Innovative Method for Evaluating Drilled Shaft Foundations for St. Croix River Bridge

1998 ◽  
Vol 1633 (1) ◽  
pp. 84-93
Author(s):  
Michael W. O’Neill ◽  
Gary J. Person
Keyword(s):  
Drilled Shafts ◽  
Interface Roughness ◽  
Design Parameters ◽  
Lateral Stiffness ◽  
Test Results ◽  
Side Resistance ◽  
Major River ◽  
Load Tests ◽  
Drilled Shaft Foundations ◽  
A Site

To develop design parameters for axially loaded drilled shafts for the St. Croix River Bridge, a major river crossing at Oak Park Heights, Minnesota, load tests were conducted on half-scale sockets in the primary formation, the Franconia Sandstone, at a site on the west bank of the river. The test results were analyzed by using a procedure that considered dilatancy at the shaft-sandstone interface using the known normal, lateral stiffness of the rock, and several candidate interface roughness patterns. The normal stiffness was measured by splitting a short socket vertically with an Osterberg load cell, within the Franconia formation. The interface roughness patterns were varied until the load-deformation behavior of the axial socket test was matched. The production shafts will have larger diameters and will penetrate the formation to a shallower depth than the axial test socket. The lateral stiffness therefore was scaled to account for these effects, and the analytical method was used to determine values of side resistance that should be used for designing the production shafts.

scholarly journals Within-site variability and reliability of foundation designs based on load tests

2019 ◽  
Author(s):  
◽  
Andrew Z. Boeckmann
Keyword(s):  
Load Test ◽  
Test Results ◽  
Considerable Variability ◽  
Specific Load ◽  
Primary Input ◽  
Bayesian Techniques ◽  
Test Information ◽  
Load Tests ◽  
A Site ◽  
Site Variability

Probabilistic evaluations of the reliability of foundation designs based on site-specific load test information are somewhat limited in number. Published evaluations have generally relied on Bayesian techniques. A primary input for Bayesian analysis is within-site variability, which describes the variability of foundation resistance across a site. Within-site variability is attributed to geologic variation across a site and to differences in construction outcomes among foundation elements. Published evaluations have generally used a deterministic value of within-site variability wherein within-site variability is treated as a known parameter and is not subject to updating based on load test results. In contrast, probabilistic within-site variability treats within-site variability as an uncertain parameter with its own probability distribution that is updated based on load test results. Probabilistic within-site variability has not been applied commonly. This research examines differences in reliability outcomes between deterministic and probabilistic within-site variability. Analysis of micropile load test results from five different sites was used to develop a distribution of within-site variability. The resulting distribution is relatively variable (i.e. the value of within-site variability is, itself, variable), which demonstrates that there is, in fact, considerable variability and uncertainty in the value of within-site variability.

Situ Tests of Bearing Character on Large Diameter Deep Socketed Pile in Qingdao Gulf Bridge

2012 ◽  
Vol 178-181 ◽  
pp. 2501-2504
Author(s):  
Chun Lin He ◽  
Cheng Zhong Gong
Keyword(s):  
Large Diameter ◽  
Bridge Engineering ◽  
Test Results ◽  
Long Span ◽  
Long Span Bridge ◽  
Side Resistance ◽  
Load Tests ◽  
Bearing Characteristic ◽  
Side Friction ◽  
The Relationship

With the development of long-span bridge engineering and increase of load on construction, the piles which socketed in rock more than 5 diameters have been used in some bridge engineering. Based on the technique of Anchored piles method, the static load tests of large diameter and deep socketed piles had been carried out in Qingdao Gulf Bridge. The bearing characteristics of large diameter pile were analyzed, including the load displacement curves of test pile; the axial force; the relationship between side friction and displacement and the sharing ratio of side resistance and end resistance. Finally, the test results were compared with specifications, The results showed that the bearing characteristic of deep socketed piles was as same as the friction piles in this area; from the results of test the side friction of pile could be estimated lower in strongly weathering breccia area while the friction in strong- weakly weathered breccia was relatively close to the value of exploration reports. At the bottom of the pile, because the relatively displacement of pile-rock was small, the pile side resistance is relatively small. It could be seen that the estimate of bearing capacity was less than the test result, and the pile foundation was safety enough.

