Behavior of Defective Cast in Place Piles

This paper deals with testing defected model piles in the soil in order to study their behavior. In this respect, the results of model pile tests are discussed either geotechnically or structurally according to the type of failure. Two parameters were studied in order to evaluate the general behavior of defective piles. These parameters include the defect location and the defect type for floating and end bearing pile. The results of the experimental work indicated that the critical case for floating pile is seen to be when the defect of (5%) at the first third of the pile length at which the decrease in the bearing capacity is about (21%), while the decrease in the bearing capacity is found to be (14%) and (10%), when the defect is at the middle and the lower third of the pile length, respectively. The decrease in the bearing capacity for floating pile is found to be (31%) and (21%) for void and neck defect, respectively, while the decrease in the bearing capacity for end bearing pile is found to be (43%) and (52%) for void and neck defect, respectively.

Analisis Fondasi Raft Pile Bangunan Tinggi Terhadap Struktur Bangunan Di Sekitar

Raft pile is an option for high rise building that has more than 30 stories on soft to moderate soil conditions. Either spun pile or bored pile can be used as the pile foundation. This study focuses on 34-story building that is constructed near electric rail train station, where the soil type is dominantly clay with average N-SPT 20 – 30, there is also thin layer of soil with N-SPT 60. The study compares two types of piles, 30 m depth floating pile and 32 m depth end bearing pile, where the raft thickness is 2 m. The study was conducted by calculating the bearing capacity and settlement with formulas based from correlations of N-SPT and the N-SPT data. Midas 3D also used to simulate the settlement of the building and settlement around the building. The results show that for bored pile with depth of 30 and 32 m respectively has settlement of 20,757 cm and 3,0475 cm while the settlement around the building consecutively is around 10 – 11 cm and 1,5 – 2 cm. Bearing capacity of bored pile with 30 m depth is around 1593,6779 – 5382,5954 kN while bored pile with 32 m depth is around 1978,9153 – 6021,3859 kN.Fondasi rakit merupakan salah satu pilihan yang dapat digunakan untuk bangunan tinggi lebih dari 30 lantai pada tanah kondisi lunak sampai sedang. Untuk jenis fondasi tiang dapat digunakan tiang bor atau tiang pancang. Dalam penelitian ini dilakukan studi fondasi bangunan 34 lantai yang didirikan dekat dengan stasiun kereta rel listrik di mana lapisan tanah dominan lempung dengan N-SPT rata-rata 20 – 30 dan juga ada nilai N-SPT 60 namun berupa lapisan tipis. Studi dilakukan dengan membandingkan dua jenis tiang yaitu tiang dengan daya dukung friksi kedalaman 30 m dan tiang dengan daya dukung ujung kedalaman 32 m dengan ketebalan fondasi rakit 2 m. Studi dilakukan dengan menghitung daya dukung serta penurunan menggunakan pendekatan rumus-rumus berdasarkan data N-SPT dan korelasi dari data N-SPT, juga dilakukan simulasi Midas 3D untuk mengetahui besar penurunan yang terjadi di sekitar bangunan. Dari hasil studi banding diperoleh penurunan fondasi tiang 30 m dan tiang 32 m berturut-turut sebesar 20,757 cm dan 3,0475 cm sedangkan penurunan sekitarnya diperoleh berturut-turut 10 – 11 cm dan 1,5 – 2 cm. Daya dukung yang diperoleh tiang 30 m berkisar 1593,6779 – 5382,5954 kN dan tiang 32 m berkisar 1978,9153 – 6021,3859 kN.

New Analytical Solutions for Longitudinal Vibration of a Floating Pile in Layered Soils with Radial Heterogeneity

Based on the theory of wave propagation in three-dimensional (3D) continuum, a new analytical approach for the longitudinal vibration characteristics of a floating pile in layered soils with radial heterogeneity is developed by employing a viscous-type damping model. Firstly, an analytical solution for the longitudinal complex impedance at the pile head is deduced by employing the Laplace transform and complex stiffness technique with the compatibility conditions of the pile and radially inhomogeneous surrounding soil. Secondly, a semi-analytical solution in the time domain is further acquired by using the inverse Fourier transform method. Furthermore, the corresponding analytical solutions are validated through contrasts with previous solutions. Finally, parametric analyses are underway to investigate the effect of radial heterogeneity of surrounding soils on longitudinal vibration characteristics of floating piles. It is indicated that the proposed approach and corresponding solutions can provide a more wide-ranging application than the simple harmonic vibration for longitudinal vibration analysis of a floating pile in soils.

An Analytical Solution for Longitudinal Impedance of a Large-Diameter Floating Pile in Soil with Radial Heterogeneity and Viscous-Type Damping

An analytical model is presented for solving the longitudinal complex impedance of a large-diameter floating pile in viscoelastic surrounding soil with radial heterogeneity and viscous-type damping, taking the effect of three-dimensional wave propagation of soil and lateral inertia of the pile shaft into account. The corresponding analytical solution for longitudinal impedance is also derived and validated via comparisons with existing solutions. The influences of the pile length, Poisson’s ratio of the pile shaft and the viscous damping coefficient, as well as the degree and radius of disturbed surrounding soil, on the longitudinal impedance of the pile shaft are examined by performing parametric analyses. It is demonstrated that the proposed analytical model and solution are suitable for the longitudinal vibration problem of a large-diameter pile and radially inhomogeneous surrounding soil, especially when the pile slenderness is low. In addition, the present solution can be easily degenerated to describe the longitudinal vibration problem relating to a large-diameter floating pile in radially homogenous soil or a pile with fixed-end supports.