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By Federico Pagliacci, Claudio Asioli, Marco Chiarabelli

"""Rigid inclusions"" are a consolidation method that provides improvement of soft soils thanks to the installation of cylindrical columns made up of a material with significant and permanent cohesive properties, whose stiffness is 500÷5000 times greater than the surrounding natural soil’s. ""Rigid inclusions"" find their application in marginal areas (reclamations, polluted sites) to ensure stability of adjacent structures during construction of new buildings and to reduce the impact of natural disasters (liquefaction in the event of earthquakes, embankment collapse in the event of floods). This paper analyses the “rigid inclusion” construction method, related materials and equipment. Moreover, two performed projects will be illustrated. The first is the restoration of Lungarno Torrigiani Embankment in Florence, Italy. In May 2016, the Torrigiani embankment underwent a structural collapse causing a 3 m. displacement of the riverbank towards the Arno River. “Rigid inclusions” (with 300 mm diameter) have been used to re-compact the loose soil and create a stable working platform for the equipment. The second project illustrates the use of “rigid inclusions” (800 mm diameter and maximum depth of 36.6 m) to control the settlement of a new automatic cold store (30 m high with a 65 x 120 m foot print) for fresh frozen vegetables.RIGID INCLUSIONSIn general, the word ""inclusions"" means a type of consolidation that improves the strength of a soil mass through the inclusion of elements constituted by a material having better characteristics than those of the surrounding natural ground, to improve the overall mechanical characteristics of the treated soil. Inclusions are ""rigid"" when the material introduced into the ground has significant and permanent cohesive properties (concrete or cement mortar) and a significantly higher stiffness (500 ÷ 5000 times) than that of the surrounding natural ground.Typically, medium-small diameters (from 300 to 800mm) with low percentages of treatment (from 2% to 10% of the volume of soil) are employed, ensuring a high quality and consistency of the obtained product, both in terms of diameters and elastic modulus.According to the scope of the project and in urban areas, ""rigid inclusion"" columns can also be performed by means of small diameter drilling rigs (micropiles), weighing less than 20-25 tonnes."

Jan 1, 2017

By Barritt Lovelace

Collins Engineers has been researching and implementing the use of drones on Civil Engineering Projects since 2015. Applications include bridge inspection, asset management, mapping, construction site management and emergency response. Recently this technology was used to map and model construction sites with deep foundations to verify and quantify designs. The ability to collect and use large amounts of data is transforming our world. Drone hardware and software is being used to capture and digitally replicate assets, giving owners unprecedented ability to visualize and manage their projects. Our teams help owners collect and process drone data into deliverables to be analyzed, annotated, stored, and shared. The use of drones can transform the way projects are managed and can improve project workflows. Data collected with drones can be processed into a digital twin of any project site or asset. This digital twin provides owners with a three-dimensional geometrically and geospatially accurate model. These models can be annotated and tagged with information that can be stored and shared locally or on cloud-based platforms. The data can be exported and used in a wide variety of CAD and GIS platforms. Goals When considering the use of UAS for several items need to be considered when establishing project goals. Safety Drones can be used to reduce job site safety risks in two ways. The first is that use of the drone can remove personnel from harm’s way. Surveyors and other project staff will traditionally walk the site to collect survey and other site information. These efforts can be replaced with the use of a drone eliminating much of the need for personnel to be on the job site itself which improves safety. The other way safety can be improved is that a digital model of a job site can be created on a daily or weekly basis that can be quickly analyzed for safety hazards. This analysis could be done remotely by safety officers to identify job site hazards which can then be corrected before injuries happen. Improved Deliverables Perhaps the most important reason to incorporate drones into project workflows it the ability to improve the project deliverables. Drones have the ability to quickly collect large amounts of high quality data which can be processed into orthomosaics, point clouds and 3D models that give engineers and project managers the information they need to make better decisions on design or project management.