Evaluation of uplift interpretation criteria for drilled shafts in gravelly soils

2012 ◽  
Vol 49 (1) ◽  
pp. 70-77 ◽  
Author(s):  
Yit-Jin Chen ◽  
Tsu-Hung Chu
Keyword(s):  
Drilled Shafts ◽  
Load Test ◽  
Drilled Shaft ◽  
Specific Design ◽  
Interpretation Criteria ◽  
Interpretation Criterion ◽  
Gravelly Soils ◽  
Load Tests ◽  
Drilled Shaft Foundations ◽  
Shaft Failure

Representative interpretation criteria are examined in this paper to evaluate the capacity of drilled shaft foundations under axial uplift loading in gravelly soils. A large number of uplift shaft load tests for gravelly soils are used for analysis, and the interpretation criteria are applied to these load test data to establish a consistent uplift interpretation criterion. The statistical results show that the smaller the uplift displacement, the higher the coefficient of variation. In general, the displacements required to mobilize shaft failure load in gravelly soils are larger than those in non-gravelly soils. Based on these analyses, the relative merits and interrelationships of these criteria are established. Specific design recommendations for the evaluation of uplift drilled shaft capacity are given.

Field static load tests on drilled shaft founded on or socketed into rock

2000 ◽  
Vol 37 (6) ◽  
pp. 1283-1294 ◽  
Author(s):  
Caizhao Zhan ◽  
Jian-Hua Yin
Keyword(s):  
Bearing Capacity ◽  
Static Load ◽  
Large Diameter ◽  
Load Test ◽  
Drilled Shaft ◽  
Test Results ◽  
Static Load Test ◽  
End Bearing Capacity ◽  
Side Resistance ◽  
Load Tests

The Mass Transit Railway Corporation proposes to construct the Tseung Kwan O Depot (TKD) within Area 86 reclamation at Tseung Kwan O as part of the Tseung Kwan O Extension. The proposed foundation for the TKD comprises about 1000 large-diameter, bored, cast in situ, drilled shafts founded on or socketed into rock. To confirm the design allowable end bearing capacity and rock socket side resistance for the drilled shaft foundations, two test piles were constructed and tested. Both test piles were instrumented with strain gauges and rod extensometers. This paper presents the static compressive load test results on both test piles. The test results indicate that an end bearing capacity of 20.8 MPa (design allowable 7.5 MPa) and rock socket side resistance 2.63 MPa (design allowable 0.75 MPa) are achieved during the pile load tests with no sign of failure.Key words: drilled shaft, static load test, end bearing capacity, rock socket, rock socket side resistance, load transfer.

Geotechnical Resistances of Drilled Shafts in Triassic Basin Sedimentary Rocks

2021 ◽  
Vol 15 (1) ◽  
Author(s):  
John Turner
Keyword(s):  
Design Tool ◽  
Drilled Shafts ◽  
Late Triassic ◽  
Load Testing ◽  
Rift Basins ◽  
Base Resistance ◽  
Load Tests ◽  
The Common ◽  
Drilled Shaft Foundations

Load tests on drilled shaft foundations with rock sockets in sedimentary formations associated with various Triassic Basins in the Mid-Atlantic region show that some generalizations are possible for estimating geotechnical resistances. Axial load tests on drilled shafts in locations several hundred miles apart produce surprisingly similar results. The common feature is the geology: all of the load-tested rock sockets considered were constructed in sedimentary rock associated with one of the rift basins that developed in response to breaking apart of the supercontinent Pangaea that began during the late Triassic Period (about 220 million years ago) and coincided with opening of the Atlantic Ocean. More specifically, all of the tested rock sockets were in the ‘red bed’ facies of the rift basin sediments consisting of reddish-brown siltstone, sandstone, and shale. Each of the projects described herein and the associated load tests are described and used to illustrate fundamental principles of rock socket design and how load testing can be used as a design tool. The important role of quality construction, in combination with quality assurance through inspection and testing, is emphasized, especially as it relates to the evaluation of base resistance for rock socket design.

