Search Documents

By Jesús E. Gómez

Verification and production testing of soil nails requires debonding the upper section of the soil nail to isolate the portion of the soil nail intended for testing within a specific ground type. In pre-drilled soil nails, debonding can be accomplished relatively easily because the bar can be fitted with a debonding sheath before its installation. However, debonding of hollow core bar soil nails requires special procedures to achieve the intended result. This paper is a summary of the Federal Highway Administration (FHWA) Hollow Bar Soil Nail (HBSN) Test Program, which is described in detail in FHWA-CFL/TD-10-001. The program was developed to establish a suitable debonding procedure to test hollow core bars in soil nailing applications, and to initiate a database on typical bond values of HBSNs. The investigation showed that it is possible to debond hollow core bars for testing. It was also found that hollow core bars installed in granular soils may present ultimate bond values that are significantly higher than those typically used for design of conventional pre-drilled soil nails.

Jan 1, 2011

By Kaustuv Bhattacharya, Manish Kumar, Nirbhay Singh, Prodyot Kr. Ray, Praveen Soin

This paper highlights salient features of an excavation 38 m (Length) by 10 m (Width) by 24 m (Depth) carried out in Central Kolkata. Secant pile wall (SPW) formed using a combination of alternating 1200 mm & 800 mm diameter piles was used. Six layers of struts and waler beams, including bottom slab were utilized as lateral restraints to piles. The geotechnical profile for excavation zone was predominantly silty sand to sandy silt. The profile is characteristic of river channel deposit usually encountered in Kolkata. Temporary stage analysis (including seepage analysis) and design were carried out in FEM softwares. Design checks for clay bursting, piping, bottom heave, etc. were also carried out. Extensive instrumentation and monitoring were carried out during the excavation period to check parameters such as ground movement, pile movement, piezometric heads, etc. as per review levels. During excavation, ground improvement using Tube-a-manchette grouting technique was also required to be carried out as per field observations. The paper discusses some of the major challenges faced as well as measures taken to counter them, during deep excavation carried out in silty soils in a very congested Urban setting in the heart of a Megacity.

Sep 1, 2022

By Larry Rayburn

Augercast piles evolved in the late forties from the process of pressure grouting open holes backfilled with stone. In 1956, a patent was issued for a cast in situ pile by pumping high pressure grout through hollow-stem, continuous flight auger as the auger is gradually withdrawn from the ground. The patent rights expired in 1973 and the use of auger-cast piles greatly expanded with most large deep foundation contractors now installing augercast piles. At one time augercast piles had a bad reputation, partly because of not having a blow count to give some engineers a confidence factor and there were some quality issues. Over the years the quality issues have been eliminated and I am sure the augercast is the most installed pile in private industry and is now being used by some State Agencies.

Jan 1, 2005

By Reda Mikhail, M. Birkan Bayrak

The Washington State Department of Transportation (WSDOT) State Route (SR) 167/70th Avenue East Vicinity Bridge Replacement Design-Build project is located in Fife, Washington. This $40 million project consists of replacing the existing 70th Avenue Bridge over Interstate 5 (I-5) with a single-span bridge of about 220 feet long with approach embankments. The subsurface conditions along the new bridge alignment generally consists of alluvial deposits with high potential of liquefaction overlying glacially overridden deposits. In the early stages of the project, drilled shafts were considered as the deep foundation system; however, after an additional subsurface investigation is completed at the site, driven pipe piles were selected as the deep foundation system. Bridge abutments are supported by 24-inch diameter, 80-foot-long open-end driven steel pipe piles. The pile length was determined to bypass a relatively thick liquefiable zone and to tip the piles above what could be compressible soils. The use of advanced seismic analysis was instrumental in optimizing the pile length. The dynamic testing performed on numerous piles indicated what could be unique soil setup factors compared to those measured in local projects as well as those reported in national design manuals. Detailed discussions of the pile foundations design and construction is presented in this paper.

