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HomeMy WebLinkAboutDRB150443_FIELD CONSTRUCTION- STONE TERRA_1443109620.pdfFIELD CONSTRUCTION MANUAL- STONE TERRA EXCAVATION Confirm location and elevation of walls. Width of excavation should allow for width of wall base and drainpipe. Note: all excavation should follow applicable WISHA or OSHA guidelines. If the wall steps up one block in height, the base blocks should be installed at the lowest level in order to establish grade and face location of the second level. BASE PREPARATION Consult engineer's wall design for a base material specification including type, width, depth and compaction. It is recommended to start at lowest wall level. Locate the front face of the wall and run a string line one-inch in front of the face - two-inches above the base. Make sure the base material is well compacted. Test if necessary. After compacting, screed off base material, fill in low spots, and screed again. Repeat procedure as necessary to achieve firm, compacted base. Do not disturb string line. It is best to prepare the entire base before setting the blocks. SETTING BLOCKS Before placing blocks, make sure the top and bottom surfaces of the respective blocks are clean. At one end of the wall, or at one end of the lowest base elevation, start the wall. At the start of the wall, mark a line perpendicular to the face of the wall. This line will help place the first block square to the wall face. Place the first block one inch from the string line. Set the next block beside the first block, taking care to align the face. GEOGRID MSE walls are walls that have geogrid material sandwiched between each row of block. A maximum of two courses can be built before the wall must be backfilled. Start with the base course and lay the specified geogrid over the keyway of the blocks so that the grid reaches the face of the block, and covers the male keyway. Place the upper block over the grid, locking it into place. Once the wall is built to two blocks high, stop the block stacking process and begin backfilling the wall. Make sure drainpipe, filter fabric, and drain mats (if required) are installed before backfilling. Flip the geogrid forward over the face of the wall to get it out of the way and fill the wall with the specified backfill material, so that the material is level with the top of the first course of block. Compact backfill material to specified compaction. Flip the geogrid back over the wall so that it covers the compacted backfill material. The geogrid should lay level over the compacted backfill (not at any discernable angle). Pull the grid taut and stake it to hold it in place as you begin to backfill over it. Fill to the top of the second course of blocks, compacting as necessary. When finished, you will have two courses of block with a layer of grid between, a 4’ high wall, and you will be ready for the next layer of grid.. Continue building in 4’ lifts, alternating grid and block, until maximum wall height is reached. NOTE: you will now being laying down two layers of grid for every two layers of block. NOTE: Take care to align the grid properly to the wall so that the strength direction of the grid is perpendicular to the wall face. Generally, the grid will be rolled back from the blocks (behind the face of the wall) and cut to the proper reinforcement length. In other words, grid cannot be rolled along the length of the wall, parallel to the wall face. Check with your grid manufacturer if you are unsure about proper grid installation. Do not set any more than 25-ft to 30-ft of blocks along the length of base starting on the second row. EQUIPMENT FOR PLACING BLOCKS A backhoe is the ideal piece of equipment for setting blocks. A wire rigging or chain with swivel hooks, OSHA approved and rated for the weight of the blocks, can be attached to the backhoe and used for lifting and moving blocks. SAFETY FACTORS 1. Never stand underneath a block. 2. Avoid getting any part of the body between pinch points while installing blocks (either between two blocks or between a block and the open excavation). 3. Always inspect rigging for lifting the block. replace all worn or broken parts. DO NOT USE INFERIOR, INADEQUATE OR UNAPPROVED EQUIPMENT. USEFUL TOOLS 1. Transit- to lay out a level base. 2. Shovels and rakes- for use by the base prep person. 3. A broom- to clean the keyways before placing the next layer. 4. One or more 5 foot pry bars- for jostling the blocks into position. 5. A 4’ level FINAL LEVELING OF THE WALL Imperfect or disturbed bases can cause a wall to not run straight or level. It is recommended to shim (asphalt shingle) wall if necessary or place a 4X6 on top of the wall at the high points and pound down with the excavator bucket.