Analysis on membrane wrinkling using stress extremum method

A stress extremum method is developed based on Von Karman equations for analysis of membrane wrinkles in this paper.A mechanical model is also established for analyzing shear membrane wrinkles.Expressi...     

Numerical analysis and experimental studies of membrane wrinkles

Wrinkling patterns and the rules of wrinkling formation and expansion were analyzed in this paper. Direct disturbing method,a numerical method for membrane wrinkling analysis,was established based on finite element programme. The experimental results using photogrammetric procedure were compared with numerical analysis results. It is shown that the reasonable wrinkling deformation can be obtained by rational mesh density and timely removes the initial flaw during analysis. Wrinkles firstly appear on the left and right sides then extend to the membrane center,and the wrinkling amplitude increases with shear displacement. Results from both of the experiments and numerical analysis have a good agreement,which verifies the rationality of the numerical analysis method.     

Model test study on surrounding rock deformation and failure mechanisms of deep roadways with thick top coal

The deep roadway with thick top coal is a typical roadway difficult to support in deep mining project, and resolving this sophisticated problem to control the stability of surrounding rock is of great significance in safety production of coal mines. In order to explore the surrounding rock deformation and failure mechanisms of such deep roadways, with Zhaolou coal mine in Juye mining area of China as the engineering background, a large-scale geomechanical model test was carried out. The displacement and stress evolution laws of surrounding rock supported by the pressure relief anchor box beam system were researched. Meanwhile, the related results validate and analyze main failure characteristics and mechanisms of the surrounding rock by comparing with field test.     

Experimental studies on the mechanical properties and deformation & failure mechanism of U-type confined concrete arch centering

To solve the support problems of high stress roadways in deep mines, we developed a new 3D U-type confined concrete support system from the conventional U-type steel arch centering. Its core is the U-type confined concrete (UCC) arch centering. With a real scale mechanical test system for the confined concrete arch centering in underground engineering and numerical calculation methods, we studied in depth on the mechanical properties and deformation & failure mechanism of UCC arch centering (UCCAC). The results of the study show the yielding load and the limit load of UCC29 arch centering is 1230 kN and 1310 kN respectively in even pressure loading conditions; and a slight difference between the laboratory test and the numerical simulation on these two is 8.86% and 12.5% respectively. The deformation form of the arch centering is “vault uplifting, legs introverting and the overall shape becomes oval”; and the largest deformation occurs between the middle of the legs and the arch centering springing. The deformation and failure mechanism of arch centering is the partial strength failure causes the entire arch centering to lose its stability. The application on site shows the UCCAC has a superb effect on the surrounding rock control; therefore, the UCCAC is a new effective support for the high stress roadways in deep mines.     

薄膜二次屈曲行为的数值仿真分析

建立了薄膜二次屈曲分析的数值方法.采用施加面外扰动力的方式在薄膜中引入任意的初始缺陷,分析了薄膜的二次屈曲现象.分析表明,在薄膜的后屈曲过程中,由于初始缺陷的存在,褶皱构形不稳定,出现二次屈曲现象,产生了新的褶皱.后屈曲平衡路径呈现多阶段的特点.在不同的初始缺陷和加载过程的情况下,薄膜的后屈曲过程会出现连续的二次屈曲现象.二次屈曲过程中薄膜可能是稳定的也可能是不稳定的,与初始缺陷及加载过程有关.