Foundation Engineering CE 483 2. Site Investigations Dr Omar Hamza Copy right reserved to Dr O. Hamza

CE 483 - Foundation Engineering - 2. Site Investigation Contents Introduction Program of site investigation Planning Implementation Reporting Dr Omar Hamza CE 483 - Foundation Engineering - 2. Site Investigation

CE 483 - Foundation Engineering - 2. Site Investigation Introduction What is Site Investigation (SI)? Why Site Investigation? Objectives of Site Investigation Three Ws  three dimensions to find a space Copy right reserved to Dr O. Hamza CE 483 - Foundation Engineering - 2. Site Investigation

CE 483 - Foundation Engineering - 2. Site Investigation Introduction What is site investigation (SI)? The design of foundations of structures (such as buildings, bridges, and dams) generally requires information about: Structure Ground Structure Ground CE 483 - Foundation Engineering - 2. Site Investigation

What is site investigation (SI)? Introduction What is site investigation (SI)? Site investigation (SI) or soil exploration is the process of gathering information, within practical limits, about the stratification (layers) and engineering properties of the soils underlying the proposed construction site. The principal engineering properties of interest are the strength, deformation, and permeability characteristics. Drilling rig Structure Site Investigation Ground Soil exploration or site investigation happens to be one of the most important parts of Foundation Engineering (and at the same time the most neglected part of it). Layers Borehole

CE 483 - Foundation Engineering - 2. Site Investigation Introduction Why site investigation (SI)? Many engineering failures could have been avoided if a proper site investigation had been carried out. The site has a sinkhole risk which might have been discovered in a proper site investigation Sinkhole CE 483 - Foundation Engineering - 2. Site Investigation

CE 483 - Foundation Engineering - 2. Site Investigation Introduction Why site investigation (SI)? The success or failure of a foundation depends essentially on the reliability of the knowledge obtained from the site investigation. Sophisticated theories alone will not give a safe and sound design. CE 483 - Foundation Engineering - 2. Site Investigation

Objectives of site investigation Introduction Objectives of site investigation The knowledge about the ground of the proposed construction site is obtained by Site Investigation, and used to determine: Suitability: of site for the proposed construction? Type of design solution: e.g. type of foundation: shallow or deep. Design parameters: such as strength, compressibility, permeability & other parameters used for geotechnical design  Ground or Ground-water conditions: that would affect the design and construction? e.g. expansive soil, collapsible soil, high ground water… Geo-materials: available on site which can be re-used? Effect of changes: How will the design affect adjacent properties and the ground water? Site Investigation

Manage the geotechnical risk Introduction Objectives of site investigation Suitability: of site for the proposed construction? Type of design solution: e.g. type of foundation: shallow or deep. Design parameters: such as strength, compressibility, permeability & other parameters used for geotechnical design  Ground or Ground-water conditions: that would affect the design and construction? e.g. expansive soil, collapsible soil, high ground water… Geo-materials: available on site which can be re-used? Effect of changes: How will the design affect adjacent properties and the ground water? Manage the geotechnical risk Site Investigation CE 483 - Foundation Engineering - 2. Site Investigation

Program of site investigation Before Site Investigation The sequence of Site Investigation Dr Omar Hamza Three Ws  three dimensions to find a space CE 483 - Foundation Engineering - 2. Site Investigation

CE 483 - Foundation Engineering - 2. Site Investigation Program Before Site Investigation Site Investigation is usually carried out as part of Subsurface Exploratory program. Before conducting the Site Investigation, the program usually include: Desk Study and Site Reconnaissance. Desk Study Collect and review preliminary information about the site, and the structure to be built. Site Reconnaissance Visual inspection of the site. CE 483 - Foundation Engineering - 2. Site Investigation

CE 483 - Foundation Engineering - 2. Site Investigation Program Before Site Investigation Desk Study Collecting general information about the structure, from the architectural and structural design: Information about the Structure Type, dimensions, and use of the structure, and any special architectural considerations. the load that will be transmitted by the superstructure to the foundation system the requirements of the local building code (e.g. allowable settlement) Structure Ground CE 483 - Foundation Engineering - 2. Site Investigation

