![]() ![]() (ii) Granular cohesionless soils including: angular gravel (similar to crushed rock), silt, silt loam, sandy loam and, in some cases, silty clay loam and sandy clay loam. ![]() (i) Cohesive soil with an unconfined compressive strength greater than 0.5 tsf (48 kPa) but less than 1.5 tsf (144 kPa) or (v) The material is subject to other factors that would require it to be classified as a less stable material. (iv) The soil is part of a sloped, layered system where the layers dip into the excavation on a slope of four horizontal to one vertical (4H:1V) or greater or (iii) The soil has been previously disturbed or (ii) The soil is subject to vibration from heavy traffic, pile driving, or similar effects or Cemented soils such as caliche and hardpan are also considered Type A. Examples of cohesive soils are: clay, silty clay, sandy clay, clay loam and, in some cases, silty clay loam and sandy clay loam. Type A means cohesive soils with an unconfined compressive strength of 1.5 ton per square foot (tsf) (144 kPa) or greater. Submerged soil means soil which is underwater or is free seeping. Stable rock means natural solid mineral matter that can be excavated with vertical sides and remain intact while exposed. The categories are determined based on an analysis of the properties and performance characteristics of the deposits and the environmental conditions of exposure. Soil classification system means, for the purpose of this subpart, a method of categorizing soil and rock deposits in a hierarchy of Stable Rock, Type A, Type B, and Type C, in decreasing order of stability. ![]() Saturation, or near saturation, is necessary for the proper use of instruments such as a pocket penetrometer or sheer vane. Saturated soil means a soil in which the voids are filled with water. Plastic means a property of a soil which allows the soil to be deformed or molded without cracking, or appreciable volume change. Moist granular soil that contains some cohesive material will exhibit signs of cohesion between particles. Moist cohesive soil can easily be shaped into a ball and rolled into small diameter threads before crumbling. Moist soil means a condition in which a soil looks and feels damp. Micaceous seams or weakened planes in rock or shale are considered layered. Layered system means two or more distinctly different soil or rock types arranged in layers. Granular soil cannot be molded when moist and crumbles easily when dry. Some moist granular soils exhibit apparent cohesion. Granular soil means gravel, sand, or silt, (coarse grained soil) with little or no clay content. Cohesive soils include clayey silt, sandy clay, silty clay, clay and organic clay.ĭry soil means soil that does not exhibit visible signs of moisture content.įissured means a soil material that has a tendency to break along definite planes of fracture with little resistance, or a material that exhibits open cracks, such as tension cracks, in an exposed surface. Cohesive soil is hard to break up when dry, and exhibits significant cohesion when submerged. Cohesive soil does not crumble, can be excavated with vertical sideslopes, and is plastic when moist. Department of Agriculture (USDA) Textural Classification Scheme and The National Bureau of Standards Report BSS–121.Ĭemented soil means a soil in which the particles are held together by a chemical agent, such as calcium carbonate, such that a hand-size sample cannot be crushed into powder or individual soil particles by finger pressure.Ĭohesive soil means clay (fine grained soil), or soil with a high clay content, which has cohesive strength. The definitions and examples given below are based on, in whole or in part, the following: American Society for Testing Materials (ASTM) Standards D653–85 and D2488 The Unified Soils Classification System, the U.S. This appendix also applies if other protective systems are designed and selected for use from data prepared in accordance with the requirements set forth in § 1926.652(c), and the use of the data is predicated on the use of the soil classification system set forth in this appendix. This appendix also applies when timber shoring for excavations is designed as a method of protection from cave-ins in accordance with appendix C to subpart P of part 1926, and when aluminum hydraulic shoring is designed in accordance with appendix D. This appendix applies when a sloping or benching system is designed in accordance with the requirements set forth in § 1926.652(b)(2) as a method of protection for employees from cave-ins. The appendix contains definitions, sets forth requirements, and describes acceptable visual and manual tests for use in classifying soils. This appendix describes a method of classifying soil and rock deposits based on site and environmental conditions, and on the structure and composition of the earth deposits.
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