Axial response of piles in electrically treated clay

1999 ◽  
Vol 36 (3) ◽  
pp. 418-429 ◽  
Author(s):  
M Abdel-Meguid ◽  
M H El Naggar ◽  
J Q Shang
Keyword(s):  
High Voltage ◽  
Large Scale ◽  
Axial Loading ◽  
Soil Improvement ◽  
Pullout Capacity ◽  
Axial Capacity ◽  
Testing Facility ◽  
Load Tests ◽  
Pile Load Tests ◽  
Marine Clays

Improvement of the shear strength of soft clayey soils around steel pipe piles using high-voltage electrokinetics is investigated in the present study. The experimental setup of a large-scale testing facility is described. Four model piles were installed in two identical cylinders filled with simulated marine sediment. Five electrically insulated electrodes were installed close to the piles to apply a high-voltage electric field in the test cylinder. Negative direct current voltages of -20, -30, and -10 kV were applied in three phases, respectively, for 33 days in the treatment cylinder. Axial compression and pullout pile load tests were performed and the results were compared for both cylinders after each phase of treatment. The pile response is presented in terms of the experimental load deflection curves. It is observed that the axial capacity was increased 30, 29, and 8% after the first, second, and third treatment phases, respectively. The pullout capacity was increased due to the treatment by 11, 23, and 12% after the first, second, and third treatment phases, respectively. Further development of this technique may provide potential solutions for the improvement of soft marine clays, and ultimately it could be applied in the field to rehabilitate existing offshore foundations.Key words: electrokinetics, piles, marine clays, soil improvement, bearing capacity, axial loading.

Circular precast concrete manholes: experimental investigation

2011 ◽  
Vol 38 (3) ◽  
pp. 319-330 ◽  
Author(s):  
Reem Sabouni ◽  
M.H. El Naggar
Keyword(s):  
Large Scale ◽  
Precast Concrete ◽  
Technical Information ◽  
Experimental Program ◽  
Traffic Loading ◽  
Sanitary Sewer ◽  
Testing Facility ◽  
Load Tests ◽  
Geotechnical Testing ◽  
The University

Circular precast concrete manholes are widely used in sanitary sewer and storm water systems. The lack of detailed technical information on them and the conservatism of their governing codes and standards call for a detailed investigation on them. The main objectives of this paper are to evaluate the state of strains in the precast concrete manhole and state of stresses in the soil beneath the base to be used in developing enhanced guidelines for the design of their bases. Three full-scale circular precast concrete manholes, two 1200 mm in diameter and one 1500 mm in diameter, were tested in the large-scale geotechnical testing facility (LSGTF) at the University of Western Ontario. Only one 1200 mm manhole base was reinforced. Twenty seven load tests were performed on the manholes, which involved loads representing the Ontario truck loads incorporated in the Canadian Highway Bridge Code. None of the manhole sections tested in the experimental program experienced any cracks. The test results showed that traffic loading had a small effect on the pressure under the manhole base. All three specimens could withstand the critical Ontario truck loads, even the non-reinforced ones.

Use of the piezocone test to predict the axial capacity of driven and jacked piles in clay

1996 ◽  
Vol 33 (1) ◽  
pp. 23-41 ◽  
Author(s):  
Marcio SS Almeida ◽  
Fernando AB Danziger ◽  
Tom Lunne
Keyword(s):  
Key Words ◽  
Skin Friction ◽  
Penetration Test ◽  
Cone Penetration ◽  
Pile Capacity ◽  
Axial Capacity ◽  
Tension Tests ◽  
Load Tests ◽  
Pile Load Tests ◽  
Correlation Factors

Results of 43 load tests on driven and jacked piles performed at eight calyey sites have been back-analysed using piezocone test data. A method to evaluate the axial capacity of piles has been proposed in which the pile unit skin friction and the unit end bearing resistance are computed from the net corrected cone resistance, qnet. Correlation factors between piezocone and pile load tests were back-calculated using this approach. As most of the pile tests performed were tension tests, special emphasis was given to the evaluation of the pile unit skin friction. Key words: clay, pile, piezocone, cone penetration test, axial pile capacity, skin friction.