Jan 1, 2019

By Patrick K. Wong, Richard Kelly

"The variability in strength and compressibility of in situ deep soil mixing products can be greater than the variability of the natural soil. However, satisfactory performance can be achieved by careful construction and an appropriate QA/QC program. This paper presents a case study on the use of deep dry soil mixing columns to support several embankments over soft clay along a highway project. Post-construction settlement monitoring indicated that good performance is achieved where the acceptance criteria are met, except in an area with high organic content. Embankments with contrasting performance are compared to the quality control test results which comprised laboratory testing of core samples as well as in situ test results such as pull-out and push-in vanes and conventional cone penetration tests. Drawing on the performance results and quality control testing, discussions and guidelines are given on quality assurance acceptance criteria and construction control testing regime for future projects.INTRODUCTIONBetween 2008 and 2012, the largest deep dry soil mixing (DSM) contract during that time in the southern hemisphere was carried out for the Ballina Bypass project. The project, comprising 12 km upgrade of the Pacific Highway located in northern New South Wales close to the border of Queensland, was commissioned by the Roads and Maritime Services (RMS) of NSW. The ground improvement contractor was Keller Ground Engineering (KGE) Australia. Seven different types of ground improvement techniques were employed for the project, ranging from low embankment strategy with nominal preloading, to surcharge with wick drains, light weight bottom ash fill, DSM, vibro-replacement stone columns, dynamic replacement, and vacuum consolidation (installed by Menard Bachy Pty Ltd). Different techniques were chosen depending on time program, cost, and performance requirements relative to proximity to piled structures (e.g. bridge abutments) and post-construction settlement and differential settlement for either rigid or flexible pavements at different locations.DSM was the most utilized ground improvement technique employed on the project, comprising a total of about 285 km of 0.8 m diameter columns to depths up to 18 m for the purpose of supporting bridge approach embankments and culverts with embankment heights up to 6 m. DSM was chosen due to the very soft nature of the clay soil with moisture content practically at liquid limit, and the relative speed and economy of the system. Dry cement powder at rates of 160 kg/m3 to 200 kg/m3 were pneumatically discharged via the hollow stem of the mixing tool, and mixed with the soil (using multiple horizontally mounted paddles on a single vertical stem) at high speed as the mixing tool is withdrawn."

Jan 1, 2015

By Craig M. Shillaber, Joseph E. Dove, James K. Mitchell

"This paper addresses two primary factors affecting the sustainability of Deep Mixing Methods (DMMs): construction materials and handling of the spoil from wet mixing methods. We examine these factors within a life-cycle embodied energy (EE) and carbon dioxide (CO2) emissions accounting framework, using the LPV 111 project in New Orleans, LA as a case history. The underlying assumption is that project planning and preliminary design have determined that a DMM is the best ground improvement alternative for achieving the broader aims of sustainable development. While EE and CO2 emissions are direct measurements of environmental impact alone, we illustrate how their minimization can also influence the social and economic consequences of the project. It is recommended that DMMs use lower energy and carbon material alternatives to Portland cement and lime in the binder whenever possible, with preference given to locally sourced materials. Currently available alternative cementitious materials include fly ash and slag, which are waste products from other processes. In addition, recycling the spoil material from wet mix methods on site is recommended. If the material cannot be recycled on site, transporting it to a processing and recycling center for later use as fill is preferred over landfilling. INTRODUCTIONWithin the geotechnical community there is an increased appreciation for sustainability considerations, which are an important component of the planning, design, construction, operation and maintenance of projects. An assessment of project sustainability includes holistic life cycle thinking, systems analysis, environmental impact assessment, use of safe and benign materials, awareness of local societies and cultures, social equity, protecting human health and well-being, and monetary costs (Abraham, 2006). Since ground improvement is a principal practice domain of geotechnical engineers, it is important that geo-professionals play a role in addressing the sustainability for these projects. In this paper, we illustrate by case history how different materials and methods associated with deep mixing projects can impact overall project sustainability through quantifying project embodied energy (EE) and carbon dioxide (CO2) emissions. EE is defined as all energy consumed to bring something into its present state (Chau et al., 2008; Inui et al., 2011; Soga et al., 2011; Chau et al., 2012). Recommendations are then made for how adverse environmental impacts of Deep Mixing Methods (DMMs) may be minimized, leading to more sustainable geotechnical construction."

Jan 1, 2015

By Stuart Coutts

"This paper presents an overview of the author’s experience related to the assessment of the base capacity of straight shafted and enlarged-base bored piles in sand. A design approach based on CPT qc is described which has been calibrated using a database of load tests. The importance of correct installation techniques with instrumentation are illustrated and a discussion is presented on the current use of high strain dynamic testing to validate compliance with design. An example of a recent project with high quality instrumented load test data illustrates the close match to the proposed best practice approach and also highlights the importance for consideration of the effects of stress relief for deep foundations installed in deep excavations.1 INTRODUCTIONContinuous Flight Auger (CFA) piles are the bored foundation pile of choice for sand deposits across Australia. The evolution of the determination of the base resistance of CFA piles has been shaped by available investigative techniques, calculation methods, and calibration of designs with laboratory and field testing. The Cone Penetration Test (CPT) has been widely used in Western Australia (WA) where the test has been commercially available via multiple contractors for more than 25 years. On the East coast, the adoption of CPT testing has been slower with a transition from traditional Standard Penetration Testing (SPT) still occurring. Dynamic pile load tests are often used to derive parameters. The influence of pile installation on performance is commonly misunderstood and is an important element on any discussion of pile capacity for CFA pile types. The interface between the base of the constructed pile and the in-situ soil has an influence on capacity such that a poorly constructed pile base will have limited (if any) contribution to pile performance within the normal working range, generally within a 10 mm movement. The research presented in this paper pertains to CFA piles (no drilling fluids) and enlarged base piles constructed using CFA techniques under drilling fluids such that clean pile/base interface is targeted. Developments in modern piling equipment and instrumentation allow the pressure and volume of delivered concrete/grout to piles to be accurately monitored at various stages of installation such that repeatable ‘best practice’ can be achieved. The changes in soil conditions that occur due to the disturbance of the install technique are also important.Although the results of this research are likely applicable to bored piles, the interface between the pile and in-situ soil (shaft and base) need to be considered for various installation techniques. The effects of stress relaxation (due to removal of soil above pile base and adjacent shaft), time to concreting, and the zone of disturbed soil around the pile shaft are paramount.2 INSTALLATION CONSIDERATIONS The pile mix (concrete/grout) and interface with the in-situ soil are also an important consideration. For example, coarse grained, poorly graded, dry, clean sand will be partially permeated by most pile mixes; such that the influenced soil will be enhanced and in instances the overall effective pile dimensions increased. Permeation of the disturbed zone of a pile or anchor shaft along with scale effects (Lehane 2009) can have significant effect on shaft capacity and shaft frictions significantly exceeding expected are not uncommon based on ‘theoretical’ dimensions. Advancements in mix technology and mix techniques also have a large influence on the pile/soil interface. The ability of the piling rig and augers to excavate a plumb and gauge hole can also have a large influence on the zone of soil disturbed adjacent the constructed pile with a resulting influence on capacity."

