Author: David Stevens

Vertical Earthquake Drains for Soil Liquefaction Mitigation

Photo of a verticle earthquake drain

Vertical earthquake drains developed by Nilex, Inc.

Limited blast liquefaction testing, vibration testing, and centrifuge testing suggest that vertical drains can be effective in preventing earthquake-induced soil liquefaction and associated settlements or lateral spreading. However, no full-scale drain installation has been subjected to earthquake-induced ground motions. This lack of performance data under full-scale conditions has been a major impediment to expanding the use of this technique for mitigating liquefaction hazards.

To determine the viability of large diameter (4 in.) prefabricated vertical drains for preventing soil liquefaction and associated settlements under full-scale conditions, the pooled fund study no. TPF-5(244) was initiated in 2013 by UDOT, Brigham Young University (BYU), and other state DOTs from California, New York, and Alaska, in conjunction with the National Science Foundation’s George E. Brown Jr. Network for Earthquake Engineering Simulation (NEES) Facility at the University at Buffalo (UB) of The State University of New York.

Photo

NEES-UB 20-ft high laminar box with hydraulic actuators.

In August and September 2014, two test series with vertical drains in liquefiable (loose and saturated) sand were completed using the laminar shear box and high speed actuator system at NEES-UB. Tests involved level ground conditions with two drain spacings: 4 ft for the first series and 3 ft for the second series. For each drain spacing, the soil profile was subjected to a total of nine sinusoidal motions at increasing peak base accelerations of 0.05g, 0.10g, and 0.20g. The settlement of the soil profile was measured using surface settlement plates, string potentiometers, and Sondex profilometers. Pore pressure transducers were used within the sand at various depths to measure pore water pressures. Accelerometers and LVDTs were located along the height of the shear box to define the acceleration and deflection profiles induced by the shaking at the base. Example data plots are shown below.

A few video recordings from the first series of tests at NEES-UB are available for viewing at this link. Progress reports and the overall scope of work for the study are provided on the web page for study no. TPF-5(244).

Graph

Settlement and excess pore pressure ration versus depth plots during the first shaking test at 4-ft drain spacing, with 15 cycles of shaking and 0.05g peak acceleration.

Remaining tasks on the project include data analysis, comparison with previous tests on untreated sand, evaluating predictive methods, and preparing the final report regarding drain effectiveness. If full-scale tests prove the effectiveness of the drainage technique, significant time and costs savings can be achieved for both new construction and for retrofit situations, as compared to other mitigation techniques.

This guest post was written by Kyle Rollins, PhD with Brigham Young University and David Stevens, PE with UDOT Research Division and was originally published in the UDOT Research Newsletter.

Highlights from the 2014 Annual Efficiencies Report

Efficiencies within UDOT often generate cost savings for the public and the Department through better utilization of resources and innovative technologies. At the end of each year, UDOT prepares an efficiencies report which summarizes key efficiency initiatives from the year. The annual report fulfills a requirement for UDOT to describe the efficiencies and significant accomplishments achieved during the past year to the State Legislature. UDOT Senior Leaders use the report in presentations during legislative committee meetings.

Following are the key efficiency initiatives summarized in the FY 2014 report:

  • SUCCESS Framework Initiative
    • Statewide Access Management Program
    • Preconstruction Project Scoping
    • Ports of Entry Truck Processing
    • Snow and Ice Control
    • Procurement System
    • Heavy Duty Truck Maintenance
  • Report Auto Generator for Roadway “As-Builts”
  • Uinta Basin Rail
  • Outdoor Advertising Control Map
  • Automated Queue Warning Detection System
  • Cement-Treated Asphalt Base
  • Citizen Reporter Program
  • Real-Time Winter Road Weather Index Performance Measurement
  • Variable Speed Limit in Parley’s Canyon
  • Snow Fencing Efficiencies

One example from the 2014 report is the SUCCESS Framework Initiative, a set of management principles from the Governor’s Office of Management and Budget, designed to boost the quality and efficiency of government services, with the goal of improving government operations and services by 25% by the end of 2016. One of the six major systems that UDOT is focusing on for the SUCCESS Framework is the Statewide Access Management Program. With a lot of hard work and collaboration, the Access Management Team reduced the time and labor cost required for processing access permit applications. As a result, the per-permit processing cost was lowered from $1,709 to $1,532 ($177 per permit), providing approximately $42,000 in annual cost savings to UDOT.

Citizen Report ScreenshotAnother example from 2014 is the Citizen Reporter Program, which enlists trained volunteers to report on road weather conditions along specific roadway segments across Utah. This citizen crowd-sourcing contributes to the quantity, quality and timeliness of traveler information, especially in rural areas. As a result, UDOT saves approximately $250,000 annually from the reduced need for road weather instrumentation, and from efficiencies in storm forecasting.

The UDOT Research Division coordinates each year with UDOT Senior Leaders and the Communications Office to collect and compile write-ups on the past year’s key efficiency initiatives. We appreciate all of the UDOT Regions and Groups that submitted FY 2014 efficiencies topics and write-ups on the key items. This process will start again in August for FY 2015.

The 2014 and earlier annual reports are available online at www.udot.utah.gov/go/efficiencies.

This post was originally published in the UDOT Research Newsletter.