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By John R. Grillo, Gordian Ulrich, Franz-Werner Gerressen

Most geotechnical construction professionals are aware of piling using hydraulic drill rigs and the so-called Kelly drill mode. Kelly drilling has many advantages as it can work with a wide range of tools facing almost all types of soil and rock conditions. Kelly drilling can also deal with diameters up to 10 ft (3.00 m) and bigger or depths of more than 330 ft (100 m). Nonetheless, there is a concern about Kelly drilling as it is a relatively slow installation process. Therefore, an alternative piling method like Cased CFA (CCFA) Piles (Cased Auger Cast Piles) provides a significant advantage in terms of installation performance, schedule and cost saving potentials. Major application for the Cased CFA system is the secant pile wall construction. Against the traditional secant pile wall systems like fully cased bored piles or CFA secant piling the Cased CFA secant pile wall system has the advantage in cost and time against the fully cased system and in quality against the standard CFA system. This paper will describe the methodology and installation process in general as well as first reference projects carried out in the United States. This paper will present the results in cost and schedule saving using this method. In addition, we will also describe the limitations of this method. INTRODUCTION In the changing construction environment, companies are searching for new technologies or improvement of existing technologies to complete their projects in shorter time frames to provide a good economic solution. Especially with the focus of increasing urbanization, the aim of fast construction becomes more and more important. When thinking of piling, most people will have the same picture in mind: that of a hydraulic drill rig working in Kelly drilling mode; however, the perpetual drill rig development provides a number of options for the execution of specialist foundation projects, either for foundations or for pile walls when using single pass applications like CFA, Cased CFA and Full Displacement Piling (FDP). Single pass means, in general, that the tool is pushed and rotated into the ground to the final depth in one stroke. After reaching the final depth, concreting is started and concrete is pumped continuously while the tool is withdrawn.

Jan 1, 2019

By Malek Smadi, Yazen A. Khasawneh

"New embankments were constructed mostly on soft clays as part of interstate I69 extension in southern Indiana. The embankments serve as bridge abutments and as part of the fill sections along the interstate extension alignment. The height of the embankments range from 50-ft to 125-ft with a maximum foundation thickness of about 75-ft. The foundation soils comprise relatively high compressible fine grained soils. A fully coupled Hydro-Mechanical numerical simulations were conducted for optimizing the construction stages of the embankments. The objective of the staged construction is to allow for sufficient effective stress and undrained shear strength gain to ensure foundation stability under the stage load. Wick drains were utilized to shorten the drainage path and thus accelerate achieving the required undrained shear strength. The extensive field investigation and laboratory testing programs provided a good understanding of the subsurface conditions and allowed the use of a relatively advanced soil constitutive model in the numerical simulations of the staged construction. The effectively designed instrumentation program allowed for monitoring the settlement and pore water dissipation during construction. The pore water pressure, and surface and subsurface settlements from the numerical model predictions reasonably agreed with the instrumentation data over the construction period.INTRODUCTIONThe stability of soft fine grained foundation soils due to embankment construction is dependent on the undrained shear strength of such soils. The permeability, compressibility, and drainage boundaries control the foundation soils response (settlement magnitude and rate) to loading. The settlement magnitude is a function of minerology and soil structure. The settlement rate which is equivalent to the rate of excess pore water pressure dissipation is a function of the soil permeability and drainage boundary. The dissipation rate control the evolution of effective stress and thus the gain of undrained shear strength. As such, if the increase in total applied load is controlled such that enough time is granted for the evolution of the total stresses into effective stresses, then the stability of the foundation soils is enhanced by the gain of the undrained shear strength. The controlled application of the total stress is the definition of the staged construction. From the definition of the staged construction, it is obvious that the process is a coupling of the hydraulic and mechanical responses of the foundation soils."

