Site investigation

1. Site investigation
‫التربة‬ ‫تحريات‬
Part (1)

2. Site investigation can be defined as the process of investigating a proposed
construction site for the purpose of collecting, assessing and reporting information
and data regarding the site. This collected information is then used to generate a
report detailing the physical ground conditions, topography, soil and rock properties
and hazards that may present at the site. The different stages of site investigation are
reconnaissance, data and map study, in-depth or intrusive site investigation, and
laboratory testing.
‫تحري‬
‫التربة‬
:
‫ي‬
‫مكن‬
‫تعريفها‬
‫على‬
‫أنها‬
‫عملية‬
‫التحقيق‬
‫في‬
‫موقع‬
‫بناء‬
‫مقترح‬
‫لغرض‬
‫جمع‬
‫المعلومات‬
‫والبيانات‬
‫المتعلقة‬
‫بالموقع‬
‫وتقييمها‬
‫واإلبالغ‬
‫عنها‬
،
‫ثم‬
‫ستخدم‬ُ‫ت‬
‫هذه‬
‫المعلومات‬
‫المجمعة‬
‫إلنشاء‬
‫تقرير‬
‫يوضح‬
‫بالتفصيل‬
‫ظروف‬
‫األرض‬
‫المادي‬
‫ة‬
‫والتضاريس‬
‫وخصائص‬
‫التربة‬
‫والصخور‬
‫والمخاطر‬
‫التي‬
‫قد‬
‫تكون‬
‫موجودة‬
‫في‬
‫الموقع‬
:
‫المراحل‬
‫المختلفة‬
‫لفحص‬
‫الموقع‬
‫هي‬
‫االستطالع‬
،
‫ودراسة‬
‫البيانات‬
‫والخريطة‬
،
‫والتحقيق‬
‫المتعمق‬
‫أو‬
‫المتداخل‬
‫في‬
‫الموقع‬
،
‫وال‬
‫فحص‬
‫المختبري‬
.

3. Purpose of Soil Exploration:
1.The purpose of site exploration is to get detailed information abouorder of
occurrences and extent of soil and rock strata.
2.Nature and engineering properties of the soil and rock formation.
3.Location of groundwater and its variation.
Planning of Soil Exploration:
Soil exploration planning depends on:
1.Nature of subsoil
2.Type of structure
3.Importance of structure

4. Steps of site investigation
1- boring (
‫الحفر‬
)
2- sampling (
‫النماذج‬
)
3- Testing (
‫الفحص‬
)
4- Reporting (
‫التقرير‬
)

5. 1- Boring methods: are widely used for subsurface investigations to collect
samples, in almost all types of soil, for visual inspection or laboratory testing. There
are several boring techniques like auger boring (
‫الحفر‬
‫بالمثقاب‬
) , rotary drilling (
‫الحفار‬
‫الدوراني‬
) , wash boring (
‫الحفر‬
‫بالغسل‬
) , percussion drilling (
‫الحفر‬
‫بالدق‬
) , auger drilling ‫المثقاب‬
‫اليدوي‬, and test pits (
‫حفر‬
‫االختبار‬
) that are employed to collect disturbed (
‫نماذج‬
‫مخلخلة‬
) and
undisturbed samples (
‫نماذج‬
‫غير‬
‫مخلخلة‬
) of soils
These boring methods are selected based 1-on the soil types, 2- the efficiency of
boring technique, 3- types of soil sample (disturbed or undisturbed), and 4- the
availability of facility and accuracy by which soil and groundwater variations can be
determined.
These techniques are used to take soil samples at a certain practical depth, for example, auger
boring collects undisturbed soil sample at a depth of 35m, whereas, the sampling depths for
percussion drilling, wash boring, and rotary drilling are around 70m.

6. Boring Methods for Soil Sampling:
1. Auger Boring ‫اليدوي‬ ‫المثقاب‬
It is a simple and cost-effective boring technique which can
be used for almost all types of soil apart from gravelly soil
and rocks. This technique encounters difficulty in gravelly
soil and special drilling bits are needed for rocks.
Auger boring is used to collect undisturbed soil specimen. It
collects the soil sample from a maximum practical depth of
nearly 35m based on the available time and equipment type.

