Pile foundation engineering
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Section 1: Overview and Objectives] Understanding: The working characteristics of pile foundations. I. Working characteristics of pile foundations Pile foundations are a foundation type that is both ancient and modern, and they are widely used in the construction of high-rise buildings and important structures. The function of a pile foundation is to transfer the large loads from the superstructure, through the piles, to deeper layers of solid soil, thereby overcoming the problems of insufficient bearing capacity and excessive deformation associated with shallow foundations. As shown in Figure 2-1 (Figure 2—1 on page 56 of the textbook). Pile foundation with high cap; Pile foundation with low cap. Figure 2-1: Pile foundations. Pile foundations feature high bearing capacity, low and uniform settlement, as well as a slow settlement rate. It can withstand vertical loads, horizontal loads, uplift forces, as well as the vibrations or dynamic forces generated by machinery, and is widely used in projects such as building foundations, bridges, and water conservancy structures. II. Classification of pile foundations In engineering, pile foundations are usually composed of several piles; a cap is placed at the top of these piles to connect them together and to distribute the loads from the superstructure evenly to the piles. Figure 2-1 1. Classification based on the height of the cap: ① Pile foundation with a high cap – the bottom surface of the cap is above ground level, and its stress and deformation characteristics differ from those of pile foundations with a low cap. It is generally used in bridge and dock projects. ②Low-capital pile foundation – the bottom surface of the cap is below ground level, and it is generally used in building construction projects. 2. Based on the nature of the load-bearing capacity: ① End-bearing piles – these are piles that pass through soft soil layers and transfer the loads of the building to the hard soil or rock layers at the pile ends. The frictional force exerted by the softer soil adjacent to the pile on the pile body is very small, and can be considered negligible. ②A friction pile is one that is driven to a certain depth into soft soil layers; through the friction between the pile side and the soil, the loads applied to the upper part of the pile are distributed throughout the soil surrounding it. The soil at the pile tip also provides some support. When the soil supported by the pile tip is not very compact and there is a certain relative displacement between the pile and the soil, then the pile functions as a friction pile. 3. Based on the material of the pile shaft: ① Reinforced concrete piles can be prefabricated or cast in place. According to the design, the length and cross-sectional dimensions of the piles can be chosen arbitrarily. ②Common steel piles include steel pipe piles with diameters of 250~1200 mm, as well as wide-flange I-shaped steel piles. Steel piles have high load-bearing capacity, making them convenient for lifting, transporting, driving, and connecting, but they require a large amount of steel and result in high costs. At present, it is only used in a few key projects in our country. In the project of Shanghai Baoshan Iron and Steel Plant, for the foundations of important and high-speed operating equipment as well as column foundations, a large number of steel pipe piles with diameters of 914.4 mm and 600 mm and lengths of around 60 mm were used. ③Piles are now rarely used, only in certain reinforcement projects or temporary structures where materials can be obtained locally. When below the water table, wood has good durability, but it is highly susceptible to corrosion in an environment with alternating dry and wet conditions. ④Sand and gravel piles are mainly used for foundation reinforcement and soil compaction. The No. 1 and No. 2 residential buildings in the East Campus of Huaibei Vocational and Technical College use gravel piles; the diameter of these piles is 533 mm, their shape is triangular, and the spacing between them is 1100 mm. The teaching buildings at the West Campus of Huaibei Vocational and Technical College also use gravel piles. ⑤Fly ash soil piles are mainly used for foundation reinforcement. 4. Classified by the functional purpose of the pile: ① Vertical compressive piles; ② Vertical tensile piles; ③ Piles for horizontal loads; ④ Piles subjected to combined stresses. 5. Classified by pile diameter: ① Small-diameter piles, d ≤ 250 mm; ② Medium-diameter piles, 250 mm < d < 800 mm; ③ Large-diameter piles, d ≥ 800 mm. 6. Classified by the method of hole formation: ① Non-displacement piles, such as slurry-supported cast-in-place piles and manually dug cast-in-place piles, which are widely used. ②Some soil displacement piles are drilled first and then driven in. ③Soil displacement pile, driven pile. 7. Classified by manufacturing process: ① Precast piles. Reinforced concrete precast piles are fabricated in factories or at the construction site, and are driven into the ground using methods such as hammering or vibration. ②Cast-in-place piles, also known as poured piles, involve drilling holes directly in the ground at the designated pile locations; a rebar cage may or may not be placed inside the hole, and then concrete is poured into the hole to form the pile. Compared to precast piles, it saves steel, and when the bearing stratum is uneven, the pile length can be designed according to actual conditions. 8. Classified by cross-sectional shape: ① Square-section piles are convenient to manufacture, transport, and store; the side length of their cross-section is generally 250~550 mm. ②Circular hollow piles are prefabricated in factories using the centrifugal rotation method; they feature material savings, low self-weight, and a large surface area. The domestic railway authorities already have standard products available; their diameter ranges from 300 mm, 450 mm, and 550 mm, the wall thickness is 80 mm, and the length of each section varies from 2 m to 12 m. This post was last edited by hhbwwy on 2009-3-26 11:27.]
