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This paper presents the results from a pile load testing program for a bridge construction project at Chalmette, Louisiana. The load testing includes three 66-in. spun-cast post-tensioned open-ended cylinder piles and one 30-in. square prestressed concrete (PSC) pile driven at four different locations along the bridge site in clayey-dominant soil. Both cone penetration tests and soil borings/laboratory testing were used to characterize the subsurface soil conditions. All test piles (TP) were instrumented with strain gauges to measure the load distribution along the length of the TPs and to measure the side and tip resistances, separately. Dynamic load tests (DLT) were performed on all TPs at different waiting periods after pile installations to quantify the amount of setup (i.e., increase in pile resistance with time). Case Pile Wave Analysis Program (CAPWAP®) analyses were performed on the DLT data to calculate the resistance distributions along the TPs. A static load test was performed only on the PSC pile and statnamic load tests (SNLT) were conducted on both pile types. Design parameters such as the total stress adhesion factor, α, and the effective stress coefficient, β, were back-calculated. The α values ranged from 0.41 to 0.86, and the β values ranged from 0.13 to 0.29. The load test results showed that SNLT overestimated the tip resistance as compared with dynamic and static load tests. Moreover, the pile tip resistance was almost constant during the testing period, and setup was mainly attributed to increase in pile side resistance with time.

This paper presents a new approach of estimating pile setup starts from the end-of-drive (EOD) resistance by the use of a power function model followed by a log-linear function. Often pile setup is estimated using the Skov and Denver(in: Proceedings of the 3rd international conference on the application of stress-wave theory to piles, Canada, 1988) model, which requires knowing the pile resistance at a reference time (to). This requires additional effort for testing the pile at the reference time (to). This effort may cause delay in the foundation construction and thus increasing the cost of construction. Pile load testing program was conducted on seven 914 (36 in.) square close-ended prestressed concrete (PSC) test piles at the Caminada Bay bridge project in coastal Louisiana to develop a methodology to estimate pile setup effectively starting from EOD resistance. Several dynamic load tests (DLTs) were performed on each test pile, with waiting periods of 60 min to 55 days after installation, to measure the magnitude and rate of setup. Static load tests (SLTs) were also performed at the end of the load testing program to validate the results of dynamic load tests. The load testing results showed that the total resistance increased up to 12 times of the EOD resistances after 28 days from EOD. The Skov and Denver (1988) setup parameter “A” was calculated for each test pile using different initial reference times (to). The results showed that the setup parameter “A” was highly variable and uncertain for to less than 1 day. This paper proposes a new power pile setup model that can be used to estimate pile setup immediately after EOD to the initial reference time, to, which is usually 1 day for a log-linear model. The proposed model was validated using results from published case studies for various geological conditions, which shows that the results of the model effectively match the setup test results within a small tolerance.

Piles driven in cohesive soils usually experience a large increase in capacity over time, known as setup or freeze. This paper presents the field results of two test piles that were driven ...

Soil setup is defined as the increase in axial resistance of driven piles after end of driving (EOD). Very recently, over the last five years, the time-dependent increase in axial resistanc...

This paper investigates the effectiveness of Sand Compaction Pile (SCP) in improving the density characteristics of cohesionless soil. The performance of SCP for different pile spacing, pile arrangement such as triangular and square, and coarseness of bed materials on the degree of soil improvement is studied in a better-controlled laboratory environment rather than more variable field environment. A SCP miniature device and a miniature dynamic cone penetrometer (DCP) were designed and fabricated in the laboratory. Sand beds containing loose cohesionless soil were prepared in a fabricated tank by sand raining from the pre-calibrated height. The SCPs were installed using the miniature device on the sand bed by displacing soil in the lateral direction in order to densify the bed prior to pouring sand in the displacement holes. The data of DCP in terms of penetration index and field density were measured at various depths to obtain correlation parameters between DCP and relative density of soil. This correlation was used to determine the relative density of improved soil beds due to the installation of SCPs. The improved soil condition was measured in terms of a decrease in penetration index or an increase in the relative density of bed materials. Some of the major findings include: the rate of increase of relative density due to installment of SCP is similar irrespective of the coarseness of bed materials; smaller pile spacing compared to an optimum spacing causes insignificant soil improvement; the triangular pattern shows better soil improvement compared to the square pattern for a given pile spacing.

This paper presents the results from a pile load testing program for a bridge construction project in Louisiana. The testing includes two 54-in. open-ended spun cast concrete cylinder piles, one 30-in. open-ended steel pile and two (30- and 16-in.) square prestressed concrete (PSC) piles driven at two locations with very similar soil conditions. Both cone penetration tests (CPTs) and soil borings/laboratory testing were used to characterize the subsurface soil conditions. All the test piles were instrumented with vibrating wire strain gauges to measure the load distribution along the length of the test piles and measure the skin friction and end-bearing capacity, separately. Dynamic load tests were performed on all test piles at different times after pile installations to quantify the amount of setup with time. Static load tests were also performed on the PSC and open-ended steel piles. Due to expected large pile capacities, the statnamic test method was used on the two open-ended cylinder piles. The pile capacities of these piles were evaluated using various CPT methods (such as Schmertmann, De Ruiter and Beringen, LCPC, Lehane et al. methods). The result showed that all the methods can estimate the skin friction with good accuracy, but not the end-bearing capacity. The normalized cumulative blow counts during pile installation showed that the blow count was always higher for the PSC piles compared to the large-diameter open-ended cylinder pile, regardless of pile size and hammer size. Setup was observed for all the piles, which was mainly attributed to increase in skin frictions. The setup parameters “A” were back-calculated for all the test piles and the values were between 0.31 and 0.41.

