微动勘探中噪声场分布的不均匀性对圆形和直线形台阵的影响研究

Study on the influence of the inhomogeneity of noise field distribution on circular and linear array in microtremor exploration

为了研究微动勘探中噪声场分布的不均匀性对常用的圆形和直线形台阵提取频散曲线结果的影响,本文通过模拟噪声数据,定量分析了噪声源集中在某一方向或各向均匀分布时,利用直线形和圆形台阵得到实测频散曲线和理论频散曲线的误差.结果表明,圆形台阵的适用性较强,噪声场分布的不均匀性对提取得到的频散曲线影响较小,而直线形台阵的适用性取决于场地条件,当噪声源满足各向均匀分布时,直线形台阵可提取得到可靠的频散曲线,但当场地条件难以满足噪声源各向均匀分布时,提取得到的频散曲线误差较大.因此,即使直线形台阵施工方便,也要慎重使用.

In order to study the influence of the inhomogeneity of the noise field distribution on the results of the dispersion curve extracting from the commonly used circular and linear array in microtremor exploration,this paper quantitatively analyzes the errors of measured and theoretical dispersion curves obtained by linear and circular arrays when the noise sources are concentrated in a certain direction or uniformly distributed by simulating noise data.The results show that the applicability of circular array is flexible enough and the non-uniformity of noise field distribution has little influence on the extracted dispersion curve,while the applicability of linear array depends on the site conditions.When the wave field is isotropic,the linear array can obtain reliable dispersion curve,but when the isotropic condition cannot be satisfied,the error of extracting dispersion curve is great.Therefore,even if the linear array is convenient for field construction,it should be used carefully.