Planning Exploration & Testing Program Groundwater observations GW condition is an important factor to observe for design and construction e.g. deep excavation ,tunneling, deep foundation, slope stability analysis & etc.: Groundwater level must be determined during site investigation works. Measure at time of drilling and later (24 hrs., 1 week, etc.). Can be accomplished by make observations in borehole & existing. Or, install a piezometer. Monitor Wells & Sampling. Permeability Tests. 33
Geomaple Common Geotechnical Field Procedures and Tests.
Geomaple - Grain analysis - Atterberg limits - Shrinkage limit (SL) - Specific Gravity (Gs) - Permeability - Consolidation, Swelling & collapsibility - Direct shear - Uni-axial - Tri-axial - Compaction & CBR - Moisture content - Unit weight
Geomaple Common Procedures and Laboratory Tests for Soils.
Soil constitutive model (Parameters) General properties Density ( ρ ) Permeability 37 Advanced Soil Mechanics; Braja M. Das; Third edition; 2008
Soil constitutive model (Parameters) Poisson’s (ʋ) 38 Correlations of Soil and Rock Properties in Geotechnical Engineering; Jay Ameratunga, Nagaratnam Sivakugan, Braja M. Das; 2016
Soil constitutive model (Parameters) Modulus of Elasticity (E) 1.Correlation of N (SPT) with Modulus of Elasticity (E) for Sandy Soils 39 Correlations of Soil and Rock Properties in Geotechnical Engineering; Jay Ameratunga, Nagaratnam Sivakugan, Braja M. Das; 2016
Soil constitutive model (Parameters) Modulus of Elasticity (E) 1.Correlation of N (SPT) with Modulus of Elasticity (E) for Sandy Soils Modulus of elasticity for Granular soils 2. Plate Load Test (PLT) Modulus of elasticity for Cohesive soils I P 1 2 E D S 3. Pressuremeter Test E ( 1 )( 1 2 ) p E s ( 1 ) Pressuremeter modulus (E p ) 40 Correlations of Soil and Rock Properties in Geotechnical Engineering; Jay Ameratunga, Nagaratnam Sivakugan, Braja M. Das; 2016
Soil constitutive model (Parameters) Cohesion and Friction angle - Direct shear - Uniaxial - Triaxial - Vane Shear Test - In Situ Shear Test - Edge Plate Load Test (EPLT) 41 Correlations of Soil and Rock Properties in Geotechnical Engineering; Jay Ameratunga, Nagaratnam Sivakugan, Braja M. Das; 2016
Geomaple Chemical analysis of Soil samples and groundwater chemistry Some of the chemical materials in the soils can cause damages on the buried concrete structures in sub-surface layers, which lead to serious problems on underground structures such as tunnels and sub-way stations. • pH • pH • Cl - (ppm) • CL - % Chemical Chemical analysis -2 % • E c (µmhos/cm) • SO 3 materials of groundwater -2 (ppm) • So 4 • CaSO 4 ,2H 2 O % • T.D.S (ppm) • Organic Material %
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Geomaple • Foundation design Geotechnical • Shoring • Slope stability • Dewatering • Water balance Hydrogeology • Water proofing • Drainage • Storm water management • Excavation Environmental • Damping • Synthetic cleaning
Geotechnical properties GBR(Geotechnical Base Report) data presentation and report The interpretation and analysis were done based on the method used for analysis. Bore log information (drilling & sampling depths & methods, field test data, drilling notes, soil appearance, stratification and etc.) Content of report (introduction, site description, site geology, soil conditions, discussion, appendices and etc.) 45
GBR(Geotechnical Base Report) data presentation and report Introduction – brief summary of proposed works, investigation conducted, site location, timescale of the work, key personnel. Site Description – Topography, main surface features, detail access, site history, site maps, pre-existing works / underground openings. Site Geology – Overall geology, specific area geology, main soil and rock formation/structures. Soil Conditions – detailed account of the conditions encountered (in relation to the proposed works), description of all strata, results of laboratory and in situ tests, detail of groundwater conditions. Discussion – Comments on validity and reliability of the information presented, further work (if required). Definition of appropriate design parameters and methods of both design and construction (interpretative report) Appendices – borehole logs, laboratory test results, in situ tests, geophysical survey records, references, literature extracts 46 GEOTECHNICAL ENGINEERING Site Investigation, Dr. Amizatulhani Abdullah
