Wide-area excavations, part 2

tmpe4c2-1Drilled anchors (injection); 1 - I-section, 2 — bale, 3 - cable, 4 - mace.

The figure shows a supporting wall with ground anchors. The ground anchors are introduced into the ground by drilling or hammering as the trench is deepened. The end part of the hole is filled under pressure with cement mortar, which creates the so-called. mace. The tendon is made of a rod protected against corrosion. These types of anchors can be used both for temporary walls, as well as fixed and of almost any height. Excavations in the vicinity of existing buildings can also be secured in cohesive soils with walls made of reinforced concrete piles.

To avoid the impact of harmful vibrations on existing buildings, these piles in cohesive soils are usually drilled of the Wolfsholz type. Vibrations caused by the driving of piles can crack and scratch buildings. A wall made of piles carries both the loads of the building, as well as ground pressure.

Particular attention should be paid to this when securing excavations in the vicinity of existing buildings, so that these protections are not deformed, which would cause the ground to slide out from under existing buildings, as this could damage them. In the case of the excavation above 3,0 m piles should be additionally supported with braces, and do the robots in stages.

In the case of waterlogged land, when the groundwater level is high and it may flood the trench during the works, then the excavations are made after the sheet piling is driven in, the so-called. palisady, and the works in the trench are carried out with a low water level, which is obtained by constant pumping.

tmp4cad-1Reinforced concrete pile wall securing the excavation and the existing building: a) vertical section, b) horizontal cross section; 1 - reinforced concrete pile, 2 - brace.