Jan 1, 2017

By Bernard B. Vannoy, Howard W. Gault, Ramesh Bobba

"Treviicos-Soletanche Joint Venture (JV) and the US Army Corps of Engineers (USACE) have installed a 3800-foot long, 275-foot deep and minimum 2-foot wide secant pile barrier wall at Wolf Creek Dam in Jamestown, KY. This paper describes the methodology employed by the JV and USACE to evaluate the overlap, thickness, and position of the barrier wall. It addresses the contractual requirements, positional uncertainty, and evaluation procedures.These procedures evolved over the course of the project as various issues were identified and procedures developed to evaluate these issues. During the project, it became clear that the JV and USACE could ascertain that the wall thickness and overlap requirements could be met if the overlap based upon Koden data was at least 0.7’ in the left-right direction. For a small number of piles with overlaps between 0.5’ and 0.7’, the piles are contractually compliant yet contain a minor degree of uncertainty in the overlap. Initially, the USACE assumption was that the amount of uncertainty of verticality measurements would require more than a 1-foot measured overlap in the left-right direction to confirm an actual, contractual 6-inch overlap. With time and experience, the limit of measured overlap was reduced in accordance with greater understanding of the equipment capabilities and tolerances. Other lessons learned include the need for Quality Control/Assurance personnel to collect data at the same starting point for every pile.For every pile the JV and USACE compared analog and digital data to provide confidence that the correct digital data was used for overlap calculations. Perhaps the most important lesson learned was the importance of the JV and USACE working together and sharing all data. Overlap analysis was performed by the JV’s Barrier Wall Specialist and a small number of USACE personnel. This resulted in a high level of experience and expertise within a small group.IntroductionThe Treviicos-Soletanche Joint Venture (JV) and the US Army Corps of Engineers (USACE) have installed a 3800-foot long, 275-foot deep, and minimum 2-foot wide secant pile barrier wall at Wolf Creek Dam in Jamestown, KY. The wall was installed through a 6-foot wide Protective Concrete Embankment Wall (PCEW) which was installed two feet into rock. The PCEW protects the embankment from erosion of drilling fluids during subsequent operations. Below the PCEW the piles were installed to a specified elevation (staggered at 475’ and 473’ below the 748.2’ work platform). The Ordovician limestone and shale bedrock is flat lying with few vertical fractures. These conditions facilitate the advancement of pilot holes with very low deviations (with considerable credit to the JV’s drillers and steering engineers). The pilot holes were spaced on 31.5-inch and 35-inch spacing. Subsequent enlargement of the pilot holes to 50’ resulted in a continuous wall. This paper addresses the requirements and procedures to assure that the wall was as wide, deep and continuous as specified."

Jan 1, 2015

By Chengcan Wang, Jin-Tae Han, Young-Eun Jang

"The waveform micropile is a newly developed foundation type for increasing the bearing capacity with the created shear keys on the pile’s shaft. Analyzing the increment of resistance at the shear key zone is a crucial factor in the design of the waveform micropile. Hence, centrifuge tests were carried out employing six different models, including a waveform micropile in the axial loading condition. The analysis results of the load-settlement curves showed that the waveform micropile achieved a higher bearing capacity compared to the micropile without shear keys. In addition, the test results revealed that the load-settlement relationship was affected not only by the pile shape but also by the locations of the shear keysINTRODUCTIONA micropile is a small-diameter pile, typically constructed with a less than 300 mm diameter. Generally, the micropile’s construction involves drilling, grouting, and insertion of a reinforcement material, such as a thread bar. The micopile can be utilized in a variety of fields for reinforcing the foundations of existing structures. It also has advantages for accessing challenging areas like limited-access construction sites, including those with a low headroom space and adjacent structures, due to the small size of the construction equipment. Thus, since it was introduced in 1950 in Italy, the micropile has become one of the preferred solutions when other deep-foundation methods are not applicable to the site.Federal Highway Administration (FHWA) gives the micropile design implementation guideline of neglecting the end bearing due to its small diameter but considering the frictional resistance if the bond zone of the pile is in the soil or on a weak rock. The bearing capacity is considered primarily only if the micropile is founded on a high-quality sound rock (FHWA, 2005). Micropile design in South Korea is currently being performed based on the FHWA manual and taking into consideration the frictional resistance for the design as the pile generally sockets into a weak rock or soft rock. Moreover, the frictional resistance within the soil layer has usually been ignored, considering only the shaft resistance of the rocksocketed length in the conservative design. The design concept excluding the frictional resistance in the soil layer, however, may lead to an extension of the pile socket length, which will increase the construction cost. Hence, many researches have attempted to provide better design and construction methods to increase the bearing capacity in a cost-effective way (Juran et al. 2001; Sadek and Isam 2004; Tsukada et al. 2006; Finno 2002; Gomez et al. 2003; Seo et al. 2013)."

