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Home My WebLink AboutUntitled oj t. Mu FouNDATION, SLAB,AND PAVEIVIENT DISCUSSION ANI) RECOMMENDATIONS Various foundation types have been considered for support of the proposed structure. Two requiremenn, muss ne met in the design of Raindarions First, the applied bearine stress must be less than thc ultimate hearin capacitv of foundation soils to maintain stability. Second, total and differential settlement must Oct exceed an amount that will produce on advefSC behavior of the superstructure. Allowable settlement k usually exceeded before bearing capacity considerations become important: thus, allowable bearing pressure is normally controlled by settlement considerations. Considering subsurface conditions and the proposed construction, it is recommended that the structure be founded upon conventional spread footings and continuous wall footings. Total settlements should not exceed 1 inch if the following design and construction recommendations are observed, Foundation Design Recommendations Based on data obtained from the site and test results from various laboratory tests performed. MU recommends following guidelines for the net allowable soils bearing capacity': Soil Bearing Capacity Footings must bear on competent, undisturbed, 2,000 lbs,112 native cemented sandy silt soils or compacted Not Required for structural 1111. ExistMg lean clay soils and fill Native Soil A 1/3 increase is allowable materials must be completely removed from for short-term loading, below foundation elements. Excavation depths . Li nt tor Structural VellILIE is cilIK ,U se SHIP_ ranging from 2.6 to 2.7 feet bgs should be " events or designed kvind anticipated to expose proper bearing soils.- speeds. fit will be rettuired for MTIpersonnel to veri the bearinusoBsultabIlity lot each structure at the time of construction, t2c,..nencling on the time of year constnietion takes plice,,the subgrade soils may be unstable because cf high moistme contents,_ unstable conditions are encountered over-excavation and replacement with,gramilar structural (ill antror use of cteotextiles inav be rDjuirect The following sliding frictional coefficient values should he used: 1) 0,35 for footings bearing on native sandy silt (ML) sediments and 2) 0.15 for footings bearing on granular structural fill. A passive lateral earth pressure of 335 pounds per square foot (osf should be used for sandy silt t1\41,) soils. For compacted sandy gravel fill, a passive lateral earth pressure of 496 psf should be used. Footings should be pitiportioncd to meet either the stated soil hearing eapaeityor the 2012 IBC minlinnut requirements. Total settlement should be limited to approximately I Mull, and differential settlement should be limited to approximately I!; inch. Objectionable soil types encountered at Me bottom rti' loonsa csanntations shonld he reminand and r("pl:ICO,C1 tvith sli' u till I NeeStikt:r). II -0 4 Yr islhat ,11101)LITItered iii tile tOCIOM.2. Sa,gracic ,,-Iver-excavation and backiiiiiip4 iii Irl,, t,mil elk Is uejil Cilift:Ttf' ) MCIVCrikIlt di it iiin (WCIIF heuute I,f ‘',4'1„!1,t0)!-: and nioisturt.' onten hIll rocornmenc.k continuous foonny:,; itoL.; II) of 24 liNSPECTIK_IN to 1I'L IUas ;:,s possible. Foi frost proh-xtioa. he bottom of e.xicirnal loot ricsShoijid Ur:. k rifliShH V1001". Slai)-1.)1i-GlAile .\ thai iiei of 1.111(.:0111110Pd fill, which contained sonie construction debris, was eneountei cd thod) locations, NTfl recommends that these fill soils bc excavated.iLasufficiera depthlinexposi.Leaativetent, nativesoils, M)11 personnel must be present durinl,,,excavation_toldentlivjhese materials, Native day soils are moderately plastic and will be susceptible to shrink/swell movements associated \vial moisture changes. Areas of the site within the proposed structures should be excavated to sufficient depths to expose lean clay. The clay soils should be scarified to a depth of 6 inches and re-conTacted between 92 percent and 98 percent of the maximum density as determined by ASTM D69$. The moisture content diould range from 1 to 4 percentage points above optimum. Structural fill should be placed as soon as possible after re-compaction of cloy soils in order to limit moisture loss within the upper clays. Ground surfaces should be sloped away from structures at a minimum of 5 percent for a distance of 10 feet to provide positive drainage of surface kvater away from buildings. Grading must be provided and maintained following construction. (..)rganie, loose, or obviously compressive materials must be removed prior to placement otconcrete floors or floor-sumorting lift In addition, the remaining suhgrade should he treated in accordance with presented in the Earthwork section. Areas of excessive yielding should be excavated and haelc1111;2d with structural till. HI used to increase the elevation of the floor slab should meet requirements detailed in tin: Structural Fill section. fill materials