Step by Step Design Empirical design 1- Approximate Predictive Design 2- Experimental Predictive Design 3- Neural Network Limit Equilibrium method Stress-Strain Analyses 1- FEM (Finite Element Method) 2- FDM (Finite Deference Method) 3- BEM (Boundary Element Method) 47
Limit Equilibrium method Input Output Geometry Safety Factor Surcharge Condition Element Force Soil Parameters Seepage Limit Equilibrium Solver Water Condition … 48
Stress – Strain Analyze Input Output Geometry Stress Distribution Constitutive Model parameters Strain Distribution Element Parameters Crack Propagation Surcharge Condition Pour Pressure Distribution Stress-Strain Solver Boundary Condition Structural elements Forces Water Condition Safety Factor Stage Construction Facing Condition 49
Soil constitutive model The proper soil constitutive model is an important issue and matter of discussion in numerical simulations of soil structures which affects the results. The analysis of tunnels construction in cemented soils with strain-softening behaviour is a very complex problem. In such materials, which are characterized by distinct peak and residual strength parameters, strength reduction can occur with increasing strain. Furthermore, the high stiffness of unloading paths in soil mass around tunnel section and of low strain in cemented soils affects the results. prediction of ground settlement strictly is influenced by the material constitutive model. 50
Soil constitutive model It is consequently difficult to determine which model to select for a particular task and the requirements for determination of parameters are not uniform. Usual constitutive model are : The Linear Elastic Model (LE) The Mohr-Coulomb Model (MC) The Drucker-Prager Model (HS) The Softening Model 51 Overview of Constitutive Models For Soils, by P.Lade, 2005
Soil constitutive model The Linear Elastic Model (LE) The simplest material model is based on Hooke's law for isotropic linear elastic behavior. Soil behavior is highly non-linear and irreversible. The linear elastic model is insufficient to capture the essential features of soil. The use of the linear elastic model may, however, be considered to model massive structures in the soil or bedrock layers. 52
Soil constitutive model The Mohr-Coulomb Model (Perfect-Plasticity) The oldest and still the most useful yield criterion for cohesive frictional materials is the empirical proposal made by Coulomb (1773) in his investigations of retaining walls Based Parameters: Basic idea of an elastic perfectly plastic model Plaxis (FEM Software) -Material Models Manual 53
Soil constitutive model Hardening Soil Model (Isotropic Hardening) The hardening soil model is an advanced model for simulating the behaviour of different types of soil, both soft and stiff soils, Schanz (1998). In the special case of a drained triaxial test, the observed relationship between the axial strian and the deviatoric stress can be well approximated by a hyperbola. later used in the well known hyperbolic model (Duncan and Chang, 1970). Based Parameters: 54
Soil constitutive model Hardening Soil Model (Isotropic Hardening) Hardening is assumed to be istropic depending on both the plastic shear and volumetric strain. For the frictional hardening a non associated and for the cap hardening an an associated flow rule is assumed. Plaxis (FEM Software) -Material Models Manual 55
Soil constitutive model M.C. and H.S. Soil Model Mohr-Coulomb Model (Perfect-Plasticity) Hardening Soil Model (Isotropic Hardening) Softening region Hardening region Hardening- Softening soil model for Elastic region cemented soils 56
Soil constitutive model Softening Soil Model Yasrobi et al (2013) presented a numerical results using softening soil model and Mohr-Coulomb elastic- perfectly plastic model and compared with monitoring results from Niayesh tunnel. the strain softening behaviour of the material was considered for by a reduction of the strength parameters of the elasto-plastic Mohr-Coulomb model with increasing a deviatoric plastic strain Based Parameters: profile of surface settlement for monitoring and prediction 57
Soil constitutive model Softening Soil Model to estimate the accuracy of results given by numerical modelling, the surface settlement given by monitoring records is considered as the reference and has been compared with results of model softening and elastic-perfectly plastic Mohr- Coulomb model 58
