Stabilization of deep pit – soil anchoring or soil containment – What is soil anchoring or soil containment? (Soil Anchorage)
rose roofing:Reserve Fing: Another method of stabilizing pits and slopes is the method of anchoring or soil containment using a strand, the method of anchoring and nailing are almost similar. After the stabilization of the pit by the method of anchoring and placement of strands, the strength of the soil increases and the increase of the strength of the soil makes it easier to complete the implementation of anchoring.
The soil anchoring method is used to stabilize pits, trenches, gables, etc., just like the nailing method. In this method, after drilling the borehole and placing the anchor, the end part of the borehole is injected, and after the cement slurry is set, the anchors are stretched and pre-tensioned with a jack.
Applying the pre-tensioning force ensures the correct functioning of the restraints. Soil Anchorage operation is often performed as Top Down Construction on a steep or vertical surface.
Anchoring or restraining is an economic and relatively new method for stabilizing slopes, gables, trenches adjacent to roads and widening roads, digging in the vicinity of structures, strengthening old guard structures, increasing load capacity, limiting deformations by creating Minimum handling and…
The length of the borehole, the length of the restraining part (the injected part or the length of the band) and the length of the free part of the restraint (the non-injected part or the band) depend on the characteristics of the soil, the depth of excavation, the tonnage of the restraining tension, the overhead of the pit, the presence or absence of underground water. and have.
A number of anchorage projects implemented by Istasazeh Company
Applications of anchoring method
The anchoring method has various uses, some of which are mentioned below:
Retaining wall next to highways
Stabilization of slopes
Preventing Uplift Pressure
Consolidation of the bed of concrete dams
Some of the applications of the anchoring method provided in the FHWA regulations – Static Engineering Construction Company
Steps of excavation by anchoring method
1. Excavation
2. drilling
3. Placing the strand or consumable reinforcement in excavation by anchoring method
4. Slurry injection in excavation by anchoring method
5. Stretching of strands in anchorage excavation
The differences between nailing and anchoring (nailing and anchoring)
Today, from an economic point of view, we will see a lot of difference in the cost of anchoring and nailing, and we conclude that nailing is less expensive than the anchoring method.
In the nailing guard structure, the need for materials and equipment is less than in the anchorage guard structure.
Stabilization of pits stabilized by the method of the nailing guard structure is done at a higher speed than the method of the anchorage guard structure.
The difference between nailing and anchoring is that in the method of implementing the anchoring guard structure, the rebars are later subjected to the post-tensioning process, and finally this factor makes this method have more power in restraining the thrust force and the fall of the ground.
The main difference between nailing and bracing is the pre-tensioning of the reinforcing member in the bracing method.
The nailing method works passively and the restraining method works actively.
In the nailing operation, the activation of the force in the nails requires deformation in the soil mass of the pit wall, but in the restraining method, due to the pre-tensioning of the restraints, before the movement of the soil mass, the force in the restraints causes a significant reduction in the deformations.
The differences between nailing and anchoring (nailing and anchoring)
Different components of restraint method
Strand or steel bar (Mono bar): The cable strand consists of 3 to 6 strong steel strands (about 1860 megapascals). According to the conditions of the project, steel rebar with lower resistance (about 400 MPa) can be used instead of the strand. A rebar that is stretched like a strand is called a monobar.
Spacer: It is used to maintain the proper distance between strands.
Centralizer: It is used to position the strand in the middle of the borehole.
Grout tube: One or more hoses are used to inject grout into boreholes.
Packer: Sometimes a packer is used for injection under pressure. The packer must withstand injection pressures and be properly sealed so that leakage does not occur from the beginning and end of the arrester.
Strand sheath (Sheath): For the following two reasons, the strands are placed inside the sheath in their free length:
Prevent strands from sticking to the grout during free length
Failure to transmit restraining force to the soil during the free length
Wedge Plate: In order to transfer the tensile force of the harness, a cylinder with several anchor head holes is installed.
Wedge: In order to lock the strand, hollow cone-shaped steel pieces are used inside the holes of the anchor head.
Anchor head plate (Bearing Plate): It is used to evenly distribute the prestressing force of the strand over a larger surface and thus reduce the stress on the wall. In this way, the hole in the wall (punch cut) is prevented.
*** If rebar is used instead of strand, some of the above components are not needed.
Different components of the restraining method with strand and rebar
Basics of designing anchoring method
The purpose of stabilizing the pit by the containment method, like the nailing method, is to create a stable mass of soil in the face of external instability. Unlike the nailing method, the restraining method works in an active manner and the prestressing force in the restraints (anchors) limits the deformation of the wall before the deformation of the soil mass begins.
