MEMO
DATE: April 6, 2015 TO: Calvin Reed, P.E. Assistant Bureau Chief-Bureau of Structures and Geotechnical Services
ATTENTION: Chris Meyer, P.E. Senior Bridge Squad Leader
FROM: Denny J. Martin, P.G. Regional Geologist
RE: Geology Report Project 69-19 KA-1554-03 US-69 over Dry Branch Cox Creek Bridge No. 69-19-17.74 (135) Crawford County, Kansas
____________________________________________________________ The Bridge Foundation Report for the above listed structure is enclosed. This report can also be found on the KDOT Intranet http://kdotweb.ksdot.org/ in the Document Management System. If questions arise over the contents of this report, please contact the Chanute Regional Geology Office at (620) 431-1000 or by the following e-mails:
[email protected] or
[email protected]. If more reports are needed please make copies as required for distribution in your Bureau. An Engineering Geology Bridge Sheet has been drawn on the MicroStation Workstation. This file can be found at the following location in Projectwise: pw:\\DT00PW50.ksdot.org:KDOT_PW\Documents\Projects - K & KA\KA155403\Geology\dgn Attachments c:
Susan Eiseman, Assistant Bureau Chief-Construction and Materials James Metcalfe, P.E., District 4 Construction/Materials Engineer George Dockery P.E., Area 4 Engineer Debbie Stanley Regional Geology Offices Project File
BRIDGE FOUNDATION GEOLOGY REPORT 69-19 KA-1554-03 Bridge No. 69-19-17.74 (135) NB US-69 over Dry Branch Cox Creek 2.4 Miles North of Arma City Limits Crawford County ROBERT W. HENTHORNE, P.G. CHIEF GEOLOGIST By: Tyson LeSage, G.T. Denny J. Martin, P.G., Regional Geologist
Bureau of Structures and Geotechnical Services Geology Section
69-19 KA-1554-03 Bridge No. 69-19-17.74 (135) NB US-69 over Dry Branch Cox Creek 2.4 Miles North of Arma City Limits Crawford County
INTRODUCTION In north eastern Crawford County, north of Arma, US-69 spans Dry Branch Cox Creek. Two north-bound lanes are proposed east of the existing two-lane highway. A two-pier Prestressed K-4 Beam (PBMC) bridge with spans of 60’ – 85’ – 60’ will carry the two lanes with a 40.0-foot roadway. The geologic investigation performed during the spring of 2015 represents the best information available to the Kansas Department of Transportation.
GEOLOGIC FOUNDATION MATERIAL MANTLE The Mantle is all the material overlying bedrock. Along the banks of the stream, near both Abutments, up to boulder size limestone rubble and rip rap is present with silty clay fill material. The thickness of the rubble zone varies from 1.4 feet to 8.3 feet. A thin layer of topsoil overlies the rubble material at Abutment #1. Underlying the rubble the Mantle consists of light brown, soft, silty clay fill material and reddish brown to brown silty clay of alluvial origin. Total thickness of the Mantle at the Abutments is 20.3 feet to 23.8 feet. At the Pier locations of the proposed structure, the Mantle consists of approximately 4.1 feet to 6.3 feet of alluvial silty clays. Limestone boulders and rip rap may be within the upper 1.5 feet of the Mantle at Pier #2.
BEDROCK Middle Pennsylvanian Series Desmoinesian Stage Cherokee Group Cabaniss Formation Underlying the Mantle at the project location is the Pennsylvanian Cabaniss Formation. The Cabaniss Formation consists of dark gray to black shales, coals, underclays, sandstones, and limestone. The laterally persistent Verdigris Limestone Member exists at depth beneath the dominant shale lithology. In descending order, the bedrock units observed includes the upper shales of the Cabaniss Formation, the Bevier Coal bed, the Verdigris Limestone Member, and black shales. At the Mantle/Bedrock Contact, there is up to 2.2 feet of slightly weathered, grayish brown, clayey shale. The weathered shale grades to a dark gray, medium hard shale. This shale is homogenous in the upper portion and becomes laminated with depth. The laminated shale grades to black, carbonaceous, and limey shale with zones containing fossils. Thin zones of hard siltstone, less than 0.1 feet thick, are interbedded in the black shale. The upper shale of the Cabaniss Formation has an approximate thickness of 33.3 feet at the project site.
Underlying the black shale is the Bevier Coal Bed. The Bevier is 1.3 feet in thickness with an associated soft, gray, underclay which is 0.5 feet thick. Calcite, from secondary mineralization is found in the coal. Directly underlying the underclay is the Verdigris Limestone Member. Verdigris Limestone Member The Verdigris Limestone Member is an important marker bed in the Cabaniss Formation. The Verdigris Limestone Member is very hard, dense, light to dark gray, and slightly fossiliferous. Thickness of the Verdigris is 1.7 feet at the proposed structure. Underlying the Verdigris Limestone is black shale of the Cabaniss Formation. This shale is limey and contains numerous fossils and fossil fragments. Total thickness of the Cabaniss Formation was not found during this investigation but literature states it can be up to 220 feet.
ROCK MASS RATING The Rock Mass Rating (RMR) is used for classifying rock mass quality. There are five properties or conditions which are used to formulate the RMR. They are as follows: 1.) 2.) 3.) 4.) 5.)
Compressive strength of intact rock Rock Quality Determination (RQD) values Joint spacing Condition of the joints Groundwater conditions
The sum of the value ratings minus the joint orientation rating produces the RMR for the specific rock or rock mass. The tables that follow show the RMR ratings for each geologic unit observed at this proposed bridge location. Cabaniss Formation
Parameter Uniaxial Compressive Strength Drill Core Quality RQD Spacing of Joints Condition of Joints General Groundwater Conditions Minus Joint Orientation Adjustment RMR Relative Rating Class No. Description
Measured Values
Relative Rating
187.5 ksf 83% 3’ to 10’ Slight rough, Separation
