Search Documents

By Chu E. Ho

This paper describes a case history involving the use of the Equivalent Driving Energy concept for evaluating timber piles that failed to achieve the termination criterion traditionally based on final driving resistance and minimum pile depth. It was assumed that a pile would be acceptable if the overall energy delivered during pile driving was at least equal to that of an ideal pile that achieved the design pile capacity established during an initial load test. The equivalent driving energy was determined by integrating the cumulative driving resistance profile over the embedded length of the pile within the founding soil strata. The required equivalent driving energy was calibrated using representative restrike PDA capacities of production piles as piling progressed. This approach enabled piles that failed to meet the original acceptance criterion to be re-evaluated, resulting in a significant reduction in the number of rejected piles that would otherwise have to be replaced.

Abouleid,A.F.327 Ajdic, I.451 Albert, L.F. 221,307 Alem, A. 525 Asama, T. 431 Avgherinos, P. J. 373 Baker Jr, C.N. 331 Balossi Restelli, A. 171 Beckwith,G.H.33 Bellini, A. 469 Bermingham, P. 481 Bertero,M. 171,535 Beyer, M. 503 Bottiau, M.41 Botto, G. 205 Bruskeland, O. 337 Budhu, M. 349 Bullivant, R.A. 181 Bustamante, M.G. 185, 475, 535

Jan 1, 1994

By Shoichi Tsukuni, Akihiko Uchida, Kazuo Konishi

"In order to investigate the effect of grid-form deep mixing walls as a countermeasure for liquefaction damage to roads and private houses in Urayasu, Japan, three dynamic centrifuge model tests were conducted. Urayasu is located in the Tokyo Bay area, and private houses in the city incurred severe damage due to liquefaction during the 2011 Tohoku earthquake. In grid-form deep mixing walls design, the distance between grid-form walls is critical to prevent liquefaction. This study clarifies the relationship between the settlement of private houses and the distance between grid-form walls under the conditions that exist in Urayasu.INTRODUCTIONMany private houses in Urayasu, Japan suffered severe damages due to liquefaction during the 2011 Tohoku earthquake (Photograph 1). Fig. 1 shows the location of Urayasu and the maximum acceleration of the observed seismic waves in the Tokyo Bay area. At Urayasu, the duration of the seismic waves (hereafter called the Urayasu Wave) was about 2 min. The maximum acceleration was 1.57 m/s2 (Fig. 2), which is relatively small. The damages occurred in the land reclamation areas that consist of loose sand with an SPT-N value less than 10.To prevent liquefaction in future, it is necessary to adopt suitable countermeasures in the areas where many private houses suffered severe damages. Grid-form deep mixing walls are one such countermeasure. Fig. 3 and Photograph 2 show grid-form deep mixing walls. Walls are constructed using the deep cement mixing method. Fig. 4 shows a plane view of planned grid-form deep mixing walls for roads and existing private houses in Urayasu."

Jan 1, 2015

By Jeongbok Seo

This paper describes successful application of driven tapered-steel-pipe piles for two large-scale projects in the New York metropolitan area: Rego Park Mall, Rego Park, N.Y. and 164 Kent Avenue, Brooklyn, N.Y. The combination of side friction and end bearing resistance produced by tapered-steel-pipe piles has been well-recognized as greater than the side friction and end bearing resistance by pipe piles. Forty-four tapered piles were driven and tested at these two sites. Design pile load for the two sites was 260 kips for Rego Park Mall and 400 kips and 300 kips for 164 Kent Avenue. To measure the pile-drive hammer efficiency, the compressive stress in the pile, and to estimate the ultimate bearing capacity of the pile, dynamic load testing using a Pile Driving Analyzer (PDA) was conducted on index piles at the sites. Subsequent to the field testing, data analysis using the Case Pile Wave Analysis Program (CAPWAP) was conducted. Restrike PDA analysis and full-scale static load tests were performed on the selected test piles. Test piles at the project sites exhibited significant time-dependent increases in bearing capacity caused by the effects of "set-up" or "soil freeze." The dissipation of excess pore-water pressure in the soil, which had been disturbed and remolded by driven pile, was generally considered the primary cause of set-up. The increase at the subject sites ranged from 100 to 300 percent of the capacity measured at the initial driving. This paper discusses the results of various types of load testing on tapered piles and the set-up effects by comparing PDA test results acquired during and after pile driving. Finally, an empirical relationship for the New York metropolitan area has been offered for quantifying set-up.

