ABSTRACT
ABSTRACT: Trenchless technologies have been steadily growing in underground projects in urban areas. It is essential to obtain soil data at trenchless zones in order to successfully complete construction of underground projects. Consequently, a method for detecting soil conditions has been developed in this paper by the integrating Horizontal Directional Drilling (HDD) technique and cross-hole seismic tomography. Firstly, several small-diameter holes along trenchless projects are drilled by using the HDD technique, and Polyethylene (PE) pipes are installed along the designed path followed by placing detecting instrumentations in PE pipes. Travel times of each source–receiver pair are collected to reconstruct the velocity distributions between the boreholes. Finally, the soil conditions and anomalous zones are determined. To verify the feasibility of the proposed method, a main waterpipe constructed by the pipe jacking technique is taken as an example to detect obstacles distributed beneath bridges. The field results show that the proposed method is capable of detecting soil conditions for trenchless projects.
