Use of a non-associated flow rule for determining the stability of a vertical circular excavation

2018 ◽  
Vol 14 (1) ◽  
pp. 247-252 ◽  
Author(s):  
Debarghya Chakraborty
Keyword(s):  
Flow Rule ◽  
Circular Excavation ◽  
The Stability ◽  
Associated Flow Rule

scholarly journals Analytical and Reliability Study of the Tunnel with Rockbolts in Rock Masses

2018 ◽  
Author(s):  
Qiang Meng ◽  
Hongbo Zhao ◽  
Changxing Zhu ◽  
Zhongliang Ru
Keyword(s):  
Rock Mass ◽  
Analytical Solution ◽  
Hydrostatic Stress ◽  
Yield Criterion ◽  
Plastic Zone Size ◽  
Homogenization Method ◽  
Flow Rule ◽  
Circular Tunnel ◽  
The Stability ◽  
Associated Flow Rule

Rockbolts are a critical reinforcement ways which widely used in tunnel engineering. In this paper, an analytical solution of circular tunnel with rockbolts was proposed based on homogenization method, and then the stability of a circular tunnel was investigated by considering the uncertainty based on the proposed analytical solution. Elastoplastic analytical solution for unsupported circular tunnel was presented briefly in hydrostatic stress field with a linear Mohr-Coulomb yield criterion and a non-associated flow rule. An analytical solution of circular tunnel with rockbolts was proposed through considering rock mass and rockbolts as a new homogeneous, isotropic, parameters strengthened equivalent composite material. A numerical example is used to verify the proposed analytical solution. The results show that the proposed solution can effectively characterize the mechanical behavior of rock mass and rockbolts in tunnel. Then, the proposed solution is adopted to calculate reliability index and failure probability of tunnel. The results show that the proposed method can also be effectively used to perform the stability and reliability analysis of tunnel and rockbolts have an important effect on plastic zone size and displacement of tunnel.

scholarly journals Stability Charts for Sustainable Infrastructure: Collapse Loads of Footings on Sandy Soil with Voids

2019 ◽  
Vol 11 (14) ◽  
pp. 3966 ◽  
Author(s):  
Joon Kyu Lee ◽  
Jaehong Kim
Keyword(s):  
Sustainable Development ◽  
Numerical Solutions ◽  
Friction Angle ◽  
Flow Rule ◽  
Sustainable Infrastructure ◽  
Design Charts ◽  
Void Shape ◽  
The Stability ◽  
Associated Flow Rule ◽  
Bearing Capacity Factor

The presence of underground voids in regions suitable for sustainable development can adversely affect the stability of the overlying infrastructures. In this paper, the collapse loads of strip rigid footings resting on sand with single and double continuous voids are determined for a frictional Mohr-Coulomb material following the non-associated flow rule. For use by practitioners, design charts are proposed to evaluate the well-known bearing capacity factor Nγ as a function of the dimensionless parameters related to the vertical and horizontal void distances from the footing, void shape, and spacing between the two voids, as well as the soil friction angle. The computational result compares quite favorably with the available theoretical and numerical solutions. The failure mechanism is broadly discussed based on the pattern of soil displacement around the footing and void.

Gradient of Soil Constitutive Model

2010 ◽  
Vol 168-170 ◽  
pp. 1126-1129
Author(s):  
Wen Xu Ma ◽  
Ying Guang Fang
Keyword(s):  
Plastic Strain ◽  
Strain Gradient ◽  
Soil Analysis ◽  
Natural Material ◽  
Flow Rule ◽  
The Finite Element Method ◽  
Gradient Effect ◽  
Non Local ◽  
Associated Flow Rule ◽  
Plastic Strain Gradient

For the soil is a very complex natural material, significant strain gradient effect exist in soil analysis. Based on the "gradient" phenomenon, we add the plastic strain gradient hardening item into the traditional Cambridge yield surface. By using the consistency conditions and associated flow rule, we get the explicit expression of plastic strain gradient stiffness matrix. And the finite element method of plastic strain gradient is also shown in this article. Plastic strain gradient is actually a phenomenological non-local model containing microstructure information of the material. It may overcome the difficulties in simulating the gradient phenomenon by traditional mechanical model.

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