Hazard-Mitigation of Civil Infrastructure through. Dynamic Compaction. Kameron Kaine Raburn

Transcription

1 Hazard-Mitigation of Civil Infrastructure through Dynamic Compaction Kameron Kaine Raburn

2 Effects of Liquefaction

3 Image source: How Liquefaction works

4 How can we Mitigate effects of soil Liquefaction? Dynamic Compaction

5 Image source: Mitigation of Soil Soil Liquefaction Liquefaction Ground improvement through Dynamic Compaction has been noted, as a means of improving the soils for supporting structural loads and a remedial measure against soil liquefaction due to seismic shaking (Feng et. al, 2013). Niigata Earthquake 1964

6 An Introduction to Dynamic Compaction Dynamic Compaction (DC) is a method of, densification where the energy produced by DC destroys the original soil structure and expels air and water out from voids, forcing soil particles into a denser state through consolidation (Feng et. al, 2013). Through this process, a series of high-energy impacts improve weak soil conditions by introducing a significant amount of energy into the surface of the soil.

7 The Process of Dynamic Compaction To achieve the desired state of soil compaction, tampers made of concrete, measuring approximately 100 to 400 (kn) are released into a free-fall from a height ranging between 10 and 40 meters above the existing soil. To ensure a uniform soil treatment area, a grid system is predetermined an then followed by the operator of the pounder.

8 Waves generated by dynamic compaction Compression, Shear & Rayleigh

9 Wave Types Body Waves: Compression (P) & Shear (S) propagate radially outwards from the pounder s impact point along a hemispherical wave front Surface Waves: Rayleigh propagate radially outwards along a cylindrical wave front (Hamidi, et. al, 2009)

10 P, S, & Rayleigh Waves Generated by Dynamic Compaction

11 P & S Waves

12 Image source: When is Dynamic Compaction Necessary? Presence of Cohesive & Granular Soils with: High void ratio that will produce significant settlement Saturated sand layers with high void ratio and in a potential earthquake environment have the potential to produce liquefaction

13 Influencing Factors of Dynamic Compaction Design Ground Property Aspect Soil type Groundwater table Underlying compressible layer DC Technique Aspect Weight & shape of tamper Drop height Grid pattern Number of impacts Time delay between impacts (Feng et al., 2011)

14 Preliminary Geotechnical Investigation Field Work Soil Sample Collections Laboratory Work Soil Sample Properties Analyzation What is the quality of the soil? What are the parameters for treatment? Depth of Treatment Treatment Area

15 Soil Sample Types Disturbed Sample Undisturbed Sample Used for determining intrinsic properties: Liquid Limit Plasticity Index Grain Size Used for determining: State Properties

16 Is DC a proper treatment for your soil type?

17 Is DC a proper treatment for your soil type?

18 Soil Response to Dynamic Compaction Granular Soils Vs. Cohesive Soils

19 Granular vs. Cohesive Soils Pounder Footprints: Granular Soils Collapse Volume Cohesive Soils Heave Volume

20

21 Calculation of Influence Depth D = n W*H Where: 0.3 n 0.6 D: maximum depth of improvement n: constant value of soil W: mass of tamper H: height of free fall Menard and Broise (1975) offered a simplified empirical relationship for a preliminary estimate of the depth of improvement after DC dmax = (WH), where dmax = depth of improvement in meters; W = tamper weight in tons; and H = tamper drop height in meters)

22 Depth of Influence Treatment Depth: Loose or weak soils Higher n value Greater depth of influence Stiffer or dense soils Lower n value reduced depth of influence

23 Seismic Destruction Consideration Seismographic Monitoring Annoyance to Humans Destruction of Infrastructure Building structures Pipelines Sensitive equipment Limitations of use due to location (Hwang et.al, 2005) Image Source:

24 Seismographic Considerations 50+ (mm/s) Structural Failure 10 (mm/s) Damage to structures 2.5 (mm/s) Annoyance to Humans

25 Dynamic Compaction outcomes Reduce voids in old fills and collapsible soils Reduced settlement under new loading Increase bearing capacity allowing higher load supporting capacity Reduce liquefaction potential for structures, landfill liners, dams, and embankments.

26 Results and Conclusions Foundation Stabilization Decreased porosity of soil will result in soils being less compressible Dynamic compaction is an applicable treatment process for soils prone to liquefaction in areas with increased earthquake or seismic activity Cost effective compared to to pile driving reduction of future maintenance costs/foundation repair

27 Questions?

28 Acknowledgments Universitat Politècnica València National Science Foundation University of Texas at Arlington

29 Thank you Ricardo and Miguel for all you have done to help me!

30 Bibliography Athanasopoulos, G., & Pelekis, P. (2000, February 19). Ground Vibrations from sheet pile driving in urban environment: measurements, analysis and effects on buildings and occupants. Soil Dynamics and Earthquake Engineering, Feng, S.-J., Shui, W.-H., Tan, K., Gao, L.-Y., & He, L.-J. (2011). Field Evaluation of Dynamic Compaction on Granular Deposits. Journal of Performance of Constructed Facilities, 25 (3), Feng, S.-J., Tan, K., Shui, W.-H., & Zhang, Y. (2013). Densification of desert sands by high energy dynamic compaction. Engineering Geology, Hamidi, B., Nikraz, H., & Varaksin, S. (Unknown). Dynamic Compaction Vibration Monitoring in a Saturated Site. Perth: Curtin University. Hwang, J., & Tu, T. (2005, December 5). Ground vibration due to dynamic compaction. Soil Dynamics and Earthquake Engineering, Kirsch, K., & Bell, A. (2013). Ground Improvement (3 ed.). Boca Raton, Florida, United States of America: CRC Press Taylor & Francis Group. Minaev, O. (2014). Development of Dynamic Methods for Deep Compaction of Slightly Cohesive Bed Soils. Soil Mechanics and Foundation Engineering, 50 (6), Mohammed, M. M., Hashim, R., & Salman, F. A. (2010). Effective improvement depth for ground treated with rapid impact compaction. Scientific Research Essays, 5, Pan, J., & Shelby, A. (2002). Simulation of dynamic compaction of loose granular soils. Advances in Engineering Software, Rodriguez, A. T., Montejano, J. C., & Sanz, R. V. (2015). Dynamic Compaction Evaluation Using In SITU Test. Madrid: Menard.