CE 483 - Foundation Engineering - 2. Site Investigation Program Before Site Investigation Desk Study Collecting general information about the ground, from already existing data such as: geological maps, seismic maps, Ariel Photography, Services records (Gas, Water, Electricity), Previous geo-environmental or geotechnical reports, … etc. at or near site. Information about the ground: the geological conditions of the ground (e.g. layers, Geological features, Ground water, Flood & Earthquake risk in the area, ..). the historical use of the site – if previously used as quarry, agricultural land, industrial unit with contamination issue, man-made fill/slope, etc. Structure Ground It is essential when conducting a desk study that as much information as possible is obtained. Work at this stage of the Investigation saves much time later and vastly improves the planning and quality of the Investigation. CE 483 - Foundation Engineering - 2. Site Investigation

CE 483 - Foundation Engineering - 2. Site Investigation Ariel Photograph taken for a site – shows a possible sinkhole CE 483 - Foundation Engineering - 2. Site Investigation

Dr Omar Hamza Site Reconnaissance Program Before Site Investigation The Site Reconnaissance is normally in the form of a walk-over survey of the site. What things do I need to look for? Dr Omar Hamza Engineer during Site Visit CE 483 - Foundation Engineering - 2. Site Investigation

Site Reconnaissance Program Before Site Investigation Important evidence to look for is: Stratification of soil: from deep cut, such as those made for the construction of nearby highway or other projects – if any. Slope: signs of slope instability include bent trees, shrinkage cracks on the ground and displaced fences or drains. Stratification of soil Signs of slope instability

Site Reconnaissance Program Before Site Investigation Important evidence to look for is: Structures: type of buildings in the area and the existence of any cracks in walls or other problems. You may need to ask local people. These indicate of ground problems such as expansive soil Indication of possible ground-related problem Tipping settlement (often without cracks) Differential settlement (with cracks) CE 483 - Foundation Engineering - 2. Site Investigation

CE 483 - Foundation Engineering - 2. Site Investigation Program Before Site Investigation Site Reconnaissance Other important evidence to look for is: Mining: The presence of previous mining is often signs of subsidence and possibly disused mine shafts. Open cast mining is indicated by diverted streams replaced or removed fence/hedge lines. Hydrogeology: Wet marshy ground, springs or seepage, ponds or streams and Wells. Topography: possible existence of drainage ditches or abandoned debris or other man-made features. Vegetation: may indicate the type of soil. Access: It is essential that access to the site can be easily obtained. Possible problems include low overhead cables and watercourses. CE 483 - Foundation Engineering - 2. Site Investigation

CE 483 - Foundation Engineering - 2. Site Investigation Program The sequence of Site Investigation Soil exploration is a requirement for the design of foundations of any project. Planning Implementation Reporting In large construction projects, 2 site investigations (SI) are carried out: Preliminary SI, followed by Detailed SI. Sequence of Site Investigation Whether investigation is preliminary or detailed, there are three important phases: planning, implementation and reporting. CE 483 - Foundation Engineering - 2. Site Investigation

CE 483 - Foundation Engineering - 2. Site Investigation Planning Planning Implementation Reporting Why planning Depth of investigation Spacing of boreholes Sequence of Site Investigation CE 483 - Foundation Engineering - 2. Site Investigation

CE 483 - Foundation Engineering - 2. Site Investigation Planning Why planning? How many borings do we need? How deep the borings should be? The more the better, but what about the cost? Borehole CE 483 - Foundation Engineering - 2. Site Investigation

CE 483 - Foundation Engineering - 2. Site Investigation Planning Why planning? Planning for site investigation is required to: Minimize cost of explorations and yet give reliable data. Decide on quantity and quality depending on type, size and importance of project and whether investigation is preliminary or detailed. Decide on minimum depth and spacing of exploration. Borehole Spacing Depth of Borehole CE 483 - Foundation Engineering - 2. Site Investigation

CE 483 - Foundation Engineering - 2. Site Investigation Planning Depth of investigation In general, depth of investigation should be such that any/all strata that are likely to experience settlement or failure due to loading. The estimated depths can be changed during the drilling operation, depending on the subsoil encoun­tered. To determine the approximate minimum depth of boring, engineers may use the following rules: Depth of Borehole CE 483 - Foundation Engineering - 2. Site Investigation