Jan 1, 2016

By Robert Thurner, Albin Norrman, Sami U. Raja

The West Link is a double track railway project currently under construction in Gothenburg, Sweden. The project includes the construction of 8 kms of track, 6 kms of which will be in tunnels. Beside several large excavations, three new stations will be built: Centralen, Haga and Korsvägen, all within the city of Gothenburg. The first construction phase of the project began in May 2018, and the finalization of the project is expected in 2026. The project is divided into five sections. Keller is involved in four of these contracts since the design & planning phase in 2018 assisting the special foundation works with various geotechnical techniques including Dry deep soil mixing (DDSM), jet grouting, rock grouting, uplift piles, sheet piling and rock dowels. The core idea behind successful collaboration has been to apply the right product for a location specific challenge which can help optimise costs & time for the project with a minimal environmental impact. Due to the extensive nature of the project, a team of experts from various locations around the world is helping design and execute various foundation technologies and providing solutions to the practical challenges in the project like working close to existing structures, rail lines, river etc.

May 1, 2022

By Andhra Pradesh, Nagarajkumar B. V

As a part of Mumbai City Mega Drinking Water Project at Amar Mahal Tunnel-1 Ghatkopar East Mumbai, drinking water tunnels were proposed by MCGM from Amar Mahal to Trombay reservoirs, Amar Mahal to Wadala and further up to Parel. The pipeline has to be underground and laid at a depth of 5.5m. The initial proposal was to provide sheet piling to enable the safe excavation and installation of underground pipeline. However, installation of sheetpiles was practically not feasible due to the existing soil strata for driving the sheet piles. Hence, it was proposed to install micropiles instead of sheet piles. In this paper we discuss about the purpose, basic design, detailed design approaches and actual work implementation of micro pile with temporary struts for shoring protection works in this project.

Sep 1, 2022

By Toshio Yonezawa, Helmut Florian, Herbert Kuh, Masamichi Aoki, Takao Koono, Franz-Werner Gerressen

"To increase the bearing capacity of the ground, soil improvement technique is often adopted. One advantage of soil improvement techniques is the fact, that the impact to the environment is low, as the system utilizes the existing soil. Recently, compressive strength of soil improvement gets more into the focus for the use of building foundation. To prevent brittle fracture, which is a weak point of soil improvement, fiber reinforced soil improvement has been developed. Laboratory tests were conducted to examine the fibers suitable for reinforced soil improvement, and examine the optimum mix design for fiber cement slurry. Based on the laboratory tests, polypropylene fiber and cellulosic viscosity admixture was selected. For the laboratory tests a scaled model of CSM mixing head was used to examine the dispersion of the fibers in the ground. Using the CSM mixing head, the outer periphery fibers of soil improvement seemed to be arranged in the vertical direction, toughness performance of the soil improvement could be improved. Furthermore, full scale field test was performed using actual CSM unit, modified to enable the use of fiber mixed slurry. The validity of the material as well as the toughness performance of the soil improvement, determined from lab test results, was confirmed. In addition, it was confirmed that fiber reinforced soil improvement can be constructed appropriately by CSM method.2 INTRODUCTIONSoil improvement technique to improve the strength and deformation performance of ground has been used for a long time. Cement improved methods, with the increase of the deep Mixing Method, which has been disseminated since the 1970's, was often used since. Cement used soil improvement technology has been utilized to stabilize excavations, slopes in embankment and much more. Recently, it can be used for preventing liquefaction by building soil improvement in a grid (Suzuki et al. (1996)), and also as basis of the structure by increasing the compression strength of soil improvement (Yamashita et al. (2011)). Cement used soil improvement method, a technique for mixing the in-site soil and cement, can effectively utilize natural resources, and it can be expected that its use will increase further in the future. Therefore, soil improvement technique will be able to minimize the impact on the environment. Cement improved soil is a mixture of soil particles and cement with high compressive strength but low tensile strength. Since tensile strength of soil improvement is low, brittle destruction occurs. Therefore, it is not possible to use soil improvement in conditions acting with bending stress. If a horizontal impact force occurs in the improved soil, the width of the soil improvement needs to be increased to reduce the bending stress. If preventing the brittle fracture of soil improvement, the width of soil improvement could be reduced, then less resources would be needed. In order to increase the tensile strength of the soil improvement, several studies for the mix of fiber and soil were performed. Victor (1992) indicates cracking deterrent effect by fiber based on laboratory tests. Moreover, based on laboratory tests, Hayasaki (1982) illustrated the effect on the tensile strength of the fiber types, the type of fiber, the diameter of and the length of fiber."