Sep 8, 2021

By Franz-Werner Gerressen, Manfred Schoepf

"Diaphragm walls are known as underground structural elements commonly used as retention systems for excavation pits and shafts and permanent foundation walls or elements. It can be anticipated that, with the increasing trend of utilizing more and more underground space to accommodate environmental considerations and urban/suburban development, there will be an increasing requirement for diaphragm walling in even more complex conditions. Complex and/or challenging conditions in terms of ground conditions have a major impact in regards of choosing the right tools for excavation purpose. Complex conditions in terms of space limitations, especially for inner city job sites, require specifically adapted solutions for slurry, spoil, reinforcement and concrete handling and the related logistic to ensure smooth production. Furthermore, one focus will be given to the QA/QC topics of the production process. Real time installation control, data transfer and reporting systems become more and more important ensuring the five dimensions of a jobsite. Therefore, the paper will describe the construction method and the sequence of activities required for the construction of diaphragm wall systems with the focus on the cutter technology. It will describe also the main equipment which will be needed to execute these works under the various conditions INTRODUCTION Diaphragm walls are known as underground structural elements commonly used as retention systems for excavation pits and shafts and permanent foundation walls or elements. It can be anticipated that, with the increasing trend of utilizing more and more underground space to accommodate environmental considerations and urban/suburban development, there will be an increasing requirement for diaphragm wall usage in even more difficult conditions. Of course diaphragm wall can also be used as deep groundwater barriers (Cut-Off-Walls). This market has shown that the demand for these types of walls is reaching more and more difficult soil conditions or required depths which are surpassing the current standard. The trench cutter is the most important tool for performing this work. The trench cutter itself is a reverse circulation excavation tool. It consists of a heavy steel frame with two drive gears attached to its bottom end, which rotates in opposite direction around horizontal axis. Cutter wheels are mounted onto the drive gears. As they rotate, the soil beneath the cutter is continuously being broken up, removed, mixed with the bentonite slurry in the trench and moved towards the opening of the pump suction box. The slurry loaded with soil and rock particles is pumped by a centrifugal pump which is located right above the cutter wheels, up through a hose system up to a desanding plant where the slurry is cleaned and returned into the trench."

Jan 1, 2015

By Dale Berner, Michael O’Sullivan

"This paper focuses on lessons learned from the innovative designs, in-the-wet construction methodology and modified foundation conditions, for two United States Army Corps of Engineers, USACE, Megaprojects:(a) The over $2 Billion Olmsted Dam across the Ohio River for the Louisville District; and(b) The $1.75 Billion Inner Harbor Navigation Canal, IHNC, Lake Borgne Hurricane Barrier in New Orleans for the Hurricane Protection Office, and the New Orleans District.Design innovations for the 24-inch dia. pipe pile foundation for the Olmsted Dam project include: (i) the use of controlled-fixity moment connections to the dam monoliths in order to tune the response of the dam under the 8.3 Richter scale seismic Maximum Credible Event, MCE; (ii) soil densification to inhibit liquefaction potential and (iii) design to facilitate underwater construction in a river with a highly moveable sand bed.Design innovations for 66-inch dia. concrete cylinder piles for the IHNC floodwall include: (i) the use of soil structure interaction, SSI, analyses to verify capacity to resist deep-seated failure plane in soft soil, while limiting lateral deflections to acceptable limits; (ii) the use of geo-fabric and scour stone for enhanced foundation response and (iii) design for ""in-the-wet"" construction on a fast-track basis.LESSONS LEARNED FROM THE INNOVATIVE OLMSTED DAM FOUNDATIONThe over $2Billion Olmsted Dam on the Ohio River is currently under construction 16 miles upstream from the confluence with the Mississippi River. It will consist of an 800-foot-long tainter gate section, a 1,400-foot navigable pass, two boat abutment sections, a fixed weir section, and upstream and downstream scour protection. The Olmsted Dam and its two, 1,200-foot locks, which were built in 2002, will eventually replace both Locks and Dam #52 and #53, both built in 1929, and thereby bring significant benefits to the Ohio River navigation system.In 2002, the Jacobs/COWI JV completed the design of the dam; which was an engineering challenge for several reasons, including:(a) Its proximity to the New Madrid Fault, could impose an 8.4 Richter Scale seismic event on the structure, which is located in an area of potentially liquefiable alluvium. The extensive seismic analysis performed by COWI included a response spectra analyses; lateral pushover analyses of pile foundations; hydrodynamic added masses; pile group effects; and the development of kinematic motions as a result of the soil-pile-structure interaction.(b) Maintaining vessel traffic along the river and accommodating fluctuating river elevations between 30-40 ft annually, and as much as 60 ft in a 100-year period.(c) Designing for the scour and uplift forces of artesian ground water and preserving a wildlife sanctuary on the Southern shore at the dam site."

