Explain the effect of water table on bearing capacity of soil.

Explain the effect of water table on bearing capacity of soil.
by

2 Answers

Answer :

Effect of water table on bearing of capacity of soil:

1. When the water table reaches the ground where the depth is greater footing the bearing capacity is reduced by 50% or more.

2. The bearing capacity is not affected for purely cohesive soil.

3. The bearing capacity for non-granular soil decreases with presence of water table.

4. Presence of water table for shallow depth give poor bearing capacity as compared for larger depth foundation.

5. When water table is above base of footing-submerged weight of soil should be considered for bearing capacity.

6. When water table is somewhat below the base of footing-elastic wedge is partially saturated soil should be considered.

7. When water table is at a depth D equal to width of footing below the base of footing-a linear interpolation in reduction factor should be made for bearing capacity calculations.

8. As ground water table rises accordingly bearing capacity of soil decreases.


by

Answer :

Effect of water table on bearing capacity of soil:

i. The rise in water table from below the foundation results in decrease in granular soil.

ii. When the water table reaches the ground where the depth is greater footing the bearing capacity is reduced by 50% or more.

iii. The bearing capacity is not affected for purely cohesive soil.

iv. The bearing capacity for non-granular soil decreases with presence of water table.

v. Presence of water table for shallow depth give poor bearing capacity as compared for larger depth foundation.

vi. When water table is above base of footing-submerged weight of soil should be considered for bearing capacity.

vii. When water table is somewhat below the base of footing-elastic wedge is partially saturated soil should be considered.

viii. When water table is at a depth D equal to width of footing below the base of footing-a linear interpolation in reduction factor should be made for bearing capacity calculations.

ix. As ground water table rises accordingly bearing capacity of soil decreases.
by

Related questions

Explain plate load test with neat sketch to determine bearing capacity of soil.

Description : Explain plate load test with neat sketch to determine bearing capacity of soil.

Last Answer : Procedure of plate load test: 1. Excavate a pit of depth equal to 5 times to that of breath of proposed footing. 2. Keep the suitable bearing plate of specified size (30, 45, 60, 75cm square in plan) ... as shown in figure below to find out load before failure as bearing capacity of soil.

Define ultimate bearing capacity and safe bearing capacity.

Description : Define ultimate bearing capacity and safe bearing capacity.

Last Answer : Ultimate bearing capacity (qu): It is the gross pressure at the base of the foundation at which the soil fails in shear is called as ultimate bearing capacity. Safe bearing capacity (qs) : It ... capacity is also referred to as the ultimate bearing capacity qu divided by factor of safety F.

Define safe bearing capacity and allowable bearing pressure.

Description : Define safe bearing capacity and allowable bearing pressure. 

Last Answer : Safe bearing capacity (qs): It is the maximum pressure which the soil can carry without risk of shear failure is called as safe bearing capacity.  OR Sometimes the safe bearing capacity is ... in shear nor there is excessive settlement of structure, is called as Allowable bearing pressure.

Write any four methods of improving bearing capacity.

Description : Write any four methods of improving bearing capacity.

Last Answer : Methods of improving bearing capacity of soil. i. By increasing depth of foundation: At deeper depths the over burden pressure on soil is higher hence soil is more compacted at deeper depth. As ... In this method poor soil bearing strata is hardened by injecting the cement grout under pressure. 

Explain California bearing Ratio Test with neat sketch to determine % CBR of given soil sample.

Description : Explain California bearing Ratio Test with neat sketch to determine % CBR of given soil sample.

Last Answer : Procedure of California Bearing Ratio Test: 1. Take a given soil; sample and add water equal to OMC of soil to prepare wet mix soil. 2. Take the CBR mould of 150 mm diameter and 175 mm height. Keep it ... Bearing Ratio of given soil as  % CBR = (Test load / Standard load ) X 100.

Explain dry strength and Dilatancy test on soil.

Description : Explain dry strength and Dilatancy test on soil. 

Last Answer : This is simple test which is used in the field for rough classification of soil. i) The prepared soil sample is completely dried in the sun or by air drying. Its strength is ... reaction is observed and recorded; inorganic soils exhibit a quick reaction whereas clays exhibit known to slow.

Explain laboratory procedure for mechanical sieve analysis of soil.

