Geotechnical Engineering

Study lessons

1. 1

   Soil Properties and Classification

   How to move between void ratio, porosity, water content, degree of saturation, and unit weight using the soil phase diagram, plus the Atterberg limits and USCS/AASHTO classification systems the CELE tests directly.

   15 min
2. 2

   Effective Stress, Shear Strength, and Foundations

   How to apply Darcy's law, compute effective stress under a water table, size Rankine lateral earth pressures, and estimate bearing capacity with Terzaghi's equation, the computation core of the HGE geotechnical items.

   15 min
3. 3

   Shear Strength and Lateral Earth Pressure

   How to apply the Mohr-Coulomb criterion, read total versus effective stress strength, tell the UU, CU, and CD triaxial tests apart, and size Rankine active, passive, and at-rest pressures and the thrust on a retaining wall.

   15 min
4. 4

   Bearing Capacity and Foundations

   How to apply Terzaghi's bearing capacity equation, use shape factors for strip, square, and circular footings, separate gross, net, and allowable pressures with a factor of safety, estimate immediate and consolidation settlement, and size a pile from skin friction and end bearing.

   15 min
5. 5

   Soil Compaction and Ground Improvement

   How to run the standard and modified Proctor tests, read maximum dry density and optimum moisture content off the compaction curve against the zero-air-voids line, check field quality with relative compaction, relative density, and the sand-cone method, and match compaction equipment and ground-improvement methods to the soil.

   15 min
6. 6

   Seepage and Flow Nets

   How to apply Darcy's law to seepage, build and read a flow net, compute the discharge q = k H (Nf/Nd), find uplift pressure and the exit gradient, check the factor of safety against piping and the quick condition, and handle anisotropic permeability.

   15 min
7. 7

   Slope Stability

   How to read the factor of safety of a slope, run the infinite-slope analysis with and without seepage, grind the method of slices by the ordinary Fellenius and Bishop simplified routines, use Taylor's stability number, and choose between short-term undrained and long-term drained strength.

   15 min
8. 8

   Soil Exploration and Sampling

   How holes are advanced with augers, wash, and rotary boring, how the standard penetration test is run and its N value corrected to N60 and (N1)60, how the cone penetration test profiles the ground, how the area ratio measures sample disturbance, and how a blow count is turned into a friction angle or undrained strength.

   15 min
9. 9

   Deep Foundations and Pile Design

   How a single pile carries load through skin friction and end bearing, the alpha and beta methods for shaft resistance, group efficiency and block failure, negative skin friction, and what pile load tests and dynamic formulas tell you.

   15 min
10. 10

    Retaining Structures

    How to proportion gravity and cantilever retaining walls, check them against overturning, sliding, and bearing, size the embedment of cantilever and anchored sheet-pile walls, and set strut loads for braced excavations.

    15 min
11. 11

    Soil Dynamics and Liquefaction Basics

    How saturated soils respond to cyclic loading, how to size the small-strain shear modulus from shear wave velocity, why loose saturated sand liquefies as pore pressure climbs and effective stress collapses, how to build the cyclic stress ratio and compare it against cyclic resistance for a factor of safety, and which soils are most susceptible.

    15 min
12. 12

    Consolidation and Settlement Analysis

    How a saturated clay sheds excess pore pressure and settles over time, how to read the compression and recompression indices off the e-log p' curve, how to size the primary settlement of normally and overconsolidated clays, how the coefficient of consolidation, time factor, and degree of consolidation set the rate, and how secondary compression keeps creeping afterward.

    15 min
13. 13

    Ground Improvement Methods

    How to densify loose granular ground with vibro-compaction, stone columns, and dynamic compaction, how to speed the consolidation of soft clay by preloading it with vertical (sand or wick) drains, and how permeation, compaction, and jet grouting plus lime and cement stabilization fix the soils compaction alone cannot reach.

    15 min
14. 14

    Reinforced Soil and Geosynthetics

    How a mechanically stabilized earth wall turns soil and layered reinforcement into a coherent gravity block, how to check each layer against tension rupture and pullout, how the reinforced mass passes the external sliding, overturning, and bearing checks, and how geotextiles and geogrids serve the four functions of separation, filtration, drainage, and reinforcement.

    15 min
15. 15

    Foundation Settlement and Allowable Limits

    How to estimate the immediate (elastic) settlement of a footing, separate total from differential settlement, convert differential movement into angular distortion against standard allowable limits, and see why footings settle quickly on sand but slowly on clay.

