Hydromechanical characterization of gas transport amidst uncertainty for underground nuclear explosion detection

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外文摘要：Given the challenge of definitively discriminating between chemical and nuclear explosions using seismic methods alone,surface detection of signature noble gas radioisotopes is considered a positive identification of underground nuclear explosions(UNEs).However,the migration of signature radio-nuclide gases between the nuclear cavity and surface is not well understood because complex processes are involved,including the generation of complex fracture networks,reactivation of natural fractures and faults,and thermo-hydro-mechanical-chemical(THMC)coupling of radionuclide gas transport in the subsurface.In this study,we provide an experimental investigation of hydro-mechanical(HM)coupling among gas flow,stress states,rock deformation,and rock damage using a unique multi-physics triaxial direct shear rock testing system.The testing system also features redundant gas pressure and flow rate measurements,well suited for parameter uncertainty quantification.Using porous tuff and tight granite samples that are relevant to historic UNE tests,we measured the Biot effective stress coefficient,rock matrix gas permeability,and fracture gas permeability at a range of pore pressure and stress conditions.The Biot effective stress coefficient varies from 0.69 to 1 for the tuff,whose porosity averages 35.3％±0.7％,while this coefficient varies from 0.51 to 0.78 for the tight granite(porosity＜1％,perhaps an underestimate).Matrix gas permeability is strongly correlated to effective stress for the granite,but not for the porous tuff.Our experiments reveal the following key engineering implications on transport of radionuclide gases post a UNE event:(1)The porous tuff shows apparent fracture dilation or compression upon stress changes,which does not necessarily change the gas permeability;(2)The granite fracture permeability shows strong stress sensitivity and is positively related to shear displace-ment;and(3)Hydromechanical coupling among stress states,rock damage,and gas flow appears to be stronger in tight granite than in porous tuff.

外文关键词：

Underground nuclear explosion uncertaintyquantificationRadionuclide transportBiot effective stress coefficientFracture permeabilityMatrix permeability

作者：

Wenfeng Li、Chelsea W.Neil、J William Carey、Meng Meng、Luke P.Frash、Philip H.Stauffer

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作者单位：

Earth and Environmental Sciences,Los Alamos National Laboratory,Los Alamos,NM,87544,USA

Department of Mineral Engineering,New Mexico Tech,Socorro,NM,87801,USA

基金：

Laboratory Directed Research &Development(LDRD)program at the Los Alamos National Laboratory(LANL)

项目编号：

20220019DR

出版年：

2024

DOI：

10.1016/j.jrmge.2023.09.018

岩石力学与岩土工程学报(英文版)

中国科学院武汉岩土力学所中国岩石力学与工程学会武汉大学

岩石力学与岩土工程学报(英文版)

CSTPCD

影响因子：0.404

ISSN：1674-7755

年,卷(期)：2024.16(6)