Depth of investigation Planning Depth of investigation Determination of the minimum depth of boring Determine the net increase of stress,  under a foundation with depth as shown in the Figure. Estimate the variation of the vertical effective stress, ‘0 , with depth. Determine the depth, D = D1, at which the stress increase ’ is equal to (1/10) q (q = estimated net stress on the foundation). Determine the depth, D = D2, at which /'0 = 0.05. Unless bedrock is encountered, the smaller of the two depths, D1 and D2, is the approximate minimum depth of boring required. q D 0’  ’ CE 483 - Foundation Engineering - 2. Site Investigation

CE 483 - Foundation Engineering - 2. Site Investigation Planning Depth of investigation Table shows the minimum depths of borings for buildings based on the preceding rule. Building width (m) Number of Stories Depth of Boring What do you notice about this table? CE 483 - Foundation Engineering - 2. Site Investigation

Spacing of boreholes Planning There are no strict rules for the spacing of the boreholes. The following table gives some general guidelines for borehole spacing. These spacing can be increased or decreased, depending on the subsoil condition. If various soil strata are more or less uniform and predictable, the number of boreholes can be reduced. What do you notice about this table? Type of project Spacing (m)

CE 483 - Foundation Engineering - 2. Site Investigation Implementation Planning Implementation Reporting Overview Boring Sampling Testing Sequence of Site Investigation CE 483 - Foundation Engineering - 2. Site Investigation

CE 483 - Foundation Engineering - 2. Site Investigation Implementation Overview The implementation phase of site investigation usually includes three important aspects: 1 2 3 Boring Trial pits Boreholes Sampling Soil Sampling Rock Sampling Testing In-situ tests Laboratory tests CE 483 - Foundation Engineering - 2. Site Investigation

CE 483 - Foundation Engineering - 2. Site Investigation Implementation Boring 1 2 3 Boring Trial pits Boreholes Sampling Soil Sampling Rock Sampling Testing In-situ tests Laboratory tests CE 483 - Foundation Engineering - 2. Site Investigation

CE 483 - Foundation Engineering - 2. Site Investigation Implementation Boring Trial pits Trial pits are shallow excavations - less than 6m deep. The trial pit is used extensively at the surface for block sampling and detection of services prior to borehole excavation. For safety ALL pits below a depth of 1.2m must be supported. Pick and shovel Backhoe Trial Pit 6m > depth Depth Excavation Method 0-2m By Hand 2-4m Wheeled Back Hoe 4-6m Hydraulic Excavator CE 483 - Foundation Engineering - 2. Site Investigation

CE 483 - Foundation Engineering - 2. Site Investigation Implementation Boring Boreholes Boreholes may be excavated by one of these methods: Auger Boring Wash Boring Rotary Drilling Percussion Drilling Borehole The right choice of method depends on: Ground condition: presence of hard clay, gravel, rock. Ground-water condition: presence of high ground-water table (GWT). Depth of investigation Site access CE 483 - Foundation Engineering - 2. Site Investigation

Boreholes 1. Auger Boring Implementation Boring Boreholes 1. Auger Boring This is the simplest of the methods. Hand operated or power driven augers may be used. Suitable in all soils above GWT but only in cohesive soil below GWT. Power driven augers Hand operated augers Post hole auger Helical auger

CE 483 - Foundation Engineering - 2. Site Investigation Implementation Boring Boreholes 2. Wash Boring A casing is driven with a drop hammer. A hollow drill rod with chopping bit is inserted inside the casing. Soil is loosened and removed from the borehole using water or a drilling mud jetted under pressure. Wash boring is a very convenient method for soil exploration below the ground water table provided the soil is either sand, silt or clay. The method is not suitable if the soil is mixed with gravel or boulders. CE 483 - Foundation Engineering - 2. Site Investigation

CE 483 - Foundation Engineering - 2. Site Investigation Implementation Boring Boreholes 3. Percussion Drilling In this method a heavy drilling bit is alternatively raised and dropped in such a manner that it powders the underlying materials which form a slurry with water and are removed as the boring advances. Possibly this is the only method for drilling in river deposits mixed with hard boulders of the quartzitic type. CE 483 - Foundation Engineering - 2. Site Investigation

CE 483 - Foundation Engineering - 2. Site Investigation Implementation Boring Boreholes 4. Rotary Drilling In this method a rapidly retaining drilling bit (attached to a drilling rod) cut the soil and advance the borehole. Movement transmitter When soil sample is needed the drilling rod is raised and the drilling bit is replaced by a sampler. This method is suitable for soil and rock. Rotary Head Drilling rod Drilling bit CE 483 - Foundation Engineering - 2. Site Investigation