Jan 1, 2015

By Luca Pingue, Regine Jagow-Klaff, Franco Muratore, Carlandrea Albonico, Damiano Frontini, Rudolf Wernecké

This paper describes an artificial ground freezing (AGF) application carried out to ensure both watertightness and structural support for the safe excavation of four cross passages of the Forrestfield Airport Link (FAL) project in Perth. The line will deliver 8.5 km extension of the existing urban rail network connecting the growing eastern suburbs of Perth with the existing suburban rail network. The proposed soil improvement technique is adopted as a smart alternative to jet grouting from the surface since the use of heavy equipment with long vertical mast was not allowed due to the line underpassing an airport in operation. In this paper, details of the challenges and lessons learned during both design and construction phases are given. Furthermore, it is described the geometry and the installation of freeze pipes in presence of a massive steel frame, ventilation system and slurry pipes of the tunnel boring machine (TBM) in operation. It is also illustrated the web monitoring system to allow key personnel to follow in real time the development of soil temperatures, tunnel convergences and ground surface deformations as well as changes in the interaction between international parties involved due to the COVID-19 pandemic.

May 1, 2022

By Sunil S. Basarkar, Vinothkumar S

Ground Improvement Techniques serves to improve various engineering properties for supporting various foundations. These may be undertaken either by conventional or advanced methods. The Controlled Modulus Column (CMC), also known as Rigid Inclusion is a soil improvement technique to reduce the total and differential settlement by using semi-rigid soil reinforcement columns. The CMC technique can be executed by displacement or non-displacement methods. It does not aim to bypass the compressive layer or to install a pile that will directly support the entire load from the structure. Principle of the technique is to introduce a load transfer platform between the head of the column and structure and transform a uniform load into soil. Initially, the structural load transmitted into the soil generate the settlement greater than CMC piles. When the settlement between the soil and column became equal at neutral point, maximum structural load shall be balanced by the positive friction and tip resistance to stabilize the foundation without exceeding the allowable settlement limit. This paper describes the behaviour of soil reinforcement with CMC column and their installation process with reference to a project at the Dry Bulk Terminal Port, San Pedro- Abidjan (Western Africa). Methodology of CMC, requirements of Ground Improvement, arrangements and outcome of this method are presented in this paper.

Sep 1, 2022

By Alexander Ciccone, John H. Gill

Jet grouting is a highly versatile ground modification technique that can offer significant commercial and technical advantages over traditional concrete pit underpinning applications. Despite these advantages, jet grouting remains an underutilized technique in the construction industry due to its perceived complexity, cost, and risk. When performed thoughtfully, underpinning by jet grouting offers significant safety and schedule advantages over traditional underpinning approaches. The New England construction market has seen a recent acceptance in the use of jet grout underpinning on congested project sites across a variety of subsurface conditions. The reduction of the cement batch plant footprint due to equipment advances has allowed the use of this technique in urban sites where its use would be previously infeasible. Furthermore, jet grout underpinning has been utilized for support of historic and sensitive structures with generally lower tolerance to settlement than is typically feasible with conventional pit underpinning. Robust, real-time geotechnical instrumentation monitoring systems have helped reduce the uncertainty and further expand the feasibility of jet grout underpinning applications. When properly designed and constructed by qualified and experienced jet grouting contractors, the flexibility of soilcrete for design and construction may be utilized to overcome the many inherent challenges which complicate underpinning and earth retention systems. INTRODUCTION The construction of buildings and infrastructure in our increasingly dense urban spaces often requires excavations below the elevation of existing structures immediately adjacent to the proposed work. Where a proposed excavation system encroaches into an existing structure’s zone of influence, additional measures, such as the construction of an underpinning or excavation support system, are required to safely excavate and minimize the impacts on the adjacent structures. Jet grouting is one method of underpinning that offers significant commercial and technical advantages over many other techniques. Though it was first used to the United States in the 1980s and has grown in popularity elsewhere, jet grout underpinning remains underutilized domestically due to its perceived cost and risk premium. Jet grouting has significant technical advantages over other underpinning methods due to its applicability in a wide range of soil types and its flexibility of design and installation. The jet grouting process is capable of limiting the movement of foundations during construction and excavation to lower thresholds than most traditional underpinning methods (Droof, Furth, & Scarborough, 1995). Its use for underpinning historic and sensitive structures with lower settlement criteria provides additional evidence to its technical utility. Through thoughtful design, adequate planning, and experienced installation, jet grouting can be an appropriate underpinning solution that can provide significant cost and schedule savings.

