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<br />. <br /> <br />. <br /> <br />;; <br /> <br />. <br /> <br />. <br /> <br />. <br /> <br />e <br /> <br />EM lllO-2-l9l3 <br />31 Mar 78 <br /> <br />CHAPTER 3 <br /> <br />LABORATORY TESTING <br /> <br />3-l. General. <br /> <br />a. Reference should be made to EM lllO-2-l906 (ref. A-3a(7)) for <br />current soil testing procedures, and to EM lllO-2-l902 (ref. A-3a(4)) <br />for applicability of the various shear strength tests in stability <br />analyses. <br /> <br />b. Laboratory testing programs for levees will vary from minimal <br />to extensive, depending on the nature and importance of the project and <br />on the foundation conditions, how well they are known, and whe~her <br />existing experience and correlations are applicable. Since shear and <br />other tests to determine the engineering properties of soils are ex- <br />pensive and time-consuming, testing programs generally consist of water <br />content and identification tests on most samples and shear, consolida- <br />tion, and compaction tests only on representative samples of foundation <br />and borrow materials. It is imperative to use all available data such <br />as geological and geophysical studies, when selecting representative <br />samples for testing. Soil tests that may be included in laboratory <br />testing programs are listed in table 3-l for fine-grained cohesive soils <br />and in table 3-2 for pervious soils, together with pertinent_r~k~ on <br />purposes and scope of testing. <br /> <br />3-2. Classification and Water Content Determinations. After soil <br />samples have been obtained in subsurface exploration of levee founda- <br />tions and borrow areas, the first and essential step is to make visual <br />~lassifications and water content determinations on all samples (except <br />that water content determinations should not be made on clean sands and <br />gravels) . These samples may be jar or bag' samples obtained from test <br />pits, disturbed or undisturbed drive samples, or auger samples. Field <br />descriptions, laboratory classifications, and water content values are <br />used in preparing graphic representations of boring logs. Af'ter examin- <br />ing these data, samples of fine-grained soils are selected for Atterberg <br />limits tests, and samples of coarse-grained soils for gradation tests. <br /> <br />Section I. Fine-Grained Soils <br /> <br />3-3. Use of Correlations. Comparisons of Atterberg limits values with <br />natural water contents of foundation soils and use of the plasticity <br />chart itself (fig. 3-l), together with split-spoon driving resistance, <br />geological studies, and previous experience often will indicate poten- <br />tially weak and compressible fine-grained foundation strata and thus the <br /> <br />3-l <br />