Thamer Ahmad Mohammad Ali

Clear-Water Local Scour around Pile Groups in Shallow-Water Flow

The results of an experimental study on clear-water scour at pile groups under steady flows at threshold velocity are presented. A wide range of pile group arrangements, spacing, and submergence ratios are studied. Uniform bed material in a 46-m long, 1.52-m wide, and 1.9-m deep flume was used to obtain comprehensive data. Empirical relations to demonstrate the effects of the studied variables are presented. On the basis of the findings of this study, a new method to predict the effect of pile group arrangements, pile spacing, and submergence ratio on local scour depth is proposed. The experimental data obtained in this study and data available from the literature are used to evaluate predictions of existing methods and the accuracy of the proposed method. The proposed method gives reasonable scour depth predictions.

Influence of Cement – Sodium Silicate Grout Admixed with Calcium Chloride and Kaolinite on Sapric Peat

Abstract Sapric peat is extremely soft, unconsolidated and has high organic content. It is most decomposed peat with less fiber content among all peats. This paper investigates the effectiveness of using different ratios of cement–sodium silicate system grout compounds with kaolinite in mechanical property (shear strength) and micro–structural properties (SEM and EDX) of sapric peat samples after 3 and 30 days of curing. The study showed that the kaolinite was effective in increasing the shear strength and reducing the moisture content of the treated peat. Calcium chloride seemed to have different effects on the grouts strength. It caused to increased shear strength of samples until the net charge of the sample changed to zero and then it decreased with further increase in calcium chloride. By increasing sodium silicate (within 3%), cement and soaking time on treated peat, it was observed that they are able to increase the shear strength and density with a corresponding decrease in moisture content, porou...

Effect of discontinuities on the stability of rock blocks in tunnel

This paper presents the results of an investigation that was carried out using important parameters, such as discontinuities in forming rock block and instability in tunnel. Discontinuities like bedding and joints are one of the most important factors when compared with parameters, such as engineering features of rock mass. In this review, numerous features like rock quality designation (RQD), rock classification (RMR), stress and strain and distributions of discontinuities in a sample tunnel were evaluated. However, most of them were suitable in the tunnel, but because of the creation of more intersection points in critical zone, the movement of blocks in tunnel roof and wall of the tunnel are possible. It also demonstrates simple factors such as step-over joints in rock mass, having important effect in instability.

Preventing landslides in times of rainfall: case study and FEM analyses

Purpose – The purpose of the paper is to present a new method of controlling through susceptible slopes in order to reduce the risk of landslides.Design/methodology/approach – Geotechnical and geological characteristics were collected and different FEM analyses were carried out in a case study of the Alasht valley in Northern Iran in order to determine susceptibility to landslides and consider appropriate countermeasures. Gravel drain piles have a real feel of reducing the pore water pressure in times of seismic loading, so they are used as a remediation method. The results clearly show their effects and an increase in safety as a result.Findings – Since the water table situation has a significant effect on stability, the present study focused on an example of using a seepage controlling system and its effect on the safety factor for different slopes in the area of Alasht, Northern Iran. Several FEM analyses were carried out on a landslide susceptible case. The results from FEM analysis of different slope...