Process Nevada Sand Property Tests Future Work • The Los Angeles Department of Water and Power has decided to make immediate changes to its open reservoir system in Southern California, due to emerging State and Federal water quality regulations. • Regulations have been implemented to replace the existing open reservoirs with buried, reinforced-concrete, water reservoir structures. SMART Program University of Wisconsin-Madison University of Colorado-Boulder Los Angeles Department of Water and Power http://engineering.mit.edu/live/news/1479-how-can-we-prevent- walls-from-collapsing-in Introduction Centrifuge Box Modifications Acknowledgements Why Care? Seismic Soil-Structure-Interaction and Lateral Earth Pressures Near Buried Water Reservoir Structures in Southern California Miguel Frias (1,2) , Shideh Dashti (3) , Valerie Tetro (4) , Christina Jones (4) 1 Summer Multicultural Access to Research Training 2 University of Wisconsin-Madison 3 Department of Civil, Environmental and Architectural Engineering 4 University of Colorado-Boulder Research Objective Figure 1. Headworks Reservoir Site. Abstract Sensor Installation Sieve Analysis Strain Gauges • Measure total amount of pressure distributed along the sand face wall • Pressure Sensors 12, 14, and 16 not included Pressure Sensors • Measure bending moment distributions acting on retaining wall Specific Gravity Defined as the ration of the unit weight of a given material to the unit weight of water. = + − Where Ws (Weight of soil), Wfw (Weight of flask + water), Wfws (Weight of flask+water+soil). = 60 60 + 677.9 − 715.3 ≡ 2.65% (1) (2) • Earthquakes have long been feared as one of nature’s most terrifying phenomena. Engineers now understand the origin of earthquakes and know that they must be accepted as a natural environmental process. Arriving without warning, the earthquake can, in a few seconds, create a level of death and destruction. • “You have to build in a way that allows the earthquake energy to be absorbed. Our objective as engineers is to increase the absorption” – Professor Buyukozturk Figure 2. Damage portion of the Golden State Freeway during the 1994 Northridge earthquake in Los Angeles. Pluviation Test • To determine how uniformly distributed our Nevada Sand is in the container • Higher energy = greater relative density and vice versa • Target density's: 40%, 60%, 80% Table 1. Strain Gauge Resistance. Strain Gauge 12, 14, 16 not included. Table 2. Pressure Sensor Resistance. Figure 4. Graph plotting Grain Size vs. Percent Passing. Graph demonstrates average grain size was between .5-.1 mm. Figure 3. AutoCAD drawings on left. Final project on right. Figure 5. Running a pluviation test. Evaluate the reliability of different types of pressure sensing technologies in capturing lateral earth pressures imposed by the backfill of Nevada Sand. Pressure Sensor Calibration • Spin at 60% density numerous times to compare data • Rotate wall vertically to measure lateral earth pressures • Run centrifuge test under dynamic loading Figure 6. Graph plotting Drop Height vs. Density. Figure 8. Linear correlation between theoretical pressure and voltage output resulting in calibration factor of sensors. Figure 7. Graph showing spin up and spin down within centrifuge. Each plateau represents 10 g levels. Highest on this graph is 50 g. Figure 9. 15 g-ton centrifuge. The Los Angeles Department of Water and Power has decided to make immediate changes to its open reservoir system in Southern California, due to emerging State and Federal water quality regulations. Regulations have been implemented to replace the existing open reservoirs with buried, reinforced-concrete, water reservoir structures. These structures will be surrounded by a number of active faults. The performances of these types of underground structures restrained at the base and roof during earthquake loading is currently not well understood. There are no reliable analytical tools for evaluating seismic lateral earth pressures acting on these structures, which is an important design parameter. To address this gap, centrifuge experiments were performed to study soil-structure-interaction effects and seismic earth pressures near model reservoir structures under earthquake loading. The primary objective focuses on evaluating the reliability of different types of pressure sensing technologies in capturing static lateral earth pressures imposed by the backfill of Nevada Sand. These tests were conducted using a simple, aluminum cantilever retaining structure with a fixed base under an increased gravity load induced by a 15 g-ton centrifuge. The data obtained will compare the pressure sensors and their reliability in capturing static earth pressures. This will test the hypothesis that tactile pressure sensors with minimum stiffness and high sampling rate are the only sensors at this time that are capable of providing reliable pressure measurements in the geotechnical centrifuge.
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Process Nevada Sand Property Tests
Future Work
• The Los Angeles Department of Water and Power has decided to make immediate changes to its open reservoir system in Southern California, due to emerging State and Federal water quality regulations.
