Fly Ash Walls Research Articles

Numerical Studies on the Reinforced Fly Ash Wall in Tiered Configuration

This paper presents the findings of the numerical studies performed on a two-tiered reinforced fly ash wall. Fly ash was used as backfill material and jute geotextile was used as reinforcement as well as facing material. Wrap-around facing was used in which the jute geotextile was folded at the face. Three-dimensional models of fly ash walls showing offsets at varying distances between the two tiers and the length of reinforcement were prepared. The horizontal displacement on the wall face, tensile forces on reinforcement, and settlement behavior of the backfill wall were analyzed. Further, the wall model was scaled 10 times to generate large-scale fly ash models to understand the behavior of a life-size reinforced fly ash tiered wall. The displacement in the horizontal direction at the face of the wall reduced with the increase in length of the reinforcement and the distance between the tiers. The influence of the offset distance between the tiers on the tensile forces acting on the reinforcement was also investigated. The critical distance between the offsets was identified as 0.6 times the lower tier height. The tiered wall in the present study showed significant reduction in mobilized tensile force in the reinforcements especially at the lower tier as compared with a single (without tier) reinforced fly ash wall of the same height. The maximum tensile force for a single wall was observed to be 1.25 times and 5.35 times the two-tiered wall with D/L = 0.6 for upper and lower tiers, respectively, where D = distance of the offsets between the two tiers and L = height of lower tier. The safety factors were determined by using strength reduction factors. The factor of safety increased with an increase in the offset distance. Similar trends were observed for large-scale models.Practical ApplicationsJute geotextile reinforced fly ash models were analyzed using finite-element analysis. The results are relevant for the construction of fly ash wall reinforced with jute geotextile. The distance between the offsets was varied and a critical distance between the offsets was identified as 0.6L. The practical implication of the study is a reduced offset distance. The previous studies have identified a larger value of such distance. The current ratio for offset distance should be considered while designing the reinforced fly ash wall in tiered configuration. A change in position as well as value of tensile force acting on reinforcement was observed with the change in the distance between the offsets, thereby changing the location of failure plane. This should be taken in to account while designing the reinforcement for the wall.

Parametric studies on two-tiered model fly ash wall

ABSTRACT The multi-tiered wall is earth-retaining structure, similar to a reinforced wall, constructed by providing offsets between the tiers at a certain height of the reinforced wall. The current study makes an effort to employ fly ash as a backfill material for the multi-tiered reinforced wall. The behaviour of laboratory models has been studied. Single and two-tiered models were prepared for the study. The effect of the reinforcement length, reinforcement spacing and the offset distance between the tiers on the failure pattern, horizontal displacement and normalized surcharge pressure was determined. From the experimental investigation, it was observed that the critical offsets between the tiers of the wall increase due to the introduction of reinforcement, as offsets between the tiers, D was observed 0.4L and 0.6L for the wall model without any reinforcement and the wall model with reinforcement, respectively, where L is the lower tier height. The failure patterns were found to agree with the Federal Highway Administration (FHWA) guidelines for tiered wall except for the unreinforced wall model at the 0.4L offset distance. There was an increase in normalized surcharge pressure due to the introduction of jute geotextile reinforcement up to 68.75% at the 0.7H length of reinforcement, where H = total wall height. As the jute geotextile reinforcement length increases, the horizontal displacement of the wall facing reduces up to 98% as compared to unreinforced model whereas, the increase in spacing between the reinforcing layers increased the horizontal displacement of the wall facing.

Model Studies on Bamboo-Geogrid Reinforced Fly Ash Walls under Uniformly Distributed Load

AbstractDue to ever increasing urbanization and industrialization, the demand for power and electricity increases at a staggering rate. In order to address the demand for electricity, more advanced...