Jan 1, 2008

By Ambarish Ghosh, Subhaprasad Chakraborty

"Construction of basement floors has become necessary to meet the requirement of parking in office and residential complexes and in hospitals for radiotherapy treatment. Important projects coming up in Kolkata are mostly in closer proximity of residential buildings, office buildings and historical monuments. Sheet piling is mostly used as temporary shoring system during construction. Deep excavation in urban environment creates great problem related to construction induced vibration due to driving of sheet piles for basement, pile driving etc. which raises the chances of damage of adjacent buildings and nearby structures. Vibratory sheet-pile driving is the most common method of sheet pile installation. The knowledge of induced vibration due to this phenomenon is still very deficient. This paper presents the analysis of measured vibration data collected from different sites of Kolkata with varying soil profile. Typical two case studies of sheet pile and pile driving has been presented and the vibration values are analysed. The responses of the vibration are reported in terms of peak particle velocities (PPV). To evaluate the effects of vibration due to pile driving two aspects have been considered: the effect of the energy entering the ground from the pile and the effect of the soil condition.INTRODUCTIONIn urban areas infrastructure development projects are mainly located adjacent to existing structures like residential buildings, offices and historical structures. The construction work of such project influences the surrounding environment as well as human perception (Wiss 1981). During the construction of basement for residential complexes and hospitals sheet piling is mostly used as temporary shoring system or as to support the earth mass. The vibration induced due to driving of piles and sheet piles have been presented herein. Deep excavation projects close to existing structures increase the concern of environmental impact. For this reason the vibration assessment and prediction has become a subject of great interest. It is important to develop a site specific model for predicting the ground vibration resulting from pile and sheet pile driving at the construction sites. The developed model gives the efficacy to guide the engineer to select the construction methodology ensuring the safety of the surrounding structure. The model developed here is site specific and the parameters that has been used are dependent on the soil condition and the energy source."

Jan 1, 2015

By José Carlos A. Cintra

This paper addresses a new experimental procedure to measure the shaft friction and the base resistance of bored piles during static load tests. It is proposed that a set of polystyrene foam discs, placed between the shaft and the base of the pile, be used instead of the usual instrumentation. Throughout the initial stages of the loading test, the foam discs will allow only the mobilization of the shaft friction. The load x settlement curve clearly shows that the shaft friction vanishes at low settlement values. As the load test proceeds, the base resistance is also mobilized. This procedure was used in two belled piles bored at the Experimental Foundation Field of the University of São Paulo, at São Carlos, Brazil. Both piles were 8 m long and had a shaft diameter of 0.6 m. The enlarged base had a diameter of 1.5 m and a height of 0.9 m. Twenty foam discs with a thickness of 20 mm each were placed between the enlarged base and the shaft of the pile. The load tests indicated ultimate shaft frictions of 28 and 30 kPa for measured settlements of 8.98 and 7.39 mm. Base resistance values at failure were 617 and 499 kPa, for a chosen settlement of 10% of the pile base diameter. The proposed approach seems to be straightforward, efficient and inexpensive.

Jan 1, 2002

By Jochen Maurer, Dr. Christian Hoyme, Dr. Hans Regler

Currently, it is very difficult to obtain qualitative and quantitative information about the status and production process of a construction site. As a rule, companies depend on reports from on-site experts. There is no end-to-end digitalization due to the mobility of equipment and ever-changing locations. Equipment from different manufacturers, especially in special foundation engineering, is highly specialized. Any data collected by this equipment is recorded in proprietary formats and made available on the manufacturers' platforms. This exacerbates the situation, making simple analysis of performance indicators impossible. Most functions such as construction diaries, equipment utilization analyses, etc. are implemented only as standalone solutions. This does not allow for prompt visualization and intervention in critical process sequences because the construction site process is usually managed using a cost-based method. Furthermore, special foundation engineering requires a high level of expertise in an extremely wide range of construction processes. In this article, the results from a set of non-proprietary performance analysis tools are presented using numerous practical examples. Once a construction element is completed, the equipment data is immediately transferred to the platform using the latest cloud technology. Because the data is normalized, construction progress can be documented immediately, even for mixed equipment fleets. Bottlenecks can be immediately detected by visualizing the current performance of the production process, which is broken down into individual steps. Modern analyses of this equipment data improve quality, thereby providing better information about current performance. These sets of tools are essential for changing from the current monetary or cost-based method of process management to time- and bottleneck-oriented management. This makes it much easier to identify the critical path during projects. The article shows that processes can be documented and managed.