Jan 1, 2019

By John D. Nelson

Foundation underpinning is a common component of remediation schemes for distressed foundations on expansive soils. For many applications in expansive soil, micropiles have distinct advantages over other techniques. This paper will concentrate on the design and construction of micropiles in expansive soil. It discusses the nature of building distress and the relationship between foundation movement and soil heave. It presents methods for determining the factors that are required for the design of micropiles. Such factors include calculation of expected free-field heave, depth of soil wetting, and prediction of pier movement. A finite element program developed by the authors and others to determine pier heave and internal forces is presented. The input parameters that are required for pier analysis are discussed, and the nature of the output and the sensitivity of the results to the output are described. A case example illustrates the advantages of micropiles over other methods.

Aug 1, 2013

By Yazen Khasawneh, Osvaldo P. M. Vitali, Mohammad Nassim

Wind turbines are subjected to complex form of cyclic loadings with variable amplitudes and frequencies. The cyclic loading and the accumulation of plastic strains with the number of cycles will result in degradation of the foundation soil stiffness. The foundation stiffness degradation will result in a shift (reduction) of the fundamental frequency of the wind turbine. Although this issue is recognized in the guidelines for wind turbines foundation design, no specific provisions are provided in the guidelines to consider the long-term stiffness degradation. In this paper, a practical procedure to consider the long-term cyclic loading effects on the stiffness of wind turbine foundations in cohesive soil is proposed. The procedure is based on 3D FEM modeling and reliable empirical methods to estimate the stiffness degradation due to the cyclic loading. Using the proposed procedure, the long-term performance of the P&H tensionless pier foundation with and without a reinforcing collar at the top of the pier is assessed. The numerical results demonstrated that the long-term performance of the P&H tensionless pier foundation with a reinforcing collar at the top of the pier is outstanding with negligible long-term degradation of the foundation stiffness.

Sep 8, 2021

By Aly M. Mohammad

The design of large diameter drilled shafts in weathered rock has always presented a challenge to the foundation engineers. Degree of weathering and load transfer mechanism through the rock are essential elements required for the design. From the Contractor's perspective specifying the right equipment and estimating the rate of drilling in the weathered rock are key elements for successful construction. The Delaware River Tramway Project has provided an opportunity to address the design and construction of drilled shafts in weathered rock. The Tramway, supported by twin 300-foot towers, will shuttle eight-person gondolas across the Delaware River in about four minutes. Each tower, founded on four high capacity drilled shafts, is designed to resist large axial and lateral loads. At the New Jersey tower, each 7-foot diameter shaft extends 145 feet deep and terminates in weathered Mica Schist. The shafts are situated in the Delaware River where the mud line is approximately 20 feet below Mean Low Water. Below the mud line, there exists a very soft, 20-foot thick layer of organic silt, followed by a 40-foot thick dense sand stratum. Below these sand and silt strata, a 70-foot thick layer of weathered Mica Schist underlies the entire site. Both skin friction and end bearing in the weathered rock stratum were utilized in the analysis to compute the axial capacity. AASHTO and the PennDOT design methodologies were utilized independently during design of the drilled shafts to verify the design. The drilling of large diameter drilled shafts embedded into weathered rock and situated in a marine environment provided a unique challenge in the construction. A permanent steel casing was installed for a specified depth and proper equipment was used to drill and keep the shaft open through the weathered rock. In addition, a 5000 kip Osterberg load test was performed on one shaft to verify design assumptions and confirm the shaft capacity. The results of the test were utilized to establish load transfer characteristics within the weathered rock and to develop foundation design parameters to be used for the remaining shafts.

