Undermining and settlement of sub grade soils of railway track and load out canopy area of Cereal Food Processors, Inc. plant, Ogden Utah.
Concrete Stabilization Technologies, Inc. Field Consultant, Jonathon George was contacted by Scott Roberts of Cereal Foods, Inc. concerning settlement issues around the load out area for rail cars at the cereal processing plant located in Ogden, UT.
Settlement occurred due to a water main leak which had undermined sub grade soils around approximately 120 linear feet of railway track. The area of rail canopy is supported by five pillars. The middle of the five pillars showed the greatest amount of settlement of 1 to ½ inches while the other pillars in both directions had also experienced settlement, but to a lesser degree.
The settled area of the Cereal Food Processor plant is in area used to load rail cars with grain. The area is used on a daily basis with empty rail cars rolling into the canopy area, being loaded with grain, and then moving the heavy load to other areas of the plant for production. This being a vital part of the plant’s production sequence, taking the tracks out of service for an extended period of time, would not only slow production, but affect the plant’s profit margin. Due to the non-invasive process and rapid curing time of CST geopolymers, the track was only out of service for a couple of hours.
Soil test results revealed compromised soil in the settled areas at a depth of three to four feet below the surface grade. No settlement of the tracks themselves had occurred, however, tests performed beneath the tracks did reveal soft soils. As a preventative measure against future settlement in the track area, it was recommended to the owner to treat soils beneath the rail ballast as well.
Initial soil tests were made in the areas of the canopy pillars and track sub grade. Results of the testing indicated very soft soil three to four feet down into the sub grade area. Penetrometer testing also revealed soft soil beneath the track area as well.
CST’s deep injection method was used to stabilize the affected areas. Repair work began at the center of the east track. 5/8” holes were drilled and probes placed into the sub grade soils. Geopolymer was injected through the probes into the soil on five feet center and four feet below the top of the concrete/asphalt overlay. The purpose of the injections between the tracks was to fill any voids, stabilizing the weak soil, and interlocking the sub grade with the ballast, preventing future settlement.
Once the track area was completed, injections were then made beneath the spread footer of each of the five pillars to stabilize soil and prevent settlement. The two pillars with the most severe settlement were addressed first. Injections were made at depths of one, three, and five feet below the bottom of each spread footer. For the remaining three pillars, injection was made at one and three feet below the bottom of each spread footer. Close monitoring of surface movement at the surface was made during injection, and movement was detected from all injections.
Time Savings: Repairs were completed in one day. Track was useable immediately following injection of sub grade soils.
Cost Savings: Conservatively reduced repair costs by 50% (versus reconstruction).
Longevity: Repairs permanently stabilized the source of the settlement – weak soils, mitigating future settlement and damage to canopy as well as rail track line through area.