Geotechnical Engineering

The current rules can be found in PDF format HERE.

The scoring rubic can be found HERE. (3/17/17)


IMPORTANT:

If you have not submitted the GeoPile design report, you can submit the report until the 25th March, 2017. If you submitted the report and did not receive a conformation email from Prof Khire, that means your report has not been received.

Grade penalties for late submission will be applied as follows.

If received before, 5 PM, 15 March - No Penalty

If received before 5 PM, 16 March, 1 Point

If received before 5 PM, 17 March, 3 Points

If received before 5 PM, 20 March, 5 Points

If received before 5 PM, 25 March, 10 Points

If received AFTER 5 PM, 25 March, you will not be able to participate in the competition.

Please email your design reports by the above stated deadline(s) with a filename of 2017GeoPile.School_Name.pdf to Prof. Khire at mkhire@uncc.edu.  The scoring rubric will be updated soon to reflect this.


 

 

Objectives:

The objective of the UNC Charlotte GeoPile competition is to design a wooden pile and install it in a mechanically stabilized earth (MSE) retaining wall in which Kraft paper is used as the reinforcement. The competition objectives for students are to:

 

  1. Design an MSE wall by maximizing its surcharge for a given amount of reinforcement material;
  2. Design and fabricate a wooden pile to be installed in the MSE backfill by maximizing its uplift load, which will be installed in the MSE backfill; and
  3. Participate, share best practices and learn from others in the regional conference at the UNC Charlotte.   

 

Background:

The ASCE Geo Institute (GI) has been conducting the national GeoChallenge or GeoWall Competition for a number of years. This GeoPile competition to be held at UNC Charlotte is broadly based on the rules developed for the national competition, with a major change related to the design of a wooden pile to carry the maximum uplift load. The GeoPile competition uses the sand box that is used for the national competition. Hence, if you have participated in the national competition, you probably have fabricated a sand box at your school.

 

Eligibility:

Only one team per school will be allowed to compete. A team consists of a maximum of ten (10) students, consisting of no more than two (2) graduate students. Each team must designate a captain, who will be the point of contact for the team. For competition testing purposes, up to four (4) team members may be present to assist in the preparation and testing. All team members must be enrolled students at the date of the national competition.

 

Design Report Submittal:

A design report submission is required prior to the competition. The design report score will count towards the total score for the overall competition. Greater accuracy in the report compared to the results obtained during the competition testing will yield a higher score.

 

Required Report Content:

 

  1. Cover page with name of institution, student names and status (graduate, undergraduate) of each team member, identification of team captain with email address, and name, title, and email address of the faculty advisor.
  2. Material properties used in the design including methods (lab tests, correlations, analytical, empirical or numerical model(s), assumptions, etc.) used to obtain the properties.
  3. For the MSE wall and wooden pile, a description of the engineering design and construction procedures used, including assumptions, equations, and models.
  4. A complete description of the geometry and placement of all reinforcing elements. Note that you will be provided with a fixed dimensions of the Kraft paper and you may use it all. No bonus points for using less amount of paper.
  5. A complete description of the geometry of the pile, including all dimensions, and the weight of the pile with the hook that will be used to pull the pile during uplift testing.

 

Report Formatting Requirements:

 

  1. Length: Maximum three (3) pages (not including references and cover page).
  2. One-inch margins, single spaced, and 12 point Times New Roman font.
  3. All pages after the cover page shall contain a header identifying the team and a footer with the page number.
  4. The entire design report must be submitted in a single pdf format file with a filename of 2017GeoPile.School_Name.pdf. For example, UNC Charlotte file name should be 2017GeoPile_UNCC.pdf.

 

Design reports will be scored by a panel of practicing engineers and professors. Scoring criteria will include formatting and presentation, rationale and accuracy of design equations, material properties, and assumptions. “Trial and error” designs will be penalized. The scoring rubric will be provided with detailed rules in the next mailer.

 

The complete design report must be submitted in pdf format via email to Prof. Milind V. Khire, (mkhire@uncc.edu) by 5 PM, March 15, 2017. The subject line must include “GeoPile 2017 Submittal.” The sender will receive confirmation of receipt. Delayed submission will have a scoring penalty.

 

Sandbox:

The MSE wall will be constructed within an apparatus hereafter referred to as a sandbox (Fig. 1). Each team shall bring their own sandbox to the competition. Painting and addition of school or sponsor logos and other decorations to the exterior of the sandbox are encouraged. The sandbox shall be made up of a bottom and four vertical sides with no top. The front panel will be removable, as shown in Figure 1. The removable box panel will be in place during wall construction and removed after construction to expose the MSE wall.  The sandbox will be required to have:

  1. exterior walls and base constructed of any grade of plywood not to exceed ¾-inch (19 mm) thick;
  2. planar inside surfaces with the natural plywood finish;
  3. a removable front as shown in Figure 1. Panels must be flush with the base of the box and held into place with threaded inserts, screws, hinges or other easily removable fasteners;
  4. a full-sized base that extends no more than 3/4 of an inch (19 mm) beyond the base of the wall once the front panel has been removed;
  5. a steel tie rod designed to keep the two fixed sides of the box parallel after removal of the facing panel;
  6. all dimensions of the sandbox as shown in Figure 1.
  7. all templates removed after wall construction and before testing.