Jan 1, 2003

By Eleonora Di Mario, Colin B. Turnbull, Matthew G. Mills, Chengbin Miao, Wilhelm S. Degen

"In the past decade, the ‘zero-dredge’ philosophy has become the preferred option for the formation of marine seawalls and reclamations, compared to the partially or fully dredged options, as this solution presents several environmental advantages. Recent relevant project experience is presented herein in order to highlight key design principles and construction issues central to the successful construction and performance of a sloping rubble seawall founded on soft soil improved by stone columns. If designed and installed with proper quality control, correct treatment intensity and sensible construction staging, stone columns are a safe and cost effective method for seawall foundations. This paper provides guidelines with regards to the design, construction and quality control for the correct implementation of stone columns as a foundation element for sloping rubble marine seawalls.INTRODUCTIONBenefits of sloping marine seawalls founded on stone columnsTo suit the current environmental requirements in Hong Kong, recent projects are tending to favour zero-dredge solutions, such as the Hong Kong Boundary Crossing Facility and the forthcoming Three-Runway System. The installation of stone columns allows the underlying deposits, generally consisting of very soft to soft clay and silt (soft soil), to improve in strength to the extent that the seawall can be directly placed on the seabed. This negates the need to dredge the soft soil and, therefore, this ground improvement technique represents an ideal solution for zero-dredge projects.Stone columns can also provide several other beneficial effects, including: accelerated drainage, reduced settlement, increased slope stability and soil reinforcement in the event of an earthquake. Stone columns, in contrast to competing cementitious methods, are a very ductile foundation method. This ductile behaviour is part of the design concept of stone columns in soft soil. Past projects located in Hong Kong and elsewhere, with an improved soft soil layer thickness of over 15m, have shown that stone columns can remain fully functional in terms of both drainage and horizontal reinforcement, even after settlements of over 3m and lateral displacements of up to 1m have occurred."

Jan 1, 2017

By Jeffrey Goodwin P. E., Melih Demirkan Ph. D. P. E., Kevin Tehansky P. E.

Just an hour drive down MD 301 from National Harbor, construction to replace the Governor Harry W. Nice Memorial/Senator Thomas ‘Mac’ Middleton Bridge (HNB) began in spring of 2020. The Maryland Transportation Authority (MDTA) contracted with Skanska-Corman-McLean (SCM) to deliver a new US 301 bridge spanning 1.9 miles from Maryland to Virginia over the Potomac River aiming to improve capacity, safety, and access of the roadway. The project area presented a geotechnical design challenge due to the installation of new bridge foundations in the problematic soils of the Atlantic Coastal Plain alluvial deposits. With the existing bridge remaining in service during construction, and the site’s logistical constraints placing new pile driving operations near existing abutments and piers, a complex instrumentation and monitoring plan was developed to ensure public safety throughout the project. This paper discusses the geological conditions of the project area, the collaborative approach of various design team members to develop an appropriate monitoring plan utilizing various instrumentation, an understanding of baseline conditional movements of the existing bridge, and impact response of adjacent construction activity to help deliver effective new bridge foundations while protecting the old ones.

Oct 1, 2022

By Seth Robertson, Daniel Belardo, Travis Coleman

Thermal Integrity Profiling (TIP) is a non-destructive method used to evaluate drilled deep foundation integrity. This integrity testing method is specified more frequently, and is becoming an industry standard in the transportation and private construction sectors. This testing method utilizes heat generated during the concrete/grout curing process to assess deep foundation integrity over the evaluated length. With compilation of the measured temperature versus time and installation records, a model of the Effective Average Radius versus measurement depth is generated. The generated effective shaft model is highly dependent on specific construction details, subjective modeling parameters, and proper interpretation of concrete/soil heat dissipation characteristics. Key components of the TIP analysis include both qualitative and quantitative assessments. Qualitatively, variations or sharp reductions in temperature profiles may indicate potential anomalous regions. Quantitatively, a correlation is established between measured temperatures and estimated Effective Radii for subsequent integrity evaluation. Best practices in processing the TIP measurements are presented, including selecting the optimal time for analysis, normalizing the thermal profile, and proper interpretation of potential anomalous regions. Recommendations for implementing mitigation efforts and interpretation of the TIP results are presented.

