501 SECTION 626 RETAINING WALL SYSTEMS
626.1 -DESCRIPTION : This work shall consist of furnishing the design, wall construction plans, materials, and construction of cast -in-place reinforced concrete or Mechanically Stabilized Earth (MSE) walls in accordance with these specifications and in reasonably close conformity with the lines, grades, design, and dimensions shown in the plans.
626.2 -GENERAL : Unless specified otherwise in the contract documents the wall may be, a t the Contractor ’s option, any one of the wall systems on the approved source list corresponding to the applicable Pay Item; this list is posted on the MCS&T web page under the heading Approved Source/Product Listing. The Contractor shall indicate which wall system is to be constructed by the bid alternative chosen in the proposal. No change of the wall system indicated in the bid proposal shall be permitted after the bid opening unless approved by the Engineer. The wall design and detail plans for con struction shall be submitted to the Engineer for approval. The time required for preparation and review of these submittals shall be charged to the allowable contract time. Delays caused by untimely submittals or insufficient data will not be considered justification for time extensions. No additional compensation will be made for any additional material, equipment, or other items found necessary to comply with the project specifications as a result of the Engineer ’s review. The proposed wall design shall be compatible with the Contractor ’s proposed method of construction, and shall be compatible with any method of construction shown in the plans. The Division does not assume nor warrant any wall system ’s compatibility with any particular cons truction methods.
626.3 -DESIGN CRITERIA : 626.3.1 -General: The size of all structural elements shall be determined such that the design load stresses do not exceed the allowable stresses found in the AASHTO LRFD Bridge Design Specifications, latest edition. Analysis of external stability of the in -place retaini ng wall system will be the responsibility of the Division. Any staged or temporary construction affecting wall stability shall be the responsibility of the Contractor. The parapets on any portion of the retaining walls as shown in the plans shall be desi gned to resist traffic loads in accordance with the AASHTO LRFD Bridge Design Specifications, latest edition.
626.3.2 -Mechanically Stabilized Earth: The design for the MSE wall shall consider the internal stability of the wall mass. The design shall co nform to the requirements found in AASHTO LRFD Bridge Design Specifications, latest edition. External loads, which affect the internal stability such as those, applied through piling, bridge footings, temporary construction, etc. shall be accounted for i n the design. A design life of 100 years shall be used throughout the design. The factor of safety for pullout resistance shall not be less than 1.50 based on pullout resistance at ¾ inch deflection. The allowable bearing pressure under the stabilized mass shall be as shown in the plans. The minimum length of the soil reinforcing system, as measured from the back of the front
502 face to the end at the back of the soil stabilized mass, shall be as shown in plans, and shall be the same from top to bottom of the wall at any cross section. All appurtenances behind, in front of, under, mounted upon, or passing through the wall such as drainage structures, utilities, or other items shown in the plans must be accounted for in the design of the wall.
626.3.3 -Cast -in-Place Reinforced Concrete : When a Cast -in-Place Reinforced Concrete option is included in the plans the following shall be applicable. The information shown in the plans for the cast -in-place alternative is schematic; however, all dimensions show n in the plans shall be considered minimums. The allowable bearing pressure of the foundation soils, the unit weight of the retained soils, and the characteristics of the retained soils necessary for design purposes shall be as shown in the plans.
626.4 -SUBMITTALS : 626.4.1 -General: The Contractor shall submit complete design calculations, explanatory notes, and detail plans for the proposed wall system. The detail plans shall include all details, dimensions, quantities, and cross sections necessary to construct the wall and shall include but not be limited to the following items: A plan and elevation sheet or sheets for the wall which shall contain the following:
at all horizontal and vertical break points and at least every fifty ( 50) feet along the face of the wall, all steps in the footings or leveling pads, the original and final ground lines, the maximum b earing pressures, and the summary of quantities for each wall.
to the face of the wall at all changes in horizontal alignment and the centerline of any drainage struc ture or drainage pipe behind, passing through, or under the wall.
existing ground conditions and proposed grades.
for the elongation of the soil reinforcing during erection shall be shown for each different required height.
footings or leveling pads.
or passing through the wall such as drainage structures or utilities shall be clearly indicated.
Manuals on each project.
details for any required architectural treatments shall be shown incl uding:
liners, release agents, ties, and accessories. The release agent manufacturer shall certify that the products supplied comply with regulations controlling the use of volatile organic compounds (VOC ’s).
that visually affect the exposed concrete, including, but not limited to, general form
503 construction, jointing, specially formed joints or r eveals, and patterns of placement. The Engineer ’s review will be for general architectural applications and features only. Formwork design for structural stability and sufficiency is the Contractor ’s responsibility and shall not be submitted for the Engi neer's review.
sample facing element using the proposed formwork and facing materials in order to demonstrate the required finishes and textures. Actual construction of concrete shall not proceed until the Engineer has accepted the sample units.
