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By Ryan P. Sullivan, G. Alan Klevens, Jian Huang

"BACKGROUNDLake Hamilton in Hot Springs, AR was created in 1932 when the Arkansas Power and Light Co. completed Carpenter Dam on the Ouachita River to generate electricity. Today, the 7,200-acre (2,914 hectares) impoundment is one of Arkansas’s most popular recreational and residential lakes.U.S. 70 crosses Lake Hamilton by means of a seven-span bridge featuring nine steel girders per span. Constructed between 1982 and 1984, the 1,410-foot long (430m) bridge carries four lanes of traffi c across the lake. The bridge is supported by six intermediate reinforced concrete piers composed of hammer heads, stems, footings and seals, which sit on the underlying rock. (See Figure 1). The bridge rises to a maximum of 33 feet (10m) above the surface of the lake and the footings and seals extend a maximum of 29.5 feet (9m) below the surface of the lake. The seals are situated on hard, fractured sandstone and shale.Routine underwater inspections in 1993 revealed large cracks in the lean seal concrete and refl ective cracks in the reinforced concrete footings. Infrastructure Engineers, Inc., The Arkansas State Highway and Transportation Department’s (AHTD) design consultant, then conducted an in-depth underwater inspection of the pier foundations. The investigation included cross-hole sonic logging, singlehole sonic logging, visual examination and strength testing of core samples, and petrographic analysis.The investigation revealed extensive cracking and low-strength concrete within the seals of all intermediate pier foundations. Many voids within the seal concrete had become fi lled with silt. There was evidence of continued seal deterioration between underwater inspections.AHTD and its engineers considered three rehabilitation solutions in the preliminary engineering stage: micropiles, a cofferdam supported concrete jacket, or a pile supported concrete jacket. The three alternatives were estimated to cost $1,250,000; $4,320,000; and $3,030,000 respectively. All three options would transfer the loads from the pier footing directly to the rock below, bypassing the seal concrete."

Jan 1, 2007

By Ryan P. Sullivan, G. Alan Klevens, Jian Huang

"BACKGROUNDLake Hamilton in Hot Springs, AR was created in 1932 when the Arkansas Power and Light Co. completed Carpenter Dam on the Ouachita River to generate electricity. Today, the 7,200-acre (2,914 hectares) impoundment is one of Arkansas’s most popular recreational and residential lakes.U.S. 70 crosses Lake Hamilton by means of a seven-span bridge featuring nine steel girders per span. Constructed between 1982 and 1984, the 1,410-foot long (430m) bridge carries four lanes of traffi c across the lake. The bridge is supported by six intermediate reinforced concrete piers composed of hammer heads, stems, footings and seals, which sit on the underlying rock. (See Figure 1). The bridge rises to a maximum of 33 feet (10m) above the surface of the lake and the footings and seals extend a maximum of 29.5 feet (9m) below the surface of the lake. The seals are situated on hard, fractured sandstone and shale. Routine underwater inspections in 1993 revealed large cracks in the lean seal concrete and reflective cracks in the reinforced concrete footings. Infrastructure Engineers, Inc., The Arkansas State Highway and Transportation Department’s (AHTD) design consultant, then conducted an in-depth underwater inspection of the pier foundations. The investigation included cross-hole sonic logging, singlehole sonic logging, visual examination and strength testing of core samples, and petrographic analysis.The investigation revealed extensive cracking and low-strength concrete within the seals of all intermediate pier foundations. Many voids within the seal concrete had become filled with silt. There was evidence of continued seal deterioration between underwater inspections.AHTD and its engineers considered three rehabilitation solutions in the preliminary engineering stage: micropiles, a cofferdam supported concrete jacket, or a pile supported concrete jacket. The three alternatives were estimated to cost $1,250,000; $4,320,000; and $3,030,000 respectively. All three options would transfer the loads from the pier footing directly to the rock below, bypassing the seal concrete."

