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By Frank Haehnig

Ground freezing is a technique which is used more and more in tunnelling under complex ground conditions. This paper will present three case studies which highlight different aspects of the ground freezing technique when applied in urban environment. The first project is the City-Tunnel in Leipzig, Germany, which is being built beneath the central station and which is the largest ground freezing project currently under construction in Germany. The second case study is part of the North-South-Line project in Amsterdam, Netherlands where ground freezing will be carried out to al-low the TBM drive through old wooden foundation piles. The freeze tubes for this project will be driven using Horizontal Directional Drilling (HDD). The last project is the Hallandsas Tunnel Sweden where the ground freezing equipment has to be installed against high water pressure. The paper illustrates that ground freezing can be implemented in difficult ground conditions such as soft ground, highly fractured rock and high water pressure. The case studies highlight the importance of good workmanship. With the increasing numbers of large tunnels being constructed in difficult ground conditions the paper concludes that the complex case studies presented will be-come more representative for future tunnel projects in urban environments.

Jan 1, 2008

By Gregory T. Ziegler

A complex soil profile and high water table, together with a below-grade active subway tunnel, an above-ground elevated railway line, and the heavily travelled Northern Boulevard all passing above the tunnel alignment, combined to make mining of New York?s Northern Boulevard Crossing what is widely considered to be the most challenging portion of the multi-billion-dollar East Side Access project. The Northern Boulevard Crossing is a vital link in this project which, when completed, will connect the Long Island Railroad to Grand Central Terminal in Manhattan. How the sequential excavation method (SEM) tunneling was successfully accomplished, despite the obstacles, was a textbook exercise in practical innovation coupled with close cooperation between the owner, the construction manager, Hatch Mott MacDonald, the designer, Parsons Brinckerhoff, the contractor, Schiavone-Kiewit, and spe-cialty geotechnical contractor, Moretrench.

Sep 1, 2013

By Theodore Budd, Joseph A. Sopko

Ground freezing was selected to provide excavation support and ground water control for the construction of a 457 cm diameter tunnel between two underground structures for a major sewer project in Milwaukee, Wisconsin. Initial plans called for installing horizontal refrigeration pipes around the perimeter of the tunnel. Due to the possibility of difficult conditions associated with horizontal drilling, the contractor elected to drill inclined pipes from the surface. The surface location, however, crossed a city thoroughfare with an extensive system of buried utilities. This paper discusses drilling techniques and utility protection, as well as tunneling methods and production.

Jan 1, 1991

By Shawn P. Coughlin, Michael A. Schimmenti, Juan Leonardo Tello del Pino

"PROJECT OVERVIEWThe Sistema de Potabilización Área Norte project (Northern Area Purification System) was a major expansion of the potable water system in Buenos Aires Province, Argentina. The aim of the project was to transport and purify raw water from the Paraná River to provide potable water for five communities in the northern part of the province, benefitting up to two million inhabitants. The project was constructed by a joint venture of four South American contractors (“the JV”), and consisted of the following key components:• Treatment Plant: A 16 hectare area was cleared for the construction of a treatment plant to purify 900,000 m3/day of raw water from the Paraná River and distribute it to the surrounding communities.• Bored Tunnel: Nearly 15 km of 3.6 m inner diameter tunnel, ranging from 18 to 22 m below grade, was bored with two EPB tunnel boring machines to draw the raw water from the river. The TBMs started from a central launch shaft and proceeded in opposite directions: Cristina advanced northbound to the Paraná River Intake System, and Liliana advanced southbound to the new treatment plant.• Access & Ventilation Shafts: Five access shafts and eight ventilation shafts were installed along the length of the tunnel. The access shafts were designed to provide entry points for inspection and maintenance of the final tunnel. The five shafts consisted of: one central launch shaft in the middle of the tunnel alignment, one retrieval shaft at each end of the tunnel (Intake and Treatment Plant, respectively), and two intermediate shafts. The intermediate shafts were installed before the TBM passed, with a final liner to be installed afterwards. Access Shaft 3, the intermediate shaft located between the launch shaft and the treatment plant, experienced persistent leaks during initial excavation attempts."