At the time the detail plans are submitted for review, they shall be accompanied by design calculations and explanatory wall notes. These documents shall be legible and shall demonstrate that the design criteria have been met. Specified minimum factors of safety and the maximum soil pressure beneath the wall footing or earth stabilized mass shall be clearly indicated. The plans shall be prepared on reproducible sheets twenty -two ( 22) x thirty - four (34) inches including borders. Each sheet shall have a title block in the lower right hand corner. The title block shall include the sheet number of the drawing, name or designation of the wall, the state and federal project desi gnation, project name, fabricator and Contractor name. Design calculations and notes shall be prepared on sheets 8½ x 11 inches, and shall contain the project designation, wall designation, date of preparation, initials of designer and checker, and page n umber at the top of the page. The Detail Plans, Design Calculations, and Explanatory Notes shall be signed and stamped by a Professional Engineer registered in West Virginia and knowledgeable in the proposed alternative wall system. The initial submissi on shall include three sets of the detail plans, calculations, and notes. One set of notes and plans will be returned to the Contractor with any indicated corrections. When the plans and notes are stamped approved by the Engineer, the Contractor shall fu rnish the Engineer with the requested number of sets of prints and a Mylar set of the plans for distribution by the Division. The Contractor shall perform no work or ordering of materials for the structures until the Engineer has approved the submittal.
626.4.2 -Mechanically Stabilized Earth: The details and material specifications for the wall facing elements and incidental accessories shall be included with detail plans for approval by the Engineer. The designation as to the type of facing element, the length of the soil reinforcing systems, the distance along the face of the wall where changes in lengths of the soil reinforcing systems occur, and the limit of mesh, strip, or anchor shall be clearly shown in the plans. All wall facing elements shal l be detailed. The details shall show all dimensions necessary to construct the element, all reinforcing steel in the element, and the location of soil reinforcing system devices embedded in the elements.
626.4.3 -Cast -in-Place Reinforced Concrete : The plans for the cast -in-place wall shall contain a complete reinforcing bar schedule showing all bending details and bar marks. The plans shall also show the location of all construction joints, expansion joints, or other joints in the wall. All wall thic kness shall be shown and transition details at wall thickness changes.
626.5 -MATERIALS : 626.5.1 -Mechanically Stabilized Earth Components: The Contractor shall make arrangements to purchase the facing elements, reinforcing mesh or strips, attachment devices,
504 joint materials, and all other necessary components. Materials not conforming to this section of the specifications or from sources not listed in the contract documents shall not be used without written consent from the Engineer.
626.5.1.1 -Facing Elements: 626.5.1.1.1 -Reinforced Concrete Facing Elements: The facing elements shall be fabricated in accordance with Section 601 of the Spe cifications with the following exceptions and additions:
compressive strength of 4,000 psi at 28 days. All concrete shall have air entrainment of 7 % plus or minus 2.5 % with no o ther additives. Specified concrete properties are to be tested in accordance with applicable provision of made if the compressive strength test result is greater than or equal to, 4,000 psi. A Production Lot is defined as a group of panels that will be represented by a single compressive strength test result is greater than or equal to, 4,000 psi. A Production Lot is defined as a group of elements that will be represented by a single compressive strength sample and will consist of a single day’s production. A minimum of two cylinders shall be required for every compressive strength sample.
compressive stre ngth of 1,000 psi.
concrete surface for the front face shall have a Class 1 finish as define by Section
601.11and a uniform surface finish for the rear face. The rear face of the element
shall be screeded to eliminate open pockets of aggregate and surface distortions in excess of ¼ inch. The panels shall be cast on a flat area. The clevis loops, tie strip guide, or other galvanized devices shall not contact or be attached to the face element reinforcement steel.
clearly scribed on an unexposed face of each element.
dangers of chipping, discoloration, cracks, fractures, and excessive bending stresses. Elements in storage shall be supported in firm blocking to protect the element connection devices and the exposed exterior finish.
one (1) inch, except for coil and loop embeds which shall be 3/16 inch. All other dimensions within 3/16 inch.
two diagonals shall not exceed ½ inch.
over a length of five ( 5) feet shall not exceed ¼ inch. Surface defects on the texture d-finished surfaces measured over a length of five ( 5) feet shall not exceed 5/16 inch.