Sep 8, 2021

By P. V. Chandramohan

"The paper deals with the arrangement of structural members for a retaining structure used as a berth in the port of Krishnapatnam. The height of retention is 24.3m. A T-shaped diaphragm wall acts as the retaining surface. A relieving platform has been provided at the top to ease lateral earth pressure on the wall. The diaphragm wall is tied back to a combination of vertical and raker pile. Later, this arrangement was altered to replace the relieving platform with just lowering of ground level below the berth. The tie back was changed to a classical A-frame anchorage. At certain reaches, installation of piles pointing towards the rear was obstructed by a conveyor structure. The anchorage was then changed to include a vertical pile and a pile that points towards the front of the berth. Change in position of inclined pile alters the force in the pile from compression to tension.GeneralPort is a major link in the multimodal transport chain. Berth is the heart of the Port infrastructure. It is here the ocean freight changes to land transport. The change-over, warrants special type of heavy duty handling equipment. The equipment and the process necessitate deep seated foundations. On one side of the berth, deep drafted ships would be berthed. But adjacent to this heavy duty cranes would be operating at the deck level. Berths are of various types. Some are founded on piles and may project into water. Some operators prefer a retaining structure. At the port of Krishnapatnam, a retaining structure was preferred. Dredged level at the berth was to be -20. Deck of the berth was at +4.3. This meant that the height of retention of soil was 24.3m. Ports are generally located near the coast. Subsoil in the port area generally consists of cohesive material of low shearing strength. The berth has to cater to imposed vertical and horizontal loads.Structural functionFor bulk cargo and containers, berth has to support the two crane tracks. These tracks will carry heavy wheel loads of the crane. Besides, the space between the tracks would be used for stacking of cargo or hatch covers. In short, the deck will be subjected to heavy surcharge. This vertical load will manifest as additional lateral force on the retaining wall. Since the height of soil to be retained is high, it is a practice to relieve the lateral earth pressure due to the heavy surcharge of the wall. This is done by providing a relieving platform. The surcharge of superimposed load on the deck and the self-weight of the soil up to a few metres below would be relieved by a suitable platform. This vertical load would be transferred directly to deeper levels through piles. Mooring pull is a horizontal force exerted by the vessel on the bollards towards water side. Berthing force is exerted by the vessel during berthing, through fenders and acts towards land side.Diaphragm walls are usually employed as the retaining face. If the height of retention is less, these walls can cantilever out but in the case of large retention, they have to be tied back. The ties are to be anchored on to suitable arrangements like a dead-man or an A-frame. Berthing structure in the early stages at Krishnapatnam port is shown in fig 1."

Jan 1, 2015

By Kevin Green, Iván Contreras, Aaron Grosser, Jon Ausdemore, Rachel Leier, Amr Ragy

"Construction of a new tailings dam was required to increase tailings storage capacity at a trona mine near Green River, Wyoming. The new dam was founded on overburden soils underlain by both fractured and competent bedrock. The stored tailings and water had high salt content, resulting in salty seepage water. To reduce the impact of the salty water on groundwater and the Green River, the design of the new tailings dam included a 257,260 SF (23,900 m2) seepage cutoff extending into competent rock.An extensive subsurface characterization was performed prior to completing the design and suitable seepage cutoff methods were evaluated. The approach selected was a full replacement panel using hydromill and clamshell for construction and self-hardening slurry (SHS) for the wall material. Laboratory testing was performed and ongoing monitoring has continued to evaluate the hydraulic conductivity and seepage cutoff performance in the briny environment.The paper includes project background, the collaborative approach and outcomes of the QA/QC program, and the monitoring results for the seepage cutoff wall.PROJECT BACKGROUNDCiner Wyoming, LLC (formerly OCI Wyoming, LLC) owns and operates the Big Island Mine facility near Green River, Wyoming. This underground trona mine has produced soda ash since 1962. The Greater Green River Basin covers much of southwestern Wyoming and extends into northeastern Utah and northwestern Colorado. The Ciner facility is located in the Green River Basin, which is part of the Wyoming Basin physiographic province. The Green River runs to the west and the south of the Ciner facility.Beginning in the early 1990s, Ciner primarily disposed tailings underground in mined-out panels. However, in recent years, underground storage has become limited and some disposal has transitioned to the ground surface. Long-term planning revealed a need to expand Ciner’s surface tailings disposal capabilities. Pond 2, a previously permitted disposal area, was identified as the most viable location for a storage facility. The Pond 2 site is directly north of the Ciner plant facilities, northwest of the active Upper Delta tailings storage facility, and northeast of the Green River (Fig 1)."