 

 

Fig. 1. Sandbox design

For convenience (but not required), sandboxes may be designed so they can be transported as flat pieces and reassembled at the competition site. Sandboxes will be checked for compliance at the pre-competition captains’ meeting. Teams will have until 9:00 am local time the day of the competition to correct any compliance issues. Any team with a box out of compliance at the start of competition will be penalized.

 

Backfill Material:

The backfill material will be clean sand provided by competition organizers on site. The sand will be dry and rounded to sub-rounded sand which conforms to Unified Soil Classification System (USCS) classification of SP. Percent finer at 50% passing (d50) is expected to lie between 0.8 mm to 1.5 mm. The backfill material must be used “as-is”, i.e. no water, additives, or chemical stabilizers should be placed in the backfill material.

 

Competition organizers will make reasonable efforts to ensure the competition backfill materials meet the specifications. However, these numbers may change once a source of sand is secured by the competition organizers. All teams will be notified of any changes. Teams will be allowed to examine a sample of the competition backfill at the captains’ meeting. No backfill samples may be removed from the meeting room. Teams may modify their wall design and/or predicted pile uplift load at this time if they desire, but with penalty.

 

Wall Materials:

Each team is responsible for supplying their own materials except the facing material, reinforcing material and the adhesive tape to be provided by the organizers.

  1. Facing shall be prepared using Poster Board having dimensions specified in Fig. 2. The Poster Board is 22” x 28”, white, Grammage 194 g/m2, Office Depot Item # 858277.
  2. Reinforcement shall be prepared from 60-lb. Kraft paper (Grammage: 97.7 g/m2; Office Depot Postal Wrap Item # 444835). Each team will be provided with a 24” wide x 3.5” long strip (total area ~ 84 sq. inches) of the 60-lb Kraft paper. Each team can cut this strip of paper into reinforcements as per the design proposed by the team. Reinforcements must not have any joints where two or more reinforcements are joined using an adhesive. Reinforcements should not be modified by any adhesive applied at the surface except where the reinforcement is tied to the poster board used for the wall facing.
  3. Adhesive material will be heavy duty, clear, 2” wide polypropylene package tape (Office Depot, Item# 650457, 2” x 22.2 yd with dispenser).

The teams will be expected to fabricate the reinforcements and attach it to the facing at the site to ensure every team uses the same type and quantity of the reinforcement, facing and the adhesive.

Key goals are to maximize the uplift load capacity of the wooden pile installed within the MSE backfill with a team specified surcharge placed on the backfill around the pile. There are no restrictions on the shape or geometry of reinforcing elements, except that all reinforcement must be cut from the given quantity of the Kraft paper. 

 

Pile Materials:

Each team is responsible for supplying their own materials for design, preliminary testing, and competition. The pile should be made up of any natural, uncoated, cylindrical sample of wood having a diameter ≤ 5 cm (2 inches) and length of 60 ± 0.6 cm (24 inches) with a hook fastened into one of the flat surfaces for uplift load testing (Fig. 3). Many online hardware stores refer to this wooden pile as a round dowel. The pile will be placed vertically in the backfill which can be compacted using specified methods. Each team may reshape the pile surface based on a design that will provide the best uplift capacity. The reshaping of the pile may include:

 

  1. drilling horizontal or inclined holes through the pile;
  2. shaving the surface to a new geometry (symmetrical or asymmetrical); and
  3. denting the surface of the pile using tools such as punch.

 

Fig. 2. Dimensions of Poster Board Wall Facing

 

 

When reshaping the pile, the following are not allowed:

  1. the creation of cavities that retain sand when pulled out of the backfill (however, a few particles sticking to the surface will not be a violation). Imagine placing the reshaped pile into a bath of water and pulling it out; if the pile does not retain pooled water, then a team is in compliance;
  2. the use of glue, glass fragments, or any other material applied to the surface of the pile; and
  3. diameter of the pile at any location exceeding 5 cm (2 inches).

Surcharge Plates:

Surcharge plates made up of steel having dimensions of ~ 13” x 13” and 0.5” thickness will be provided for adding surcharge to the pile. The use of surcharge will increase the uplift capacity of the pile. However, higher surcharge will lower the factor of safety of the MSE wall due to greater lateral pressure. Hence, you will need to design the wall with the maximum possible surcharge to yield the maximum uplift of the pile. The surcharge plates will have a 3” x 3” hole at the center to allow placement of the surcharge plate with the pile at the center. Each plate will weigh approximately 10 lbs (± 1 lb) and you will be provided with a maximum of 10 surcharge plates. Your design needs to make it clear how many surcharge plates you plan to use.