7. 2. Rotary Drilling ‫الدوراني‬ ‫الحفار‬
Rotary drilling method of boring is
suitable for all types of soil including
rocks. It is used to take disturbed as well
as undisturbed soil sample. So, it is
specifically applicable for stiff soil layers.
The practical depth of sampling is around
70m and greater depth based on the type
of utilized equipment.
Generally, thin-walled tube samplers and
various piston (
‫المكبس‬
) samplers are used
to collect undisturbed soil specimen. The
diameter of the undisturbed soil sample
is around 100 mm and ranges from
150mm to 200mm for rocks.

8. 3. Wash Boring ‫بالغسل‬ ‫الحفر‬
Wash boring method is used to collect
disturbed and undisturbed samples in almost
all types of soils except rocks. In this technique,
portable (
‫قابل‬
‫للنقل‬
‫او‬
‫الحمل‬
) , cheap, and limited
equipment is used which is an advantage of
wash boring. Similar to rotary drilling, thin-
walled tube samplers and piston samplers are
used to recover undisturbed soil samples with
minimum 50 mm diameter and maximum 100
mm diameter.

9. 4. Percussion Drilling ‫بالدق‬ ‫الحفر‬
It is used for all types of soils and rocks
including stiff soils and rocks. Percussion
drilling is used to take disturbed and
undisturbed specimen but the quality of
undisturbed samples is not that good
because of the heavy blows of the chisel
(
‫الدقاق‬
‫او‬
‫االزميل‬
) .
Similar to rotary drilling and wash boring,
the soil specimen can be taken from a
depth of 70m and more based on the
utilized equipment. The diameter of
disturbed soil samples is about 100 mm
and greater, and obtaining smaller
diameter samples would be uneconomical.

10. 5. Test Pits and Open Cut ‫المفتوح‬ ‫والقطع‬ ‫الحفر‬ ‫اختبار‬
This type of soil sample collection technique is used for all kind of soils. It is used to take out disturbed
and undisturbed soil samples from the earth with a maximum practical depth of 6m using power
equipment. Samples are subsequently hand trimmed.
TYPE OF SAMPLING
1- Undisturbed samples (
‫غيرمخلخلة‬ ‫نماذج‬
)
2- Disturbed samples (
‫مخلخلة‬ ‫نماذج‬
)

13. SOIL SAMPLING
The disturbed samples will be taken at certain intervals to the borehole depth
termination and at the change of strata in borehole under application of various
sampling methods and respective technical standards. Disturbed samples can be
derived from selected recovered cores of standard penetration tests (SPT).
Undisturbed sampling using the open-tube sample as thin-walled or thick-walled tube
samplers can be applied depending on the encountered soil conditions whereas the
thick-walled tube sampler is applied for stiff and dense soils and for soils containing
coarse particles. For soil types that are difficult to sample, sample-retaining or closure
devices are necessary.
Undisturbed sampling using the piston sampler can be applied in low-strength fine
soils such as silt and clay, including sensitive clays. It can be used either in boreholes
or be pushed directly into the soil

15. Rock Sampling
In sampling by rotary core drilling, a tube system fitted with a bit at its lower end is
rotated and fed into the rock mass by the drill rig via the drill string. This action
produces a core sample within the tube system. A flushing medium is normally used.
The sampling tool, i.e. the core barrel, can be a single tube, double tube or triple
tube with a borehole diameter of 70 mm to 200 mm. The rock coring should be
executed minimum 5m into the rock.
For detailed guidance on the suitability of various core drilling and sampling
techniques in different types of soil and rock, our geotechnical expert will provide
professional advice.
Samples can be obtained by this method as cores/cuttings. The single-tube core
barrel only allows core recovery in consolidated formations, whereas double-tube
and triple-tube core barrels can be used in all rock formations.
The quality of the rock recovery achieved is determined by applying the following
parameters as rock quality designation (RQD), total core recovery (TCR) and solid
core recovery (SCR) ratios that have to be recorded and reported for each core run.

17. Site Investigation
part 2

18. 1- FIELD TESTING
1- Standard Penetration Test (SPT) ‫القياسي‬ ‫االختراق‬ ‫فحص‬
2- Field Vane Shear Test (VST) ‫المروحة‬ ‫فحص‬
3- Cone Penetration Test (CPT) ‫المخروط‬ ‫اختراق‬ ‫فحص‬
TESTING

19. 1- Standard Penetration Test (SPT) ‫القياسي‬ ‫االختراق‬ ‫فحص‬
Standard Penetration Tests (SPT) shall be performed in boreholes in order to estimate
consistency, relative density, and strength-deformation parameters of soils. In addition
to this soil samples
obtained from SPT testing are used for classification purposes. SPT testing can also
be carried out in weak weathered rock. The SPT testing shall be performed at certain
numbers and respective intervals (it is common to apply an interval of 1.5m/test) to the
borehole depth termination for all boreholes. The number of blows required to 15cm of
penetration or fraction thereof is to be recorded. The first 15cm is to be considered as a
seating drive. The number of blows required for the second and the third 15cm
penetration is termed as “standard penetration resistance” or the raw “N value”.

