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本文认真分析了地震破裂期间热迁移和流体流动对断层面热、水文学和力学响应的影响。采用数学模拟方法解释热、流体压力和应力场的耦合。结果表明,在地震期间,破裂面受热而达到孔隙流体热膨胀所需要的温度,热膨胀可抵消因流体流动产生的流体损失率和因孔隙膨胀产生的流体容积变化。这种条件一旦确立,孔隙流体增压和剪切强度迅速降低到足以将孔隙流体的热增压维持在岩石静压力值附近。如果初始流体压力是静水压力,那么破裂面上达到的最终温度将随深度而增加,这是因为达到接近岩石静压力值以前能够发生比较大的温度上升。热增压的速率主要取决于周围多孔介质的水力学特点、断层面的摩擦系数和滑动速度。如果渗透率超过10(-15)米~2,或多孔介质的压缩率超过10(-8)/帕,那么热增压起重大作用以前断层面上可能会发生摩擦熔融。如果摩擦系数低于10(-1);并且滑动速度低于10(-2)米/秒,那么在地震期间断层面上的热增压或摩擦熔融是否能引起断层动力剪切强度的降低尚不能确定。
This paper carefully analyzes the effects of heat transfer and fluid flow on the thermal, hydrological and mechanical responses of fault planes during earthquake rupture. The mathematical simulation method is used to explain the coupling of heat, fluid pressure and stress field. The results show that during the earthquake, the rupture surface is heated to reach the temperature needed for the thermal expansion of the pore fluid. The thermal expansion can offset the fluid loss due to the fluid flow and the change of the fluid volume due to the pore expansion. Once this condition is established, the pore fluid pressurization and shear strength are rapidly reduced enough to maintain the thermal pressurization of the pore fluid near the value of the rock static pressure. If the initial fluid pressure is hydrostatic pressure, the final temperature reached on the rupture surface will increase with depth due to the relatively large temperature rise that can occur before the hydrostatic pressure is approached. The rate of hot pressurization mainly depends on the hydraulic characteristics of the surrounding porous media, the friction coefficient of the fault plane and the sliding velocity. If the permeability exceeds 10 (-15) m -2, or the compressibility of the porous medium exceeds 10 (-8) / Pa, friction melting may occur on the fault plane before thermal pressurization lifting plays a major role. If the friction coefficient is lower than 10 (-1) and the sliding speed is lower than 10 (-2) m / s, can the thermal or frictional melting on the fault plane during the earthquake lead to the decrease of the dynamic shear strength? Can not be sure.