Jan 1, 2007

By M Muzammil, S. Mukerjee, S. Saran, M. Bharathi

"This paper presents the results of in-situ tests conducted on a set of under-reamed piles in a silty sand deposit. Three piles (i.e. vertical, vertical with one bulb and vertical with two bulbs) of diameter 0.2 m were cast upto a depth of 5 m. The pile cap had four foundation bolts cast into it so that a mechanical oscillatormotor assembly could be mounted centrally on it. The oscillator-motor assembly was used to generate purely sinusoidal dynamic forces, in either horizontal or vertical directions. For both horizontal and vertical vibration cases, it was observed that (i) the natural frequencies decreased with an increase in the excitation force level, (ii) for the same excitation level, the natural frequencies as well as the maximum amplitude of vibration are almost the same irrespective of the pile geometry i.e. number of bulbs in the pile, indicating that the full pile length is not being excited. For the vertical vibration case, the soil-pile stiffness at frequencies, before resonance, were observed to be higher than those at frequencies after resonance. In the horizontal vibration case, the stiffness of the soil-pile system was found to be decreasing with an increase in the excitation force level. The damping ratio was found to be increasing with an increase in the excitation force level.INTRODUCTIONUnder-reamed piles are piles, normally upto a depth of 6 m, with one or more bulbs along the pile stem. These have been used for structures like transmission towers, structures on expansive soils etc. for a very long time, however it is only in the last 30 years that dynamic response of a pile has been studied. Evaluation of dynamic soil-pile interaction is a very complex problem as the conditions and properties of soil are highly variable and unpredictable. Various models and approaches have been suggested by various investigators for evaluating the dynamic soil-pile interaction problem, but most of them are based on the assumptions that the behaviour of soil is linear and the soil surrounding the pile is strongly adhered to it. But in practice, it is not so. The soil surrounding the pile is always somewhat loosened and undergoes some deformation when a sinusoidal load is applied. This causes the soil-pile system to behave nonlinearly.In earlier studies by Novak, (1974), Novak and Aboul-Ella, (1978) etc. a linear elastic behaviour of soil was assumed. This approach was very useful in understanding the mechanism of soil-pile interaction to a large extent. Subsequently various models were suggested like the lumped mass models with nonlinear discrete springs, dashpots and friction elements Matlock et al. (1978), weak cylindrical zone around the pile model Novak and Sheta, (1980), ideal boundary zone model with non-reflective interface, Han and Sabin, (1995) etc. These approximate solutions give an idea about the mechanism of dynamic pile-soil interaction to a large extent. However, in reality both separation and slippage can occur due to the formation of a weak bond at the contact surface between the soil and the pile when a dynamic load is applied. In addition, the soil column adjacent to the pile experiences large deformations under dynamic loads and thus behaves nonlinearly.Some computer aided model studies on the dynamic response of under-reamed piles have been reported, however, very few insitu dynamic tests on under-reamed piles are reported. Dynamic tests on piles were carried out by Novak and Grigg (1976) on small scale single piles and pile groups in the field. Similar field tests on small scale piles were conducted to study the nonlinear behaviour of a single pile and a pile group under strong harmonic excitation by Han and Novak (1988), Han and Vaziri (1992), Burr et al. (1997), Manna and Baidya (2010) etc. The majority of these experimental studies were focussed on the response of the specific pile groups and compared with the results of a single pile. Hence there was a need to study the influence of pile g"

Jan 1, 2015

By Jie-qun Zhai, Jian Jia, Ke Yang, Xiao-lin Xie, Yu Zhang

"With cities’ development, underground space exploitation presents a need for bigger and deeper constructions now. Technical problems founded during the construction of deep foundation pit support become more and more important. The supporting system has to cut or partly cut off hydraulic connection outside and inside the foundation pit, control the ground settlement caused by dewatering and make sure safety of foundation pit and its surroundings. Some preliminary study and application of ultra-deep soil reinforcement methods have been conducted in Shanghai’s deep excavation engineering. On the basis of engineering practice of ultra-deep foundation pit in Shanghai, some field and laboratory test, this paper analyzes effects of different ultra-deep soil reinforcement methods and their influence characteristics of surrounding environment. It also summarizes these methods’ sealing effect, construction and economic efficiency and concludes their characteristicsINSTRUCTIONShanghai is formed from marine sedimentation. In Shanghai, from earth’s surface to 30~40m underground, soil is mainly consist of soft clay with 40% moisture content. There are also many thin silty-sand layers in the earth, so the soil is both soft and permeable. Under 40m, soil is mainly thick silty-sand layers and fine-sand layers with medium density and confined groundwater whose water head is about 7m high.With the rapid development of Shanghai’s municipal construction and high-rise buildings in the recently ten years, the number of underground structure including subway station, tunnel and high-rise building basement are constructed rapidly. Due to the permeability and softness of Shanghai’s soil, it is necessary to reinforce soil to make sure the safety and high construction rate of engineering project in Shanghai.Because of deeper excavation depth and bigger excavation area in Shanghai, ultra-deep soil reinforcement is used preliminarily in Shanghai. Combining with engineering practice of ultra-deep foundation pit in Shanghai and employing field and laboratory test, this paper analyzes effectiveness of different ultra-deep soil reinforcement methods and concludes these methods’ characteristics and their applicability. All this can guide further application of these methods."

