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By Bernardo J. Jiménez Vega, Edy L. T. Montalvan

During the last phase of the Circunvalacion Norte project in San Jose, Costa Rica, preliminary designs for an underpass structure of over 16 km (10 miles) considered drilled shafts as an earth retaining system. Since the project’s execution was delayed and close to the deadline, it was necessary to optimize this structure, with the drilled shafts being the most critical aspect. The key element in order to obtain an improved design was characterizing the job site with a specific site study for seismic demand, and the use of advanced numerical modelling, considering soil-structure interaction. The site investigation comprised the CPT, PMT, MASW geophysical tests, deep exploration drilling, and triaxial compression tests. The terrain was modeled using an advanced constitutive model with hardening plasticity calibrated from the triaxial tests. Plaxis software was used to calibrate the seismic model for the terrain and for the dynamic analysis. Two conditions were considered for the retaining structure: free-head and fixed head. A parametric study with drilled shafts of 1.0 m (3.3 ft) and 1.2 m (3.9 ft) in diameter, and center-to-center spacing of 1.3 m (4.3 ft) and 3.0 m (9.8 ft) was conducted in order to obtain an optimized structure. For each condition of the drilled shaft wall, the computed deformations were compared for two spectrum designs: site-specific spectrum and seismic code generic spectrum. Finally, a dynamic analysis was performed to check the performance of the drilled shafts with optimized spacing using a control earthquake. Based upon seismic performance curves, the analysis showed the possibility of greater spacing for the drilled shafts compared to the original design, obtaining a 32% reduction in the total length of the drilled shafts in the project.

Oct 1, 2022

"The Metropolitan St. Louis Sewer District (MSD) in Missouri, the country’s fourth largest sewer system, is upgrading its storm and wastewater infrastructure in a 23-yearlong, $4.7 billion initiative called “Project Clear.” Historically, during times of intense precipitation, the current sewer system becomes overwhelmed. The primary goals of this project are to improve water quality and to alleviate many wastewater concerns in the St. Louis region by planning, designing and building community rainscaping, system improvements and an ambitious program of maintenance and repair.Part of the system renovation has focused on constructing underground tunnels for storm water storage, permitting controlled drainage of runoff, and preventing overflows into rivers and streams. Construction plans for these storage tunnels called for eight vertical intake and ventilation shafts to be bored from the ground surface. These shafts will then be intercepted in the bedrock at a depth of about 150 ft (45.7 m) during the excavation of the 3,000 ft (915 m) long underground tunnel that will be about 28 ft (8.5 m) in diameter. According to John Deeken , a geotechnical engineer with Black & Veatch Corp. and construction manager for the Maline Creek project, the drilling and blasting technique for creating the shafts was ruled out because the project was located in a residential neighborhood. “We could have used rock coring or a cutter head, but the drop shaft for this project is constructed within 10 ft (3.05 m) of an existing 108 in (274 cm) diameter sewer main,” Deeken said. “We had to take precautions to avoid damage to it.”A primary planning mandate of all MSD Project Clear phases requires minimized impact on traffic and residents. The canister drilling method enabled work to be confined to the median of a residential boulevard running perpendicular to the side street without detouring traffic. In addition, canister drilling offered a highly-precise means to create the shafts, leaving a smooth-sided borehole, right on target. Ground conditions in this 132 in (3.35 m) diameter intake shaft were wet due to the high groundwater levels and close proximity to the Mississippi River. “They’ve been finding shale in 2 to 6 ft (0.6 to 1.8 m) layers between weathered layers of Mississippian limestone,” said Dan Spiecher, technician at Center Rock (CRI). “The 2 ft (0.6 m) layers we can punch through. The 6 ft (1.8 m) layers slow us down.”"