Description : Explain laboratory procedure for mechanical sieve analysis of soil.

Last Answer : Laboratory Procedure for mechanical sieve Analysis Mechanical in laboratory 1) Dry sieve Analysis 2) Wet sieve analysis Apparatus required for test - i) Weighing balance accurate to 1g and 0.1g ... through the set of sieves. The material retained on each sieve is weighed and analysed

State different methods of soil stabilization and explain any one

Description : State different methods of soil stabilization and explain any one

Last Answer : i) Mechanical stabilization - It is the process of improving properties of soil by changing its gradation. It depends on mechanical strength of aggregate, mineral composition etc Eg - Compaction at near ... help to drain water, increase strength, decrease mixing of soil, filters the water etc. 

Explain different methods of field compaction of soil.

Description : Explain different methods of field compaction of soil.

Last Answer : Methods of field compaction of soil i) Rolling- In this method, soil is compacted by using 6-8 tonne heavy rollers. The rollers are selected as per type of soil. Due to ... compactors. Vibrations of large amplitude, rearrange the soil particles together and hence overall compaction takes place.

Draw particle size distribution curve. Explain mechanical sieve analysis for grading of soil with a sketch.

Description : Draw particle size distribution curve. Explain mechanical sieve analysis for grading of soil with a sketch.

Last Answer : Mechanical sieve analysis -The process of analyzing the particle size present in soil by using mechanical means, is known as mechanical sieve Analysis. By performing mechanical sieve analysis, a particle size ... c) Fine grained soil d) Coarse grained soil e) Uniformly graded soil

Explain the use of soil as a foundation material.

Description : Explain the use of soil as a foundation material.

Last Answer : i) The foundation is rest on the soil ii) Soil-cement mixture used as sub grade. iii) Pervious and impervious soil is used in earthen dams iv) Soil used as bed of foundation

Explain I.S. classification of soil

Description : Explain I.S. classification of soil

Last Answer : I.S. classification of soil: The soils are classified by Indian standard code i.e. IS 1498:1970 into three categories. 1.Coarse grained soil: In these soils, more than half ... , concretions, cinders and other non-soil materials in sufficient quantities are grouped under this category.

Define specific gravity of soil. Explain the stepwise procedure of determination of specific gravity of soil by pycnometer.

Description : Define specific gravity of soil. Explain the stepwise procedure of determination of specific gravity of soil by pycnometer. 

Last Answer : Specific Gravity: It is ratio of unit weight in air of a given volume of soil solids at a specific temperature to unit weight in air of an equal volume of distilled water at same temperature. ... Repeat all above steps two more times to calculate average specific gravity of given soil sample.

Explain three phase system of soil.

Description : Explain three phase system of soil.

Last Answer : As natural soil contains solid soil particles and water and air present in its voids such complex nature of soil sample is difficult to analyze its physical properties hence it is simplify and ... water. In case of partially saturated soil, both air and water are present in the voids.

Classify the soil according to IS Classification and explain the meaning of following terms i) GW ii) SP iii) ML iv) SM-ML

Description : Classify the soil according to IS Classification and explain the meaning of following terms i) GW ii) SP iii) ML iv) SM-ML

Last Answer : As per IS classification soil is broadly divided into three divisions: 1. Coarse grained soil: In these soils, more than half the total material by mass is larger than 75 micron IS ... medium compressibility. iv) SM-ML - boundary classification between coarse grained and fine grained soils. 

Enlist field identification test on soil and explain dilatency test.

Description : Enlist field identification test on soil and explain dilatency test.

Last Answer : Field Identification test on soil:- 1) Dry Strength Test 2) Dilatency Test 3) Toughness Test 4) Organic content and colour test 5) Visual examination. 6) Other identification test. ... and recorded. Inorganic silts show a quick reaction where as clays shows no reaction or slow reaction.

State and explain the failure of soil on the basis of Terzaghi’s analysis

Description : State and explain the failure of soil on the basis of Terzaghi’s analysis 

Last Answer : On the basis of Terzaghi's analysis the three types of shear failure occurs; i. General shear failure: When footing is rested on dense sand or stiff clay, the settlement increases ... the settlement increases vertical diraction at particular loading is called as Punching shear failure. 

Explain vane shear test carried on given soil sample.