Jan 1, 2015

By James S. Graham

Marine design and construction methods are presented on the caisson foundations for the tower piers at the Brooklyn, Ben Franklin, Delaware Memorial 1st, Tappan Zee, Walt Whitman, Throgs Neck, Verrazano Narrows, Delaware Memorial 2nd, and Newport Bridges. All of the bridges are founded on caissons, bearing on bedrock, soil, or piling. Caissons at the Tappan Zee Bridge are partially supported by piling and partially by buoyant forces. General subsurface conditions for each are provided. The purpose of this paper is inform engineers how bridge foundations using caissons were built over major waterways in the Northeastern USA in the past, anticipating a surge of new bridge construction in the near future.

Jan 1, 2013

By Jahnavi Parmar, Pranav R. T Peddinti, Saloni Pandya, P. S. Prasad

Coastal cities are in desperate need of suitable land to meet the ever-increasing demand for urban infrastructure to support commercial, residential, tourism, and off-shore activities. Countries with a lengthy coastal line, such as India, possess significant areas of wide spread highly saline soils subjected to periodic seawater intrusion. One such soil stratum was encountered at the Gulf of Cambay, Bhavnagar district, Gujarat, India. Due to the high volume of river runoff, the Gulf has a positive water balance. The relative humidity ranges from 65 to 86 percent, making the climate semi-arid to sub-humid. The high salinity, mineral content, basaltic origin, and deeper water table offered the impetus to investigate applicability of various soil treatment options for such saline soils. Admixture stabilization techniques have been shown to help with problematic soil features. The Current study aims to determine effectiveness of addition of locally available lignite fly ash (10% - 30% by weight) and cement (6% - 9% by weight) to Bhavnagar saline soil in respect of strength, electrical conductivity and CBR. In this assessment, a comparison of stabilized and unstabilized saline soil mixtures is expected to highlight the need of understanding influence of treatment on instinctive performance of stabilized saline soils, as well as assist practitioners in efficacious treatment of extreme saline soils for diverse geotechnical and construction applications.

Sep 1, 2022

By Adrian Gygax, Sarah Gaib, Rod Kostaschuk

The British Columbia Ministry of Transportation and Infrastructure (Ministry) recently completed a slope stabilization project at Ten Mile Slide on Highway 99. The highway is an essential part of the road network connecting the British Columbia (BC) coast with the interior of the province. The landslide was first identified in the mid-1980s and has retrogressed more than 250 m upslope since then, leading to continual and expensive repairs to the highway. The Ministry engaged BGC Engineering Ltd. (BGC) and their structural sub-consultant Gygax Engineering Associates Ltd. (GEA) to develop a stabilization scheme that would halt the slide with an acceptable level of residual risk. The design required careful consideration of construction stages and the stresses induced in the structural components as the slide movement was progressively stopped as construction advanced. Four stabilization design options were shortlisted with the preferred option selected in Fall 2016. The selected solution comprised the construction of five rows of post-tensioned soil anchors upslope of the highway and a tied-back concrete tangent pile retaining wall for the roadway itself as well as reconstruction of the highway alignment, grade and drainage through the slide. Works were installed by top-down construction within defined time allowances stipulated in the contract. Significant engineering was undertaken beyond standard design processes for this complex project, such as comprehensive geotechnical investigations, aerial and terrestrial laser scanning and change detection analyses, pre-production test anchors, detailed geo-structural numerical modelling and due diligence activities to validate and optimize the design. The stabilization works have been very successful with the slide response being as predicted and the highway operating again as full two-lane service.

