Evaluation of a Slope Stability in Nebraska with Biopolymer Treated Soil
Amairani J Salazar
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07/28/2021
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Description
Slope degradation is a critical aspect to naturally occurring slopes and civil engineering. More often than not, failure of slopes occurs due to gravitational force, water seepage, or surface erosion which develops an inconvenience to infrastructure that is settled upon suspected soil. The purpose of this research is to determine whether soil strengthening with biopolymers can prove to be effective on the field as it was in the lab. To achieve this some field data collection will be acquired from Verdigre Slope, in Knox County, Nebraska. The moisture content and hydraulic conductivity data of the soil monitored will be attained and then applied into a computer modeling software to compare slope degradation, between biopolymer mixed soil with that of untreated soil.
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- [00:00:01.230]Hello, my name is Amairani Salazar. In this video,
- [00:00:04.530]I will be presenting the research topic I have been working on this summer,
- [00:00:08.580]entitled the Evaluation of a Slope Stability in Nebraska with Biopolymer
- [00:00:13.080]Treated Soil.
- [00:00:15.480]I will first introduce a brief background. Landslides are the second most
- [00:00:20.160]common geological
- [00:00:21.090]hazard constantly posing potential threats to cities and towns. Due to an
- [00:00:25.740]increase in urbanization.
- [00:00:27.450]the demand to manufacture different design projects and civil infrastructure has
- [00:00:32.010]become rather critical. As these
- [00:00:34.260]new developments began to expand on hilly terrain or mountains,
- [00:00:37.910]understanding the nature of landslide hazards is therefore necessary.
- [00:00:42.900]Soil treatment is a geotechnical engineering practice that focuses on
- [00:00:47.220]improving soil characteristics, such as strength,
- [00:00:49.920]permeability and durability against environmental factors.
- [00:00:55.110]Over the last years,
- [00:00:56.340]the study of microbial induced biopolymers have established a new construction
- [00:01:00.360]binder capable of being incorporated into soil treatment,
- [00:01:04.110]which can be applied in the following areas of engineering.
- [00:01:08.910]The first of those is Soil Strength, Erosion control,
- [00:01:14.160]Ground and Pavement, as well as Soil Water Retention.
- [00:01:19.080]The purpose of this study is focused on comparing the model for Verdigre Slope
- [00:01:22.950]located in Knox County,
- [00:01:24.330]Nebraska with untreated and biopolymer treated soil,
- [00:01:28.050]to determine whether Xanthan Gum can be effective in slope stabilization
- [00:01:32.550]based on severe weathering conditions.
- [00:01:36.540]The materials we will be using include our soil which is clay. The biopolymer
- [00:01:41.360]studied, Xanthan Gum and the geotechnical software, GeoStudio.
- [00:01:47.220]Now we will begin taking a look about the methods.
- [00:01:53.990]The first of those methods was to study literature review, for biopolymers,
- [00:01:58.260]Xantham Gum thing and identify key soil parameters.
- [00:02:01.820]In addition to that review saturated and unsaturated flow to determine
- [00:02:05.660]important values for the unsaturated conditions of soil,
- [00:02:10.670]The use of GeoStudio
- [00:02:11.420]was implemented into the research to develop two types of analysis.
- [00:02:16.070]Seep/W is focused on solving the transient
- [00:02:18.950]seepage analysis based on severe precipitation while Slope/W is focused on
- [00:02:23.900]the slope stability analysis, based on the factor of safety.
- [00:02:27.980]The last of the steps was to compare the findings based on the two analysis
- [00:02:31.850]types.
- [00:02:34.880]This is a table that includes all of this unsaturated and physical soil
- [00:02:38.750]properties of clay that were found in the literature view and applied in the
- [00:02:41.990]model. Here are the results obtained from GeoStudio.
- [00:02:47.570]Figure 1. shows the model of Verdigre
- [00:02:49.280]Slope along with all of the soil layers and the biopolymer treated
- [00:02:54.020]section.
- [00:02:55.430]The arrow points out the boundary conditions taken into account for our first
- [00:02:59.770]analysis type, transient seepage.
- [00:03:04.270]The next figure displays the pore water pressure and distribution based on
- [00:03:07.780]severe precipitation and as can be seen,
- [00:03:10.300]water was able to infiltrate the slope after heavy rainfall,
- [00:03:13.630]but the overall effect is negligible. Here
- [00:03:17.850]we have figure 3 which shows the factor of safety for,
- [00:03:22.680]figure a),
- [00:03:24.090]the slope with untreated soil and figure b) the biopolymer treated soil.
- [00:03:29.940]The overall factor of safety increased.
- [00:03:35.250]The following graph displays the factor of safety over a period of time due to
- [00:03:39.510]extreme precipitation. The purple color shows the
- [00:03:43.770]biopolymer treated soil. While
- [00:03:46.410]the dark color shows the untreated soil.
- [00:03:51.540]Some of the benefits for this research include an overall level of safety
- [00:03:56.400]and slope stability. Since biopolymers are organic material,
- [00:04:00.750]they serve as a sustainable solution as opposed
- [00:04:04.240]to other binding materials and Xanthan Gum is feasibly
- [00:04:08.700]economic.
- [00:04:11.390]In addition to that, continued studies and research could improve futuristic soil
- [00:04:16.090]behavior and practices
- [00:04:18.120]therefore resulting in a reduction of civilian
- [00:04:22.890]life alterations, such as danger, costs, and time.
- [00:04:28.260]Some current challenges biopolymers face include some economic disadvantages
- [00:04:33.510]since the majority of biopolymers are expensive. Durability,
- [00:04:37.170]is up for debate since they are organic therefore will decompose over time.
- [00:04:42.600]Lastly, biopolymers are extremely sensitive to water,
- [00:04:46.470]which raises questions during the wetting and drying cycles.
- [00:04:53.010]In conclusion, heavy rainfall had minimal effect on the pore water distribution as
- [00:04:57.570]seen on figure 2. In reference to the slope stability.
- [00:05:02.310]the standard factor of safety for landslides is 1.5
- [00:05:06.480]and according to the results. both slopes were above this average.
- [00:05:11.250]Biopolymer Xanthan.
- [00:05:12.320]Gum has proved to be effective overall against severe weathering by increasing the
- [00:05:17.160]factor of safety by 5%.
- [00:05:22.140]Funding for this project was provided in part by the National Science
- [00:05:25.320]Foundation. I would like to thank
- [00:05:28.010]Dr. Jongwan Eun for being my faculty advisor
- [00:05:30.570]as well as Sina Mousavi and Yuan Feng,
- [00:05:34.380]my graduate student mentors. Thank you.
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