The thermal effects on the pore-water pressure and strength behavior of marine sediments from the South China Sea were studied by using temperature-controlled triaxial shear tests on reconstituted specimens. The experimental program included consolidation at a temperature of 5°C, undrained and drained heating from 5°C to 50°C, and undrained triaxial shear at 5°C and 50°C. The results indicated that the normalized heating-induced pore-water pressure increased with increasing temperature at the undrained heating stage. The undrained shear strength of the specimens under undrained or drained heating was 14.1% lower or 11.2% higher than that of specimens at 5°C, respectively. The shear-induced pore-water pressure of the specimens under undrained and drained heating was lower than that of the specimens at 5°C by 60.5% and 20.3%, respectively. The increasing temperature caused an increase in the slope of the critical state line (M).

Due to the opacity of natural soil, transparent soil has become an effective research tool to visualize soil internal movements and deformations. In this paper, the past research on transparent soil samples were summarized and reviewed. Due to the incompatibility with the latex membrane, the high viscosity and the high cost of the previously used pore fluids in the mixtures of transparent soil samples, more chemicals, and their mixtures have been tested in search of more suitable pore fluids to overcome the shortcomings above. Both granular particles of silica gel and fused quartz were tested for possible transparent clay and sand samples, respectively. Among the 19 chemicals/oils/water tested previously, 7 of them were selected with another 8 new oil and 30 new chemicals have been tested. There were 19 mixtures of fluids (15 oil-based and 4 water-based) studied for suitable pore fluids to the target refractive indices (TRIs) of the two granular particles to achieve the transparency of soil samples. Both interactions of the potential pore fluids with latex membrane and with granular particles were measured. Potassium thiocyanaten (KSCN) solution was identified as one of the new suitable water-based solutions with low viscosity and easy researching TRIs. Ethanol versus 3-Propanetriol (E +3-P) mixture, and Isopropanol versus 3-Propanetriol (I +3-P) mixture were identified as two new suitable oil-based solutions with minimum interaction with latex membranes.

The temperature distribution around the offshore burial pipeline is an important factor affecting its safety design and economic operation. The traditional test method cannot obtain the continuous temperature distribution of soil owing to the constraints of placing measurement sensors in soil. The transparent soil model test is an alternative method to realize the visualization research of soil temperature. In this paper, a relationship between the temperature of transparent soil and pixel intensity was first established. Then, the transparent soil test and numerical simulation, considering the natural convection, were carried out to study the temperature distribution around the submarine pipeline during start-up and stable operation. The influence of buried depth and pipeline diameter was analyzed. The results suggest that the continuous temperature distribution can be obtained visually by using a transparent soil test, and the observed heating zone of influence extended to a radial distance of 2.6 pipe diameters. The numerical analysis results show that the influence zone of the temperature of pipeline is a distance of four pipeline diameters at a temperature difference of 45 °C. The buried depth and pipeline diameter have little influence on the influence zone. In addition, the contour curves of soil temperature around the pipeline with different diameter are similar in shape. With the decrease in the buried depth of pipeline, the temperature gradient of soil around the pipeline decreases, which is caused by the natural convection.

The bearing and deformation characteristics of monopile foundation under the monotonic and cyclic loads are key factors to consider in the design of the transmission tower structure or offshore wind energy converters. The model tests and numerical simulations of monopile foundation under monotonic and cyclic horizontal loads were performed in sand to explore the bearing characteristics and the deformation characteristics of pile. The potentially affected factors including loading height, relative density of soil, displacement amplitude were analyzed. The results show that with the loading height varies from 1 D to 4 D, the horizontal static bearing capacity of the pile under different the soil relative density decreased by 1.63–1.9 times, and the peak bending moment increased by 22.9%–36.8%. Under the cyclic loads, the peak load on the pile top increased by 31.7%–56.1% for each 1 mm increase in displacement amplitude. The stiffness of soil around pile varies as the number of cycles increases with the development trend of decreases first and then increases gradually. As the horizontal load and cycle number increase, the range of the displacement of soil extends towards the bottom of pile, until it covers the entire lower part of the model.