Complex Geotech / Major Foundation

Major Foundation / Complex Geotechnical Projects

US 41 Corridor Improvement, Brown County, WI

The USH 41 project is expanding and improving the highway corridor to accommodate more traffic and provide safer and easier travel along this 14 mile long segment. Key features of the improvement plan include interchange upgrades, added lanes and construction of roundabouts, embankments, bridges, flyover bridges, retaining walls, overhead sign structures and ponds. Large fill embankments are planned above soft soils.

GESTRA’s scope of work includes performing subsurface exploration, geotechnical engineering analysis, and preparing structural geotechnical reports (SGR) for 23 road bridges, 38 retaining walls and 12 sign bridges. Several flyover structures are included in the project.

GESTRA performed the following geotechnical services for the USH 41 project: reviewing WisDOT’s existing subsurface exploration reports and as-built plans for existing bridges and embankments, geotechnical laboratory testing, global stability and settlement analysis for the proposed embankments, and providing recommendations for the proposed ponds. GESTRA’s geotechnical laboratory testing services for USH 41 Reconstruction project include gradation analysis, unconfined compressive strength, one-dimensional consolidation, tri-axial testing of soil and compressive strength testing for rock samples. GESTRA is also contracted by Department to provide the geotechnical recommendations during the construction phase.

GESTRA completed geotechnical engineering reports for bridges (LRFD), flyover bridges (LRFD), retaining walls (ASD and LRFD), abutment walls (ASD and LRFD), culverts (LRFD) and overhead sign structures (ASD) in the USH 41 Reconstruction project. The geotechnical engineering analysis for these structures include pile axial and lateral capacity, calculation of down drag forces, pile drivability analysis, lateral squeeze analysis, sheet pile design recommendation, external and global stability analysis for retaining walls, caisson design and group analysis for the sign structures.

GESTRA completed design for embankment fill planned over soft soil using complex geotechnical analysis. The design in several areas included staged construction with installation of vertical wick drains. In areas where embankment failure could be prevented by shallow excavation and replacement, trenches were included with replacement of the soft soil with high friction angle material. GESTRA provided foundation recommendations for four flyover bridges connecting USH 41 and I-43 ramps considering results of on-site static pile load tests due to high variability in the soil profile.

Wis 441 Tri-County Project, Winnebago and Outagamie Counties, WI

Improvements are planned to approximately 6 miles of the existing WIS 441 roadway. This includes adding mainline capacity to WIS 441, reconstructing interchanges and adding a new parallel bridge for Little Lake Butte des Morts (LLBDM). Realignment will create new embankments over a portion of the project.

GESTRA is performing geotechnical drilling and SPT borings at depths between 10 and 100 feet. Subsurface exploration services also include performing rock coring in deep borings, monitoring well installation and evaluation of soft soil strength with in-situ vane shear testing as required based on site conditions. Borings were completed with truck rigs, ATV rigs and barge mounted rigs. Geotechnical laboratory testing includes gradation analysis, consolidation, unconfined compression and triaxial testing. Geotechnical analysis is being developed by GESTRA for bridges, MSE retaining walls, pavement, and new embankments (settlement and slope stability)The area has a significant amount of soft/low strength lean to fat clay deposits along with a history of excessive settlement and slope stability issues.

Soft soils would result in slope stability concerns and excessive post-construction settlement if traditional methods were used for embankment and retaining wall construction. GESTRA worked with the Department and the designers on the project to consider project constraints. GESTRA completed complex geotechnical designs for staged construction with installation vertical wick drains to improve the soft soil. GESTRA also completed the complex geotechnical analysis for the new 22 span pre-stressed concrete girder bridge that is being designed to cross the Little Lake Butte des Morts (LLBDM).

I-794 Gateway Project, Milwaukee, WI

The project included collaboration between the City of Milwaukee and the Wisconsin Department of Transportation. A successful project will create opportunity for future development along Milwaukee’s lakefront with creation of a significant parcel for downtown development. The project also improves access to the Third Ward, Discovery World, the Art Museum, and the festival grounds. The proposed improvement included the removal, realignment and reconstruction of the eastbound I-794 exit ramp to Lincoln Memorial Drive and the westbound I-794 entrance from Lincoln Memorial Drive. It included the reconstruction of Clybourn Avenue and the reconfiguration and reconstruction of Lincoln Memorial Drive from Michigan Street to Harbor Drive.