CE 483 - Foundation Engineering - 2. Site Investigation Implementation Sampling 1 2 3 Boring Trial pits Boreholes Sampling Soil Sampling Rock Sampling Testing In-situ tests Laboratory tests CE 483 - Foundation Engineering - 2. Site Investigation

CE 483 - Foundation Engineering - 2. Site Investigation Implementation Sampling Soil sampling Samples from each type of soils are required for laboratory testing to determine the engineering properties of these soils. Soil samples are recovered carefully, stored properly to prevent any change in physical properties, and transferred to laboratory for testing. Soil Sampling equipment? Disturbed vs Undisturbed? CE 483 - Foundation Engineering - 2. Site Investigation

Soil sampling Soil Sampling equipment Implementation Sampling There is a wide range of sampling methods such as Split-spoon, Thin-walled Tube. The choice of method depends on: the requirement of disturbed or undisturbed samples Type of soil discovered at site (Gravel, Sand, Silt, Clay) Split-spoon Sampler Soil Sample advancement

Implementation Sampling Soil sampling Soil Sampling equipment

CE 483 - Foundation Engineering - 2. Site Investigation Implementation Sampling Soil sampling Disturbed vs Undisturbed Two types of soil samples can be obtained during sampling: disturbed and undisturbed. The most important engineering properties required for foundation design are strength, compressibility, and permeability. These tests require undisturbed samples. Disturbed samples can be used for determining other properties such as Moisture content, Classification & Grain size analysis, Specific Gravity, and Plasticity Limits. CE 483 - Foundation Engineering - 2. Site Investigation

CE 483 - Foundation Engineering - 2. Site Investigation Implementation Sampling Soil sampling Disturbed vs Undisturbed It is nearly impossible to obtain a truly undisturbed sample of soil. The quality of an "undisturbed" sample varies widely between soil laboratories. So how is disturbance evaluated? Quality of samples is evaluated by calculating Area Ration AR: Outer Diameter Inner Dia. Sampling tube soil The thicker the wall of the sampling tube, the greater the disturbance. Good quality samples AR<10% . CE 483 - Foundation Engineering - 2. Site Investigation

CE 483 - Foundation Engineering - 2. Site Investigation Implementation Sampling Soil sampling Disturbed vs Undisturbed Samples collected in Split-spoon Sampler is usually classified as “disturbed”. What is the Area Ration? Area Ration AR = ----------------- = CE 483 - Foundation Engineering - 2. Site Investigation

CE 483 - Foundation Engineering - 2. Site Investigation Implementation Sampling Rock Sampling (Coring) Rock samples are called “rock cores”, and they are necessary if the soundness of the rock is to be established. Core drilling equipment? Core recovery parameters? CE 483 - Foundation Engineering - 2. Site Investigation

Rock Sampling (Coring) Implementation Sampling Rock Sampling (Coring) Core drilling equipment Drill rod Coring is done with either tungsten carbide or diamond core bits. Rock sampler is called “core barrel” which usually has a single tube. Double or triple tube core barrel is used when sampling of weathered or fractured rock. Inner barrel Core barrel Outer barrel Rock Rock Rock Rock Rock core Coring bit Diamond Drill Bit (a) (b) Core barrel: (a) Single-tube; (b) double-tube

CE 483 - Foundation Engineering - 2. Site Investigation Implementation Sampling Rock Sampling (Coring) Core drilling equipment Cores tend to break up inside the drill barrel, especially if the rock is soft or fissured. Core recovery parameters are used to describe the quality of core. Length of pieces of core are used to determine: Core Recovery Ratio (Rr) Rock Quality Designation (RQD) Rock cores CE 483 - Foundation Engineering - 2. Site Investigation

Rock Sampling (Coring) Implementation Sampling Rock Sampling (Coring) Core drilling equipment Assuming the following pieces for a given core run: (Core run) Rr Recovery Ratio, Rr Core recovery (lengths of intact pieces of core) Rock Quality Designation, RQD 10 S L i = 100% ( L i ≥ 10 cm ) (Core run) L

