Calculate bulk density, particle density, and porosity using the following formulas. On oven drying, the density drops to 1.74 gm/cc. This discards small aggregate particles clinging to the retained large particles. Bulk density of a soil refers to the mass of a volume of dry soil. s= Density of Soil Compact the soil by dropping onto a padded surface like a book, notebook, etc. Apple (Paid)https://itunes.apple.com/us/app/nickzom-calculator/id1331162702?mt=8 Android (Free)https://play.google.com/store/apps/details?id=com.nickzom.nickzomcalculator For that reason, this value is assumed to be the particle density of any soil sample, unless otherwise specified. First, find the bulk density of the heavier soil sample. Dry overnight. It is similar in nature to the fine aggregate specific gravity test. However, aggregate and asphalt binder volumes are diffucult to measure directly, therefore a materials weight is typically measured and then converted to a volume based on its specific gravity. w s sws w w s s w s s M M . Relation Between Degree of Saturation, Specific Gravity, Water Content, and Void Ratio The degree of saturation may be defined as the ratio of the volume of water in the soil mass to the volume of voids in the soil mass. NTP - Normal Temperature and Pressure - defined as 20 o C (293.15 K, 68 o F) and 1 atm ( 101.325 kN/m2, 101.325 kPa, 14.7 psia, 0 psig, 30 in Hg, 760 torr); Molecular weights can be used to calculate Specific Gravity if the densities of the gas and the air are evaluated at the same pressure and temperature. Any water that escapes from the sample during weighing is considered part of the saturated specimen. However, measuring the volume of pores in a soil sample is difficult. e = void ratio Figure 6: CoreLok sample vacuum sealed in a plastic bag. For instance, deleterious particles (Figure 2) are often lighter than aggregate particles and therefore, a large amount of deleterious material in an aggregate sample may result in an abnormally low specific gravity. This implies that; m = Mass of the Soil = 24 V = Volume of the Soil = 6 s b = m / V s b = 24 / 6 s b = 4 Briefly describe the processes of soil structure (aggregate) formation. SSD is defined as the specimen condition when the internal air voids are filled with water and the surface (including air voids connected to the surface) is dry. Liquids and gases are mostly water and air, respectively. "Good engineers don't need to remember every formula; they just need to know where they can find them. The value of specific gravity (soil) varies between 2.65-2.80. The specific gravity of soil can be calculated by using the following formula,G = Mass of soil / Mass of equal volume of water Where, Mass of Soil = Ws Mass of the same volume of water, Ww = (W1 + Ws) W2 Gs (T1 C) = Ws / Ww, Copyright [2019 - 2023] [Civiconcepts.com] | by [Bhushan Mahajan], 3040 House Plans | 1200 sq ft House Plan, Specific Gravity of Soil Test Procedure, Result & Calculation, General Specific Gravity of Soil Range for Various Soils, Determination of Specific Gravity Test of Soil, Calculation Of Specific Gravity Of Soil Sample, Specific Gravity of Soil at Various Temperature, Specific Gravity of Soil Lab Report Discussion, Water Content of Soil Test Procedure, Result & Report, Ultrasonic Pulse Velocity Test on Concrete, Soundness Test of Cement Procedure and Results, Abrasion Test on Aggregate & Its Procedure, Compressive Strength of Concrete Cube Test Result 7, 14, 28 Days, What To Do If Concrete Cube Fails After 28 days, Cement of Fineness: Definition, Importance, and How to Test It, 8 Different Types Of Mop With Pros & Cons, 5 Different Types of Chains In Civil Engineering, What Is Architecture | 8 Types of Architects | Different Types of Architecture | Top Architecture Types With Pictures, 8 Different Types of Air Conditioners With Pros & Cons, 30 Types Of Shed | Different Types Of Shed In Backyard | Types Of Backyard Shed | Best Shed Styles Designs, 12 Different Types of Gardens | Most Popular Types of Gardening | Top Garden Types With Pictures, Defects In Timber | Top Defects Of Timber | 5 Different Types of Defects In Timber | Foxiness In Timber, Different Types of Chimneys For Kitchens [Pros & Cons], 15 Types of Drywall Anchors | Different Types Of Wall Anchors | Dry Wall Anchors Types | Best Types of Wall Anchors For Wall, Types Of Gutters | 22 Different Types of Gutters | Rain Gutter Downspout | Best Types of Rain Gutter For House, Explore the 15 Different Types of Door Locks for Home Security, 8 Different Types of Kitchen Cabinets for Your Dream Kitchen, 12 Types of Rugs | Different Types of Rugs With Pictures | Best Types of Rug For Living Room | Best