This study investigates the application of the horizontal stratified mining method to the extraction of steeply inclined unstable coal seams at the Puxi Mine. The stress environment in the mining area, the relationship between the supports and surrounding rock, the control of the rock layers in the caving zone, and the mechanical analysis of the roof collapse following the extraction of the steeply inclined coal seam were examined. The stress conditions in the mining area under the horizontal stratified mining method were explored, and a numerical analysis model was established using FLAC3D software, based on the rock mechanics parameters of the Puxi Mine’s rock layers and strata. The results indicate that, in the stress environment of the horizontal stratified mining method, the mining area is subject to not only the self-weight stress from the surrounding strata, large horizontal ground stresses, and gas pressures, but also concentrated stresses in both the dip and strike directions. When using this mining method, the stability of the two sides of the tunnel is generally good due to the surrounding rock being of a relatively stable nature. However, the roof collapse in the upper layers during the extraction of the lower layers is one of the factors affecting the safety of the support structures in the lower layers, necessitating enhanced support management. Deformation is expected in the mining face of the lower layers during extraction, and measures must be taken to prevent any instances of roof spalling. Therefore, the horizontal stratified mining method is considered feasible for the extraction of steeply inclined unstable coal seams at the Puxi Mine.

Prestressed concrete continuous box girder bridges have been widely adopted in transportation engineering due to their superior crack resistance ($Kf\geq$ 1.15) and stiffness stability ($\eta \leq$ 0.85). To address the mechanical uncertainties introduced by non-orthogonal diaphragm arrangements, by taking a 3 × 35 m box girder bridge constructed using a staged simply-supported-to-continuous method as the object, detailed beam grillage models with both orthogonal and stepped diaphragms were developed using Midas Civil 2023. Four loading scenarios were defined based on the JTG 3362-2018 standard, and static load tests employing four tri-axle heavy trucks were conducted to validate the model reliability. A total of 36 strain gauges (sampling frequency: 10 Hz) and 12 laser deflectometers (accuracy: ±0.01 mm) were installed on the top and bottom slabs of the box girder, with loading efficiency controlled within 0.91–1.03. Comparative analyses of strain fields ($\varepsilon$), deflections ($\delta$), and shear lag effects were performed for both diaphragm configurations. The results demonstrated that, under maximum positive bending moment conditions, the longitudinal strain differential rate across the top slab for the stepped diaphragm configuration remained within 3.7%. The deviation in deflection at the support region under negative bending moments was $\Delta \delta$ = 1.2 mm, meeting the specified code limits (L/600 = 58.3 mm). The loading efficiency test (0.91–1.03) confirmed the equivalent load-bearing performance of the stepped diaphragm configuration, with the cracking safety factor ($Kf$ = 1.18-1.22) found to be consistent with that of the orthogonal diaphragm model. A diaphragm inclination–stiffness matching criterion was proposed in this study, offering a theoretical reference for the design of the girder bridges constructed using a staged simply-supported-to-continuous method.

The surface hardness and estimated compressive strength of Lumle Rock (Pahara), situated in the Annapurna Rural Municipality of Kaski District, Nepal, were investigated using the Schmidt hammer (rebound hammer) test, a standardized non-destructive testing (NDT) method. This technique was employed to evaluate the geomechanical properties of the rock formation with specific attention to its potential for recreational rock climbing and site-specific geotechnical applications. Rebound values were collected in situ and statistically analyzed to determine characteristic strength at confidence intervals of 80%, 90%, and 95%, following the guidelines of IS 13311-Part 2. Critical factors influencing rebound measurements, including aggregate mineralogy, surface texture, moisture content, carbonation effects, and weathering conditions, were systematically considered and controlled where applicable. The results indicated that Lumle Rock (Pahara) exhibits sufficient surface hardness and mechanical integrity to support rock climbing activities. However, to ensure climber safety and to inform potential engineering uses, it is recommended that further subsurface investigations, including calibration, be conducted. The application of Schmidt Hammer testing in this context demonstrates the value of rapid, cost-effective assessment methods for evaluating the mechanical suitability of natural rock formations for recreational and civil engineering purposes.