were divided into several parts by tunnel shafts along the tunnel alignment.
Independent construction procedures were progressed for
each part. DK25+067, DK25+092 and DK26+940 were located at
a part where the southbound tunnel was the preceding tunnel, whereas
DK25+142 was located, like DK26+970, at a part where the
northbound tunnel was the preceding tunnel.
It can be concluded that although there is a significant enlargement
of ground settlement when the tunnel is passing beneath (i.e. B and E–
A), both the pre-settlement (i.e. A) and the post-settlement (i.e. D–B)
still exist, deserving due attention. This finding can be regarded as
the main difference between Suwansawat and Einstein' work [14]
and this study. Their simplified method implied that they omitted
the pre-settlement of the following tunnel, i.e. A, and used B directly
to represent C. Moreover, they considered that the overall additional
settlement was only induced by the following tunnel. As a result, the
settlement of the preceding tunnel, i.e. (D–B), was also omitted. This