skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


Title: Axial Load Capacity Predictions of Drilled Displacement Piles With SPT- and CPT-based Direct Methods
Drilled Displacement Piles (DDP) provide an ideal foundation solution that combines the benefits of ground improvement with traditional advantages of piling systems. This paper offers insights gathered from 55 construction projects in which nearly 130 DDPs were installed and tested axially. High quality site exploration data (e.g., Cone Penetration Test (CPT) and Standard Penetration Test (SPT)) were evaluated to derive geotechnical analysis parameters. The test sites consisted of mostly mixed soil types with strongly stratified layers of sand, silt, and clay. Pile diameters ranged between 35 and 61 cm (14 to 24 inches). Prior to analyzing the axial performance of DDPs, a variety of failure interpretation methods were assessed to confidently extrapolate failure loads when field testing was terminated prior to pile failure. Results of this study suggested the Van der Veen’s (1953) method to most closely estimate the load that triggers pile plunging behavior specific to DDPs, followed by the Butler & Hoy (1977) and L1-L2 methods (Hirany and Kulhawy, 1989). Hereafter, in-situ axial load test results were compared with a wide range of analytical methods, including those developed specifically for DDPs. Predictive accuracy was assessed in terms of total pile capacity and pile settlement and separated based on pile diameter, stiffness, and soil type. Most examined analytical methods underpredict the in-situ pile capacities for both, CPT and SPT -based analysis. It was also found that the difference between the experimentally determined and predicted capacities is related to the level of improvement in the surrounding soil following pile installation. A general comparison between predictive axial accuracy and the observed level of ground improvement is also discussed for sandy and mixed type of soils.  more » « less
Award ID(s):
1752303
PAR ID:
10397378
Author(s) / Creator(s):
Date Published:
Journal Name:
DFI Journal The Journal of the Deep Foundations Institute
Volume:
16
Issue:
2
ISSN:
1937-5247
Page Range / eLocation ID:
1 to 22
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; ; (, IFCEE 2021: Installation, Testing, and Analysis of Deep Foundations)
    El Mohtar, Chadi; Kulesza, Stacey; Baser, Tugce; Venezia, Michael D. (Ed.)
    Piles socketed into rock are frequently utilized to carry large loads from long-span bridges and high-rise buildings into solid ground. The pile design is derived from internal shear and moment magnitudes following code recommendation and numerical predictions. Little experimental data exist to validate code prescriptions and design assumptions for piles embedded in rock. To help alleviate the lack of large-scale test data, the lateral response behavior of three 18-in. diameter, 16 ft long, reinforced concrete piles was evaluated. The pile specimens were embedded in a layer of loose sand and fixed in “rock-sockets,” simulated through high strength concrete. The construction sequence simulated soil-pile interface stress conditions of drilled shafts. The pile reinforcement varied to satisfy the internal reaction forces per (1) code requirements, (2) analytical SSI predictions, and (3) structural demands only. The pile specimens were tested to complete structural failure and excavated thereafter. Internal instrumentation along with crack patterns suggested a combined shear-flexural failure, but do not support the theoretically predicted amplification and de-amplification of shear and moment forces at the boundary, respectively. 
    more » « less
  2. (, Geo-Congress 2020: Geotechnical Earthquake Engineering and Special Topics)
    J.P. Hambleton, R. Makhnenko (Ed.)
    The objective of this study is to develop a consistent relationship between small strain shear wave velocity (Vs), corrected cone penetration test (CPT) tip resistance (qc1Ncs), and corrected standard penetration test (SPT) blow count (N1,60cs) for liquefiable soils. In the absence of actual measurements of Vs in the field, it is common to use data from SPT or CPT testing to estimate Vs. However, empirical correlations between pairs of these in situ metrics can yield significantly different values of Vs. Using recent correlations between cyclic resistance ratio normalized to M7.5 (CRRM7.5) and Vs normalized to one atmosphere of overburden (Vs1), qc1Ncs, or N1,60cs, a consistent relationship is developed such that reasonably similar values of Vs can be obtained using either qc1Ncs or N1,60cs. In comparison to two published Vs correlations, the correlations given in this study provide an average Vs value when using N1,60cs as the dependent variable but a slightly lower prediction of Vs when using qc1Ncs as the dependent variable. 