Oct 1, 2022

By Anburaj C., Srinivas A.

Deep excavation with support system is required to construct various part of underground structures like shafts, stations and entry structures etc. These structures have to be constructed using permanent or temporary embedded retaining walls with support system. The selection of a suitable type of retaining wall will depend upon the geological condition present in the particular location, time, cost and available equipment etc. In Bangalore Metro Rail Project, secant pile wall is adopted as the temporary earth retaining system and depth of excavation is about 20 m. It is designed initially based on bottom up construction methodology with 3 level of struts and 3 level of anchors but at later stage due to time and other construction related issues, it is decided to change the configuration to 6 levels of strut. Generally, in deep excavations, all the underground structures should be designed and checked for the critical forces from both permanent stage and construction stages. Since, secant piles are used as temporary retaining wall, only construction stage analysis is carried out to get the governing forces and deformation. In construction stage analysis, soil layers are defined with boundary conditions and the surcharge during construction and surcharge from actual building near the secant pile are considered. This paper discusses the effect of change in the support system from anchors to struts and how these changes in the support system affect the behavior of secant pile and subsequently adjacent buildings present in the influence zone of the excavation. As a result, in changing from anchors to struts, the wall displacement, strut forces and ground movement on the adjacent ground and buildings increases. The increase in deflection, ground movements and strut forces occurs during backfilling sequence of the underground station excavation. During backfilling, struts has to be removed and this imparts higher magnitude in deflection, strut forces and ground movements.

Nov 1, 2022

By Emilie Lapointe, Fernando Famania

"A reliable determination of the in-placed cement factor, as defined by mass of cement over volume of final element of treated soil, allows the optimization of cement usage to achieve treated soil requirements. Cement determination tests were performed on soil-cement samples, both fresh (as per ASTM D5982) and hardened (as per ASTM C1084). This paper reviews the calibration work required for the D5982 determination of cement content by the heat of hydration method used on soil-cement samples obtained by wet-grabbing. Using the correlation curves in the field provides a rapid assessment of cement content hence optimizing the cement injection rate to match laboratory tests previously conducted. Cement determination tests on hardened soil-cement specimens from wet-grabs and cores were performed using the oxides method. Samples, both cored and wet-grabbed, were tested in a given cement-treated element, and in different soils to inform on the expected variation in cement content from field installation. Results indicate that both cement determination methods are valid for forensically determining cement contents and that they provide better assessment than the conventional field reporting methods. The methods can be used to optimise the cement usage as well as for Quality Assurance, especially when coring quality is poor.INTRODUCTIONThe degree of improvement, and inherent strength, which is attained in a deep-mixed soil is a function of many factors. The binder type, the existing soil, the mixing conditions and the curing conditions are the categories of factors influencing the strength of a given cement-treated soil as agreed by the deep mixing community and as summarized by the Coastal Development of Technology [CDIT] (2012). Given a site with existing soils and conditions requiring soil improvement using a given binder, the designer and/or contractor can control the mixing conditions. Mixing conditions are inclusive of the degree of mixing, mixing duration and the quantity of binder. Once a deep mixing method has been chosen to mix optimally the in-situ soil, the quantity of binder is the only remaining factor to be optimized. The quantity of binder, in the construction industry is commonly referred to as the field binder factor [ar] and defined by the mass of binder over the volume of soil treated with kg/m3 as unit. In research, the quantity of binder is referred to as the binder content [Cc] and expressed as a ratio of the mass of binder over the mass of dry soil mixed."