Jan 1, 2016

By Shawn P. Coughlin, Michael A. Schimmenti, Juan Leonardo Tello del Pino

"The Sistema de Potabilización Área Norte project (Northern Area Purification System) was a major expansion of the potable water system in Buenos Aires Province, Argentina. The aim of the project was to transport and purify raw water from the Paraná River to provide potable water for five communities in the northern part of the province, benefitting up to two million people. The project was constructed by a joint venture (JV) of four South American contractors and consisted of the following key components:• Treatment plant: A 16-ha (39-acre) area was cleared for the construction of a treatment plant to purify 900,000 m3/day (1.2 million cu ft/d) of raw water from the Paraná River and distribute it to the surrounding communities.• Bored tunnel: Nearly 15 km (9 miles) of 3.6 m (12 ft) inner diameter tunnel, ranging from 18 to 22 m (59 ft to 72 ft) below grade, was bored with two earth pressure balance (EPB) tunnel boring machines (TBM) to draw the raw water from the river. The TBMs started from a central launch shaft and proceeded in opposite directions. Cristina advanced northbound to the Paraná River Intake System, and Liliana advanced southbound to the new treatment plant.• Access and ventilation shafts: Five access shafts and eight ventilation shafts were installed along the length of the tunnel. The access shafts were designed to provide entry points for inspection and maintenance of the final tunnel. The five shafts consisted of one central launch shaft in the middle of the tunnel alignment, one retrieval shaft at each end of the tunnel (intake and treatment plant, respectively) and two intermediate shafts. The intermediate shafts were installed before the TBM passed, with a final liner to be installedafterward."

Sep 1, 2016

By Paul C. Schmall, Lucian P. Spiteri, Arthur B. Corwin

Moving groundwater is generally recognized as the most adversarial condition for ground freezing. Moving groundwater can occur due to natural or man-induced groundwater flow, but either way may result in freeze formation difficulties. History has shown that if the condition goes undetected, catastrophic failure of the frozen shaft or excavation can occur. The success of ground freezing under potentially flowing groundwater conditions depends on an evaluation of the likelihood for this condition; an accurate and early diagnosis, with a careful evaluation of freeze pipe temperatures and piezometer water levels; and timely reaction to mitigate the possible delays. Successful remedial measures have included the reduction of ground permeability by modifying the soil properties between the freeze pipes with various kinds of grouting, or increasing the freezing effect by adding freeze pipes and/or the use of liquid nitrogen as the freezing agent.

Jan 1, 2007

By Joseph Sopko, Xavier Lacourse-Dontigny

For the REM (Réseau Express Métropolitain) project, a 2500 m tunnel was built using a tunnel boring machine (TBM) under the Montreal Pierre Elliott Trudeau Airport (ADM). Although the geology under the Montreal Airport (ADM) would have been suitable for an excavation with a hard rock machine, the rst section reuired an earth pressure balance (EPB) TBM due to the soft soil located under wetlands. After excavating 280 m, the TBM was blocked in a transition zone of unconsolidated, water-bearing soils directly above the underlying bedrock. A free air intervention was not possible due to these geological conditions. After several failed attempts to create a slurry cake for hyperbaric interventions, a ground freezing system was designed and implemented, incorporating angled pipes drilled from outside the wetlands to directly in front of the cutterhead. This paper discusses the engineering reuired to form a frozen, water-tight zone in front of the cutterhead using liuid nitrogen. It also describes the complex method of replacing the disc cutters while holding the ground freezing system active in a manner protecting the health and safety of the workers.