By Takeshi Maki, Kh. Adeel Tariq

"The lateral resistance of the structure plays an important role during seismic event and it can be increased by using ground improvement. In this study an attempt has been made to investigate the effect of cement-treated sand on the lateral capacity of the pile. The behavior of piles surrounded by sand only and cement-treated sand confined in a steel box (30 x 30 x 50 cm) which is subjected to lateral cyclic load has been investigated. Piles having a diameter of 2.5 cm and embedded to a depth of 45 cm were used. Steel and aluminum piles were used to investigate the effect of flexural stiffness on the lateral capacity of the pile. Bottom supports of piles were also changed from pinned to fix. Well graded sand compacted to 70% of relative density (RD) was used. Cement-treated sand having a compressive strength of 3.7 MPa was used. Displacement controled lateral load tests were performed and cyclic loads were applied until pile displacement was 4%, 10%, 20%, 35%, 50%, 75% and 100% of pile diameter. Results evaluated are compared with common method of analysis like Brinch hansen (1961), Brom (1964), Poluos (1980) etc. Results have indicated that the stiffness of a pile affects its lateral capacity. The introduction of central cement-treated sand part increased 5 times the lateral capacity of piles as compared with a sand only condition.IntroductionPiles are used extensively around the world to support loads of structures. Piles are commonly used to carry axial load, but in some structures, the lateral capacity of the pile is more important than the axial capacity: for example piles supporting earth retaining structures, electric tower foundation, etc. Structures can be subjected to both axial and lateral forces, like structures constructed at harbor that are subjected to lateral force due to waves action; and structures built in earthquake prone areas like Japan."

Jan 1, 2017

By Manasi Wijerathna, D. S. Liyanapathirana

"Deep cement mixing is a popular soft ground improving technology that improves the bearing capacity and settlement characteristics of natural soil. When Deep Cement Mixed (DCM) columns are installed attached to each other in a wall configuration, the walls are capable of resisting bending moments and shear forces in the direction transverse to the columns. Therefore, installing DCM walls beneath the embankment slope perpendicular to the alignment of the embankment is a proper solution to prevent excessive lateral deformations of the embankment. Previous research studies have shown that failure patterns of DCM column walls are different to failure patterns of individual DCM column rows, under lateral loads. This study investigates the failure patterns of embankments where DCM column walls are located beneath the slopes, with respect to DCM wall strength, DCM column wall width and the spacing between DCM walls. 2D and 3D numerical models developed using the ABAQUS/standard finite element programme, were used in this investigation. Results show that the DCM wall strength and width of the DCM wall have a significant influence on the failure mode and the critical failure surface of the embankment. 3D simulation results demonstrate that the failure due to soil extrusion between columns was less pronounced in embankments improved with DCM walls, due to the interaction between the DCM walls and the surrounding natural soil.INTRODUCTIONEmbankments constructed over soft ground are highly susceptible to global slope failure and excessive displacements due to combined effects of vertical and lateral loads beneath the embankment slope (Zheng et al., 2009, Han and Gabr, 2002). The overall stability of the embankment can be significantly improved by improving the soil beneath the slope of the embankment using Deep Cement Mixed (DCM) column rows or overlapped DCM column walls (Jamsawang et al., 2015, Larsson and Broms, 2000, Topolniki, 2004, Broms, 1999). According to the literature, the improved ground experience different failure modes other than shear failure, such as separation of columns, overturning, shear failure along the columns or dowel action (Broms, 1999). Some of the failure modes reported by Broms (1999) are shown in Fig. 1. The ultimate failure mode depends on the geometry and the strength of the improved ground (Jamsawang et al., 2015, Kitazume and Maruyama, 2006, Kitazume and Maruyama, 2007)."

