Geotechnical Investigations and Estimation of Earthquakes Factors at an Industrial Qift City, Qena, Egypt

The present work dealt with the estimation of geotechnical parameters and earthquakes factors of poultry feed factory project constructing at an industrial Qift city, Qena, Egypt. The geotechnical parameters were including gradation parameters, shear velocity (Vs), shear parameters (frictional angle and cohesion), and allowable bearing capacity. The earthquakes factors were including soil coefficient (S), limits of constant value for elastic response spectrum (TB and TC), and specified value for begin of the constant displacement spectrum (TD). The present study was interested also in an estimation of design ground acceleration (ag). To achieve these objectives, five mechanical wash boreholes were conducted at ten meter depth. Fifty disturbed samples were collected. Geotechnical laboratory tests were carried out like grain size analyses, direct shear box, and shear velocity (Vs). Standard penetration test (SPT) as geotechnical field test was conducted. The results showed that the studied soils were classified as well graded and poorly graded sands (SP and SW) according to the unified soil classification system (USCS). The earthquakes factors including S, TB, TC, and TD were 1.80, 0.10, 0.30, and 1.20 respectively. The ag-value of the studied area was 0.10. According to Egyptian code for vibration and dynamic load foundations, the studied project area was classified as low potential seismic. According to Egyptian code for shallow foundation, the allowable bearing capacity of the studied sands ranging from 1.5 to 3 kg/cm at shallow foundation width must be not less than one meter. Shallow foundations like isolated footing or structural mat were recommended.


Introduction
Industrial Qift city is one of the new industrial cities in Qena governorate; it was constructed to collect all the industrial activates in Qena region to encourage the investment and to contribute in the development of Qena city (Figure 1 & Fig-ure 2). The local geological conditions and shallow shear wave velocity structure of a site have a significant effect on earthquake ground motion. This effect is known as the site effect and may cause amplification of earthquake ground motion in frequency ranges unfavorable for buildings and structures especially in the presence of soft sedimentary covers overlying the bedrock (Mostafa et al., 2016). The seismic activity of Egypt is due to the interaction and the relative motion between the plates of Eurasia, Africa and Arabia. Within the last decade, some areas in Egypt have been struck by significant earthquakes causing considerable damage. Such events were interpreted as the result of this interaction (Sawires, et al., 2016). The present work is a try to deep understand the site effect including the soil type and its geotechnical behavior and its role in the seismic hazards assessment of the building construction at the study area. The construction of large projects and factories needs to evaluate the geotechnical behavior of the soils in the study area as well as to estimate the seismic hazard including the earthquakes factors and design ground acceleration. The present study area was investigated to determine the suitability of the study area and the soils to construct poultry feed factor at the industrial Qift city. The factory was designed only of two floors; it is considered as lightly loaded building ( Figure 3).

Scopes of the Present Work
The present study deals with the estimation of the geotechnical parameters of the studied soils including gradation parameters, shear parameters (ϕ & Cu), and shear velocity (Vs) to calculate the earthquakes factors of the studied soils and the design ground acceleration (a g ). That helps in determination of the seismic suitability of the studied area for constructing the poultry feed factory at an industrial Qift city. It also deals with calculation the allowable bearing capacity of the studied soils. The earthquakes factors are including soil coefficient (S), limits of constant value for elastic response spectrum (T B and T C ), and specified value for begin of the constant displacement spectrum (T D ). These earthquakes factors help the civil engineer to calculate the total base shear due to earthquakes (if happened) to design the project foundations to avoid the possible seismic damages.