Jan 1, 2017

By Mohamed A. Eliwah

This paper deals with the determination of hydraulic conductivity of the coastal coralline limestone aquifer of Jeddah, Saudi Arabia. This coastal area has witnessed urban development and establishment of towers which requires deep foundations, excavation and dewatering of huge quantities of unconfined groundwater. It is occupied with successive layers of soft detrital and consolidated massive cavernous coralline limestone of the Quaternary age. These layers are encountered at a depth of 1.5m and extend for more than 100m. Hydraulic conductivity values were obtained by analyzing the pumping tests data under steady and transient state conditions. Hydraulic conductivity values help in selecting the proper and safe dewatering system, as well as determination of discharge rates and quantities of groundwater to be withdrawn. Test results obtained from two surveyed sites showed that the values of hydraulic conductivity are greatly variable. It ranges between 118.1 and 1559.6 m/day at the first site, whereas at the second one it ranges between 94.6 and 350 m/day. These high values are attributed to the cavernous nature of the water-bearing formation. Jeddah city could be divided into three different dewatering zones extending from north to south parallel to the coast line. Well point dewatering system could be applied in the first zone while ditches and sumps are the most suitable dewatering method in the second and third zones. Dewatering using deep wells in such highly permeable formation will require withdrawal of huge quantities of water which will be accompanied by washing out fine sediment filling the cavities in the surrounding areas. This will badly affect the nearby buildings through settlement, crakes and other structural damages. Therefore, construction of grouting plug/blanket with thickness of 3.0 m at a depth of 20.0 m is recommended. This depth will be enough to support the plug against the hydrostatic pressure. Moreover, it is highly recommended to transfer the site into closed box, by using diaphragm walls or secant bored piles.

By Jewels Stover, Charles A. Luxford

Oklahoma City is undergoing a replacement program for an existing 66in (1.675m) water pipeline that conveys raw water from Atoka Reservoir to the City. This pipeline currently crosses the Canadian River on elevated piers and is subject to flood hazards. To replace the existing pipeline and mitigate flood damage concerns, two parallel microtunnels will be constructed below the river channel. Access is from construction shafts located near the midpoint of the tunnels; opposing drives are launched from each shaft. This geometry dictated shafts of significant depth – exceeding 120 ft. (37m). To accommodate the casing pipe segments and microtunneling machines, a minimum shaft diameter of approximately 34 ft. (10.4m) was required. Due to the difficult geologic setting, a reinforced secant pile compression ring is specified by contract in the top 70 ft. (21.3m) of these construction shafts to provide a very low permeability support system.

Sep 8, 2021

By Marco Fellin, Van E. Komurka

Significant cost and construction benefits were obtained from performing a bi-directional static load test prior to construction on the Russell Street Bridge Replacement project in Missoula, Montana. The project utilized 24 drilled shafts to support two three-span bridges across the Clark Fork River. A bi-directional static load test (“BDSLT”) was performed on a large-diameter production shaft to demonstrate construction methods and confirm design assumptions. Subsurface conditions consisted of gravel with sand to a depth of 20 feet (6.1 m), underlain by gravel with sand, silt, cobbles, and occasional boulders. The test shaft had a nominal diameter of 5.9 feet (1.8 m), and an embedded length of 75.5 feet (23.0 m). The geotechnical engineer of record and the BDSLT test engineer collaborated to optimize the BDSLT jack assembly location within the test shaft, determine appropriate instrumentation locations, and plan the test protocol. The maximum applied test load was 10,707 kips (47.6 kN). Significant benefits were obtained from performing the BDSLT test, including 1) reducing each production shaft’s length by using a higher LRFD resistance factor allowed by having performed the testing, 2) using test-determined unit shaft resistances to evaluate and accept two production shafts that may have otherwise required remediation, and 3) providing the Montana Department of Transportation (and other designers) with increased presumptive unit resistance values in the gravel/cobble/boulder deposits. PROJECT DESCRIPTION The project was constructed in Missoula, Montana for the Montana Department of Transportation (“MDT”). The original bridge was approximately 60 years old, and consisted of a two-lane, 420-foot-long (128-m), four-span, riveted steel plate girder design spanning the Clark Fork River. The bridge was due for replacement owing to its deteriorated state, and the need for increased traffic volume capability afforded by a four-lane structure. HDR was the structural engineer. The preferred bridge alternate was a 459-foot- long (140-m), three-span, welded steel plate girder design. The new bridge was designed to meet current standards in accordance with MDT bridge design and AASHTO LRFD criteria. The new bridge was constructed in phases to keep traffic open during construction.