Jan 1, 1900

By M. Hesham El Naggar, Mehdi Heidari

"Equivalent fixed-base cantilever model is a common approach for performance base seismic design of bridge structures supported by extended pile-shaft. In this method, global displacement ductility factor is related to local curvature ductility demand by assuming a concentrated plastic hinge at location of maximum bending moment. Equivalent plastic hinge length is one of the key parameters that should be assumed accurately in kinematic expression of the cantilever model. Although, some expressions have proposed to estimate the length of the in-ground plastic hinge; however, these relations yield differing results. In this paper, a general expression is derived based on the concept of distributed plasticity to predict the plastic region of yielded piles in clay and sand. A length modification factor is defined to relate the equivalent length of plastic hinge to the real plastic zone. Then, results from nonlinear pushover analyses are used to propose an equation for the modification factor as a function of displacement ductility factor.IntroductionDuring severe earthquake events, development of the plastic hinge in pile foundation below ground level is inevitable for bridge structures supported on extended pile-shafts. A common approach for seismic design of the yielding pile-shafts is to replace the pile-soil system by an equivalent fixed-base cantilever assuming the equivalent system has the same global response as that of the pile-shaft (Budek et al. 2000; Chai 2002). In this method, plastic curvature is concentrated at the center of the equivalent plastic hinge below ground surface. Prior knowledge of plastic-hinge length is essential for proper assessment of assess plastic displacement at the top of the pile-shaft. Unfortunately, existing recommendations for estimating plastichinge length are largely incomplete and/or inadequate.During the last two decades, several relationships have proposed for evaluating the equivalent plastic hinge length, Lp, based on experimental and numerical studies. Budek et al. (2000) conducted numerical modeling to calculate the plastic-hinge length of piles embedded in cohesionless soil. They found that the plastichinge length varies linearly with both soil stiffness and aboveground height, e. Chai and Hutchinson (2002) conducted full-scale experimental tests on reinforced concrete piles in sand. They reported that Lp depends primarily on the aboveground height of the pile, neither sensitive to the soil stiffness nor to the value of displacement ductility factor. They stated that the equivalent plastic hinge length is relatively independent of the displacement ductility factor and is not very sensitive to the change in soil density. On the contrary, Goel (2014) and Liu et al. (2016) conducted nonlinear numerical analyses which revealed that Lp changes with the displacement ductility factor and even suggested that using different values of Lp for different seismic design levels is essential for a reliable estimation of the ductility capacity."

Jan 1, 2017

By RavikiranVaidya, Vishal Dhamecha

Low Strain Pile Integrity Testing has been used in India since 1990’s and several have tried to demonstrate the utility and benefits of this method. However, use of this technology was limited till 1998 as not enough data maybe was not available to justify its use and application on major infrastructure and real estate projects. The first author has done significant work in this method resulting in its use in practically all sectors of the industry that use concrete bored pile foundations as a supporting element. The paper explains various signal enhancers or modifiers involved in processing of low strain test data and its implication on the final output. It also describes how the method can lead to abuse or can provide poor interpretation if incorrectly used. The current effort is to demonstrate that data collection and evaluation becomes complex with changes in soil stratum and pile profile. The paper highlights the present testing practices and provides a guideline for classification of pile integrity into few simple categories in Indian context rather than writing complex interpretations.

