Static response analysis of structures with interval parameters using the second-order Taylor series expansion and the DCA for QB

In this paper, based on the second-order Taylor series expansion and the difference of convex functions algo- rithm for quadratic problems with box constraints （the DCA for QB）, a new method is proposed to solve the static response problem of structures with fairly large uncertainties in interval parameters. Although current methods are effective for solving the static response problem of structures with interval parameters with small uncertainties, these methods may fail to estimate the region of the static response of uncertain structures if the uncertainties in the parameters are fairly large. To resolve this problem, first, the general expression of the static response of structures in terms of structural parameters is derived based on the second-order Taylor series expansion. Then the problem of determining the bounds of the static response of uncertain structures is transformed into a series of quadratic problems with box constraints. These quadratic problems with box constraints can be solved using the DCA approach effectively. The numerical examples are given to illustrate the accuracy and the efficiency of the proposed method when comparing with other existing methods.

Experimental investigation on basic law of rock directional fracturing with static expansive agent controlled by dense linear multi boreholes

Directional rupture is one of the difficult problems in deep rock mechanics and engineering.A directional fracturing method with static expansive agent controlled by dense linear multi boreholes is proposed.A physical experiment is designed and performed to investigate the basic laws of this method.The fracture initiation and propagation process,and the mechanism of directional fracturing are analyzed.The results indicate that a directional fracture is formed along the direction of boreholes layout through directionally fracturing with static expansive agents controlled by the dense linear multi boreholes.According to the variation of strain and the distribution of associated acoustic emission(AE)events and energy,the experiment can be divided into three stages.In the first stage,the static expansive agent expand slowly with no fracturing inside the rock.In the second stage,some initial micro-fracturing occurs inside the rock.In the third stage,a wide range of fracturing occurs inside the sample.The internal micro-fracturing planes are connected to form a macro-fracture.Finally,it propagates to the surface of the sample.The directional fracturing plane presents a relatively smooth plane with little bias but much local fluctuation.