Development of Combined Pile-CPT Methods for Estimating the Ultimate Axial Capacity of PPC Piles Driven in Different Soil Categories in Louisiana

2020 ◽  
Vol 2674 (2) ◽  
pp. 313-327
Author(s):  
Murad Y. Abu-Farsakh ◽  
Mohsen Amirmojahedi ◽  
George Z. Voyiadjis
Keyword(s):  
Prestressed Concrete ◽  
Technical Committee ◽  
Estimation Accuracy ◽  
Pile Capacity ◽  
Resistance Factors ◽  
Axial Capacity ◽  
Load Tests ◽  
Pile Load Tests ◽  
Log Normal ◽  
The Individual

The cone and piezocone penetration tests (CPT, PCPT) have been widely acknowledged as useful in-situ testing tools for subsurface investigation, characterization of soil type, and evaluation of different soil properties. Because of similarity between the cone and pile, the evaluation of axial pile capacity was one of initial applications of the CPT/PCPT. A previous study conducted by the authors on 80 pile load tests of precast prestressed concrete (PPC) piles demonstrated that some pile-CPT methods are able to predict the ultimate axial pile capacity with better accuracy than other methods. These methods include: Schmertmann, De Ruiter and Beringen, Laboratoire Central des Ponts et Chaussées (LCPC), European Regional Technical Committee 3 (ERTC3), University of Western Australia (UWA), probabilistic, and University of Florida (UF) methods. The results of these seven pile-CPT methods were compared and their performance was examined for different soil categories where different percentages of pile capacity contribution is because of sandy layers. The log-normal distribution of the estimated to measured pile capacity for these pile-CPT methods was adopted to develop combined pile-CPT methods that optimize the estimation accuracy of axial pile capacity in different soil categories. Reliability analysis using Monte Carlo Simulation (MCS) was used to evaluate the resistance factors ( ϕ) and efficiency ( ϕ/ λR) of the individual and combined pile-CPT methods. Results of analysis of 80 pile load tests demonstrated the advantage of using the combined pile-CPT methods over the individual methods in relation to improving the accuracy of estimating the ultimate axial pile capacity and having better resistance factors.

Parameters of the Plasma of a Large-Scale High-Voltage Discharge in Air at Reduced Pressures

2019 ◽  
Vol 45 (6) ◽  
pp. 527-536 ◽  
Author(s):  
A. V. Strikovskiy ◽  
S. V. Korobkov ◽  
M. E. Gushchin ◽  
A. A. Evtushenko ◽  
I. Yu. Zudin
Keyword(s):  
High Voltage ◽  
Large Scale ◽  
High Voltage Discharge ◽  
Reduced Pressures

scholarly journals Analysis of Subsynchronous Torsional of Wind–Thermal Bundled System Transmitted via HVDC Based on Signal Injection Method

Energies ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 474
Author(s):  
Junxi Wang ◽  
Qi Jia ◽  
Gangui Yan ◽  
Kan Liu ◽  
Dan Wang
Keyword(s):  
Wind Power ◽  
High Voltage ◽  
Direct Current ◽  
Computer Aided Design ◽  
Large Scale ◽  
Electromagnetic Transients ◽  
Torsional Mode ◽  
High Voltage Direct Current ◽  
Operation Conditions ◽  
Signal Injection

With the development of large-scale new energy, the wind–thermal bundled system transmitted via high-voltage direct current (HVDC) has become the main method to solve the problem of wind power consumption. At the same time, the problem of subsynchronous oscillation among wind power generators, high-voltage direct current (HVDC), and synchronous generators (SGs) has become increasingly prominent. According to the dynamic interaction among doubly fed induction generators (DFIGs), HVDC, and SGs, a linearization model of DFIGs and SGs transmitted via HVDC is established, and the influence of the electromagnetic transient of wind turbines and HVDC on the electromechanical transient processes of SGs is studied. Using the method of additional excitation signal injection, the influence of the main factors of DFIG on the damping characteristics of each torsional mode of SG is analyzed, including control parameters and operation conditions when the capacity of HVDC is fixed. The mechanism of the negative damping torsional of SGs is identified. A time-domain simulation model is built in Electromagnetic Transients including DC/Power Systems Computer Aided Design (EMTDC/PSCAD) to verify the correctness and effectiveness of the theoretical analysis.

Large-Scale Production of Flexible, High-Voltage Hydroelectric Films Based on Solid Oxides

2019 ◽  
Vol 11 (34) ◽  
pp. 30927-30935 ◽  
Author(s):  
Changxiang Shao ◽  
Bingxue Ji ◽  
Tong Xu ◽  
Jian Gao ◽  
Xue Gao ◽  
...  
Keyword(s):  
High Voltage ◽  
Large Scale ◽  
Scale Production ◽  
Solid Oxides ◽  
Large Scale Production
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