郯庐断裂带中段区域应力状态及其断层力学意义研究

发布时间：2018-11-18 20:36

【摘要】：本文研究首先收集郯庐断裂带中段的地质构造资料,全面了解研究区的地质背景。其次,应用水压致裂法和CBDM法准确获取研究区的应力数据,并对数据进行分析。再次,梳理总结了断层强度的评价指标,包括最大主应力方向与断层面夹角α和应力积累指标μm,并根据应力数据分析了郯庐断裂带中段的断层强度特征。接着,利用郯庐断裂带中段的小震震源机制解,根据断层强度评价指标分析其深部的断层强度特征。最后,利用3DEC软件模拟郯庐断裂带中段的活动性,探讨应力状态与断层强度之间的关系。基于以上研究内容,本文取得以下新的进展和认识。(1)研究区内结构面产状受隐伏断层影响,隐伏断层断层面以上结构面倾向SN,倾角约60°,与断层面产状一致;在断层面以下的结构面倾向NE,倾角约60°,是郯庐断裂带和隐伏断层共同影响的结果。(2)利用改进优化后的水压致裂法获取多组准确有效的应力数据,结果显示最大水平主应力方向平均值为N84.1°E,三向应力值关系表现为SHShSv,断层表现为逆断性质。(3)郯庐断裂带中段最大主应力与断层面夹角为64.1°~74.1°(2α*),故断层摩擦系数比较低,断层相对于脆性地壳来说比较弱。研究区内应力积累指标μm平均值为0.48,说明该区域应力积累水平较高,且地壳处于其极限状态。(4)郯庐断裂带中段μm在0.2~0.4之间区域主要分布在研究区以南,该区域发生小地震的频率比较高,应力不易积累;μm大于0.4的区域主要分布在研究区范围内以及以北渤海海域当中,说明该区域应力积累程度高。(5)根据郯庐断裂带中段的应力状态和断层摩擦系数,通过3DEC软件模拟发现,EW向挤压应力不断增大时,郯庐断裂带中段东侧的应力值增加幅度大于西侧,可能暗示东侧发生地震的可能性大于西侧。
[Abstract]:In this paper, the geological structure data of the middle section of the Tan-Lu fault zone are collected, and the geological background of the study area is comprehensively understood. Secondly, hydraulic fracturing method and CBDM method are used to accurately obtain the stress data of the study area and analyze the data. Thirdly, the evaluation indexes of the fault strength are summarized, including the angle between the maximum principal stress direction and the fault plane 伪 and the stress accumulation index 渭 m, and the characteristics of the fault strength in the middle section of the Tanlu fault zone are analyzed based on the stress data. Then, the focal mechanism of small earthquakes in the middle section of the Tanlu fault zone is used to analyze the characteristics of the deep fault strength according to the evaluation index of the fault strength. Finally, the 3DEC software is used to simulate the activity of the middle part of the Tan-Lu fault zone, and the relationship between the stress state and the fault strength is discussed. Based on the above research, this paper has made the following new progress and understanding: (1) the occurrence of structural plane in the study area is affected by hidden faults, and the tendency of the structural plane above the hidden fault plane is about 60 掳, which is consistent with the occurrence of fault plane; The NE, inclination of the structural plane below the fault plane is about 60 掳, which is the result of the influence of the Tan-Lu fault zone and the concealed fault. (2) the improved hydraulic fracturing method is used to obtain many groups of accurate and effective stress data. The results show that the average value of the maximum horizontal principal stress direction is N84.1 掳E, and the relationship of the three direction stress values is that the SHShSv, fault is inversely faulted. (3) the angle between the maximum principal stress and the fault plane is 64.1 掳~ 74.1 掳(2 伪 *) in the middle part of the Tanlu fault zone. Therefore, the coefficient of friction of faults is relatively low, and the fault is weaker than that of brittle crust. The average value of stress accumulation index 渭 m in the study area is 0.48, which indicates that the stress accumulation level in this area is high and the crust is in its limit state. (4) the area of 渭 m in the middle segment of the Tanlu fault zone is mainly distributed in the south of the study area. The frequency of small earthquakes in this area is relatively high, and the stress is not easy to accumulate. The area with 渭 m greater than 0.4 is mainly distributed in the study area and in the Bohai Sea north of the study area, indicating that the stress accumulation in the area is high. (5) according to the stress state and the friction coefficient of the fault in the middle part of the Tanlu fault zone, It is found by 3DEC simulation that the stress in the east side of the middle section of the Tanlu fault zone is larger than that in the west side when the compressive stress in the direction of EW is increasing, which may imply that the possibility of an earthquake occurring in the east side is greater than that in the west side.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P315.2

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