Rug For Bedroom, Different Types of Roof Overhang and Their Advantages, 15 Different Types of Fans For Home | Ceiling Fan Type, 10 Different Types of Stoves For Your Kitchen, 22 Different Types of Drill Bits and Their Uses [PDF], Thermometer graduated in O.soC division scale. Now, Click onSoil Mechanics and FoundationunderAgricultural, Now, Click on Specific Gravity of Soil Particle underSoil Mechanics and Foundation. Gs =Unit weight (or density) of soil sample only / Unit weight (or density) or water. Table.1: Observations and Calculations for Specific Gravity of Soil Home Science Classical Physics. ( w) The mean density of water (default is 1,000 kg/m 3) This implies that; w = Density of Water = 22 If more than 2 percent water by volume is absorbed by the sample then this method is not appropriate. Your lab instructor will help you as needed. The determination of the specific gravity method is as follows: The measuring flask with 1000ml capacity is weighed for the determination of its empty weight denoted by W 1. Symbols and Notations, m = unit weight, bulk unit weight, moist unit weightd = Dry unit weightsat = Saturated unit weightb, ' = Buoyant unit weight or effective unit weights = Unit weight of solidsw = Unit weight of water (equal to 9810 N/m3) s /? You must have JavaScript enabled to use this form. INSTRUCTIONS: Choose units and enter the following: () The mean density of the object or liquid. These values are then used to calculate bulk specific gravity, bulk SSD specific gravity, apparent specific gravity and absorption. The wet soil in the box weighed 450 g. The dry soil weighed 375 g. Now calculate the bulk density. w = water content or moisture content, Density of water and gravitational constantw = 1000 kg/m3w = 1 g/ccw = 62.4 lb/ft3 Bulk density is a commonly measured soil property by agriculturalists and engineers. Porosity is the ratio of the volume of the pores in a soil sample to the total volume of the sample: [latex]\text{Porosity, }=\frac{\text{volume of pores}}{\text{total soil volume}}[/latex]. Ws = Weight of solid particles The liquid and gas portions are essential for plant growth and are found in the pore spaces among the soil solids. Aggregate absorption can also vary widely depending upon aggregate type. High values can indicate non-durable aggregate. Engineering Civil Engineering A sand sample has a bulk density of 20kN/m and a degree of saturation of 70%. Low bulk density soils are easily compacted and may settle considerably to the detriment of roads, sidewalks, and building foundations. Thus, the bulk mass density of soil formula is p = M / V . Though not critical, it is important that we know it. 1. In this laboratory, additional physical properties will be measured, and their implications for land management will be discussed. Ww = Weight of water Unit weight is the weight of soil per unit volume. Superpave mix design is a volumetric process; key properties are expressed in terms of volume. Ps = Ms/ (500-Vw) Now that you have the density of soil solids, you can calculate the specific gravity of soil solids (SG). Their common symbols are: (Note: Specific gravity of any element is unit less parameter). Typical values for bulk specific gravity range from 2.200 to 2.500 depending upon the bulk specific gravity of the aggregate, the asphalt binder content, and the amount of compaction. 3 days (from sample preparation to final dry weight determination). Degree of saturation is the ratio of volume of water to the volume of voids. Note that total volume of the soil sample equals the volume of the solids and the volume of the pores. ASTM D 2726: Bulk Specific Gravity and Density of Non-Absorptive Compacted Bituminous Mixtures, AASHTO T 166: Bulk Specific Gravity of Compacted, AASHTO T 275: Bulk Specific Gravity of Compacted Bituminous Mixtures Using Paraffin-Coated Specimens, AASHTO TP 69: Bulk Specific Gravity and Density of Compacted Asphalt Mixtures Using Automatic Vacuum Sealing Method. An introduction to density, specific weight and specific gravity. This method of determining the specific gravity of soil given here is applicable for soils composed of particles smaller than 4.75 mm (No.4 U.S. sieve) in size. Saturated unit weight is the weight of saturated soil per unit volume. So, the bulk density would be 1600 k. Your email address will not be published. 