Jun 23, 2024

By Joseph A. Sopko

There has been a trend in recent years in performing the initial formation freezing using liquid nitrogen (LIN) and then converting the system to circulating refrigerated brine. While proponents of this method state it decreases freezing time, it can also be considered an alternative to inadequate refrigeration capacity. This method was used on several small projects in the 1980s. Problems such as broken pipes, frozen brine, and unsafe work conditions caused contractors to re-think the method. This paper discusses these problems and also presents work schedules showing no schedule reduction. In fact, this method can lead to longer time as well as significantly higher costs. BACKGROUND Ground freezing as a method to provide groundwater control and temporary earth support for excavations is completed using a relatively simple process: drilling and installing refrigeration pipes around the perimeter of the excavation and introducing a coolant into these pipes. The coolant extracts heat from the ground, converting the pore water to ice and forming a strong, impermeable material. A typical ground freezing system is illustrated in Fig. 1. SYSTEMS There are two basic types of coolant systems: circulating and direct expansion. The circulating coolant system is made of two separate, closed systems. The medium circulating is the secondary coolant. It is cooled at a central refrigeration plant, circulated through the pipes, and warms as it extracts heat from the ground. It then circulates back to the plant where it is cooled. This coolant is chilled in a heat exchanger by the primary refrigeration system where a compressor system is charged with a refrigeration gas. The heat is ultimately extracted from the ground and expelled into the atmosphere by an evaporative condenser. Secondary coolants are usually a brine or glycol chemical while the primary refrigeration gas is anhydrous ammonia or another commercially available gas.

Jan 1, 2019

By A. Sacit Saydam

"Induced polarization/resistivity and magnetometer surveys have been carried out over the Casmo molybdenite deposit in mountainous terrain of northern British Columbia. Molybdenite occurs in quartz-bearing fractures with or without pyrite along a zone of hydrothermal alteration and intense fracturing, believed to be a northerly dipping fault zone, within medium-grained equigranular and porphyritic quartz monzonite.The molybdenite-bearing zone is characterized by a significant resistivity low, a metal factor high and a subtle IP low flanked by highs outside the mineralized area. Magnetic trends, indicated by a magnetometer survey, generally parallel the zone and strike direction of the different intrusive phases, and have been helpful in delineating contacts and faults in the area.IntroductionThe Casmo molybdenite deposit is 6 km southwest of the asbestos mining town of Cassiar in northern British Columbia, at an elevation of 1,550 metres. Molybdenite was first discovered during the early 1950s and the first important exploration work was done in 1964. Between 1964 and 1971, about 25,000 feet of drilling was done by various operators, as a result of which 33.7 million tons of molybdenite ore was drill indicated at a grade of 0.123%. In 1979, Shell Canada Resources entered into an option agreement with the former operator, New Jersey Zinc Corporation. Shell completed 27,000 feet of diamond drilling between 1979 and 1980 and ha s reported 75 million tonnes of drill-indicated ore with an average grade of 0.13% MoS2• This paper is a case history of IP I resistivity and magnetometer surveys done over the Casmo deposit during 1979 and 1980."

Jan 1, 1983

By N. Saracoglu, R. H. Wallis, J. E. Betz, F. L. Jagodits, B. R. Krause

"Geophysical test surveys were conducted with various methods (EM, lP, gravity and magnetic) over the McClean uranium deposits of the Canadian Oxy- lnco Joint Venture. The result s were assessed to judge the contribution each method might make toward further discoveries of graphite-associated uranium occurrences.The best drill targets have proven to be discontinuities in graphitic conductors and locations where the tatter are intersected by fracture zones in the Athabasca. The tests demonstrated that the preferred combination of geophysical survey s is horizontal loop EM to locate graphitic conductors in the basement and VLF-EM to locate the fractures.IntroductionThe discoveries of the McClean North and South uranium deposit s (Fig. 1) are essentially geophysical successes resulting from drilling MaxMin delineations of INPUT airborne electromagnetic responses (Saracoglu et al., 1983). After the initial discovery in 1979, various geophysical methods, techniques and instruments were employed to test their effectiveness in this environment and to guide exploration for other deposit s of a similar nature in the remainder of the 260 km2 property.The McClean uranium deposits lie below 150 m to 180 m of overburden and Athabasca Group. Radioactive signatures might be expected; however, the Athabasca Group acts as a barrier to radioactive emanations. Fortunately, the uranium mineralization is associated with graphite in the crystalline basement. Prior drilling of ground electromagnetic anomalies confirmed that EM surveys could locate and out line basement graphitic conductors. However, as there were many anomalies, most of which could not reasonably be expected to be associated with uranium , there was need to identify additional parameters, related to mineralization, which could be detected geophysically and used to narrow the search."

