Pile foundation technology. Pile foundation technology has evolved from the small-diameter, low-bearing-capacity, highly polluting pile types of the early 1990s to today's large-diameter, ultra-long, rock-socketed, high-bearing-capacity, environmentally friendly, pollution-free and low-pollution pile types. For example, driven cast-in-place piles reach a maximum diameter of Φ800 mm and a length of over 30 m; PC piles (prestressed concrete pipe piles) and PHC piles (prestressed high-strength concrete pipe piles) reach Φ600 mm; bored and punched cast-in-place piles reach Φ1500 mm, with pile lengths up to 91 m and ultimate single-pile bearing capacities of over 30000 KN. At the same time, new pile types such as small-section piles and squeezed-expanded cast-in-place piles, as well as new construction techniques such as pile-tip grouting, water jetting, and pre-boring for pile driving, have been developed. Their technical features are as follows: First, to meet high bearing capacity requirements, large-diameter and ultra-long piles have been vigorously developed. Second, to meet the needs of old city renovation and underpinning reinforcement, small-section piles such as small-section static-pressure piles and anchor-rod static-pressure piles have been developed (pile diameter d≤250 mm, length-to-diameter ratio up to 100). Third, to solve environmental problems, new piles with low vibration, low soil displacement, no noise and no pollution, such as static-pressure piles, dry-excavation soil removal and full-casing drilling rigs, have been developed and applied. Fourth, to fully utilize the bearing capacity of foundation soil, reamed piles and squeezed-expanded branch/plate piles have been developed and applied. Fifth, to reduce pile cross-sections and improve pile shaft strength, high-strength piles such as PC piles, PHC piles and steel pipe piles have been developed.

Ground treatment technology. In the early 1990s, ground treatment technology for buildings in our province developed rapidly. Ground treatment technologies such as cement-soil mixing piles, gravel piles, sand piles, preloading consolidation and dynamic compaction, as well as geotechnical materials, were quickly promoted and applied, and certain experience was gained, along with many lessons learned. In the late 1990s, most of these technologies in building construction were replaced by pile foundations, their application volume dropped greatly, and they shifted in large numbers to infrastructure construction such as municipal and transportation projects. At the same time, technologies such as fly ash gravel piles for reinforcing soft foundations of high-fill embankments, high-power cement-soil mixing piles (60 kW) and high-power vibroflotation technology (55 kW) were developed. High-pressure jet grouting piles are widely used for water-stop curtains in flood control projects and foundation pit projects, and are also commonly used for foundation reinforcement of existing buildings. In terms of ground treatment technology, our province has generally reached the domestic advanced level, with some aspects at the leading level. Its technical features are as follows: First, geotechnical materials are used for vertical and horizontal reinforcement and slope surface treatment in soft foundation treatment. Second, geotechnical reinforced cushions are widely used in shallow ground treatment to improve the horizontal tensile capacity, sliding stability and uniform deformation of soil layers. Third, densification treatment processes for loose foundations such as fill and miscellaneous fill have developed greatly, adopting dynamic compaction, vibroflotation, compaction-vibration and other methods. Fourth, mixing piles have made considerable progress in reinforcement depth, mixing diameter and scope of application; the mixing process adopts a combination of mixing and jet grouting supplemented by automatic control and management devices, making it suitable for harder soil layers and improving quality levels.

Rational use of natural foundations and development and application of composite foundations with granular material piles, flexible piles, semi-rigid piles and rigid piles have been successfully applied in general multi-story buildings, small high-rise buildings and medium-high-rise buildings, among which the tallest building reached 30 stories.

Foundation pit and slope support technology. Since the 1990s, a large number of high-rise buildings have been continuously constructed, and foundation pits have become a hot issue in engineering construction. Due to the particularity of the coastal geology of our province, foundation pit and slope support technology has also developed quite rapidly, forming some support types suited to the characteristics of our province, including diaphragm walls with internal bracing, row piles with internal bracing combined with water-stop curtain technology, cement-soil gravity retaining structures, anchored row pile support technology, soil nail wall support, anchor-shotcrete support and combined support structures. For example, shotcrete-anchor support was first applied in soft soil foundations and developed into a combined support with micro-piles, successfully solving the problem of pit wall stability when applying shotcrete-anchor support in soft soil; in a foundation pit in Xiamen with an excavation depth of 16—18 m, row piles with prestressed anchor cables were adopted; the foundation pit of Yuanhong City in Fuzhou (Phases I and II) has an area of nearly 20000 m2 and is located in sandy soil at the edge of the Minjiang River, with an excavation depth of 11 m at the edge of the embankment, adopting a combination of cutoff dewatering and multiple support forms; four foundation pit projects in Fuzhou, including World Golden Dragon, successfully adopted diaphragm walls with internal bracing and top-down construction, etc.

Testing and monitoring technology. Over the past decade or more, through introduction and development, our province has reached a new level in pile foundation testing technology and geotechnical engineering monitoring, obtaining some valuable data and making important contributions to the study of geotechnical engineering technology and the improvement of design levels in our province, with some aspects in a leading position.