Six instrumented static-load test piles driven at four different locations along the LA-1 highway alignment in coastal Louisiana provided the opportunity to study the soil-setup behavior in relation to the soil properties. The instrumented piles consisted of six square prestressed-concrete (PSC) test piles of different sizes and different lengths. Both soil boring and piezocone penetration tests (PCPT) were conducted at each test-pile location to characterize the subsurface soil conditions. The testing program consisted of performing dynamic-load tests (DLTs) at predetermined time intervals, followed by one static-load test (SLT) at the end. These piles were instrumented with vibrating-wire sister-bar strain gauges along their length. Case pile-wave analyses were performed on the DLT data to calculate the soil-resistance distributions along test piles. Design parameters such as the adhesion factor α and the effective stress coefficient β were also backcalculated. The α values ranged from 0.68 to 1...

This paper presents the field experimental results of static load tests (SLTs) and dynamic load tests (DLTs) that were conducted on instrumented prestressed concrete (PSC) test piles to characterize the pile setup phenomenon for individual soil layers along the piles' length. For this purpose, three PSC piles were driven at a bridge construction site in Lake Charles, LA, that were tested at different times after installation. The piles were instrumented with sister bar strain gauges to measure the load transfer along the piles' length, and pressure cells and piezometers to measure the total stress, effective stress and excess pore water pressure (PWP) with time and hence the setup for different soil layers along the piles' length. Multilevel piezometers were installed in the surrounding soil to evaluate the spatial distribution of excess PWP and to measure the influenced zone caused by pile driving. The load tests showed that the side resistance increased by 129 %, 99 %, and 91 % for the three test piles during the last load test. The case pile wave analysis program (CAPWAP) analysis of the DLTs and the load distribution plots from SLTs were used to compute the resistance of individual soil layers along the piles with time. The results showed that the soil layers with low undrained shear strength and high value of generated excess PWP exhibited higher amount of setup; while soil layers with low permeability and low coefficient of consolidation exhibited higher rate of setup compared to other soil layers. The results also showed that setup increased at a higher rate before the dissipation of excess PWP and the rate became much slower after the end of dissipation process. The dissipation of excess PWP (or consolidation data) was used to quantify the setup by its contributing factors (i.e., consolidation and aging effect). The results showed that a majority of setups was because of the consolidation effect. The results of multilevel piezometers indicated that the influenced zone because of pile driving was almost 3B (B = pile width) radial distance from pile face.

This paper examined the setup behavior of two 0.61-m (24 in.) test piles (with 44.2-m and 51.8-m lengths) that were installed within 3.05-m (10-ft) center-to-center or 5D (D = Pile Diameter) spacing. The piles were instrumented with strain gauges to measure the load transfer and setup per individual soil layers. The 44.2-m pile was installed 2 h after the 51.8-m pile. Several dynamic load tests (DLT) and one static load test (SLT) were conducted on the test piles to measure the increase in piles resistances with time. The effect of pile installation sequence on setup behavior was also investigated. The test results showed that both test piles exhibited significant increase in pile resistances or setup with time. However, the initial side resistance for the 44.2-m pile (installed 2 h later) was about half the side resistance for the 51.8-m pile; and the rate of side resistance increase with time for the 44.2-m pile was much higher than the 51.8-m pile. This behavior can be attributed to the sequence of pile driving in clayey soils. The driving of the 51.8-m pile caused the development of excess pore water pressure in the surrounding soils that affected the initial pile resistance and the setup rate of the 44.2-m pile. The CAPWAP analysis of DLT and the load distribution plots from SLTs were used to compute the resistance of individual soil layers along the piles’ length with time, which showed that clayey soil layers exhibited higher amount of setup compared to sandy-silty soil layers. The results of this study showed that the time, to, to when the setup curves become log linear with respect to time can be as early as 2 h after end of driving. The results of the testing program also indicated that the setup rate parameter “A” is independent of the depth.

An instrumented test pile was installed at the Bayou Zourie bridge reconstruction site as part of a Louisiana Department of Transportation and Development (LADOTD) research initiative to study the setup phenomenon of piles driven in Louisiana soils. Pile instrumentation included pressure cells to measure the total pressure at the pile face, piezometers to monitor the excess pore water pressure at the pile face, and “sister bar” strain gauges to measure the strain distribution along the pile. Additional instrumentation consisted of multilevel piezometers installed within soils at different locations/depths from the pile and accelerometers attached to the piles during dynamic load testing. A total of two static load tests and four dynamic load tests were conducted on the test pile. During the static load tests, the strains within the pile were measured by the strain gauges, which were used to calculate the distribution of load transfer along the pile. Both static and dynamic load tests demonstrated the increase in pile resistance with time (setup). Results of dynamic load tests confirmed that pile setup occurs at a logarithmic rate after the end of driving (EOD) and is mainly attributed to the increase in side resistance. Good correlation was observed in this study between the pile setup and the percentage of dissipated excess pore water pressure with time. The measured excess pore water pressure suggested that the surrounding soil, along the pile (within distance 2B), is significantly influenced during pile driving. Results indicated that the changes in side resistance are directly related to the changes in the horizontal effective stress acting on the pile face.