Analysis of interaction inside the pile group subjected to arbitrary horizontal loading

Abstract

The analysis of pile groups subjected to horizontal loading in one of two orthogonal directions is a common problem in geotechnical engineering. However, the above analysis should sometimes be extended with the additional cases of horizontal loading, in arbitrary direction. Although the full scale experiments can provide the best insight into the above problem, they are expensive and therefore not feasible solution. Instead, numerical (i.e. finite element) analysis usually remains the ultimate tool for large scope studies. The main objective of this research is the improvement of the analysis methodology of pile group for the case of arbitrary static horizontal loading. Its influence is investigated numerically to check for the existence of the "critical" pile group configurations and soil conditions, that may lead to the failure of the foundation structure and superstructure itself. To reach the above objective, apriori sensitivity analysis of the considered problem and identification of the main problem parameters are conducted in the first phase. After that, series of complex 3D numerical models for laterally loaded pile group analysis have been generated using PLAXIS 3D. Model validation is done by the back-calculation of available experimental results. Parametric study of pile groups with various configurations under arbitrary horizontal loading is performed, with an emphasis on pile force distribution, bending response and pile group efficiency. Modelling and simulation processes and the optimization of the calculation time were improved using the originally developed codes in Python. The use of multiple computers was allowed by using the author’s scripts developed within the thesis. The above research resulted in thousands of numerical simulations, whose findings provided the improved design methodology of pile groups under arbitrary static horizontal loading.

Analiza ˇsipova u grupi izloˇzenoj horizontalnom optere´cenju u nekom od dva ortogonalna pravca je uobiˇcajen problem u geotehnici. Medjutim, navedena analiza ponekad se mora proˇsiriti dodatnim sluˇcajevima horizontalnog optere´cenja, u proizvoljnom pravcu. Iako eksperimenti na realnim konstrukcijama mogu pruˇziti najbolji uvid u navedeni problem, oni predstavljaju skupo (i samim tim neizvodljivo) reˇsenje. Umesto toga, numeriˇcka analiza (npr. primenom metoda konaˇcnih elemenata) obiˇcno postaje primarni alat za studije velikog obima. Glavni cilj ovog istraˇzivanja je poboljˇsanje metodologije za analizu grupe ˇsipova za sluˇcaj proizvoljnog statiˇckog horizontalnog optere´cenja. Njegov uticaj je razmatran numeriˇcki kako bi se utvrdilo postojanje "kritiˇcne" konfiguracije ˇsipova u grupi i uslova tla, koja moˇze dovesti do loma temeljne konstrukcije i samog objekta. Radi ostvarenja gore navedenog cilja, u prvoj fazi sprovedena je uvodna analiza osetljivosti razmatranog problema i identifikacija glavnih parametara problema. Nakon toga, generisane su serije sloˇzenih 3D numeriˇckih modela za analizu boˇcno optere´cenih grupa ˇsipova u PLAXIS 3D. Validacija modela izvrˇsena je povratnim proraˇcunom na osnovu dostupnih eksperimentalnih rezultata. Sprovedena je parametarska studija boˇcno optere´cenih grupa ˇsipova razliˇcitih konfiguracija, sa akcentom na raspodelu sila u ˇsipu, odgovor ˇsipa pri savijanju i efikasnost grupe ˇsipova. Postupci modeliranja i simulacije, kao i optimizacija vremena proraˇcuna, poboljˇsani su primenom originalnih programa u Python-u. Upotreba viˇse raˇcunara za proraˇcun omogu´cena je primenom autorovih programa razvijenih u okviru ove teze. Navedeno istraˇzivanje rezultovalo je u hiljadama numeriˇckih simulacija, ˇciji su rezultati doveli do poboljˇsanja metodologije proraˇcuna ˇsipova u grupi usled proizvoljnog statiˇckog horizontalnog optere´cenja.