3003 W CASINO RD BLDG 45-12 2016-10-20

777X Static Test Building I 9 ■ For planning purposes, use allowable capacities for individual and grouped 8-inch-diameter micropiles in tension or compression of 8 kips per foot of pile within the glacial till bearing layer. Neglect micropile capacity above the bearing layer. ■ For 8-inch diameter micropiles installed in groups,space the piles with a minimum of 4 times the pile diameter, 5D, (i.e., 32 inches center-to-center). ■ Neglect axial capacity above the bearing layer. ■ Use a top-of-bearing-layer elevation based on the information provided in Figure 2. ■ Embed all micropiles a minimum of 15 feet into the bearing layer. ■ Allow Hart Crowser to review the final foundation plan to calculate settlement response after final structural loads and layouts have been established. We estimate that total post-construction settlement of micro pile-supported structural elements will not exceed 1 inch in compression or 1.5 inches in tension. These estimates will be verified or adjusted based on the pre-construction verification tests. Differential displacement between adjacent micropiles could approach one-half of the actual total displacement. ■ Require a verification test(to 200 percent of the design load)on two adjacent non-production, "sacrificial" micropiles following standard procedures and criteria (FHWA 2005) before construction of the production piles. This test is intended to ensure that the design capacities can be achieved with the soil and construction equipment/methods used by the contractor at the site. Space the verification tests at the planned group spacing(i.e., 32 inches center-to-center)to evaluate pile group effects. ■ Require proof tests (to 160 percent of the design load)on 5 percent of the production piles with at least one proof test per substructure unit. GEOTECHNICAL RECOMMENDATIONS FOR CONSTRUCTION This section presents our recommendations and conclusions for geotechnical aspects of construction. Based on our explorations and experience in the area, cobbles and boulders may be present within the Glacial Till unit. Such large materials could make drilling and/or excavation difficult. Therefore,the contractor should be prepared to deal with large obstructions. In addition,the glacial till unit may also contain relatively clean sand and/or gravel zones,where groundwater may accumulate and be more prone to caving when exposed in a vertical face or encountered in a drilled hole. Glacial till density and the possible presence of large cobbles and boulders may also make drilling solider piles or micropiles difficult. Provisions should be made in contract documents to account for the possibility of these conditions. MrV AN 19106-01 HAff 0?0wSME May 29,2015