Foundation Failures Associated with Salt Rock and Surrounding Coastal Plain

A detailed investigation has been conducted to study the causes of severe and widespread damages in a town situated on a salt dome. The study includes a thorough assessment of ground conditions in the coastal plain surrounding the salt dome for possible utilization of the plain as redevelopment areas. Major geological features in the study area comprised of collapsible windblown sands which are underlain by salt rock in the old town and soft/loose sabkha deposits in the proposed redevelopment zones. It has been found that the extensive damages in the buildings and roads are primarily due to subsidence phenomenon associated with the dissolution of salt rock. The properties of the sabkha sediments and anticipated geotechnical problems have been described

Laboratory simulation of field preloading on Jizan sabkha soil

Jizan sabkha soil is characterized by being highly compressible with low bearing capacity. It cannot support a structure load without soil improvement. Preloading by embankment fill is one of the practical and economical methods to enhance the sabkha soil properties. Embankment fill of 3 m high with a pressure intensity of about 50 kPa is found to be adequate to achieve the required improvement. Simulation of preloading by laboratory consolidation test following a special loading sequence reasonably approximates the field settlement. The predicted settlement based on consolidation results is found to be close to the directly measured field settlement using the preloading technique. The pressure intensity and time of loading by embankment fill can be predicted by laboratory testing. In this research, the embankment preloading using a 3 m fill applied in two or three stages and sustained for about 6 months is found to be effective to improve the soft sabkha properties

Heave Prediction Techniques and Design Consideration on Expansive Soils

Expansive soil has been responsible for many structural damages that result in great financial losses in many parts of the world including Saudi Arabia. Reliable prediction of ground heave is essential for the development of more effective and economical design of structures on expansive soil. Three procedures are commonly used for this purpose; oedometer test method, suction technique and empirical relationships. Available methodology for the prediction of swell potential in expansive soils and techniques proposed for quantitative analysis of heave are presented in this paper. Also, alternative soil treatment methods to minimize swell potential of expansive soils or foundation design criteria to safely accomodate ground movements are discussed herein

Heave prediction techniques and design consideration on expansive soils

Civil Engineering Department, College of Engineering, King Saud University, P.O. Box 800, Riyadh 11421, Saudi Arabia Phone: +(966-1)467‑77038 Email: [email protected] soil has been responsible for many structural damages that result in great financial losses in many parts of the world including Saudi Arabia. Reliable prediction of ground heave is essential for the development of more effective and economical design of structures on expansive soil. Three procedures are commonly used for this purpose; oedometer test method, suction technique and empirical relationships. Available methodology for the prediction of swell potential in expansive soils and techniques proposed for quantitative analysis of heave are presented in this paper. Also, alternative soil treatment methods to minimize swell potential of expansive soils or foundation design criteria to safely accommodate ground movements are discussed herein

Preloading for reduction of compressibility characteristics of sabkha soil profiles

Sabkha soils are coastal and inland salt flat deposits of arid climates, which invariably contain an appreciable amount of organic materials. They are, therefore, characterized by being highly compressible with a significant part of the settlement taking place as secondary compressions. In this study, the applicability of a preloading technique in improving the compressibility characteristics of sabkha sediments was investigated through construction of an instrumented test embankment on a typical sabkha formation from the southwest coast of Saudi Arabia. Settlement and pore pressure measurements were taken for an observation period lasting 1 year. Compressibility parameters were determined in the laboratory from extensive standard and long-term consolidation tests on undisturbed samples taken from the site before and after the preloading process. The laboratory test results substantiated by the relatively large settlements measured under the test embankment indicate that the precompression method is an effective technique that can eliminate the primary consolidation settlements and reduce the secondary compressions of sabkha sediments. The field behavior was predicted utilizing the conventional theory of consolidation and the finite element method. Using laboratory-determined compressibility parameters, the one-dimensional theory of consolidation highly overestimated the measured settlements and significantly underestimated the observed settlement-time behavior. However, close agreement between observed and predicted behavior was obtained when field parameters were used in the analyses. Although substantially overestimating the time required for completion of primary settlements, the finite element predictions of the magnitude and the rate of settlements are considered satisfactory.Corresponding Author: Prof. Mosleh A. Al-Shamrani, Professor Geotechnical Engineering, College of Engineering, Department of Civil Engineering, King Saud University, Riyadh, Saudi Arabia. Email: [email protected]

Swell Behavior of Expansive Soil with Free Lateral Movements

Expansive soils are characterized by volume increase upon saturation. Extensive damages to structures may occur as a result of soil heave. Prediction of field expansion is essential prior to foundation construction. Experimental tests using oedometer equipment are used to predict field swell. However, in these tests, full lateral expansion is restrained which does not represent the actual field behavior where part of volume increase is consumed in the lateral direction. To improve the quality of field swell estimation, different testing techniques must be adopted. In this paper, experimental testing program is carried out on expansive soil with no lateral restraint. It is found that the lateral swell constitutes about one third of the total swell. More attention should be directed to such unconventional testing procedure to replace the oedometer tests for more accurate heave prediction. Keywords: Expansive soil, Swell pressure, Swell index, Lateral restrain