基于地震活动性参数b值的地应力评估方法研究

在铁路选线的可行性研究阶段,当线路方案尚未确定时,不宜通过大规模的钻探查明地应力数值,而希望借鉴现有资料或经验公式对地应力状况有所把握。国内外已有研究表明,在反映地震震级与发生频率的幂律关系中,幂指数b值与地应力水平具有反相关关系,据此提出增加参数b,对水平主应力随埋深分布规律统计回归方程进行修正的方法。以川藏交通廊道地应力分析为例,绘制地震活动性参数b值的空间分布云图;基于研究区已有地应力实测数据,以埋深H和b值作为自变量,拟合得到地应力量值的评估模型,经检验,与目前仅采用埋深作为自变量的方法相比,评估精度明显提高。

Crustal Stress Evaluation Method Based on Seismic Activity Parameter b-value

During the feasibility study of railway route selection,it is inadvisable to conduct large-scale on-site drilling to investigate crustal stress while the route is not determined and it is helpful to rely on existing data or empirical formula to understand the crustal stress situation. Researches have shown the inverse relationship between power exponent b-value and crustal stress. Thus,a correction method of adding b-value to the maximum horizontal principal stress varying with the depth formula is proposed. In view of the earth stress analysis in Sichuan- Tibet moraine transportation corridor,the seismic activity parameter b-value's spatial distribution nephogram is drawn out. Based on the existing measured stress data,and b-value and depth H-value as independent variables,an evaluation model of crustal stress is developed. Compared with the current method which uses the depth as the only independent variable,the evaluation precision of the model is much higher.