The high water content of soft soil leads to complex sedimentation, consolidation, and permeability characteristics, posing challenges to engineering design and construction. Although existing research has made progress in the field of consolidation and settlement characteristics, discussions on the low stress stage are still insufficient, and there is a lack of appropriate mathematical models to describe it. At the same time, the correlation and differences between the degree of consolidation used for settlement calculation and the degree of consolidation used for pore water pressure calculation have not been fully clarified. This study improves the measurement method for permeability coefficients and optimizes consolidation equipment, conducting research on the permeability and consolidation characteristics of soft soil with high water content. The research results show that soft soil with high water content exhibits significant consolidation settlement under low stress, and the incremental settlement decreases with the increase of consolidation stress. The void ratio and compression coefficient undergo drastic changes during consolidation, with a difference of 2 to 4 orders of magnitude, especially significant during the low-pressure stage. This study indicates the existence of a critical stress of about 4 kPa and proposes a segmented method to describe the consolidation and permeability characteristics of soft soil with high water content, establishing an e-lg sigma-lgk relationship model, which can effectively reflect the consolidation behavior of super-high water content soft soil. At the same time, the study also finds that in practical engineering applications, the degree of consolidation used for settlement calculation and the degree of consolidation used for pore water pressure calculation should be considered comprehensively to more accurately predict the consolidation process and guide construction.

The current research primarily focuses on the impact of full-ring expansion on tunnel safety, but the relationship between local expansion of the surrounding rock and initial water content is rarely studied yet. Therefore, this paper analyzes the mechanics and deformation characteristics of a tunnel passing through an expansive mudstone area in a tunnel project in China. The analysis considers different local expansion areas and the initial water content of the surrounding rock. The research findings indicate that the local expansion of the tunnel's vault and sidewall has the most significant impact on the deformation range of the surrounding rock. Compared to other expansion conditions, the deformation difference can reach a maximum of 156 mm. The order of expansion conditions leading to the development of plastic zone volume in the surrounding rock is as follows: full-ring expansion > vault expansion > local vault expansion > sidewall expansion > invert expansion. When the initial water content reaches a certain level, the expansion effect becomes less significant due to the upper limit of the surrounding rock's expansion capacity. However, an increase in water content will cause the surrounding rock to soften and intensify the expansion of the deformation range. The local expansion of the surrounding rock not only increases the bending moments on the preliminary lining at the directly affected by the expansive force but also significantly impacts other expansion areas. The local expansion of the vault and sidewall greatly influences the stability of the secondary lining, resulting in some areas having a safety factor lower than the allowed value. However, from the perspective of overall tunnel safety, the secondary lining still provides a certain safety margin.

Utilizing casein in geotechnical engineering and construction can reduce global dairy waste. Variations in initial water content during sample preparation influence cation and OH ion availability, alkaline additive concentrations, casein binder function, and rheological properties of the casein solution. This study investigates the impact of initial water content and casein solution rheology on unconfined compressive strength in two soil types (coarse and fine) treated with casein, both in dry conditions and after water immersion. The study also assesses the long-term performance of casein-treated soil under bio-decomposition. Results suggest that increasing casein content, beyond the optimal ratio, can enhance strength by adjusting initial water concentration. Notably, calcium caseinate-treated soil shows improved water resistance, with wet strength reaching 833 kPa at 5% casein and 20% initial water content, due to reduced viscosity and better workability, resulting in a more rigid soil structure during preparation. We propose an empirical formula describing the influence of casein solution rheological characteristics on soil strength. Furthermore, artificial neural networks, developed from experimental data, predict casein-treated soil strength, highlighting the significance of initial water content and rheological parameters.

This study first invents a novel oedometer apparatus for clay slurry, featuring a lightweight acrylic loading cap, a noncontact laser displacement sensor, and a 1:1 dead-weight loading system to improve traditional consolidation devices. The novel apparatus is then used to examine two clays: Hong Kong Marine Deposit and Kaolin clay. The loading with a minimum stress of 0.025 kPa is applied on samples with a maximum initial water content exceeding 9 times the liquid limit. Results demonstrate the S shape compression curves influenced by initial water contents, and the power-type relationships between permeability coefficient and void ratio. Empirical equations are obtained to determine the yield stress point based on initial water content and liquid limit. Higher initial water contents increase compression parameters (e.g., recompression index, Cr; compression index, Cc; and creep index, C alpha), though Cr/Cc and C alpha/Cc are almost in the normal range. The Cc of Kaolin clay with initial water contents above 3.5 times the liquid limit is significantly relevant to effective stress. Finally, a nonlinear creep model is enhanced and integrated into the finite strain consolidation equations, effectively simulating the oedometer tests and a self-weight consolidation test of clay slurry with nonlinear consolidation characteristics.