Behaviour of Bamboo–Geogrid Reinforced Fly Ash Wall Under Applied Strip Load

This technical note presents results of model tests performed on bamboo geogrid reinforced fly ash walls under applied strip load. The effect of vertical spacing and length of bamboo geogrid mattresses and strips on the deformation behavior of the model walls was studied and discussed. The results demonstrated the effect of increase in length and coverage ratios and decrease in vertical spacing of reinforcements on the improved performance of the model walls, including increased failure surcharge pressure, reduced facing displacement and backfill settlement. The failure surcharge pressure compared with the unreinforced model wall was improved by 185.76 and 311.84% for bamboo geogrid strips and mattresses respectively when vertical spacing and length of reinforcement used were 20 and 65% of the wall height respectively.

Effect of Reinforcement on Multi-tiered Fly Ash Wall

Fly ash is a by-product formed by the burning of coal in thermal power plants. In India, the generation of fly ash in the year 2014 to 2015 was 184.14 million tons. However, only 55.69% of the total fly ash was utilized. The disposal of fly ash is a major environmental concern. The present study aims at utilizing fly ash as backfill for the wall in a tiered configuration. A multi-tiered wall is a soil wall constructed in tiered configuration by providing offset at different elevations of the wall. The behaviour of multi-tiered wall is essentially affected by the critical offset distance which can be defined as the length of the offset beyond which the tiers of the multi-tiered fly ash wall start behaving as individual walls and there is limited interaction between the two tiers. There are very few studies on multi-tiered walls investigated by using laboratory model tests. Also, the studies of the behaviour of tiered walls utilizing industrial waste such as fly ash are limited. In the present study, laboratory model tests were conducted utilizing fly ash as backfill material and jute geotextile as reinforcement under strip loading. The two-tiered wall was modelled and the offset distance was varied as 0, 0.2L, 0.4L and 0.6L, where L is defined as the height of lower tier. The length of reinforcement was taken as 0.7H where H is the total height of the wall. Unreinforced and reinforced models were tested to determine critical offset distance, the effect of offset distance and reinforcement on different parameters governing the design of the tiered wall. From the observed failure pattern of model tests, it was found that inclusion of reinforcement increases the critical offset distance. The critical offset distance was found to be 0.4 times the height of lower tier for the unreinforced model and 0.6 times the height of lower tier for the reinforced model. The inclusion of reinforcement also reduces the horizontal wall facia displacement. Decrease in wall facia displacement was also observed with increase in the offset distance.

Model studies on cellular reinforced fly ash walls

In India, thermal power stations produce enormous quantity of fly ash as a byproduct of combustion. It requires huge disposal area and creates environmental problems. In India, where land to population ratio is too small, acquiring huge area of land for the disposal of fly ash is not easy. The utilization of fly ash and its disposal in an environment friendly manner is a foremost concern for developing country like India. In the present study, a series of model experiments were carried out for proper utilization of fly ash as an alternative backfill material in the cellular reinforced fly ash wall. Locally available waste plastic water bottles were used to prepare the cellular reinforcement. The diameter of bottles used for cellular reinforcement is 50 mm and with varying heights of 10 and 20 mm. The effect of change in length and spacing of the cellular reinforcement on the horizontal displacement of full height facing panel and settlement of the backfill were studied. For all the types of reinforcement cases, the variation in length and spacing of the reinforcement showed significant effect on the horizontal displacement of facing panel and on settlement of the backfill. The cellular reinforcement of height 20 mm showed better performance over 10 mm height cellular reinforcement.

Numerical Simulation Methods and Parameters of Geo-Grid Rein-Forced Retain Fly Ash Wall

Deformation of the geo-grid rein-forced retain fly ash wall and the reinforcing effect of geogrid reinforcement, depends largely on the role of interface properties between the geogrid and fly ash. Interface in the numerical simulation of the mechanical properties of the main elements reflected in the geogrid on the constitutive parameters,for example, shear stiffness,Cohesion,Modulus, reinforcement length and so on. In this paper, geogrid reinforced fly tangential stiffness, cohesion, elastic modulus, reinforcement length and other parameters on geogrid reinforced retaining wall deformation characteristics of fly ash for numerical simulation and comparative analysis,Obtained parameters on geogrid reinforced retaining wall mechanical behavior of fly ash, stability and reinforced the effect of law, Provide theoretical and analytical basis for the geogrid reinforced and reinforced fly ash characteristics of the interface wall wide application in engineering.