Abstract:
The estimation of bearing capacity for shallow foundations in swelling soil is an important and complex context. The complexity is due to the unsaturated swelling soil related to the drying and humidification environment. Hence, a serious study is needed to evaluate the effect of swelling potential soil on the foundation bearing capacity. The purpose of this paper is to analyze the bearing capacity of a rough square foundation founded on a homogeneous swelling soil mass, subjected to vertical loads. A proposed numerical model based on the simulation of the swelling pressure in the initial state, followed by an elastoplastic behavior model may be used to calculate the foundation bearing capacity. The analyses were carried out using the finite-difference software (FLAC 3 D) with an elastic perfectly plastic Mohr–Coulomb constitutive model. Moreover, the numerical results obtained are compared with the analytical solutions proposed in the literature.
The numerical results were in good agreement with the analytical solutions proposed in the literature. Also, reasonable capacity and performance of the proposed numerical model.
The proposed numerical model is capable to predict the bearing capacity of the homogeneous swelling soil mass loaded by a
shallow foundation. Also, it will be of great use for geotechnical engineers and researchers in the field.

Keywords : Bearing capacity, Numerical approach, Rough interface, Square footing, Swelling pressure

Abstract: The design of shallow foundations on swelling
soils needs a thorough study to evaluate the effect of
swelling potential soil on the final foundation heave. For
this reason, a simple analytical approach based on the soil
stress state under the foundation can be used to calculate
the foundation heave. This paper reports a set of analytical
and numerical analysis using the finite-difference code
(FLAC 3D), performed on an isolated shallow foundation
founded on a swelling soil mass at N’Gaous city in Batna
Province, Algeria, subjected to distributed vertical loads.
Further, the influence of some parameters on total heave
was analyzed, such as the embedded foundation and
soil stiffness. The analysis results from the proposed
3D modelling was compared and discussed with
analytical results. The numerical results obtained show
a good agreement with the analytical solutions based on
oedometer tests proposed in the literature, and deliver
a satisfactory prediction of the heave of the shallow
foundations.

This paper presents an experimental study to evaluate the effect of local mineral additions (pozzolan, slag and limestone) on the rheological behaviour of based cement binder’s pastes. The binary, ternary and quaternary binder pastes were prepared with the partial clinker cement replacement limited up to 20%, according with type CEM II specifications. The cements were characterized by their geometric shapes, the reactivity and the chemical composition. An experimental design plan was used to modelling the rheological behaviour of pastes. The relatives yield stress and plastic viscosity of binder’s pastes, with normal consistency, were determined. The results showed that all the tested compositions with additions follow the same rheological behaviour law according to the Bingham model. The binder pastes rheological parameters (yield stress and viscosity) are affected by mineral additions. The highest values of the rheological parameters were measured in binary and ternary cements with limestone and pozzolan. On the other hand, the lower viscosity among the tested pastes was obtained with slag addition. The statistical approach allowed us to obtain a satisfactory modelling of viscosity and yield stress with a coefficient of determination R2 = 0.91 and 0.92, respectively and a satisfactory correlation between the viscosity and the water/binder ratio (W/B) for a normal consistency with a coefficient of determination R2 = 0.91. Keywords: Blended cement, mineral additions, rheological behaviour, viscosity, yield stress

This paper presents an experimental study aimed at evaluating the reactivity of natural and industrial local mineral additions (pozzolan, slag and limestone) by different microstructural and mechanical approaches. Binary, ternary and quaternary cement compositions were prepared with partial replacement of the clinker by additions limited to 20%, according to CEM II / A cement specifications. The reactivity during the hydration process is characterized by the hydraulic power of the additions to react with the water and the hydrates of the cement and the pozzolanic capability of fixing the portlandite to form new mineral phases which contribute to the resistance as much as the hydrated products of cement. An experimental methodology was established for the reactivity illustration of the additions by a microstructural approach based on a study of the physicochemical and microstructural properties realized by X-ray diffraction (XRD), the scanning electron microscopy (SEM) on pastes. Further, thermogravimetric analysis (TGA), mercury microporosity (MIP) on mortars at 28 days of age was performed. A mechanical approach based on compressive strength at 2, 7 and 28 days to determine the activity index according to ASTM C 618 has been undertaken. The results obtained show a good correlation between the microporosity, X-ray diffraction and the resistance activity index, in particular for the slag, as for the thermogravimetric analysis that clearly confirms the pozzolanic activity of the pozzolan addition.