Sep 1, 2022

By Abhijit Saha

"The stone columns improve the performance of foundations on soft and loose soil due to the ability of composite ground to sustain increased structural loads under reduced settlements. The interaction between the two basic elements: the ambient subsoil and installed column, present a complexity of behaviour, both in terms of applied stresses and resulting strains. Moreover, as the same is provided in-group in a regular array beneath foundations, the performance of an individual column is likely to be influenced by the presence of neighbouring columns. The present paper addresses this very issue. Analysis of reported field hydro-test data of large diameter oil storage tanks in soft ground in reference to some existing theories led to the development of the stone-column ‘group efficiency factor’. In order that such factor is of general use, it was felt necessary to examine the applicability of the factor to different sizes of groups under varied subsoil conditions. With this in view, some model test results reported in literature of single and group of columns have been analysed and in the process an explicit relationship regarding the stone-column ‘groupeffect’ could be established.INTRODUCTIONThe field application of the stone column technology has gained momentum than the intricate design methodology due to its simplicity in installation and intuitive performance. The ground improvement is due to the complex interaction within the ‘unit-cell’ comprised of the installed column in ambient ground under sustained vertical stress; in association with the interdependence of problem geometry and material properties of the two different soils-one 'native' and the other 'back-filled'. The beneficial effects are increased load capacity, reduction in total and differential settlements, minimization of post construction settlements effected by accelerating consolidation, reduced risk of soil liquefaction, aiding in improvement of slope stability of embankments and natural slopes and effecting changes in the dynamic response. The ‘unit-cell’ concept of a tributary soil cylinder encapsulating an installed column with some reasonable assumptions and boundary conditions (Aboshi et al, 1979; Balaam & Booker, 1981; Van Impe & De Beer, 1983; Priebe, 1976; Saha & De, 1994; Saha; 2005, 2006, 2007, 2011, Saha & Das; 2007) deals with the load-settlement behaviour of the composite system. The present investigation is based on published field data from literature & validated with experimental study reported in literature. The study addresses the effect of group interaction of stone columns beneath a large area loading on ground settlement. The hydrotest load-settlement data of 12 large diameter oil storage tanks founded on stone column reinforced soil at Haldia1 and Kandla2 refinery sites in India; reported by Som (1997), has been analysed to quantify the group efficiency. The results as obtained are compared with experimental study on 2, 3 and 4 stone column groups at different spacing-diameter ratios in soft clay3 reported by Rao et al (1997) to validate the above analysis. A unique relationship between the column spacing and group efficiency has been obtained."

Jan 1, 2015

By Guo Qian, Du Guangyin, Deng Yongfeng, Liu Songyu, Wang Ningping

"Metakaolin (MK) can efficiently enhance the strength and the impermeability of concretes and mortars. However, it has rarely been attempted in admixtures of cement-stabilized soils until presently. As deep mixing method is wildly used in ground improvement, the strength of cemented soils (soilcrete) and the applicability of the MK should be considered. This paper focuses on the macro-strength development of cement-stabilised silty soil mixed with MK. The result shows that the addition of MK can enhance the unconfined compressive strength of the soilcrete, which attributes to a combination of the rates of OPC hydration and the MK-CH reaction. Note that the strength of soilcrete was influenced by the properties of soil, water-to-binder mass ratio (W/B) in admixtures, which needs to be reconsidered since the binder mass composes that of cement and MK totally.INTRODUCTIONCement was used in ground modification techniques, such as the jet grouting, deep mixing method (DMM) which was put into practices in Japan and Nordic countries in the middle of the 1970s, and then spread to China, South East Asia[1]. For last decades, fly ash, slag or silica fume was mixed with cement to form the new cement base stabilizing agent in the view of economy and performance improvement. The mechanical behavior of these soil-binder admixtures (nominated as “soilcrete”), was investigated. But the soilcrete modified with the metakaolin (MK) was still not investigated much and lots of further work needs to be conducted.Some laboratory experiments of the soilcretes modified with MK have been taken[2~4]. Kolovos et al. (2013) indicates that the unconfined compressive strength has a more significant improvement when W/B equals 0.4 than that when W/B equals 1.20 concerning the water-to-binder mass ratio (W/B). Sonebi et al. (2013) investigates the mechanical behaviors of cement grouting containing MK with W/B equals 0.4, and also found the effectiveness of the addition of MK. Zhang et al. (2014) performed the studies on Lianyungang marine clay improvement showed that MK obviously enhanced the quality of cemented soils.In this paper, the strength of soilcrete modified with MK is further investigated, where the unconfined compressive strength at different curing time, the content of MK and cement (w/w) in lab conditions was discussed."