• Regulations have been implemented to replace the existing open reservoirs with buried, reinforced-concrete, water reservoir structures.
SMART Program University of Wisconsin-Madison University of Colorado-Boulder Los Angeles Department of Water and Power http://engineering.mit.edu/live/news/1479-how-can-we-prevent-
walls-from-collapsing-in
Introduction Centrifuge Box Modifications
Acknowledgements
Why Care?
Seismic Soil-Structure-Interaction and Lateral Earth Pressures Near Buried Water Reservoir Structures in Southern California
Miguel Frias (1,2), Shideh Dashti (3), Valerie Tetro (4), Christina Jones (4)
1 Summer Multicultural Access to Research Training 2 University of Wisconsin-Madison
3 Department of Civil, Environmental and Architectural Engineering 4 University of Colorado-Boulder
Research Objective
Figure 1. Headworks Reservoir Site.
Abstract
Sensor Installation
Sieve Analysis
Strain Gauges
• Measure total amount of pressure distributed along the sand face wall
• Pressure Sensors 12, 14, and 16 not included
Pressure Sensors
• Measure bending moment distributions acting on retaining wall Specific Gravity Defined as the ration of the unit weight of a given material to the unit weight of water.
𝐺𝐺 =𝑊𝐺
𝑊𝐺 + 𝑊𝑊𝑊 −𝑊𝑊𝑊𝐺
Where Ws (Weight of soil), Wfw (Weight of flask + water), Wfws (Weight of flask+water+soil).
𝐺𝐺 =60𝑔
60𝑔 + 677.9𝑔 − 715.3𝑔 ≡ 2.65%
(1)
(2)
• Earthquakes have long been feared as one of nature’s most terrifying phenomena. Engineers now understand the origin of earthquakes and know that they must be accepted as a natural environmental process. Arriving without warning, the earthquake can, in a few seconds, create a level of death and destruction.
• “You have to build in a way that allows the earthquake energy to be absorbed. Our objective as engineers is to increase the absorption” – Professor Buyukozturk
Figure 2. Damage portion of the Golden State Freeway during the 1994 Northridge earthquake in Los Angeles.
Pluviation Test • To determine how uniformly
distributed our Nevada Sand is in the container
• Higher energy = greater relative density and vice versa
• Target density's: 40%, 60%, 80%
Table 1. Strain Gauge Resistance. Strain Gauge 12, 14, 16 not included.
Table 2. Pressure Sensor Resistance.
Figure 4. Graph plotting Grain Size vs. Percent Passing. Graph demonstrates average grain size was between .5-.1 mm.
Figure 3. AutoCAD drawings on left. Final project on right.
Figure 5. Running a pluviation test.
Evaluate the reliability of different types of pressure sensing technologies in capturing lateral earth pressures imposed by the backfill of Nevada Sand.
Pressure Sensor Calibration
• Spin at 60% density numerous times to compare data
• Rotate wall vertically to measure lateral earth pressures
• Run centrifuge test under dynamic loading
Figure 6. Graph plotting Drop Height vs. Density.
Figure 8. Linear correlation between theoretical pressure and voltage output resulting in calibration factor of sensors.
Figure 7. Graph showing spin up and spin down within centrifuge. Each plateau represents 10 g levels. Highest on this graph is 50 g.
Figure 9. 15 g-ton centrifuge.
The Los Angeles Department of Water and Power has decided to make immediate changes to its open reservoir system in Southern California, due to emerging State and Federal water quality regulations. Regulations have been implemented to replace the existing open reservoirs with buried, reinforced-concrete, water reservoir structures. These structures will be surrounded by a number of active faults. The performances of these types of underground structures restrained at the base and roof during earthquake loading is currently not well understood. There are no reliable analytical tools for evaluating seismic lateral earth pressures acting on these structures, which is an important design parameter. To address this gap, centrifuge experiments were performed to study soil-structure-interaction effects and seismic earth pressures near model reservoir structures under earthquake loading. The primary objective focuses on evaluating the reliability of different types of pressure sensing technologies in capturing static lateral earth pressures imposed by the backfill of Nevada Sand. These tests were conducted using a simple, aluminum cantilever retaining structure with a fixed base under an increased gravity load induced by a 15 g-ton centrifuge. The data obtained will compare the pressure sensors and their reliability in capturing static earth pressures. This will test the hypothesis that tactile pressure sensors with minimum stiffness and high sampling rate are the only sensors at this time that are capable of providing reliable pressure measurements in the geotechnical centrifuge.
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