Ibrahim Mashhour

Piles installed in collapsible soils experience negative skin friction that develops along the pile’s shaft, which reduces the pile capacity and increases its settlement. The negative skin friction is developed due to inundation of the ground and indirect loading (surcharge). A 3-D numerical model was developed using the finite element technique and the commercial software “PLAXIS 3D” to simulate the case of piles embedded in gypseous collapsible soil, overlying dense sand deposits. The objective of this investigation is to examine the developed negative skin friction for a given pile under the effecting of the loading, and soil condition after conducting pile load test. And accordingly, to determine the location of the neutral plane. In this investigation, the pile’s tip was located at the interface of the dense sand deposit, or at 5D higher or lower the interface. Piles were subjected to surcharge load of 50, 100, or 400 kPa and the axial load of 50–100% of the allowable axial load on the pile. The results were presented in the form of the changing (reduction) in the value of negative skin friction as well as the variation in the neutral plane location The maximum drag load reduction was recorded along the pile embedded in the dense sand layer with a depth equal to five times the pile diameter and subjected to a surcharge of 400 kPa under an axial load of 100% of the allowable load.

At the beginning of 2020, the COVID-19 contagious virus swept, which caused a lot of disturbances in all countries worldwide. The Egyptian government declared an emergency and placed the country under lockdown. Preventive measures such as social distancing, sterilization, mask wear, frequent temperature checks, offering COVID-19-related training, and encouraging work-from-home initiatives, among other precautions, have been implemented. Such precautionary measures affected the construction production rate. This research used a questionnaire and face-to-face interviews to solicit the opinion of construction industry professionals and experts on tier-one construction companies on the impact of this pandemic on construction production rate. A quantitative analysis has been done in this study using IBM SPSS Statistics 26© to determine the most important effective factors of the production rate of the construction industry, mainly in Egypt. Also, this study illustrates an Artificial Neural Networks (ANNs) model to predict the project’s cost and production rate at construction for the actual status in Egypt at the peak of COVID-19. The model does not only present the actual case but can also predict the most important and influential factors of the construction industry mainly in Egypt, at the peak of the virus, and can be used in other similar crises as a lesson learned which no study covered this area at the previous works. Finally, the results and the validation study of the proposed ANN model in the research show and present the actual status of production rate in the construction sector, mainly in Egypt (case study), and also predict the production rates of the construction sector at the future crisis.

The construction costs of hospital buildings are relatively high due to the need to fulfill their complex functions and avoid mishaps. In this context, this study aims to minimize the total construction costs of hospitals while still satisfying the special architectural, practical, and structural requirements specified by design codes. To this end, 48 design alternatives with two floor systems (flat slabs with and without drop panels), three column spacings, and eight concrete grades were optimized using genetic algorithms provided by Palisade Evolver. The objective function included the materials and labor costs per square meter of the floor plan. The decision variables involved the concrete dimensions and steel bars of floors and columns. The hospital buildings were subjected to gravity, earthquake, and wind loads to thoroughly examine the realistic loading conditions. The design was performed in accordance with the Egyptian code for the design and construction of concrete structures and the Egyptian guidelines for hospitals and healthcare facilities. The results revealed that using low-strength concrete, and flat slabs without drop panels could achieve the best design. The slab thickness had a governing impact on the total cost of both floor systems.

Compacted clays are commonly utilized as landfill liners due to their impermeable properties, however, the availability of natural clay soil may be difficult or prohibitively expensive in some regions thanks to the expense of transportation, the local soil availability or regulation. As an alternative hydraulic barrier, a compacted mixture of sand with a low percentage of bentonite (6% to 14%) was used. The purpose of this research is to investigate the applicability of bentonite available in the Egyptian market for controlling the hydraulic conductivity of sand-bentonite mixtures to be used in landfill liners. The study was divided into two phases: first, laboratory tests were conducted to identify the optimum bentonite percentage and bentonite types, using local commercial bentonite products. Then, in two distinct landfill liners layers, full-scale measurements were obtained. The experimental program demonstrated that Bentonite produced and found in the Egyptian market can be utilized in landfill liners with an acceptable quality control procedure to prevent any outcome deviation.

Collapsible soils possess a considerable strength when dry, and experience a significant and sudden loss in its strength and excessive settlement upon wetting. In the field, wetting may take place due to the rise of the groundwater level or flooding on the ground surface. End-bearing piles are widely used to penetrate these collapsible layers, in order to transfer the building load to a stronger deeper soil layer. While in the literature, reports can be found dealing with evaluating the interaction between piles and collapsible soil when fully inundated (full saturation), the research on the behavior of this soil when partially saturated is lagging behind. This is due to the complexity of modeling and the lack of field data. This paper presents the results of experimental modeling of an end-bearing pile penetrating collapsible soil subjected to partial inundation due to surface running water. The objective is to determine the drag load acting on the pile’s shaft when the degree of saturation increases along the collapsible soil layer surrounding the pile shaft. The measured drag load is presented as function of the degree of saturation, the collapse potential of the soil layer and pressure acting on the soil.