Let’s all work hard to finish this book! This is a great book: “Practical Manual for Design, Construction, and Testing of Pile Foundations”. Chapter 1: Introduction. Section 1: Definition and classification of piles; Section 2: Challenges faced by pile foundation technology. Chapter 2: Performance of pile foundations under static loads. Section 1: Performance of single piles; Section 2: Performance of pile groups; Section 3: Piles subjected to negative skin friction; Section 4: Uplift-resistant piles and inclined piles. Chapter 3: Theoretical analysis of pile foundations. Section 1: Development of theories related to pile foundation analysis; Section 2: Analytical solutions using the linear elastic subgrade reaction method (M-method); Section 3: Numerical solutions based on the elastic subgrade reaction method; Section 4: Measures to enhance the horizontal bearing capacity of piles in elastic subgrades. Chapter 4: Geotechnical investigations for pile foundations. Section 1: Classification of construction sites; Section 2: Classification of buildings; Section 3: Requirements for geotechnical investigations in pile foundation projects; Section 4: Investigation of underground utilities and nearby structures. Chapter 5: Design of pile foundations. Section 1: General requirements for pile foundation design; Section 2: Relevant data required for pile foundation design; Section 3: Loads, load combinations, and load aggregation; Section 4: Indicators relating to the bearing capacity and cross-sectional dimensions of piles; Section 5: Ultimate states of pile foundations and their calculations; Section 6: Reliability analysis of pile foundations; Section 7: Contents and procedures involved in pile foundation design; Section 8: Theories and methods used in design calculations; Section 9: Depth and scope of design calculations; Section 10: Role of codes and standards in pile foundation design; Section 11: Theory of sparse pile arrangements; Section 12: Selection of pile types; Section 13: Principles governing pile layout; Section 14: Structural forms of pile foundations; Section 15: Geometric dimensions and structural features of piles; Section 16: Bearing capacity of pile foundations; Section 17: Settlement of pile foundations – Engineering examples. Chapter 6: Design of pile foundations under special conditions. Section 1: Design of pile foundations in soft soil layers; Section 2: Design of pile foundations in fill soils; Section 3: Design of pile foundations in loess regions; Section 4: Design of pile foundations in expansive soil areas; Section 5: Design of pile foundations in permafrost regions – Engineering examples; Section 6: Design of pile foundations in karst areas; Section 7: Design of pile foundations in seismic zones; Section 8: Design of pile foundations near water or underwater. Chapter 7: Use of pile foundations in subgrade engineering. Section 1: Determination of the bearing capacity of single piles; Section 2: Bearing capacity and settlement of pile groups; Section 3: Feasibility of driving piles and selection of appropriate hammers; Section 4: Design and calculation of anti-slide piles – Engineering examples. Chapter 8: Cantilever retaining structures. Section 1: General introduction; Section 2: Theoretical basis for the design and calculation of cantilever retaining structures; Section 3: Sheet-pile type cantilever retaining structures; Section 4: Pile-row type cantilever retaining structures. Chapter 9: Design of bridge pile foundations. Section 1: Common forms of bridge foundations; Section 2: Calculation principles applicable to bridge pile foundations; Section 3: Analysis of pile foundations supporting frame-type bridge piers with relatively thin caps; Section 4: Torsional resistance calculations for symmetrically erected pile foundations; Section 5: Determination of single pile bearing capacity based on soil resistance; Section 6: Settlement calculations for pile foundations supporting bridge piers; Section 7: Design of bridge pile foundations in special ground conditions; Section 8: Example calculations related to bridge pile foundations; Section 9: Several issues needing attention during bridge foundation design; Section 10: Reliability assessment of skin friction acting on bored cast-in-place piles used in highway bridges. Chapter 10: Pile foundations utilized in coastal and offshore engineering. Section 1: General introduction; Section 2: Determination of vertical bearing capacity of pile foundations supporting port hydraulic structures; Section 3: Determination of vertical bearing capacity of pile foundations utilized in offshore engineering; Section 4: Horizontal behavior of piles; Section 5: Reliability analysis of pile foundations – Engineering examples. Chapter 11: Vertical bearing capacity of single piles. Section 1: General introduction; Section 2: Behavior of single piles under vertical loads; Section 3: End-bearing resistance and skin friction of piles; Section 4: Determination of single pile bearing capacity using standard code-based methods; Section 5: Determination of single pile bearing capacity via in-situ testing techniques; Section 6: Large-diameter cast-in-place piles; Section 7: Rock-socketed cast-in-place piles; Section 8: Steel pipe piles; Section 9: Recent engineering examples and latest research findings. Chapter 12: Vertical bearing capacity of pile groups. Section 1: Effects arising from pile group interactions; Section 2: Calculation of ultimate bearing capacity of pile groups. Chapter 13: Soil reaction forces acting on pile caps. Section 1: General introduction; Section 2: Relationship between soil reaction forces, piles, and soil deformation; Section 3: Characteristics of the distribution pattern of soil reaction forces; Section 4: Calculation of soil reaction forces and load-sharing values borne by pile caps. Chapter 14: Time-dependent