›› 2010, Vol. 31 ›› Issue (11): 3373-3378.

• Fundamental Theroy and Experimental Research • Previous Articles     Next Articles

Failure mechanism and ultimate bearing capacity of strip footing above void

LIU Hui1,YANG Feng2,YANG Jun-sheng2   

  1. 1. School of Civil Engineering and Architecture, Changsha University of Science and Technology, Changsha 410076, China; 2. School of Civil and Architectural Engineering, Central South University, Changsha 410075, China
  • Received:2009-08-10 Online:2010-11-10 Published:2010-11-24

Abstract:

The most important step of solving ultimate bearing capacity problem by using upper bound limit analysis is to form a suitable failure mechanism. The failure mechanism becomes complex when there is a void beneath the footing. By analyzing the mechanic properties and failure shape of strip footing above void, its failure mechanism was formed and the failure range was divided by various rigid and transition area. Upon upper bound method, the velocity field corresponding to failure mechanism was built, and the energy caused by external force and energy dissipation under limit state was deduced. Thus the object function of ultimate bearing capacity can be obtained and solved by mathematic optimization. Finally, the influence factors of ultimate bearing capacity, such as void roof thickness and size, were analyzed by using calculating example. The obtained results were also compared with the case which no void contains. It shows that ultimate bearing capacity is increased with the increase of void roof thickness and the range of failure mechanism is therefore diffusing from area beneath the footing to both sides of footing. And there also exists a critical void roof thickness beyond which, the influence of void can be neglect..

Key words: foundation, strip footing, void, ultimate bearing capacity, upper bound method

CLC Number: 

  • TU 47
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