Volume 24, Issue 2 (2024)
MCEJ 2024, 24(2): 139-156 |
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Mansoori M, labib A, Akhtarpour A. the effect of matric suction changes on the behavior of Anchored excavations in expansive soil. MCEJ 2024; 24 (2) :139-156
URL: http://mcej.modares.ac.ir/article-16-68351-en.html
URL: http://mcej.modares.ac.ir/article-16-68351-en.html
1- Ferdowsi University of Mashhad, Faculty of Engineering, Department of Civil Engineering
2- Ferdowsi University of Mashhad, Faculty of Engineering, Civil Engineering Department ,akhtarpour@um.ac.ir
2- Ferdowsi University of Mashhad, Faculty of Engineering, Civil Engineering Department ,
Abstract: (1510 Views)
Due to the increase in population and the increasing need for construction, the issues related to excavation and stability of the excavation have been given importance. The stability of excavations can be controlled and improved by various methods such as anchoring, retaining walls, shielding, etc. that in each project, according to the characteristics of that project and the type of factors threatening the stability of that excavation, one or more stabilization methods can be used. The excavation investigated in this research is stabilized by two pile-anchor and concrete pile methods. One of the factors leading to the instability of the excavation is the infiltration of water into the excavation. Water infiltration into the excavation can be due to various reasons such as rainfall, rise of the underground water level, pipe burst, etc.; Therefore, the possibility of water infiltration into the excavation should be checked in each excavation, and necessary measures should be taken in case of water infiltration. matric suction is defined as the difference between pore air pressure and pore water pressure, which plays a major role in the shear resistance behavior of unsaturated soils; Now, water infiltration reduces matric suction and as a result reduces shear resistance and increases soil volume in expansive soils. The excavation studied in this research has been exposed to factors that change matric suction such as pipe burst, absorption well and climate conditions. The boundary conditions of pipe bursting and absorption well are assumed for a period of one year; Also, the weather conditions have been obtained from the meteorological data of the two rainy months of Sarakhs city. Using sigma/W software and Couple analysis, the simultaneous effect of change in matric suction and change in stress and strain has been investigated. Also, the Penman-Monteith method has been used for the calculation of evaporation and transpiration to model the climate conditions. In this research, a comparison was made between different excavation stabilization situations (pile-anchor and pile method) under different conditions of matric suction (pipe burst, absorption well and weather conditions). Also, in this research, the effect of the location of the burst pipe and absorption well (distance from the excavation wall) on factors such as deformations, the moment created in the pile and the forces created in the anchors (behavior of the excavation) was investigated. Considering the destructive behavior of expansive soils in unsaturated conditions, the soil studied in this research is of expansive type. The characteristics of the modeled soil are related to the area of Sarakhs city. In order to consider the effect of soil swelling, the used elasticity modulus is related to the effective stress and as a result matric suction, which is called the swelling modulus. The results showed that the increase in moisture in the soil and as a result the decrease in matric suction in the swelling soil increases the force in the anchors and the bending moment in the pile. Also, the increase in the force of the anchors and the displacement created in the case of pipe bursting and absorption well modeling is much more than the conditions of the climate boundary effect for the two rainy months of the year. By increasing the distance of the absorption well and the bursting of the pipe from the excavation, the increase in the force created in the anchors decreases. climate conditions affect the upper 6 meters of the excavation, i.e. the active zone.
Keywords: unsaturated soil, expansive soil, excavation stabilization, Couple analysis, absorption well, pipe burst, climate condition
Article Type: Original Research |
Subject:
Geotechnic
Received: 2023/04/5 | Accepted: 2023/10/19 | Published: 2024/02/29
Received: 2023/04/5 | Accepted: 2023/10/19 | Published: 2024/02/29
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