Jan 1, 2019

By Greg Nutson, Jeremy Butkovich, Bill Perkins, Hollie Ellis, Paul Bott

"Dynamic soil-structure interaction (DSSI) analyses are becoming more common in bridge designs, especially in seismically active areas. Because of its proximity to two active fault zones, the Evergreen Point west approach bridge replacement will be base isolated, and will be designed using DSSI. The project team completed two independent bridge designs to satisfy peer review requirements. The designs required substantial characterization of the soil dynamic behavior using both laboratory and in-situ testing. The analyses made use of earthquake time histories spectrally matched to conditional mean spectra. This led to reduced, and more realistic seismic demands on the structure, compared to conventional uniform hazard spectrum matching. The bridge analyses suggest that the preliminary bridge design is relatively conservative. This will allow the design team to potentially reduce shaft/column diameters and reinforcement. The design team estimates that the dynamic analysis design could represent a net savings of around $60 to $90 million compared to a conventional design.INTRODUCTIONThe Evergreen Point Bridge conveys State Route (SR) 520 2.6 miles (4.2 kilometers [km]) from Seattle to Medina across Lake Washington. The bridge is located in a seismically active area, and the Washington State Department of Transportation (WSDOT) has determined that the western half of the 1960s-era bridge (the “west approach”) is vulnerable to earthquake damage. WSDOT has begun preliminary design to replace the west approach bridge.The west approach extends about 6,100 feet (1,900 meters [m]) east from Seattle’s Montlake neighborhood, over Union Bay and Foster Island, then into Lake Washington proper (Figure 1). Approximately 5,600 feet (1,700 m) of the replacement bridge would be constructed over water. Subsurface conditions along the bridge alignment consist of 5 to 80 feet (2 to 24 m) of very soft peat and clay, over very dense/hard sand and clay. Multiple pile supported columns support the existing bridge. The new bridge would be supported by 8- to 10- foot-diameter (2.4 to 3.0 m) drilled shafts that extend about 50 feet (15 m) into the underlying very dense/hard soil. To reduce seismic demands on the bridge superstructure, WSDOT has decided to incorporate a base-isolation system into the bridge design."

Jan 1, 2017

By Liu Run, Jia Zhao-lin, Yan Shu-wang

"Piles with diameter larger than 2m in engineering can be defined as large diameter pile, and piles used for oil platform foundation in Bohai Gulf, are usually over 100m long and 2m in diameter. Such long piles have to be manufactured by segments before installation, because of transformation and hoisting difficulties. The segments of the pile are assembled by welding during installation one to another. Normally, assembling two pile segments takes one day or even a longer time, which mainly depends on construction conditions. After pile segment assembling, it proves to be difficult to restart the successive penetration. The mechanism of pile refusal is discussed and the process of driving a segmented pile is simulated with a finite element program. The calculating results show that, when the stick-up stability was satisfied, increasing the length of the last segment of the pile and assembling the pile segments when the pile tip penetrates into a clay layer could greatly ease the difficulty of driving the pile. Furthermore, cutting down the pile extension time is also one of the most effective measures to minimize the refusal risk.1. InstructionIn recent years, more and more oil platforms with six or eight legs have been adopted in Bohai Gulf, China. The leg piles with diameters of 2m or more have to be driven to about 100m below the sea bed. Such long piles have to be manufactured by segments before installation, because of transportation and hoisting difficulties. The segments of the pile will be assembled during installation, in which a successive segment will be attached to a formerly penetrated one by welding (Fig.1). The assembling work often takes one day or even a longer time."

