Collision Of Blocks Research Articles

組積剛体系の衝突転倒振動の計算法 : その 2 3 方向地動による立体振動

Computational methods are discussed for analysing nonlinear dynamic response of columns consisting of stacked block elements. As well as previous report (Part I : Dynamics within Vertical Plane) each element is treated as a rigid body. In that report the analytical model considers a series of columns placed in a vertical plane with boundary structures. In the present report columns and boundary structures need not be placed in a vertical plane. Two dimensional dynamic analysis of Part I is extended to three dimensional one. The characteristics and assumptions of the method are as follows : (1) Blocks move as rigid bodies and the upper and lower blocks are connected at one corner point. (2) Blocks are allowed only to rotate around two horizontal axis, and restricted neither to slip nor twist on the contact surface. (3) The principle of conservation of translational and rotational momenta is applied for the movements of blocks. (4) The collision theory based on a coefficint of restitution is applied for the collision of blocks. (5) 3-dimensional seismic excitation is available for two horizontal and one vertical directions. Theoretical equations such as equations of motion or equations of velocity change are derived from these assumptions. By using these equations, preliminary computer code "COLLAN 3" has been developed selecting appropriate numerical method such as Newmark's β=0 method as numerical integration. Several simple examples are presented to show feasibility of the code. These are free vibration of single prisms and forced vibration of stacked column surrounded by walls.

Collision-deformed Paleozoic continental margin, western Brooks Range, Alaska

A structural sequence of Carboniferous, Permian, and Triassic argillaceous and cherty rocks in the northwestern Brooks Range, herein named the Kagvik sequence, is a key to the tectonic history of Arctic Alaska. The Kagvik sequence lies structurally below thrust-faulted sheets of coeval carbonate rocks, including the Lisburne Group, and structurally above quartz mica schist and greenstone of the southern Brooks Range. Sedimentary features of the shelly fossil-rich carbonate strata of the Lisburne in the upper thrust sheets indicate deposition in a shallow-water shelf environment. The underlying shale and chert of the Kagvik is an attenuated section about 500 m thick repeated by imbricate thrusts. Ubiquitous pelagic fossils (radiolaria and Nereites trace-fossil assemblages) and volcanic material locally forming andesitic tuff and flows point to an oceanic environment of deposition. The presence of some limestone turbidites interbedded with the ocean-floor sediments of the Kagvik suggests that a carbonate shelf was nearby and that a south-facing continental margin existed during late Paleozoic and early Mesozoic time near the present-day southern Brooks Range. Collapse of this long-standing continental margin appears to be related to collision and accretion of Paleozoic island arcs and microcontinental blocks now represented by the metamorphic terrane along the south flank of the Brooks Range. The structurally higher thrust slices of mafic and ultramafic rocks emplaced on top of the collapsed continental margin represent ophiolitic basement of the Yukon-Koyukuk basin.

Indo-Australia: A comparison of some palaeomagnetic results from India with those from Australia

Indo-Australia: A comparison of some palaeomagnetic results from India with those from Australia