Dynamic centrifuge modeling of an isolated footing for transmission line tower

Parameters which influence the settlement of the tower of transmission line are evaluated. Dynamic centrifuge tests and tests for obtaining fundamental properties of sand satured with different pore fluids (water, 50cst silicon oil) are carried out. The letter tests indicate:(i) In cyclic triaxial tests, there is no difference between the samples satured with water and silicon oil:; (ii) To satisfy the law of similarity, it is preferable to use silicon oil instead of water in centrifuge tests.(AU)

Soil force on conduit pile system due to liquefaction-induced lateral flow

The present study discusses the soil force of liquefaction-induced lateral flow on a conduit-pile system. For this purpose, the model shake table and the static load test were conducted. The soil force on the pile is possible to estimate utilizing a drag force, though some difficulties exist in design prqactice. On the other hand, the lateral earth pressures on the conduit is found to be unbalanced loading between upper and lower stream sides. Moreover, the degree of the inequality of the upper and lower sides depends on pile flexural stiffness and length. It is stressed that the correlation enables us to determine the soil force of lateral flow. Using the correlation, a tentative design procedure is developed to estimate lateral bearing capacity of pile.(AU)

Damage to water pipes during the 1994 Northridge earthquake

This paper presents damage to pipes of a water supply network system under the control of the Department of Water and Power of City of Los Angels(LADWP). Site investigation was conducted at San Fernando Valley where the damage to trunk lines, distribution pipes and service pipes were concentrated. Sixteen breaks of large diameter trunk lines and approximately 1.670 breaks of small diameter distribution pipes and service pipes were damaged during the earthquake. The damage to the trunk lines contains breaks of joints and pipes of an oldriveted trunk line buried along Roscoe Street, which breaks were occurred just over or very close to the epicenter. Other typical damage to the trunk lines were telescopic crashes and failures in tension of welded bell joints due to slight permanent ground movement at Balboa Boulevard. Most of the breaks of small diameter distribution pipes were caused to old and weak gray cast iron pipes connected with sockets and spigot joints, whose flexibility or strength against dynamic and permanent ground movement could not be expected. And the breaks include those of the service pipes were concentrated in Northridge district including Granada hills, San Fernando district and Sherman Oaks district.(AU)

Experimental study of effects of liquefaction - induced ground displacement on in - ground structures

The authors have conducted the following experiments to investigate the fundamental characteristics of the effect that liquefaction-induced ground displacements have on in-ground structures: (i) experiments to measure the pressure of liquefied soil on a rigid in-ground wall (ii) experiments to measure the effects of liquefaction-induced ground displacements on a pile (iii) experiments on the load acting on spheres moving in liquefied soil. From these experiments it was concluded that the pressure exerted by liquefied soil on a rigid in-ground wall was approximately equal to the pressure of a liquid with an equivalent specific gravity. The force due to laterally flowing ground on in-ground structures did not depend on the magnitude of the ground displacement, but was greatly affected by the flow velocity.(AU)

The state of the art in mitigation of liquefaction for lifeline facilities in Japan

In Japan, studies on the mitigation of liquefaction have been carried out since the 1964 Niigata earthquake. As a countermeasures against liquefaction, a compaction method such as the Sand Compaction Pile Method has generally been employed for the foundations of fuel tanks. Recently, various points of in-situ soil improvement methods have been put into practical use. This paper reviews the following three items: 1) The present state of the in-situ soil improvement methods designed to reduce liquefaction in Japan, 2) The latest research on the utility lines and manholes used in the lifeline facilities, 3) Design, construction methods, and examples of the application of the Sand Compaction Pile Method, the Gravel Drain Method, and the Deep Mixing Method.(AU)