Jan 1, 2017

By Pathik Deb Mallik, Shyamal K. Mitra, Rajiv Kishore, Shuvranshu Rout, Manos De

"This paper presents a case study on the design and construction of a deep underground pit structure constructed inside almost a century old existing plant building. The complexity and challenge for the design and construction lay in executing the work in a difficult subsoil condition especially the presence of deep mica schist. The limited space availability in the existing plant for construction work without hampering regular production in other adjoining areas of the plant made the execution more challenging. Experience with difficult subsoil and proximity to old foundations entailed a non-conventional engineering approach while ensuring complete safety in spite of maintaining the normal operation.INTRODUCTIONTata Steel Processing and Distribution Limited (TSPDL) is a subsidiary unit of Tata Steel Limited (TSL) having a CR processing facility inside the premises of Tata Steel Limited. TSPDL intended to install equipment for a new slitting line inside the existing shed including construction of very deep structure called “loop pit” where the strips from cut CR sheets collect in the form of loops and are recovered as scrap. The entire plant is located within the shed of existing plant. The construction of all foundations including the loop pit is to be executed in the limited area without disturbance to normal production work in balance areas of the plant and also maintain safety and integrity of existing structures.The existing shed is an old structure constructed approximately 80 years ago. The building column foundations are gravity type design of brick masonry supporting only the vertical load from the columns. This type of foundation designed with no eccentricity of loading provides no allowance for implementing any foundation stabilizing design. The present project required civil construction for the new equipment foundations safely within this area."

Jan 1, 2015

By Rajasekar Subbian, Jessica Oudhof

In the Netherlands pile foundation design is done using CPTs in accordance with EC7 national annexure. The capacity per tip level is calculated for every CPT followed by zonation to find the tip level per zone. The correlation factors are used to take into account the variability in ground across the zone and they depend upon the number CPTs within the zone. The CPTs and pile tip levels selection for zoning is an iterative process that can demand significant manual effort to produce an economical pile plan. This often leads to the use of conservative correlation factors in order to accelerate the design process. Thus, it has been automated in a tool with CPTs, pile location and loads, and capacities as input. The tool has also been employed in two case studies and the results are compared to the current design practise.

May 1, 2022

By Suthan Pooranampillai

Verification of drilled shaft resistance is primarily obtained through the use of different load testing methods. Procedures utilized include conventional top down static loading, the Osterberg load cell (O-cell) test and dynamic tests such as the Statnamic method. The O-cell test provides a means of obtaining separately the base and side shear resistance behavior of drilled shafts (cast-in-drilled-hole). Alternatively, the Statnamic load test method enables the engineer to derive base and side shear behavior separately, based on measurements of load, accelerations and strains along the length of the shaft. However, due to time and cost constraints these tests can only be performed on selected shafts within a project. Post grouting of a drilled shaft base embedded within a cohesionless material, with a low mobility compaction grout, will essentially pre-load the shaft base soil against the side shear and self-weight in much the same manner as an O-cell load test (when the load cell is placed within the base vicinity). Therefore, successful post grouting of a drilled shaft would enable verification of both shaft side shear and base resistance simultaneously on each and every shaft it is carried out on. Additionally, such post grouted shafts display stiffer load-displacement response during subsequent downward, superstructure induced, loading compared to ungrouted shafts. Verification of resistance on each and every shaft through the use of post grouting will allow an increase in resistance factors (reduction in safety factor) used in the design. Two 6 ft. diameter drilled shafts were constructed in Fredonia, WA, for WSDOT, each with an approximate length of 52 ft. The shafts were terminated within medium dense poorly graded silty sand. Statnamic load testing of the shafts indicated maximum derived static side shear and base resistances of 2545 kips and 507 kips (1.6 in. displacement) for shaft One and 2466 kips and 212 kips (1.4 in. displacement) for shaft Two. Shaft Two was subsequently grouted, with a low mobility compaction grout. Shaft base mounted total earth pressure cells measured a maximum sustained pressure of 55.44 ksf during the compaction grouting operation. Shaft displacement reached 0.65 inches in the upward direction at termination of grouting. Comparison of grouting data with initial load test information indicates that properly instrumented post grouting verifies shaft base and side shear resistance. In addition, these grouting induced resistances were much higher than design values supplied by the engineer using conventional resistance factor design. Large scale laboratory testing also shows that base grouting verifies higher soil resistances than permissible in conventional design.

