Foundation pit excavation is common in urban construction, while safety evaluation is always significant in every specified project. The soil material properties, groundwater level, excavation method, supporting structure, monitoring points’ arrangement, and so on distinguish from one site from another. Thus, many studies have looked into the safety and reliability of designated projects. This paper was based on the co-construction underground tunnel project of a deep foundation pit excavation in Suzhou, China. This paper aimed to perform a safety evaluation on this foundation pit by means of numerical simulation for parameter influence analysis, as well as scientific comparison with in-site monitoring data. To minimize the energy consumption and contribute to the carbon neutrality, a brief energy consumption analysis was also conducted. The results indicated that the maximum deformation of the foundation pit bottom is 4.5 cm and the deformation of the foundation pit is within the allowable range. The maximum horizontal displacement of each excavation is approximately at 10 m to 12 m of the diaphragm wall and the largest deformation is 28 mm. The maximum ground settlement is less than 16 mm, which confirmed the safety during excavation. It is ideal that the above deformation law will provide a reference for similar projects. Furthermore, this research simulated and monitored the whole cycle of foundation pit excavation, and contributes to savings in energy consumption and limiting of carbon emissions.

Nuclear energy is a double-edged technology, which has a significant role in the chemical industry, but may bring about radioactivity and destruction. The 2011 Fukushima nuclear power plant accident caused by a tsunami, which flooded and led to tens of millions of disaster debris and tsunami deposits, severely disrupted the electricity supply in Japan and induced USD 211 billion worth of direct economic losses. Cs⁺ was easily dissolved in this accident, had a high chemical activity, and thus required an appropriate adsorption method. Zeolite is an effective removal adsorbent, which is suitable to be investigated. The present study uses natural zeolite and three inorganic modified zeolites. Furthermore, the effects of various factors are investigated. Kinetic models and the isothermal adsorption mechanism are also conducted. For microscale studies for the adsorption mechanism, scanning electron microscope (SEM) and X-ray diffraction (XRD) were involved in the study. The results indicate that the optimal dosage is 1.1 g and the maximum adsorption rate is around 80%. An alkaline environment is more conducive to the occurrence of adsorption. As for the isotherm and kinetic studies, the data fits better with the Redlich–Peterson isothermal model and intragranular diffusion model. In this small-scale experiment, the highest adsorption capacity was for Mg-zeolite at 6.53 mg/g. Finally, Mg-Zeolite presents the best adsorption capacity.

Bentonite, with excellent osmotic swelling performance and low hydraulic conductivity, represents as an ideal material for the final disposal of radioactive wastes. This paper investigates bentonite and three inorganic modified bentonites (Na-Bentonite, K-Bentonite and Mg-Bentonite) in adsorption of Cs+, one of the major hazardous metals in radioactive waste. The effects of solution pH value, sorbent dosage and initial concentration on the adsorption performance of Cs+ were investigated, as well as the effects of temperature and reaction time on the adsorption capacity and removal rate of heavy metal Cs+. The internal structure and chemical composition of bentonite before and after adsorption were also discussed. The results indicate that the maximum adsorption rate is 95.30%, and the estimated best adsorption capacity is almost 28.2 mg/g. 1.1 g bentonite dosage and 1.0 mol/L solution concentration in alkaline environment is the most suitable conditions for cesium adsorption reaction, which can be witnessed in Na-Bentonite.

Soil bentonite (SB) mixtures generally presents inadequate mechanical properties compared to other cutoff wall materials. Since both deformability and a certain level of strength properties need to be achieved for static loads or in situations of dynamic loads, the cement amendment is adopted to improve the engineering performance and ensuring the long-term effectiveness of SB cutoff walls. This study investigated the strength properties and deformation characteristics of soil-bentonite mixtures amended with slag cement using Consolidated-Undrained (CU) triaxial tests. The contents of slag cement powder considered were 25, 50, and 75 kg/m³. The test results indicate that the undrained shear strength, residual shear strength and effective strength parameters are significantly influenced by the integration of cementation and consolidation. As compared in different cement addition, the 25 kg/m³ cement amended specimens shows strain-hardening behaviours, 42.7 to 65.1 kPa undrained shear strength in ductile failure mode with no discernible cracks, which signifying plastic deformation with high deformability under triaxial loading. This implies that, although the contents of the slag cement were not so high, such as 25 kg/m³, the amended soil-bentonite performed high strength and deformability. <!----> <!----> <!----> <!---->