井孔△H指标及其观测系统原理
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摘要
根据地震前兆的"应力-应变原理",以及"岩石变形破坏的实质是其孔隙度发生变化"的结论,进一步应用地下水动力学中的达西定律推导得出,饱和含水层井孔在恒定流量下的动水位与该井孔静水位之差或二种不同恒定流量下的动水位之差ΔH,可以相对量度饱和含水层岩体孔隙度的变化,进而得出相对量度岩体受力变形的动态变化过程,这可作为一项新的地震前兆指标。据此设计了一种以"井孔ΔH指标"为观测对象的新型地震前兆观测系统。理论分析得出,ΔH指标仅对地下深部岩体应力-应变的变化信息敏感,对非应力-应变因素和地表干扰不敏感。已有实验初步验证了其具有抗干扰、高灵敏度和高信噪比等特性。距离实验点400km的2002年3月31日台湾花莲海外7.5级地震为ΔH指标的可行性实验提供了一个例证。
Based on the theory of seismic precursor "stressstrain" relation and the fact when deformation and destroying of the terrain under force is the changing of its porosity, ΔH, which is the difference between well dynamic level and static level under the constant flow or the difference of dynamic level under two kinds of different constant flow, can relatively measure the changing of saturated aquifer terrain porosity when using the Darcy′s law of hydrology. Furthermore ΔH can be used to relatively measure dynamic changing process of terrain deformation under force, thus it can be used to be a kind of new type of seismic precursory indexes. Based on the abovementioned facts, a kind of new seismic precursory observation system, in which the index is ΔH, is designed. Based on theoretical analysis, the index ΔH is just sensitive to changing information of stressstrain in deepseated terrain while it is not sensitive to the factor which is not caused by stressstrain changing and the interfere of ground. It has been primarily verified by some experiments that ΔH has the feature of antiinterference, high sensitivity and high signal to noise ratio. The MS 7.5 offshore earthquake, Hualian, Taiwan on May 31, 2002, which is 400km far from our experimental point, provides a case for the feasibility of index ΔH.
Based on the theory of seismic precursor "stressstrain" relation and the fact when deformation and destroying of the terrain under force is the changing of its porosity, ΔH, which is the difference between well dynamic level and static level under the constant flow or the difference of dynamic level under two kinds of different constant flow, can relatively measure the changing of saturated aquifer terrain porosity when using the Darcy′s law of hydrology. Furthermore ΔH can be used to relatively measure dynamic changing process of terrain deformation under force, thus it can be used to be a kind of new type of seismic precursory indexes. Based on the abovementioned facts, a kind of new seismic precursory observation system, in which the index is ΔH, is designed. Based on theoretical analysis, the index ΔH is just sensitive to changing information of stressstrain in deepseated terrain while it is not sensitive to the factor which is not caused by stressstrain changing and the interfere of ground. It has been primarily verified by some experiments that ΔH has the feature of antiinterference, high sensitivity and high signal to noise ratio. The MS 7.5 offshore earthquake, Hualian, Taiwan on May 31, 2002, which is 400km far from our experimental point, provides a case for the feasibility of index ΔH.
引文
[1] 汪成民,车用太,万迪坤,等.地下水微动态研究.北京:地震出版社,1988.126-128.
[2] 弗里泽RA,彻里JA.地下水[M].吴静方译.北京:地震出版社,1987.10-11,228-231.
[3] 耿乃光,李纪汉,郝晋升,等.脆性岩石破裂的前兆变形和前兆应力降[J].地震,1986,6(1):9-12.
[2] 弗里泽RA,彻里JA.地下水[M].吴静方译.北京:地震出版社,1987.10-11,228-231.
[3] 耿乃光,李纪汉,郝晋升,等.脆性岩石破裂的前兆变形和前兆应力降[J].地震,1986,6(1):9-12.
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