CE 483 - Foundation Engineering - 2. Site Investigation Implementation Sampling Rock Sampling (Coring) Core recovery parameters So Rock Quality Designation (RQD) is the percentage of rock cores that have length ≥ 10 cm over the total drill length (core run). RQD may indicate the degree of jointing or fracture in a rock mass. e.g. High-quality rock has an RQD of more than 75%. RQD is used in rock mass classification systems and usually used in estimating support of rock tunnels. CE 483 - Foundation Engineering - 2. Site Investigation

CE 483 - Foundation Engineering - 2. Site Investigation Implementation Sampling Rock Sampling (Coring) Core recovery parameters Class Example Work out Rr and RQD for the following core recovery (intact pieces), assuming the core run (advance) is 150 cm. What is the rock mass quality based on RQD? CE 483 - Foundation Engineering - 2. Site Investigation

CE 483 - Foundation Engineering - 2. Site Investigation Implementation Sampling Rock Sampling (Coring) Core recovery parameters Solution: Total core recovery L = 125 cm Core recovery ratio: Rr = 125/150 = 83% On modified basis (for pieces ≥ 10cm), 95 cm are counted, thus: RQD = 95/150 = 63 % RQD = 50% - 75%  Rock mass quality is “Fair” ? S L i 100% = L L S L i = ? ? CE 483 - Foundation Engineering - 2. Site Investigation

CE 483 - Foundation Engineering - 2. Site Investigation Implementation Testing 1 2 3 Boring Trial pits Boreholes Sampling Soil Sampling Rock Sampling Testing In-situ tests Laboratory tests CE 483 - Foundation Engineering - 2. Site Investigation

In-situ tests Introduction Plate Load Test (PLT) Implementation Testing In-situ tests Introduction Groundwater measurements Standard Penetration Test (SPT) Cone Penetration Test (CPT) Plate Load Test (PLT) Pressure-meter Test (PMT) Flat Dilatometer Test (DMT) Vane shear test (VST) PLT Piezometer In Borehole

CE 483 - Foundation Engineering - 2. Site Investigation Implementation Testing : In-situ tests Introduction Definition: In-situ tests are carried out in the field with intrusive testing equipment. If non-intrusive method is required, then it is better to use geophysical methods which use geophysical waves – i.e. without excavating the ground. Advantage of in-situ testing (against lab testing) It avoids the problems of sample recovery and disturbance some in-situ tests are easier to conduct than lab tests In-situ tests can offer more detailed site coverage than lab testing. Testing standards American Society for Testing and Materials (ASTM) British Standard (BS) CE 483 - Foundation Engineering - 2. Site Investigation

CE 483 - Foundation Engineering - 2. Site Investigation Implementation Testing : In-situ tests Groundwater measurements Why Groundwater: Groundwater conditions are fundamental factors in almost all geotechnical analyses and design studies. Types of Groundwater measurements: Determination of groundwater levels (GWT) and pressures. Borehole instrumented with Piezometer is used for this purpose. Measurement of the permeability of the subsurface materials, particularly if seepage analysis is required. The test called Pumping test. Ground water level Standpipe Piezometer CE 483 - Foundation Engineering - 2. Site Investigation

CE 483 - Foundation Engineering - 2. Site Investigation Implementation Testing : In-situ tests Standard Penetration Test (SPT) Definition This empirical test consists of driving a split- spoon sampler, with an outside diameter of 50 mm, into the soil at the base of a borehole. Drivage is accomplished by a trip hammer, weighing 65 kg, falling freely through a distance of 760 mm onto the drive head, which is fitted at the top of the rods. The split-spoon is driven three times for a distance of 152.4 mm (6 in) into the soil at the bottom of the borehole. The number of blows required to drive (only) the last two 152.4 mm are recorded. The blow count is referred to as the SPT-N. Falling Hammer 760 mm Drive head Slit spoon 152.4 mm (6 in) x 3 times The first one does not count CE 483 - Foundation Engineering - 2. Site Investigation

CE 483 - Foundation Engineering - 2. Site Investigation Implementation Testing : In-situ tests Standard Penetration Test (SPT) Advantage Relatively quick, simple, reasonably cheap, and suitable for most soils. good correlation between SPT-N and soil properties. provides a representative soil sample for further testing. Disadvantage SPT does not typically provide continuous data Limited applicability to soil containing cobbles and boulders. Samples obtained from the SPT are disturbed. SPT N blow require correction CE 483 - Foundation Engineering - 2. Site Investigation

Standard Penetration Test (SPT) Implementation Testing : In-situ tests Standard Penetration Test (SPT) Corrections for energy and equipment Corrections are normally applied to the SPT blow count (N) to account for: Energy loss: during the test (about only 60% of energy remains) Equipment differences: hammer, sampler, borehole diameter, rod The following equation is used to compensate for these factors: (usually 0.50-0.80) (1.0-1.15) (0.8-1.0) 60% (0.75-1.0) Usually this correction is made by the Site Investigation operator.