Jan 1, 2010

By Javankhoshdel Yacoub

Piles are often used to reinforce slopes as they increase the available restoring force when calculating the factor of safety against sliding. In this paper, a 3D model of a slope containing multiple modes of failure is reinforced using pile elements. The results of the 3D Limit Equilibrium analysis containing piles are obtained using a newly introduced coupled approach which combines the results of finite element analysis (to obtain the displacement of soil along the pile) with the traditional limit equilibrium iterative formulation. The multiple modes of failure are obtained using the novel Multi-Modal Optimization (MMO) metaheuristic method which adapts the Particle Swarm Optimization (PSO) method to search for multiple local minima in a single slope model.

Oct 1, 2022

By Sowmiyaa. V. S., Tiruvengala Padma

Axial compression capacities of bored cast in situ piles as per Indian and International Standards are compared in this paper. Bored cast in-situ piles resting on soil and rock are considered for capacity assessment comparison. The standards considered for comparison are Indian Standards namely IS 2911-Part 1-Sec 2:2010 and IRC 78, International Standards like AASHTO LRFD Design-2017, API 2A WSD, BS 8004:2015 & EN 1997: Part 1:2014. The end bearing mobilization limits as proposed by various standards and their influence on longer piles in cohesive and cohesionless soils are discussed.

Sep 1, 2022

By Karen Dawson

This paper presents a case study of the deformation-based design, construction, and performance of stone column ground improvement (GI) beneath a mechanically stabilized earth (MSE) wall and bridge abutment with heights up to 50 feet. As part of the widening of Interstate 5 (I-5) to allow High Occupancy Vehicle (HOV) lanes in Tacoma, Washington, a new approach and span over the Puyallup River will be constructed. During the soils investigation and design phase of the project, low plasticity silts (ML) inter- bedded with silty sand layers and organic silt where identified as being potentially liquefiable. Stone column ground improvement was designed using a deformation-based approach to address static settlement and seismic stability of the proposed MSE embankments. The deformation-based design of the stone columns resulted in significant savings over a limit equilibrium-based approach. This paper presents the results of sonic coring taken from the initial stone columns installed and compares these results to the real-time data acquisition reports from the stone column installations. Vibration monitoring results during stone column installation are included. Settlement monitoring at the face of the MSE wall and buried vibrating wire settlement monitoring elements are presented and compared to the original settlement predictions.

By Inc. Pile Dynamics, Daniel S. Belardo, Marcus Galvan, George Piscsalko

Soil nails are often utilized as a temporary or permanent earth retention technique for slope stabilization and for excavation retention for existing or new structures. Soils nails are generally advantageous as installation is relatively rapid and they can be installed beneath existing structures and where site access for equipment is limited. Due to the typically small cross-section of these elements, the inability to inspect the holes prior to grouting/concreting, and the various installation techniques utilized, quality control for assessing the integrity along the entire length is limited. Currently, quality assurance is conducted by load testing to verify the pull out capacity after installation. The load testing is typically done on a small percentage of the total number of soil nails. This paper will provide the results of a demonstration where the new Non-Destructive Test (NDT) method Thermal Integrity Profiling (TIP) was used to access the integrity of several soil nails along their entire lengths. This TIP method has been successfully used for several years to assess the integrity in drilled shafts and ACIP piles. The TIP method assesses the integrity across the entire cross-section and can identify regions where bulges, necks, and insufficient grout/concrete are present. TIP testing can also help assure that the contractor's installation methods are adequate and consistent for the intended design. For the project presented, instrumented Thermal Wire were affixed to the centered tension bars prior to placement in the excavated shafts. Temperature measurements were recorded from the hydration energy generated after grout/concrete placement, capturing the entire heating cycle. Manufactured defects were installed on the center bar at multiple locations. The results and conclusion will be discussed as well as recommendations for future use.

