MEA-serviced geotechnical and civil engineering projects can be found in every corner of the United States. As one of the leading geotechnical engineering consultants for subsidence engineering in the nation, prospective and abandoned mines can be expertly evaluated by MEA. In addition to the geotechnical design and forensic work related to subsidence, MEA has diverse experience with complex geotechnical civil engineering difficulties.
Several examples of more recent projects that MEA has been consulted on can be seen below:
Introduction: This project took place in Southeast Colorado. It involved 7 structures and over 700 drilled-in piers. The piers were 1 to 2 feet in diameter and up to 30 feet deep.
Description: The investigation included test borings, laboratory tests, and computer analyses. The geologic materials were difficult to recover and required different sampling methods as they range from soil to rock. In addition to many other tests, numerous swell tests were performed on the recovered sample.
Outcome:The design analyses determined the effect the potentially swelling ground would be negligible on the reinforced concrete piers. These piers were drilled into weathered to unweathered rock.
Introduction:An investigation was undertaken to determine why there was an immediate and dramatic failure during the paving of an asphalt road in Missouri.
Description: The analysis of the pavement design section involved test pits and laboratory tests of the subgrade soils, as well as review of the plans and specifications and the construction events.
Outcome: The results of this investigation disclosed design incompatibilities with the actual foundation conditions which resulted in heaving or shoving of the asphalt pavement during placement.
Introduction: Foundation design with a significant cut/fill scenario and an old underground coal mine.
Description: As the geotechnical engineering firm selected for the proposed IDNR building, we performed shallow and deep test borings. The challenges included design of the shallow foundation in a significant cut/fill scenario, as well as the concern of the collapse of the subjacent old coal mine. The collapse of the coal mine after the building was constructed would lead to subsidence and irreparable damage to the building.
Outcome: To stabilize the mine, plans and specifications were developed and successfully carried out remotely to grout the mine to 200 ft. deep. About 15,000 cy of grout was placed, as estimated, in the mine. Also, MEA provided recommendations to the structural engineer on the shallow foundation designed to be subsidence resistant.
Introduction:During the land development phase of a project, a massive landslide occurred into a water channel.
Description:This newsworthy event was investigated to determine the cause. The investigation included test borings, extensive laboratory testing, review of construction events, and well as the plans and specifications. With all the pertinent data gathered, both 2-D and 3-D stability analyses were performed.
Outcome: It was determined that the main cause of the failure was excessive loading of the ground surface with fill and the recession of the water level in the channel.
Introduction: The project involved design analysis of a braced cut required for an inlet structure that was to be installed at a levee along the Mississippi River near New Orleans.
Description: The design of the 30 ft. braced cut was complex because of the presence of soft clays, heavy railroad loadings, and other surface features. One of the contributing factors in the design was the concern for bottom heave.
Outcome: The braced excavation required the design and construction of relieving platforms and a sequenced excavation. A portion of the work was also done by open excavation and required slope stability analyses.
Introduction: Active room-and-pillar coal mine in southwest Indiana where the mine operator had concern for mine floor stability.
Description: To the operator in the early stages of mine development there were signs of weak floor conditions, MEA was consulted by the coal company. MEA inspected the mine, performed rock mechanics tests, reclassified much of the floor core, and performed stability analyses.
Outcome: MEA found the concerns about the mine floor were unfounded. Much of the floor rock was classified to be worse than what was actually present and weak floor conditions observed in the mine were determined to be minor.
Introduction: Concern was expressed for the condition of fairly new asphalt pavement associated with a trucking facility in New Jersey.
Description: The pavement was recently installed and there were some signs of distress. An investigation was undertaken which involved mapping the damage, sampling and testing the pavement structure, and performing load tests on the pavement.
Outcome: MEA determined the observed distress was not significant and that this damage was from truck loads above that which was considered during design.
Introduction: The project involved an 8 ft. diameter tunnel proposed in Atlanta, Georgia.
Description: The tunnel depth ranged from about 30 ft. to 70 ft. Along the tunnel alignment, the ground conditions transitioned from hard metamorphic rock to decomposed rock to soil. The design investigation involved testing borings, geologic mapping and logging, in place rock permeability tests, and laboratory testing.
Outcome: Tunnel support for the various ground conditions was recommended.