Description : Explain vane shear test carried on given soil sample.

Last Answer : i) The undrained shear strength of soft clays can be determined in a laboratory by a vane shear test ii) Apparatus - A) Consist of a vertical steel rod having four thin stainless steel blades fixed at ... Only bottom end partakes in shearing where τ is in N / mm2 and T is in N - mm

Explain the formation process of soil.

Description : Explain the formation process of soil. 

Last Answer : Formation process of soil: Soil formation mainly takes place due to mechanical disintegration or chemical decomposition of rocks whenever rock get exposed to atmosphere, It is acted by various weathering ... it gets disintegrates or decomposed into small particles & then it is converted into soil. 

Enlist the physical properties of soil and explain any one of them.

Description : Enlist the physical properties of soil and explain any one of them.

Last Answer : Physical properties of soil: 1. Void ratio ( e ) 2. Porosity ( n ) 3. Degree of saturation ( s ) 4. Density index ( ID ) 5. Density ( p ) Void ratio ( e ): The ratio of volume of voids (VV = Va + VW) to the total volume (V) of solids is called as void ratio. 

Explain the determination of liquid limit of soil with neat sketches.

Description : Explain the determination of liquid limit of soil with neat sketches.

Last Answer : Procedure of Liquid Limit Test: 1. Take about 120 gm. of air dried soil sample passing through 425 micron IS sieve in metal tray. Add 20 % distilled water to the soil sample to form uniform soil ... content corresponding to 25 blows from graph as liquid limit (WL) of given soil sample.  

Explain standard proctor test on soil to determine OMC and MDD of soil with sketch.

Description : Explain standard proctor test on soil to determine OMC and MDD of soil with sketch.

Last Answer : Procedure of Standard Proctor Test: 1. Take about 5 Kg. of de-aired soil passing through sieve 20 mm in tray. Add about 4% water (approximately 120 ml) to the soil and mix thoroughly with ... corresponding to the standard proctor compaction by plotting graph water content v/s. dry density.    

Explain the direct shear test to determine shear strength of soil.

Description : Explain the direct shear test to determine shear strength of soil.

Last Answer : Procedure for Direct Shear Test: 1. Take 2.5 Kg air dried soil sample passing through 4.75 mm and retained on 2.36mm IS sieve. 2. Measure the internal dimensions of the shear box. Fix ... value Normal Stress as abscissa and the maximum shearing stress as ordinate to find shear strength of soil.

Explain the mechanical sieve analysis test carried out on soil sample to classify it.

Description : Explain the mechanical sieve analysis test carried out on soil sample to classify it.

Last Answer : Procedure of mechanical sieve analysis test: 1. Initially keep the given soil sample in rapid moisture meter for 2-3 hours to get oven dried soil. Break the visible lumps present in soil using ... . Well graded soil, poorly graded soil, uniformly graded soil, fine grained soil, coarse grained soil.

Explain the determination of plastic limit of soil.

Description : Explain the determination of plastic limit of soil.

Last Answer : Procedure for determination of plastic limit of soil: 1. Take 20-25 gm air dried soil sample passing through 425 micron IS sieve. 2. Add distilled water in soil and mix it thoroughly for 10-15 ... all above steps two more tones to get average water content as plastic limit (WP) given soil sample.

Explain the formation process of soil and state any two types of soil in India.

Description : Explain the formation process of soil and state any two types of soil in India.

Last Answer : Soil formation: Soil formation mainly takes place due to mechanical disintegration or chemical decomposition of rocks whenever rock get exposed to atmosphere, it is acted by various weathering agencies and it gets ... soil ii. Alluvial soil iii. Glacial soil iv. Lacustrine soil v. Eolian soil  

State any four methods to find water content of soil sample.

Description : State any four methods to find water content of soil sample. 

Last Answer : The direct determination of moisture content can be made by a) Oven drying b) Infrared c) Sand bath method. The indirect method are a) Calcium carbide b) Penetration resistance (proctor needle) c) Nuclear d) Pycnometer 

Define water content and voids ratio of soil.

Description : Define water content and voids ratio of soil.

Last Answer : Water content- It is the ratio of weight of water to weight of soil soilds which is measured in percentage called as water content.  Voids ratio – It is the ratio of volume of voids to volume of solids called as voids ratio.

