The Civil Engineering Department at the College of Engineering, University of Baghdad, held Ph. D thesis examination titled:
((Reducing the earthquakes effects in the soil under the mat foundation using jet injection techniques))
By the student Sameer Hassab allah Hussien and supervised by Prof. Dr. Mahmood Thiab Ahmmed
Prof. DrBushra S. Zebar (Chairman)
Prof. Dr. Aamal A.Hussien (Member)
Prof. Dr. Mahdi O. Karkush (Member)
Prof. Dr. Hassan O. Abbas(Member)
Ass. Prof. Dr. Abbas F. Ibraheem (Member)
After conducting the public discussion and listening to the student’s defense, the thesis was accepted with an excellent degree. was summarized as follows:
The study aims to investigate the effect of Jet grouting columns (JGC) to mitigate seismic effects in sandy soil beneath raft foundations subjected to earthquake loading. Two approaches were employed in this study; experimental and numerical. The experimental part was based on forming grouted columns utilizing low-pressure injection laboratory equipment designed and manufactured locally to simulate the grouting process of field equipment and to systematically conduct unconfined compression testing (U.C.Ts.). Grouted columns with about 40 mm diameter were made by injecting the water-cement slurry in a certain weight-mixing ratio through the sandy soil, which composed of two layers lay over a gravel filter. Layer one represents a dense sand with 70% relative density lay over the filter and the second layer is a loose liquefied sand with 20% relative lay over the first one and under the raft foundation. Unconfined compression tests were employed to examine the grouted columns to find the grouted column properties after the cure period. The raft foundation was fixed on columns and erected on sandy soil for testing using a 1g horizontal direction movement shaking table under different conditions using three different earthquake intensities (Kobe 1995, El Centro 1940, and Halabja 2017) before and after improvement by JGC.
The results confirmed that jet grouting is a promising technique to reduce the seismic effect, mitigate its intensity on the soil beneath the raft foundation, and increase the superstructure’s stability during an earthquake
A numerical part was taken to verify the experimental results using PLAXIS 3D 2020. Its results are consistent with the experimental outcomes, and that gives reliability to the results obtained in experimental tests.