    more » « less
  3. (, Proc. 3rd Intern. Conf. on Performance-Based Design in Earthquake Geotechnical Engineering (PBDIII))
    Cone Penetration Test (CPT) based simplified liquefaction evaluation procedures offer significant advantages over variants based on alternative in-situ test indices. However, the main drawback of CPT-based variants is that soil samples are typically not recovered during CPT sounding, and as a result, soils are often not characterized directly or tested further in the laboratory. The need thus arises to infer soil properties from CPT indices without physical confirmation. Utilizing an unprecedented database of field and laboratory test data from Christchurch, New Zealand, this study proposes deterministic and probabilistic correlations relating the soil behavior type index (Ic) to liquefaction susceptibility as defined by published criteria. The findings show that Ic can be used with reasonable accuracy as a proxy for laboratory index-test based criteria for assessing liquefaction susceptibility. Additionally, to assess liquefaction hazards in a fully probabilistic manner, the uncertainty of Ic for defining liquefaction susceptibility can be accounted for using an approach similar to that used to create fragility functions for performance-based earthquake engineering. The approaches used herein to develop deterministic and probabilistic Ic relationships for liquefaction susceptibility are not limited to soils from New Zealand, but rather, can be applied worldwide. 
    more » « less
  4. ; ; ; ; ; ; (, Canadian Geotechnical Journal)
    The cone penetration test (CPT) is one of the most popular in situ soil characterization tools. However, the test is often difficult to conduct in soils with high penetration resistance. To resolve the problem, a rotary CPT device has recently been adopted in practice by rotating the rod to increase the penetrability, particularly in deep dense sand. This study investigates the underlying mechanism of the rotation effects from a micromechanical perspective using models based on the discrete element method. With rotation, the cone penetration resistance ( qc) decreases by up to 50%, while the cone torque resistance ( tc) increases gradually. These results are also used to successfully assess existing theoretical solutions. The mechanical work required during penetration is observed to keep rising as the rotational velocity increases. Microscopic variables including particle displacement and velocity field show that rotation reduces the volume of disturbed soil during penetration and drives particles to rotate horizontally, while contact force chain and contact fabric indicate that rotation increases the number of radial and tangential contacts and the corresponding contact forces, forming a lateral stable structure around the shaft, which can reduce the force transmitted to the particles below the cone, thus decreasing the vertical penetration resistance. 
    more » « less
  5. ; (, 4th International Conference on Performance Based Design in Earthquake Geotechnical Engineering)
    Wang, L.; Zhang, J.-M.; Wang, R. (Ed.)
    Observations of the dynamic loading and liquefaction response of a deep medium dense sand deposit to controlled blasting have allowed quantification of its large-volume dynamic behavior from the linear-elastic to nonlinear-inelastic regimes under in-situ conditions unaffected by the influence of sample disturbance or imposed laboratory boundary conditions. The dynamic response of the sand was shown to be governed by the S-waves resulting from blast-induced ground motions, the frequencies of which lie within the range of earthquake ground motions. The experimentally derived dataset allowed ready interpretation of the in-situ γ-ue responses under the cyclic strain approach. However, practitioners have more commonly interpreted cyclic behavior using the cyclic stress-based approach; thus this paper also presents the methodology implemented to interpret the equivalent number of stress cycles, Neq, and deduce the cyclic stress ratios, CSRs, generated during blast-induced shearing to provide a comprehensive comparison of the cyclic resistance of the in-situ and constant-volume, stress- and strain-controlled cyclic direct simple shear (DSS) behavior of reconstituted sand specimens consolidated to the in-situ vertical effective stress, relative density, and Vs. The multi-directional cyclic resistance of the in-situ deposit was observed to be larger than that derived from the results of the cyclic strain and stress interpretations of the uniaxial DSS test data, indicating the substantial contributions of natural soil fabric and partial drainage to liquefaction resistance during shaking. The cyclic resistance ratios, CRRs, computed using case history-based liquefaction triggering procedures based on the SPT, CPT, and Vs are compared to that determined from in-situ CRR-Neq relationships considering justified, assumed slopes of the CRR-N curve, indicating variable degrees of accuracy relative to the in-situ CRR, all of which were smaller than that associated with the in-situ cyclic resistance. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email