Numerical simulation of resistivity testing on soft clay samples with reference to permeability prediction | |
| Author | Kanidtha Prarom |
| Call Number | AIT Thesis no.GE-16-12 |
| Subject(s) | Predictive control. Engineering geotechnical. |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Geotechnical and Earth Resources Engineering with area of specialization in Geosystem Exploration and Petroleum Geoengineering, School of Engineering and Technology |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. GE-16-12 |
| Abstract | Resistivity measurement on core sam ples in the laboratory often ignore the effect of core ends and electric flow in a small medium . Therefore, they need to be corrected for the finite shape and size of the specimen . The aim of this study is to perform numerical simulation of electrical flow by using COMSOL multiphysics on different resistivity setups on the soft clay core samples to help finding out the correction factor to correct resistivity measurements. The empirical and numerical correction factor were calculated in this study. The emp irical correction factors were obtained by measuring resistivity on two different setups of soil samples, one by the 4 - electrode Wenner array and another one by a setup proposed by Giao et al. ( 2003 ). Furthermore, a total of more than 200 FEM simulation we re conducted for different core length and diameter. The empirical and numerical correction factor were compared, and were used to correct the resistivity measurement . These corrected resistivity and measured chargeability were used to predict the permeabi lity. As a result, the measured resistivity of Bangkok soft clay range from 4.64 to 10.90 m. The corrected resistivity ranges from 3.51 to 7.78 m . Therefore, the empirical correction factor was found to be from 1.23 to 2.81. The numerical correction factor, which was found based on FEM simulation by COMSOL multiphysic, with the ratio of length over electrode spacing ranging from 3.00 to 12.00, and the ratio of diameter over electrode spacing from 1 . 70 to 6 . 00 . The correction factors based on FEM simul ation was found to be in the range from 1 . 54 to 3.03, and the corrected resistivity are in range from 2.67 to 6.61 m . The permeability predicted using sand and soil - cement mixed model were found in range from 7.32 x 10 - 16 to 2.61 x 10 - 11, and 7.85 x 10 - 18 to 1.00 x 10 - 18 m 2 , respectively. In conclusions, COMSOL multiphysic could be successfully used for simulation of electrical flow in a resistivity testing on core sample . Moreover, the results of FEM simulation match quite well with empirical values . Correction chart was successfully constructed for the range of d / a from 1.75 to 6.00, and L / a from 3.00 to 12 . 00 |
| Year | 2017 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. GE-16-12 |
| Type | Thesis |
| School | School of Engineering and Technology (SET) |
| Department | Department of Civil and Infrastucture Engineering (DCIE) |
| Academic Program/FoS | Geotechnical Engineering (GE) |
| Chairperson(s) | Pham Huy Giao; |
| Examination Committee(s) | Noppadol Phien-wej;Pinan Dawkrajai; |
| Scholarship Donor(s) | Royal Thai Government Fellowship; |
| Degree | Thesis (M. Sc.) - Asian Institute of Technology, 2017 |