Jan 1, 2015

By Mohammed Faizal, Abdelmalek Bouazza

"The operation of ground source heat pumps combined with foundation piles can have an effect on the thermal behaviour of the pile and the surrounding soil. This paper presents the effects of continuous heating, continuous cooling, and alternate heating and cooling operations on ground and pile temperatures as well as the thermo-mechanical behaviour of a field scale energy pile. The effect of pile operation on the ground temperatures is highest near the pile and reduces with increasing radial distance. The results of the present studies generally showed that the thermal elasticity of the pile is not affected.INTRODUCTIONGeothermal energy piles are foundation piles used as underground heat exchangers to maintain thermal comfort in buildings, via the use of ground source heat pumps (GSHPs). Ground source heat pumps are more economical and environmental friendly compared to conventional heat pumps. Energy piles can be combined with supplemental surface heaters or coolers, known as hybrid systems, for forcefully recharging the ground during non-operational times of the GSHP. Alternative heating and cooling of the GSHP improves geothermal energy usage and alleviates heat build-up in the ground and provides a balance of ground temperatures around the heat exchanger (Jalaluddin and Miyara, 2012).The temperatures induced in the piles during GSHP operation can lead to a complex response of thermal strains and stresses in the pile concrete. An assessment of the thermo-mechanical response of energy piles for various thermal loads may assist engineers in the design process. Furthermore, an assessment of ground temperatures will also highlight any potential thermal interactions with other energy piles in actual building operations.At present, the thermal strain and stress distribution in field scale energy piles has mostly been studied for continuous operation (Laloui et al., 2006; Bourne-Webb et al., 2009; McCartney and Murphy, 2012; Akrouch et al., 2014; Mimouni, 2014; Murphy and McCartney, 2014; Murphy et al., 2014; Wang et al., 2015). These studies have contributed considerably to the understanding of the axial thermal strain and stress distributions in the piles and have shown that pile thermal behaviour is mostly thermo-elastic without inducing major structural concerns.The present paper adds to the current knowledge by assessing the pile thermo-mechanical and ground thermal response for continuous and alternating thermal loads of a field scale energy pile. The operation modes studied are 24 hours continuous cooling (Faizal et al., 2015), 24 hours continuous heating, (Wang et al., 2015) and alternate heating and cooling operation (Faizal and Bouazza, 2016). The forced ground thermal recharging is done during the non-operating times of the cooling unit, simulating a solar hybrid GSHP system for a scheduled intermittent mode of operation."

Jan 1, 1900

By Jeffrey C. Evans, Daniel G. Ruffing, Hejintao Huang

Soil-bentonite slurry trench cutoff walls are the most common type of vertical cutoff wall used in the US for seepage control and for passive control of contaminant migration at environmental sites. Design considerations are often limited to constructability considerations and a target hydraulic conductivity. With design-build contracts common, the backfill design is often left to the contractor. As a barrier soil, the hydraulic conductivity of bentonite slurry wall backfill is typically required to be equal to or below 1x10-7cm/s. The importance of stress state upon the hydraulic conductivity as well as the expected stresses are both established in the literature. Grain size distribution of the base soil and bentonite content both affect compressibility and hydraulic conductivity. This paper describes the results of studies undertaken to evaluate the interrelationships between compressibility, hydraulic conductivity, grain size distribution, and bentonite content. Three base soils were used representing a range of soils found on typical construction projects. Using these base soils, mixtures containing a range of dry bentonite contents from 0% to 5% were prepared to a slump consistent with field practice. The compressibility and hydraulic conductivity were measured in consolidometers adapted for falling head permeability tests at the end of each load increment. These experiments yielded the relationship between effective stress and hydraulic conductivity as well as consolidation characteristics including time rate of consolidation and coefficients of compressibility. The experimental results are then used to indirectly evaluate stress development and to assess the time needed for consolidation. The findings show a substantial decrease in hydraulic conductivity as effective stress increases, regardless of base soil type and dry bentonite content, a relative insensitivity of stress development to backfill compressibility, and a wide range of values for coefficient of consolidation depending upon backfill mixture and stress level.

Jan 1, 2016

By Ramin Motamed, Fahim M. Bhuiyan, Raj V. Siddharthan, Joseph Toth

The difficulty in material characterization and the erratic response of cemented soil layers, such as caliche in the Las Vegas valley, creates challenges for practicing engineers to reliably predict the response of deep foundations. The focus of this paper is the numerical prediction of axial response in drilled shaft foundations, which are commonly used in infrastructure projects (i.e., bridges and tall buildings) in Las Vegas, NV. The prevalence of hard caliche layers with variation in the degree of cementation add to the complication in numerical modeling. In this study, the applicability of two existing t-z models, developed for Florida limestone and soft rock, was evaluated based on numerical simulations of three bi-directional load tests conducted at caliche-dominant sites. The corresponding top-down load tests were also simulated for further assessment. A MATLAB-based finite-difference program, NVShaft, has been used to implement the mentioned t-z models in axial load analysis. Complexity originating from drilled shaft construction and the interaction with caliche during one axial load test resulted in a stiffer predicted response compared to measure data. For the other two load tests, both t-z models produced comparable load-displacement responses. It was observed that the t-z model for Florida limestone predicted relatively stiffer responses and higher drilled shaft capacity.

