Driven Concrete Pile Foundation Monitoring with Embedded Data Collector System
Florida Department of Transportation (FDOT) sponsored research performed at the University of Florida resulted in developing a wireless monitoring and real time static capacity estimate technology for driven piles. This new technology, Embedded Data Collector (EDC), uses two levels of instrumentation, embedded in the body of precast prestressed concrete piles near the head and tip. Strain and acceleration measurements obtained at these instrumentation levels during driving are sent wirelessly to a receiver in the field, and analyzed in real time to provide the operator with estimates of static capacity, stresses in the pile, transfer energy, damping factor, stroke height, and other relevant parameters used to evaluate the pile driving process and the driving system. The EDC system is currently undergoing phase one of a two phase field evaluation program planned by the FDOT to determine the level of reliability that can be anticipated by its use. The first phase consists of monitoring piles with EDC instrumentation and concurrently monitoring them with the Pile Driving Analyzer (PDA), given that there is ample data supporting the reliability of PDA. Measurements of strain and particle acceleration converted to force and velocity traces can then be compared between the two systems, along with the corresponding calculated magnitude of downward and upward traveling stress waves as they move along the pile at any point in time. Selected hammer blows recorded by PDA equipment are analyzed by means of signal matching software (CAPWAP) and the estimated static skin, end bearing, and total resistance obtained are compared against EDC static resistance predictions. The second phase of the evaluation will compare EDC estimates of static capacity against instrumented static load test results. The purpose of this paper, is only to present a summary of results obtained thus far in phase one, and compares EDC estimates of static capacity results with those from PDA and CAPWAP.
ESTIMATING DRIVEN PILE CAPACITIES DURING CONSTRUCTION
The research focused on both evaluating the accuracy of current and past dynamic predictions of static pile capacity, and improving real time assessment of total, skin and tip resistance of driven prestressed concrete piles during driving. Using the Load and Resistance Factor Design (LRFD) framework along with a database of over two hundred piles (static load test vs dynamic measurements), a number of former and current dynamic methods for estimating static pile capacity were evaluated. It was found that the newer methods resulted in a higher percentage of Davisson capacity available for design for a given probability of failure. Also, even though a number of older methods gave higher LRFD phi factors (due to conservative nature), they had a smaller percentage of Davisson capacity available for design due to their low accuracy (large scatter, i.e., high standard deviation). Field assessment (i.e., "real time") of pile capacity with the Pile Driving Analyzer (PDA) from stress wave theory with Case Damping Coefficient, Jc, was found to be one of the more accurate methods at both EOD (End of Drive) and BOR (Beginning of Restrike). Moreover, from statistics, it was determined that a 30% variation in Jc only changed the static pile capacity prediction by 10%. From the database, it was also found that both the static skin to tip ratio, as well as the Jc value could be correlated to the measured dynamic skin to tip ratio. Using 23 piles in the University of Florida - Florida Department of Transportation database, which had both static (load tests) and dynamic data, the proposed method performed equal or better than the CAPWAP (Case Pile Wave Analysis Program) approach. To reduce cost, time, as well obtain more real time dynamic data, a wireless digital instrumentation package was developed and field-tested at SR-54 over Cypress Creek in Florida. Referred to as WAP (Wireless Analysis of Piles), the system is composed of a wireless transmitter and analogue to digital converters with strain and accelerometer instruments, which are cast inside the top and bottom of the pile. The WAP signals at the top of the pile compared very favorably to the PDA traces (externally mounted instrumentation), as well as giving forces and displacements at the bottom of the pile. Due to costs ($300/unit), the WAP system makes it viable to instrument every pile.
Sinonasal undifferentiated carcinoma, or schneiderian carcinoma arising from an aspergillosis: a case history.
The sinonasal undifferentiated carcinoma or schneiderian carcinoma is a rare, malignant, aggressive tumour of the maxillary sinuses with an unknown aetiology. Its site and clinical symptoms can simulate chronic sinusitis, and radiographs suggest severe osteonecrotic-type destruction. Only histological and cellular investigations can confirm the diagnosis. We describe a 62-year-old woman with no previous medical or surgical history who presented with unilateral dental pain and chronic sinusitis. She was diagnosed with sinonasal carcinoma and had a hemimaxillectomy and radiotherapy.