Geological Setting
The investigated area is located at the east of Qift city, 20 km south of Qena city.
The coordinates of the studied area illustrated in  (Ismail, 2000). It is covered by Quaternary sediments in the form of Nile silt, Wadi deposits, and pre-Nile sediments. The studied soils are representative of pre-Nile sands named Qena Sand Formation (Pleistocene age). The area is surrounded by Pliocene deposits and Dawi Formation at both east and southeast directions. The distribution of the studied Quaternary sediments is showed in Figure 4. The studied area is located in a transitional zone between the eastern desert and the Nile valley. It is characterized by a simple topography follows the regional northwest slope towards the Nile. The area around the industrial Qift city is dissected by many large wadies like Wadi Matuli to the east and Wadi Khozam to the south. The courses of these wadis are running from the southeast to the northwest direction depending on the direction of dominant fault strikes and that pointed sure to that these wadis have structurally controlled origin. The study area is located at the recently stable tectonic zone.

Materials
Fifty disturbed samples were collected from five (B1 to B5) wash mechanical drilling boreholes (10 m depth); one sample was selected in each one meter   Figure 5). The studied soils were belonging to the pre-Nile sediments named Qena Sand Formation and having Quaternary age.

Methods
Subsurface exploration wash mechanical drilling according to (Egyptian Code, Part 2, 2001) was carried out to achieve five (B1 to B5) boreholes (10 m depth) and to collect the studied specimens ( Figure 6). One geotechnical test in the field during the drilling process named standard penetration test (

Wash Mechanical Drilling Results
Correlation between three boreholes data (B2, B3, and B4) was carried out to create a vertical cross-section of the studied area in XY-direction ( Figure 2). The lithology of B1 and B2 was similar to B3.The results showed that the area composed mainly of sands. From the surface to one to two meter depth, the soils composed of poorly graded sands, and from two meter depth to ten meter depth composed of well graded sands ( Figure 5). There was no underground water until the end of drilling depth (10 meter) of the studied boreholes. The sands samples at the studied cross-section were dry that means the pore water pressure    Figure 7 showed the grain size distribution curves of the studied sand samples.

Grain Size Analyses Results
The studied sand samples composed mainly of sand size ranging from 92% to 95% and trace of silt size ranging from 2% to 5% as well as trace of fine gravels ranging from 3% to 5%. The results of the grain size distribution test of the studied soils showed that the sand samples at the five studied boreholes were classified as poorly graded sands (SP) at the first two meters depth where the gradation parameters of the studied sands including coefficient of uniformity were less than 6 according to unified soil classification system (USCS). But the sands collected from two meter to ten meter depth were classified as well graded sands (SW) where the gradation parameters of the studied sands including coefficient of uniformity were more than 6 according to USCS.

Shear Wave Velocity (Vs) Results
The results pointed to that the shear wave velocities (Vs) of the studied sand samples compacted at the maximum modified proctor density were ranging from 155 to 176 m/s.

Direct Shear Box Results
The direct shear box test was carried out to determine the frictional angle (ϕ) Figure 7. Grain size distribution curves of the studies sand samples.

Standard Penetration Test (SPT) Results
Standard penetration tests (SPT) were conducted (in the field), associated with the wash mechanical drilling process, on the studied sands beds according to (Egyptian Code, Part 2, 2001) using blow weight equal to 62.5 kg and drop height equal to 76 cm, the blow numbers (N spt ) recorded each 30 cm penetration.
SPT-values were ranged from 9 to more than 45 blow number each 30 cm penetration. Generally the surface loose poorly graded sands (at the first two meters depth) have the lowest values ranging from 9 to 10. SPT-values were increased with increasing the depth and the compaction of the sands. The greatest values were ranging from 30 to 45 at about 8 to 10 meters depth and described as dense sands. Some intermediate SPT-values were ranging from 10 to 30 and described as medium dense sands (at depth ranging from 3 to 7 meters). The relationship between the SPT-values, the relative density, and the frictional angle of the soils according to the Egyptian code showed in Table 3.