3. = Weight of soil solid in a given soil mass. When the desired depth is reached, the device is removed from the soil, and the removable metal cylinder containing the soil sample is removed. A unit called the slug , equal to 32.17 "mass-pounds" or 14.6 kg, can be used to convert between pounds in the . If particle density remains constant, as bulk density increases porosity decreases. The specimens may have been molded in the laboratory or cut or cored form compacted pavements. Conversely, if the sample is beyond SSD and some of the pore water has evaporated (which is more likely), the mass of the SSD sample will be lower than it ought to be, which will cause a higher calculated bulk specific gravity. The usual standard of comparison for solids and liquids is water at 4 C (39.2 F), which has a density of 1.0 kg per litre (62.4 pounds per cubic foot). A = mass of oven-dry sample in air (g) Accessibility StatementFor more information contact us atinfo@libretexts.orgor check out our status page at https://status.libretexts.org. The equation used to calculate specific gravity is the weight of a dry sample in air divided by the weight of the sample in air minus the weight of the sample in water (i.e., the weight of water displaced by the sample). First of all, we need to kind the density of the object. The complete procedure can be found in: The mass of a coarse aggregate sample is determine in SSD, oven-dry and submerged states. Required fields are marked *. Required fields are marked *. This method calculates specimen volume like the parafilm method but uses a vacuum chamber (Figure 5) to shrink-wrap the specimen in a high-quality plastic bag (Figure 6) rather than cover it in a paraffin film (Video 1). Q & A about Specific Gravity of Soil. Example 4: Determine void ratio, porosity, and degree of saturation based on known volume, weight, and specific gravity (English units) Given: (metric units) Volume of soil mass: 0.0283 m 3. This calculator calculates the bulk specific gravity using weight of dry piece in fluid, density of fluid,. Back in the lab, weigh each canister plus moist soil. The basket should be pre-conditioned to the water bath temperature. Clean and thoroughly dry a 100 mL graduated cylinder. Your email address will not be published. Upon completion of this exercise you should be able to: From Brady and Weil, The Nature and Properties of Soils, 13 th Ed. Bulk density is defined as the mass of the many . Effective Unit Weight, ' The difference between these weights is the weight of absorbed water in the aggregates permeable voids. Thus as soil density increases, soil porosity decreases. W = Total weight of soil The general values for specific gravity for different soils are given in Table -1. Return 50 mL sample in graduated cylinder to 50 mL beaker. Absorption can be used as an indicator of aggregate durability as well as the volume of asphalt binder it is likely to absorb. The complete procedure can be found in: Other standard tests available to determine bulk specific gravity that are not described in this section are: A compacted HMA sample (usually a SGC compacted laboratory sample or a field-obtained HMA core) is weighed dry, saturated surface dry (SSD) and submerged (Figure 1). Take an average of 3 values these values should not vary by more than 2 to 3%. 5.9.15 BULK SPECIFIC GRAVITY AND UNIT WEIGHT OF COMPACTED HOT MIX ASPHALT (HMA) (Kansas Test Method KT-15) 1. The specific gravity of soil may be defined as the ratio of the mass of solids to the mass of an equivalent volume of water at 4C. Mathematically, ASTM D 854 This method is applicable for soils composed of "Particles smaller than 4.75mm in size". Bulk SSD specific gravities can be on the order of 0.050 to 0.100 higher than bulk oven dry specific gravities, while apparent specific gravities can be 0.050 to 0.100 higher still. V = volume of soil Rolling up the aggregate into the towel and then shaking and rolling the aggregate from side to side is usually effective in reducing the sample to a SSD condition (Video 1). Paper towels may absorb water in the aggregate pores. It is an important parameter in soil mechanics for the calculation of the weight-volume relationship. Calculating the Mass of the Soil when the Bulk Density and the Volume of the Soil is Given. Particle density is a measure of the mass of soil solids per given volume (g/cm3 ); however, pore space is not included as it is with bulk density. specific gravity, also called relative density, ratio of the density of a substance to that of a standard substance. s = Density of Soil = 156. Each one uses a slightly different way to determine specimen volume and may result in different bulk specific gravity values. Laboratory samples are typically dry at the beginning of the test; however, field samples will typically be damp. Therefore, by definition, water at a temperature of 73.4F (23C) has a specific gravity of 1. These two (water and air) are called voids which occupy between soil particles. Key