Lateral Performance of Drilled Shafts due to Combined Lateral and Axial Loading

2013 ◽  
Vol 29 (4) ◽  
pp. 685-693 ◽  
Author(s):  
C. J. Chien ◽  
S. S. Lin ◽  
C. C. Yang ◽  
J. C. Liao
Keyword(s):  
Axial Loading ◽  
Senior Author ◽  
Drilled Shafts ◽  
Lateral Loading ◽  
Bending Moments ◽  
Test Results ◽  
Pile Head ◽  
Head Displacement ◽  
Reverse Circulation ◽  
Load Tests

ABSTRACTThis paper reports the results of a series of full-scale drilled shaft load tests subjected to combined axial and lateral loading and lateral loading only. The tested shafts, 1.4m in diameter, were embedded 37m in sandy silt. All tested shafts were installed using reverse circulation method. The test results indicated, given the same lateral loading, 63% of pile head displacement resulted from combined load corresponded with the case of lateral loading only. The test results were compared to the numerical results of the software LPILE as well as the analytical solutions proposed by the senior author and his co-workers. The analytical results of the pile bending moments along shaft showed better results than that of LPILE.

Design of shallow rock-anchored foundations

1982 ◽  
Vol 19 (4) ◽  
pp. 463-471
Author(s):  
Nabil F. Ismael
Keyword(s):  
Transmission Lines ◽  
Design Parameters ◽  
Test Results ◽  
Design Procedures ◽  
Uplift Pressure ◽  
Rock Types ◽  
Rock Formations ◽  
Load Tests ◽  
Rock Anchors ◽  
Important Design

Full-scale uplift and lateral load tests were carried out on rock anchors and rock-anchored foundations at several sites in the Province of Ontario. Various rock types were tested, ranging from soft shale to sound limestone. The results are presented; they were analyzed and important design parameters were determined for different rock formations. Based on test results, simplified design procedures were developed for the convenience of the design engineer. Keywords: Anchors, rock, transmission lines, foundations, tests, loads, design criteria, uplift pressure.

scholarly journals Optimization Analysis of Settlement Parameters for Postgrouting Piles in Loess Area of Shaanxi, China

2019 ◽  
Vol 2019 ◽  
pp. 1-16 ◽  
Author(s):  
Zhijun Zhou ◽  
Shanshan Zhu ◽  
Xiang Kong ◽  
Jiangtao Lei ◽  
Tong Liu
Keyword(s):  
Compression Modulus ◽  
Summation Method ◽  
Cone Penetration ◽  
Optimization Analysis ◽  
Loess Area ◽  
Elastic Compression ◽  
Settlement Calculation ◽  
Side Resistance ◽  
Load Tests ◽  
The Relationship

The settlement calculation of postgrouting piles is complex and depends on the calculation method and parameters. Static load tests were conducted to compare the settlement characteristics of nongrouting and postgrouting piles, and three vital parameters in the layer-wise summation method were revised to predict the settlement of postgrouting piles. The elastic compression coefficient was deduced based on the Mindlin–Geddes method by considering the influence of the change in the pile side resistance distribution and end resistance ratio on the elastic compression after grouting. The relationship between the compression modulus and soil gravity stress and cone penetration resistance were established, respectively, using experimental data. The optimum value of the settlement empirical coefficient was determined using regional data. Finally, we used the postgrouting pile of the Wuqi–Dingbian expressway as a practical example. The results obtained from the layer-wise summation method after parametric optimization were close to the measured values. The results of this study provide reference data and guidance for the settlement calculation of postgrouting piles in this area.

Research on Static Load Tests of Damaged Bridge Strengthened with Pre-Stressed HFRP

2014 ◽  
Vol 1079-1080 ◽  
pp. 258-265
Author(s):  
Chen Ning Cai ◽  
Shan He ◽  
Li Na Liu ◽  
Shi Kun Ou
Keyword(s):  
Static Load ◽  
Flexural Rigidity ◽  
Fiber Reinforced Polymer ◽  
Test Results ◽  
Structural Members ◽  
Fiber Reinforced ◽  
Hybrid Fiber ◽  
Reinforced Polymer ◽  
Glass Fiber Reinforced ◽  
Load Tests

Thispaper presents an experimental study to strengthen an existing bridge usingpre-stressed carbon fiber reinforced polymer (CFRP) and glass fiber reinforced polymer(GFRP) materials. The method using pre-stressed hybrid fiber reinforced polymer(HFRP) to strengthened structural members is an emerging pre-stressed strengtheningtechnology. In this study, experimental data selected from result of staticloading test conducted to hollow slabs with CFRP/GFRP has been compared with specimenswithout strengthening. Test results showed that the strengthening methoddeveloped in this study could effectively reduce the stress in hollow slab,improving the flexural rigidity and inhibiting the concrete from fracture.

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