Jan 1, 2014

By Xuhui

Pile foundations are underground projects which are carried out under complicated site conditions, so it is difficult to summarize their characteristic patterns from the everchanging practical pile foundations. In combination with theories, the paper analyses the effects of sound reinforced concrete piles and various types of defective piles on the propagations of stress waves. Through testing on prototype pile models, by use of the transient dynamic method and comprehensive analysis in both time domain and frequency domain, their reflection characteristics and patterns are acquired. In addition, discussions are carried out in combination with some real projects. Our model tests include comparison of large scale pile models of 20X20cm in cross section, 5. 0m in length respectively in air, standard sand, and natural stratum; prototype model tests of digged piles of 0. 7-1. 2m in diameter, and 18m, 30m in length; prototype model tests of bored piles of 0. 6m, 0. 8m in diameter, 12-20m in length. Test results show that no matter in air or buried in medium, the intrinsic characteristics of sound piles and various types of defective piles are fixed. In their time domain waveforms and spectral diagrams, obvious regularity are shown, which proves that the relations between the pile natures and their dynamic responses are fixed, which provide basis for correct judgement of pile soundness and natures of defective piles.

Jan 1, 1991

By D. X. Xu

A pump station was constructed at the food of a steep mountain, very close to a riverside. To protect the pump station from being washed out, and to guarantee the stability of the steep hillside behind the pump station and the safety of the foundation pit when the station was built, cast-in-place R.C. diaphragm walls (Fig. 1) were clesigned in front of and on both sides of the pump station. This wall was 130m long, 0.8m wide and 29m deep. The diaphragm walling on both sides of the pump station served to prevent landslides and to fix anchor piles. The 55m long diaphragm walling in front of the pump station served as a temporary shuttering which kept earth and prevented water from permeating when the pump station was under construction. After the pump station project was finished, static blasting method was used to blow up the wall body which was 10m beneath the ground so that the water from the river could come into the pump station. The remaining wall body below this level was kept to prevent soil from being washed out. [ ]

Jan 1, 2010

By Ivan Hee

The 2.5km long bridge over the Beauharnois Canal and St. Lawrence Seaway is a major structure in the new Autoroute 30 project near Montreal. Foundations for the bridge consist of footings on bedrock, driven piles, and drilled shafts. This paper describes the design, verification, and construction of 1.85m diameter drilled shafts socketed into very strong and abrasive dolomitic sandstone. Two loading tests on sacrificial, heavily-instrumented, 1.18m diameter test shafts using Osterberg load cells were performed, with telltales installed to monitor a possible rock cone failure mechanism. The loading tests resulted in a revision to the initial design and provided a greater understanding of the cone uplift mechanism in rock. Insights gained are discussed and economies of the load testing program presented. Construction methodologies are also presented.

Jan 1, 2011

By Steni Stefani, Sanjay Dave

"This paper describes an innovative method, used for the first time in India, for the construction of a 1.0metre-thick positive plastic concrete cut-off wall (CoW) at the upstream toe of the dam at the Kishanganga Hydro-Electric Project in Jammu & Kashmir- India. The extremely difficult bouldery geology with an overburden laden with very hard Panjal Volcanics (quartz, feldspar, muscovite and chlorite minerals) boulders of up to 0.8m to 1.8 metres in size with UCS of up to 265 MPa and the requirement of socketing the CoW into the underlying hard bedrock (UCS 265 MPa) for 1.50m made the choice for the excavation methodology critically difficult. After having evaluated several other existing methods – including hydromill trenchers – the Civil Contractor Hindustan Construction Company, in agreement with its Foundations Engineering Consultant (Ricerca e Sviluppo – Cantieri e Gestioni) opted for a two-stage construction method: firstly, preliminary full-depth drilling and “surgical” blasting with full-length inclinometer checking of borehole verticality to ensure the exact location of rock fracturing and fragmentation coincided with the required position and that it was vertical, notwithstanding efficient trenching into the bedrock of a nominal 1m by 1.5m section; and, secondly, excavation by using heavy duty mechanical rope grabs made locally and developed by the Consultant in collaboration with the Contractor. The details of the methodology and the salient construction data is presented and commented for the 33-metre deep CoW installed at a working platform elevation of 2364.50 m above sea level in a very remote area.BACKGROUNDThe Kishanganga Hydro Electric Project (KGHEP) is a ROR (run-of-the-river) project is located on the Kishanganga River some 140kms North-West of Srinagar, capital of Jammu & Kashmir State of India, for generating 330MW of power in a 90% dependable annual year. The key components of the project are: Concrete Face Rockfill Dam (CFRD), Chute Spillway, Plastic Concrete Cut-off Wall (CoW), Head Race Tunnel (HRT), Surge Shaft (SS), Inclined Pressure Shaft (PS), underground Power House and Transformer Hall, Tail Race Tunnel (TRT).The Power House Site is accessible throughout the year from Srinagar while the remote Dam Site, with its tortuous road climbing the Rajdan Pass at 3556m (11,667 ft) above sea level and several 20-tonne capacity Bailey bridges removed prior to snowfall, remains inaccessible for around 4 months between mid-November to mid-May due to winter and heavy snowfall - the only access is by helicopter, weather permitting. Temperature at the Dam Site drops down to minus 27degrees Celsius during winter, therefore, careful planning from the beginning was most essential for the successful delivery of the Project.This paper deals with the Cut-Off Wall construction which was performed, for the first time in India, adopting a “Drilling and Surgical Blasting” method. However, this technology is not new and diaphragm wall excavation with the aid of drilling and blasting has already been done in some of the projects globally; namely:"

