China
Africa
Explore chapters and articles related to this topic
Settlement estimations for buildings founded on saturated silty sands from CPT and DMT results
Published in Guido Gottardi, Laura Tonni, Cone Penetration Testing 2022, 2022
Maxwell Cáceres, Javier Fumeron, Felipe A. Villalobos, Ricardo Moffat
Bearing capacity and settlements are key components in the analysis and design of foundations. Bearing capacity of shallow foundations is usually calculated adopting the Terzaghi procedure which has been extended for different conditions (geometry, loading). However, in silty sands the design becomes controlled in most of the cases by the allowable settlement and not by bearing capacity. Therefore, estimations of settlements are crucial in almost every project. Settlement estimation involves usually the determination of the soil stiffness by means of an operational deformation modulus related to the design load range, which can be obtained from laboratory tests such as triaxial tests. Alternatively, in situ tests can be carried out instead or to complement the information from laboratory. In situ testing can have benefits in terms of measuring directly in the soil without the hassles of extracting, transporting, storing and the preparation of samples. A traditional in situ test carried out in projects is the standard penetration test SPT. However, there are concerns about its reliability and result interpretation for soil stiffness due to poor reproducibility and lack of continuity (Robertson, 2012). In situ load plate test can provide a scaled footing load-displacement response. However, its applicability is limited to surface or shallow depths.
Dynamic Bearing Capacity of Shallow Foundations
Published in Swami Saran, Dynamics of Soils and Their Engineering Applications, 2021
The strength of the soil notably reduces when subjected to seismic excitation, because of the extensive inertial stresses induced during shaking. The decrease in strength of soil leads to a significant reduction in bearing capacity of footing; while increase in the settlement. This reduced bearing capacity is termed as seismic bearing capacity of footing and the increased settlement is called seismic settlement.
Bearing capacity of foundations
Published in Buddhima Indraratna, Ana Heitor, Jayan S. Vinod, Geotechnical Problems and Solutions, 2020
Buddhima Indraratna, Ana Heitor, Jayan S. Vinod
Foundations are part of civil infrastructure that facilitate transfer of both static and dynamic loads from the superstructure safely to the underlying ground. Shallow foundations are considered when geological material at the ground surface has ample strength to withstand this applied load. Deep foundations are usually required when the soil below the structure has a relatively poor load-bearing capacity; thus, the loads must then be carried to deeper soil layers using piles (driven or bored), granular columns or caissons. In general, the bearing capacity can be defined as the largest intensity of applied pressure by a structural member to the soil, which supports it without causing excessive settlement or shear failure. In view of design, the ultimate and allowable bearing capacities play an important role.
Assessment of bearing capacity and failure mechanism of single and interfering strip footings on sloping ground
Published in International Journal of Geotechnical Engineering, 2021
Bearing capacity (qu) of footing defines the maximum load that the foundation can carry without failure within allowable limits of settlement. The load-carrying capacity of foundation depends on geotechnical and geometrical characteristics. Geotechnical characteristics comprise the shear strength and deformation parameters of soil. Geometrical characteristics include the size, depth and shape of the footing. To design an adequate foundation for superstructures, bearing capacity is the key for geotechnical engineers. In this regard, based on several assumptions, Terzaghi (1943) had provided the first expressions to assess the bearing capacity of a strip footing resting over a semi-infinite horizontal ground surface. Meyerhof (1951) further extended the proposition by assuming that the developed failure surface in the passive zone extends up to the ground surface, thus providing a different set of bearing capacity factors (Nc, Nq and Nγ). Later, based on theory, field and laboratory investigations, Skempton (1951) provided modified expressions for Nc considering footings of different shapes, sizes and embedment depths within a saturated clay medium. Thereafter, based on the work of several researchers (Hansen 1970; Vesic 1973), a general bearing capacity expression had been formulated, including all possible contributions of shape, size, embedment depth, load inclination and compressibility of the founding medium.
Finite element and ANN-based prediction of bearing capacity of square footing resting on the crest of c-φ soil slope
Published in International Journal of Geotechnical Engineering, 2020
Rana Acharyya, Arindam Dey, Bimlesh Kumar
Bearing capacity of foundations is one of the prime concerns for geotechnical engineers as it aids in its assessment and design. Design of foundations on a horizontal ground surface depends on the mechanical characteristics of the soil (unit weight and shear strength parameters) and the physical properties of the foundation (depth, width and shape of the footing). There are two primary considerations to decide the allowable bearing pressures of shallow foundations: (a) the safety factor against ultimate shear failure must be adequate, and (b) the settlements should not exceed the acceptable limits. Conventionally, the ultimate bearing capacity of foundation is defined as the maximum stress that it can carry without undergoing a shear failure. Based on the shear strength parameters of the soil, Terzaghi (1943) was the first to quantify the ultimate bearing capacity of a strip footing resting on a uniform horizontal ground, which is used extensively even today. The basic proposition for the bearing capacity of strip footings has undergone several modifications, primarily related to the theoretical bearing capacity factors, as well as inclusion of several new contributory factors (Meyerhof 1951; Hansen 1970; Vesic 1973). However, strip footings are not commonly used as building foundations, except for the load bearing walls. Hence, in order to accommodate different shapes of the footings (square, rectangular, circular or combined), shape factors were introduced in the bearing capacity expressions (Hansen 1970; Vesic 1973).
Laboratory testing and numerical modelling on bearing capacity of geotextile-reinforced granular soils
Published in International Journal of Geotechnical Engineering, 2018
Vahid Rashidian, Seyyed Abolhasan Naeini, Meisam Mirzakhanlari
Inadequate bearing capacity of weak soils can be improved by implementing the geosynthetic reinforcing technique. In this research, the effects of placing geotextile reinforcement layer(s) on bearing capacity of two granular soils with different fine contents were investigated. The standard CBR tests were performed in laboratory on the unreinforced soil samples as well as reinforced with one, two or three nonwoven geotextile layer(s). It was found that for the soil with lower fine grains content, the geotextile efficiency in increasing the bearing capacity is lower in compare to the soil with higher fine content. It was also observed that increasing the number of geotextile layers in both soils specimens will not necessarily increase the bearing capacity and even might decrease it in compare to the samples with fewer geotextile layer(s).