基于TRT系统的地质构造三维成像技术及其改进方法

The three-dimensional imaging technology and its improvement for geological structure based on the TRT system

TRT技术是利用地震波反射原理来实现对灾害体的辨识,利用震源点与接收点共同组成的随时间变化的共焦椭球体来实现对灾害体的定位.根据TRT成果图像异常区域与隧道实际灾害的对应情况,将TRT图像异常区域划分为集群异常区、单体异常区、错断异常区、互层异常区四种类型.针对TRT技术自身存在的直达波速计算不准确、背景波速取定不合理等问题,提出了相应的改进方法,一方面通过计算出直达波在隧道洞身的实际传播的最小轨迹,求得震源点到接收点的实际直达波速;另一方面根据实际直达波速的分布特征,求出正态分布条件下,实际直达波速在置信水平为1-a的置信区间,并将置信区间的上下限值作为背景波速录入TRT系统,得出两组TRT成果图像,这样就改变了人工取定背景波速所存在的单一性与盲目性,使得改进后的灾害预测有了一定的区间考量.通过实例验证,发现改进后的预测效果明显优于改进前采用人工取定背景波速时的预测效果,并在一定程度上避免了灾害漏报的可能.

The TRT technology is used to achieve recognition of the disaster body with the help of seismic wave reflection principle. It can locate the disaster body using a confocal ellipsoid changing with time composed by seismic focus and the receiving focus. According to the comparing the abnormal image area formed by TRT technology with the tunnel disaster area caused by the earthquake, the TRT anomaly area is divided into four types, which are cluster abnormal area, single abnormal area, faulted abnormal area and interbedded abnormal area. Aiming at TRT technologyrs own problems that the calculation of direct wave velocity is not enough accurate and the setting of background wave velocity is unreasonable, a corresponding improvement method is proposed. On one hand, to get the actual direct wave velocity between seismic focus and the receiving focus, through calculating the minimum actually spreading track of the direct waves in the tunnel is obtained. On the other hand, 1-a confidence interval of actual direct wave velocity in the condition of Gaussian distribution is calculated, based on the distribution of direct wave velocity. To entry the upper and lower limits of the confidence interval as the background velocity into the TRT system, two sets TRT＇s images, are obtained which gets rid of the singleness and aimless on setting the background wave velocity, and makes a certain confidence interval consideration for the improved geological hazard forecasting. The result of the living example shows that the effect of improved geological hazard forecasting is much better than the forecasting effect of setting the background wave velocity to a certain degree, that avoids the possibility of the omission in disaster prediction.