oi
Yu
242
P with respect to the stations I, II, III etc. respectively. This con
dition is mentioned and investigated in the literature [i], [2].
(See figure 3.) It appears that the orientation bearings should be
situated at angles of less than 71/2 with the bearing 4>i.p on both
sides of this line. The lengths of these bearings should be short,
even shorter than the distance di p.
not on scale
6= Gravity point of A and
should coincide with 0
Figure 3
The third term on the right hand side of the equation (12) however
does not attain a minimum when the distances d\ i are short, on the
contrary it increases in value as both the a and b coefficients are
inversely proportional to these distances. This term is discussed
in the sections 4 and 5.
3. The method of intersection is frequently used for the measure
ment of dam deflections [3]. A typical triangulation is shown in
the figure 4.
The reference stations outside the pressure zone of the dam are
IV and V the coordinates of which are assumed free of errors. A
rigorous adjustment of the triangulation of the forward reference
stations I, II, and III is carried out. If the coordinates and the
orientations are introduced as parameters, the matrix of weight
coefficients becomes:
Xi Y1 Xu Yu Oi On On 1
Xi
Yi
On
Om
QxiXi QxiYi QxiXll QxjYu
QyiYi QyiXu QyiYu
Qxnxn QxuYu
Qyuyu
QxiOl QxiOn QxiOlll
QyiOi QyiOu QYiOiu
QxnOl QxilOll Qx\\Oil\
Qyu01 QYuOu QYhOiu
Q01O1 QoiOll QoiOlU
Qonou Qonoiu
QoiuOUl