Soil constitutive model (Parameters) Dilatancy angle The relation between the dilatancy component from a triaxial compression test, the relative density, and the mean principal stress at failure suggested by Bolton (1986) Kulhawy and Mayne (1990) suggest taking as the dilatancy angle ψ . Bolton (1986) suggested from laboratory test data that for plane strain compression loading A simple and somewhat crude approximation for dilatancy angle, as often used in Plaxis analysis, is 59 Correlations of Soil and Rock Properties in Geotechnical Engineering; Jay Ameratunga, Nagaratnam Sivakugan, Braja M. Das; 2016
Numerical modeling tools (Software) Differential methods are more difficult and time consuming than boundary analyses (BEM), both in terms of model preparation and solution run times. As such, they require special expertise if they are to be carried out successfully. • Discrete element method • Finite difference method Continuum DisContinuum • Distinct element method • Finite element method Commercial Software's FLAC (Itasca) More use in soil and rock PLAXIS (PLAXIS BV) More use in soil Phase2 (Rocscience) More use in rock SVSoild (Soil Vision Systems Ltd.) More use in soil DIANA (TNO) More use in soil and rock ANSYS (ANSYS, Inc.) More use in soil and rock ELFEN (Rock field software Ltd.) More use in rock ABAQUS (SIMULIA) More use in soil and rock VISAGE (VIPS Ltd.) More use in soil and rock GeoStudio More use in soil 61
Numerical Modeling of Geotechnical projects Foundation engineering Deep Foundation- Driven Concrete pile Shadegan Steel Complex 62 SAP (structural analysis)
Numerical Modeling of Geotechnical projects Excavation Based Parameters: Results: -Deformation and Settlements E Young's modulus υ Poisson's ratio - Facing stresses (Shotcrete, Concrete Wall, Berlani … ) φ Friction angle c Cohesion - Tendons force (Nail, Anchor, … ) Ψ Dilatancy angle E un/re Unloading/reloading stiffness m power- dependency of stiffness R f Failure ratio 63
Numerical Modeling of Geotechnical projects Excavation Deep Excavation (Anchorage & Waller) 43m Access to Tunnel 64
Numerical Modeling of Geotechnical projects Tunneling Axial Forces Bending Moments 65 Finite Element Modeling with Plaxis
Numerical Modeling of Geotechnical projects Improvement of soft soil ground DSM method 66
Construction Methods of Deep Excavations: 1- NAILING OR ANCHORAGE 2- STRUTS SUPPPORTS 3- SOLDIER PILE&LAGGING 67
Construction Methods of Ramps (Nailing) Structure & tower- Air Exchange of Niayesh South tunnel of Niayesh North tunnel of Niayesh 68
Construction Methods of Ramps (Nailing) The area of probable cracks Contour of horizontal displacement Probable failure surface 69
Construction Methods of Ramps (Nailing) ADVANTAGES Less environmental impact: Less disruptive to traffic and environment; No need to embed any structural element: below the bottom of excavation as with soldier beams used in ground anchor walls; Time saving: More fast, uses typically less construction materials than ground anchor walls( shotcrete and steel); Relatively flexible and can accommodate relatively large total and differential settlements; Well performed during seismic events owing to overall system flexibility. 70
Construction Methods of Ramps (Nailing) DISADVANTAGES • Requires soil deformation to mobilize resistance; • Life lines and utilities: May place restrictions on the location, inclination, and length of soil nails in the upper rows; • Soil nail walls are not well-suited where large amounts of groundwater seeps into the excavation; 71
Construction Methods of Ramps (Anchorage) 43m Access to Tunnel 72
Construction Methods of Ramps (Anchorage) The area of Stress concentration Contour of horizontal displacement Probable failure surface 73
Construction Methods of Ramps (Anchorage) ADVANTAGES • Control of soil deformations; • Reduced construction time; • Low density: Under similar project conditions, the number of required soil nails per wall unit area is larger than the number of ground anchors. • Load Transfer: Soil nail transfer load along the entire length of the nails, whereas ground anchors are designed to transfer load only in the bond. • Load tests: each ground anchor is tested after installation and prior to being put into service to loads that exceed the design load. DISADVANTAGES • The possibility of the release locking force; • interaction of Life lines and utilities (similar nailing wall) 74