Jan 1, 1900

By Massimo Poggio, Gabriele Balconi, Andrea M. R. Pettinaroli, Mario Ruggiero, Riccardo Castellanza

Grouting technologies are ground treatment techniques used for modifying the behaviour of a mass of soil or rock by injecting a mixture. The sleeved port pipes (also called Tube A Manchette) are highly diffused for grouting treatment of coarse soils and fissured rocks. This paper describes a combination of jet grouting and rock grouting with MPSP (multiple packer sleeve pipe) technique that has been used to realize waterproof curtains under fluvial structures for a cascade hydro-power plant. This is composed by five mini hydro-power plants, placed along the Iskar River, in Bulgaria, and composed by a penstock followed by the power house, a spillway, and an earth dam containing the reservoir. The geology of the site is characterized by an upper alluvial deposit lying over the bedrock. In each site, similar treatments were carried out: an impervious curtain along the plant section, obtained by executing jet-grouting columns in the surficial alluvial layers and grouting the underlying fractured rock by means of port pipes. The temporary embankment, built during the works for protecting each site from the possible river floods, has been waterproofed and stabilized by reinforced jet-grouting columns. The grouting processes have been controlled and monitored by a computerized system. INTRODUCTION The Iskar river cascade hydropower plant is situated northern of Sofia, Bulgaria, and it is composed by nine plants. Actually five of them have been built and produce energy. Each plant is composed by a penstock followed by the turbine building, a spillway, and an earth dam that contains the reservoir. The Iskar rivers runs in a narrow valley characterized by diorite or diabase rocks, with an upper deposit of alluvial soil, composed mainly by gravel and sand. Each plant requires an impervious curtain under the structures and in correspondence of the earth dam: this has been obtained by means of a jet grouting treatment of the alluvial coarse soil, and a grouting treatment with cement mixtures of the underlying rock using the MPSP technology. During the construction of the structures, the site has been shielded from the river water by a temporary earth embankment that has been statically improved and waterproofed by jet grouting columns reinforced with steel tubes; this allowed to work without interruption even in case of flood of the Iskar river.

Jan 1, 2019

By Lisheng Shao

Soil mixing and jet grouting have been widely used to support heavy structures such as tanks, cement silos, and storage buildings. Although the installation methods vary between soil mixing and jet grouting, the end product of soil-cement columns behaves similarly in supporting structure loads. In many cases, soil-cement mass treatment offers the owner savings over driven/drilled piles. This paper discusses the design methodology, production work, and quality control, with supporting figures, of a recent large complex tank farm project. The project consisted of constructing six above-ground steel storage tanks and an approximately 700-foot-long fill slope. The tank farm site is located in an industrial area of southern California, with highly variable subsurface conditions consisting of compressible soils and buried construction debris. The compressible soils necessitated that the new tanks be supported on deep foundations. A test pile program performed previously at the site showed that conventional driven concrete piles were not feasible because of buried construction debris, therefore a soilcrete system was proposed. Site design included evaluating the total and differential settlement and column group bearing capacity under both static and seismic loads. Extensive field and laboratory testing confirmed the design soil-cement strength and modulus of both the soil mixed and jet grouted soil-cement columns. The project operation and quality control programs are also included in this paper.

Jan 1, 2010

By Martina Balic

Dynamic properties of the drilled shaft foundations supporting Doremus Avenue Bridge were determined by forced vibration testing. The main objectives of the substructure testing at Doremus Avenue Bridge were: (1) site evaluation with respect to the dynamic soil properties, and, (2) shaft evaluation for the purpose of definition of their dynamic stiffness. The site characterization entailed crosshole testing for the purpose of evaluation of the shear modulus profile. The drilled shaft impedance evaluation was done through forced excitation using an electromagnetic shaker. The responses of the tested shaft, as well as the response of adjacent shafts, were measured for the purpose of evaluation of the shaft interaction. To gain a better insight into the shaft dynamics, one of the shafts was instrumented with five triaxial geophones distributed along the full length of the shaft. The scope and results of the site characterization, shaft impedance and shaft interaction evaluation are presented.

Jan 1, 2004

By P. Davies

The Hillside Smelter presently under construction at Richards Bay, Republic of South Africa, will be, on completion, the fifth largest aluminium smelter in the world. The site selected for this plant is underlain by sandy soils of variable density to depths of 30m or greater. In order to firmly establish pile founding depths required for alternative pile types in the variable subsurface conditions prevailing across the site, a pre-construction test piling programme was conducted incorporating piles instrumented with resistance strain gauges. The results allowed analysis of the relative contributions of end-bearing and shaft friction to the overall bearing capacity of each pile type and permitted comparison with the predictions of conventional static bearing capacity analyses. Conformance with acceptance criteria in respect of allowable pile head movements for single piles was also examined.

