Banca de DEFESA: MARILIA DANTAS DA SILVA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : MARILIA DANTAS DA SILVA
DATE: 27/02/2023
TIME: 14:00
LOCAL: Programa de Pós-Graduação em Engenharia Civil
TITLE:

Analyses of Piles Partially Embedded in Rock

KEY WORDS:

Piles partially embedded in rock. Bearing capacity. Dynamic and static test.

PAGES: 300
BIG AREA: Engenharias
AREA: Engenharia Civil
SUMMARY:

In the design of piles partially embedded in rock, the main factors that influence the strength and deformability of the rock and the transmission of loads from pile to rock are of utmost relevance to pile behaviour. Although useful, most empirical methods were developed by comparing limited databases from specific regions, presenting differences in geological conditions, drilling methods and other features. The research deals with a case of piles partially embedded in rock located in the West Zone of the Recife Metropolitan Region, in the town of São Lourenço da Mata, Pernambuco, Brazil. The rock mass consists of ancient deposits, formed mainly by granites of different compositions, gneiss and schists. The deposits have been intensely deformed by several superimposed tectonic processes. Rotative and percussive perforations identified what was considered a "rocky top" at depths ranging from the surface to 12.70 meters, and the first meters drilled in rock are always described as being of low quality, presenting low recovery, marked alteration and intense fracturing. The results of compressive strength were quite variable, ranging from 12.3 to 121.4 MPa, indicating that such values should be considered very carefully and should include other main parameters of the rock in the analysis, such as the discontinuities of the rocky massif. Some laboratory tests were carried out with the purpose of characterizing, classifying the rocky mass and estimating the load capacity of the piles, using the results of uniaxial compression resistance of intact rock, the main parameter for design. Results from 99 dynamic loading tests enabled comparison between the mobilized lateral and mobilized pile toe resistance, with the estimated capacity obtained from the design methods known in the literature (Rosemberg & Journeaux (1976), Horvath (1978), Meigh & Wolski ( 1979), Poulos & Davis (1980), Cabral & Antunes (2000), Rowe & Armitage (1987), AASHTO (1996), Zhang & Einstein (1998), España (2011) e Xu et al. (2020)). In the prediction, the lateral (shear) resistancedue to pile penetration in residual soil was also considered. Because failure was not reached in the dynamic tests, the estimated capacity was much higher than the mobilized resistance. The lateral resistance mobilized by the soil was between 28% and 35% of the total mobilized capacity. The design method from España (2011), Cabral & Antunes (2000) and AASHTO (1996) achieved the most consistent results compared to the mobilized capacity obtained from the dynamic loading tests. Five static loading tests indicated conventional failure loads greater than the mobilized resistancein the 99 dynamic tests. The static tests and some of the dynamic tests were also analyzed by the application of Massad's (1992, 1993) interpretation method. The model conceived by Massad was also applied by himself in several other publications. This mathematical model allows the separation of friction mobilized in soil and rock and toe resistance mobilized by the pile in rock, with distributions compatible with those obtained from CAPWAP analyses. As the tests did not reach the pile failure, parameters of deformability of the rock were retro-analyzed. The variability of the values of Young module found was in a wide range, as expected, due to the marked alteration and intense fracturing of the rock. Regarding the resistance mobilized by friction in the rock, as a function of the uniaxial compressive strength of the specimens extracted from the rocky material, no reliable correlations were obtained, which was justified by the high alteration and intense fracturing of the rock mass.

COMMITTEE MEMBERS:
Externo à Instituição - FRANCISCO DE REZENDE LOPES - UFRJ
Externo à Instituição - FAICAL MASSAD - USP
Externo à Instituição - PAULO GUSTAVO CAVALCANTE LINS - UFBA
Presidente - 1130440 - ROBERTO QUENTAL COUTINHO
Externo ao Programa - 1549099 - ROBSON RIBEIRO LIMA - UFPEExterno à Instituição - WILSON CARTAXO SOARES - UNIPÊ