Jan 1, 2017

By Emad Farouz, Ehab S. Shatnawi

"The increasing demand for small deformations and high-capacity drilled shafts without enlarging drilledshaft diameters has motivated the development and increasing use of a base grouting (BG) technique. This technique has been demonstrated to improve drilled-shaft capacity, especially for shafts tipped into loose cohesionless soils. Nevertheless, there remains considerable uncertainty in predicting the performance of base-grouted shafts, particularly for shafts tipped into cohesive soils. To date, there are only two documented design methods for estimating the axial geotechnical resistance of base-grouted shafts: Tip Capacity Multiplier (TCM) and Axial Capacity Multiplier (ACM) methods. A comprehensive test program was carried out during the design phase of the Wisconsin Zoo Interchange project to help optimize the flyover ramp’s foundation design. The test program included installing and testing one base grouted shaft and one ungrouted shaft at two sites with different ground conditions. Based on test results, it was concluded that prediction of the TCM method is well correlated with the measured values for both cohesive and granular soils; however, both methods tend to underestimate the axial resistance. Results also highlighted the importance of the base-grouting criteria in taking full advantage of the base grouting.INTRODUCTIONBase-grouted drilled shafts (BGDS), also known as post-grouted drilled shafts, consist of conventionally installed drilled shafts that contain access grout tubes placed within the shaft during construction. After installing the drilled shaft and achieving the pre-established concrete strength, grout is injected at the shaft tip through the access grout tubes to improve soil behavior around the drilled-shaft base. The tip grout injection improves the overall shaft capacity and reduces settlement through Densifying the in situ soils, compressing any debris left by the drilling process, preloading the soil beneath the tip to mobilize the shaft base resistance within service limits, increasing the tip area, and increasing the side resistance in the lower portion of the shaft."

Jan 1, 2016

By Ambarish Ghosh, Rituparna Dey, Indrajit Chowdhury

"In port and harbor facilities, jetties and cargo berth terminals are usually installed on piles that remain partially embedded in soil, while a part of it behaves as columns supporting top deck. Technology in vogue adapts a pseudo static analysis in computer where the top deck including piles are analyzed as an integrated system based on finite element method when the piles are modeled as beam elements, while the soil in which it is embedded is modeled as linear or nonlinear springs. Typical berthing force of the ship is considered as a pseudo static force where the dynamic characteristics of the force is taken into consideration by an equivalent impact factor and little study exists on the actual behavior of these type of piles under the transient shock due to berthing impact. Present paper proposes an analytical solution based on which one can compute the dynamic response of such jetty piles considering shear modulus of soil constant with depth. Considering the solution is analytical in nature no special software is needed and can well be adapted fordesign office practice using generic utility software like MATHCAD, MATLAB etc. that makes theproposed model computationally very efficient.INTRODUCTIONResponse of piles under dynamic load has been an important study in the realms of civil engineering, where significant research has been carried out on its dynamic behavior under harmonic loads like one experienced in a machine foundation or under seismic force.A number of researchers have given solution to this problem like Parmelee et al (1964), Tajimi (1966), Penzien (1970), Novak et al (1974, 1983), Banerjee and Sen (1987), Dobry and Gazetas (1988),Chowdhury and Dasgupta (2008).However, most of these theories are based on piles loaded under harmonic load and valid for long piles where structural failure precedes the soil failure considering the piles are long and flexible."

