<p>Ground deformation induced by stress transfer from civil engineering structures often leads to settlement issues, impacting the performance of structures like roads, parking slabs, and factory floors. Polyurethane (PU) foam, known for its significant volumetric expansion, emerges as a potential solution to mitigate settlement problems. However, a comprehensive understanding of the geotechnical engineering properties of PU foam is crucial for effective design and injection work planning. This study focuses on a two-component PU foam composed of polyol and isocyanate, evaluating various geotechnical properties across different foam densities. Test samples were prepared by injecting PU foam into a vertical PVC cylinder to lift an internal piston. Key properties assessed include compressive strength (<InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40891_2025_638_Article_IEq1.gif" Format="GIF" Height="12" Rendition="HTML" Resolution="72" Type="Linedraw" Width="19" /> </InlineMediaObject> <EquationSource Format="TEX">$\sigma_{u}$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>σ</mi> <mi>u</mi> </msub> </math></EquationSource> </InlineEquation>), secant modulus (<InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40891_2025_638_Article_IEq2.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="26" /> </InlineMediaObject> <EquationSource Format="TEX">$E_{50}$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>E</mi> <mn>50</mn> </msub> </math></EquationSource> </InlineEquation>), secant Poisson’s ratio (<InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40891_2025_638_Article_IEq3.gif" Format="GIF" Height="12" Rendition="HTML" Resolution="72" Type="Linedraw" Width="25" /> </InlineMediaObject> <EquationSource Format="TEX">$\nu_{\sec }$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>ν</mi> <mo>sec</mo> </msub> </math></EquationSource> </InlineEquation>), cyclic residual strain (<InlineEquation ID="IEq4"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40891_2025_638_Article_IEq4.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="32" /> </InlineMediaObject> <EquationSource Format="TEX">$\varepsilon_{cyN}$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>ε</mi> <mrow> <mi mathvariant="italic">cyN</mi> </mrow> </msub> </math></EquationSource> </InlineEquation>), yield vertical stress (<InlineEquation ID="IEq5"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40891_2025_638_Article_IEq5.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="18" /> </InlineMediaObject> <EquationSource Format="TEX">$\sigma_{y}$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>σ</mi> <mi>y</mi> </msub> </math></EquationSource> </InlineEquation>), compressibility indices, and coefficient of permeability (<InlineEquation ID="IEq6"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40891_2025_638_Article_IEq6.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="13" /> </InlineMediaObject> <EquationSource Format="TEX">$k$</EquationSource> <EquationSource Format="MATHML"><math> <mi>k</mi> </math></EquationSource> </InlineEquation>). Results show an increase in <InlineEquation ID="IEq7"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40891_2025_638_Article_IEq1.gif" Format="GIF" Height="12" Rendition="HTML" Resolution="72" Type="Linedraw" Width="19" /> </InlineMediaObject> <EquationSource Format="TEX">$\sigma_{u}$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>σ</mi> <mi>u</mi> </msub> </math></EquationSource> </InlineEquation>, <InlineEquation ID="IEq8"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40891_2025_638_Article_IEq2.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="26" /> </InlineMediaObject> <EquationSource Format="TEX">$E_{50}$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>E</mi> <mn>50</mn> </msub> </math></EquationSource> </InlineEquation>, <InlineEquation ID="IEq9"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40891_2025_638_Article_IEq4.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="32" /> </InlineMediaObject> <EquationSource Format="TEX">$\varepsilon_{cyN}$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>ε</mi> <mrow> <mi mathvariant="italic">cyN</mi> </mrow> </msub> </math></EquationSource> </InlineEquation>, and <InlineEquation ID="IEq10"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40891_2025_638_Article_IEq5.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="18" /> </InlineMediaObject> <EquationSource Format="TEX">$\sigma_{y}$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>σ</mi> <mi>y</mi> </msub> </math></EquationSource> </InlineEquation> with rising foam density, while <InlineEquation ID="IEq11"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40891_2025_638_Article_IEq3.gif" Format="GIF" Height="12" Rendition="HTML" Resolution="72" Type="Linedraw" Width="25" /> </InlineMediaObject> <EquationSource Format="TEX">$\nu_{\sec }$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>ν</mi> <mo>sec</mo> </msub> </math></EquationSource> </InlineEquation>, compressibility indices, and <InlineEquation ID="IEq12"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40891_2025_638_Article_IEq6.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="13" /> </InlineMediaObject> <EquationSource Format="TEX">$k$</EquationSource> <EquationSource Format="MATHML"><math> <mi>k</mi> </math></EquationSource> </InlineEquation> decrease. Additionally, at constant foam density, <InlineEquation ID="IEq13"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40891_2025_638_Article_IEq3.gif" Format="GIF" Height="12" Rendition="HTML" Resolution="72" Type="Linedraw" Width="25" /> </InlineMediaObject> <EquationSource Format="TEX">$\nu_{\sec }$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>ν</mi> <mo>sec</mo> </msub> </math></EquationSource> </InlineEquation> decreases with higher vertical stress, and <InlineEquation ID="IEq14"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40891_2025_638_Article_IEq4.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="32" /> </InlineMediaObject> <EquationSource Format="TEX">$\varepsilon_{cyN}$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>ε</mi> <mrow> <mi mathvariant="italic">cyN</mi> </mrow> </msub> </math></EquationSource> </InlineEquation> increases with cyclic stress ratio (<InlineEquation ID="IEq15"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40891_2025_638_Article_IEq15.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="42" /> </InlineMediaObject> <EquationSource Format="TEX">$CSR$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi mathvariant="italic">CSR</mi> </mrow> </math></EquationSource> </InlineEquation>) and the number of cycles (<InlineEquation ID="IEq16"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40891_2025_638_Article_IEq16.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="22" /> </InlineMediaObject> <EquationSource Format="TEX">$N_{c}$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>N</mi> <mi>c</mi> </msub> </math></EquationSource> </InlineEquation>). Regression analyses yield empirical formulas for predicting these properties, providing valuable insights for the utilization of PU foam in geotechnical applications.</p>

