1.0 GENERAL This design guide presents guidance for planning, performing, and reporting soil investigations. All information presented within this document is summarized from Unified Facilities Criteria (UFC) and Engineering Manuals (EM). It is not a comprehensive textbook on soil sampling; the treatment of this subject cannot be substituted for actual experience. Rather, it is a summary of commonly accepted soil sampling practices and procedures which are intended to assist geotechnical personnel performing actual field operations or those personnel functioning as contracting officers' representatives. Soils investigations for USACE-AED projects are intended to provide the design engineer various design parameters including: a. Revealing adverse subsurface conditions that could lead to construction difficulties, excessive maintenance, or failure of the structure b. Depth required for satisfactory bearing material for foundations c. Bearing capacity of soil for building or other structural foundations d. Potential range of settlements of buildings e. Allowable California Bearing Ratio (CBR) for road bed design f. Optimum moisture content at optimum compaction g. Depth of groundwater for dewatering and buoyancy design considerations h. Minimum embankment side slope and benching required for cuts and fills i. Erosion protection requirements j. Expected long term settlements of high embankments and placement and compaction procedures to minimize adverse impact to project functions k. Active and passive pressures for retaining walls and revetments l. Internal friction angles and cohesive strengths of soil for analyses m. Water-soluble sulfate in soil (ASTM C 1580). Percolation test results (U.S. Environmental Protection Agency guidance is available from AED). Additional design parameters may be requested in the contract technical requirements. This design guide is intended to provide contractors information on the expected investigations and methods required for geotechnical reports for USACE-AED projects. It should provide USACE-AED with standardized sets of information from which a reliable data base can be maintained for future use in project development. It is intended to eliminate submittal of information that USACE neither requests in the contract technical requirements nor uses in its evaluation of project designs; thereby also reducing costs for supplying this information from contractors. Insufficient geotechnical investigations, faulty interpretation of results, or failure to portray results in a clearly understandable manner may contribute to inappropriate designs, delays in construction schedules, costly construction modifications, use of substandard borrow material, environmental damage to the site, post construction remedial work, and even failure of a structure and subsequent litigation.
Step 1: Plot graphs See Fig. E5.5. Step 2: Determine whether the sand is dense or loose. The sand appears to be dense-it shows a peak horizontal force and dilated. Step 3: Extract the rcq uired values. Cross-sectional orca of sample: A - 10 x 10 - 100 cm1 to··l m1 (cl) ,. = ( P,)p - IOOS X 10 3 = 100.5 kP P A 10 2 a (c2) ,. = (P.)a - 758 N X 10-J = 75 8 kPa "' A 10-1 . (c3) a = tan 1(- z) - tan_1(0 .1) = 7 I" 1200 1000 g eoo A 600 Peo• Crlt ll.L I V,_ T r\ : - I I I ii 400 % I 'I I I I: llcro.IOtllal dsplottmtl'l (.....) lol 0.00,0._....,20:::-_...;•'---T--=----:;lr-0 -;12 I-0.10 j -0.20 § -0.30 1--+--...., -0. 0 1--+-- -0.50 1--+-- > -060 -0.70 '-----'--- ..:. .:...._ , FIGURE ES.S
Detennine the following: (a) ci>:. (b) <1>;nt venical forces of200 N aod 400 N for sample B (c) The dilation angle at vertical forces of 200 N and 400 N for sample B Strategy To obtain the desired values, it is best to plot a graph of vertical force venu.s horizontal force. Solution 5.3 Step 1: Plot a g1'3pb of the verllcal forces venus failure horizontal forces for each sample.See Fig. E5.3. Slcp 2: Extract cf>;.. All the plotted points for sample A fall on a straight line through the origin. Sample A is a nondilatant soil, possibly a loose sand or n normally consolidated clay.The effective friclion angle is <1>:. 30'. Step 3: Determine q,;. The horizontal forces at 200 N and 400 N for sample B do not lie on the straight line correspondang to 4>:.- Therefore.each of these forces has a c >; associated with it. (o>;),00 N • tJJn- G ) e 41.2" Co>;).,. N • tan-•(!:)= 31.8" Step 4: Determine a,. a,- ;- (u),..,. • 41.2 - 30 = 11.2' (a)4110 ,. • 31.8 - 30 = 1.8" Note that as the normal force mcreases a,decreases. 500 .--- . - - - - .,....-.,.--, 1 0 X O0 200 "00 600 800 'twta...l ftn:l! (H)