Pull-Out Resistance of Sand-Geosynthetics Reinforcement

Geosynthetics are widely used in earth retaining structures such as steep slope and earth retaining wall. The stability of the earth retaining structures depends on the interaction between geosynthetics and soil at the reinforced area known as reinforcement mechanism. The reinforcement mechanism of the soil reinforced structure usually difficult to be analysed thoroughly. It is because the preliminary study on the pull-out resistance and durability of the reinforcement material is not taking into account before it has been used to the site location especially in Malaysian practises. Less supervision and the assessment after the installation of the reinforcement materials also contributed to the failure of the soil reinforcement. In this paper, the laboratory model was used to imply the real condition of the soil reinforced structure using pull-out test. A standard pull-out test was carried out by using geotextile and geogrid reinforcing elements embedded into silica sand of size D50=1.357 mm and D50=0.571 mm subjected to normal pressures of 100 kPa, 150 kPa and 200 kPa. Comparative result and analysis showed that the geotextile reinforcement give more resistance rather than geogrid reinforcement under high normal pressure.

A Review on Finned Pile Foundation

Foundation is that part of the structure which supports and transfers the loads from the structure to the soil. Pile foundations are subjected to both axial and lateral loads especially in quay walls, harbour structures, offshore structures, earth-retaining structures, bridges, power stations, lock structures, tall chimneys, and high-rise buildings. Foundations for offshore structures are subjected to environmental loads from waves, currents and wind giving rise to lateral loads that could be up to one third of the vertical loads. In order to enhance the lateral capacity of pile of such structures finned pile can be used. Experimental and numerical analysis of finned pile in sandy and clayey soil is studied by various researches and they concluded that the lateral capacity can be improved compared to that of regular piles. This paper discusses the various parameters of finned pile that influence the lateral capacity of pile foundation. The various parameters discussed are position, number, inclination, shape and dimensions of fin. From the literatures it was found that rectangular fins show better lateral resistance than triangular fins and also as the length and width of the fin increases the lateral capacity of pile also increases in both sandy and clayey soil under lateral loads.

The Effect of Targeted Field Investigation on the Reliability of Earth-Retaining Structures in Passive State: A Random Field Approach

In one of their recent works, the authors examined parametrically the effect of targeted field investigation on reducing statistical uncertainty in active state analysis of earth retaining structures based on 2165 different cases for each of the sliding and overturning modes of failure. This analysis indicates that the optimal sampling location is always adjacent to the wall, while a sampling domain length equal to the whole height of the wall is suggested to be considered. The present paper deals with the “symmetrical” problem of soil under the passive state of stresses. Working in a similar manner, 1879 passive state cases have been considered (also for each of the sliding and overturning modes of failure) in a Random Finite Element Method (RFEM) analysis framework, where soil properties are modeled as random fields while measurements are modeled by sampling from different points of the field domain. The “actual” resultant earth passive pressure force (or moment) exerted by the random soil on the retaining wall is compared against the respective “predicted” one calculated using the soil property values sampled from the random field. Failure is considered to have occurred when the derived “actual” force is smaller than the respective “predicted” force. This analysis clearly indicates that the passive state constitutes a different problem, where the optimal sampling distance from the wall is half the wall height. Regarding the depth of exploration, it was again found to be the entire wall height. In addition, the present analysis shows that, the benefit from a targeted field investigation is much greater than the benefit gained using statistical methods for obtaining cautious estimates for the various soil properties; the latter refers to the “characteristic value”, a concept commonly used in the Limit State analysis framework of Eurocode 7.