effects influencing pile foundations. Section 1: Time-dependent effects affecting the bearing capacity of displacement piles installed in saturated cohesive soils; Section 2: Time-dependent variations in bearing capacity of displacement-type pile groups within saturated clay; Section 3: Time-dependent effects influencing the bearing capacity of non-displacement cast-in-place piles embedded in cohesive soils. Chapter 15: Settlement calculations. Section 1: General introduction; Section 2: Determination of relevant soil parameters; Section 3: Load transfer method; Section 4: Elastic theory approach; Section 5: Shear deformation transfer method; Section 6: Brief overview of other available methodologies. Chapter 16: Settlement calculations for pile groups. Section 1: General introduction; Section 2: Experimental studies concerning settlement characteristics of driven pile groups; Section 3: Experimental studies regarding settlement behavior of drilled pile groups; Section 4: Factors exerting influence over settlement patterns of pile groups; Section 5: Settlement of pile groups installed in non-cohesive soils; Section 6: Calculation of pile group settlement utilizing elastic theory approaches. Chapter 17: Horizontal bearing capacity and displacement responses of both single piles and pile groups. Section 1: General introduction; Section 2: Computational analysis involving short piles; Section 3: Computational analysis pertaining to long elastic piles; Section 4: Horizontal bearing capacity and corresponding displacement levels exhibited by pile groups; Section 5: Distribution patterns of stresses experienced by deeply embedded anti-slide piles. Chapter 18: Seismic checking procedures applied to pile foundations. Section 1: General introduction; Section 2: Scope of applicability wherein no seismic checking is necessary for pile foundations; Section 3: Seismic checking procedures applicable to low-cap pile foundations; Section 4: Behavior of pile foundations situated within liquefiable soils; Section 5: Structural requirements aimed at enhancing seismic resistance of pile foundations. Chapter 19: Construction practices involving precast concrete piles. Section 1: Pile splicing techniques; Section 2: Construction methodologies employed; Section 3: Necessary construction machinery and equipment; Section 4: Environmental impacts and corresponding mitigation strategies; Section 5: Accident prevention measures and remedial actions – Engineering examples. Chapter 20: Construction processes involving steel piles. Section 1: General introduction; Section 2: Required construction machinery; Section 3: Pile driving operations; Section 4: Quality control mechanisms; Section 5: Accident prevention measures and remedial actions. Chapter 21: Construction procedures applicable to cast-in-place piles. Section 1: Dry drilling techniques utilized for producing cast-in-place piles; Section 2: Drilling and pile formation processes supported by mud circulation, along with associated machinery and equipment; Section 3: Installation procedures for driven cast-in-place piles; Section 4: Engineering examples alongside recent technological advancements. Chapter 22: Underwater construction practices concerning pile foundations. Section 1: General introduction; Section 2: Preparatory steps required prior to commencement of work; Section 3: Pile driving via hammering techniques; Section 4: Installation of piles through static pressing techniques; Section 5: Supplementary underwater pile installation methods; Section 6: Construction procedures applicable to specialized types of piles underwater; Section 7: Common problems encountered during underwater pile foundation construction and their respective remedies. Chapter 23: Construction of pile foundations under unique environmental circumstances. Section 1: Construction procedures applicable to rock-socketed (or anchor-type) bored cast-in-place piles; Section 2: Application of bored/drilled cast-in-place pile technologies as a means of mitigating geological hazards; Section 3: Utilization of bored cast-in-place pile construction techniques for building underground diaphragm walls – Engineering examples. Chapter 24: Static load testing procedures applied to piles. Section 1: General introduction; Section 2: Axial compression load tests conducted on individual piles; Section 3: Horizontal loading experiments performed on single piles. Chapter 25: Quality inspection of piles and determination of vertical bearing capacity through dynamic testing methods. Section 1: General introduction; Section 2: Common quality-related issues likely to arise during pile foundation construction; Section 3: Inspection procedures assessing borehole quality; Section 4: Evaluation mechanisms aimed at ensuring overall pile quality; Section 5: Inspection activities conducted via excavation; Section 6: Core drilling techniques utilized for evaluation purposes; Section 7: High-strain dynamic testing methodology; Section 8: Discussion surrounding several key aspects of dynamic pile testing; Section 9: Latest developments witnessed within testing technologies alongside relevant engineering examples. Chapter 26: Prototype observation efforts directed toward pile foundation engineering. Section 1: General introduction; Section 2: Objectives pursued through prototype observation of pile foundations and associated instruments utilized; Section 3: Characteristics exhibited by pile foundations and corresponding monitoring mechanisms; Section 4: Engineering example featuring pile foundations supporting high-rise structures; Section 5: Concluding remarks. Appendix 1: Technical specifications governing construction of building pile foundations. Appendix 2: Guidelines applicable to low-strain dynamic testing of foundation piles. Appendix 3: Guidelines applicable to high-strain dynamic testing of foundation piles