eva‎luation of strength of jet grout columns using in situ shear test

5/17/2023 12:00:00 AM

In the face of soil that does not have sufficient resistance to withstand the load caused by structures built on it and also loose soils, the jet grouting method is used to improve the soil. The basis of jet grotting is high pressure single, double and triple injection. The hydrodynamic action of the jet should break the initial structure of the soil and move part of the soil out with the slurry so that the rest of the soil is mixed with the grout. This action creates a mass of cement and soil in the soil, the cross section of which is often cylindrical, which is called a jet grouting column. After the execution of jet grouting columns, quality control operations are usually performed by corrugating the columns. Nucleation causes problems such as applying stress to the cores, breaking them, and their small scale, which do not represent the entire section. Therefore, in this dissertation, in situ cutting test has been performed on jet grouting columns. Due to the very high costs of supplying equipment, materials and execution, only 4 columns have been executed and examined. In the following, the purpose of the research is stated in detail. In this dissertation, the aim is to review and compare the results of in situ direct shear test and the executive parameters of jet-grouting columns, including injection pressure, drilling rod rise speed and rotation speed. On-site experiments on jet-grouting columns in the field are the criteria for operation, which is being investigated in the bed soil improvement project for the construction of a hotel in the city of Chalous. In the jet grouting project, after performing a series of test columns and after setting the columns (28 days), the excavation operation is performed at the desired levels and the cutting test is performed on site. The core is then taken from the test column under test and the uniaxial resistance test is performed on it in the laboratory of the University of Science and Technology. Finally, the strength results obtained from different experiments are compared with each other and the effect of the test method on the strength results is investigated and the behavior of cement soil columns made using jet grouting technique is compared with the behavior of concrete and soil. It should be noted that in situ cutting test equipment, which is a large-scale direct cutting test designed and built by Haji Salimi (PhD student at the University of Science and Technology) for this purpose. The diameter of the columns and the uniaxial compressive strength of the obtained cores were calculated and investigated. Using in situ shear test results, Herston strain stress diagrams, pressure diagrams in diameter, uniaxial compressive strength and shear of four columns were compared and finally compressive strength diagrams in shear strength of four columns were examined. The results are described below in the form of an input data table in this experiment and the diagrams mentioned.

آزمايش برش برجا , جت‌گروتينگ , بهسازي خاك , مقاومت برشي , مقاومت فشاري , جابجايي افقي

situ shear test , jet grouting , Soil improvement , Shear strength , Compressive strength , Shear strength , Horizontal displacement

Hesam Asef zadeh

Dr. Mohsen Sabermahani