Jan 1, 2017

By Darrell L. Beddard

Pile driving started October 29, 1993 and was completed on January 27, 1994. Field work included driving piling from ground surface at one site and at or near proposed footing elevations for the remainder. Piles were driven to specified tip elevations or the elevations directed by the Project Manager. In an attempt to address what installation technique(s) performed the best, several methods were used, including varied predrilled depths, open ended piles, closed ended piles, and the use of both impact and vibratory hammers. Piles were driven closed ended where possible to study the feasibility of this option to reduce construction costs associated with pile cleanout. Piles were driven to different depths to measure capacity variations. The 24-inch (610 mm) diameter piling were driven in one piece while the 42-inch (1.07 m) diameter piling was driven in two segments. A total of 79 piles were driven for the four sites, 74 of the 24-inch (610 mm) diameter and 5 of the 42-inch (1.07 m) diameter. Various hammers were used to determine which hammers provided viable solutions to the potential problems anticipated in the design phase. Hammer selection was based on the driveability studies. Equipment included a 175 ton (1.56 MN) crane, support crane for pile stabilization, crane mounted auger drill, offshore leads, Delmag D30-32, D46-32, and D62-22 diesel hammers, an HPSI 2005 single acting hydraulic hammer, a Foster IHC S-90 double acting hydraulic hammer and a Kencho VM2-25000AII vibratory hammer with the weights set to produce 17,500 pound-inch (1.98 kN-m) of eccentric moment.

Jan 1, 1996

By Federico Pagliacci

"Many existing dams are subject to underwater seepage due to subsoil conditions, like deep alluvial deposits or pervious rocks or karst. Remedial works are necessary in order to install new cut-off walls to stop the water flow. In some cases the cut-off walls have to be executed at depths never reached so far, and difficult to reach with traditional foundation techniques. In many cases the Hydromill technology proved to be the best system to overpass rocky layers and ensure the required verticality. The maximum depth reached by the industry was in the range of 120-150 meters. This article describes the test performed to excavate and cast in place a 3.2x1.5 m panel to a depth of 250 m. The article will also describe the stratigraphy of the site down to 250 meters, as well as the technique adopted to achieve the said depth with deviations from verticality of 30 cm along the longitudinal axis (0.12%) and 20 cm along the transverse axis (0.10%), measured at the bottom of the excavation. The concreting of the panel, for about 1,100 m³, with plastic concrete in the lower portion and conventional concrete in the upper portion will be illustrated. Finally, the tests performed during the excavation and after concrete casting will be also described, with special attention to the continuous directional core drilling that was performed along the whole length of the panel to verify the results of the deviation from verticality, through the onboard instruments, and to control the quality of concrete at a depth never reached before. IntroductionMany existing dams are subject to underwater seepage due to subsoil conditions, like deep alluvial deposits or caves and cavities or acid solutions in the bedrock formations.Conventional remedial works generally consist in the construction of an additional cut-off wall throughout the dam body and the subsoil, in most cases being deeper than the original one. Today, many examples of successful remedial cut-off walls allow the engineers to design the most suitable solution according to the dam and subsoil characteristics and nature.The real difficulty stems from the depth at which the new cut-off wall has to be socketed in competent rock or soil, so as to eliminate underwater seepage. The maximum depth ever achieved with a cut-off wall is 122.5 m for the remedial work of Mud Mountain Dam, Washington, USA, in 1988-1990. This 0.85-1.0 m thick cut-off wall was realized by means of a Hydromill, by excavating single 2.8 m-wide secant panels."

