工作面回采速度对地表下沉的影响

为分析工作面回采速度对地表下沉的影响,基于概率积分法静态下沉预计模型,引入时间参数,建立了概率积分法动态预计模型。采用数学模型分析回采速度与地表下沉、下沉速度、下沉加速度的关系,并通过Matlab直观表达。工作面回采速度对同一时间地表点下沉量、下沉启动时间、下沉时间、达到最大下沉时间、下沉速度、最大下沉速度、下沉加速度、下沉加速度峰值及达到峰值时间均有较大影响。回采速度与地表形变呈非线性关系,当回采速度达到一定阈值后,其与地表形变相关性越差。

关于地表点下沉时间函数的研究——改进的克诺特时间函数

克诺特时间函数被认为可以描述地表点下沉的全过程。通过理论推导并与实测资料对比,证明了可采用传统的地表下沉时间函数——克诺特时间函数来描述地表点下沉全过程存在的缺陷;经过对地表点下沉规律的分析,提出更为合理的地表点下沉时间函数——改进的克诺特时间函数,用实测资料进行了检验,证明改进后的克诺特时间函数与实际情况吻合良好。

Study on the Rainfall and Aftershock Threshold for Debris Flow of Post-earthquake

Due to the special condition of provenance and disaster environment after "5·12" Earthquake, the probability and conditions of the occurrence of gully debris flow change greatly after the event, which make it difficult to prevent disaster effectively. In this study the hydrological model of ground water table in loose sediment is established. According to infinite slope theory, the safety factor of deposits is defined as the ratio of resistance force to driving force. The starting condition of post-earthquake gully debris flow is clearly studied by analyzing the effects of rainfall intensity, seismic strength, slope gradient and mechanical properties on the balance of accumulation body. Then the formulas of rainfall and aftershock threshold for starting of gully debris flow are proposed, and an example is given to illustrate the effect of rainfall, aftershocks and their coupling action on a debris flow. The result shows the critical rainfall intensity decreases as the lateral seismic acceleration and channel gradient increases, while the critical intensity linearly increases as the friction angle increases.

改进的Konthe地表沉陷时间函数模型

基于地下采矿引起的地表沉陷随时间变化的规律,分析了描述地表沉陷动态过程的knothe时间函数的不足,用数学分析的方法改进了knothe时间函数,改进后的时间函数模型可较准确地描述地表沉陷的动态过程,该模型求得的下沉速度的变化为0→vmax→0,下沉加速度的变化为0→+am ax→0→-am ax→0,并且该模型能求出沉陷速度最大的时间,所举矿山实测实例证明该模型可较正确地描述地表下沉的动态过程。