Observational Method for the Design of a New Ground Improvement Concept Adapted to a Large-Scale Fast-Track Project

In 2007, the King of Saudi Arabia launched a large scale development program for the construction of a complete university campus on an existing lagoon. The fast-track project was to be completed within a period of 24 months leaving no time for the usual preliminary investigation and design phase. The 5,600,000 m2 site was selected north of Jeddah and a proper soil inves-tigation could not be completed ahead of the start of construction due to difficult site access and challenging existing soft soil condition. In addition to that, because the structural design or even the master plan had not been finalized, the design of the foundation system (loads, footing location...) was going to be completed concurrent with the construction itself. A new con-cept of foundation support, based on ground improvement, adapted to all potential ground conditions and allowing structures to be randomly located had to be designed and built in record time. The further challenge was to establish the soil parameters and improvement methods. To fit into the extremely tight schedule of the job, the observational method ended up being the best way to define reliable and tested parameters for the ground improvement design and selection to adapt to constantly changing conditions. Late changes in the type of structures combined with difficult site working conditions presented the team with challenges that lead to an innovative use of an optimized combination of Dynamic Compaction, Dynamic Replacement, High Energy Dynamic Replacement and Dynamic Surcharging to meet both the schedule deadlines and the improvement cri-teria

A Case of Vibro Compaction Vibration Monitoring in a Reclaimed Site

Vibro Compaction is a ground improvement technique in which the soil is compacted using waves generated from an equipment called a vibroflot. As the vibration magnitude is less than some other vibratory ground improvement methods this technique is sometimes preferred when the improvement zone is relatively close to existing structures and facilities. Unfortunately, not much can be found in literature on peak particle velocity (PPV) that is generated by this method. This paper reports and interprets vibration monitoring of a Vibro Compaction project that was recently performed on about 13 m of hydraulically placed sand in Palm Jumeira, Dubai. PPV was measured at different distances from the vibroflot. The depth of the vibroflot was also varied to provide a better understanding of the critical depth that creates the largest PPV. A formula is also presented to estimate Vibro Compaction generated PPV during planning stage

Methodology of the direct C–H bond functionalization in nitrogen-containing heterocycles

Предложены два эффективных методологических подхода для проведения прямой функционализациии связи С(sp2)–H в альдонитронах. Палладий(II)-катализироуемое окислительное С–С сочетание с индолами и пирролами приводит к нитронам, содержащим N-оксидную функцию. Продуктами некатализируемого переходными металлами нуклеофильного замещения водорода (SNH) являются дезоксигенированные имидазолы.Two effective methodological approaches to the direct С(sp2)–H bond functionalization in aldonitrones have been proposed. Palladium(II)-catalyzed С–С coupling with indoles and pyrroles results in the nitrones bearing N-oxide function. The products of the uncatalyzed by transition metal nucleophilic substitution of hydrogen (SNH) are the deoxygenated imidazoles.Программа развития УрФУ на 2013 год (п.2.1.2.1

Application of Dynamic Replacement in a Steel Pipe Factory

Prior to the construction of Al Jazira Steel Pipe Factory (AJSPF), almost all buildings in the Industrial City of Abu Dhabi were constructed on piles. This was due to the presence of compressible layers of soil, especially a superficial layer composed of one to four metres of soft sandy silts and clays. To the knowledge of the authors AJSPF is the first project in this area that has been built without the implementation of any piles and founded on shallow foundations improved by Dynamic Replacement. Variations of loading conditions and design criteria has made this pioneer project of special interest. While classical Dynamic Replacement was used for some ground slabs, pre-excavated Dynamic Replacement was applied under single footings and heavily loaded storage areas. As a cost saving method, sand from local Abu Dhabi excavations was used as granular material in lieu of the more commonly used crushed stone. Pressuremeter Tests (PMT) and finite element analysis was able to demonstrate that acceptance was achieved

Application of Dynamic Surcharging for Construction of Tanks on Reclaimed Ground

Palm Jumeira is a reclaimed island off the coast of Dubai. While almost all heavy structures built on this island have been piled, the heaviest non-piled structures that have been constructed are two sewage treatment tanks that have used a unique and innovative Dynamic Surcharging ground improvement solution for their foundation systems. For each tank, a 4 m high surcharge was initially placed on the tank’s area and left in place for several days. Then dynamic surcharging was performed by dropping the pounder at the periphery of the surcharge embankment to induce additional settlements. The surcharge was then removed, the ground level reduced, print locations additionally excavated, and dynamic compaction was carried out. Post ground improvement Menard Pressuremeter Tests (PMT) and finite element calculations demonstrated that acceptance criteria were achieved

Application of Dynamic Compaction in Reclaimed Roads

Pavement layers are systematically constructed as engineered fills with specified properties and criteria; however these well built layers may be underlain by loose saturated subgrades that, if not treated, may be subject to undesirable and damaging deformations. This may be especially true for roads that are constructed on reclaimed land. Dynamic Compaction is a ground improvement technique that can and has been effectively utilised for treating thick loose layers of saturated in situ or reclaimed granular soils. In this paper, the application of Dynamic Compaction for improving loose sub-grades will be discussed using three case studies. The case studies have been specifically selected in a manner to demonstrate the applicability of this technique to hydraulic fills and truck dumped fills, to very large projects such as the 900,000 m2 Abu Dhabi Corniche, to moderately large projects such as Marjan Island Main Road corridor and to relatively small sized projects such as the 10,000 m2 approach roads of Reem Island Causeway. The projects can be in undeveloped locations or in urban areas

Predicting Menard Modulus using Dynamic Compaction Induced Subsidence

Previous research by Varaksin et al. suggests that it is possible to develop a relation between strain and increase in Menard Pressuremeter (PMT) limit pressure, whereas limit pressure will double every time the ground is strained strain 3%. Later, Hamidi et al. proposed a new method to predict the limit pressure profile after dynamic compaction with the assumption that induced ground subsidence is the accumulation of vertical strains according to a Rayleigh distribution. Comparison of the geometric mean of predicted and post improvement measured limit pressure values suggest that this method of calculation is quite reliable. Noting that there are also established empirical relationships between the limit pressure and Menard Modulus, it would seem rational that a similar method can be used to predict the Menard modulus. This has been studied in this paper and it can be observed that for practical purposes, this method is able to provide Menard Modulus values of the correct magnitude

The Application of Dynamic Compaction on Marjan Island

Marjan Island is 2.7 million m2 of development located 27 km southwest of Ras Al Khaimah in the United Arab Emirates. This project has been reclaimed from the Persian Gulf by tipping sand into the sea. Geotechnical investigations indicated that the upper 7 m of ground was composed of very loose to medium dense silty sand interbedded with layers of boulders at different depths. SPT blow counts were recorded to be as low as 4 and Menard Pressuremeter Test (PMT) limit pressure was as low as 70 kPa. Fines content was from 13 to 30%. Preliminary calculations suggested that the in-situ ground conditions could not satisfy the island’s main road’s settlement criteria and that ground improvement was required. Thus, 198,000 m2 of the reclamation was treatment by Dynamic Compaction. Pounders weighing up to 20 tons were dropped from 20 m to compact the loose soil. 32 PMT were carried out after ground improvement to verify the achievements. These tests were able to demonstrate that acceptance criteria was readily achieved and that on average the soil’s modulus of deformation increased by more than 400%