The axes of activity and provision of services of Istasazeh Engineering Construction Co. in the field of earthworks of projects generally include the demolition and excavation.
Istasazeh Construction Co. earthworks services include demolition and excavation:
- Demolition
- Excavation
- Application of earth-moving in buildings excavation
- Ramp and collect ramps in excavation and earth-moving
1) Demolition
Given that demolition is the first phase of construction and produces construction debris, it can have many effects on the environment. In addition, the demolition of the building can cause human and financial damage, as well as endanger the health of the project staff and damage the surrounding environment.
The issue of demolition in Tehran has not been specifically considered and no regulations have been prepared for it. Of course, there are scattered rules for demolition in publications and regulations:
- Chapter Twelve of National Building Regulations
- Publication of construction specifications of the construction works of management organization
- Regulations for the protection of construction workshops of the Ministry of Labor and Social Affairs
2) Excavation
All activities related to the demolition, and earth-moving of any type of land, accumulation, relocation, loading and transportation of any earth material within the project or outside it (if necessary) that is related to the activities subject to the contract are called excavation. This operation is mainly done with light or heavy road construction machinery and equipment, although manual or explosive methods may be used if necessary and depending on the situation.
One of the activities related to earth moving and excavation is leveling and regulating the wall. To all activities related to leveling, preparation, smoothing, removal of debris, filling cavities, etc., at all levels of earth moving, in order to create a suitable substrate for drainage layer or installation of steel mesh, in order to perform activities related to the subject of the contract is called regulating. This operation is mainly done using manpower and light equipment, although machinery and materials or other methods may be used if needed.
The regulating operation is performed in order to create a smooth substrate for the installation and execution of drainage (if any) and steel mesh and is mainly done using manpower and light tools and equipment.
For this purpose, surface protrusions, such as rubble or bumps left after earth moving, should be removed if the height of the protrusion exceeds the thickness of the shotcrete. Otherwise, the distance of the steel mesh from the wall surface and the thickness of the shotcrete from the bumps are calculated.
A large protrusion, such as boulder parts, should be properly removed if the bulk of the volume is off the surface. The method of removing this protrusion should be such that it does not damage the adjacent points. If most of the large rock fragments are located in the soil, its preservation is allowed provided that it does not pose a problem of general or local stability, otherwise the protruding part must be properly destroyed. Local indentations that are filled with shotcrete during the application of the surface coating and do not interfere with the installation of the mesh, No need for regulation and repairing. Significant indentations (in terms of depth or extent) that make it difficult to install the mesh or cause technical or operational problems for any of the activities of the retaining structure, should be filled appropriately.
The above-mentioned cases are mainly related to earthworks within approximately 10 m of the project line. Earthworks inside the excavation, at a distance of at least 10 m from the project line, with approved methods and under the supervision of the supervisory body, almost uniformly (maximum level difference of 10 m and maximum overall slope of 10%) will be made at the bottom of the excavation and in accordance with progress in the execution of the retaining structure.
Application of earth moving in excavation of buildings
Earth moving starts in sections (panelized) from the top of the trench and continues during the earth moving phases, with a certain height and length. Earth moving operations inside the excavation at a distance of at least 0.5 m from the project line, is possible using machines such as loaders (which have less execution accuracy), but the area of 0.5 m from the project line should be using machines with greater accuracy, such as an excavator. The first phase of earth moving has a height at which the soil can remain unprotected for a short time (about 24 to a maximum of 48 hours) and a maximum of 2 m (equivalent to the width of the steel mesh sheet).
The height of the next phases of earth moving will be at most equal to the width of a steel mesh or less, according to the supervisory body (based on the conditions of wall stability). Earth moving without the execution of a retaining structure (or at least the application of a surface cover, at levels where there is no nail in the moved panel according to the surveys) with a height greater than the width of a steel mesh is not normally allowed, unless confirmed by calculations. Otherwise, the contractor must announce his amendment proposal to the supervisory body and finally, according to the supervisory body, take corrective action as soon as possible.
The length of each earth moving section (panel) varies depending on the condition of the excavation wall. In general, the length of earth moving panels is 6 m. In loamy soils, or loose and low strength, or in cases where the stability and displacement of the excavation wall in case of long panel removal are questionable, the maximum length of each panel can be reduced up to the equivalent of a horizontal distance of two adjacent nails. In grounds with sufficient strength, the maximum allowable panel length is a function of the contractor’s executive power. The most critical state of instability is usually seen at runtime. Instability is most likely to occur after drilling and before performing shotcrete and soil nailing. For this purpose, after each drilling phase, the appearance of the slope should be considered. The blow up and the appearance of excessive displacement are some of the cases that can be a prelude to the occurrence of instability and shedding. If signs of instability occur, they should be reported immediately.
Ramp and collecting it in excavation and earth-moving
Excavation often require the construction of ramps. One of the problems of Excavation is collecting ramps. For this purpose, according to the depth of the excavation, there are different methods for collecting ramps, which are described in the article Ramp and collecting ramps in an excavation.