Jan 1, 2015

By Siavash Mahvelati, Alireza Kordjazi, Joseph Thomas Coe

Deep foundations are often constructed as end bearing members with a significant amount of their capacity derived from bedrock. Sites with highly variable bedrock conditions therefore present a unique challenge when attempting to estimate the design elevation of deep foundations. Typical subsurface characterization techniques such as drilling, standard penetration testing (SPT), and cone-penetration testing (CPT) may fail to adequately establish top-of-rock elevation in geologic settings prone to karst and/or significant amounts of residuum, saprolite, and deformed bedrock. Seismic surface wave geophysical methods have been increasingly used to map bedrock topography in such settings. However, the current standard of practice for these methods introduces resolution limitations in spatially variable subsurface conditions due to averaging effects from the analytical framework used to process the acquired data. This study explores the use of a tomographic approach with full waveform inversion (FWI) to map top-of-rock elevations at a numerically simulated site representative of highly variable bedrock topography. Comparisons are made with seismic refraction (SR) and a dispersion-based multichannel analysis of surface waves (MASW) approach as more commonly used in geophysical subsurface investigations. The results highlight that FWI provides a superior estimate of top-of-rock topography than SR and MASW at a cost of a significant increase in the required computational resources and time.

Sep 8, 2021

By Siavash Mahvelati, Alireza Kordjazi, Joseph Thomas Coe

Deep foundations are often constructed as end bearing members with a significant amount of their capacity derived from bedrock. Sites with highly variable bedrock conditions therefore present a unique challenge when attempting to estimate the design elevation of deep foundations. Typical subsurface characterization techniques such as drilling, standard penetration testing (SPT), and cone-penetration testing (CPT) may fail to adequately establish top-of-rock elevation in geologic settings prone to karst and/or significant amounts of residuum, saprolite, and deformed bedrock. Seismic surface wave geophysical methods have been increasingly used to map bedrock topography in such settings. However, the current standard of practice for these methods introduces resolution limitations in spatially variable subsurface conditions due to averaging effects from the analytical framework used to process the acquired data. This study explores the use of a tomographic approach with full waveform inversion (FWI) to map top-of-rock elevations at a numerically simulated site representative of highly variable bedrock topography. Comparisons are made with seismic refraction (SR) and a dispersion-based multichannel analysis of surface waves (MASW) approach as more commonly used in geophysical subsurface investigations. The results highlight that FWI provides a superior estimate of top-of-rock topography than SR and MASW at a cost of a significant increase in the required computational resources and time.

Oct 1, 2021

By Anjana C. P, K. Ranga Swamy

The hilly regions of Kerala are severely affected by excess rainfall, causing tremendous damage due to landslides and slope failures. It is necessary to strengthen the existing slope profiles to prevent such disasters and avoid their risk to human lives and civil infrastructures. This paper studies the effect of micro pile to reinforce the slopes in Idukki district of Kerala, where slope failures are frequent. Three-dimensional slope stability analysis is carried out on slopes from the Idukki to obtain safety factor values using the MIDAS GTS NX program. The slope is fully saturated herein by taking the model's piezometric surface at the ground level to simulate high rainfall intensity. The critical slopes are then modelled with micro piles to analyze their effectiveness in improving the stability under static conditions. Different micro pile arrangements are considered, and a series of slope stability analyses have been carried out to obtain the optimum configuration with the required safety factor. The FOS values increased by more than 50% with micro piles for all the slopes. The optimum micro pile arrangement obtained for each slope shows that micro pile distribution between the toe and middle of the slope is an effective location for reinforcing slopes.

Sep 1, 2022

By Antonio Marinucci, Robin Mao

The new Hangzhou West Railway Station, which is currently in the early stages of construction, will be located in the city of Hangzhou, China. To accomplish the ambitious goals of the project, the construction work and station building was divided into three project areas. The original design utilizes 1,580 drilled shafts with diameters of either 800 mm or 1000 mm (32 or 40 inch) to support the new Station and its various ancillary structures. The drilled shafts will be tipped into the moderately weathered argillaceous siltstone a distance between 5 and 15 m (16.5 and 49 ft), resulting in an effective pile length ranging from 35 to 43 m (115 to 141 ft), respectively. For the first phase, approximately 550 production drilled shafts will be installed. Eight (8) sacrificial drilled shafts each with a diameter of 1000 mm (40 inch) were installed to a depth ranging from 50 to 57 m (164 to 187 ft), and were tested to confirm the design parameters used for the first phase, to evaluate the contractor’s installation means-and-methods, and to provide guidance whether redesign is warranted for the subsequent two phases. Bi-directional static load testing was performed using a donut-shaped Super Cell to apply unidirectional axial loads up to 13,200 kN (2,970 kip). This paper will describe the bi-directional testing and select results obtained therefrom. The axial compressive and uplift resistances determined from the testing verified that the available axial resistance of a single drilled shaft exceeded the minimum design requirements.