31 International Research Experiences for Students Program Hazard Mitigation Of Civil Infrastructure Through Dynamic Compaction of Unstable Soils Kameron Kaine Raburn College of Engineering University of Texas At Arlington UNIVERSIDAD POLITÉCNICA DE VALENCIA What is Dynamic Compaction? July 2015 Valencia, Spain Dynamic Compaction (DC) is a method of, densification where the energy produced by DC destroys the original soil structure and expels air and water out from voids, forcing soil particles into a denser state through consolidation (Feng et. al, 2013). Through this process, a series of high-energy impacts improve weak soil conditions by introducing a significant amount of energy into the surface of the soil (Kirsch et. al, 2013). The Process of Dynamic Compaction Design of Dynamic Compaction Treatment Plan The figure to the left portrays a most basic concept of the Dynamic Compaction process. In the upper portion of the figure you can see a crane hoisting a specified weight into the air, followed by the release of the weight from a calculated height. Rayleigh waves are seen visibly radiating along the surface of the ground, away from the tamper impact zone. Finally, you observe the seismic compression and shear waves radiating through the earths crust. To achieve the desired state of soil compaction, tampers made of concrete, measuring approximately 100 to 400 kilo-newtons are released into a free-fall from a height ranging between 10 and 40 meters above the existing soil (Feng et. al, 2013). To ensure a uniform soil treatment area, a grid system is pre-determined an then followed by the operator of the pounder (Hamidi, et. Al, 2009). When engineering a treatment plan for an unstable soil there are two major categories to consider in the design process: the ground property aspect and the DC technique aspect (Feng et. al, 2013). There are many variables encompassed in the ground property aspect, including, soil type, the groundwater table, and the underlying compressible layer (Feng et. al, 2011). Dynamic Compaction aspects to consider include, weight and shape of tamper, the drop height, the grid pattern, the number of impacts, the termination criterion at each impact point, and the time delay between passes (Feng et. al, 2011). Preliminary Geotechnical Investigation of Soil Properties Due to the nature of dynamic compaction, the treatment should be limited to soils containing a low Liquid Limit and Plasticity Index percentage. The soils Plastic Index percentage should be less than 20 percent, and the Liquid Limit Index should be less than 35 percent. This region may be found in the graph to the left in Zone A As observed in the graph to the right, there are three zone classifications in which soils can be divided into for the purpose of determining the applicability of Dynamic Compaction. Soils with a high percentage of large grains present are most ideal for the Dynamic Compaction treatment process. Funded by the National Science Foundation Preliminary Geotechnical Investigation of Soil Grain Size Compression, Shear & Rayleigh Waves Generated by DC Immediately upon impact of the pounder with the soil surface, a number of different wave types are transmitted through the soil. These waves can be broken into two different categories: body waves and surface waves. Body waves are made up of shear and compression waves. These waves, propagate radially outwards from the pounder s impact point along a hemispherical wave front. On the other hand, the surface wave or Rayleigh waves, propagate radially outwards along a cylindrical wave front. (Hamidi, et. al, 2009) Autor: Kameron Kaine Raburn Advisor: Ricardo Valiente Sanz Co-Advisor: Miguel Angel Carrión Carmona Acknowledgements University of Texas At Arlington Soil Response to Dynamic Compaction: Granular Soils vs. Cohesive Soils Depending on the type of soil being treated and the input energy, a variety of results can be expected from the soil (Kirsch et. al, 2013). The two main soil types in which dynamic compaction is applicable to are granular and cohesive soils. Different soil affects can be expected from the treatment these two types of soils. Compaction of a granular soil will result in a collapse volume surrounding the footprint of the pounder. This means additional dirt will need to be brought in to fill this newly created void. In the contrary, compaction of a cohesive soil will yield a raised heave volume in the immediate area surrounding the foot print of the pounder. This protruding heave volume will then need to be leveled. The two different scenarios can be seen in the diagram below. Thank you to everyone who helped to make this research experience possible. This would not have been possible if it were not for the hard work of UTA Professor Dr. Nur Yazdani and PVAMU Professor Dr. Lisa Thompson. Also, thank you to my UPV mentors Dr. Ricardo Valiente and Dr. Miguel Ángel Carrion for all of your time. I greatly appreciate all you have done. References Feng, S.-J., Tan, K., Shui, W.-H., & Zhang, Y. (2013). Densification of desert sands by high energy dynamic compaction. Engineering Geology, Feng, S.-J., Shui, W.-H., Tan, K., Gao, L.-Y., & He, L.-J. (2011). Field Evaluation of Dynamic Compaction on Granular Deposits. Journal of Performance of Constructed Facilities, 25 (3), Hamidi, B., Nikraz, H., & Varaksin, S. (Unknown). Dynamic Compaction Vibration Monitoring in a Saturated Site. Perth: Curtin University. Kirsch, K., & Bell, A. (2013). Ground Improvement (3 ed.). Boca Raton, Florida, United States of America: CRC Press Taylor & Francis Group.