Features: Most aggregates have a relative density between 2.4-2.9 with a corresponding particle (mass) density of 2400-2900 kg/m 3 (150-181 lb/ft 3). Remove the aggregate from the water and dry it until it maintains a constant mass. The bulk specific gravity test measures a HMA sample's weight under three different conditions (Figure 1): Dry (no water in sample). Lets solve an example; Absorption, which is also determined by the same test procedure, is a measure of the amount of water that an aggregate can absorb into its pore structure. Grain size analysis is a typical laboratory test conducted in the soil mechanics field. The bulk specific gravity test measures a HMA samples weight under three different conditions (Figure 1): Using these three weights and their relationships, a samples apparent specific gravity, bulk specific gravity and bulk SSD specific gravity as well as absorption can be calculated. Typically, aggregate used in HMA production will have a bulk specific gravity between about 2.400 and 3.000 with 2.700 being fairly typical of limestone. One critical problem with this method is that if a specimens air voids are high, and thus potentially interconnected (for dense-graded HMA this occurs at about 8 to 10 percent air voids), water quickly drains out of them as the specimen is removed from its water bath, which results in an erroneously low HMA sample volume measurement and thus an erroneously high bulk specific gravity. But instead of having g in the formula, use the density of water replacing the unit weight of water. Determine the weight of dry soil in the sample. 1993 AASHTO Flexible Pavement Structural Design, 1993 AASHTO Rigid Pavement Structural Design, Climate Change Impacts on Pavements and Resilience, E-Construction in Practice: A Peer Exchange with WSDOT and TxDOT. Write a mathematical expression for these relationships. Record the final weight of each canister (including the lid) plus oven-dry soil. Weigh and record weight (A). The driving weight is raised and dropped repeatedly to drive the sampler into the soil. If the aggregate is not oven-dried before soaking, specific gravity values may be significantly higher. Dry the material until it maintains a constant mass. D = Density of Fluid. Standard Reference: ASTM D 854-00 - Standard Test for Specific Gravity of Soil Solids Soil porosity is also dependent on, and inversely related to, soil density. Make sure to use cloth and not paper towels. In materials science, bulk density, also called apparent density or volumetric density, is a property of powders, granules, and other "divided" solids, especially used in reference to mineral components (soil, gravel), chemical substances, (pharmaceutical) ingredients, foodstuff, or any other masses of corpuscular or particulate matter ().. W = weight of soil = density of soild = dry density of soilsat = saturated density of soil' = buoyant density of soilw = density of water The total pore space consists of the voids between sand, silt, and clay particles and voids between soil aggregates. m = Mass of the Soil = 45. In this method the specimen is wrapped in a thin paraffin film (Figure 4) and then weighed in and out of water. These weights are used to calculate specific gravity and the percentage of water absorbed by the sample. Ans: Because at 4C the unit weight of water is 1. Certainly, the accuracy of all measurements is important. Using the recommended reading and viewing resources and the introduction to this lab, answer the questions listed below. Their common symbols are: Pavement Interactive was developed by thePavement Tools Consortium, a partnership between several state DOTs, the FHWA, and the University of Washington, as part of their effort tofurther develop and use computer-based pavement tools. Take an average of 3 values these values should not vary by more than 2 to 3%. For example, if spherical (r = radius and = density) . Now, enter the values appropriately and accordingly for the parameters as required by the Mass of the soil (m)is 24 andVolume of the soil (V) is 6. Figure 8: The basket used for underwater weighing. A (relatively) undisturbed, cylindrical soil core is collected using a device like the one shown in Figure 8.1. You can also try thedemoversion viahttps://www.nickzom.org/calculator. w= Density of Water The specific gravity of solid particles is defined as the ratio of the mass of a given volume of solids to the mass of an equal volume of water at 4 C. Saturated Unit Weight, sat h=depth of heave soil prism/unit length pile. Calculation Examples. The formulas for calculating bulk density and particle density follow: Bulk density, b = mass of oven dry soil total soil