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Cracks are also very influential in gas exchange, influencing respiration within soils. Modeling cracks therefore helps understand how these processes work and what the effects of changes in soil cracking such as compaction, can have on these processes. The pore space of soil may contain the habitat of plants (rhizosphere) and microorganisms.
The R-Value test [1] measures the response of a compacted sample of soil or aggregate to a vertically applied pressure under specific conditions. This test is used by Caltrans for pavement design, replacing the California bearing ratio test.
The ability of the first fill layers to be properly compacted will depend on the condition of the natural material being covered. If unsuitable material is left in place and backfilled, it may compress over a long period under the weight of the earth fill, causing settlement cracks in the fill or in any structure supported by the fill. [4]
When a fill material is being selected for a project such as a highway embankment or earthen dam, the soil gradation is considered. A well graded soil is able to be compacted more than a poorly graded soil. These types of projects may also have gradation requirements that must be met before the soil to be used is accepted.
Fill dirt is taken from a location where soil is being removed as a part of leveling an area for construction; it may also contain sand, rocks, and stones, as well as earth. Fill dirt should be as free of organic matter as possible since organic matter will decompose creating pockets of empty space within the fill which could result in settling ...
Meyerhof (1951, 1963) proposed a bearing-capacity equation similar to that of Terzaghi's but included a shape factor s-q with the depth term Nq. He also included depth factors and inclination factors. [Note: Meyerhof re-evaluated N_q based on a different assumption from Terzaghi and found N_q = ( 1 + sin phi) exp (pi tan phi ) / (1 - sin phi).
There are various factors that affect soil temperature, such as water content, [84] soil color, [85] and relief (slope, orientation, and elevation), [86] and soil cover (shading and insulation), in addition to air temperature. [87] The color of the ground cover and its insulating properties have a strong influence on soil temperature. [88]
Newmark's Influence Chart is an illustration used to determine the vertical pressure at any point below a uniformly loaded flexible area of soil of any shape. This method, like others, was derived by integration of Boussinesq's equation for a point load.