Combined prospecting method of engineering VSP and seismic CT and its application on geotechnology

The Vertical Seismic Profile(VSP) and Computerized Tomography(CT) not only can be described by unified mathematical method(such as ray theory) but also can be fused in exploration work so as to become a combined technique of high resolution engineering geophysical exploration technique. Especially in the data acquisition work of cross-borehole tomography, if we sufficiently use the compatibility of VSP and CT acquisition method and design layout scientifically, we not only can get the data of cross-borehole tomography and converse VSP in the project well but also don't increase exploration cost. Such as hole array and multi-point shooting, every receiving point on the surface compose the multi-offset converse VSP gather and variable offset converse VSP gather of every source point about borehole. This whole set of high resolution technique is also easily accomplish in bigger cave engineering detection on near surface. We will introduce the combined geometry of engineering VSP and CT in part I, and introduce the designing method of seismic initial model and designing image processing flow in part II, in part III, we will give an example of combined seismic CT and VSP using in the engineering geophysics on the three gorge dam, finally we give some relevant conclusion and propose.