An Investigation of Excessive Seepage from the Al-Fulaij Recharge Dam, Oman

The Al-Fulaij recharge dam is located on the Al Batinah coast in Oman and was constructed in 1992. The dam is about 3.3 km long and 7.7 m high with a storage capacity of 3.7 million cubic meters of water. It is an earthfill dam with silty, sandy gravel fill in the embankment. Excessive seepage of between 5,000–12,500 m3/day was observed during floods in 1993, and several sinkholes were noticed close to the upstream toe. Remedial work consisting of an upstream blanket and a cutoff trench wall was performed in 2000. However, these remedial measures failed and almost the same seepage was noticed again during the impoundment. This paper investigates possible causes of the seepage using a finite element model. The input data for the model were collected from site investigations and field records during the construction and monitoring of the dam. The study reveals that the most probable cause of the excessive seepage is the presence of a permeable soil layer underneath the dam due to the dissolution of the gypsum material

Cation Distribution in Natural Chromites from Oman

Two specimens or natural chromite from the Oman ophiolite were studied using Mossbauer Spectroscopy (MS), X-ray Diffraction (XRD). and Scanning Electron Microscopy (SEM). The diffraction patterns obtained at room temperature showed that the two specimens have a face-centered cubic spinal structure. Their Mossbauer spectra at 295 K. 160 K and 78 K have been fitted to three doublets. assigned to two Fe 2+ at the tetrahedral (A1+,A2) sites and one Fe1+ at the octahedral (B) site. The ferrous-ferric ratio obtained from the Mossbauer analysis together with the atomic concentration derived from the microprobe data are used to derive the chemical formulae for the two specimens. The data also supports also supports  a model of ordered caution distribution in the specimens examined

An Investigation of Excessive Seepage from the Al-Fulaij Recharge Dam, Oman

The Al-Fulaij recharge dam is located on the Al Batinah coast in Oman and was constructed in 1992. The dam is about 3.3 km long and 7.7 m high with a storage capacity of 3.7 million cubic meters of water. It is an earthfill dam with silty, sandy gravel fill in the embankment. Excessive seepage of between 5,000–12,500 m3/day was observed during floods in 1993, and several sinkholes were noticed close to the upstream toe. Remedial work consisting of an upstream blanket and a cutoff trench wall was performed in 2000. However, these remedial measures failed and almost the same seepage was noticed again during the impoundment. This paper investigates possible causes of the seepage using a finite element model. The input data for the model were collected from site investigations and field records during the construction and monitoring of the dam. The study reveals that the most probable cause of the excessive seepage is the presence of a permeable soil layer underneath the dam due to the dissolution of the gypsum material

Towards Solutions of Seepage Problems

Flow rates are traditionally used for solving seepage problems in soils. In this paper, the method of fragments is presented as a good alternative for solving seepage problems. A user friendly and interactive computer program for the method of fragments has been developed. Several randomly selected problems are solved by the flow net method, the method of fragments and the finite difference method. It was found that the method of fragments and the finite difference method gave very close predictions of the quantity of flow, exit gradient and uplift force. Furthermore, the effects of different positions and lengths, and number of sheet piles, and upstream blankets on the values of quantity of flow, exit gradient and uplift force are examined

The formation of lithiated Ti-doped alpha-Fe2O3 nanocrystalline particles by mechanical milling of Ti-doped lithium spinel ferrite

The milling of spinel-related Ti-doped Li0.5Fe2.5O4 for different times is studied with XRD, Mossbauer spectroscopy and magnetic measurements. Milling converts the material to Li-Ti-doped alpha-Fe2O3 nanocrystalline particles via an intermediate gamma-LiFeO2-related phase. The role played by the dopant Ti-ion in the process is emphasized

Cation Distribution in Natural Chromites from Oman

Two specimens or natural chromite from the Oman ophiolite were studied using Mossbauer Spectroscopy (MS), X-ray Diffraction (XRD). and Scanning Electron Microscopy (SEM). The diffraction patterns obtained at room temperature showed that the two specimens have a face-centered cubic spinal structure. Their Mossbauer spectra at 295 K. 160 K and 78 K have been fitted to three doublets. assigned to two Fe 2+ at the tetrahedral (A1+,A2) sites and one Fe1+ at the octahedral (B) site. The ferrous-ferric ratio obtained from the Mossbauer analysis together with the atomic concentration derived from the microprobe data are used to derive the chemical formulae for the two specimens. The data also supports also supports  a model of ordered caution distribution in the specimens examined

Improvement in engineering properties of expansive soils using ground granulated blast furnace slag

Improvement in engineering properties of expansive soils by mixing ground granulated blast furnace slag (GGBFS) is the main focus of this research. For this purpose two expansive soil samples were collected from DG Khan and Sialkot areas (Pakistan). Classification tests revealed that DG Khan sample belonged to fat clay (CH) while Sialkot soil was lean clay (CL) as classified by Unified Soil Classification System. GGBFS has been added in varying proportions between 0 and 55% in these soil samples to study its role in stabilizing these expansive soils. Based on the laboratory test performed on composite soil samples, it was observed that maximum dry unit weight increased up to 10 % by adding 50% GGBFS in both samples. California bearing ratio (CBR) value showed an increase from 3.2 % to 11.5% for DG Khan soil while CBR values varied from 2.4% to 10.7% for Sialkot soil by mixing 50% GGBFS. Addition of 30 % GGBFS to DG Khan soil reduced swell potential from 8 % to 2 % while in Sialkot soil, 20 % addition of GGBFS reduced swell potential from 5 % to 2 %. Unconfined compressive strength of remoulded sample cured for 28 days increased by about 35% with the addition of 30%GGBFS. The results indicated that mixing of GGBFS in the expansive soil samples have a marked increase in their engineering properties. Also, it is an affective and environmental friendly means to dispose waste of steel industry