Jan 1, 2015

By Jason Buenker, Molly Winston

Torque-installed piles are gaining popularity in Southern California as the go-to deep foundation element for small- to medium-capacity loads in urban environments. The torque-installed pile is a displacement- based screwed pipe pile with a closed-end conical tip welded to the bottom of the pipe. Torque-installed piles are most efficient in loose to medium dense soils with high liquefaction potential. Where used properly, torque-installed piles can be installed faster, require less clean-up, and create less onsite vibration/disturbance than other pile alternatives. However, torque-installed piles are not applicable in all soil conditions and care must be used to apply the pile effectively in the correct subsurface environment. This paper will review current Southern California state-of-the-practice for torque-installed pile design and construction, potential roadblocks to successful installation, and available capacities from load tests. INTRODUCTION Torque-installed piles are a type of full-displacement screwed pipe pile originally developed in Southern California circa 2001 by Substructure Support, Inc. The pile is unique for its proprietary closed-end conical tip shown in Fig. 1. The tip has a welded steel-helix plate and cutter teeth that allow the pile to be advanced efficiently under applied torque and down pressure (crowd). Since original development of the pile, several contractors or manufacturers have proposed similar proprietary screw-type piles with comparable conical tips. Pile installation is relatively quiet, vibration-free, does not generate spoils, and faster than comparable pile types. The pile was originally developed as an alternative to driven pile foundations and remains a critical substitute to driven foundations in urban environments. Torque-installed piles are conventionally specified as 12 ¾-inch outside diameter (OD) steel pipes with a ⅜-inch-thick wall, although larger sizes with alternative dimensions have been used outside Southern California. Pile installation lengths generally range from 30 to 50 feet but may reach 80 feet or greater where soil conditions permit. The pile is generally backfilled with concrete following installation to increase lateral pile stiffness and may incorporate rebar cages or other reinforcing steel to facilitate connections to structural elements. The pile is frequently specified using performance-based specifications that encourage contractor innovation and use of proprietary installation means and methods.

Jan 1, 2019

By Ke Yang

"Drilled shafts are typically used to support structures subjected to large moments at the shaft head. The large moment can produce push and pull forces on the two sides of a drilled shaft. Consequently, the applied moment is partially resisted by the push-pull moment resistance induced from the vertical side shears. This type of push-pull resistance has not been fully recognized in most design and analysis methods. In this paper, a 30 finite element model for a drilled shaft subjected to lateral load and moment is presented and is validated against two field lateral load tests. Based on the 30 finite element model, a parametric study is carried out. It shows that the push-pull moment can resist 18-35% of the applied moment. The parametric study also shows that the push-pull resistance varies linearly with loading eccentricity when the eccentricity is less than the shaft embedment length. A method to estimate the push-pull resistance is proposed based on the results of the parametric study. Then, a new method for lateral capacity prediction is proposed to account for the push-pull resistance. The base shear resistance is significant for short drilled shafts; therefore it is also included in the proposed method. A case study on four lateral load field tests illustrates that the new method could improve the accuracy of lateral capacity prediction when compared with the traditional Broms method.INTRODUCTIONDrilled shafts are typically used to support a variety of structures subjected to large moments. Sound walls, highway signs, traffic signals, high-rise buildings, electrical transmission towers, and bridge piers are examples of cases where lateral loads with large eccentricity would result in high overturning moments on foundations.Current analysis methods for capacity predictions (Broms, 1964a and 1964b; Brinch Hansen, 1961) or deflection predictions (Reese, et al. 197 4) of laterally loaded drilled shafts are based on the lateral resistance of soils and rocks. However, O'Neill pointed out that moments can be partially resisted through the push-pull resistance provided by the vertical side shears due to the rotation of the pile (Reese, 1997)."

Jan 1, 2005

By A. C. Ackenhell

The geologic environment of Pittsburgh, Pennsylvania is both inviting and challenging to drilled pier installation. The shales and clayey soil zone of the hills are favorable but the alluvial soils of the three major rivers create problems. Beginning in the early 1950's, drilled pier installation continually improved as methods were developed to meet the geologic challenge. Case histories are presented to illustrate the historical development of piers in Pittsburgh. Recent innovations reducing the groundwater problem are illustrated by a case history of a high rise building construction. Load test information for side wall shear on the cylindrical shaft area between the concrete and bedrock continues to be desired but remains generally uneconomical.

