<p>Organic marine clays are prevalent in coastal regions where urban development increasingly demands reliable geotechnical design under thermally affected conditions. This study investigates the thermo-mechanical behavior of Pak Phanang organic marine clay subjected to elevated temperatures and varying stress histories. A novel hydrothermal triaxial apparatus was developed to conduct temperature-controlled undrained compression tests up to 100 °C with precise thermal regulation (± 0.1 °C). A comprehensive experimental program examined the combined effects of three temperatures (30 °C, 45 °C, and 60 °C) and four over-consolidation ratios (OCR = 1, 2, 4, and 8) on stress–strain relationships, excess pore water pressure (<InlineEquation ID="IEq1"> <EquationSource Format="TEX">$\Delta u$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi mathvariant="normal">Δ</mi> <mi>u</mi> </mrow> </math></EquationSource> </InlineEquation>) development, and effective stress paths. Physical characterization including X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA–DSC) revealed that heating progressively reduced liquid limit (<InlineEquation ID="IEq2"> <EquationSource Format="TEX">${w}_{L}$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>w</mi> <mi>L</mi> </msub> </math></EquationSource> </InlineEquation>) from 109 to 70.5% due to free/bound water loss, with two distinct thermal response stages at 30–200 °C and 430–600 °C. The results demonstrate that elevated temperatures significantly enhance undrained shear strength and secant modulus (<InlineEquation ID="IEq3"> <EquationSource Format="TEX">${E}_{50}$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>E</mi> <mn>50</mn> </msub> </math></EquationSource> </InlineEquation>), with peak deviator stress (<InlineEquation ID="IEq4"> <EquationSource Format="TEX">${q}_{f}$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>q</mi> <mi>f</mi> </msub> </math></EquationSource> </InlineEquation>) increasing by 20–34% when heated from 30 to 60 °C. This strengthening effect is more pronounced in normally consolidated specimens (OCR = 1) than in over-consolidated states. Empirical linear relationships were developed to quantify temperature effects on <InlineEquation ID="IEq5"> <EquationSource Format="TEX">${q}_{f}$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>q</mi> <mi>f</mi> </msub> </math></EquationSource> </InlineEquation>, <InlineEquation ID="IEq6"> <EquationSource Format="TEX">${E}_{50}$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>E</mi> <mn>50</mn> </msub> </math></EquationSource> </InlineEquation>, and <InlineEquation ID="IEq7"> <EquationSource Format="TEX">$\Delta u$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi mathvariant="normal">Δ</mi> <mi>u</mi> </mrow> </math></EquationSource> </InlineEquation> at failure (<InlineEquation ID="IEq8"> <EquationSource Format="TEX">$\Delta {u}_{f}$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi mathvariant="normal">Δ</mi> <msub> <mi>u</mi> <mi>f</mi> </msub> </mrow> </math></EquationSource> </InlineEquation>). The findings indicate that thermal loading enhances the mechanical response of the soil through thermo-mechanical and thermo-hydraulic processes associated with drained heating and thermal consolidation. Based on these observations, the potential engineering implications of integrating moderate heat transfer (45–60 °C) with vacuum consolidation are discussed conceptually as a direction for future ground-improvement applications.</p>

Thermo-Mechanical Behavior of Organic Marine Clay Under Controlled Heating and Stress History: Implications for Vacuum-Thermal Ground Improvement

期刊论文
发表日期：

2026年8月5日

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Thanakorn Chompoorat,
Watchara Srisakul,
Tanan Chub-Uppakarn,
Pitthaya Jamsawang,
Pornkasem Jongpradist

摘要

Organic marine clays are prevalent in coastal regions where urban development increasingly demands reliable geotechnical design under thermally affected conditions. This study investigates the thermo-mechanical behavior of Pak Phanang organic marine clay subjected to elevated temperatures and varying stress histories. A novel hydrothermal triaxial apparatus was developed to conduct temperature-controlled undrained compression tests up to 100 °C with precise thermal regulation (± 0.1 °C). A comprehensive experimental program examined the combined effects of three temperatures (30 °C, 45 °C, and 60 °C) and four over-consolidation ratios (OCR = 1, 2, 4, and 8) on stress–strain relationships, excess pore water pressure ( $\Delta u$ $Δ u$ ) development, and effective stress paths. Physical characterization including X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA–DSC) revealed that heating progressively reduced liquid limit ( ${w}_{L}$ $w_{L}$ ) from 109 to 70.5% due to free/bound water loss, with two distinct thermal response stages at 30–200 °C and 430–600 °C. The results demonstrate that elevated temperatures significantly enhance undrained shear strength and secant modulus ( ${E}_{50}$ $E_{50}$ ), with peak deviator stress ( ${q}_{f}$ $q_{f}$ ) increasing by 20–34% when heated from 30 to 60 °C. This strengthening effect is more pronounced in normally consolidated specimens (OCR = 1) than in over-consolidated states. Empirical linear relationships were developed to quantify temperature effects on ${q}_{f}$ $q_{f}$ , ${E}_{50}$ $E_{50}$ , and $\Delta u$ $Δ u$ at failure ( $\Delta {u}_{f}$ $Δ u_{f}$ ). The findings indicate that thermal loading enhances the mechanical response of the soil through thermo-mechanical and thermo-hydraulic processes associated with drained heating and thermal consolidation. Based on these observations, the potential engineering implications of integrating moderate heat transfer (45–60 °C) with vacuum consolidation are discussed conceptually as a direction for future ground-improvement applications.