有盖中弱风化岩体的弹性波有效激励与信号检测

浅层地震勘探在工程领域广泛应用,但在岩溶地域,由于覆盖层与中—弱风化岩石层之间存在明显的波阻抗分解面,入射波的大部分能量被约束在覆盖层中,从而难以在基岩中形成有效激励的弹性波,以至难以准确探测基岩体内的溶洞、断层等异常的响应。以两层简化模型模拟该类地层结构,通过波动方程的解析计算,发现基岩表面的能量透射规律,从理论上说明在浅层乃至超浅层地震勘探中,选择小偏移距和临界角附近横波SV测量的可能性,通过各种因素的综合考虑,力争获得目的体的最大响应信号。

EFFECTIVE ELASTIC WAVE STIMULATION AND SIGNAL DETECTION OF MEDIUM-TO-WEAK COVERED WEATHERED ROCK

Since there exists a distinct wave impedance surface between the cover and the medium-to-weak weathered rock, most energy of the incident wave was restrained in the cover and it is very difficult to stimulate effective elastic wave in the rock. Therefore, the response signal of the cavern or fault in the rock was too weak to record. Simplifying this kind of structure by two layer model together with the analysis and calculation of the wave equation, we can find the penetration laws of the incident energy on rock surface and then theoretically show that it is possible to choose little offset and near critical angle SVwave measuring in shallow or ultra shallow seismic survey. The consideration of as many factors as possible can lead to good ideas with which we can stimulate the most distinct response signal of the concealed targets.