Jan 1, 2017

By Raffaella Granta

Mosul Dam is an earth fill dam located on the Tigris River, approximately 40 km (25 mi) northwest of Mosul, Iraq. The construction of the dam was completed in 1984. It is one of the largest multipurpose dams in the Middle East, and the largest dam in Iraq. The dam provides flood control, irrigation, power generation and water supply. At 113 m (371 ft) high and 3.65 km (2.3 mi) long, the reservoir has a storage capacity of 11.1 billion m3 (392 billion ft3) of water. The main hydroelectric power station has four turbines for an installed capacity of 750 MW. The discharge system includes two bottom-outlet tunnels of 10 m (33 ft) diameter, a five-gate service spillway and an emergency fuse plug spillway.

Oct 1, 2022

By Tai Luu, Michael McNicholas, James C. McIntyre

The Jersey City Municipal Utilities Authority (JCMUA), discovered that an existing sewer pipe had collapsed under the New Jersey Transit Conrail Railroad between Pine Street and Ash Street in Jersey City New Jersey. Immediate action was taken to abandon the pipe in place and install a new sanitary sewer. The borings showed 10-20 ft (3.04 m.- 6.09 m) of competent fill overlaying approximately 8 ft. (2.44 m.) of compressible peat and organics. Groundwater was at 8 ft (2.44 m) below ground level. The poor condition of the soils at subgrade could not withstand the extreme weight of the jacking machine or the thrust force required to push the casing from the launching pit to receiving pit. The support of excavation (SOE) would therefore not only need to retain the soil to allow the jacking equipment to reach subgrade at 14 ft (4.27m) below working grade, but also the back wall of the SOE would need to be sufficiently robust to function as the reaction block for jacking operations. The alignment and allowable tolerance for the jacked casing was minimal, therefore the performance of the SOE was extremely critical to the success of jacking operations. This paper will discuss in detail the design concepts that were developed and implemented by the team to overcome these obstacles. HISTORY The discovery of a collapsed section of an existing sanitary sewer led the Jersey City Municipal Utilities Authority to act on an emergency contract. The project design team was tasked with developing an abandonment plan for the broken pipe and installation of the new pipe through challenging geology. The new 180 ft.(54.96 m) long, 54-in. (1.37 m) . diameter sewer pipe was designed to be contained within a 72-in. (1.83 m) protective steel casing. The installation of the new sewer pipe would require a detailed understanding of the geology. The geotechnical subcontractor assembled a subsurface investigation report on November 2nd, 2017. It was quickly realized that the only way to replace the pipe was with a jacked pipe system since the large grade change and the Conrail Right of Way created no other alternative. Delaying or closing the railway was absolutely not an option as that particular railway served as the main heavy-haul route to and from Jersey City. It became apparent that a major obstacle to pipe jacking was the challenging geology present across and beneath the proposed sanitary sewer. The following challenges faced the design team prior to the installation of the replacement pipe:

