| dc.description.abstract | The geological model is the basis for analysis, simulation and evaluation of engineering, underground environment and geological disasters. The uncertainty within the geological model will highly influence the effectiveness of these applications. The relationship of extension length of the material (stone or soil) in vertical and horizontal direction is the critical parameter when building the geological model. If the parameter can be determined could make the model more reliable.
The extension length in the vertical direction can be obtained from the borehole data, while in the horizontal direction, due to the lack of information is hard to obtain the extension length directly. The coupled Markov chain modeling method using the transition probability to calculate the probability of the different materials occur in each position. Based on Walther’s law can describe the relationship between the extension length in vertical and horizontal direction, using the transition probability in the vertical direction to calculate the transition probability in the horizontal direction. By comparing the likelihood of the material in observed scenario can obtain the most reliable parameter value of the ratio of vertical and horizontal extension.
This research has reproduced the result of the parameter determination method and applied the method to the site in Taipei basin, which has high density of the borehole data to determine the ratio of the extension length in the horizontal direction to the vertical direction in SungShan Formation. In study area A, we used different simulated directions, “left to right, up to bottom”, “right to left, up to bottom”, “left to right, bottom to up”, “right to left, bottom to up”, and the determination results are 13, 12.5, 15.5 and 11.5, respectively. From these result we found that we got different values of parameter with different simulated directions, especially when the material boundary variety is enormous.
In study area B, we chose a pair of cross sections in direction East to West, and a cross section in North to South to determine the parameter and build the geological model. The types of soils have been reclassified by particle size distribution and soil plasticity. This research has also compared the geological models based on the reclassification with the geological model based on the unified soil classification system. We used the simulated direction in “left to right, up to bottom”, the determination results of the cross sections in direction East to West were 40 and 65, North to South was 57; In “right to left, up to bottom”, the determination results of the cross sections in direction East to West were 44 and 37, North to South was 33. From the determination results we can know that the influence from the cross sections direction is small, and the lateral extension length is much longer than vertical extension length in study area. The model which used the parameter shows that is easily to identify the sub layers in SungShan Formation. That is to say, the parameter makes geological model more reliable. | en_US |