According to the practice of vertical shaft engineering, two types of composite structural model specimens of steel beam and slab are designed and made. According to whether shear connectors are set between steel skeleton and concrete slab, the two specimens are divided into two types: the shear model without spot welding of beam and slab, and the shear model with intesgral casting of beam and slab. Through the uniaxial static loading test at three-point bending, the flexural capacity of the structure was obtained, and the load-deflection curve and load-strain curve of the mid-span were plotted to analyze the failure characteristics. Through the comparative test, it can be seen that the installation of shear connectors can effectively improve the integrity of the structure and the flexural bearing capacity, delay the cracking time of concrete slabs and slow down the development of cracks. Reducing the height of the section can improve the stability of the structure and increase the utilization rate of the working space.

In order to explore the change of soil temperature field in the connecting channel of water rich soft soil layer during freezing construction, taking a connecting channel of Hangzhou Shaoxing intercity railway project as an example, the temperature field distribution and frozen wall thickness of the connecting channel are studied by using field measurement and numerical simulation. The results show that affected by the heat dissipation of the segments and the inclined arrangement of the freezing tubes, the thickness of the freezing wall will first increase continuously, then decrease slightly, and finally return to a gentle trend with the increase of the depth. When the depth is 2.192 m, the thickness of the freezing wall is the largest, and when the depth is greater than 6.640 m, the thickness of the freezing wall tends to be stable; The soil in the frozen area of the connecting channel can be divided into heat dissipation influence section, freezing pipe layout influence section and freezing stability section; The optimized laying mode of thermal insulation materials and the optimized segment structure can effectively improve the freezing effect of the soil near the segment end of the tunnel, and increase the thickness of the frozen wall at the bell mouth by about 53.8%.

Aiming at the state of affairs that the backside soil of the basis pit in the tender soil location is saturated smooth clay, the stability of narrow foundation pit under different insertion ratios is studied based on the slender foundation pit of a cable tunnel in a city of Fujian Province. Centrifugal model tests with three different insertion ratios were designed to simulate narrow foundation pit excavation, and the soil displacement and stable failure mode of foundation pit were observed. The results show that: When the insertion ratio is 1∶1 and 1∶0.8, the deformation of the retaining wall is small, and the deformation of the retaining wall indicates a drum-shaped deformation mode of "small at each end and giant in the middle. Whe insertion ratio is 1∶0.8, compared with the situation of insertion ratio is 1∶1, the deformation of the retaining wall enlarges slightly, which can meet the deformation requirements. It is more economical rationl when the insertion ratio is set to 1∶0.8. When the insertion ratio is 1∶0.67, the width effect of narrow foundation pit is lost due to the insufficient penetration depth of retaining wall. The retaining wall reveals an inverted "八" structure deformation pattern, a massive quantity of soil at the backside of the pit uplifts, and the basis pit is destroyed. Finally, the numerical simulation method is used for assessment and verification. The lookup consequences of this paper can notably optimize the insertion depth of slender basis pits, thereby decreasing engineering costs, saving development resources, and enhancing aid utilization efficiency.

High internal pressure can readily cause cracking in the underground cavern of compressed air energy storage (CAES), posing a significant threat to its stability and sealing. To effectively transfer internal pressure loads, enhance cavern deformation capacity, and leverage the bearing capacity of surrounding rock, we propose a flexible lining design using low-elastic modulus flexible concrete as the lining layer for CAES underground caverns. The mechanical properties of flexible concrete under various proportions are initially investigated through laboratory tests. Building on these findings, we propose a modified concrete damage-plasticity (CDP) constitutive model for flexible concrete and establish a mechanical calculation model for underground caverns utilizing flexible concrete. To demonstrate the feasibility of using flexible concrete in CAES underground caverns, this study compares the mechanical response of these caverns with different lining forms and varying flexible concrete ratios. This comparison is conducted within the context of an ongoing CAES underground cavern project. The results indicate that low-elastic modulus flexible concrete can effectively reduce tensile stress in the concrete lining of high-pressure CAES underground caverns. This stress reduction minimizes lining cracking, facilitates internal pressure load transfer, enhances cavern deformation capacity, and leverages the bearing capacity of surrounding rock.