2414 BAKER AVE 2017-01-13 - Laserfiche WebLink

Tom Eiden June 21, 2010 JN 10114 Page 9 pcf. A safety factor of 1.2 or 1.5 should be applied to this value to account for temporary or permanent conditions, respectively. This soil pressure is valid only for a level excavation in front of the soldier pile; it acts on two times the grouted pile diameter. Cut slopes made in front of shoring walls significantly decrease the passive resistance. This includes temporary cuts necessary to install internal braces or rakers. The minimum embedment below the floor of the excavation for cantilever soldier piles should be equal to the height of the "stick- up.., The above values assume that the excavation is level in front of the soldier pile and that the bottom of the pile is embedded a minimum of 10 feet below the floor of the excavation. For the pile end-bearing to be appropriate, the bottom of the drilled holes must be cleaned of loosened soil. The shoring contractor should be made aware of this, as it may affect their installation procedures. The concrete surrounding the embedded portion of the pile must have sufficient bond and strength to transfer the vertical load from the steel section through the concrete into the soil. U/tra-B/ock Shoring If an easement from the adjacent owner to the north and the city to the west can be obtained to ensure that no automobiles are driven/parked adjacent within 10 feet of the back of the wall and that some minor amounts of the cut can be potentially extended over the property lines to the north during construction of the block walls, then a temporary Ultra-block wall may be constructed along the northern and western sides of the proposed garage for temporary shoring. Due to the limited area to the west, the temporary cuts would likely need to be extended into the alley and a por�ion of the alley closed to traffic. If the easement agreements cannot be obtained, then temporary soldier pile shoring is recommended in these areas. Cuts of up to a 7-foot vertical exposed height may be temporarily supported by Ultra-block shoring. An Ultra block is a precast 2.5-foot-square concrete block with a 5-foot length. The blocks can be stacked using an integral ridge along the top of the block that fits a like indentation in the bottom of the blocks above. The blocks should be stacked in a staggered brickwork pattern such that each block above interlocks with two blocks below. This may require the use of half-width blocks. The blocks may be stacked with no batter in this application, but the ends of the wall shouid be "returned" into the excavation to brace the corners and offer additional wall stability. The base of the block wall should rest on der�se native soils and the base block should be buried at least 6 inches below the bottom of excavation grade. The annular space behind the blocks should be filled with clean crushed rock (i.e. 2-inch ballast) for drainage. The excavation at the face of the base of the blocks (backfill of the embedded `key' below the bottom of excavation) should be backfilled with compacted crushed rock. Temporary vertical cuts will be necessary to install the biocks. We recommend that all of the materials for constructing the wall (blocks and rock) be onsite prior to the excavation for the wall. The wall should be constructed in segments (on the order of 10 feet long) with the blocks being stacked and backfilled immediately after excavation is complete. No excavated sections should be left open overnight. This "build as you go" technique will minimize the exposure of the adjacent soils to sloughing. A 1:1 (Horizontal:Vertical) slope above the block may be established with the backfill rock. An Ultra Block Wall Detail is attached to this letter as Plate 3. EXCAVATIOIV AND SHORING MONITORING As with any shoring system, there is a potential risk of greater-than-anticipated movement of the shoring and the ground outside of the excavation. This can translate into noticeable damage of GEOTECH CONSULTANTS, INC.