GESTRA’s scope of work included soil borings for retaining walls and bridges. Soil conditions include old fill over soft sediments including an organic soil layer. Cone Penetration Testing (CPT) has been performed at each ramp abutment location. CPT holes with continuous profiling were used to evaluate in-situ undrained shear strength, friction angle, relative density, unit weight, over-consolidation ratio, with pore-water pressure dissipation to estimate horizontal flow/hydraulic conductivity.

For bridge abutments and piers, pile analysis includes individual pile axial capacity, uplift capacity and lateral resistance (using LPILE software) following the LRFD approach. GESTRA is participating in project meetings with the City, WisDOT, and designers. The preliminary analysis and meetings have allowed for complex geotechnical solutions to be applied to meet the project schedule constraints.

Soft soils would result in excessive settlement, slope stability concerns, and potential bearing capacity problems for the planned retaining walls. GESTRA prepared a wall evaluation matrix to assess costs, advantages, and disadvantages of several wall types and ground improvement methods. Two methods have been developed to provide flexibility as the project schedule is finalized. Both include the use of soil improvement with vertical wick drains. GESTRA is completing the geotechnical design for the walls and bridges.

Vliet Street Municipal Interceptor Sewer, Milwaukee, WI

The existing Municipal Interceptor Sewer (MIS) between N. Hawley and N. 60th Street, on West Vliet Street is planned for replacement by trenchless installation of a new sewer using pilot tube micro tunneling, also called guided auger boring. This process uses a laser-guided small diameter pilot tube, installed by displacement methods similar to directional drilling, to establish the line and grade of the final product pipe, which is then installed by a variation of conventional auger boring techniques. Portions of the new sewer will be constructed nearly directly below the existing sewer, leaving about 3 feet of cover between the top of the new sewer and the bottom of the existing.

GESTRA prepared a report to present the results of the borings and laboratory testing, provide recommendations for MIS construction, and provide baseline values for expected groundwater and cobble/boulder obstructions.

An interpretation of the conditions into distinct soil units was provided to assist in planning of the project. A projection of the location of the soil units beyond the boring locations was done to provide an estimate of the conditions that are anticipated for construction. Recommendations related to MIS construction including support of manholes and soil parameters for shoring design were also included.
The report provided a contractual definition of assumed cobble/boulder obstructions and collected groundwater with respect to administration of a differing site condition clause.

I-39 Reconstruction, Dane County, WI

I-39/90 is one of the major transportation corridors in Wisconsin and is under design for improvements. The proposed improvements consist of the removal and reconstruction of the existing freeway lanes and addition of a third lane in each direction to create a six lane divided highway. The existing USH 51/STH 73, USH 51, and CTH N interchanges will also be redesigned and reconstructed. Existing bridge structures in the project area will also be reconstructed or widened. The approximate project length in GESTRA’s section of work is 19 miles.

GESTRA is performing geotechnical engineering analysis with responsibilities including reviewing soil and rock samples and laboratory testing results, geotechnical analysis and report preparation. Geotechnical engineering services included subsurface exploration and field operations with soil boring and sampling, laboratory testing, and geotechnical design of the bridges, embankments and subgrade evaluation.
The geotechnical aspects included subgrade design recommendations for roadway pavement, slope stability analysis, retaining wall foundation and external analysis, and bridge foundation recommendations. Retaining walls, slope stability and foundations analysis were completed following current LRFD procedures. The most complex sections for slope stability included the design of a crushed aggregate toe trench through a section of marshy soils adjacent to a major slope widening. Bridge foundations were predominately driven pile design which included vertical and lateral capacity analysis. Due to erratic elevations of weathered bedrock and IGM, some pile foundations require pre-boring to obtain minimum length for lateral capacity. Other bridge locations were evaluated for shallow foundation and driven pile foundations due to sloping bedrock.

