.26,消除采空区安全隐患。

Goaf collapse vibration analysis and disposal based on a experiment of heavy ball touchdown

Based on the similarity theory,the heavy ball landing experiments were conducted to simulate the collapse of the goaf in order to provide guidance for the goaf disposal.The particle peak vibration velocities corresponding to the balls with the mass 4 kg and 10 kg dropping from 1.0,1.5 and 2.0 m respectively were measured experimentally on the basis of characteristics analysis of vibration wave.For the first time,the concepts of cumulative attenuation rate of vibration velocity and relative energy ratio were proposed.The collapse vibration velocity of the goaf was analyzed with the help of the Protodyakonov’s arch theory.The study shows that the mass and dropping height of the heavy ball are positively related to the vibration velocity,and the former has greater influence on the cumulative attenuation rate than that of the latter.With the increase of measuring distance,the overall vibration velocity shows an attenuation trend.The accumulative decay rates for 4 kg and 10 kg heavy balls at 3.0 m are 79.79%81.61%and 79.95%83.52%,respectively.Reflections and refractions at the interface of different media can cause a small“jump increase”in vibration velocity.The mass has a significant effect on vibration energy attenuation:the greater the mass,the slower the energy attenuation in the near area.The goaf collapsed mass is 582.5 t to 5 926.5 t and it causes the particle vibration velocity to be much larger than that of the safety allowable value.With the comprehensive treatment plan of“roof caving+slope slope cutting”,the slope safety factor can reach 1.26,completely eliminating the hidden dangers in the goaf area.