21. 2- Field Vane Shear Test (VST) ‫المروحة‬ ‫قص‬ ‫فحص‬
Vane Shear Test (VST) is an in-place shear test in which a rod with thin radial vanes
at the end is forced into the soil and the resistance to rotation of the rod is
determined. VST addresses testing on land and for testing in drill holes or by self
drilling or continuous push methods from the ground surface. VST provides an
indication of in-situ undrained shear strength of fine- grained clays and silts.
Knowledge of the nature of the soil in which each vane test is to be made is
necessary for assessment of the applicability and interpretation of the test. The test
is not applicable for sandy soils which may allow drainage during the test. The test is
routinely performed in conjunction with other field and laboratory tests.

23. 3- Cone Penetration Test (CPT)‫المخروط‬ ‫اختراق‬ ‫فحص‬
Cone penetration test (CPT) can be performed to evaluate effectively the site
characterization. It is a valuable method of assessing the subsurface stratigraphy
associated with soft materials, discontinuous lenses, organic soil, potentially
liquefiable materials (silt, sands and granule gravel), generally excluding bedrock,
very dense granular fill and strata containing boulders. CPT is performed using a
cylindrical penetrometer with a cone penetrating the ground at a constant rate.
During the penetration, the forces on the cone and the friction sleeve are
measured. CPT and the measured data can be used to evaluate soil conditions
and parameters.

25. 2- Laboratory Testing
1- Moisture content ‫الرطوبي‬ ‫المحتوى‬
2- Unit weight ‫الوزن‬ ‫وحدة‬
3- Atterberg limits‫اتربرك‬ ‫حدود‬
a- plastic limit ‫اللدونة‬ ‫حد‬
b- liquid limit ‫السيولة‬ ‫حد‬
c- Plasticity Index ‫اللدونة‬ ‫دليل‬
4- Sieve Analysis ‫المنخلي‬ ‫التحليل‬
1- Index property tests

26. 2- Engineering properties tests
1- Unconfined compression strength ‫محصور‬ ‫الغير‬ ‫االنضغاط‬ ‫فحص‬
2- Consolidation test ‫االنظمام‬ ‫فحص‬
3- Triaxial compression tests ‫الثالثي‬ ‫االنضغاط‬ ‫فحص‬
3- Rock Strength Properties Tests
1- Point load test ‫النقطة‬ ‫تحميل‬ ‫فحص‬
2- Uniaxial compression strength test ‫المحور‬ ‫احادي‬ ‫االنضغاط‬ ‫فحص‬

27. 3- Chemical Analysis of Groundwater
1- PH value ‫الحامضية‬ ‫قيمة‬
2- sulphate content ‫الكبريتات‬ ‫محتوى‬
3- chloride content tests ‫الكلوريد‬ ‫محتوى‬ ‫فحص‬
4- REPORT
The detailed Report will be provided and prepared tailor-made for each project
according to the respective project scope of service. The following table of content is
a standard table of content that will be adjusted according to the project scope of
service:

28. 1- Project description ‫الموقع‬ ‫وصف‬
2- Description of the works performed with Respect to the geotechnical investigation
programmed ‫الموقعي‬ ‫التحري‬ ‫برنامج‬ ‫مراعاة‬ ‫مع‬ ‫المنجزة‬ ‫االعمال‬ ‫وصف‬
4- Technical standards ‫التقنية‬ ‫المعايير‬
5- Site conditions ‫الموقع‬ ‫شروط‬
Conclusions and Recommendation
1- Geotechnical soil conditions of the project site
2- Recommendation for building foundation methods, soil improvement methods …
(acc. to the project scope)

29. Appendices
1- Summary of laboratory testing results on index and engineering properties
2- Bore logs and standard penetration test results
3- Vane shear test results
4- Results of laboratory testing
5- Work progress reports and photo documentation
6- Daily site record
7- Drawings