Estimation of Earthquakes Factors
Earthquakes factors were estimated according to (Egyptian Code, Part 6, 2001).
There are six activity zones in Egypt arranged from the first zone to the fifth B   Table 4). The value of design ground acceleration (a g ) at seismic zone no. 1 was 0.10 g ( Table 5). The geotechnical tests results showed that the soil layer type of the study area was class D, where the number of blow each 30   Table 6. Based on the determined soil layer type (class D), the earthquakes factors including S, T B , T C , and T D were 1.80, 0.10, 0.30, and 1.20 respectively (Table 7). According to Egyptian code for vibration and dynamic load foundations, the studied project area was classified as low potential seismic. Deposits extends for tens of meters thick composed of (sand + gravel) dense or clay with heavy resistance cohesion C u shown in the table, with the increasing values of mechanical properties gradually with depth.
More than 50 More than 250 360 -800 C Deep soil deposits of non-cohesive (sand + gravel) medium to heavy or clay with resistance cohesion C u shown in the table, thickness ranges from tens to hundreds of meters.
15 -50 70 -250 180 -360 D Soil is non-cohesive (sand, gravel) loose to medium density (may be present by cohesive layers such clay, loam or the prevailing coherent soil with cohesion resistance C u shown in the table.
Less than 15 Less than 70 Less than 180 E Soil section consists of the surface layer of river sediment Vs, such C or D with variable thickness from 5 -20 m and the material underneath are strongest Vs more than 800 m/s ---

Estimation of Allowable Bearing Capacity of the Study Soils
According to the Egyptian code of shallow foundations, (in case of dry soil where pore water pressure equal to zero as in the present study area) allowable bearing capacity of the studied medium to dense sand at the designed drill depth of the shallow foundations (not less than 0.8 m depth) was ranging from 1.5 to 3 kg/cm 2 (at shallow foundation wide must not be less than 1 m). Table 8 showed the allowable bearing capacity according to (Egyptian Code, Part 3, 2001) in dry conditions for the soils.

Conclusions
The The results of the grain size analysis test of the studied soils showed that the sands samples at the five studied boreholes were classified as poorly graded Medium to Dense 1.5 -2.5 Loose 1 -1.5 Journal of Geoscience and Environment Protection sands (SP) at the first two meters depth where the gradation parameters of the studied sands including coefficient of uniformity were less than 6 according to USCS. But the sands collected from two meter to ten meter depth were classified as well graded sands (SW) where the gradation parameters of the studied sands including coefficient of uniformity were more than 6 according to USCS.
SPT-test results pointed to that the surface loose poorly graded sands (at the first two meters depth) have the lowest values ranging from 9 to 10. SPT-values were increased with increasing the depth and the compaction of the sands. The greatest values were ranging from 30 to 45 at about 8 to 10 meters depth and described as dense sands. Some intermediate SPT-values were ranging from 10 to 30 and described as medium dense sands (at depth ranging from 3 to 7 meters).
The results of the shear wave velocity tests illustrated that Vs-values were ranging from 155 to 176 m/s.
The results of direct shear box tests showed that the friction angle values of the studied sandy soils range from 32˚ to 40˚. The frictional angels of the sand at B2, B3, and B4 were 32˚, 35˚, and 40˚ respectively. The results showed also that the cohesion values (Cu) of the studied sandy soils equal to zero. According to Egyptian code for vibration and dynamic load foundations, the studied area is located in the first seismic zone (zone no. 1). The a g -value is 0.10 and the earthquakes factors including S, T B , T C , and T D were 1.80, 0.10, 0.30, and 1.20 respectively that means the studied project area was classified as low potential seismic, so that the potential for liquefaction of the soils at the study area is negligible during seismic shaking (if happened). According to the Egyptian code of shallow foundations, (in case of dry soil and the pore water pressure equal to zero as in the present study area) the allowable bearing capacity of the studied sand medium to dense at the designed drill depth of the shallow foundations (not less than 0.8 m depth) was ranging from 1.5 to 3 kg/cm 2 .

Recommendations
1) Shallow foundations either isolated footing or structural mat are recommended. According to the Egyptian code for shallow foundations, it is recommended that, the minimum drill depth of the shallow foundations must not be less than 0.8 m.
2) Compaction of the studied sands is recommended to obtain at least eighty seven percent of the maximum modified proctor density value.