Abstract:

The stability of the trench walls of extradeep diaphragm walls is analyzed on basis of the physical and mechanical properties of the soil strata, the artesian water head and the wallprotection slurry. The safety coefficient of the trench walls is analyzed and provided on basis of analytical theory and numerical calculation of the stability of the trench walls. Countermeasures for the slurry protection of the trench walls of extradeep diaphragm walls are proposed. The conclusions drawn are as follows: 1) Special attention should be paid to the adjustment of the unit weight and level of the slurry in case multiple layers of artesian water heads exist in the extradeep strata; 2) It is proposed that the unit weight of the slurry prepared during construction should reach 12.5kN/m3, the slurry level should be increased by 1m by means of guide walls and the safety coefficient should reach 1.4; 3) The construction practice shows that when the unit weight of the slurry is controlled to range from 11kN/m3 to 13 kN/m3, the stability of the trench walls can be effectively guaranteed. 

Key words: diaphragm wall, trench wall stability, slurry protection, artesian water head