The study area was geologically investigated by many authors such as [2] - [15] , and others. Few engineering and geotechnical investigations were conducted on the studied area like engineering geophysical study to evaluate the geotechnical behavior of the soils at Tiba city [16] , investigation of rock deterioration in the Royel Tomb of Seti I, Valley of The Kings, Luxor [17] , engineering geophysical study at New Qena city north the study area [18] , engineering classification of the soils exposed along Upper Egypt-Red Sea road north of the study area [19] , geotechnical evaluation study of Pliocene sedimentary rocks exposed along Qena-Safaga road north of the study area [20] , and geotechnical evaluation of the sub-grade soils at the Cemeteries area, New Tiba city [21] .

The present work is concentrated on the geotechnical behavior of the sub-grade soils of the connector road at new Tiba city to classify these soils and to determine their proportionality for constructing the road at the study area. This study focused also on an exploration of the problematic soils especially the fine grained soils to suggest the favorable treatment.

The study area is located about 10 km to the east of Luxor city and about 50 km to the south of Qena city. It lies between latitudes 25˚43⁻N and 25˚46⁻N and longitudes 32˚45⁻E and 32˚47⁻E (Figure 3 and Table 1). The area has a wide variety of sediments belonging to the Upper Cretaceous-Lower Tertiary succession

as well as the Pliocene-Recent sediments [15] . The surface of the study area is covered by Quaternary sediments in the form of alluvial sands, gravels, clays or mud, and Wadi deposits. The studied soils are distributed in the study area as showed in a geological map (Figure 3). The studied area is located at the border between the eastern desert and the Nile valley. The area surrounding the New Tiba city is dissected by several structurally controlled large Wadies (valleys) like Wadi Madamoud to the south of this city, Wadi Banat Biri and Wadi Khozam. The directions of these Wadis are running from the southeast to the northwest dependent the main fault trend in the area.

Sixty three samples were collected; sixty disturbed samples collected from six mechanical drilling boreholes, from the surface to ten meters depth including one sample each one meter depth, to carry out the grain size analyses and plasticity tests. As well as, three undisturbed samples, each sample having thirty kilometers weight, collected at 0.5 m depth open pits near borehole no. 2 (clayey sand sample), near borehole no. 3 (poorly graded sand sample), and near borehole no. 5 (poorly graded gravel sample). The undisturbed samples were collected to carry out the chemical and mineralogical analyses as well as free swelling, proctor, and California bearing tests. The studied soils were belonging to the Quaternary age (Table 1 and Figure 4 & Figure 5).

Six wash mechanical drilling boreholes were conducted to collect sixty studied disturbed samples (Figure 6). Three 0.5 m depth open pits were done to collect three undisturbed samples. Five geotechnical tests including grain size analysis [23] [24] , plasticity [25] , proctor [26] , California bearing ration (CBR) [27] and free swelling percent [28] were carried out on the studied soils. Chemical (X-ray fluorescence, XRF, type of the instrument is JEOL, JSX 3222, Japan) and mineralogical (X-ray diffraction, XRD, PW1710 BASED diffractometer with a generator

operating at 40 KV, 30 mA) analysis of the studied clayey sand soil and some representative gravel pebbles were also applied to determine the geological origin and the sources of these gravels. Total dissolved salts, dissolved sulfate, and chloride were measured. The dissolved sulfate content was measured using Spectrophotometer (Cecil C/7400). The dissolved chlorides content was measured using the calibration method using a silver nitrate solution and potassium dichromate guide. Hydrogen ion concentration (PH-value), calcium carbonate, and total carbonate contents were also determined by the calibration method using sulfuric acid with phenolphthalein guide to estimate the chemical aggressiveness of the studied soils. As well as, Petrographical examination of the studied representative pebbles (gravels) using polarized light microscope was conducted to describe the lithology. The representative gravel pebbles were selected according to the difference of the lithology of the hand specimens.

