As a special geological phenomenon, the character of collapsible loess foundation is collapsible when penetrated by water. This character leads to the soil losing load bearing capacity largely and may lead to foundation failure. Pile is a popular foundation used in collapsible loess. The squeezed branch and plate pile is a new type of pile developed in recent years and has not be used in a project before. In this paper three squeezed branch and plate piles are tested in collapsible loess after immersion processing. The results may be used for reference in similar construction project, and to provide theoretical references for designing of the squeezed branch and plate piles in engineering practice.

To address the issues of poor fire and corrosion resistance in traditional steel structure reinforcement methods, the construction constraints of cast-in-place partially encased steel–concrete composite beams (PEC beams), and their difficulty in application for the rapid retrofitting of existing structures, this paper proposes a novel fully dry-assembled prefabricated partially encased steel–concrete composite beam (PPEC beam). This structure reliably connects prefabricated concrete beams to an H-shaped steel beam using bolts, achieving an efficient, dry, and cast-in-place-free reinforcement method. To investigate its flexural mechanical behaviour and failure mechanism, one cast-in-place PEC control specimen and three PPEC specimens with different connection and assembly configurations were designed. Four-point static bending tests were conducted to systematically analyse the failure modes, load–deflection curves, cross-sectional strain distributions, and ultimate load-bearing capacity. The results indicate that the PPEC beams exhibit comparable flexural capacity to the cast-in-place PEC beam, demonstrating excellent overall composite action. The flange-bolted connection achieves stronger steel–concrete composite action, with elastic stiffness essentially identical to that of the cast-in-place specimen. The web connection provides weaker restraint against local buckling of the steel flange, resulting in slightly lower elastic stiffness. The fully prefabricated assembled specimen shows significantly better plastic deformation capacity than the segmentally assembled specimen. The ultimate loads of all specimens exceed the code-predicted values. The proposed PPEC beam, with its convenient construction and reliable mechanical performance, is suitable for the reinforcement, retrofitting and replacement of simply supported secondary steel beams, working platform beams, and walkway beams.

To study the anchoring performance of a self-drilling anchor in sandy gravel strata, the influence of different anchoring lengths on the ultimate pull-out resistance of the self-drilling anchor was carried out through field tests, and the load-displacement curve was obtained. Based on this, combined with the indoor grouting test, an indoor orthogonal test scheme in line with the construction technology of the self-drilling anchor was designed, and the effects of different fine particle proportions, grouting pressures, and water-cement ratios on the pull-out peak, ultimate displacement, anchor diameter, and equivalent bond strength were analyzed. The results indicate a critical value of the self-drilling anchor in the sandy gravel strata. In the field test and indoor test, the failure mode of the bolt is the failure of the interface between the anchor body and the soil, and the trend of the load-displacement curve of the bolt is the same. Through an orthogonal test, it was found that the proportion of fine particles has the greatest influence on the anchorage performance of the self-drilling bolt. With the increase in the proportion of fine particles, the peak value of pull-out decreases, indicating that the self-drilling bolt exhibits better anchorage performance in soft soil layers, such as sandy gravel strata.