This paper displays an empirical work of a micropile inserted in the dry river sand with different length to diameter (L/D) ratios (13, 15, 27, 42, and 50). The experimental work is executed on the models of micropile to imitate the side force motion, acting on the micropile head to explain the micropile conduct due to the different side force rates. Forty-five models are tested (eighteen models for short pile, eighteen model for long pile and nine models for intermediate) embedded in different relative densities of sandy soil.  The results illustrate that for the same relative density, the lateral load is decreased when the moving rate increasing from (3.37 to 3.97 then 4.59 mm/min), that means frequency (0.55 to 0.65 then 0.75 Hz), respectively. At the same moving rate of horizontal loading, the value of lateral load increased with the increase of horizontal displacement until reach to the 12mm at the end of the test. The duration of the test decreased with the increase of moving rate and the maximum duration of the test recorded for micropile model has (L/D) of 50 with 75% relative density when the moving rate of lateral load is 3.37 mm/min. Also, it is found that the duration of the test increases when the relative density increased at the same moving rate.

Geotechnical design and execution of civil engineering structures on soft to very soft soils are usually associated with substantial difficulties. These soils are sensitive to deformations and possess low shear strength values. Geotechnical properties of such soil stabilization are improved by various methods. Admixtures improve soil properties in order to form strong foundation capable of bearing loads of such structure. Clay soils cause cracking and fracture of pavement, rail ways, highways, embankment, foundations… etc. The main objective of this study is to discuss and evaluate the effect of addition of fly ash on shear strength of soft soil and bearing capacity of these soils by adding clay columns stabilized with fly ash in soft soils. The essential idea represents in investigation of possibility of using fly ash to reduce compressibility to find solution for some problems of failure in soft soils in Iraq. This will encourage the use of fly ash as stabilizer especially as it is an economic material and for its local availability. Soil used in the study was obtained from Al-Nahrawan City 35 km east of Baghdad. According to the Unified Soil Classification System, it is classified as (CL) soil. The soil consists of 3% sand, 35% silt, and 62% clay. The tests were carried out using a steel container with internal dimension of (400×350×300 mm). The steel container is made of steel plates that are 4mm in thickness. The thickness of the bed of clay was 300 mm, and 400 mm for (L/D) 4 and 6, respectively. The depth of the column was 200 mm and 300 mm for (L/D) 4 and 6, respectively, at 50mm diameter of column (D). Square steel foundation of 4mm thickness and width 60 mm was used in all the tests. The length to diameter ratio (L/D) which was used in this study was 4 and 6. The results of curing days in 14 days and 28 days are close to each other. The incensement ratio is about 5% between 14 and 28 days for the two (L/D) 4 and 6. (L/D) 6 has shown more improvement than L/D 4, the improvement in bearing ratio failure is about 30%.

This paper presents the effect of heat treatment on ultimate bearing capacity and total settlement of soft clay. The soft clay that was used in this study was prepared by mixing Baghdad's clay with sufficient water content which gives a shear strength of 7 kPa.Seven model tests were carried out on soft clay inside a cubic steel box of 750 mm side length after heat treatment, two of which were used as a reference without treatment for comparison. A special heating system was designed and manufactured for this purpose by using the gas as a source of heating through boreholes. Four square patterns casing boreholes having 3.5 cm in diameter and 30cm in length with spacing 3d, 4d, 5d, 6d and 7d (were d is the diameter of the borehole) and the time of heating was six hours for each model. A monotonic load was applied on an aluminum square model footing of 150 mm length and 20 mm thick placed on the center of surface area of the soft clay until the settlement exceeds 10% of the width footing. The results showed that the bearing capacity increases and the settlement decreases with spacing increasing until some limiting value (5d) then the bearing capacity decreases and the settlement increases. The 5d spacing is the best one where the bearing capacity increases nine times and the settlement decreases to one tenth compared with that without heating.

This paper presents the effect of spacing between boreholes heating on plasticity of expansive soils. The expansive soils used were prepared artificially by mixing Kut clay with different percentages of bentonite. Nine laboratory models of expansive soils having dry unit weight of 17.8 kN/m3 with 6% initial water content were prepared inside a steel box of (300 mm × 300 mm × 400 mm height).  A special heating system generates 400 Co for six hours was designed and manufactured for this purpose using 12 mm diameter electric heaters inserted through boreholes. Square pattern boreholes of 170 mm length with spacing (4.16d, 6.25d and 8.33d) were used. A representative sample were taken after heating from the center of the square pattern for measuring the plasticity of the soils. The results showed that the plasticity index remarkedly decreases compared with that before heating and increases with increasing bentonite and the spacing. It is also indicated that an expansive soil could be changed from high to low plasticity

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