April 28, 2024
Bahman Niroumand

Bahman Niroumand

Academic Rank: Assistant professor
Address:
Degree: Ph.D in civil engineering
Phone: 09173717862
Faculty: Faculty of Engineering

Research

Title
Laboratory and analytical study of the load transfer mechanism and the tensile capacity of barbed micropiles inside of the cemented aggregate piers
Type Thesis
Keywords
ريزشمع خاردار، ستون شني، بهسازي خاك، نيروي بركَنش، ريزشمع
Researchers sina nazemi (Student) , Bahman Niroumand (Primary advisor) , Abdoreza Fazeli (Advisor)

Abstract

This research deals with the laboratory study of the reinforcement system of stone columns using the new method of barbed micropiles. Stone columns are a well-known method of soil improvement with a wide scope of application in all types of soils, especially weak soils. These systems are implemented by various methods and technologies based on the need. Mainly, stone columns are used in order to increase the bearing capacity and reaction modulus of the bed, reduce settlement and retrofit the soil against liquefaction. However, stone columns, except for RAP and GAP methods, they are not suitable for bearing the uplift forces on the foundation of the building caused by lateral forces like earthquakes or strong winds. During the process of tensile reinforcement of stone columns, after hammering the barbed micropile into the stone column and injecting cement slurry and connecting the concrete foundation to the upper steel plate of the micropile, it is possible to strengthen the cemented stone columns against the uplift forces. During this research, with the laboratory modeling of cemented stone columns reinforced with barbed micropiles, the effect of the number of shear barbs and shear barbs installation pattern on the pull-out capacity, tensile stiffness modulus and adhesion resistance (𝛼𝑏𝑜𝑛𝑑) of simple and barbed micropiles were studied. Based on this, 9 samples of reinforced stone column with a diameter of 30 cm and a height of 75 cm were made with different number and arrangement of shear barbs and were subjected to the micropile pull-out loading test from inside the cemented stone column. The results show that the adhesion resistance (𝛼𝑏𝑜𝑛𝑑) of barbed microcpiles is on average about 2.1 times the adhesion resistance of simple micropiles. Also, with the increase in the number of shear barbs on the micropile tube, although the pull-out load capacity of the micropile expands significantly, the tensile stiffness modulus of the micropile increases slightly.