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From page 66... ... 66 C H A P T E R 5 In Situ Testing of Soil and Rock Introduction Because the vast body of natural soil and rock at the project construction site will serve as the primary bearing medium for new bridges, highways, cut slopes, walls, and embankments, in situ geotechnical tests provide valuable information concerning the field strength, deformation properties, stress state, and hydraulic conductivity of the underlying geomaterials. The term in situ is derived from Latin meaning in its original position" and refers to the testing of geomaterials while they remain in the ground, in contrast to the more traditional approach of taking samples from boreholes and transporting them to the laboratory for testing. Read the entire page →
From page 67... ... 67 Source: Paul Mayne Figure 5-1. Selection of in situ tests for geotechnical site characterization Borehole Test Methods Borehole-type field tests can be conducted in open borings, beneath borehole casings, or below the bottoms of HSAs, depending upon the soil conditions and drilling methods used. Read the entire page →
From page 68... ... 68 Source: Paul Mayne Figure 5-2. SPT setup and procedures The testing procedures for the SPT are found in AASHTO T 206 (ASTM D1586) Read the entire page →
From page 69... ... 69 Source: Paul Mayne (based on data from VTrans) Figure 5-3. Read the entire page →
From page 70... ... 70 An example of the large differences in N-values obtained using a safety hammer and automatic hammer in two side-by-side borings advanced at the national geotechnical experimentation site at Northwestern University can be seen in Figure 5-4. Here, the SPTs are conducted in a fine sand layer that extends to a depth of approximately 22 ft (6.7 m) Read the entire page →
From page 71... ... 71 Energy Ratio (percent) Automatic Hammer System Mean Standard Deviation Location or Agency CME 850 79 ± 2 Tennessee CME 45c Track 80.6 ± 3.9 VTrans CME 45 80.7 ± 10.1 Florida DOT CME 45c Track 81.1 ± 5.8 VTrans CME 85 81.2 ± 3.9 Florida DOT CME 75 w/ AW-J rods 81.4 ± 4.7 ASCE/WA CME 75 83.1 ± 5.1 Florida DOT CME 75 Track 84 ± 5.3 VTrans CME 55 Track 85 ± 4.9 VTrans CME 750 86.6 ± 6.2 Utah DOT CME 55 Track 87.4 ± 5.4 VTrans Mobile B-57 88 ± 3 Tennessee Mobile B-57 93 ± 3 Tennessee CME 75 rig 94.6 ± 2.1 Utah DOT Sources: ASCE/WA (Batchelor et al. Read the entire page →
From page 72... ... 72 Factor Influencing Variable Field Case Factor Values CR Drill rod length, L (ft) L > 33 20 < L< 33 13 < L < 20 10 < L < 13 L < 10 CR = 1.00 CR = 0.95 CR = 0.85 CR = 0.80 CR = 0.75 Source: modified from Skempton (1986) Read the entire page →
From page 73... ... 73 Source: Paul Mayne Figure 5-5. VST or field van for clays and silts The standard vane is rectangular with a blade width (D) Read the entire page →
From page 74... ... 74 Source: Paul Mayne Figure 5-6. Limit equilibrium solutions for calculating undrained shear strength of rectangular and tapered vanes Modern field vanes employ downhole electronic torque meters and rheometers to measure moment and rotation of the blades (Peuchen and Mayne 2007) Read the entire page →
From page 75... ... 75 Example results of EVST in soft clay for a bridge and embankment crossing in Idaho are presented in Figure 5-8. The peak values of undrained shear strength are seen on the right side of the figure, averaging around = 777 psf (37.2 kPa) Read the entire page →
From page 76... ... 76 Source: Paul Mayne Figure 5-9. Basic components and procedures of the PMT Figure 5-10 shows an example of a pressure vs. Read the entire page →
From page 77... ... 77 The lift-off pressure is considered to relate to the geostatic horizontal total stress (σh0) and may be used to estimate the lateral stress coefficient, = ⁄ , where the effective horizontal stress = − . Read the entire page →
From page 78... ... 78 Direct-Push In Situ Test Methods for Soils Several statically pushed in situ testing devices have been developed to facilitate direct measurements in soils and expedite field testing times. These direct-push methods often employ large (22.5 tons) Read the entire page →
From page 79... ... 79 Source: Paul Mayne Figure 5-11. Basic setup and equipment for (electric) Read the entire page →
From page 80... ... 80 Type of CPT Acronym Measurements Taken Applications Seismic Piezocone Test SCPTu Same as CPTu with downhole shear waves (Vs) Read the entire page →
From page 81... ... 81 Example results for a CPTu are presented in Figure 5-13. Read the entire page →
From page 82... ... 82 most clays FR is greater than 4 percent. In highly organic clays and peats, FR is greater than 6 percent. Read the entire page →
From page 83... ... 83 to penetration resistances. The general setup and procedures of the test (ASTM D5778 and D7400) Read the entire page →
From page 84... ... 84 Source: ConeTec Figure 5-16. Example SCPTu soundings in sediment Continuous-interval shear wave measurements can be obtained with Vs readings as frequent as the cone penetrometer values, on the order of several centimeters (Ku et al. Read the entire page →
From page 85... ... 85 Source: Mayne and Woeller (2015) Figure 5-17. Read the entire page →
From page 86... ... 86 Source: Paul Mayne Figure 5-18. DMT procedures and measurement readings Once the DMT data is processed, the field-measured A and B readings are corrected for membrane stiffness in air and renamed: p0 = contact pressure and p1 = expansion pressure (see Fig. Read the entire page →
From page 87... ... 87 Source: ConeTec Figure 5-19. Example DMT measured pressure profiles Source: ConeTec Figure 5-20. Read the entire page →
From page 88... ... 88 Campanella and Robertson (1991) Read the entire page →
From page 89... ... 89 Source: data from Kavur et al. Read the entire page →
From page 90... ... 90 Source: Paul Mayne Figure 5-22. Cross section of flat jack setup per ASTM D4729 5.4.3 Rock Dilatometer A rock dilatometer test is used to evaluate rock mass stiffness. Read the entire page →
From page 91... ... 91 Source: Dick Handy, Handy Geotechnical Equipment Figure 5-23. Rock borehole shear test in sandstone 5.4.6 Measurements for Rock Discontinuities Optical and acoustic televiewers provide a continuous, 360° view of the borehole wall that allows rock mass discontinuities to be identified and characterized. Read the entire page →
From page 92... ... 92 Chapter 5 References Batchelor, C., G Goble, J Read the entire page →
From page 93... ... 93 Robertson, P.K. Read the entire page →

From page 66...

... 66 C H A P T E R 5 In Situ Testing of Soil and Rock Introduction Because the vast body of natural soil and rock at the project construction site will serve as the primary bearing medium for new bridges, highways, cut slopes, walls, and embankments, in situ geotechnical tests provide valuable information concerning the field strength, deformation properties, stress state, and hydraulic conductivity of the underlying geomaterials. The term in situ is derived from Latin meaning in its original position" and refers to the testing of geomaterials while they remain in the ground, in contrast to the more traditional approach of taking samples from boreholes and transporting them to the laboratory for testing.