Construction Methods of Ramps (Piling) 11m Depth Cantilever Pile 75
Construction Methods of Ramps (Piling) ADVANTAGES • Column piles have enough stiffness for control the deflection of shallow excavation. • Passive soil resistance is obtained by embedding the piles beneath the excavation grade. • Contiguous piles are suitable in crowded urban areas Without the need for drilling. DISADVANTAGES • Adequate allowance must be made for installation tolerances. • For deep excavations, a cantilevered pile wall isn't generally sufficient to resist earth pressures. • A lot of project space is unused (diameter of piles) • Can't be used in high water table conditions without extensive dewatering. 76
Construction Methods of Ramps (Strutted Wall) Tehran Subway-Line 7- TBM 77
Construction Methods of Ramps (Strutted Wall) ADVANTAGES • have enough stiffness for control the deflection of shallow excavation. • Passive soil resistance is obtained by embedding the piles beneath the excavation grade. DISADVANTAGES • Occupying large space at excavation plant. • Increasing the truss’ size and weight in deep excavation. 78
Geomaple Quality control and quality assurance, instrumentation, Monitoring and back analysis
Necessity for Inspection 80
Necessity for Inspection Monitoring is necessary for each shoring&under ground project 81
Steps of Q.C / Q.A - aggregates Detail - cement Q.C / Q.A of INPUT - steel MATERIALS - water - admixtures - … - concrete - shotcrete Q.C / Q.A of CONSTRUCTION WITH - steel works (assembling or welding) INPUT MATERIALS - grout and grout injection - assembling - … - monitoring of movements and forces Q.C / Q.A OF FINAL - evaluate performance of system by some tests such as creep CONSTRUCTION test and etc. - … General 82
What is The Quality Control? The successful implementation of projects is dependent on Quality control For the efficiency of the Quality Control Project Management it will be necessary to have a fair and transparent mechanism with clear communication and instructions on site In Quality Control usually focus on: Quality of Design Progress Quality of Construction Quality of Input Materials Quality of maintenance 83
Goal of Monitoring? Monitoring of ground deformations in soil works is a principal means for : 1- Selecting the appropriate excavation method 2- Select support methods among those foreseen in the design 3- Ensuring safety during tunnel construction (including personnel safety inside the tunnel and safety of structures located at ground surface) 4- ensuring construction quality management 5- Improve construction method based on safety and cost simultaneously. We should have good communication between 3 Teams: Monitoring Team (record ground’s response during construction) Designer Team (back analyze and change first modeling based on back analyses' results) Construction Team (change method or materials base on new design) 84
Flow of Monitoring Information 85
Monitoring Plan Before considering monitoring plan, 3 points is important to specified: 1- Interior sensitive point and it’s limitations These points are important to mark with targets and record it’s deflection such as maximum deflection, maximum rotations. 2- Exterior sensitive point and it’s limitations These points are important to consider in modeling and recheck it’s predicted movement such as buildings, life lines and etc. 3- Amount of needed accuracy According to assumed accuracy, select appropriate monitoring system such as microgeodesy, inclinometer and etc. 86
Geomaple Laterally supported (braced) Unsupported (unbraced)
Geomaple Laterally supported (braced) Unsupported (unbraced)
Geomaple Soldier Pile and Lagging Secant/Tangent Pile Sheet Pile
Geomaple Soldier pile, Caisson and Lagging
Geomaple Secant Pile
Geomaple Tangent Pile
Geomaple Sheet Pile
Geomaple None urban shoring Deep excavation Mid excavation Urban shoring Trench excavation
Geomaple • Space limitation • Vibration • Soil movement
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Geomaple • Stability of building • TRCA requirement
Geomaple Stability of building • When a building is going to constructed in top of a slope more than 2:1 a slope stability analysis must be conducted as a part of structural design. • In this study a factor of safety of 1.5 for global stability of slope and Slide Surface proposed building should be considered.
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