Table 2 illustrated the XRF results of the three undisturbed samples near B2, B3, and B5. XRF results pointed to that the studied Quaternary gravels were mainly composed of silica (about 68.18%), calcium (about 13.27%). The poorly graded sands were mainly composed of silica (85.53%), aluminum (6.90%). The clayey sands were mainly composed of silica (59.22%), aluminum (10.45%) and iron (11.60%). The XRD results point to that the studied Quaternary gravels were composed of quartz, calcite and albite as major components and of gypsum and kaolinite as minor. The studied sands were composed of quartz, orthoclase,

albite as main components and anhydrite as traces. The results showed also that the clayey sands were composed of quartz, albite as major components and illite, montmorillonite, gypsum, and hematite as minor components. The results showed that the dissolved sulfate content of studied gravels, sands, and clayey sands is 120, 85, and 99 ppm, respectively. The dissolved chloride content is 490, 630, and 550 ppm, respectively.

The results also illustrated that the PH-value of the studied gravels, sands and clayey sands is 8.4., 8.1, and 7.9, respectively. The calcium carbonate content of the studied gravels, sands, and clayey sands is 0.62, 0.50, and 0.29 ppm, respectively. The total carbonate content of the studied gravels, sands, and clayey sands is 1.05, 0.88, and 0.40 ppm, respectively. Depend on the PH-value, calcium carbonate and total carbonate contents; the chemical aggressiveness of the studied gravels, sands, and clayey sands is moderately aggressive for both gravels and sands and highly aggressive for clayey sands soils.

Figure 7 showed the grain size distribution curves of the studied samples. The results of the grain size distribution test of the studied soils showed that the gravel samples were classified as poorly graded gravels (GP) according to unified soil classification system (USCS) where the gradation parameters of the studied gravels including coefficient of uniformity (Cu) were less than 4. Sand samples especially at boreholes no. 4, 5, and 6 were classified as well graded sands (SW)

according to USCS specifications. The sands samples at borehole no. 1, 2, and 3 were classified as poorly graded sands (SP) where the gradation parameters of the studied sands including coefficient of uniformity (Cu) were less than 6.

The results pointed to the clayey sands samples were classified as SC according to USCS, the percent of clay was ranging from 17% to 24%. According to American association of state highway and transportation official (AASHTO), SW samples were classified as A1-a group and SP samples classified as A1-b, they described as excellent to good subgrade soils. On the other hand, SC samples were classified as A2-7 group and described as fair to poor subgrade soils.

The plasticity test results showed that the plasticity index (PI), which equal to the difference between liquid limit (LL) and plasticity limit (PL), of the clayey sands samples was ranging from 15% to 17%, they are medium plastic clayey sands. Liquid limit (LL) and plastic limit (PL) were ranging from 41% to 44% and from 26% to 27%, respectively. The clayey sands samples described as medium plastic (Table 3 & Table 4).

The Modified Proctor Test was carried out to determine the maximum dry density (MDD) (Proctor density) and the optimum water content (OWC) of the studied undisturbed samples. Three selected undisturbed samples at 0.5 m depth were tested according to [26] . The test results are listed in Table 4.

The results of California bearing ratio (CBR) test pointed to that CBR-unsoaked

values of the investigated clayey sands soils were ranging from 10% to 14%, in contrast CBR-soaked (4 days water soaking) values of these soils were ranging from 2% to 7% (Table 4 & Table 5). The quality of the sub-grade clayey sands is described as very poor to fair according to [29] .

Free swelling test results illustrated that the free swelling percent of the studied clayey sands undisturbed samples was ranging from 30% to 80%. The most tested clayey sands samples having free swelling percent more than 50%, they are classified as low to medium expansive soils according to [28] (Table 4 & Table 6).

Petrographical examination of the hand specimens and some representative studied gravels pebbles under the polarized light microscope, showed that the examined pebbles were composed of igneous rocks (like granite, rhyolite, gabbro, andesite), metamorphic rocks (like gneiss), and sedimentary rocks (like crystalline limestone, organic limestone, flint, and calcareous sandstone).

