Geotechnical Manual of Instruction

Geotechnical Manual of Instruction

The UDOT Geotechnical Manual of Instruction (GMOI) has been developed to provide the Geotechnical Design staff and consultants with UDOT policies, procedures, practices, and technical criteria. The GMOI consists of the written manual, methods and tools, checklists, and GMOI Revision Memoranda. The information presented in the GMOI is expected to help fulfill UDOT’s mission of providing a safe and efficient transportation system.

For convenience, the “Current GMOI Written Manual” includes the most recent full release of the written manual along with revisions to date in a single document. Please verify that the copy includes the most current interim revisions. Previous published versions of the written manual, and the Drawings, Checklists, and GMOI Policy Memoranda are provided below.

Written Manual

The written manual provides technical direction and expands upon and clarifies design and construction requirements as specified by AASHTO Specifications.

Geotechnical Manual of Instruction – September 2017
Revisions to the GMOI between published editions are issued through GMOI Policy Memoranda and are referred to as interim revisions. Requirements detailed in the memoranda are effective and enforceable on the effective date listed in the memorandum.

GMOI Written Manual Revision Log.
A copy of the GMOI Written Manual including interim revisions is provided above for your convenience.

Drawings

Under Development

Checklists

Geotechnical checklists provide guidance for field reconnaissance, subsurface exploration and geotechnical testing. However, checklists are not all inclusive, and geotechnical engineers must review the project documents and include all information required to reflect the designer’s intent.

Field Reconnaissance
Updated January 26, 2018

Geotechnical Subsurface Exploration
Updated January 26, 2018

Geotechnical Laboratory Testing
Updated January 26, 2018

GMOI Policy Memoranda

The current list of retaining wall systems approved for use on UDOT projects in accordance with the GMOI is updated as needed.

Previous lists of approved wall systems are included with the GMOI Policy Memoranda below.

Policy Memoranda

A GMOI Policy Memorandum establishes interim revisions to GMOI policies, procedures, practices and technical requirements. The Structures Division issues memoranda as needed to ensure that the GMOI remains up to date and appropriately reflects changes in needs and requirements. Requirements detailed in the memoranda are effective and enforceable on the effective date listed in the memorandum and in the GMOI Revision Log.

Memorandum Title	Effective Date
G17-W03 – Approved Retaining Wall Systems	April 02, 2021
G17-W02 – Approved Retaining Wall Systems	April 27, 2020
G17-W01 – Approved Retaining Wall Systems	October 10, 2019
Structures Memo Approved MSE and PMG List	September 10, 2018

Subscribe to the Department E-mail Notification List for Consultant Services to receive notice at time of distribution.

Forms and Templates

Field Work Forms

The GMOI provides a field work form for use in projects to obtain and document permission to access private property. In order to view and print the form correctly and ensure use of the latest form, download the form before each use.

Form	Purpose
Exploratory Drilling Permit to Enter Updated January 26, 2018	To obtain and document permission to access private property directly from the property owner.

Design Assistance Templates

Template	Purpose
Simplified SPT Performance-Based Assessment of Liquefaction and Effects method (SPLIQ)	If a site specific Newmark Analysis is not performed, compute and compare deformations estimated using at least two of the methods defined in Appendix A11 of the AASHTO LRFD Bridge Design Specifications. Compare the results to those obtained using the SPLIQ.
SPLIQ Users Manual
Method for Determining Surcharge Fills Considering Post-Construction Secondary Compression	Used to compute surcharge in the absence of project specific laboratory test data of secondary consolidation settlement parameters for surcharged soils.
Construction Settlement Spreadsheet	Used for independent evaluation of the projected construction settlement.