    15 min
16. 16

    Stress Distribution in Soils

    How the extra vertical stress from a foundation spreads and fades with depth, using the Boussinesq point-load solution and its influence factor, the 2 to 1 approximate method for footings, and the Newmark chart concept, with worked stress increases under a point load and under a rectangular footing.

    15 min
17. 17

    Mat and Raft Foundations

    How to decide when a mat replaces isolated footings, separate gross from net contact pressure, size a fully compensated (floating) foundation by excavation depth, and see how a mat spreads load to cut differential settlement.

    15 min
18. 18

    Earth Dams and Embankments

    How earth dams hold water with an impervious core and pervious shells, how to trace the phreatic line as a basic parabola, compute seepage through the body from q = k H (Nf/Nd) and from Kozeny q = k y0, check piping with the critical hydraulic gradient, size a graded filter by Terzaghi's rules, and judge which embankment slope governs.

    15 min
19. 19

    Braced Excavations and Cofferdams

    How a propped cut differs from a free wall, the Terzaghi and Peck apparent earth pressure envelopes for sand and clay, reading strut loads by tributary area, checking base heave in soft clay, the common cofferdam types, and controlling groundwater by dewatering.

    15 min
20. 20

    Pile Group Capacity and Settlement

    Why a pile group carries less than the sum of its piles, the Converse-Labarre efficiency and block-failure checks, minimum spacing and negative driving effects, and why a group settles far more than one pile using the equivalent-raft method.

    15 min
21. 21

    Negative Skin Friction and Downdrag

    How a consolidating fill or a dropping water table drags a pile down, where the neutral plane sits, how to size the dragload with the alpha and beta methods, how downdrag eats into the allowable load, and how a bitumen slip coat cuts the negative friction.

    15 min
22. 22

    Rock Mechanics Fundamentals

    How intact rock differs from the jointed rock mass, how to read RQD from a core run, unconfined compressive strength and its strength classes, the point load index with its size correction, discontinuities and the Rock Mass Rating idea, and how to estimate allowable bearing on jointed rock.

    15 min
23. 23

    Unsaturated Soil Mechanics

    How partly saturated soil holds water under tension, what matric suction ua - uw means, how to read a soil-water characteristic curve, how to size capillary rise with hc = 4 T cos(alpha) / (gamma_w d), how Bishop's equation sigma' = (sigma - ua) + chi(ua - uw) adds a suction term to the effective stress, and why wetting can collapse a loose soil.

    15 min
24. 24

    Soil Water and Capillarity

    Why water climbs into soil pores against gravity, how surface tension sets the height of capillary rise hc = 4 T cos(alpha) / (gamma_w d), how Hazen's hc = C / (e D10) estimates it from grain size, how the capillary zone splits into a fully saturated fringe and a partly saturated band, and how the tension u = -gamma_w z raises the effective stress by up to gamma_w hc above the water table.

    15 min
25. 25

    Vertical Drains and Preloading

    How a temporary surcharge preloads soft clay and how prefabricated vertical drains slash the consolidation time by shortening the drainage path from vertical to radial, covering the equivalent drain diameter dw = 2(a + b)/pi, the influence diameter de, Barron's radial degree of consolidation Ur = 1 - exp(-8 Tr / F(n)), the smear zone, and Carrillo's rule for combined vertical and radial flow.

    15 min
26. 26

    Expansive and Collapsible Soils

    Why some clays swell when wetted and shrink when dried, how plasticity index and activity grade swell potential, the free swell index test, estimating heave from the swell index with heave = Cs/(1 + e0) H log10(Ps/sigma_f'), collapsible loess and wetting collapse graded by CP = delta-e/(1 + e0), the collapse settlement CP x H, and how lime, moisture control, prewetting, and deep piers mitigate both hazards.

    15 min
27. 27

    Geotechnical Instrumentation and Monitoring

    How field instruments track a geotechnical structure as it is built and loaded, covering standpipe and vibrating-wire piezometers that read pore water pressure u = gamma_w hp, settlement plates and extensometers that log vertical movement and its rate, inclinometers that build a lateral displacement profile from delta = L sin(theta), load cells on struts and anchors, the observational method, and how trigger levels turn raw readings into decisions.

    15 min

Section practice test

35 test sets covering the whole Geotechnical Engineering section, 1050 original questions with explanations. After you finish the lessons above, prove it here. Randomized every run.