volume Bulk density, b = mass of oven dry soil total soil volume Particle density, p = mass of oven dry soil volume of soil solids Particle density, p = mass of oven dry soil volume of soil solids Figure 8.1. Theoretical models to predict the capacity of helical piles are based on Soil Mechanics and an appr Seequent, The Bentley Subsurface Company's, Create a free account and view content that fits your specific interests in geotechnical engineering. g = 32.2 ft/sec2. Drying should occur in an oven regulated at 230F (110C). Insert a 1.5 cm metal ring, a 6 cm metal core, and then a second 1.5 cm metal ring into the barrel of the core sampler, then reattach the barrel to the handle. Mass of Soil = Ws Mass of the same volume of water, Ww = (W1 + Ws) - W2 Gs (T1 C) = Ws / Ww Specific Gravity of Soil at Various Temperature For more accurate results it is recommended to conduct tests 3 times on the same soil sample. Soils are composed of a combination of solids (soil particles), liquids (soil water), and gases (soil atmosphere). These definitions/questions will provide a concise summary of the major concepts addressed in the lab. Lets solve an example; Some state agencies specify minimum aggregate specific gravities or maximum percent water absorption to help control aggregate quality. The specific gravity (G S) of a soil refers to the ratio of the solid particles' unit weight to the unit weight of water. Lets solve an example; From $\gamma = \dfrac{(G + Se)\gamma_w}{1 + e}$ and $\gamma = \dfrac{(G + Gw)\gamma_w}{1 + e}$, S = 0 and w = 0, Saturated Unit Weight (S = 1) A sand sample weighing approximately 150 ml is added in the flask and its mass is determined now W 2. To compute for bulk density, two essential parameters are needed and these parameters areMass of the soil (m)andVolume of the soil (V). 6. Submerge sample in 77F (25C) water for 4 minutes and record the submerged mass . It may be necessary to wipe the larger particles separately. The bulk specific gravity test is used to determine the specific gravity of a compacted HMA sample by determining the ratio of its weight to the weight of an equal volume of water. Home Science Classical Physics. The formulas for calculating bulk density and particle density follow: [latex]\text{Bulk density, }_\text{b}=\frac{\text{mass of oven dry soil}}{\text{total soil volume}}[/latex], [latex]\text{Particle density, }_\text{p}=\frac{\text{mass of oven dry soil}}{\text{volume of soil solids}}[/latex]. Bulk specific gravity (Gmb) and the percentage of water absorbed by volume. Now add exactly 50 mL of water to the graduated cylinder, record volume (E). Figure 5 shows major coarse aggregate specific gravity equipment. Data Analysis. Volume of voids, $V_v = \dfrac{eV}{1 + e}$, Volume of solids, $V_s = \dfrac{V}{1 + e}$, Volume of water, $V_w = \dfrac{SeV}{1 + e}$, Weight of water, $W_w = \dfrac{SeV \gamma_w}{1 + e}$, Weight of soil, $W = \dfrac{V(G + Se)\gamma_w}{1 + e}$, Dry unit weight, $\gamma_d = \dfrac{\gamma_m}{1 + w}$. Find the density of water? Organic matter and porous particles may havespecific gravityvalues below 2.0 and Soil which has heavy substances or particles may have values above 3.0. It is denoted by G. Selected Topics. The formula for calculating specific gravity of soil particle: G s = s / w Where: G s = Specific Gravity of Soil Particle w = Density of Water s = Density of Soil Let's solve an example; Find the specific gravity of soil particle when the density of water is 22 and the the density of soil is 11. Examples of suitable units have been shown below. To get the answer and workings of the bulk density using the Nickzom Calculator The Calculator Encyclopedia. W b = Weight of Pycnometer filled with water and soil. Several important physical properties have been discussed in other labs: texture, structure, color, and consistency. Use a soil spatula to level the top of the sample in the graduated cylinder and add soil with the spatula until the top of the soil sample is exactly even with the 50 mL line this is the bulk volume of compacted soil (B) (1 mL = 1 cm3 ). Weight of soil mass at moist condition: 56.6 kg. The LibreTexts libraries arePowered by NICE CXone Expertand are supported by the Department of Education Open Textbook Pilot Project, the UC Davis Office of the Provost, the UC Davis Library, the California State University Affordable Learning Solutions Program, and Merlot. The final specific gravity is calculated following the specific gravity of soil formulas in the test method, along with the density of water and temperature coefficient tables. Accessed 1 July 2002. The specific weight, , of a material is defined as the product of its