Sep 8, 2021

By Anahita Modiriasari, Benjamin S. Rivers

Measurement while drilling (MWD) is a subsurface exploration technique associated with real-time and continuous monitoring and recording of drilling data during the drilling process. This technique can be used for underground investigations to differentiate ground strata, detect the presence of fractures and voids, and evaluate geological features and mechanical properties of geomaterial. When MWD is used for geotechnical investigations, it can improve site characterization, identify variable conditions, improve design and construction, lead to shorter project delivery times, reduce the cost and risks associated with limited subsurface data and geotechnical uncertainties, and maximum return-on-investment. Given these benefits, MWD is gaining attention among transportation agencies and the geotechnical industry. Federal Highway Administration’s (FHWA’s) innovation deployment program “Every Day Counts (EDC-5)” includes the implementation of Advanced Geotechnical Methods in Exploration (A-GaME), which aims to implement effective, underutilized subsurface exploration methods, including MWD, in U.S. practice. This paper provides an overview of the MWD technology for geotechnical site investigations and presents a case history where MWD was employed to design deep foundation for the construction of a building in Massachusetts. The advantages of this technology for risk reduction and project cost and time saving are also discussed.

Oct 1, 2022

By Leena Korkiala-Tanttu, Noora Lindroos, Juha Forsman

"Construction works at the Helsinki city sea shoreline requires dredging and handling of contaminated sediments. Most of these soft dredged sediments are regarded as too poor quality material for earth construction purposes. Mass stabilization technology has been applied to improve the technical and environmental properties of the dredged sediment in order to utilize the material in construction. The treatment site presented in this article is placed in the West Harbor where the dredged sediments are disposed in basins, mixed with binders by mass stabilization and transported to utilization sites. The volume of these basins is about 90 000 m3. So far these basins have been used three times during the years 2011-2014. The most applied binder has been cement. Its high price and carbon footprint have encouraged use alternative binders. Other used binder materials include fly ash and end product of desulphurization from coal combustion, and fly ash from combustion of Estonian oil shale. The technical and environmental properties of stabilized sediments have been studies in the laboratory and in situ thoroughly. Some properties of the stabilized sediments which have been studied are: compression strength, modulus, hydraulic conductivity, leaching of contaminants, etc. The leaching test results show that heavy metal leaching is very low with all binder materials tested.1. INTRODUCTIONContaminated marine sedimentsMarine sediments in the coastal areas are often contaminated as a consequence of industrial and port activities, as well as the influence of cities located there. Construction activities and reclamation of shore line require dredging and handling of contaminated sediments since the level of contamination inhibit dumping of dredged sediments into the sea. Based on their technical properties, most of these dredged soft and watery sediments (clay, gyttja, etc.) are regarded as too poor quality material for earth construction purposes. Economic, sustainable and environmentally safe management of contaminated, dredged sediments is a key issue in many construction sites.In the City of Helsinki, mass stabilization technology has been applied to improve the technical properties of the dredged sediments in order to utilize the material in construction. Owing to stabilization / deep mixing / solidification, also the contamination is encapsulated in a monolithic solid of a high structural integrity. Thus, contaminants migration is restricted by the decreased surface area exposed to leaching.The treatment site presented in this article is placed in the West Harbor (a place of Helsinki called Jätkäsaari) where dredged sediments are disposed into stabilization basins, mixed with binders by mass stabilization and then transported to final utilization sites. The location and principle of these basins is presented in Figures 1-4. The overall volume of these four stabilization basins is about 90 000 m3."

Jan 1, 2015

By Donald A. Bruce

"The Deep Mixing Methods (DMM), in their current forms, have been employed in the United States since 1986, although an earlier version had seen service from 1954. The earlier developments were strongly influenced by practices in the Nordic countries and Japan, while by the late 1980’s several DMM systems had been developed in the U.S. itself. Since then, DMM has continued its evolution, principally via the challenges of a series of large, landmark projects, but also via distinct, significant technological advances. This paper highlights the key points in the history of DMM in the U.S., and provides an overview of the different methods currently in use.IN THE BEGINNINGIt is a common misconception that the history of applications of the Deep Mixing Methods (DMM) in the United States dates from 1986 when SMW Seiko Inc. — a subsidiary of Japan’s Seiko Kogyo Company — was established in the Bay Area. However, the author believes that Intrusion Prepakt Co.’s patented MIP (Mixed in Place) system had been used, albeit sporadically (about 30 projects are recorded), since 1954 (FHWA 2000, 2001). Ironically, by 1961 this single auger method had been extensively used under license in Japan for excavation support and groundwater control — by the Seiko Kogyo Company. By 1972, the original MIP technique had been succeeded by more advanced Japanese methods, involving multiple augers. Intrusion Prepakt have long since become defunct.The first systematic studies of contemporary Deep Mixing Methods in Japan began in 1967 when the Port and Harbor Research Institute of the Ministry of Transportation began laboratory testing using granular and powdered lime for treating soft marine soils. Fundamental studies continued through the early 1970’s, by which time the development of industrial scale equipment was well advanced, having its first application on a marine trial near Haneda Airport. Coincidentally, laboratory and field research also began in 1967 in Sweden (“Swedish Lime Column Method”) for treating soft clays using unslaked lime. Reportedly the progenitor was a Norwegian, Kjeld Paus, who had made observations on fluid lime columns in the U.S. It would seem that developments in Japan and the Nordic countries proceeded independently until 1975 when the technology leaders from each group (Broms and Boman; and Okumura and Terashi, respectively) presented their — very similar — findings at a conference in Bangalore, India. Limited technical exchanges ensued thereafter.Whereas the Nordic developments continued to focus on the use of dry reagents (cement and lime) and relatively light equipment compatible with operating on and in very soft clays and organics, the Japanese progressed into the use of fluid reagents (cement-based grouts) and heavier equipment for both marine and land-based projects. Thus, by 1986, there were a large number of proprietary (wet and dry) DMM systems in Japan, and a rapidly growing market already by then accounting for over 12,000,000 m3 of ground treatment."

