Gassy soils are distributed in relatively shallow layers the Quaternary deposit in Hangzhou Bay area. The shallow gassy soils significantly affect the construction of underground projects. Proper characterization of spatial distribution of shallow gassy soils is indispensable prior to construction of underground projects in the area. Due to the costly conditions required in the site investigation for gassy soils, only a limited number of gas pressure data can be obtained in engineering practice, which leads to the uncertainty in characterizing spatial distribution of gassy soils. Determining the number of boreholes for investigating gassy soils and their corresponding locations is pivotal to reducing construction risk induced by gassy soils. However, this primarily relies on the engineering experience in the current site investigation practice. This study develops a probabilistic site investigation optimization method for planning investigation schemes (including the number and locations of boreholes) of gassy soils based on the conditional random field and Monte Carlo simulation. The proposed method aims to provide an optimal investigation scheme before the site investigation based on prior knowledge. Finally, the proposed approach is illustrated using a case study.
References
[1]
Li, Y. and Lin, C. (2010) Exploration Methods for Late Quaternary Shallow Biogenic Gas Reservoirs in the Hangzhou Bay Area, Eastern China. AAPGBulletin, 94, 1741-1759. https://doi.org/10.1306/06301009184
[2]
Lin, C.M., Gu, L.X., Li, G.Y., Zhao, Y.Y. and Jiang, W.S. (2004) Geology and Formation Mechanism of Late Quaternary Shallow Biogenic Gas Reservoirs in the Hangzhou Bay Area, Eastern China. AAPGBulletin, 88, 613-625. https://doi.org/10.1306/01070403038
[3]
Li, L., Zhao, Y. and Yu, L. (2009) Exploration for Quaternary Shallow Biogenic Gas by Sealed Core Drilling and Modified CPT. Coal Geology and Exploration, 37, 72-76. (In Chinese)
[4]
Jiang, W., Ye, Z., Zheng, H. and Yong, Z. (1997) Quaternary Shallow Gas Characteristics in Hangzhou Bay and Exploration Method. Natural Gas Industry, 17, 20-23. (In Chinese)
[5]
Yan, J., Sun, G., Ru, G. and Rui, S. (1998) Reservoir Formation Conditions and Exploration Prospects of the Shallow Gas in Quaternary along the Coastal Plain of Zhejiang Province. Natural Gas Industry, 18, 16-19. (In Chinese)
[6]
Griffiths, D.V. and Fenton, G.A. (2007) Probabilistic Methods in Geotechnical Engineering. Springer.
[7]
Liu, L., Cheng, Y. and Zhang, S. (2017) Conditional Random Field Reliability Analysis of a Cohesion-Frictional Slope. ComputersandGeotechnics, 82, 173-186. https://doi.org/10.1016/j.compgeo.2016.10.014
[8]
Henderson, C.R. (1975) Best Linear Unbiased Estimation and Prediction under a Selection Model. Biometrics, 31, 423-447. https://doi.org/10.2307/2529430
[9]
Huang, S.P., Quek, S.T. and Phoon, K.K. (2001) Convergence Study of the Truncated Karhunen-Loeve Expansion for Simulation of Stochastic Processes. InternationalJournalforNumericalMethodsinEngineering, 52, 1029-1043. https://doi.org/10.1002/nme.255
[10]
Phoon, K.K., Huang, S.P. and Quek, S.T. (2002) Implementation of Karhunen-Loeve Expansion for Simulation Using a Wavelet-Galerkin Scheme. ProbabilisticEngineeringMechanics, 17, 293-303. https://doi.org/10.1016/s0266-8920(02)00013-9
[11]
Vick, S.G. (2002) Degrees of Belief: Subjective Probability and Engineering Judgment. ASCE Press.