Jan 1, 2016

By Akshay Sakhuja, M. S. Karthika, R. Vignesh

"The bridge across River Mandovi in Goa is a cable stay bridge structure proposed parallel, along existing bridges for regulation and reduction of vehicular traffic; the entire bridge structure is supported on pile foundation socketed in rock. This paper describes drilling related issue encountered during execution of pile where bed rock varies considerably from factual geotechnical investigation, which in turn affected the productivity of bored piles socketed in rock then chiseling is advocated for rock socketing with limited number of blows based on penetration resistance of rock encountered or equivalent energy principle to increase the productivity and also to avoid excess chiseling which otherwise would have fractured the rock mass below and around the pile tip resulting in increased settlement of pile subjected to design load. Contractor decision on socket length have been taken without compromising either quality or productivity; the paper presents various procedures and the equipment involved for installation of pile in rock along with the conclusion related to termination of pile in rock and also the lessons learned in process.INTRODUCTIONPile foundations are generally used to transfer heavy loads in deeper bearing stratum if the soil immediately beneath the base of the foundation does not have sufficient capacity. The bridge across River Mandovi, Goa is in its construction phase as a part of the development plan of Goa State Infrastructure Development Corporation Ltd (GSIDC). The project was awarded to M/s. L&T Construction, Heavy Civil Infrastructure; subsequently the geotechnical investigation was awarded to M/s L&T Geostructures.The client has specified the foundation of the bridge as rock-socketed. Rock socketing is generally done to achieve higher bearing pressure through concrete-rock shear interface which many building codes permit. The design and construction of rock socketed pile foundation entails a detailed analysis and judgement on the superstructure loads, predominant geological conditions as well as ground water levels. The termination of pile is normally based on thumb rule of half to three times the pile diameter into the rock. Quite often the criteria is based on chisel penetration rate (Gandhi,1990) In fact, this is the key factor to consider appropriate and economical depth of embedment of pile into rock stratum which necessitates enormous understanding on the type and quality of rock strata encountered which may significantly influence the selection of suitable rotary rig for pile installation. Such criteria are site specific and also applicable for the set of equipment used for the particular project."

Jan 1, 2015

By Abolfazl Eslami, Samieh Rezazadeh

"Semi-Deep skirted foundations are considered to be a viable option for a variety of onshore and offshore applications. It is necessary to determine appropriate foundation configurations that allow loads to be transferred safely to the surrounding soil. For this purpose the bearing capacity and stability analyses subjected to combined vertical, horizontal and moment loadings must be found. In this paper the vertical undrained bearing capacity is estimated via finite element analyses. The circular skirted foundations with different geometries considering embedment depth (embedment ratio between 0-2) and size effects (diameter equals to 5, 10, and 20) have been studied. Stress field, kinematic mechanism accompanying failure and bearing capacity factors for total, end and shaft resistance in semi-deep foundations with various embedment ratios are investigated. Furthermore, two probable mechanisms i.e. internal flow and soil plug for estimating foundation capacity for design purpose in practice have been assessed. Comparisons with different research works including conventional methods, upper and lower bound approaches, and finite element analyses have indicated that the conventional methods underestimate the bearing capacity due to ignoring the significant role of shaft resistance. Determining appropriate economic foundation configurations to transfer loads safely to the surrounding soil is a major issue in geotechnical engineering. Shape and dimension of foundations, embedment depth, soil characteristics and applied loading, all affect the foundation performance. Recent studies have shown that for foundations with large breadth and of D/B between 1 to 4, kinematic mechanisms and failure modes are different from the two main types of foundation (i.e. shallow and deep). Therefore, D/B factor must not be considered as the only factor for defining foundation type. ""Semi-Deep foundations"" are another foundation category distinguished based on their performance. This relatively new concept is becoming increasingly an optimum alternative for shallow and deep foundations to support structures especially in accessible depth. As illustrated in ""Fig. 1"", different types of semi-deep foundations consist of:"

Jan 1, 2017