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Overall summary of Administrative-commercial project of Azadi-Ostad Moein:
Administrative-commercial project of Azadi-Ostad Moein was one of the earth retention projects of Istasazeh corporation which was located in Azadi str near the Ostad Moein subway station. The area of the project site was around 1684 square meters and the area occupied by the structure at its lowest storey was about 1585 square meters. Istasazeh corporation was not only responsible for designing the stabilizing system of excavation walls and the drainage system but, also responsible for designing the structural skeleton and structural systems which included vertical bearings and lateral bearings. Based on the structural and architectural designs and the plans presented by the client, the structure appeared to be a 16-floor building including 1 ground floor, 7 underground floors and 8 floors above the ground. With regard to the design and the thickness of the foundation, the maximum depth of the excavation should’ve been 26 meters. It is important to note that according to the context of the contract, the excavation and construction project had to be operated from top to down. After the designing team had visited the site and the reports on soil mechanics and foundation engineering had been presented by the client, the process of designing a stabilizing system got on the schedule. One of the unique decisions made during the process was over securing some parts of the excavation wall in order to comply with urban construction legal requirements even though the client had not asked for it.
Challenges of Administrative-commercial project of Azadi-Ostad Moein:
Taking the neighbor buildings and their overloads into consideration is very important in stabilizing and excavation projects when it comes to design and construction. Surroundings of this project were a mixture of streets and residential buildings. Azadi str was adjacent to the northern side and Shahid Shojaei alley was adjacent to the southern side of the excavation wall. From the other hand, an old 6-storey building (with one basement) and its yard was adjacent to the eastern side and another old 3-storey building (with one basement) was adjacent to the western side of the excavation. The presence of these residential buildings and the lack of cooperation from its residents, led to a difficulty towards acquiring the legal consents required from the neighbors for the excavation project. This was due to the existence of a legal requirement that demands the consent of adjacent neighbors regarding any construction that would affect their buildings such as soil nailing and soil anchoring the sub-foundation. Any hypothetical complaint from these residents can legally suspend the project. The long efforts of the client regarding the consent of the neighbors were unsuccessful and thus, constructions such as nailing and anchorage were basically impossible for the western and eastern walls of the excavation.
Solutions in Administrative-commercial project of Azadi-Ostad Moein:
It is worth to say that in Azadi-Ostad Moein project, Istasazeh corporation presented different methods for the top-down excavation and for stabilizing the northern and southern walls to give the client a variety of choices. The client then decided to choose a top-down excavation method to comply with the overall purpose of the project.
For the stabilizing methods such as soil nailing, soil anchorage, strutting, and truss retaining structures, the excavation process continues all the way down to the level of the foundation and then the foundation and the structural floors will be constructed. After reaching the level of each floor, the parts of the retaining structure that interfere with the main structure would be eliminated. The basement floors are constructed one by one until the structure reaches the ground level. At this point the construction of the underground structure is finished. In this method the underground structure is constructed from down to top which is the most common way of constructing these structures. As a matter of fact, inclined excavation, strutting, truss retaining structure, nailing, and anchorage are all constructed from down to top.
Top-down excavation and construction method, however, is the opposite of down to top constructions. In this method the construction of underground structures starts from top to down as a result it is called a top-down method. In this method, after each step of the excavation, the roof of each floor will be constructed using molds and concrete pouring. In this method, the roofs are an integral part of the main structure and thus are permanent. In the top-down method, the roofs bear the lateral pressure from the walls of the excavation, just like the bearing beams in the Struts method. As a result, the construction of the sub-ground structure finishes when the excavation reaches its lowest point.
The roofs that are built by this method are heavier than the beams used in Struts method. Also, the pavement construction can be done simultaneously to the underground structure. These all together adds to the load being forced on the columns, so this load should be taken into consideration. Concrete of steel piles are the best choice for foundation in the top-down method.