Jan 1, 1986

By Mike Power

Geophysical techniques have played a pivotal role in northern kimberlite exploration since the initial discovery at Point Lake in 1991. In the Slave Craton and surrounding regions, there are definite contrasts in physical properties between kimberlite intrusions and surrounding bedrock. Kimberlite commonly displays higher magnetic susceptibility, distinctive remnant magnetism, low electrical resistivity and lower density than surrounding rocks. In addition, the distinctive geometry of kimberlite pipes is reflected in geophysical responses which further facilitates target discrimination. There has been an evolution in geophysical exploration strategies over the past 12 years. Helicopter total magnetic field and electromagnetic (HEM) surveys have proven to the most cost-effective means of conducting first pass investigations in prospective areas. During the early 1990's, total magnetic field and frequency domain electromagnetic surveys were virtually the sole techniques employed during follow-up surveys. Inevitably, the initially high rates of kimberlite discovery declined in the areas surrounding the original finds. Marginal magnetic and EM anomalies were all that remained to be tested and this spurred interest in the improvement of existing interpretation algorithms and in the application of additional complementary techniques to reduce the exploration risk. Gravity has become a popular third survey following the deployment of the Falcon (TM) airborne gravity gradiometer system by BHP Billiton in 1999 and improvements in ground techniques. Ground penetrating radar (GPR) has proven to be particularly useful in delineating kimberlite pipes following drill discovery and in exploring for kimberlite dykes in settings where indicator mineral trains indicate such targets are likely. Seismic methods have been tested for both reconnaissance and delineation but remain underemployed. Given the high cost of drilling in the North and the proven success of geophysical techniques in reducing exploration risk, it is likely that an increasingly diverse range of geophysical techniques and innovative interpretation techniques will continue to be applied in kimberlite exploration.

May 1, 2003

By F. J. Hogan

In early 1982 Atlantic Cement Company, a wholly-owned subsidiary of Newmont Mining Corp. will come on line with a new water granulating grinding facility at Sparrows Point, Maryland to produce 800, 000 tons a year of separately ground granulated blast-furnace slag. The process and product will be unique to the United States. This paper will review some initial investigations undertaken to evaluate the cementitious properties of granulated slag. The effect of slag fineness on strength development is discussed and data is presented showing a relationship between glass content and hydraulicity and grindability of slag.

Jan 1, 1982

By E. Douglas, V. M. Malhotra

"This report presents the results of a laboratory study undertaken to evaluate ground granulated blast-furnace slag from Algoma Steel Corporation, as a replacement for Portland cement in cemented mine backfill. The evaluation was based on the results of compressive strength tests performed on cylinders cast from mixtures made with a granulated blast-furnace slag and tailings from four different mines in the Sudbury basin. Various percent¬ages of slags and various binder to tailings ratios were used.Tests results show that, in terms of compressive strength, the slag performs as well or better than Portland cement as the binding agent in cemented mine backfill. Lime was found to be a poten¬tially good activator for ground granulated slag in mine backfill applications.A field test was conducted at one of the mines, consisting of placing a mixture of 95.5% ground granulated slag and 0.5% lime into a stope, and inspecting the floor slab as it hardened. The slag performed as expected, considering the backfill mixture proportions used and the preparation of the test site."