By Yan Lap J. Kan

"A waterfront stabilization system consisting of Deep Soil Mixing (DSM) columns, vinyl sheet pile fascia, and concrete flood walls supported on shallow footings was designed and constructed for a high-density waterfront development in Northern California. The project site is underlain by soft, compressible organic soil locally known as Bay Mud that has been capped with loose sand and imported fill. The waterfront stabilization system constructed at the site mitigates liquefaction, consolidation settlement and seismic potential slope deformation along the waterfront; the system was designed to reduce lateral displacements to tolerable amounts for the proposed structures. This paper presents the general design methodologies, construction challenges and quality control of this waterfront stabilization system.INTRODUCTIONUrban development in Northern California is fueling innovations in geotechnical engineering as more complex sites are developed. ENGEO Incorporated introduced a deep soil mixing technology from Japan to the US and designed a waterfront stabilization system for a high density waterfront development project in Redwood City, California. The approximately 12½-acre project site, as shown on Fig. 1, is surrounded by water on three sides, with an inner marina at the center of the site.The project site is located in the seismically active San Francisco Bay Area in California. The San Andreas Fault, the Monte Vista-Shannon Fault, the Hayward Fault and the San Gregorio Fault are major active faults located within 25 miles of the site. Once a former marshland with a major slough until the late 1950s, the site was reclaimed by placing imported fill over the native compressible clay deposits, locally known as Bay Mud."

Jan 1, 2016

By W. Morgan NeSmith

Drilled displacement (DD) piles often develop significantly larger unit shaft resistance values than other drilled or augered pile systems in coarse grained materials. Minimal vibration and limited spoil development are also associated with DD pile installation and these factors are frequently additional financial and/or environmental benefits of the system. The application of DD piles in North America dates to the mid-1990s and their use in the Midwestern United States has been significant, particularly in the past 10 years. The authors have collected an extensive database of DD pile performance in the United States. The alluvial and glacial deposits of the Midwestern U.S. provide conditions where drilled displacement piles perform very efficiently when compared to coastal and residual geologies. This paper presents a summary of the authors? experience regarding installation and performance of DD piles in the Midwestern U.S. Information presented includes summary presentations of DD performance across a range of site conditions as well as a discussion of the relationship of DD performance and installation effort in the Midwest as compared to other geologic settings in the U.S.

Jan 1, 2009

By Madhu. P, Srinivas. K

Measurement of thermal properties like thermal conductivity, thermal resistivity, heat capacity and thermal diffusivity for materials, it plays a crucial role in a wide range of various civil and electrical engineering projects, and many field applications like building’s basement, power generation, underneath soil heating, wastes from nuclear as well as thermal plants, and buried cables. Thermal conductivity of soil depends upon various geotechnical parameters such as type of soil, moisture content, particle size distribution, density, and compaction characteristics. Earlier studies, the measurement of thermal conductivity of soil by incorporating the heat source methods. Thereby expensive and time taken to conduct in laboratory as well as field measurements. The thermal conductivity is determined by fabricated probe and used in this work. Fabricated probe was calibrated with glycerin. The thermal conductivity of the soil increases as the water content and density increase because these factors are majorly influencing and water has a higher thermal conductivity than soil minerals, and grain to grain contact increases as density increases. therefore, Thermal conductivity is higher in coarser soils than in finer soils. The details regarding of this work as explained in this paper.