Administrative-commercial project of Azadi-Ostad Moein
Overall summary of Administrative-commercial project of Azadi-Ostad Moein:
Administrative-commercial project of Azadi-Ostad Moein was one of the earth retention projects of Istasazeh corporation which was located in Azadi str near the Ostad Moein subway station. The area of the project site was around 1684 square meters and the area occupied by the structure at its lowest storey was about 1585 square meters. Istasazeh corporation was not only responsible for designing the stabilizing system of excavation walls and the drainage system but, also responsible for designing the structural skeleton and structural systems which included vertical bearings and lateral bearings. Based on the structural and architectural designs and the plans presented by the client, the structure appeared to be a 16-floor building including 1 ground floor, 7 underground floors and 8 floors above the ground. With regard to the design and the thickness of the foundation, the maximum depth of the excavation should’ve been 26 meters. It is important to note that according to the context of the contract, the excavation and construction project had to be operated from top to down. After the designing team had visited the site and the reports on soil mechanics and foundation engineering had been presented by the client, the process of designing a stabilizing system got on the schedule. One of the unique decisions made during the process was over securing some parts of the excavation wall in order to comply with urban construction legal requirements even though the client had not asked for it.
Challenges of Administrative-commercial project of Azadi-Ostad Moein:
Taking the neighbor buildings and their overloads into consideration is very important in stabilizing and excavation projects when it comes to design and construction. Surroundings of this project were a mixture of streets and residential buildings. Azadi str was adjacent to the northern side and Shahid Shojaei alley was adjacent to the southern side of the excavation wall. From the other hand, an old 6-storey building (with one basement) and its yard was adjacent to the eastern side and another old 3-storey building (with one basement) was adjacent to the western side of the excavation. The presence of these residential buildings and the lack of cooperation from its residents, led to a difficulty towards acquiring the legal consents required from the neighbors for the excavation project. This was due to the existence of a legal requirement that demands the consent of adjacent neighbors regarding any construction that would affect their buildings such as soil nailing and soil anchoring the sub-foundation. Any hypothetical complaint from these residents can legally suspend the project. The long efforts of the client regarding the consent of the neighbors were unsuccessful and thus, constructions such as nailing and anchorage were basically impossible for the western and eastern walls of the excavation.
Solutions in Administrative-commercial project of Azadi-Ostad Moein:
It is worth to say that in Azadi-Ostad Moein project, Istasazeh corporation presented different methods for the top-down excavation and for stabilizing the northern and southern walls to give the client a variety of choices. The client then decided to choose a top-down excavation method to comply with the overall purpose of the project.
For the stabilizing methods such as soil nailing, soil anchorage, strutting, and truss retaining structures, the excavation process continues all the way down to the level of the foundation and then the foundation and the structural floors will be constructed. After reaching the level of each floor, the parts of the retaining structure that interfere with the main structure would be eliminated. The basement floors are constructed one by one until the structure reaches the ground level. At this point the construction of the underground structure is finished. In this method the underground structure is constructed from down to top which is the most common way of constructing these structures. As a matter of fact, inclined excavation, strutting, truss retaining structure, nailing, and anchorage are all constructed from down to top.
Top-down excavation and construction method, however, is the opposite of down to top constructions. In this method the construction of underground structures starts from top to down as a result it is called a top-down method. In this method, after each step of the excavation, the roof of each floor will be constructed using molds and concrete pouring. In this method, the roofs are an integral part of the main structure and thus are permanent. In the top-down method, the roofs bear the lateral pressure from the walls of the excavation, just like the bearing beams in the Struts method. As a result, the construction of the sub-ground structure finishes when the excavation reaches its lowest point.
The roofs that are built by this method are heavier than the beams used in Struts method. Also, the pavement construction can be done simultaneously to the underground structure. These all together adds to the load being forced on the columns, so this load should be taken into consideration. Concrete of steel piles are the best choice for foundation in the top-down method.