Jan 1, 1989

By Noreen Tarac, Pablo Forgoso, Philipp Schober

A multiple use storage facility building is being developed in the Philippines on a peninsula that was reclaimed in the 1990s without any soil treatment. The subsoil now consists of loose to medium dense silty sand underlain by a soft to medium stiff clay. A liquefaction assessment by analytical methods have shown that the loose to medium dense silty sand yields a high potential for liquefaction and lateral spreading during pthe design level seismic event. To mitigate the risk of liquefaction and lateral spreading, as well as assure the slope stability of the shoreline, a solution utilizing a combination of ground improvement techniques by means of a Mixed-In-Place (MIPTM) Lattice Grid Wall and Stone Columns was developed and successfully executed. For the detailed seismic design, a Finite Element 3D analysis was undertaken to simulate static and dynamic actions on the buttress wall. The liquefaction assessment and settlement calculation were carried out based on analytical design approaches. For the execution of the Lattice Grid Wall, the Mixed-In-Place (MIPTM) method developed by BAUER Spezialtiefbau GmbH was applied. The stone columns were installed using the Wet Top Feed method.

Sep 8, 2021

By Peter White

A bridge reconstruction project involved driving pipe piles for the new foundations. Disturbances within soil layers at depth caused sinkholes to open up within the construction site. After a near fatal accident, the pile driving installations were suspended. The solution involved ground im­provement through cement grouting with sleeve pipes and special grout additives to minimize migration of cement grout.

Jan 1, 1997

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 Tatiana Tronda

"The territory of Belarus is characterized by nonhomogeneous ground conditions. In some cases soft ground layers can reach tens of meters in depth. Application of piles and other conventional foundations is rather difficult and expensive in such complicated conditions. Alternatively for the first time dry concrete columns were applied to improve the saturated soft soils at two sites. As there is no design methods for calculation of bases improved by dry concrete columns static penetration and static load tests were carried out to check the bases on availability. Considerable increase of toe resistance and Young modulus was achieved for all types of soil. Practical application, technology and test results are described in the paper. According to comparative calculations the cost of foundations on the base improved by dry concrete columns can be 32-75% lower than the cost of conventional pile foundations depending on ground conditions.INTRODUCTIONPile foundations, sand cushions or dewatering are usually applied in complicated ground conditions which are caused by presence of saturated soft soils. If the depth of soft soils reaches 20 m or more, conventional foundations have limited application, high labor and construction cost. A rational solution in such conditions is a ground improvement of upper soft soils. It allows the loads to be transferred on upper ground layers and the stresses to be dissipated considerably before reaching underlying soft ground layers.One of the effective ground improvement methods for saturated soft soils is the reinforcing by dry concrete columns (Fig. 1). The method allows saturated soft soils to be compacted and be drained at the same time. As a result strength and deformation characteristics of natural soils improve (Tronda 2013, ?????? 2014).Unfortunately, there is no design and computing methods for the ground improvement by means of dry concrete columns. However, at present the methods are under development on the basis of theoretical and experimental researches.TECHNOLOGYThe dry concrete columns are fulfilled in pressed wells according to technology of vibrostamped piles. Wells are pressed by vibratory hammer with the closed ended casing (Fig. 2) that provides compaction of surrounding soft soils. Then the casing is filled with dry concrete mix (Fig. 3). The casing end remains on the design depth and the casing is removed by vibratory hammer. The removing of the casing with vibration enables compaction of dry concrete mix inside the well. Dry concrete mix drains surrounding saturated soft soils improving its properties and the compaction speeds up the consolidation process. Over time the dry concrete columns fasten absorbing water from surrounding saturated soft soils that is need for hydration of cement (Fig. 4, 5)."

