Buried Structures


Book Description

Much of the infrastructure of modern society is buried below ground. Pipeline, conduits and culverts carry the services on which our economies depend and the strength and resilience of such structures is of vital importance. Larger underground construction is becoming more common in cities and towns, and in defence installations. This book brings t










Multiple-wheel Heavy Gear Load Pavement Tests


Book Description

Flexible and rigid pavements were constructed and tested to obtain data on pavement and soil behavior under large aircraft loadings for use in developing criteria for evaluating and designing airfield pavements subjected to multiple-wheel heavy gear loads (WMHGL). The test sections incorporated instrumentation systems designed to determine the response of the pavement structures to static, dynamic (slowly moving), and vibratory loads and to traffic by full prototype loadings of a 12-wheel assembly (one main gear of a C-5A aircraft), a twin-tandem assembly (one twin-tandem component of the Boeing 747 assembly), and a single wheel. Analysis of static load response data from the flexible pavement instrumentation program resulted in the establishment of maximum elastic deflection and vertical elastic stress versus depth curves. Comparisons showed that the same relationships were true for static and dynamic load tests, as well as for speed tests. The findings for the rigid pavement test section indicated that the Westergaard algorithm can be used for reasonable predictio of pavement response to test loadings. The data from the instrumentation program and the traffic tests were used in the analysis of the flexible and rigid pavement test sections. The analysis resulted in a modification of the basic flexible pavement CBR design method. (Author).




Influence of Backfill Properties on the Collapse of Pipes Under Dynamic Loads


Book Description

Important to the successful stemming and containment of underground nuclear explosions is the ability of ground shock pressures generated by an explosion to collapse the line-of-sight (LOS) pipe for a significant distance from the zero point. Prior to this study, the influence of the strength and density of the various grouts used to couple the steel LOS pipe to the parent rock on the collapse of the LOS pipe was not known except in general qualitative terms. Dynamic tests were conducted on a copper tube embedded in grouts of various physical properties and explosively loaded by a traveling detonation wave. The grouts were chosen to be representative of those used at the Nevada Test Site and to provide a significant range of strength and density. All tests were conducted underwater to ensure explosive coupling and to facilitate measurement of the dynamic pressures generated by the explosion. A theoretical analysis of a typical test cross section was made assuming the tubing and the grouts to behave as rigid plastic materials and the traveling load to be stationary. (Modified author abstract).