Evaluation of Soil Engineering Characteristics in Jalalpur Region, Pakistan

This study deals with the evaluation of soil engineering characteristic along the proposed route of Jalalpur irrigation project. The proposed JIP (Jalalpur Irrigation Project) is located along the right bank of Jhelum River in Tehsil PDK (Pind Dadan Khan) and Tehsil Khushab of District Khushab. JIP is funded by ADB (Asian Development Bank). The JIP will enhance crop production in Tehsil PDKand Khushab. Famers will be benefited through JIP as they will get regular supply of water through canal. It will also create job opportunities for local people and will lead to the prosperity of the Project area. Detailed soil investigation along proposed route was carried out by M/S GEOBAND. Straight rotary method of drilling was used. The recovered soil samples and water samples were tested in laboratories. The detailed engineering analysis was performed and soil parameters along with bearing capacities are suggested. Results have indicated variations in SPT values along the proposed route. The top layer of soil along proposed route is mostly Silty Clay with variation along the depth. The proposed bearing capacity for shallow foundation is 1.25 ton/ft 2 (120 kN/m 2 ) at depth of 5ft (1.5 m) beneath footing, and for bored piles having diameter of 2.5 ft (0.76 m) at a depth of 50 ft (15 m) is recommended as 70 ton (685 kN). The results presented in this study will be helpful in deciding the detailed foundation design of the engineering structures along the proposed route of JIP.

The whole area is a waste crown land without irrigation water either from surface or ground water source, whereas the land has good potential for irrigated agriculture similar to lands adjoining the command areas of Eastern Sadiqia and Bahawal Canal Systems. The abandoned area of Hakra Branch is also a part of the Project Area.
The purpose of the study is to determine the sub-surface conditions, physical, mechanical and chemical properties of the investigated ground, and to recommend safe bearing capacities of the ground.

MATERIALS AND METHOD
The characteristics of soils were investigated by drilling boreholes along proposed alignment and in adjacent areas.
Standard penetration test along with permeability test was also performed in drilled holes. The samples collected from site investigation were tested in Laboratory.    Table 1.

Permeability Tests
Total forty-four (44) constant head permeability tests were performed in boreholes.

Laboratory Testing
The samples recovered from boreholes were tested in Laboratory. Grain size, chemical analysis, soil property, moisture content and direct shear tests were performed.

Field Investigation
Sub-surface stratification along the alignment of

Field and Corrected SPT N 60 Values
Graphical presentations of variation of SPT blow counts both for field and corrected "N 60 " [5] values along the proposed Canal alignment for ABH-10 and ABH-20 are shown in Fig. 2(a-b). The field result shows that SPT N

Shear Strength Parameters based on SPT N Value
SPT "N" field values have been corrected to N 60 with respect to overburden pressures and energy transfer.  Undrained Shear Strength (C u ) and Unconfined Compressive Strength (q u ) of Silty Clay/Clayey Silt has been estimated by using the empirical relationship [6]. Similarly, effective angle of internal friction () has been estimated [7] and average along depth is given in Table 2

Analysis of laboratory Testing
Grain analysis performed on recovered soil samples. Soil samples are classified as SP-SM, SW-SM, whereas most of the sample classified as SM and CL/ML [8]. Most samples have Plasticity Index between 10 and 20; therefore, there is medium swelling potential capacity of soil [9]. The values of specific gravity were found in the

Geotechnical Foundation Design Criteria
Following criteria is opted for estimation of bearing capacities: (i) Foundation should be safe against shear failure of the supporting ground. A factor of safety of 3.0 is adopted for this purpose.
(ii) Foundation should not settle excessively under the service loads. A limit of 25 mm has been put on the total settlement of individual foundations.

Bearing Capacity Curves for Shallow Foundation Based on SPT N 60
The summary of the average SPT N, N 60 and  along depth is given in Table 2 for boreholes along canal alignment.
Variation is observed in average SPT N 60 value along depth. Minimum 3 and Maximum 36 SPT N 60 is observed. The angle of internal friction from limited laboratory tests are also compared with estimated angle of internal friction from field SPT values.There is a good agreement between empirically and laboratory estimated angle of internal friction values with few exceptions. The bearing capacity curve has been developed for Silty Sand considering depth of foundation as 1.5m (Fig. 4) using Meyerhof's equations [10]. At this depth, the minimum and maximum SPT N 60 values among all boreholes are 1 and 17, with mostly values falling below 5. Therefore, SPT N 60 as 4 and  as 30 o is selected for bearing capacity curve [11].
Keeping in view variation in SPT N 60 values, it is highly recommended to use SPT N 60 values of a particular borehole in the vicinity of the proposed structure. The bearing capacity of 1.25 ton/ft 2 (120 kN/m 2 ) is recommended.

Bearing Load Curves for Deep Foundation (Bored Pile)
The bearing capacity of the pile for bored condition (RC piles under compression) has been determined (Pile Dia 2.5 ft (0.76 m) and 3.5 ft (1 m)) using modified version of Terzaghi's equation/NAVFAC DM 7.2 [12] for medium dense sand condition ( Fig. 5(a-b)). The depth of water is considered as 5 ft (1.5 m). Factor of safety adopted for the allowable bearing load is 3,=18kN/m 3 , N q = 10, N q * = 55,  = 30 0 and w = 9.81kN/m 3 . Skin resistance is considered as constant after 15 D (For medium dense sand). Bearing capacity is the summation of skin and end point resistance.
In addition to that, bearing capacity curves have been