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From page 130... ... 130 C H A P T E R 8 Laboratory Testing of Soil and Rock Introduction Laboratory tests on soil and rock can be used to model existing in situ conditions as well as conditions that will exist at different stages of project development because the tests can systematically characterize the behavior of soil and rock in a controlled environment. A typical laboratory testing program usually includes index and performance tests. Read the entire page →
From page 131... ... 131 8.2.1 Sample Tracking During a geotechnical site investigation, it is imperative to properly track samples from the field to the laboratory. Field personnel who collect the soil and rock samples must label each of the samples with a unique identification number. Read the entire page →
From page 132... ... 132 time of drilling to the time just prior to testing. This reduction in effective stress may reduce the measured shear strength and increase the measured compressibility of the laboratory sample compared to the in situ condition. Read the entire page →
From page 133... ... 133 Storing samples in untreated steel containers for long periods of time can increase the occurrence of chemical changes. Sample containers should be coated with lacquer, and sealing caps should be made of inert material or the same material as the container. Read the entire page →
From page 134... ... 134 ' Source: Geosyntec Consultants, Inc. Figure 8-2. Read the entire page →
From page 135... ... 135 Table 8-2 Specimen quality rating system based on change in void ratio Overconsolidation Ratio Δe/e0 @ σʹv0 1–2 <0.04 0.04–0.07 0.07–0.14 >0.14 2–4 <0.03 0.03–0.05 0.05–0.10 >0.10 Rating 1 2 3 4 Description Very good to excellent Good to fair Poor Very poor Source: Lunne et al. Read the entire page →
From page 136... ... 136 Source: Geosyntec Consultants, Inc. Figure 8-3. Read the entire page →
From page 137... ... 137 Source: after Holtz et al. Read the entire page →
From page 138... ... 138 = the total volume of the specimen The saturated unit weight ( ) is defined as the total unit weight under the condition of full saturation (i.e., S = 100%) Read the entire page →
From page 139... ... 139 Table 8-3 Relationship between electric resistivity and corrosion potential Soil Resistivity (ohm-meters) Corrosivity Rating >200 Essentially noncorrosive 100–200 Mildly corrosive 50–100 Moderately corrosive 30–50 Corrosive 10–30 Highly corrosive <10 Extremely corrosive Source: Roberge (2000) Read the entire page →
From page 140... ... 140 Table 8-4. AASHTO soil classification system General Classification Granular Materials (35% or less passing 0.075 mm) Read the entire page →
From page 141... ... 141 Source: AASHTO T 145 Figure 8-5. AASHTO plasticity chart 8.4.2 Unified Soil Classification System Like the AASHTO classification system, the USCS is based on particle-size distribution and the Atterberg limits of the fine-grained portion of the soil. Read the entire page →
From page 142... ... 142 Table 8-5. Unified soil classification system a. Read the entire page →
From page 143... ... 143 Source: ASTM D2487 Figure 8-6. Plasticity chart 8.4.3 Visual-Manual Procedure The visual-manual procedure (ASTM D2488) Read the entire page →
From page 144... ... 144 Soil Type Description Clay Soil that will pass a No. Read the entire page →
From page 145... ... 145 available, including electrical sensing, laser diffraction, particle optical sizing, electron microscopy, and xray diffraction (Abbireddy and Clayton 2009) Read the entire page →
From page 146... ... 146 Source: Geosyntec Consultants, Inc. Figure 8-7. Read the entire page →
From page 147... ... 147 Detailed instructions for conducting and interpreting each type of test are provided in ASTM D5084. Permeation of the specimen should continue until at least four measurements of K have been made for which (i) Read the entire page →
From page 148... ... 148 the ratio of excess pore pressure to vertical effective stress between approximately 3 and 15 percent. The CRS test has several advantages compared to the incremental load test, including better definition of the preconsolidation stress because vertical stress vs. Read the entire page →
From page 149... ... 149 Numerous graphical methods are available to define the preconsolidation stress ( ) from consolidation tests (Ku and Mayne 2013) Read the entire page →
From page 150... ... 150 8.8.1 Miniature Vane Test The miniature vane test is well suited for measuring the undrained shear strength of very soft to soft samples of clay with undrained shear strengths less than approximately 500 psf (23.9 kPa) Read the entire page →
From page 151... ... 151 in Figure 8-11. The confining pressure is used to simulate the in situ stress conditions for the specimen. Read the entire page →
From page 152... ... 152 These errors often lead to significant variability in test results. Ladd and DeGroot (2004) Read the entire page →
From page 153... ... 153 Finally, it is important to recognize that the measured undrained strength will differ for CIU and CK0U tests because of strength anisotropy. Interested readers should see Kulhawy and Mayne (1990) Read the entire page →
From page 154... ... 154 8.8.4 Direct Simple Shear Test The DSS test (ASTM D6528) is used to measure the undrained shear strength of fine-grained soils. Read the entire page →
From page 155... ... 155 Dynamic Properties For transportation facilities subjected to seismic loads, laboratory tests may be used to measure the dynamic properties of soils for use in analysis and design. For analyses to evaluate the potential for ground motion amplification through near-surface materials, the resonant column test may be used to measure the (i) Read the entire page →
From page 156... ... 156 Source: Geosyntec Consultants, Inc. Figure 8-15. Read the entire page →
From page 157... ... 157 major principal stress instantaneously rotates 90°, from vertical to horizontal and then back, whereas in the field, the major principal stress will rotate smoothly and remain nearly vertical. Care should be taken when high cyclic stress ratios are tested. Read the entire page →
From page 158... ... 158 Laboratory Test Methods for Characterizing Subgrade Soils and Unbound Bases for Pavement Design There are three laboratory test methods commonly used to determine the design parameters for pavement subgrade soils and unbound bases: (i) resilient modulus test, (ii) Read the entire page →
From page 159... ... 159 minute and measuring the load required to cause a penetration of 0.1 or 0.2 in. Read the entire page →
From page 160... ... 160 8.11.2 Unit Weight The total and dry unit weights of rock specimens are measured using the same test procedures for soil specimens described in Section 8.3.4. The standardized test procedure is ASTM D7263. Read the entire page →
From page 161... ... 161 8.11.5 Direct Shear Test DS tests (ASTM D5607) determine the shear strength (friction angle and cohesion) Read the entire page →
From page 162... ... 162 Similar to soil, the strength and deformation properties of rock are stress dependent. Methods A and B are used to simulate the in situ stress state of rock. Read the entire page →
From page 163... ... 163 Chapter 8 References AASHTO. Read the entire page →

From page 130...

... 130 C H A P T E R 8 Laboratory Testing of Soil and Rock Introduction Laboratory tests on soil and rock can be used to model existing in situ conditions as well as conditions that will exist at different stages of project development because the tests can systematically characterize the behavior of soil and rock in a controlled environment. A typical laboratory testing program usually includes index and performance tests.