The construction industry is a major sector in the economy of developing countries. During the last two decades in Algeria, many large-scale construction projects have been launched to develop the basic infrastructure facilities of the country. However, most of these projects experience extensive delays. The objective of this paper is to identify the causes of delay in the Algerian construction industry and assess their importance according to the main project stakeholders, which are the owner, the contractor and the consultant. Data were collected through a questionnaire and direct interviews of a sample of construction experts including 16 owners, 16 contractors and 20 consultants. Fifty-nine causes of delay were identified in this research. The results indicate that the five most important causes are slow change orders, unrealistic contract duration, slow variation orders in extra quantities, delays in payment of performed work and ineffective planning and scheduling by contractors. The study revealed that owner-related causes are the most important sources of delay. The findings of this research can be used to guide the improvements of the construction industry in Algeria.

Stability of slurry trenches is an important issue during the construction of groundwater cutoff and diaphragm walls and, thus, has gradually drawn additional attention. With the aim of controlling the stability and collapse mechanism of slurry walls better, an analytical approach based on interactions between horizontal and vertical arching effects was conducted to estimate the stability factors for general and local stability of a slurry-supported trench panel in cohesionless soils. The results show that arching has certain characteristics that affect soil behavior near the trench, including directions of loading and unloading of soil, variation of active pressure coefficient on the sidewall interface, and a created downward load transfer mechanism. The trench stability depends on two types of safety factors; the first factor prevents sliding collapse (overall stability), and the second factor prevents collapse of the soil interface (local stability) because local interface instability triggers overall trench collapse in cohesionless soil. The solution was compared with field measurements and three-dimensional (3D) finite-element analyses (with the effect of the third dimension), which permitted study of the influence of the arch located in the third direction. The satisfactory correspondence validates this approach and shows that the 3D analytical analysis perfectly describes the phenomenon.

The shrinkage and swelling phenomena of certain clay soils cause differential settlement manifested by disorders that affect mainly the individual frame. The objective of this research was to create a map related to these phenomena especially in the area of Algeria N’gaous (figure 1). The approach of the study is primarily based firstly on the interpretation of a geological map at a scale 1 : 50 000 and on the other part from existing literature and observations on a synthesis of a large number of geotechnical information to determine susceptibility to the phenomenon of clay or marl formations. This approach consisted in the establishment of a synthetic departmental mapping of these formations that have been identified from a hierarchy as to their susceptibility according to the shrinkage and swelling phenomenon. This classification was established on the basis of three quantifiable main features: the dominant lithology of formations, the mineralogical composition of their clay fraction (proportion of swelling minerals) and geotechnical behavior (primarily assessed from the blue value and the plasticity index). Key words: marl, smectite, shrinkage and swelling, natural risk, geotechnical mapping,

Swelling soils can be found in many parts of the world. The state of practice in this area has been changing over recent decades. The design of foundations for expansive soils is an impo rtant challenge facing engineers. The excessive damage is, in part, due to the lack of proper design, resulting in the need for better tools for practitioners in order to assess the impact of swelling soils in typical design applications. A correct measurement of the swelling pressure is required for an accurate prediction of the heave. A theoretical model is proposed to describe the swelling potential of clay soils on the basis of their characteristics obtained from oedometer tests. This paper describes analysis of the behavior of swelling soils when moistened under buildings and structures. The methods and principles currently used for the design of structure foundations on swelling soils involve important problems due to the non-uniform deformations of these soils when subjected to structural loads. The current study was conducted to compute the uplifting of shallow foundations on swelling soils considering the water-content change as well as the contact-pressure distribution under the footing.

Swelling soils are found in many regions throughout the word. The state of the practice in this area has been changing over the past decades. Design of foundations for expansive soils is an important challenge faced by engineers. The methods and principles currently used for the design of foundations on swelling soils involve important problems due to non-uniform deformations of these soils when subjected to structural loads. In situ and laboratory tests were used to investigate the most fundamental aspects. This article analyses the behaviour of a pile in a swelling soil when it is moistened. The tendency that develops at the present time, for the design of a pile in a swelling soil, consists in verifying the calculation of the bearing capacity of piles, taking into account the reduction of the resistance induced by the swelling soil on the lateral surface of the piles. This situation leads to an upward displacement of the pile, and, in case of excessive humidity the characteristic of the rigidity as well as the bearing capacity charge, which in this case decreases. An analytical approach of introducing a contribution, proposed method consists in calculating the rise of the pile, based on the study of the influence of a swelling clay type and the length of the pile. Keyworsd: Swelling Soil, Piles, Uplift, Tension.

This paper analyses the behavior of swelling soils when they are moistened under buildings and structures. The methods and principles used currently for the design of structure foundations on swelling soils involve important problems due to non uniform deformations of these soils when subjected to the structure loads. In order to avoid the negative effects of swelling soils and to reach the desired performance on one hand, and the economical results on the other hand, the special computations of the foundations stiffness and deformability must take into consideration the prevention of the swelling soils feature and in some cases preserve it. The current study was conducted in order to design flexible continuous footings on swelling soils taking into account the water content change on one hand and the contact pressure distribution on the footing on the other hand. Keywords: clay, swelling, swelling magnitude, swelling pressure, continuous foundation.