Teaching Geology to Civil, Architectural, and Environmental Engineering Students Patricia Gallagher, Ph.D., P.E. and Robert Swan Civil, Architectural and Environmental Engineering, Drexel University Earth Educators Rendezvous July 20 2016

Welcome to my favorite class! I might be an engineer, but I LOVE geology

Background Drexel is a quarter school with a 5-year co-op program Years 1 & 5: attend classes F, W, S quarters Years 2, 3, & 4: rotate 6 months of classes with 6 months of employment Quarters are 10 weeks long Ten weeks is a very short time for students to learn everything they need to know about geology!!!

Geologic Principles for CAE Engineers Text: Geology for Engineers & Environmental Scientists (Kehew) Four credit hours (quarter system) Two lectures (80 minutes) One lab (120 minutes) – meets in classroom with all 60-80 students! Students are 3rd or 4th year Civil & architectural students have taken or are taking mechanics & construction materials. Environmental students don’t take either mechanics or construction materials

Objectives Explain all aspects of the geologic cycle, including igneous, sedimentary and metamorphic rock forming processes, tectonic processes, and weathering and erosion processes. Identify and distinguish between igneous, metamorphic, and sedimentary rocks and explain how the inherent properties of each rock type influence the engineering properties of the rock. Explain how the engineering properties of geologic materials influence the design, construction, and maintenance of infrastructure and environmental projects

Objectives Explain how infrastructure projects are influenced by their topographic, hydrologic, surficial soil and underlying geologic settings. Interpret rock testing data and do basic stress-strain calculations using that data. Learn geologic and agronomic nomenclature and use it to interpret published reports, surveys and maps. Acquire background for further concrete, hydrology, environmental, and geotechnical study

How do we teach about engineering properties? Minerals and Rocks Focus on the intrinsic properties of minerals and rocks & how those properties influence the engineering properties Crystalline vs clastic rocks Formation processes and how they influence mechanical properties Assignments focus on the origin of construction materials Concrete Steel Brick

Example: Engineering in Different Types of Rocks Different types of rocks vary greatly in suitability for different engineering projects Questions to ask/answer: What types of rocks are present? How are they distributed? How have the rocks been changed or altered?

Example: Engineering in Sedimentary Rocks Difficult to generalize  Wide range in lithology Wide range in degree of lithification ENGINEERING PROPERTIES VARY BASED ON ORIENTATION OF BEDDING PLANES AND OTHER SEDIMENTARY STRUCTURES

Example: Important Considerations for Engineering in Sedimentary Rocks Bedding orientation Direction and amount of slope critical Horizontal bedding good Bedding parallel to downslope angle of slope BAD! Cementation: Well-cemented sandstones & limestones usually okay for foundation support & excavations but watch out for water infiltration in limestone, as it can lead to KARST formation

Example: Difficulties with Engineering in Sedimentary Rocks Engineering properties CHANGE after deposition/lithification Strength may increase after compaction, cementation Strength may decrease upon weathering (shales are especially susceptible because they weather to clay minerals) FRACTURES, JOINTS, DISCONTINUITIES WEAKEN ROCK & INCREASE FLOW OF WATER

Example: Engineering in Sedimentary Rocks Typical exam question: Select 2 considerations related to engineering in the following material: A highway road cut through shale with bedding inclined at 35° from the horizontal (see sketch below). (Choose the best two answers) Usually strong with few limitations for construction Bedding planes act as zones of weakness Slopes cut parallel to bedding planes may be problematic and need rock bolts; slopes perpendicular to bedding planes should have adequate stability Strength depends on cementation, particle size and shape, and particle mineralogy Dashed lines indicate proposed cut slopes, solid lines indicate bedding planes

How do we teach about engineering properties? Rock mechanics Stress-strain behavior of rocks Rock testing & analysis of results Engineering classification of rocks and rock materials Factors affecting the strength of the rock mass as compared to intact specimens Assignments and labs focus on analysis of rock core data to calculate rock quality designation, modulus ratio and rock mass rating Stress strain behavior: nonlinear behavior; plastic vs ductile, effect of confining pressure & temperature, influence of asperities on strength Rock testing: unconfined compression, direct shear, unconfined compression, Brazilian tensile, Mohr’s circle Discontinuities, weathering, defects,

How do we teach about engineering properties? https://upload.wikimedia.org/wikipedia/commons/thumb/c/c1/Bakken_Core.JPG/900px-Bakken_Core.JPG Rock mechanics Assignments and labs where rock core data is analyzed to calculate rock quality designation, modulus ratio and rock mass rating Unconfined compression Triaxial compression - gneiss Mohr’s circle- gneiss Calculate unconfined compressive strength, tangent modulus, modulus ratio, shear strength, Use triaxial results to calculate unconfined compressive strength and compare results with actual test results RQD, RMR 𝜎a= 𝐹𝑜𝑟𝑐𝑒 𝐴𝑟𝑒𝑎 ∈=change in length/initial length Et50=σa 50%ϵ Mr=Et50/σa 𝜎3=𝑚𝑖𝑛𝑜𝑟 𝑝𝑟𝑖𝑛𝑐𝑖𝑝𝑎𝑙 𝑠𝑡𝑟𝑒𝑠𝑠  𝜎1=𝑚𝑎𝑗𝑜𝑟 𝑝𝑟𝑖𝑛𝑐𝑖𝑝𝑎𝑙 𝑠𝑡𝑟𝑒𝑠𝑠= 𝜎3 +𝛥𝑃  𝛥𝑃=𝑑𝑒𝑣𝑖𝑎𝑡𝑜𝑟 𝑠𝑡𝑟𝑒𝑠𝑠  𝜏=𝑐+ 𝜎 σa = 2 C tan (45 + 𝛷 2 )

How do we teach about engineering properties? Structural geology Focus on the discontinuities in rock masses and their influence on the strength, settlement and permeability characteristics of the rock mass Use case histories (e.g. dams and dam disasters) to illustrate how to engineer in different types of rock

How do we teach about engineering properties? Earthquakes and earthquake engineering Focus on site response (i.e. soft soil versus rock) to earthquake motion Overview of designing earthquake- resilient structures Structural damage intensity for different height buildings related to depth of soil and fundamental period of soil. Tall buildings sustain maximum damage when constructed on long-period soil deposits (after Kehew, 2006) Increasing fundamental period of soil

How do we teach about engineering properties? Geomorphology For different landforms, we use the following approach: Geology  geologic processes/weathering  specific landform  soils/rocks  engineering information/potential problems at a site

Where do we go from here? We are currently in the process of flipping the class Main topic areas Introduction Rocks and Minerals Structural Geology Geomorphology Inaugural offering of flipped class: Winter 2017

Questions?