The study Quaternary gravels were mainly composed of silica (about 68.18%), and calcium (about 13.27%). The poorly graded sands were mainly composed of silica (85.53%) and aluminum (6.90%). The clayey sands were mainly composed of silica (59.22%), aluminum (10.45%), and iron (11.60%). The studied gravels

were composed of quartz, calcite, and albite as major components and of gypsum and kaolinite as minor. The studied sands were composed of quartz, orthoclase, and albite as main components and anhydrite as traces. The clayey sands were composed of quartz, and albite as major components and illite, montmorillonite, gypsum, and hematite as minor components. The gravels pebbles were composed of igneous rocks (like granite, rhyolite, gabbro, andesite), metamorphic rocks (like gneiss), and sedimentary rocks (like crystalline limestone, organic limestone, flint, and calcareous sandstone). The minerals and chemical compositions of the studied soils in addition to the lithology pointed out that the sources of the studied gravels pebbles were the basement complexes along the red sea coast and the Upper Cretaceous-Lower Tertiary succession. A vertical cross section along the study road in X-Y direction was achieved by a correlation between the studied six mechanical drilling boreholes data. This vertical cross section showed that the studied area along the axis of the connector road is composed of four intercalated Quaternary layers of sediments. The succession included lenses and tongues of the clayey sands, surface clayey sands lens is at borehole no. 2. Additionally, there are two subsurface tongues of clayey sands at boreholes no. 1 (2 m depth), and at boreholes no. 5 and 6 (5 m depth). There is underground water observed until the drill depth end (10 m).

The gravel samples were classified as poorly graded gravels (GP) according to unified soil classification system (USCS) where the gradation parameters of the studied gravels including coefficient of uniformity (Cu) were less than 4. Sand samples especially at boreholes no. 4, 5, and 6 were classified as well graded sands (SW) according to USCS specifications. The sands samples at borehole no. 1, 2, and 3 were classified as poorly graded sands (SP) where the gradation parameters of the studied sands including coefficient of uniformity (Cu) were less than 6. The results pointed to the clayey sands samples were classified as SC according to USCS, the percent of clay particles was ranging from 17% to 24%. According to American association of state highway and transportation official (AASHTO), SW samples were classified as A1-a group and both SP and GP samples classified as A1-b, they described as excellent to good sub-grade soils. On the other hand, SC samples were classified as A2-7 group and described as good to fair sub-grade soils.

The plasticity index of the clayey sands which occurred as one lens and two tongues at the studied area was ranging from 15% to 17%. The clayey sands samples described as medium plastic soils. Depend on the PH-value, calcium carbonate, and total carbonate contents, the chemical aggressiveness of the studied gravels, sands, and clayey sands is moderately chemical aggressive for both gravels and sands and highly chemical aggressive for the clayey sands soils. CBR-soaked (4 day’s water soaking) values of the clayey sands soils were ranging from 2% to 7%. They were classified as very poor to fair sub-grade according to [29] . The free swelling percent of the studied clayey sands was ranging from 30% to 80%. Most of the studied clayey sands samples had free swelling percent more than 50% corresponding to [28] . They were classified as low to medium expansive soils according to [28] . The sub-grade at boreholes no. 1, 3, 4, 5, and 6 (Gravels and Sands) was good to excellent. The sub-grade at borehole no. 2 (Clayey sands) was poor to fair. The clayey sands are expansive soils and may be lead to a heave of the road at borehole no. 2. Finally, the studied clayey sands samples are problematic sub-grade soils and described as medium plastic, highly chemical aggressive and low to medium expansive soils and classified as poor to fair sub-grade soils. Finally, the present work provide that the Quaternary sediments like the present investigated soils characterized by rapid lateral and vertical changes in the lithology and texture that means each different project area in the Quaternary sediments need to a special geotechnical subsurface exploration program to investigate the Quaternary soils in details and to suggest the suitable soils reclamation and the suitable foundations design.

To avoid the engineering problems due to the problematic clayey sands sub-grade of the road especially at borehole no. 2, one of the following treatments can be applied:

1) Replacement the expansive clayey sands sub-grade with imported well graded gravels or imported mixture of well graded gravels and sands percent (50% gravels plus 50% sands). The thickness of replacement must be at least 50 cm. Compaction of the imported materials in two layers each layer has 25 cm thickness, until they reach to at least 97% of the modified maximum proctor density.

2) Chemical stabilization of the problematic clayey sands soil sub-grade at B2 using cement kiln dust (by-product) or mixture of cement kiln dust with lime.

3) Mechanical stabilization including compaction of the clayey sands soil sub-grade at B2 using Geotextile technique to prevent the lateral displacement of the soils especially in case of rainfall or arrival the water to the sub-grade soils.