Transmedia migration of water is the key factor influencing the bond and shear mechanical properties of the interface system between soil and concrete. In numerous engineering projects, failures often occur at the soil-concrete interface, making the study of transmedia water migration in soil-concrete interface systems highly significant. This research based on the tracer properties of fluorescein to conduct a transmedia water infiltration test on silty clay-concrete interface systems. A fluorescent quantitative method was proposed to determine the moisture content within the concrete profile. The study investigated the migration of the wetting front, changes in water content, moisture distribution across the profiles of both media, and the spatial and temporal variations of soil moisture during the transmedia water migration process. The characteristics of transmedia water migration were compared under different initial soil water contents (IWC). Results demonstrated that the water distribution law of silty clay-concrete interface systems was not monotonous; notably, the water content in the interface area increased significantly. An increase in IWC inhibited the migration of the wetting front and the water content increment of the silty clay, while promoting the progression of saturation. Additionally, the water migration in the concrete was influenced by the silty clay. The proposed fluorescent quantitative method demonstrated high measurement accuracy.

The disintegration of expansive stiff clay will cause irreversible damage and deterioration of mechanical properties of the soil. The latest studies show that the disintegration is related to the swelling capacity of soil. In this study, a series of hydration disintegration tests and swelling pressure tests were performed on compacted Nanning expansive stiff clay samples with different initial water contents and dry densities. The observed disintegration process of all samples could be divided into initial, rapid and residual disintegration stages, among which the rapid stage dominated the whole process. By introducing relevant indicators to quantify the disintegration process, it was found that at a given dry density, the average disintegration rate of the sample decreased with increasing initial water content; while at a given water content, it decreased with increasing initial dry density. Such phenomena coincided well with the obtained evolution of swelling pressure at different initial water contents and dry densities. Based on these findings, the expansion-disintegration interaction mechanism of expansive stiff clay was finally analyzed from the perspectives of microstructure and hydration cracking. The initial conditions of the compacted samples determine the volume of inter-aggregates pores and thus the water transfer rate in soils, which affects the formation of hydration cracks. The cracking is induced by tension failure due to the expansion gradient formed during the hydration of sample, destructing the soil integrity to facilitate the disintegration. The disintegration, in turn provides preferential water infiltration channels to accelerate further soil expansion and hydration cracking. Such interactions proceeded until the completion of sample disintegration.

Exploring the interaction of pipe-soil under frost heave effect is the key to solving the problem of frequent damage to buried pipes. In this study, the effects of ambient temperature (AT), buried depth of pipe (BDP) and initial water content (IWC) on the interaction of pipe-soil under the condition of roadbed frost heave are studiedby experimental test. The results show that the buried pipe seriously affects the soil temperature field and the migration of pore water during roadbed frost heaving. As the AT decreases, the final strain of pipes (FSP) gradually increases, and the flatness of the roadbed gradually deteriorates. When the BDP is 2D (outer diameter of the pipe), the flatness of the roadbed is the worst. The pore water in unfrozen area tends to migrate more toward soil around pipes during the roadbed frost heaving. The IWC of roadbed has a greater impact on the FSP than the BDP These could provide a guidance for the construction of pipes under frost heave in roadbed.

Hydro -thermal coupling is the essence of the freeze -thaw process, and theoretical studies of this coupled process have been hot topics in the field of frozen soil. Darcy's law of unsaturated soil water flow, heat conduction theory, and relative saturation and solid -liquid ratio are based on this paper. According to the principle that the cumulative curve of particle gradation of canal foundation soil is similar to soil -water properties. A soil -water characteristic curve is derived using the cumulative particle gradation curve. VG model is then used to fit soil -water characteristic curves to obtain the canal foundation soil's hydraulic characteristic parameters, and the established hydro -thermal coupling model is modified to reflect canal foundation soil hydro -thermal evolution more objectively. A closed system one-way freezing test method is used to verify the feasibility of the proposed method in this part. The results show that the optimal parameters of the VG model of the subsoil are a = 0.06, n = 1.2, and m = 0.17, and the temperature and water fields obtained from the simulation are in good agreement with the measured data, showing the utility of the hydro -thermal coupling model in predicting hydraulic parameters. Analysis of the multi -field interaction mechanism and dynamic coupling process of the canal foundation soil during freezing and thawing. This has great importance for preventing freezing damage in canals and protecting agricultural safety.