Standard Penetration Test (SPT) Implementation Testing : In-situ tests Standard Penetration Test (SPT) Corrections for overburden pressure In granular soil (sand, gravel) the SPT blows are influenced by the effective overburden pressure at the test depth: CN =  overburden pressure correction factor Many equations have been suggested for CN – see Page 86, (Das’s text book). For example:

Standard Penetration Test (SPT) Implementation Testing : In-situ tests Standard Penetration Test (SPT) Correlation between N and friction angle There are many equations suggested. The figure shows the correlation with the angle of shearing resistance of sand (according to Pecks, 1974). Corrected SPT N blow Angle of shearing resistance f’ (degree)

Standard Penetration Test (SPT) Implementation Testing : In-situ tests Standard Penetration Test (SPT) Class example The following are the recorded numbers of SPT blows required for spoon penetration of three 152.4cm (6 in) in a sand deposit: Depth from ground surface (m) 1.5 3 4.5 6 7.5 SPT blows (blow/ 6 in) 3, 4, 5 7, 9, 10 7, 12, 11 8, 13, 14 10, 14, 15 Note. Assume the above SPT blows are corrected for energy and equipment. The ground water table (GWT) is located at a depth of 4.5m. The wet unit weight of sand above GWT is 18 kN/m3, and the saturated unit weight of sand below GWT is 19.81 kN/m3. Draw a sketch of the foundation showing the given details of the soil. Determine the standard penetration number (SPT-N) at each depth. What is the corrected (SPT-N) value? (use Seed’s equation). Determine the friction angle at depth 4m below the footing. (Use Peck’s Equation or Chart).

Standard Penetration Test (SPT) Implementation Testing : In-situ tests Standard Penetration Test (SPT) Solution Z, m SPT blow N60 s0’ (kPa) CN N f’ 1.5 3, 4, 5 4+5=9 1.5x18 =27 0.27 1.7 15.3 35o 3 7, 9, 10 9+10=19 54 0.54 4.5 7, 12, 11 23 6 8, 13, 14 ? 7.5 10, 14, 15 2 g =18 kN/m3 4 gsat=19.8 kN/m3 Only the last 2 sets of blows count Z Corrected

CE 483 - Foundation Engineering - 2. Site Investigation Implementation Testing : In-situ tests Standard Penetration Test (SPT) Correlation between N and untrained shear strength The corrected SPT N blow can be approximately correlated to many important engineering properties of soil such as shear strength & compressibility. This equation shows the correlation with untrained shear strength Su (or Cu) of clay. (also with OCR = Over Consolidation Ratio). In Clay CE 483 - Foundation Engineering - 2. Site Investigation

CE 483 - Foundation Engineering - 2. Site Investigation Implementation Testing : In-situ tests Standard Penetration Test (SPT) Correlation between N and untrained shear strength The table shows the correlation corrected SPT-N with untrained shear strength Su (or Cu) of clay (according to Terzaghi et al. 1996) CE 483 - Foundation Engineering - 2. Site Investigation

CE 483 - Foundation Engineering - 2. Site Investigation Implementation Testing : In-situ tests Standard Penetration Test (SPT) Class Example the Figure shown below CE 483 - Foundation Engineering - 2. Site Investigation

Standard Penetration Test (SPT) Implementation Testing : In-situ tests Standard Penetration Test (SPT) Solution Z, m N60 s0’ (kPa) Cu (kPa) s0’ (MPa) OCR 3 5 1.5x16.5+ 1.5x(19-9.81) = 38.5 100x0.29 x50.72 =92.3 38.5/1000= 0.0385 0.193x(5/ 0.038)0.689 = 5.5 4.5 8 38.5+1.5x(16.5-9.81) = 48.5 129.6 0.0485 6 7.5 9 10 Cu -av = OCRav =