Jan 1, 1996

By Shigenori Horikawa, Nobutaka Tanaka, Toshiro Hara, Kengo Yamamoto

"The CDM-LODIC method(Low Displacement and Control method), a modified the CDM(Cement Deep Mixing) method, reduces the ground displacement through the removal of in-situ soil equivalent to the amount of slurry injection using the continuous auger flight attached on the shaft above the conventional the CDM mixing tool. The reduction of ground displacement minimizes the impact on adjacent buildings and other infrastructures. Since the development of the CDM-LODIC in 1985, this method has been used for more than 900 projects with total volume of improved soils exceeding 5.3 million yd3 (7 million m3). The ground displacement that could be caused by deep soil mixing is controlled by balancing the volume of discharged soil and the volume of slurry injected for soil mixing. This paper presents the ground improvement work for the Sanriku Coast Expressway Project using the CDM-LODIC method to 1) control the ground displacement during ground improvement to minimize the impact to existing buildings and facilities and 2) utilize low height CDM-LODIC equipment to avoid potential damage to critical facilities in the vicinity of ground improvement area and avoid interference on the normal operation of the Ishinomaki Red Cross Hospital.INTRODUCTIONSanriku Coast Expressway is a reconstructed highway, which is part of an early restoration program to recover from the Eastern Japan Earthquake of March 11, 2011. This highway extends 223 mile (359 km) and connects the Pacific Coast regions of three prefecture of North Eastern Japan as shown in Figure 1. Along a section between Yamoto - Ishinomaki road, the highway was expanded from two lanes to four lanes to mitigate traffic congestion for the adjacent city center and hospital and to serve as an efficient transportation route for emergency or disaster relief needs as shown in Figure 2. Deep mixing ground improvement with an area replacement ratio of 50% was designed to provide settlement control under the new fill embankment of the expanded highway as shown in Figure 3. The original CDM treatment layout using 5.2ft (1.6 m) diameter columns is shown in Figure 4."

Jan 1, 2015

By Racquel Nottingham, Marc Mastrantuono

Micropiles often provide a favourable solution for many deep foundation problems especially when significant site constraints such as confined construction sites or vibration limitations have been identified. Often the durability of buried steel elements are heavily scrutinized in order to effectively determine the rates of corrosion and methods to reduce this while still maintaining the structural integrity of the engineered solution. Practices such as sacrificial corrosion loss and the introduction of plastic sheaths have become the go-to methods of corrosion protection. Since the introduction of the micropile, other solutions have been developed, namely protection with an adequate grout encapsulation. This paper will explore corrosion protection of micropiles and the guidelines provided in the published codes and norms. Since few codes define the exact way to verify the durability of these micropiled structures, the existing data is presented and the analysis of grout encapsulation as an effective corrosion protection method is evaluated.

Oct 1, 2022

By Abid Adekunte

"In recent years, developers have had to deal with complexities associated with numerous cases of deep basement construction in built-up areas. Design and construction of deep excavation support systems in urbanised zones come with many technical challenges. Restricted working spaces often render the use of temporary struts as wall restraint systems unpopular, as working space needs to be maximised. Also, tie-back anchors are often inapplicable due to the existence of adjacent structures. Therefore, developing alternative restraint systems for deep basement structures in builtup areas is becoming increasingly important to the present day basement engineer.This paper is centred on the design, construction and monitoring of enabling works for deep basement structures on three sites in the United Kingdom and Republic of Ireland. Traditional tieback anchorage and propping systems were inapplicable on the sites. As alternatives, separate novel wall restraint systems were developed and adopted, to enable excavation on each of the three sites.Performances of the novel wall restraint systems, as well as the responses of adjacent structures were monitored. Numerical modelling and field monitoring results show the three alternative wall restraint systems to be safe and effective. The paper also highlights the advantages of the novel solutions over conventional methods.INTRODUCTIONRecently, deep basement structures have become popular components of urban building developments. As pointed out by Pearlman et al., 2004, this could be attributed to the inadequacy of surface parking spaces in urbanised zones, while underground parking facilities are also believed to improve both aesthetic and commercial qualities of urban structures.However, while the incorporation of basement structure into new urban development appeals to developers and architects, the engineering design and construction aspects of basement works typically come against a whole lot of complexities and challenges. As highlighted by Wong, 2002, engineering problems associated with basement construction in built-up areas are numerous, some of these include; complicated sub-soil conditions, dealing with excessive active pressures, complex temporary works, proximity of sensitive adjacent structures, high level hazards to construction workmen and surrounding community, inadequate working space, etc."