Sep 1, 2022

By Cory McElprang, Enamul Hoque, Aaron Thomas, Scott A. Jacobs

Crosshole Sonic Logging (CSL) only evaluates concrete on the inside of reinforcing cages leaving the outside unevaluated unless other types of testing are performed such as Perimeter Sonic Logging (PSL). While there have been some reports of PSL testing having accurately identified anomalies (e.g. Samtani et al 2005), experience by Case Foundation Company has indicated otherwise where false positives were determined with subsequent coring. Numerous cases of PSL false positives are presented as well as a study where a shaft was installed with both inside and outside tubes, and CSL and PSL data were compared. To date, there is very limited data published on perimeter sonic logging, or Gamma-Gamma Logging (GGL) with tubes on the exterior of drilled shafts. Several cases will be presented where false positives were experienced where PSL testing was performed. In addition, a direct comparison will also be presented where a shaft was installed with both tubes on the inside and outside where CSL and PSL data is compared. BRIEF HISTORY – CSL TESTING AND TUBES ON INSIDE The general procedure of Crosshole Sonic Logging (CSL) testing includes attaching tubes to the reinforcing cage to be able to send a transmitter in one tube and a receiver in another tube with which a sonic pulse is emitted from the transmitter and received in another tube. The time taken for the sonic pulse to travel between the tubes is measured and compared to expected values for the known distance between the tubes. Any increase in time from expected values indicates the sonic pulse traveled through a media other than homogeneous concrete such as objects in the path (spacer wheels, steel bracing, etc.), tube spacing, or soil inclusions. However, variations in arrival time can also result from differences in concrete density. The tubes have traditionally been placed on the interior of the reinforcing cage which protects them during hoisting and placement of the cage and reduces wave refraction caused by modulus of elasticity differences between steel and concrete. This allows the concrete within the interior of the reinforcing cage to be evaluated, but the concrete outside of the cage is excluded from traditional CSL testing. As a result, alternative integrity testing has been developed to not only provide different ways to evaluate the integrity of drilled shafts but to also address the issue of evaluating the concrete outside of the reinforcing cage. These alternative testing methods include Gamma-Gamma Logging (GGL), Thermal Integrity Profiling (TIP testing) and Perimeter Sonic Logging (PSL) which is similar to CSL testing but instead of the tubes placed inside the reinforcing cage, the tubes are placed on the outside of the reinforcing cage as shown in Fig. 1.

Jan 1, 2019

This specification, along with the drawings, encompasses all designs, materials, products, accessories, tools, equipment, services, transportation, labor and supervision, installation techniques, and testing procedures required for the installation of soil nail excavation support or earth retention systems. This is a Guide Specification designed to assist in the development of project specifications for soil nail excavation support and earth retention systems. This Model Specification is based on generally accepted industry standards but may require modification by the specification writer to accommodate unusual and/or unforeseen site and subsurface conditions and the particular circumstances of the project. Care must be taken to avoid internal inconsistencies. It contains language allowing for a Contractor-Designed Soil Nail Wall, which would be removed if the design is provided by the Owner (e.g. See Sections 1.2 and 4.1).

Jan 1, 2010

By Dr Karsten Galipp, Kai-Julian I. Hendler, Prof. Manuel G. Pinheiro, Dr Peter J. Bourne-Webb

With a share of approximately 11% of global greenhouse gas emissions, the construction industry contributes significantly towards climate change. This is why construction projects should not only be assessed on costs and technical solutions, but also on their carbon emissions. Life Cycle Assessment (LCA) is a tool which can quantify the environmental impacts of a construction project over its entire lifetime. The objective of this study was to determine the carbon footprint of three types of quay wall structures, namely sheet pile combi-walls, open piled decks and caissons using an LCA approach. Each of these quay walls were studied under the same boundary conditions, such as design life, ground conditions, dimensions, location and so on. The analysis showed that the sheet pile wall has the lowest carbon footprint whereas the open piled structure has the highest. Furthermore, it could be shown that the largest share of greenhouse gases (approximately 80%) is emitted during the production of construction materials. The transportation of materials and construction activities each contributed under 12% to total emissions. The sensitivity analysis showed that with innovative approaches, such as adapting the concrete mix design, the carbon footprint could be reduced by 26% to 40%.

May 1, 2022

By Allen B. Stanton, Parthiv Brahmbhatt, Michael Grimm, Stanley L. Worst

Constructing a circular shaft consisting of secant piles has its own complications which make it more difficult than typical drilled shaft construction. Add to that performing under low overhead powerlines and sitting inside of a 40-foot deep, 50-foot diameter shaft and it becomes more about logistics than the actual drilling. The complexities associated with the Romeo Arm Interceptor Segment 5 Lining project are the focus of this paper, delving into the details that made it work successfully.

Oct 1, 2022