Behavior of single pile in unsaturated clayey soils

مقدم أطروحة جامعية

Muhsin, Isra Muhammad

مشرف أطروحة جامعية

Salim, Nahlah Muhammad Nuri
Fattah, Muhammad Yusuf

الجامعة

الجامعة التكنولوجية

الكلية

-

القسم الأكاديمي

قسم هندسة البناء و الإنشاءات

دولة الجامعة

العراق

الدرجة العلمية

ماجستير

تاريخ الدرجة العلمية

2012

الملخص الإنجليزي

The general field of soil mechanics can be subdivided into that portion dealing with saturated soils and that portion dealing with unsaturated soils.

The differentiation between saturated and unsaturated soils becomes necessary due to basic difference in their nature and engineering behavior.

The mechanical behavior of partially saturated soils can be very different to that of fully saturated soils.

It has long been established that for such soils, changes in suction do not have the same effect as changes in the applied stresses, and consequently the effective stress principles is not applicable.

In this thesis, a pile foundation with (0.6 m) diameter and (12 m) length is embedded in fully saturated and partially saturated Iraqi soils, within Baghdad city.

The analysis was carried out using finite element method.

The partially saturated parameters were calculated using laboratory methods (i.e.

filter paper method), such as the H-Modulus function based on the soil water characteristic curve (SWCC) which was obtained through the program (Soil Vision), after identifying the basic properties of the soils.

Then, the SWCC is converted to relation correlating the void ratio and matric suction.

The slope of the latter relation can be used to define the H Modulus function.

The finite element programs SIGMA/W and SEEP/W are then used in the analysis.

Eight noded axisymmetric isoparametric quadrilateral elements are used for modeling both soils skeleton and pore water pressure.

A parametric study is carried out and different parameters are changed to study their effects on the behavior of partially saturated clay.

These parameters include the degree of saturation, depth of water table, shear strength of clay, negative pressure head, soil density, permeability function, volumetric water content function, and the unsaturated soil modulus (H).

This study includes the effect of partial soil saturation on the ultimate shaft resistance, and the adhesion factor (α) in piles for each depth of water table and degree of saturation.

The study reveals that when the soil becomes partially saturated by dropping water table at different depths with different degrees of saturation, the pile capacity increases.

It was concluded that the change in the water table level and the degree of saturation has a great effect on the behavior of partially saturated clay.

In this work, it is found that due to dropping of water table and contribution of matric suction (i.e.

negative pore water pressure), the pile capacity in partially saturated soil is approximately (3-5) times higher than the capacity of piles in the same soil under saturated conditions, A linear increase in the capacity of piles is obtained due to lowering of water table and non linear increase due to change in matric suction for the same depth of water table.

The increase in the pile capacity due to change of water table is greater than the increase due to increase in matric suction, and a great effect of partial soil saturation on the values of skin friction due to changing of water table and degree of saturation for the three soils, within Baghdad city Al-Rasafa region; namely, Sahat Al – Wathiq from depth (3.5 m), in this study referred to as (Rasafa 1), Bab Al – Muadham from depths (9.5 m, and 3.5 m) referred to as (Rasafa 2) and (Rasafa 3), respectively.

التخصصات الرئيسية

العلوم الهندسية والتكنولوجية (متداخلة التخصصات)

الموضوعات

• الطين
• ألومينوسيليكات
• الرواسب

• APA
• MLA
• AMA

لغة النص

الإنجليزية

نوع البيانات

رسائل جامعية

رقم السجل

BIM-419828