Abstract This study investigates the suitability of the swelling and collapse theory proposed based on a constitutive virgin compression surface (VCS) developed within the modified Monash Peradeniya Kodikara (MPK) framework. The modified MPK approach incorporates net stress, void ratio, and moisture ratio as state variables to interpret the swelling-collapse behavior of unsaturated soils. The soil selected for this research was an expansive Quaternary age basaltic residual clay located in Victoria, Australia. The experimental program included testing on unsaturated compacted clay specimens and clay specimens stabilized with lime at the optimum lime content (OLC). The OLC was obtained based on the swelling potential. Static compaction tests were conducted on untreated and lime-treated samples to establish the VCS and to propose the relationship between moisture ratio and net stress. Next, 1-D compression and consolidation laboratory tests were carried out to investigate and compare the mechanism of collapse and swelling based on well-established suction-based theories and the moisture content-based approach of this research. The swelling and collapse response obtained through both theories were very close which verified the suitability of the moisture content-based approach, being the Modified MPK framework. This study also investigated the application of suction-controlled experimental data extracted from the relevant literature within the modified MPK framework. The novelty of this study is proposing and validating a framework for conversion of the results between two different partial theories to interpret the volumetric behavior of expansive clay. Finally, a new method is proposed to estimate the swelling-collapse state of a sample through wetting without the need to establish the VCS.

中文翻译：

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基于原始压缩表面提出的膨胀和坍塌理论的适用性

摘要 本研究调查了基于在改进的 Monash Peradeniya Kodikara (MPK) 框架内开发的本构原始压缩表面 (VCS) 提出的膨胀和坍塌理论的适用性。改进的 MPK 方法将净应力、孔隙比和水分比作为状态变量来解释非饱和土的膨胀-塌陷行为。本研究选择的土壤是位于澳大利亚维多利亚的膨胀的第四纪玄武岩残余粘土。实验计划包括对不饱和压实粘土试样和在最佳石灰含量 (OLC) 下用石灰稳定的粘土试样进行测试。基于溶胀潜力获得OLC。对未经处理和石灰处理过的样品进行静态压实试验，以建立 VCS 并提出水分比和净应力之间的关系。接下来，进行一维压缩和固结实验室测试，以研究和比较基于成熟的吸力理论和本研究基于水分含量的方法的坍塌和膨胀机制。通过两种理论获得的膨胀和坍塌响应非常接近，这验证了基于水分含量的方法的适用性，即改进的 MPK 框架。本研究还调查了从相关文献中提取的吸力控制实验数据在修改后的 MPK 框架内的应用。这项研究的新颖之处在于提出并验证了一个框架，用于在两种不同的局部理论之间转换结果，以解释膨胀粘土的体积行为。最后，提出了一种新方法，无需建立 VCS，即可通过润湿来估计样品的溶胀-塌陷状态。