Jan 1, 2019

By Serhat Baycan, Mikias Yohannes

"Kuala Lumpur Karst is a complex limestone formation that is characterized by presence of cavities, solution channels, pinnacles and floaters. Basement excavations in such geological formations are usually challenging, mainly owing to the unpredictable rock head depths and potential for groundwater inflow. Any excavation support system should have adequate robustness and water tightness. Traditionally, Secant Bored Pile walls (SBP) with struts are the preferred option for karst ground. This paper discusses a cost effective and innovative alternative solution for a particular site – using Deep Soil Mixing (DSM) and using Contiguous Bored Piles (CBP) together with Ground Anchors (GA). The site, located around one of the busiest areas of Kuala Lumpur, is a 5,700 m2 commercial and residential development. A 16.0 m deep excavation was needed for four levels of basement and excavation support along the 275 m perimeter of the development. Within the site, the depth to rock head varied from 6 m to 19 m. The basis for each solution and conditions for its suitability are discussed in detail. Some design considerations and construction challenges are also presented. The performance of the two retention systems during excavation are presented, together with comparisons versus design predictions. Suggestions for future development are also given. Advantages of this approach compared to other traditional approaches are highlighted.1. INTRODUCTIONThe geology of Kuala Lumpur is among the most complicated and geotechnically challenging formations in South East Asia. The majority of the city falls into the Kuala Lumpur Limestone formation; which is a thick, highly-weathered and cavernous limestone. This formation is pure calcitic to dolomitic in composition, having infrequent schist and phyllite interbedding (Gobbett et al., 1973).The KL limestone has a highly karstic topography dotted with cavities, ravines, interconnected subterranean channels, pinnacles, overhangs, floaters and slump zones (Tan, 2006). This results in erratic bedrock profiles even within short distances. It is not uncommon to see a precipitous rock head incidence within short distances in the same site. In most parts of the City, the bedrock is typically encountered ranging from very shallow depths to about 30.0 m. The exception to this is at the heart of the City, where Kenny Hill formation prevails above the KL limestone. In such cases the limestone bedrock can be encountered much deeper. The erratic rock head profile and the highly karstic nature of the KL limestone makes it a geotechnical challenge requiring careful consideration of suitable engineering solutions.1.1 – Site DescriptionThe site, located in downtown Kuala Lumpur, is abutted by a busy street on the North. Before development, the site previously served as a car park. To the west an access road separates the site from an empty lot; while on the east, the lot is bounded by light weight residential and commercial buildings. On the south side, the site is bordered by a road that separates it from a prominent Shopping Mall in the City. A layout plan and an artist’s impression of the finished development is shown in Figure 1."

Jan 1, 1900

By Claudio Asioli

"The project’s goal was to construct the Al Ghazala Intercontinental, a multi-use development in the bay area of Tripoli overlooking the Mediterranean Sea. The site of the project is located approximately 500 ft (150 m) from the Mediterranean coast, near the Al Ghazala roundabout in the town center of Tripoli, Libya. The investor of the project was Magna Properties Group, Ltd. – Libya, the main contractor was Man Enterprise S.A.L., and the design and construction management was performed by Dar Al-Handasah Engineering. Trevi S.p.A. was contracted to perform the design and construction of the anchored diaphragm walls and dewatering systems for the excavation of a two-level basement car park, which extends across the full footprint of the site.The site was approximately 640 ft by 230 ft (195 m by 70 m) in plan and nearly flat. The groundwater level typically varies from about 11 ft to 23 ft (3.4 m to 7.0 m) above mean sea level. To construct the required raft foundation, it was necessary to excavate the area down to El. -15.7 ft to -26.3 ft (-4.8 m to -8.0 m), which resulted in an excavation depth ranging from about 27 ft to 39 ft (8.3 m to 12.0 m) below the existing ground surface.Subsurface ConditionsThe subsurface site investigation was performed in three phases by Al-Tamier Engineering Consulting Bureau. During Phase 1, a preliminary investigation was undertaken during the early stages of the project to obtain information about the general stratigraphy and groundwater level at the site. Phase 2 was performed to obtain subsurface information and design parameters, and Phase 3 was performed as a supplementary ground investigation to investigate unexpected ground conditions identified during Phase 2. In total, 14 boreholes were drilled to depths ranging from about 80 ft to 180 ft (24 to 55 m). The generalized subsurface profile is quite heterogeneous, and is predominantly composed of sand with silt and gravel that is underlain by limestone, calcarenite and claystone"

