基于稳健模拟退火-单纯形混合算法的微震定位研究

Study of microseismic positioning based on steady simulated annealing-simplex hybrid algorithm

为提高矿井微震的定位精度,通过模拟试验对比分析常规定位及新方法在定位求解中的适用范围及优缺点,研究反演未知变量数目、检波器的密度、波速等对各自定位方法的影响。基于单纯形法的优点,并结合模拟退火法的全局收敛性,提出采用稳健的模拟退火-单纯形法进行微震定位。研究发现,该方法不必直接搜索发震时刻,只需通过稳健方法预先估算,利用较少的检波器就可进行微震定位,且基本不受初始波速影响,从而大大减少搜索步数,有效地提高定位精度及收敛速度。以柿竹园矿人工爆破定位测试试验为例,重点分析比较模拟退火-单纯形法、稳健模拟退火-单纯形法及其他定位方法的空间绝对距离及目标函数误差,认为检波器数量较多且可获得理想的P波信息时,应用非线性最小二乘法能求出可信的结果;其余定位方法的三维定位误差及目标函数误差相差不大,但稳健模拟退火-单纯形法目标函数误差最小,稳定性最高,可在矿井微震定位中推广使用。

To improve the accuracy of microseismic source location, the application scope, the advantages and disadvantages of traditional and improvement algorithms in locating solving were comparatively analyzed based on the simulation experiment. The influence of unknown variables, sensors＇ density and P wave velocity on the location algorithms were studied respectively. Based on the advantages of the simplex and the global convergence characteristics of the simulated annealing, it was proposed that taking the steady simulated annealing-simplex algorithm located the microseism. The study shows that this algorithm is a simple estimation in advance by steady arithmetic without directly searching for the seismogenic moment. The searching steps can be greatly reduced and the location accuracy and convergence velocity can be improved. So the microseismic focus can be effectively located with less sensors without being affected by the initial velocity. Taking the artificial blasting location test experiment of a mine as an example, the errors of both the location accuracy and objective function for the simulated annealing-simplex, the steady simulated annealing-simplex and the other algorithms were specially analyzed. It is widely believed that applying the nonlinear least square algorithm can get reliable results when there are more sensors and better information of P wave. The errors of three-dimensional location and objective function of the other location algorithms are basically the same. But the objective function error of the steady simulated annealing-simplex algorithm is the minimum; and the stability is the best. So this algorithm with higher reliability and stability has obvious advantages; and it can be widely used for the microseismic location in mines.