3000 ROCKEFELLER AVE PARKING GARAGE 2018-01-02 MF Import

J:-i-1•'J'�;�,•:%1'''li? SOi�.INt^_.. maintain stability in fill soils, and thc "st.md up" time and depth for cach level of excavation may bc limi�ed. � 1Vith every excavation in soil, both clustic and inclastic ground displacements will occur bchind ihe carth support system as a result of the changcs in stresscs �aithin thc suRounding soil � mass. Thc displaccmcnt magniwdcs arc dcpcndent on thc stress-deformation properties of the soil; design laleral earth pressures; the conf iguration, stages, and depth of excavation; ��all stiffness; spacing of soil nuils; groundwater conditions; and the care and skill with which the � cxcavation work is accomplishcd. Thc following scction providcs a gencral soil nail dcscription. �Vc will p: ��idc soil nail wall shoring plans scparatcly. (O.A 2 Description of Soil Nailin}; Soil nailing consists of drilling :ind ��routing a scrics of stccl bars or "nails" hchind thc e�a��ation facc and then covering the face �aith reinfbrced shotcrete. The placement of re�ati��ely closely spaced stecl nails in the retained soil mass increases the shear resistance o( the soil against rotational sliding, incrcases thc tensile strength of the soil bchind potential slip surfaccs, and modcr:ucly inrr�ascs shcar resislancc at a potcntial slip surfacc duc ro thc bcnding stiffncss of thc nails. Soil nailing is mast cffcctivc in dcnsc, gr:mul;ir suils and stiff, lo�� plasticity, finc-graincd soils. Soil nailing may not be cost-effective in loose granular soils, soft cohesi��e soils, highly plastic clays, or whcrc uncontrollcd groundwatcr c�ists abovc thc botrom of thc cxcavation. In ��ener:il, cxca��ation faccs must bc ablc to stand unsupported for 2�4 to d3 hours in ordcr for soil nailing to bc fcasiblc. Groundwatcr is anticipatcd to bc above thc bottom of thc cxcavation at ihc Administration Garagc; thcrcforc, temporary dcwatcrina mcasures ��ould havc to bc implemcntcd piior to shoiing ��all construction to control groundwatcr and maintain a dry escavation face. Temporary dewatcring is discussed later in this report. Soil nails consist of stccl bars (typically 3/4 to I-3/S-inch diamctcr), which arc installcd by h'cmic grouting thc nail into a prcdiillcd holc. Soil nails arc locatcd in a squarc or rcctangular grid pattern and are typically installed at an inclination angle of 15 degrecs from horizontaL The construction scqucnce of a soil nail wall generally includcs three steps: 1) staged caca��ation, 2) nail inst:�llation and scicct nail tcsting, and 3) drainagc and facing construction. This scqucncc is rcpcatcd until the c�ca��ation and shrning is cotnplctc. _ i-i-ovol� ro�s.0 v,, i, un 2 l-1-096=1-� -00� li