Calculation Method of Underground Cavern Loosening Pressure Based on Limit Analysis Using Upper-Bound Theory and Its Engineering Application

From the point of view of the failure mechanism of the disturbed zone, this paper uses the limit analysis upper-bound theory to analyze the calculation formula of the loosening pressure, distinguish the difference between the vertical pressure and the horizontal pressure in the underground cavern, combine the loosening characteristics of the disturbed zone with the open-type disturbed zone and the annular disturbed zone, and construct the multirigidity slider translation and rotation failure mode to discuss the calculation method of surrounding rock loosening pressure of underground caverns in upper soft and hard rock stratum. The relevant calculation examples are given, and the application of the upper-bound theory of limit analysis is demonstrated in detail. Based on the actual engineering background, the calculation results of the calculation method of the loosening pressure of the cavity based on the upper-bound theory of the limit analysis are analyzed and compared for the different depths and different types of caverns. The difference, rationality, and applicability of the calculation results of this method are analyzed and discussed.

Effects of helicity on dissipation in homogeneous box turbulence

The dimensionless dissipation coefficient$\unicode[STIX]{x1D6FD}=\unicode[STIX]{x1D700}L/U^{3}$, where$\unicode[STIX]{x1D700}$is the dissipation rate,$U$the root-mean-square velocity and$L$the integral length scale, is an important characteristic of statistically stationary homogeneous turbulence. In studies of$\unicode[STIX]{x1D6FD}$, the external force is typically isotropic and large scale, and its helicity$H_{f}$either zero or not measured. Here, we study the dependence of$\unicode[STIX]{x1D6FD}$on$H_{f}$and find that it decreases$\unicode[STIX]{x1D6FD}$by up to 10 % for both isotropic forces and shear flows. The numerical finding is supported by static and dynamical upper bound theory. Both show a relative reduction similar to the numerical results. That is, the qualitative and quantitative dependence of$\unicode[STIX]{x1D6FD}$on the helicity of the force is well captured by upper bound theory. Consequences for the value of the Kolmogorov constant and theoretical aspects of turbulence control and modelling are discussed in connection with the properties of the external force. In particular, the eddy viscosity in large-eddy simulations of homogeneous turbulence should be decreased by at least 10 % in the case of strongly helical forcing.

Investigation of Bearing Strength of Single-Bolt Double-Lap Joints in Composite Laminate

Based on the Upper Bound Theory, a Simplified Engineering Approach is Presented to Determine the Ultimate Strength of a pin-Loaded Composite Laminate in this Papaer. According to the Upper Bound Theory, the Displacement Rate in a Given Ply is Divided into Two Zones: the Moving Zone and the Static Zone. the Applied Load Q that Associated with Displacement must be Less than the Maximum Resistance of the Laminate. in this Paper we have Discussed the Failure Region, Failure Type of each Ply and Simplified the Tsai-Wu Failure Criterion. Experiments of Single-Bolt Double-Lap Joints have been Conduncted According to ASTM D5961 Test Standard. Finally, we can Observe that the Engineering Approach is in Good Agreement with the Test Results.

Study on the Critical Height of Homogeneous Clay Slope

Small cohesion clay slope is possible to slide along the plane slip surface or log-spiral slip surface. Based on the upper bound theory and energy principle, this paper deduced the critical height of the inclined top clay slope. The sliding mode of plane slip surface and log-spiral slip surface is studied. Finally, an engineering example is analyzed and the critical height calculation is introduced.