Jan 1, 2017

By Claudio Asioli

"The project’s goal was to construct the Al Ghazala Intercontinental, a multi-use development in the bay area of Tripoli overlooking the Mediterranean Sea. The site of the project is located approximately 500 ft (150 m) from the Mediterranean coast, near the Al Ghazala roundabout in the town center of Tripoli, Libya. The investor of the project was Magna Properties Group, Ltd. – Libya, the main contractor was Man Enterprise S.A.L., and the design and construction management was performed by Dar Al-Handasah Engineering. Trevi S.p.A. was contracted to perform the design and construction of the anchored diaphragm walls and dewatering systems for the excavation of a two-level basement car park, which extends across the full footprint of the site.The site was approximately 640 ft by 230 ft (195 m by 70 m) in plan and nearly flat. The groundwater level typically varies from about 11 ft to 23 ft (3.4 m to 7.0 m) above mean sea level. To construct the required raft foundation, it was necessary to excavate the area down to El. -15.7 ft to -26.3 ft (-4.8 m to -8.0 m), which resulted in an excavation depth ranging from about 27 ft to 39 ft (8.3 m to 12.0 m) below the existing ground surface. Subsurface ConditionsThe subsurface site investigation was performed in three phases by Al-Tamier Engineering Consulting Bureau. During Phase 1, a preliminary investigation was undertaken during the early stages of the project to obtain information about the general stratigraphy and groundwater level at the site. Phase 2 was performed to obtain subsurface information and design parameters, and Phase 3 was performed as a supplementary ground investigation to investigate unexpected ground conditions identified during Phase 2. In total, 14 boreholes were drilled to depths ranging from about 80 ft to 180 ft (24 to 55 m). The generalized subsurface profile is quite heterogeneous, and is predominantly composed of sand with silt and gravel that is underlain by limestone, calcarenite and claystone."

Jan 1, 2017

By Bengt H. Fellenius

An upgrading and straightening of a highway included building a bridge across a small river. A routine site investigation was initiated to determine the conditions for designing the foundation of the bridge. The proposed bridge was a two-lane highway bridge in one span with a total length of 30 m (100 ft), as indicated in Fig. 1. It was to be placed about 20 m (66 ft) upstreams of the bridge for the existing highway. The site investigation included one boring at each abutment with soil sampling and in-situ vane testing and placed about halfway up the slope from the small river at ground surface elevation + 54 m. Within the investigated maximum depth of 40 m (130 ft), the soils at both borehole locations consisted of a thin clay crust over a thick deposit of soft sensitive clay with a natural water content of about 70 % and a liquid limit of about 60. The undrained shear strength below the crust was about 20 KPa (400 psf) and increased slightly with depth. The sensitivity was high, about 40.

Jan 1, 1987

By Theo. A. M. Salet

The historic centre of one of the most beautiful cities in Northern Europe -Amsterdam - is being excavated to accommodate the new North/South metro line. This new line is due for completion in 2012, and will link the Buikslotermeerplein district north of the harbour, underneath the Central Station and the old city with its gables and picturesque canals, to the commercial centre in Amsterdam Zuid/WTC. Three underground stations are being construction in the old city at Rokin, Vijzelgracht and Ceintuurbaan. The logistics of working in the middle of an historic city are demanding -maintaining tram, vehicular traffic and pedestrian access along narrow streets, providing suitable protection for the public alongside the working areas, arranging adequate delivery routes, as well as monitoring the old and mostly historical buildings for potential settlement. Safety of both the public and adjacent properties is paramount. Diaphragm walling - 1.2m & 1.5m thick and up to 48m deep - was chosen as the support system for the three deep metro stations. Challenging engineering as well as state-of-the-art equipment to construct the diaphragm walls was needed in order to meet the tight working specifications, in the narrowest locations imaginable. Extreme conditions call for innovative solutions.

Jan 1, 2006