Elm Road Power Generation, Oak Creek, WI

WE Energies increased the power production capacity of the Oak Creek facility by constructing a second plant, referred to as the Elm Road Generating Station. The plant was constructed in an excavated area in the bluff north of the existing plant on the shore of Lake Michigan. Preparation of the site required significant excavation (over 4 million cubic yards) and transportation of the excavated material.

GESTRA Engineering, Inc. (GESTRA) performed the subsurface exploration work for the project that included soil and rock drilling and sampling, well installation and monitoring, borehole pressuremeter testing, soil resistivity test, down hole shear wave velocity determination, in-situ hydraulic conductivity test. GESTRA also performed laboratory testing of soil and rock including consolidated undrained shear test with pore pressure measurement, unconfined compression test, one dimensional consolidation test, Atterberg limits determination, soil gradation-mechanical and hydrometer, moisture and organic content test, and sulphate,chloride and pH determination.

A total of 47 standard penetration soil borings to depths varying from 20 to 100 feet, for a total of 2750.5 lineal feet, was drilled for this project. Boreholes were advanced using hollow stem augers (4 ¼” and 2 ¼”ID) until saturated sands were encountered that required mud rotary drilling and were abandoned with bentonite slurry in accordance with applicable WDNR regulations.

STH 73 Reconstruction, Dane County, WI

STH 73 is a major alternate transportation route that was designed for improvements including roadway widening, culvert replacements and construction of a new overpass and ramp interchange.

GESTRA performed geotechnical engineering analysis with responsibilities including reviewing soil and rock samples and laboratory testing results, geotechnical analysis and report preparation. Geotechnical engineering services included subsurface exploration and field operations with soil boring and sampling, laboratory testing, and geotechnical design for a new bridge, multiple culvert replacement or widening, embankments and subgrade evaluation.
The geotechnical aspects included subgrade design recommendations for roadway pavement, slope stability analysis, and bridge/culvert foundation recommendations. Slope stability and foundations analysis were completed following current LRFD procedures. The most complex sections for slope stability in new embankments included the design subgrade correction and replacement to improve the factor safety and reduce overall settlement for bridge approaches. Slope stability analysis for major excavation areas was required and specific evaluation of sloping groundwater table and affect on the planned slope was performed. Bridge foundations were driven pile design which included vertical and lateral capacity analysis. Culvert locations required significant soil correction and recommendations for shoring due to construction occurring while adjacent traffic lanes remained open.

Foundation Evaluation Lunt Hall – Northwestern University, Evanston, IL

Lunt Hall is a three storied library building at the Northwestern University, in Evanston, Illinois. In 2004, a severe distress of the building structure was observed with an appearance of significant vertical movement and cracks in the foundation walls, settlement of the entrance and basement floor slabs, cracks-spalled and displacement of the mortar joints at many locations. The objectives of the project were evaluation of the foundation condition of the existing building and provide recommendations for rectification.

GESTRA’s scope of work included performing subsurface exploration, laboratory testing, groundwater monitoring, site inspection, reviewing initial investigation report, reviewing settlement monitoring data, forensic study and distress analysis, and preparing a report identifying the most likelihood of the reasons for foundation distress and presenting the recommended rectification procedures.

The subsurface exploration scope of GESTRA includes a total of 255 feet of standard penetration test (SPT) drilling to evaluate the surrounding soil of the existing Lunt Hall Building. GESTRA also installed two monitoring wells for continuously monitoring and to establish a static groundwater level around the building.

An initial investigation report prepared by Inspec, Inc. and settlement monitoring data performed by others were provided to GESTRA for review in order to complete the forensic study on the foundation distress of the existing building. Based on the information available of the existing building structure and surrounding conditions, subsurface investigation, instrumentation and laboratory test results, GESTRA completed distress analysis and identified the most likelihood of the reasons for distress of the existing building foundation and floor slabs. GESTRA also provided state-of-the-art recommendations on rectification procedures addressing the ground improvement alternatives with mud grout jacking and micropiles foundation support system.