Guidelines for Investigating Geologic Hazards and Preparing Engineering-Geology Reports with a Suggested Approach to Geologic-Hazard Ordinances in Utah, Second Edition

Rockfall geologic hazards are widely distributed. Due to their concealed nature, rockfalls are difficult to investigate using traditional contact survey methods, and the hazards they pose affect major projects and people’s safety. Reproducing methods, including scene survey and movement process analysis, are primary tasks used to prevent these hazards; however, few reconstruction methods can directly apply the parameters of the rockfall geologic hazards obtained by the scene survey to evaluate the movement process. To address this problem, a method of reproduction based on oblique photography and three-dimensional discontinuous deformation analysis (3D-DDA) is proposed; the method consists of three key techniques (oblique photography, 3D rock block system modeling, and 3D rock block system analysis). First, geometric characteristic parameters of the terrain, rockfall, and discontinuities are extracted based on oblique photography using an unmanned aerial vehicle (UAV). Second, the block system model of rockfall is reconstructed by using 3D computational geometry theory and taking these geometric characteristic parameters as an input. Finally, the whole evolution process of rockfall geologic hazard, including initiation, movement, and accumulation, is simulated by the 3D-DDA method. To verify the practicability of this reproduction method, a typical rockfall geologic hazard, located in the K8 + 050 section of the Gaohai expressway, Yunnan, China, is studied. In addition, the characteristics of 19 dangerous rock masses in the survey area are clarified, and the geometric features of the discontinuities in the rock masses are extracted based on oblique photography using an UAV. The block system model of a potential rockfall is reconstructed, the movement trajectory is simulated by the 3D-DDA method, and the evolution process of velocity and kinetic energy of the rockfall verifies that the spatial layout of the current three-level passive protective nets system is reasonable. The case study indicates that the proposed method provides a geological and mechanical model for the risk assessment of rockfall geologic hazards.

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Economic Impacts from Geologic Hazard Events on Colorado Department of Transportation Right-of-Way

Transportation Research Record Journal of the Transportation Research Board ◽

10.3141/2646-02 ◽

2017 ◽

Vol 2646 (1) ◽

pp. 8-16

Author(s):

Mark Vessely ◽

Scott Richrath ◽

Ermias Weldemicael

Keyword(s):

Economic Impact ◽

Performance Management ◽

Economic Impacts ◽

Productivity Loss ◽

Department Of Transportation ◽

Geologic Hazard ◽

Right Of Way ◽

Geologic Hazards ◽

Colorado Department ◽

Work Orders

The economic impacts from geological hazards that occur within or adjacent to Colorado Department of Transportation (DOT) right-of-way can be measured in support of exposure estimation for risk-based asset and performance management. The events include rockfalls, rock slides, landslides, debris flows, and sinkholes and can be categorized as routine maintenance, regular program activities, and urgent response. The statewide economic impacts from geologic hazards were grouped into two categories: ( a) direct costs for maintenance labor and equipment, engineering, and construction and ( b) indirect costs, including property damage, injury or fatalities, traveler delay, lost productivity, loss of revenue to businesses and communities, and environmental impacts. Annual direct department costs from geologic hazard events average about $17 million to $20 million, which includes maintenance staff response to approximately 8,500 work orders each year. Most work orders are high-frequency events that are addressed daily by maintenance staff. Conversely, some events occur less frequently and have a larger economic impact, particularly for users and communities. In 2014, the economic impact from geologic hazards on Colorado DOT roadways was estimated to be nearly $30 million. Historical data indicate that the 2014 estimate is conservative when high-volume roadways are affected or when more large events occur in a single year. For example, the economic impact for two rockfall events on I-70 in 2004 and 2010 was estimated to be more than $40 million each, adjusted to 2015 dollars. When average Colorado DOT direct expenses are included, the economic impact in those years may have exceeded $60 million.

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