 

Fig. 3. Wooden pile – 5 cm diameter, 60 cm long (Hook not shown)

 

Construction Tools:

The following construction tools may be used and must be provided by the competing team (quantities of these items shall not be restricted):

  1. Pencils, pens, and markers;
  2. Rulers and straight edges;
  3. Levels;
  4. Manually operated cutting instruments (e.g., scissors, utility knifes, razor blades, hole punch);
  5. Cutting boards or mats;
  6. Design notes, calculations and drawings;
  7. Material handling and compaction tools consisting of any hand operated devices(electrically powered sand shaker will not be allowed);
  8. Screwdrivers (battery operated drills or screwdrivers may be used, but only to remove fasteners when removing the facing panels); and
  9. Temporary templates for use in any stage of competition. May be made of any material, must not have any moving parts, must be removed at the end of any stage in which they are used.

Note that the pile needs to be placed as vertical as possible in the backfill. Buckets and shovels will be provided by the competition organizers. It may be necessary for teams to haul backfill a distance of up to 50 feet.

 

Execution:

Construction of the apparatus will be done in the following stages with a maximum of 4 team members:

 

  1. Box and Reinforcement Assembly: Each team will bring the sand box (as per Fig. 1) in the final shape to the competition. The day before the competition, at the Captains’ meeting, all teams will be provided with the Poster Board for the wall facing, a strip of Kraft paper to be cut into reinforcements and the adhesive tape. All teams must fabricate and attach the reinforcements to the Poster Board by 9 am the morning of the competition (day after the Captains’ meeting). The reinforcements will be attached to the wall facing using clear, 2-inch-wide polypropylene packaging tape supplied by the competition organizers.  Once the reinforcements are attached to the wall facing, the wall facing will be inserted in the sandbox with the fourth panel of the sand box in place. All materials related to box construction and wall assembly (except the Kraft paper, Poster board, and adhesive tape)  must be supplied by each individual team prior to competition. 
  2. Pile Placement and Backfill: Team members will need to place the pile at the center of the box and then place and compact the backfill with the reinforcements extending from the wall facing into the backfill. The pile should have the top hook attached before the backfill is placed. The backfill sand will be supplied in bags for pouring or a team will be allowed to use other filling methods and tools such as 5-gallon plastic buckets. The backfill needs to flush with the top of the pile. If not, excess sand will be removed below the surcharge plate areas before the surcharge plates are placed and/or the pile is subjected to uplift testing.
  3. Loading and Pile Uplift Testing: This stage occurs in three steps:
    1. Placement of plate surcharge on the backfill above the pile as per the design report;
    2. Removal of the front wooden panel of the sandbox exposing the wall facing;
    3. Attachment of the pile hook to an uplift capacity testing device, then recording the maximum force just before the pile or the wall fail. Failure will be defined when the pullout deformation or distance ≥ 1 inch. The pullout load increments and duration over which the loads will be applied during the uplift testing will be provided at a later date.

 

During each step, the wall will be checked for the following three criteria:

  1. Excessive deformation (any portion of the wall extending outside imaginary planes extending vertically from base of sandbox);
  2. Excessive soil leakage (more than 30 cm3 of sand passing out of the sandbox); and
  3. Catastrophic failure.

When directed by the judge(s), the team shall remove the front panel of the sandbox. After the panel is removed, the judge(s) will wait one (1) minute and then check the above listed three criteria. If the wall does not fail catastrophically, then the pile will be subjected to uplift capacity testing.

The team will be penalized for excessive soil loss and excessive deformation. The team will score a zero for the pullout portion of the scoring if the wall fails catastrophically before it is subjected to uplift testing. If the wall fails catastrophically during the pile uplift stage, the maximum uplift load carried by the pile just before the failure will be used for scoring. During any stages of the execution, if a situation not described in these rules arises, the judges will make the decision on how to proceed and how to score the team. The decision will be final.

 

Design Changes:

Teams may change their design between the time the design report is submitted and the wall is tested. The potential design changes a team is allowed to make are as follows:

  1. the shape and layout of reinforcements;
  2. the specified surcharge; and
  3. the predicted uplift capacity of the pile.

 

Scoring:

The total score will be computed from scores in individual components of the GeoPile competition. The components include:

  1. Design Report;
  2. Aesthetics of the Sandbox; and
  3. Net uplift capacity (uplift load at failure – the weight of the pile with the hook) of the pile.

 

Points will be deducted for:

  1. Non-compliance of sandbox, wall facing, reinforcements, and pile reshaping and fabrication;
  2. Excessive deformation of catastrophic failure of the wall at any stage except during the pile uplift capacity testing stage;
  3. Structural failure of the pile or the pile hook attached to the pile.

 

Scoring criteria rubric will be presented at a later date.