High quality of joints between panels (to exclude any mud joints) was ensured by removable stopends ("Stopsol") of preliminary trench portions, as well as by preliminary excavation of secondary and following portions until removed.
According the general designer claim execution of longitudinal grooves of depth under 70 mm in the places of the foundation slab and intermediate floor-slabs joining and rebar outlets – in the places of floor-slabs joining.
Grooves in diaphragm walls were formed by filling the required zones of reinforcing cages with polystyrene foam blocks, covered in PE film t=0.16 mm and fixed to working reinforcement by metal wire.
The ground-works and dewatering project was sacrificed in the process of pit excavation by the developer to save money with the hope that the contractors can solve these problems themselves using the allocated funds. As a result the excavation had being executed practically without a project and often caused our dissatisfaction with soil excess and untimely temporary support installation.
Temporary support of excavation pit was executed as two-tired. The upper tire of buntons and braces made of 820 mm diameter metal pipes was supported by an in-situ reinforced concrete framing beam along of the diaphragm walls top. The lower tire of buntons and braces made of 820 - 1020 mm diameter metal pipes was supported by a belt made of the three-throw flange beams ¹55Á1.
During the soil excavation on the lower layer (to the excavation pit bottom designed level) through the fractured marl seams in the layer of Neverovsky marly-clays water began to enter the excavation pit from the Rutmirovsky horizon with water production of 5-6 m3
/h from the area of 600-700 m2
, which required preventive measures against pressure water inrush and flooding of the pit.
As a result the customer had to break the excavation and promptly order a project of dewatering of Rutmirovsky horizon pressure waters to professionals. Dewatering and observation boreholes were placed partly outside the contour and partly – inside the excavation pit. Total of boreholes production was about 300 m3