Analysis of Unqualified Characteristics and Influencing Factors of Pile Foundation Static Load Tests in South China

As a concealed component of construction, the quality of pile foundations directly affects the safety of building structures; failure to pass static load tests may pose serious risks to construction quality. Addressing the frequent occurrence of failed static load tests for pile foundations in the complex geological regions of South China and the lack of systematic regional research, this paper examines 330 projects with failed static load tests (involving 427 non-compliant piles) in a district of Foshan City between 2013 and 2025 to investigate the characteristics of non-compliant piles and key influencing factors. Using statistical analysis and a text-based methodology involving “Extraction aided by large language models (LLM) – rule-based categorisation – manual review” the study performed structured processing of inspection reports, non-compliance lists, and code texts to identify technical characteristics and quality issues related to the five responsible parties. Using “responsible party–problem item” as the statistical unit, a total of 551 valid records were generated (with multiple responsible parties allowed per project). The results indicate that failures in static load testing primarily manifest as defects in pile integrity, abnormalities in the bearing layer, and instability at the pile-soil interface. According to the statistical analysis of problem records, the construction unit accounted for the highest proportion (32.49%), with issues concentrated in process stages such as borehole formation, borehole cleaning, and concrete pouring; issues with the construction unit (23.77%) and the supervision unit (18.87%) primarily involved deficiencies in process organization and oversight; while issues with the investigation (13.25%) and design (11.62%) units accounted for a lower proportion, they were closely related to deviations in bearing layer determination and mismatches in design parameters. Further analysis indicates that failure to meet static load requirements results from the combined effects of performance deviations across multiple entities and complex geological conditions such as karst and soft soil. The quality issue checklist and identification framework established in this paper can serve as a reference for improving pile foundation engineering quality in Foshan and similar geological regions in South China.