Jan 1, 2010

By Masaki Kitazume

"Many earthquakes take place every year in Japan, in which the 1995 Hyogoken-Nambu earthquake and the 2011 Tohoku earthquake induced both a humanitarian crisis and massive economic impacts. As liquefaction which occur in a loose and saturated sand layer, induces quite large damages of infrastructures, the importance of liquefaction mitigation has been emphasized to minimize earthquake disasters for many years. Many kinds of ground improvement techniques based on various improvement principles have been developed for earthquake disaster mitigation. Among them, the grid type deep mixing method has been often applied to liquefaction mitigation. In the method, the stiff grid walls are constructed by mixing the soil and binder in-situ, which are expected to restrict the shear deformation of the soil within the grid walls so that the pore water pressure generation can be remained small. The high applicability of the method was confirmed in several earthquakes, including the 1995 Hyogoken-Nambu earthquake and the 2011 Tohoku earthquake. In this paper, the development of the method, some applications of the deep mixing method to earthquake disaster mitigation are briefly introduced. INTRODUCTION In Japan, many earthquakes take place every year in Japan, in which the 1995 Hyogoken-Nambu earthquake and the 2011 Tohoku earthquake induced both a humanitarian crisis and massive economic impacts. As liquefaction induces quite large damages, the importance of liquefaction mitigation has been emphasized to minimize earthquake disasters for many years. Table 1 shows the amount of damage to port facilities (Noda, 1991). According to the table, the amount of damage when liquefaction takes place is about 20 to 50 times larger than that without liquefaction. This highlights the importance of liquefaction mitigation to minimize earthquake disasters. There are many kinds of soil stabilization techniques developed for liquefaction in Japan. Among them, the deep mixing method (DMM), an in-situ cement stabilization techniques, was developed in 1970s in Japan and has frequently been applied to improvements of clayey and sandy soils (Kitazume and Terashi, 2013). The grid type DMM has been often applied to prevent liquefaction, where the grid of stabilized column walls function to restrict generation of excess pore pressure in the soil within the walls by confining the soil particle movement. The improvement effect of the method was first evaluated in the Hyogoken-Nambu earthquake in 1995 and was also evaluated in the Tohoku earthquake in 2011. In this paper, some successful performance of the deep mixing method to earthquake disaster mitigation in the two earthquakes are briefly introduced."

Jan 1, 2015

By Diego Bellato

Production data recorded by special foundation rigs during construction activities at the site are commonly used for quality assurance / quality control procedures and, in particular, to prove that the installed foundation elements comply with the geometrical and quality requirements defined in the design specifications. Parameters such as crowd force, penetration/withdrawal rate, rotational speed etc. are usually presented in reports in the form of depth and/or time profiles. This type of protocols are already standard QA/QC solutions for ground improvement methods like deep soil mixing or jet-grouting, but they are quite rarely applied in combination with other techniques like diaphragm walls or Kelly drilling. In the latter cases, one of the main reasons behind this lack of site documentation is related to the difficulty in interpreting huge amount of data collected during the creation of single elements, which, in some cases, can last several days (not always in a row). In addition, the building sequence is often characterized by many alternated operations involving different movements of the rig and the use of different tools. In this context, the identification of specific construction activities based only on the mere exam of the time profiles of the recorded production parameters is extremely difficult. In this paper, the time profiles of production parameters obtained from a fully-cased Kelly drilling rig employed on a site in Karlsruhe (Germany) have been investigated and compared with a detailed series of activities deduced from a video filmed during installation. Typical time profile patterns associated to specific procedures have been identified by combining the different information available. The outcome of this study helped project engineers to automatize the recognition of activities directly from production data and led to an overall understanding and optimization of the construction process. INTRODUCTION The special foundation industry is characterized by the use of highly sophisticated machinery for the realization of geotechnical systems such as piled rafts, retaining walls and slabs for excavation pits, cut-off walls for levees and embankments or ground improvement solutions. Rigs can vary in size, weight, and power and can be provided with several drilling tools to cope with the different soil conditions (e.g. clay, sand, rock) and the different geometries of the elements to be built at the site (e.g. micro-piles, large- diameter bored piles, diaphragm walls, anchors). Due to the challenging construction procedures, various types of sensors have started to be mounted on the equipment in the last decades to monitor the behavior of some important machine parameters and to inform rig operators about the on-going process and the status of their devices.

Jan 1, 2019