Experimental And Theoretical Studies On Non-Monotonic Compression And Consolidation Of Soft Soil

In the practical project of geotechnical engineering, the non-monotonic consolidation problems of soil are often encountered when subsoil is subjected to a non-monotonic increasing loading. Though the consolidation theory has been developed for eighty years and made a great achievement in the theoretical field, the compressibility of subsoil is still just taken as a constant in the process of loading, unloading and reloading, which is not consistent with the truth of practical engineering. In this dissertation, the one-dimensional consolidation theory involved with non-monotonic compression is studied systemically through laboratory testing and theoretical investigation. The main original work and results are as follows:1. The functions and features of GDS advanced consolidation testing system (GDSACTS) are investigated, and a program GDSDA is developed for test data fast processing. One-dimensional consolidation and permeability tests are conducted with 13 groups of Xiaoshan clay by GDSACTS to investigate its compressibility and permeability. It shows that both e - log₁₀ p and e - log₁₀ k_v relationships are linear.2. The compression test of loading-unloading-reloading combined with permeability test as well as the ones under cyclic loading are respectively made with 3 groups and 9 groups of Xiaoshan clay samples by GDSACTS, and the behavior of compression and permeability under non-monotonic compression is studied and the relevant geotechnical parameters representing the property of the clay in the process of loading and unloading are obtained. The test results show that, under the condition of non-monotonic compression, the linear relationships of e-log₁₀ p and e-log₁₀ k_v are also true, but their slopes are different with loading or unloading.3. Considering the variable compression coefficient under loading and unloading, a one-dimensional linear consolidation model is established and solved by semi-analytical method. The corresponding computer program is developed to analyze the behavior of one-dimensional consolidation of soft soil under non-monotonic compression in detail. The...