To investigate the stress state at the joints of two-way reinforced concrete composite slabs, this study conducted static load tests on four two-way concrete composite slabs. The primary focus was on analyzing the effects of lap reinforcement length and cross-sectional height at the joints on the load-bearing capacity, deformation behavior, and crack development of the slabs. The experimental results revealed that increasing the lap reinforcement length and cross-sectional height at the joints significantly enhanced the overall integrity and flexural capacity of the composite slabs, with load-bearing capacity increasing by up to 92.3% and deflection decreasing by as much as 40.2%. Additionally, a finite element model was used to simulate the mechanical behavior of the composite slabs, and the results were compared with experimental data, showing an error margin of within 10%. Based on the validated finite element model, the study further explored key factors influencing the stress performance at the joints of two-way concrete composite slabs and their impact patterns. Finally, the paper proposes a simplified formula for calculating the load-bearing capacity of composite slabs, which enables rapid estimation of slab performance, providing theoretical support and practical guidance for structural engineering and construction practices.

The stability of the gas extraction roadway is very important for the safe mining of coal and gas. The compression arch formed by the combined action of the prestressed bolt (cable) support and surrounding rock has been widely used in the engineering practice of the gas extraction roadway. It is of great engineering application value to analyze the influence of prestressed bolt (cable) parameters on the compression arch. In this paper, combined with the engineering practice of the deep roadway in Huainan and Huaibei mining area of Anhui Province, the mechanical parameters of surrounding rock are measured via field coring and the laboratory. The numerical simulation software FLAC^3D is used to analyze the typical position of fractured mudstone, mudstone, sandy mudstone and muddy sandstone under the bolt pre-tightening force of F = 50 kN, 70 kN and 100 kN; the bolt spacing of a × b = 400 mm × 400 mm, 500 mm × 500 mm and 600 mm × 600 mm; the bolt length of L = 1500 mm, 2000 mm, 2600 mm and 3000 mm; and the distribution characteristics of additional compressive stress on the surface of the side. The influence of the different lithology and bolt parameters on the thickness and strength of the compression arch was analyzed, and on this basis, prestressed anchor cables with a pre-tightening force of F = 80 kN, 100 kN and 120 kN and length of L = 3000 mm, 4000 mm and 6000 mm were applied, and their influence on the thickness and strength of the compression arch was analyzed. The results show that the bolt pre-tightening force (F) and the bolt length (L) have a significant effect on the thickness of the compression arch, while the surrounding rock lithology, the bolt spacing (a × b), the anchor cable pre-tightening force (F) and the anchor cable length (L) have no obvious effect on the thickness of the compression arch. The surrounding rock lithology, the bolt pre-tightening force (F), the bolt length (L), the bolt spacing (a × b), the anchor cable pre-tightening force (F) and the anchor cable length (L) have a significant effect on the strength of the compression arch.

It is challenging to assure safe and effective gas mining due to the surrounding soft coal rock and rock roads in deep and high gas mines being extremely loose and broken. One of the effective ways is to arrange pre-stressed anchors in a certain area of the roadway surrounding rocks to form a compression arch with the joint action of anchors and surrounding rocks, but due to the lack of in-depth systematic research on the formation mechanism of the compression arch, the effect is difficult to give full play. The typical microstructure of deep soft coal and rock was observed by the borehole camera method, and the mechanical performance parameters were measured in the laboratory. The distribution characteristics of different bolt spacing, bolt pre-tightening force, and bolt length along the bolt arrangement direction and the additional compressive stress on the surface of the straight wall of a semi-circular arch deep soft coal and rock roadway were numerically simulated and analyzed. According to the uniform distribution range and size of the small fluctuation of the additional compressive stress inside the coal and rock, the distribution and size of the additional compressive stress on the surface of the straight wall and the effective superposition of the additional compressive stress, and the thickness and strength of the compression arch of the deep coal and rock preload bolt were analyzed, and the reasonable parameters of the pre-stressed bolt were determined. The results show that bolt spacing, pre-tightening force, and bolt length significantly affect the thickness and strength of the compression arch. The reasonable spacing of the pre-stressed bolt was a × b = 600 mm × 600 mm~400 mm × 400 mm, the pre-stressed bolt pre-tightening force was F = 50~90 kN, the length of the pre-stressed bolt was L = 1500~2000 mm, the strength of compression arch was $\Delta {\sigma }_{\mathrm{c}}$ = −1.480~−1.589 MPa, and the thickness of the compression arch was m = −266.67~−533.33 mm.

A static performance experimental study was conducted on six simply supported reinforced concrete truss hollow composite slabs to analyze their flexural rigidity. The study investigated the effects of the slab thickness, the dimensions of the hollow thin-walled boxes, and the composite interfaces on the flexural rigidity of the hollow composite slabs. The flexural rigidity was calculated using methods from American standards, Chinese standards, and the relevant literature, and the results were compared with the experimental data. Based on the experimental findings, a method for calculating the flexural rigidity of hollow composite slabs using a reduced moment of inertia equation was proposed, and the calculated results showed good agreement with the experimental results. The research indicates that the composite interface and the size of the hollow thin-walled boxes have minimal influence on the flexural performance of hollow composite slabs, while the slab thickness significantly impacts their flexural performance. By employing the effective moment of inertia method and substructure calculation theory, a calculation method for the flexural rigidity of hollow composite slabs was established, demonstrating high accuracy.