must he compacted to a minimum 95 percent of maximum densit determined by ASTM 1)1557. free-draining. granular Mal (drainage fill course) should be provided below slabs-on-grade. This should he a minimum of 4 inches in thickness and properly compacted. The mat should consist olio sand and ral. mixture, complying with Idaho Standards for Public Works Construction (1SPWC) specifications for ('hype 1) crushed aggregate. A moisture-retarder should be placed beneath floor slabs to minimize potential ground moisture effects on moisture-sensitive floor coverings. The moisture-retarder should be at least 15-mil in thickness and have a permeanec of less than 0.01 US perms as determined by AS] N1 F96. Placement ()Ill the moisture-retarder will require special consideration with regard to effects on the slab-on-grade and should adhere to recommendations outlined in the .ACil 302.1R and ASTM F1745 publications. The gianulai i at should be compacted to no less than 95 percent of maximum density as determined by AS]'\l1)1557, 1..lnon request. MTI can provide further consultation regarding installation. Recommended Pavement Sections has inade assumptions for traffic loading variables based on [lie character of the proposed construi„tien Ilk client shah revievv and understand these assumptions to make sure thev reflect intended use iind In; ii injpovements both now and in the Ritmo. Rased on c7\-pericfncc with soils in the region. a tic ) value 01.3 inrs heen assumed for near-surlace lean clav soils on site he nnnimum thickness requirc.'ments tor assured pavement function. 1.)cpending on !tit,' conditions, adi,ittioi,:d sod proparaj,ion, may Nc roquired to support euns.truction Nuifinient, Horl ift' Soft Sithgrialc Soils or.rTiif I,%:51,' v t Init.;Pt ff X.s;:'.',"-:i.'ff...i"•'tt L. Pi\til;',PECT$ON i....i....,,i,iii.J . ) .J .;:_f I'•'1earble j'avtment Sedi(ne Inc American Association of Suitt" IIILtand Transportation Officials f A.A.,f1 I I &sign fircthod frx... t"oen used to calculate the following pavement sections. Calculation sheets provided in the Aprierldk indicate the soils ennstant, traffic lottding. traffic projections and nifiterial constants intoo tit c ficonfte the pavehient sections MTI recommends that materials used in the construction rat asphaltic" ci'iriCreti.: 1Tia.\CITIQIiL, meet requirements of the 1SPAVC Standard Specification for Ifighway Construction, Confarnenop of Lif pavement section should be in accordance with these specifications and should adhere to guideline recommended in the section on Construction Considerations, AASIIITO Flexible Pavement S eeifieations i Asphaltic Concrete 2.5 Inches 3.0 Inches Crushed Aggregate Base 4.0 Inches 6.0 Inches i I, i -- - - - Structural Subbase 12.0 Inches 14.0 Inches Coinpacted Subgradc 95% of ASTM 1)608 .... 95% of AS1'M D698 • i It will h.:: requitc(I ha Mil_personnel to verify subgrade coinvetenev at the time of construction, Asphaltic ConcreteAsphalt mix design shall meet the requirements of ISPWC,, Section 810 Class III plant in Materials shall he placed in accordance with ISPWC Standard Specifications icr ilhe;t:hwtat:,, (..:onstmetion. ,Aggregate Base: Material complying with ISPWC Standards tor Crushed Aggregate Materials. Structural Subbase: Material should comply with the requirements detailed in the Structural PM section of illy, report except that the maximum material diameter Is no more than /2 the component thickness. Common Pavement Section Construction Issues The subgrade upon which above pavement sections arc to be constructed n-iusi be properly stripped. Mspected, and proof-rolled. Proof rolling of subgrade soils should be accomplished using a heavy rubber - tired. fully loaded, itmdem-axle dump truck or equivalent Verification of snbgrade contpelenee by M1 I personnel at the time of construction is required. Fill materials on the site must demonstrate the indicated compaction prior to placing material in support of the pavement section. MTI anticipates that 1'4)K orncnt areas will be subjected to moderate traffic. Dependent upon the time of year construction takes place, shallow native lean clay soils may tend to pump and rut during compaction, Clay and silt soils near and above optimum moisture contents may tend to pump. Pumping or soli areas must be removed and replaced with structural till. I ill material and aggre:gf tics iii support of the pavement section must be compacted to no less thim (lif-, rcit..Liii ci.thc* maximum dry dontity a", tleturnined by ASTM 1)698 kir liCNible IN:WelIR -OS ..,I1R1 f-f.: ,\S I N.1 rif•T,s7 is fr rigid pavements. Ili: material placed as a paver/rent section component cannot he tested by ascal coalphn ion testing rneihods. then compaction of that material must be approved by ()laser,ed grief rolling fylinf a (lcitek.Hons from proofrolliiv lOr rIt'sible pavements nre L'i WO\a bL. ')t'llyel ion', from pool it hum . (11' 1,-.:1% ::..'.710.111 Supp4)0 Pours‘—t. thoitkl m t h vitmaint, uqccratqc,