Experimental investigation for determining the stability of the Nizhne-Kama hydroelectric station building: Fid-Bau Portal

Experimental investigation for determining the stability of the Nizhne-Kama hydroelectric station building

Evdokimov, P. D. / Aptekar', L. D. / Kashkarov, P. N. / Lipovetskaya, T. F. / Kondrat'eva, K. B.

Conclusions 1. The investigations showed that the strength characteristics of soil specimens differ substantially from the strength characteristics of the foundation as a whole. This is due both to the different mechanism of soil deformation in the shear tests, and model and block shear, and the presence in the foundation of weakened zones and fissuring, affecting the shear resistance at the base of plates and hydroelectric station buildings. Under conditions of geological structure of the Nizhne-Kama hydroelectric station building foundation, evaluation of stability in shear must be based on the results of field tests in accordance with shearing on model stamps and blocks of soil. 2. On the basis of analysis of the results of stamp and block shear tests, taking into account the engineering geologic situation, it can be recommended that the design strength characteristics of the soil in the foundation of the Nizhne-Kama hydroelectric station building be taken as tan \gp=0.5, C=0 (safety factor), instead of tan \gp=0.42 and C=0 as assumed in the design. 3. The data from investigations for clarifying the nature of soil deformation in the foundation of the hydroelectric station building point to the possibility of destruction of stability of the installation, based on the geological structure of the foundation soil or due to plane shear along the weakened contact between soil strata or the foundation reaching the limit state, accompanied by fissuring. Under conditions where two types of failure are possible, an important result of the investigations is that experimental points for both forms of limit state of the foundation are approximated by a single linear equation {ie227-1. Hence, the stability calculation for the lower Kama hydroelectric station building should be carried out in accordance with the plane shear diagram, taking into account the possibility of the shear surface occurring within the limits of weaker clay-soil differences. 4. Beyond the scope of this article, regarding the results of investigations of long-term strength of the soils in the foundation of the Nizhne-Kama building, it is observed that, since under these conditions, destruction of the strength of the soil is accompanied by fissuring processes independent of the time of application of the load, the degree of stability to shear of the Nizhne-Kama building may be determined in accordance with the above systems of calculation, using the theoretical (mean minimum) tan \gp and C values provided in the article.