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386
Andesite
Iron ore
27.4 kPa
31.0 kPa
39.2°
46.2°
187.0 kPa
318.0kPa
0.08
0.08
By the use of the proposed AACS, the five slopes in above open-pit mine are analyzed by assuming m
=100, a=1.0, /J =1.0, p =0.6, p Q =Q.%, ^=200 and the computation results are shown in Table 2.
TABLE2
THE COMPUTATION RESULTS OF EXAMPLE 2
Slope number
N7
Nil
N15
N19
N23
Height of
slope, H
120.0m
118.0m
115.0m
117.0m
116.0m
Dip angle of
slope, a
44.0°
44.0°
44.0°
44.0°
44.0°
Safety factor with
no earthquake, F s
1.4910
1,5098
1.5405
1.5104
1.5217
Safety factor with
earthquake, F^
1.2846
1.2932
1.3143
1.2979
1.3122
Relative
deviation
13.84%
14.35%
14.68%
14.07%
13.77%
Table 2 shows that the safety factors of slopes in earthquake zone decrease by 13.77 to 14.68 percent as
compared to the safety factors of slopes in no earthquake condition. The average decrease of safety factor
is 14.14%.
CONCLUSIONS
The stability analysis of complicated slope is actually a nonlinear programming problem with multiple
extreme values and the objective function usually is not explicit. The traditional optimization methods are
difficulty to find out the most dangerous slip surface. For the ant colony algorithm being fit for evaluating
the influence of earthquake on the stability of slopes in earthquake zone, the structure of basic ant colony
system (ACS) is modified. A heuristic operator is introduced to determine the transfer probability of ant
and an adaptive operator is presented to avoid the phenomenon of stagnation in evolution process and then
a new adaptive ant colony system (AACS) is proposed.
Two examples are given to verify the adaptive ant colony system. Example 1 is used to verify the accuracy
of the proposed method The computation results show that this method is feasible and reliable and it can
also be used to evaluate various slopes with complicated soil layers and complicated profiles. Example 2 is
used to assess the influence of earthquake on the stability of slopes in earthquake zone. The results show
that the average decrease of safety factor of slopes under earthquake is 14.14% in the above open-pit.
ACKNOWLEDGEMENTS
This work is partly supported by the Fund of Science and Technology from Hunan province (Grant No
X99P51059).