Define Soil Stabilization. State any three points of necessary of soil stabilization.

Description : Define Soil Stabilization. State any three points of necessary of soil stabilization.

Last Answer : Define: - Soil Stabilization is defined as improving the engineering performance of soil by artificial means. Necessity of Soil Stabilization : - 1. To increase the shear strength of soil. 2. To reduce ... of structures. 6. To increase the density of soil. 7. To reduce permeability of soil.

Give the IS Definition of soil.

Description : Give the IS Definition of soil.

Last Answer : As per Indian standards 2809-1972:  Soil is the sediment or other unconsolidated accumulation of solid particles produced by physical and chemical disintegration of rock. 

Define shear strength of soil and state field situations of shear failure.

Description : Define shear strength of soil and state field situations of shear failure. 

Last Answer : Shear Strength of Soil: Shear strength is a term used in soil mechanics to describe the magnitude of the shear stress that a soil can sustain. . Field situations where shear failure occurs 1) ... wall, especially surcharge 3)Under foundation along planes of maximum shear 4) Sub grades of road.

Write step by step procedure to determine coefficient of permeability of fine grained soil by falling head method in laboratory.

Description : Write step by step procedure to determine coefficient of permeability of fine grained soil by falling head method in laboratory.

Last Answer : This method is suitable for fine grained soil as quantity of water collected through soil mass is very less and cannot be measured accurately 2. The falling head test is used for relatively less permeable ... equal to the difference of water level in the stand pipe and the bottom tank. 

What do mean by coarse grain soil and fine grained soil.

Description : What do mean by coarse grain soil and fine grained soil.

Last Answer : Coarse Grain Soil:- 1. If more than 50% of soil is retained on sieve 0.075mm it is called as coarse grain soil. 2. A coarse grain soil is called as gravel if 50% or more of the ... liquid limit is less than 50% or more than 50% respectively. Organic soil are also included in fine grain soil.

Write step by step procedure to determine specific gravity of soil by pycnometer in laboratory.

Description : Write step by step procedure to determine specific gravity of soil by pycnometer in laboratory.

Last Answer : 1. Clean the pycnometer and dry it, find the mass of pycnometer, brass cap and washer accurate to 1g. say M1 2. Put about 200gm to 400gm of wet soil sample in pycnometer and find its mass with its cap ... it top of cap and find its weight say M4. 5. The specific gravity is calculated by 

State formation and classification of soil.

Description : State formation and classification of soil.

Last Answer : Soils are formed by numerous process of weathering both physical and chemical. A boulder pried loose from the side of mountain by rapidly flowing water of river and came along with the water ay has result of ... parent rocks. a) Colluvial soil b) Alluvial soil c) Glacial soil d) Eolian soil

State any four factors which affect shear strength of soil

Description : State any four factors which affect shear strength of soil

Last Answer : Shear strength is affected by i) Soil composition Mineralogy, grain size, shape of soil particles, pore fluid type and content, clay content. ii) Initial State Loose, ... Drainage conditions Undrained, drained vii) Stress conditions deviator stress, confining stress, intermediate stress 

Define plasticity index and classify soil on its basis.

Description : Define plasticity index and classify soil on its basis.

Last Answer : a) Plasticity index (Ip) It is give measure of degree of plasticity of soil. It is difference be liquid limit and plastic limit Ip = WL - Wp Greater plasticity index, the greater is degree of plasticity of the soil. ... based on Ip i) Non plastic soil  If wp = o        Ip = wL ii) Plastic soil

Give necessity of site investigation and sub soil explorations.

Description : Give necessity of site investigation and sub soil explorations.

Last Answer : Necessity of Site investigation - 1. To determine bearing capacity of soil 2. To select suitable construction techniques 3.To select the type and depth of foundation for given structure 4.To ... soil sample and classify soil accordingly 7. To decide suitability of soil for proposed structure. 

State any four importance of soil in civil engineering.

Description : State any four importance of soil in civil engineering. 

Last Answer : 1. Soil is more suitable in embankment fills and retaining pond beds after their construction. 2. Soil is also suitable for foundation but require compactions as without compaction structure may collapse. 3. ... earthen dams. 8. For Water bound macadam roads soil is used as a binder material. 

State any two situations where knowledge of soil mechanics is required.