Jan 1, 2015

By Peter J. Nicholson

"IntroductionDuring my more than 40 years in the practice of underground construction and engineering, the industry has seen progress from the dig down to rock or hardpan or alternatively drive concrete or steel into the ground and count the blows; then you can be sure of you have a solid foundation; to the modern day, I’m willing to try anything to save money. Of course these are both exaggerations, but not gross ones. After getting bored being supervision on jobs counting blows, I struck out into the new field of “tie-backs” as they were called in the United States, or “ground anchors” as they were then termed in the United Kingdom. After installing some of the first permanent ground anchors for the Corps of Engineers on Lake Michigan as well as the highest loaded rock anchors of the time at two dams on the Ohio River, we were at the top of our game in the 1970’s. Subsequently in the 1980’s when my view of the future of ground anchors saw their installation becoming a commodity item, we branched out into “Pin Piles” now known as Micro Piles, high capacity, steel tube encased, small diameter (5-12” or so), high capacity (100-500 tons) piling. Next came soil nailing, both temporary and permanent retaining walls, as at Cumberland Gap Kentucky. My next morph was into “Cement Deep Soil Mixing” earlier on, known simply as “soil mixing”. For this education I traveled to Japan several times and established a long-term, Joint Venture, relationship with one of the better known Japanese specialty ground modification companies. In Boston at the “Big Dig” we established the then record size soil mixing project, 500,000 or so cubic meters of CDSM concluding in the year 2000. Since then I’ve been involved as a consultant mainly for dams and levees. Below is the story of how I came to be at this place in the road to innovation in Geotechnical processes."

Jan 1, 2017

By Peter J. Nicholson

During my more than 40 years in the practice of underground construction and engineering, the industry has seen progress from the dig down to rock or hardpan or alternatively drive concrete or steel into the ground and count the blows; then you can be sure of you have a solid foundation; to the modern day, I?m willing to try anything to save money. Of course these are both exaggerations, but not gross ones. After getting bored being supervision on jobs counting blows, I struck out into the new field of ?tie-backs? as they were called in the United States, or ?ground anchors? as they were then termed in the United Kingdom. After installing some of the first permanent ground anchors for the Corps of Engineers on Lake Michigan as well as the highest loaded rock anchors of the time at two dams on the Ohio River, we were at the top of our game in the 1970?s. Subsequently in the 1980?s when my view of the future of ground anchors saw their installation becoming a commodity item, we branched out into ?Pin Piles? now known as Micro Piles, high capacity, steel tube encased, small diameter (5-12? or so), high capacity (100-500 tons) piling. Next came soil nailing, both temporary and permanent retaining walls, as at Cumberland Gap Kentucky. My next morph was into ?Cement Deep Soil Mixing? earlier on, known simply as ?soil mixing?. For this education I traveled to Japan several times and established a long-term, Joint Venture, relationship with one of the better known Japanese specialty ground modification companies. In Boston at the ?Big Dig? we established the then record size soil mixing project, 500,000 or so cubic meters of CDSM concluding in the year 2000. Since then I?ve been involved as a consultant mainly for dams and levees. Below is the story of how I came to be at this place in the road to innovation in Geotechnical processes.