CE 483 - Foundation Engineering - 2. Site Investigation Implementation Testing : In-situ tests Standard Penetration Test (SPT) Correlation between N and Relative Density Dr correlation between N60 and Relative Density of Granular Soil General For Clean sand only Copy right reserved to Dr O. Hamza CE 483 - Foundation Engineering - 2. Site Investigation

CE 483 - Foundation Engineering - 2. Site Investigation Implementation Testing : In-situ tests Standard Penetration Test (SPT) Correlation between N and Relative Density Dr Very loose Loose Medium Dense CE 483 - Foundation Engineering - 2. Site Investigation

Standard Penetration Test (SPT) Implementation Testing : In-situ tests Standard Penetration Test (SPT) Correlation between Modulus of Elasticity and Standard Penetration Number The modulus of elasticity of granular soils (Es) is important parameter in estimation the elastic settlement of foundation. An approximate estimation for Es was given by Kulhawy and Mayne (1990) as:

CE 483 - Foundation Engineering - 2. Site Investigation Implementation Testing : In-situ tests Cone Penetration Test (CPT) Definition called also "Dutch cone test“ or “Static Penetration test”. The test method consists of pushing an instrumented cone, with the tip facing down, into the ground at a slow controlled rate. Cone: 60 degree apex cone, Dia = 36 mm. Hydraulic push at rate 20 mm/s Cone Rod (36 mm dia.) Measures Cone or Tip resistance (qc) or (qt) Sleeve friction (fs) Water Pore pressure (ub) Friction Ratio, Fr = qc fs fs Cone Other variables e.g. Shear wave velocity (vs) qc or qt CE 483 - Foundation Engineering - 2. Site Investigation

CE 483 - Foundation Engineering - 2. Site Investigation Implementation Testing : In-situ tests Cone Penetration Test (CPT) Tip resistance, qc Sleeve friction, fs Pore Pressure, u Friction Ratio , Fr Applications: Soil profile (stratigraphy): soil type identification Estimation of geotechnical parameters (strength, compressibility, permeability) Evaluation of groundwater conditions (pore pressure) Geo-environmental: distribution and composition of contaminants Clay Clay & Silt Clay & Sand Silty Clay CE 483 - Foundation Engineering - 2. Site Investigation Sample data

Cone Penetration Test (CPT) Implementation Testing : In-situ tests Cone Penetration Test (CPT) Soil Identification: Point resistance qc High in granular soil Low in cohesive soil Friction Ratio Fr Low in granular soil High in cohesive soil However, the cone/tip (qc) and sleeve (fs) resistance increase with increasing overburden stress s0 for accurate identification, normalization of qc & fs by overburden stress is required. Classification Chart (Robertson et al., 1983)

CE 483 - Foundation Engineering - 2. Site Investigation Implementation Testing : In-situ tests Cone Penetration Test (CPT) Advantages: Borehole is not necessary Almost continuous data (reading every 10mm) Elimination of operator error (automated) Reliable, repeatable test results Disadvantages: Inability to penetrate through gravels and cobbles Newer technology = less populated database than SPT Lack of sampling CE 483 - Foundation Engineering - 2. Site Investigation

CE 483 - Foundation Engineering - 2. Site Investigation Implementation Testing : In-situ tests Cone Penetration Test (CPT) Correlation with shear strength In Sand: the drained friction angle (Ricceri et all’s. 2002) In Clay: undrained shear strength cu where: qc = the cone (tip) (point) resistance s’0 & s0 = effective and total overburden pressure, respectively NK = Bearing factor depends on type of cone (varies from 11-20) OCR = Over Consolidation Ratio CE 483 - Foundation Engineering - 2. Site Investigation

Cone Penetration Test (CPT) Implementation Testing : In-situ tests Cone Penetration Test (CPT) Class example: Correlation with shear strength Use equation proposed by Ricceri et all’s. 2002.

Cone Penetration Test (CPT) Implementation Testing : In-situ tests Cone Penetration Test (CPT) Solution: Depth, m qc (MPa) s0’ (kPa) qc /s0’ f’ (Rad) f’ (deg) 1.5 2.06 1.5 x 16 =24 2060 / 24 = 85.8 0.69 0.69x180/p=40o 3 4.23 48 88.1 4.5 6.01 6 8.18 7.5 9.97 9.0 12.42 ATAN Returns the arctangent, or inverse tangent, of a number. f’av = f’av = Sf’ / 6 Note. tan -1 is inverse tangent, the angle returned is in Radian.