Impact of Density on Geotechnical Engineering Characteristics of High-Expansive Polyurethane Foam

期刊论文
发表日期：

2025年6月10日

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Tamonwan Seubpong,
Warat Kongkitkul,
Pornthep Thanalertpipat,
Pornkasem Jongpradist

摘要

Ground deformation induced by stress transfer from civil engineering structures often leads to settlement issues, impacting the performance of structures like roads, parking slabs, and factory floors. Polyurethane (PU) foam, known for its significant volumetric expansion, emerges as a potential solution to mitigate settlement problems. However, a comprehensive understanding of the geotechnical engineering properties of PU foam is crucial for effective design and injection work planning. This study focuses on a two-component PU foam composed of polyol and isocyanate, evaluating various geotechnical properties across different foam densities. Test samples were prepared by injecting PU foam into a vertical PVC cylinder to lift an internal piston. Key properties assessed include compressive strength ( $\sigma_{u}$ $σ_{u}$ ), secant modulus ( $E_{50}$ $E_{50}$ ), secant Poisson’s ratio ( $\nu_{\sec }$ $ν_{sec}$ ), cyclic residual strain ( $\varepsilon_{cyN}$ $ε_{cyN}$ ), yield vertical stress ( $\sigma_{y}$ $σ_{y}$ ), compressibility indices, and coefficient of permeability ( $k$ $k$ ). Results show an increase in $\sigma_{u}$ $σ_{u}$ , $E_{50}$ $E_{50}$ , $\varepsilon_{cyN}$ $ε_{cyN}$ , and $\sigma_{y}$ $σ_{y}$ with rising foam density, while $\nu_{\sec }$ $ν_{sec}$ , compressibility indices, and $k$ $k$ decrease. Additionally, at constant foam density, $\nu_{\sec }$ $ν_{sec}$ decreases with higher vertical stress, and $\varepsilon_{cyN}$ $ε_{cyN}$ increases with cyclic stress ratio ( $CSR$ $CSR$ ) and the number of cycles ( $N_{c}$ $N_{c}$ ). Regression analyses yield empirical formulas for predicting these properties, providing valuable insights for the utilization of PU foam in geotechnical applications.