Description : State any two situations where knowledge of soil mechanics is required.

Last Answer : 1. Design of foundation for various structures. 2. Design of pavement for various roads. 3. Design of earth retaining structures i.e. retaining wall, sheet pile. 4. Design of water retaining ... Design of abutments of bridge. 6. Design of underground structures i.e. pipeline, tunnels etc. 

Write any four uses of Soil Stabilization.

Description : Write any four uses of Soil Stabilization. 

Last Answer : Uses of Soil Stabilization is as follows, 1. To increase the shear strength of soil. 2. To reduce construction cost by use of locally available material. 3. To improve stability of slopes. 4. ... settlement of structures. 6. To increase the density of soil. 7. To reduce permeability of soil. 

Differentiate between Cohsionless soil and purely cohesive soil

Description : Differentiate between Cohsionless soil and purely cohesive soil 

Last Answer : Cohsionless soil  Purely cohesive soil  1) Interaction or bond between soil particles is absent.  1) Interaction or bond between soil particles is perfect.  2) Shearing resistance is only the ... is coarse, gravel, sand, silt etc 5) Type of soil is soft shale, clay etc 

Write any two uses of soil as construction material

Description : Write any two uses of soil as construction material 

Last Answer : Uses of soil as construction material: 1. Clay the most widespread masonry material. 2. Pervious & impervious soil is used in earth dams. 3. Water bound macadam roads or WBM roads. 4. Canals & Embankments. 5. River protection works. 6. Soil cement mixture used as subgrade. 

State the necessity of soil exploration. What is the criterion for deciding the number of test-pits for site investigation?

Description : State the necessity of soil exploration. What is the criterion for deciding the number of test-pits for site investigation?

Last Answer : Necessity of site exploration: 1. To know stratification below ground surface. 2. To determining index properties of soil like bulk density, voids ratio, water content, permeability, bearing capacity, ... should be taken along top line of upstream side across the abutments with 50 m spacing. 

State two uses of soil.

Description : State two uses of soil.

Last Answer : Uses of soil: 1. Soil is used as construction material to manufacturing of clay bricks for masonry. 2. The murum is used for plinth filling in the building construction. 3. Natural ... in the form of supporting soil for various civil engineering structures like building, road, bridge etc.

Draw three phase diagram for partially saturated soil.

Description : Draw three phase diagram for partially saturated soil. 

Last Answer : Figure : Three Phase Diagram for Partially Saturated Soil 

State any four factors affecting compaction with their effect.

Description : State any four factors affecting compaction with their effect.

Last Answer : Following the different factors affecting compaction of soil with their effect: Water content : When water content is less i.e. dry soil , compaction is not better , but when water ... better compaction. Hence lesser thickness of soil layers can be effectively compacted to required density.

Write any two causes and effect of earthquakes.

Description : Write any two causes and effect of earthquakes. 

Last Answer : Causes of earthquake - 1. Volcanic eruption 2. Technical movements 3. Natural disaster like landslide, tsunami 4. Massive civil structures like dams, reservoirs 5. High water flows 6. Manmade ... tidal waves 7. Fire exposure due to short circuiting 8. Loss of human life and property

The rise of water table below the foundation influences the bearing capacity of soil mainly by reducing (A) Cohesion and effective angle of shearing resistance (B) Cohesion and effective unit weight of soil (C) Effective unit weight of soil and effective angle of shearing resistance (D) Effective angle of shearing resistance

Description : The rise of water table below the foundation influences the bearing capacity of soil mainly by reducing (A) Cohesion and effective angle of shearing resistance (B) Cohesion and effective ... weight of soil and effective angle of shearing resistance (D) Effective angle of shearing resistance

Last Answer : Answer: Option B

If water table is encountered in the standard pit while conducting plate load test (a) The load test should be abandoned (b) The pit is considered unsafe (c) Test should be conducted with complete dewatering continuously throughout the test duration (d) The bearing capacity of soil cannot be determined in this condition

Description : If water table is encountered in the standard pit while conducting plate load test (a) The load test should be abandoned (b) The pit is considered unsafe (c) Test should be conducted ... continuously throughout the test duration (d) The bearing capacity of soil cannot be determined in this condition

Last Answer : (c) Test should be conducted with complete dewatering continuously throughout the test duration