Plate Load Test (PLT) Implementation : In-situ tests Testing Plate load test is a field test to determine the ultimate bearing capacity of soil. The test essentially consists in loading a rigid steel plate at the foundation level and determining the settlement corresponding to each load increments. The ultimate bearing capacity is then taken as the load at which the plate starts sinking at a rapid rate.

CE 483 - Foundation Engineering - 2. Site Investigation Implementation Testing Laboratory tests CE 483 - Foundation Engineering - 2. Site Investigation

CE 483 - Foundation Engineering - 2. Site Investigation Implementation Testing Laboratory tests Basic physical properties tests (Moisture content, Specific gravity, Soil Indexes, ..) Particle size test (sieving, Sedimentation) Direct shear box test Unconfined compression test Triaxial test Consolidation test Permeability test Other lab tests: Chemical test (pH, contamination,..) CE 483 - Foundation Engineering - 2. Site Investigation

CE 483 - Foundation Engineering - 2. Site Investigation Reporting Planning Implementation Reporting Preparation of Borehole Site Investigation Report Sequence of Site Investigation CE 483 - Foundation Engineering - 2. Site Investigation

CE 483 - Foundation Engineering - 2. Site Investigation Reporting Preparation of Boring Logs Initial information: Name and address of the drilling company, Driller’s name, Job description and reference number, boring information (number, type, and location of, and date of boring). Example of a typical boring log CE 483 - Foundation Engineering - 2. Site Investigation

CE 483 - Foundation Engineering - 2. Site Investigation Reporting Preparation of Boring Logs Subsurface stratification: which can be obtained by visual observation of the soil brought out by auger, split-spoon sampler, and thin-walled Shelby tube sampler. Groundwater: Elevation of water table and date observed, use of casing and mud losses, and so on CE 483 - Foundation Engineering - 2. Site Investigation

CE 483 - Foundation Engineering - 2. Site Investigation Reporting Preparation of Boring Logs In-situ tests: Standard penetration resistance and the depth of SPT Samples: Number, type, and depth of soil sample collected; in case of rock coring, type of core barrel used and, for each run, the actual length of coring, length of core recovery, and RQD. CE 483 - Foundation Engineering - 2. Site Investigation

Preparation of Boring Logs Reporting Preparation of Boring Logs Class example The following borehole is part of a site investigation (SI) carried out over a proposed location of a bridge. Assess the subsoil conditions and ground-water conditions based on the borehole data. In particular write about: Soil layers: types, description, depth… Soil properties: shear strength properties -based on SPT. Ground water depth Copy right reserved to Dr O. Hamza

CE 483 - Foundation Engineering - 2. Site Investigation

CE 483 - Foundation Engineering - 2. Site Investigation Reporting Site Investigation Report Site Investigation When: After the completion of all of the field and laboratory work, a site investigation report is prepared. Why: for the use of the design office and for reference during future construction work. The report is also called soil exploration report or Geotechnical Factual report. What should be included in the site investigation report? CE 483 - Foundation Engineering - 2. Site Investigation

Site Investigation Report Reporting Site Investigation Report The report should contain descriptions of the followings: Purpose & Scope of the investigation Site & Structure: site location, existing structures, drainage conditions, vegetation,… and information about the structure. Factual Details of field exploration: boreholes, samples, and testing. For each type, quantities, method, tools should be presented. Geological setting of the site (variation of depth and thickness of layers as interpreted from the borings) Subsoil and water-table conditions, (soil parameters as interpreted from the testing results). Design analysis & recommendations: type of foundation, allowable bearing pressure, settlement estimation, and any special construction procedure; alternatives design solution. Conclusions and limitations of the investigations Usually given in another report (Geotechnical Design Report) CE 483 - Foundation Engineering - 2. Site Investigation

CE 483 - Foundation Engineering - 2. Site Investigation Reporting Site Investigation Report The following graphical presentations must be attached to the report: General map showing site location A plan view of the location of the borings with respect to the proposed structures and those nearby Boring logs (including in-situ tests results and samples) Laboratory test results Other graphical presentations (geotechnical cross section based on the boring logs, photos of the field work and soil samples,…) CE 483 - Foundation Engineering - 2. Site Investigation

Site Investigation Report Reporting Site Investigation Report Geotechnical cross section based on the boring logs