A new failure mechanism for deep cavity and upper bound solution of supporting pressure

2017 ◽  
Vol 24 (9) ◽  
pp. 2082-2091 ◽  
Author(s):  
Dao-bing Zhang ◽  
Zhi-zhen Liu ◽  
Jia-hua Zhang
2008 ◽  
Vol 24 (3) ◽  
pp. 285-296 ◽  
Author(s):  
J.-C. Chang ◽  
J.-J. Liao ◽  
Y.-W. Pan

AbstractThis paper aims to investigate the failure mechanism of a shallow foundation on poorly cemented sandstone and to propose an upper bound solution for the bearing capacity of the foundation. A series of laboratory material and load-bearing model tests with specimens made of artificial rock mimic undisturbed natural poorly cemented sandstone.Based on a series of load-bearing model tests, bearing behavior and progressive failure mechanisms are investigated. It was found that the bearing behavior on poorly cemented sandstone is distinct from the cases on hard rock or on soil, and exhibits both plasticity and brittle characteristics. It is noted that the bearing capacity formulas for a shallow foundation commonly used for soil or hard rock are not appropriate for the case of poorly cemented soft sandstone. Based on the observed failure mechanism, a simplified plastic collapse mechanism is proposed and an upper-bound solution on the basis of a multi-block translation mechanism is formulated. It is shown that the upper bound solution agrees well with the experimental bearing capacity as long as a proper non-associated flow rule is adopted.


2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Cheng-yang Wang ◽  
He-lin Fu ◽  
Jun-zhe Liu

The linear failure criterion is generally adopted in the stability problem of geotechnical engineering, whereas the experiments have indicated that there is a nonlinear relationship between the maximum and minimum principal stresses in weak surrounding rock. According to the characteristics of weak rock, the failure mechanism of deep cavity is constructed by combining the nonlinear Hoek–Brown failure criterion and the upper bound theorem of limit analysis. The upper bound solution of the surrounding rock pressure was deduced using the tangent method. The results show that the surrounding rock pressure of deep cavity is affected by surrounding rock grade, cavity depth, and section size. Especially, the influence of the disturbance factor is quite obvious. Upper bound solution based on nonlinear Hoek–Brown failure criterion can fully take the influence of parameters on surrounding rock pressure. Therefore, this method is more scientific than the linear failure criterion to calculate the surrounding rock pressure.


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