Jan 1, 2015

By Deep Foundation

Whenever an organization launches an initiative, the question arises whether that initiative has staying power. Or is the initiative, as is quite often the case, merely a fad; that is, just an activity that suddenly becomes popular, but which does not stay popular for very long. When the Federal Highway Adminis- tration (FWHA) started its Advanced Geotechnical Methods in Exploration (A-GAME) initiative, that question was addressed, especially considering the fact that up to 50% of major infrastruc- ture projects suffer impacts to schedule or cost due to geotechnical issues. Many of these issues relate to risks identified directly or indirectly to the scope and quality of site character- ization work. Effective site charac- terization is critical for recognizing. potential problems that may affect design and construction and for ensuring safe, well-performing and cost-effective projects. Grounded on that, knowledge of all available site investigation methods should continue to be shared widely and the application of those methods should be encouraged on an ongoing basis throughout the project lifecycle. The A-GAME initiative covers five technologies: Cone penetration testing (CPT), monitoring while drilling (MWD), electrical geophysical methods, seismic geophysical methods, and optical and acoustic televiewers. Of these, three soil and rock investigation methods were highlighted that are underutilized not only here in the U.S., but also in many places around the world: CPT: a well proven and established method for soil characterization that turned 90 last year, in which continuous in-situ data are col- lected quickly and consistently. Geophysics: the science that assesses the physical properties of the soils and rock using seismic and electrical techniques, which con- tinues to advance in leaps and bounds as the application of well- understood technologies become more powerful.

May 1, 2023

By Abid Adekunte

Traditionally, designers and contractors provide additional external supports to retaining walls through the use of tie-back anchors or braces. Both approaches are known to have their shortcomings; braces limit working space within excavation areas, while tie-backs are seldom used in built-up areas where intrusion into adjacent property of non-cooperative owners has to be avoided or in situations where sensitive structures exist behind the wall. This paper focuses on the design, construction and monitoring of deep excavation support systems on two separate projects located in different ground conditions in the Republic of Ireland. On both projects, conventional ground anchorage and propping were inapplicable. This led to the development and application of two different novel solutions on both projects. Methods of wall performance monitoring on both sites also differ. Wall monitoring results show these innovative methods to be safe and effective. Advantages of the novel solutions over traditional approaches are highlighted.

Jan 1, 2010

"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 Joseph T. Coe, Siavash Mahvelati, Philip Asabere

Characterization of existing foundations remains an important issue as foundation reuse and rehabilitation continue to garner increased attention. In the case of unknown foundations, geophysical and nondestructive testing (NDT) methods have been utilized in the past to evaluate foundation geometry and could serve as useful tools in the case of foundation reuse. A comprehensive study was initiated in the late 1990’s and early 2000’s that evaluated the effectiveness of the available geophysical and NDT technologies to characterize unknown foundations for scour evaluation purposes. At the time of that study, the Multichannel Analysis of Surface Waves (MASW) geophysical method was in its infancy and not widely used. Since then, MASW has become increasingly prevalent in geotechnical applications as the method presents a number of potential advantages when characterizing the subsurface, including rapid testing, increased signal to noise ratio, and ability to resolve velocity inversions. This paper presents a case study that explores the abilities of MASW as an unknown foundation characterization tool. MASW was applied to determine subsurface stiffness at a bridge foundation site in the Philadelphia metropolitan area. One MASW survey line was performed immediately over the foundation of interest and another was performed over a control zone adjacent to the foundation to establish a baseline site profile. The purpose of this testing was to examine whether MASW could establish the geometry of the foundation at this site. This paper presents the site conditions and MASW testing procedures, followed by a discussion of data analysis and interpretation.

Jan 1, 2016