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Critical State Soil Mechanics Phần 9

Tham khảo tài liệu 'critical state soil mechanics phần 9', khoa học tự nhiên, công nghệ môi trường phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 174 c Fig. 9.11 Local Failure of River Bank For example imagine in Fig. 9.12 a wide river passing across land where there is a considerable depth of clay with cohesion k 3 tonnes m2 and of saturated weight 16 tonnes m3. If the difference of level between the river banks and the river bed was h then ignoring the strength of the clay for the portion BD of the sliding surface Fig. 9.12 Deep-seated Failure of River Bank 9.12 so that and the weight of the wedge BDE for an approximate calculation we have q 1.6h and p Ywh 1.0h when the river bed was flooded or p 0 when the river bed was dry giving in the worst case q - p 1.6h. We also have from eq. 9.11 q - p 5.53k 16.6 tonnes m2 h 10m say 1.6 which gives one estimate of the greatest expected height of the river banks. If the river were permanently flooded the depth of the river channel could on this basis be as great as 166 27.6m. 9.13 0.6 An extensive literature has been written on the analysis of slip-circles where the soil is assumed to generate only cohesive resistance to displacement. We shall not attempt to reproduce the work here but instead turn to the theory of plasticity which has provided an alternative approach to the solution of the bearing capacity of purely cohesive soils. 9.5 Discontinuity Conditions in a Limiting-stress Field In this and the next section we have two purposes the principal one is to develop an analysis for the bearing capacity problem but we also wish to introduce Sokolovski s notation and provide access to the extensive range of solutions that are to be found in his Statics of Granular Media. In this section we concentrate on notation and develop simple conditions that govern discontinuities between bodies of soil each at some Mohr 175 Rankine limiting stress state in the next section we will consider distribution of stress in a region near the edge of a load a so-called field of stresses that are everywhere limiting stresses. Fig. 9.13 Two Rectangular Blocks in Equilibrium with .