Jan 1, 2016

By J. Racinais, P. Vincent

"In September 2011, Menard Oceania (MO) was engaged by Mac Mahon John Holland Joint Venture (MJHJV) to provide ground improvement solution for the $34bn Ichthys LNG development. With close to 400,000m2 of mangrove swampland set to be reclaimed and improved, this project was a great opportunity to showcase the technical, commercial and environmental benefits that Dynamic Replacement (DR) ground Improvement technique can provide. The ground improvement works involved complete design and construction for the Ichthys LNG site located at Blaydin Point on a low lying peninsula in Darwin Harbour. Dynamic replacement and stone columns technique were selected to treat intertidal mangrove mud to achieve required bearing strength, stability and limit settlement to an acceptable levels. The site is underlain by a 3m to 5m thick layer of highly organic mangrove muds with very soft shear strength ranging from 0kPa to 12kPa at depth. The site is exposed to daily sea water level tidal variations of up to 8m, which created significant constructability constraints and slope instability risks. This paper presents the design philosophy, the process involved in the selection of the construction methods, the site constraints encountered during the works and a review of the results achieved, quality control and post constructions performance.INTRODUCTIONInpex Browse, Ltd (Inpex) and its partner Total are developing the Ichthys gas field to pipe gas to onshore facilities at Blaydin Point on the south side of East Arm in Darwin Harbour. The proposed LNG plant consists of gas receiving facilities, 2 x 4.2Mtpa nominal capacity LNG trains, LPG and condensate production facilities, product storage and export facilities, a module offload facility (MOF), a flare pad (FP) and associated off plot facilities.The proposed on-shore facilities are located on extremely soft intertidal mangrove muds, therefore an appropriate ground improvement was required to achieve required strength and stability of site works and limit long term settlement to an acceptable level.Various ground improvement techniques were studied to select the most suitable for the ground conditions and site constraints encountered at the Blaydin point site. Dynamic replacement technique was selected for onshore section to improve soft mangrove mud to depths of 5.5m and Stone Columns (SC) technique was selected for MOF off-shore section to improve intertidal deposits to a depth of 2.5m.This paper presents DR design and construction works performed between December 2012 and August 2013 at Flare Pad Area."

Jan 1, 1900

By Alp Gokalp

The aim of this article is to present an application of jet grouting technique in stiff clays for foundations of the natural gas combined cycle power plant, under construction in Aliaga, Turkey. The plant site is in the Aegean coastal region and 60 km north of Izmir. The foundation soil is composed of quaternary alluviums on top and tuff base rock. The thickness of the alluvium varies between 16 m to 30 m. Groundwater was observed 2.5 m below the ground level. At the design stage, settlement analyses were carried out for the various buildings and facilities in the power plant. Based on the analyses, it was predicted that total and differential settlements are not tolerable, thus jet grouting is implemented as a ground improvement under the majority of the foundations of the power plant. This paper also describes the selection of jet grouting technique, application type and details of the process parameters such as injection pressure, number and size of nozzles, lifting and rotation speeds. Prior to the commencement of the jet grouting works, a number of preliminary parameter tests and preliminary pull-out tests were carried out throughout the site in order to define and verify the jet grouting process parameters to achieve the required diameter of 600 mm and minimum jet grout strength of 3.2 MPa. Moreover as part of the comprehensive quality control and quality assurance program pursued in the project, a number of tests; such as continuous coring, integrity testing, installation of confirmatory jet grout columns, were carried out during the production of jet grout columns.

Jan 1, 2002

By Georg Breitsprecher

The technique of Stabilising Columns (product names are for example "Stabilisierungssaulen" (STS) or "Coplan Stabilisierungs-verfahren" (CSV)) is gradually becoming well accepted for ground improvement. The installation, dimensioning and quality control are standardized by DGGT (German Association for Geotechnique), working committee 2.8, of which until now only part one exists for dry columns. This paper describes the installation and testing of stabilising columns for a ground improvement project. To achieve comparable results in testing both ready mixed concrete and dry binder had been used for production.

Jan 1, 2006