Based on nonlinear failure criterion,a three-dimensional failure mechanism of the possible collapse of deep tunnel is presented with limit analysis theory.Support pressure is taken into consideration in the virtual wo...Based on nonlinear failure criterion,a three-dimensional failure mechanism of the possible collapse of deep tunnel is presented with limit analysis theory.Support pressure is taken into consideration in the virtual work equation performed under the upper bound theorem.It is necessary to point out that the properties of surrounding rock mass plays a vital role in the shape of collapsing rock mass.The first order reliability method and Monte Carlo simulation method are then employed to analyze the stability of presented mechanism.Different rock parameters are considered random variables to value the corresponding reliability index with an increasing applied support pressure.The reliability indexes calculated by two methods are in good agreement.Sensitivity analysis was performed and the influence of coefficient variation of rock parameters was discussed.It is shown that the tensile strength plays a much more important role in reliability index than dimensionless parameter,and that small changes occurring in the coefficient of variation would make great influence of reliability index.Thus,significant attention should be paid to the properties of surrounding rock mass and the applied support pressure to maintain the stability of tunnel can be determined for a given reliability index.展开更多
Based on the design principles of economic rationality and safety,multiple-pivot pile anchorage approach was used as the supporting engineering of a tall building with a deep foundation ditch.The designs,such as ancho...Based on the design principles of economic rationality and safety,multiple-pivot pile anchorage approach was used as the supporting engineering of a tall building with a deep foundation ditch.The designs,such as anchor arm,single pile and the whole,were set up in accordance with the calculations of the internal force from the equivalent beam and Yamagata Kunio methods.Moreover,the rationality of the design was estimated using the stability checks.FLAC3D was used for calculating the accuracy of the design.Using FLAC3D to simulating ditch cutting and supporting processes can obtain the equivalent results as the theory analysis in the displacement of ditch surrounding wall,the stress field and stress distribution.展开更多
基金Project (2013CB036004) supported by National Basic Research Program of China
文摘Based on nonlinear failure criterion,a three-dimensional failure mechanism of the possible collapse of deep tunnel is presented with limit analysis theory.Support pressure is taken into consideration in the virtual work equation performed under the upper bound theorem.It is necessary to point out that the properties of surrounding rock mass plays a vital role in the shape of collapsing rock mass.The first order reliability method and Monte Carlo simulation method are then employed to analyze the stability of presented mechanism.Different rock parameters are considered random variables to value the corresponding reliability index with an increasing applied support pressure.The reliability indexes calculated by two methods are in good agreement.Sensitivity analysis was performed and the influence of coefficient variation of rock parameters was discussed.It is shown that the tensile strength plays a much more important role in reliability index than dimensionless parameter,and that small changes occurring in the coefficient of variation would make great influence of reliability index.Thus,significant attention should be paid to the properties of surrounding rock mass and the applied support pressure to maintain the stability of tunnel can be determined for a given reliability index.
基金Supported by Project of the National High Technology Research and Development Program of China(No.2003AA602250)
文摘Based on the design principles of economic rationality and safety,multiple-pivot pile anchorage approach was used as the supporting engineering of a tall building with a deep foundation ditch.The designs,such as anchor arm,single pile and the whole,were set up in accordance with the calculations of the internal force from the equivalent beam and Yamagata Kunio methods.Moreover,the rationality of the design was estimated using the stability checks.FLAC3D was used for calculating the accuracy of the design.Using FLAC3D to simulating ditch cutting and supporting processes can obtain the equivalent results as the theory analysis in the displacement of ditch surrounding wall,the stress field and stress distribution.