By Rick Piovesan, Pramod Rao, Nihal Bohra, Mark Wahler

"This paper discusses the approach followed for the geotechnical design of 355 mm and 457 mm diameter driven open-ended steel pipe piles used for a gas plant at a green field site in Pilbara region in Australia. The principal bearing layer at the site comprises of calcareous Red Bed soils and weak rock, which is the typical geology along a significant length of the northern Western Australian coastline with carbonate content up to 70%. The uncertainty associated with the mechanical behavior of the calcareous soils and cemented soils (weak rocks) presented design challenges in the selection of appropriate pile design method and design parameters for pile capacity estimation during Front End Engineering Design (FEED). The American Petroleum Institute (API)-based design methodology was adopted. The representative design parameters for the Red Bed weak rock were established by treating the weak rock as clay with undrained shear strength as one-half of the characteristic unconfined compressive strength (UCS) value. Both statically load tested and CAPWAP (Case Pile Analysis Wave Program) estimated ultimate axial pile capacities on 25 early pre-production indicator piles demonstrated that the API design methodology for siliceous soils provides reasonable prediction of axial pile capacity in the red bed soils/weak rock and no reduction to API computed axial capacity due to carbonate content is warranted. The results also demonstrated that penalizing axial pile capacity solely based on carbonate content is not appropriate.IntroductionA gas processing facility was proposed to commercialize the gas reserves located 130 km offshore from the north-west coast of Western Australia (WA). The project site is a green field site located in the Pilbara region along the northwest coast of WA. Specific information regarding the site has been withheld due to confidentiality reasons. The site layout is shown in Figure 1.The site comprises low-lying tidal flats, clay pans and sand dunes covered with low scrub. The onshore site levels vary from elevation 1 m to 10 m AHD (Australian Height Datum), with the largest proportion of the area (excluding sand dunes) between elevations of 1 m and 3 m.The onshore facilities are to comprise a liquefied natural gas (LNG) plant site, a construction camp, the land-based portion of the materials offloading facility (MOF), roadways, and borrow pit areas.The existing ground levels within the process train area, where pile load testing was performed, vary from over 7 m AHD where the summits and peaks of the central dune exist to typically 1 m to 2 m AHD towards the east and west edges of the dune. The proposed finished grade for the process train is set at 7 m AHD."

Jan 1, 2015

By Tanaya Deb, Sujit Kumar Pal

"Experimental investigations are carried out on failure pattern around 2D models of belled anchor piles in dry sand bed of density 15.60 kN/m3 under uplift. The models are having thickness ratio (Ts/Tb) = 0.28, 0.32, 0.38 and 0.46 and total 12 numbers tests are performed on models possessing 45° bell angle and shaft thickness 26 mm. The foundation bed is prepared with alternate dyed and non-dyed sand layers and continued upto reaching embedment ratio of 3, 4 and 5 for each width ratio. The failure points are presented with respect to meridian section of anchor in X-Y coordinate system and the equations formed are of polynomial of degree 3; and R2 values are near about 1. The developed wedge is implemented as three-dimensional axisymmetrical failure surface around similar 3D models. In the horizontal slice method vertical limit equilibrium is used for calculating weight of wedge and mobilized shear (as per Chattopadhyay and Pise, 1986) on the slip surface of each element. The summation of all elementary forces demonstrates gross uplift capacity. The initial and final failure angles are detected and parametric study is conducted on failure pattern as well as predicted net ultimate uplift capacity. Almost all the analytical data are within ± 10% variations with respect to the experimental results of uplift capacity which shows better correlations. INTRODUCTION Belled or enlarged base anchor piles are attractive and economic alternative to the geotechnical engineers for compressive load bearing capacity as well as tension anchorage. These types of anchors may be useful for foundations erected below ground water table. In light weight structures like radar tower, television tower, power pole and outdoor sign pools imbalance horizontal forces due to wind loads, are more than of those self-weight of those structures. Due to chronic tensile loads most possibly from wind loads and associated imbalanced cable tension, the legs of power transmission tower should be properly designed to be safe against resultant pull-out forces. In belled anchor pile, uplift is influenced by embedment ratio, diameter ratio; so, contributions of these parameters on failure surface influence uplift capacity. Balla (1961) first introduced non-linear failure surface in the pattern of circular arc based on Kotter’s equation (1903) and soil friction was assumed to act on slip surface. The predictive mathematical models established by Matsuo (1967), Rao and Kumar (1987), Chattopadhyay and Pise (1986), Saeedy (1987) and Ghaly and Hanna (1994); it was reported that net ultimate uplift capacity was combination of bulk weight of failure wedge and shear resistance along slip surface acting in opposite direction of wedge movement. From the literatures available till date, it reveals that the contribution of mobilised shear and weight of breakout wedge separately, demanding for more clarification depending on the on parameters like embedment ratio, diameter ratio."

Jan 1, 2015

By Andrew McNamara, Stuart Norman, Matthew Dearing, Michael Pelken, Asha Panchal

The deep foundations industry has largely remained unchanged since in the advent of CFA piling in the 1960s. Piles have consequently been designed and constructed following the traditional codes and standards without much regard for optimising in-life efficiency or end-of-life reuse. After existing developments have been demolished there is little motivation to reuse existing piled foundations as their load bearing capacity and structural integrity cannot be verified. Therefore piling contractors are increasingly spending more resources on coring through existing piles, only to be replaced with larger diameter or deeper piles. The hollow element of the HIPER® Pile provides access to the entire length of the pile to permit inspections and a shaft in which the pile can be extended if needed. This paper presents and compares the embodied carbon savings, both during construction and through foundation reuse, from a HIPER® Pile scheme compared with the traditional solid pile scheme. A discussion on the benefits of this technology and its implications on warranties and approvals is also presented to motivate the foundations industry to embrace whole lifecycle assessments and support the journey to net-zero carbon.

May 1, 2022