density, , and the standard gravity, g: =g{\displaystyle \gamma =\rho \,g} The densityof the material is defined as massper unit volume, typically measured in kg/m3. Specific gravity of solid = 2.65. You can also try thedemoversion viahttps://www.nickzom.org/calculator. V = Volume of the Soil = 6. Define and explain the differences among particle density, bulk density, and specific gravity. Although it avoids problems associated with the SSD condition, it is often inaccurate because it assumes a perfectly smooth surface, thereby ignoring surface irregularities (i.e., the rough surface texture of a typical specimen). The above values have been provided with both imperial and metric units. w. The mass density of water ? To find it, divide the density of soil solids by the density of water (Pw), which is 1,000 kg/m3. Troxler Electronic Laboratories, Inc. Research Triangle Park, NC. Organic matter affects the solids portion of the soil but also influences porosity indirectly through its effect on structure. 5. sb= Bulk Density The density of a fully saturated specimen of clay having a water content of 40% is 1.88 gm/cc. Void Ratio, e g/cm3 ), including solids and pore spaces. Therefore, after the wax sets there is no possibility of it draining out and, theoretically, a more accurate volume can be calculated. The jar is now included with 100ml of mineral water. Porosity is the ratio of volume of voids to the total volume of soil. S = degree of saturation of the soil Some lightweight shales (not used in HMA production) can have specific gravities near 1.050, while other aggregate can have specific gravities above 3.000. In this video we discuss in detail about the difference among apparent , bulk & effective specific gravity of aggregate. Find the specific gravity of soil particle when the density of water is 22 and the the density of soil is 11. w = Density of Water = 22 Void ratio is the ratio of volume of voids to the volume of solids. You will be working with your classmates to complete it during lab. Recall that Specific Gravity is the ratio of the density of a substance to the density of water. The following formulas are taken from unit weights of soil: = ( G + S e) w 1 + e = ( G + G w) w 1 + e d = G w 1 + e s a t = ( G + e) w 1 + e = ( G 1) w 1 + e Where m = mass of soil V = volume of soil W = weight of soil = density of soil d = dry density of soil sat = saturated density of soil ' = buoyant density of soil It is often found that the specific gravity of the materials making up the soil particles are close to the value for quartz, that is Gs 2.65 For all the common soil forming minerals 2.5 < Gs < 2.8 We can use Gs to calculate the density or unit weight of the solid particles s = Gs w s = Gs w Slowly add Soil Sample #1 to pre-weighed graduated cylinder to the 10 mL line. emin = void ratio of the soil at its densest conditiond = current dry unit weight of soil in-situ From $\gamma = \dfrac{(G + Se)\gamma_w}{1 + e}$, S = 100%, Buoyant Unit Weight or Effective Unit Weight (2000c). The results are as follows: Aggregate A: Bulk specific gravity=2.814; absorption=0.4% Aggregate B: Bulk specific gravity=2.441; absorption=3.0% What is the specific gravity of a mixture of 35% aggregate A and 65% aggregate B by weight? Although the Test Description section describes the standard AASHTO T 166 saturated surface dry (SSD) water displacement method, there are a number of other methods available. m = Mass of the Soil. Both use the same aggregate volume. Ans: The unit weight of any material divided by the unit weight of distilled water. 4 (4.75 mm) sieve. Between 20o C and 25o C the density of water is essentially 1 g/cm3. $\gamma_{sat} = \dfrac{W_{sat}}{V_{sat}}$, $e = \dfrac{n}{1 - n}$ and $n = \dfrac{e}{1 + e}$, MATHalino - Engineering Mathematics Copyright 2023. What are the sizes of macropores and micropores? The flow of liquids and through soil is essential for the existence of plants and other soil organisms. The pu What is Soil Consolidation? Bulk density is the density of a "bulk" of a substance, typically expressed in kg/m3 or similar. This method, the simplest, calculates the volume based on height and diameter/width measurements. If absorption is incorrectly accounted for, the resulting HMA could be overly dry and have low durability (absorption calculated lower than it actually is) or over-asphalted and susceptible to distortion and rutting (absorption calculated higher than it actually is). W'= Submerged weight of soil in the heave zone per unit width of sheet pile U= Uplift force due to seepage on the same volume of soil 2 W'= D ( sat - w )/2= D 2 '/2, Where, D= is the depth of embedment into Permeable soil U= D2 .