This study first reviewed theories of the mechanical response of structures under loading, and the discrete element method provides a route for studying mechanical response including elastic deformation and structure failure. However, the direct acquisition of the microscopic parameters from the governing equations of the discrete element method via experiments encounters challenges. One possible strategy to obtain these microscopic parameters is parameter calibration that are widely used by researchers. Secondly, the governing equations and failure criterion of the discrete element method are summarized, and the microscopic parameters that would be calibrated are pinpointed. Next, the principles of classical calibration methods of discrete element method are explicated in detail, alongside the validation and discussion of their properties. Lastly, this study examined the applicability of calibrated parameters and points out that the size ratio, porosity, maximum radius, and minimum radius of particles should be identical in both the geometric calibration model and that for applications.

Barrel-type structures are ubiquitous in industry and life. A novel construction platform of barrel-type structures is introduced, and it involves a multi-motor system. The synchronous control of multiple motors has great importance. To guarantee the high precision, high stability, and fast response for the collaborative control of multiple motors, this paper proposes a multi-motor cooperative control strategy. Firstly, a speed synchronization control structure between multiple permanent magnet synchronous motors (PMSM) is designed by way of the mean coupling control structure. Then, the conventional PID controller is improved by machine learning. Moreover, a radial basis function neural (RBF) network is introduced to the conventional PID algorithm for system identification processing, and the gradient descent algorithm is used for parameter updating. An improved variable speed integral term is introduced into the integral term of the conventional PID algorithm to eliminate the error as soon as possible. Finally, it is verified via numerical simulation experiments that show the multi-motor cooperative control strategy has high anti-interference ability and robustness.

To more comprehensively explore the mechanism of the active freezing and thawing process of a new tube–curtain freezing method in construction, the temperature field of the new tube–curtain freezing process is analyzed using finite element software to establish a numerical model. Six paths were set up upstream and downstream of the model and around the top steel tube to analyze the development of frozen soil curtains during active freezing and forced thawing. The results show that, due to the effect of seepage, the cold energy generated by the upstream frozen pipe will be carried to downstream by water, which leads to the asymmetry of the frozen soil curtain. A greater seepage rate leads to a more pronounced the influence on the development of the temperature field. During the process of forced thawing, the first 15 days of the frozen soil curtain heating rate are fastest; thus, it is necessary to monitor the thawing settlement intensively during this period. By comparing different heads of water and different forced thawing temperatures, it was found that a bigger head of water results in a longer thawing time. At a constant head of water, a higher thawing temperature results in a shorter thawing time, with the thawing time at 50 °C being about 0.5 times that at 5 °C. Low-temperature thawing can be chosen to control the cost; however, when the head of water is large, high-temperature thawing can significantly shorten the thawing time. In addition, the new tube–curtain freezing method has little influence on the surrounding environment, along with a short construction period and low construction cost, in accordance with the concept of sustainable development.

In the construction of large-scale caissons, it is difficult to obtain accurate values of the end resistance. There are also inclination, sand boiling, and other issues. In this study, a simplified calculation model for the broken-line end-bearing capacity was proposed on the basis of the passive extrusion failure theory of foundations. Simplified calculation formulas for the bearing capacity under different soil support conditions were established, considering the impacts of excavation or burial depth on the failure slip surface and bearing capacity of the foundation. In addition, the impacts of different shapes of caisson components on the end resistance were analyzed. On the basis of this analysis, a bearing capacity correction coefficient was introduced that considers three-dimensional spatial effects; the calculation results of the end resistance method deviate from the on-site measured earth pressure values by no more than 10%. The dominant influences of the inclining moment and resisting moment on the caisson’s attitude varied progressively as the caisson continued to sink. In the construction of large-scale caissons, end resistance emerged as the primary factor governing the caisson’s orientation. Accordingly, a “stepped progressive” sinking control method was developed and implemented during the caisson sinking operations for Pier No. 5 of the Changzhou-Taixing Yangtze River Bridge. By actively controlling the width of the supporting soil at the end of the caisson and the burial depth, the verticality of the caisson throughout the construction process remained within 1/150. The verticality of the final sinking of the caisson exceeded 1/2000, and the torsional angle of the final sinking of the caisson was only 0.07°. This achieved the active control of the end resistance of the large caisson, the process of sinking, the attitude during the sinking, and the risk of sand boiling.

The artificial freezing construction technology, compared to other methods, offers several advantages, including superior waterproofing capabilities and the absence of environmental pollution. This technique is particularly prevalent in the construction of tunnels in challenging environments, where the dynamics of the freezing temperature field during the freezing process have consistently been a key area of interest during actual construction activities. In the Sanya Estuary Channel Submarine Tunnel Project, a three-dimensional transient model was developed using COMSOL finite element software to deeply analyze the formation and temperature distribution of the permafrost curtain. Two alternative schemes were designed to improve the original design by optimizing the layout of the permafrost pipeline. Comparative analysis shows that the isotherm −10 °C intersected at 14 days in the original scheme, 23 days in Optimized Scheme 1, and 24 days in Optimized Scheme 2, indicating a 10-day delay in Scheme 2 versus the original, yet still meeting the 25-day deadline. After 40 days of active freezing, the greatest difference in permafrost curtain thickness was observed at the east wall (downstream), with Scheme 2 differing by 1.05 m from the original and by 0.23 m from Scheme 1. Scheme 2 achieved an average permafrost curtain thickness of 4.18 m around the tunnel, exceeding the 3.5-m design requirement. The mean temperatures in the strong and weak freezing zones of Scheme 2 were below −10 °C and −8 °C, respectively, aligning with design standards. Given the conservative nature of the initial plan, Optimized Scheme 2 is highly practical for implementation and offers significant cost savings.