Test 25 - Foundation Settlement Analysis

Question 1 ప్రశ్న 1

A foundation on saturated clay undergoes deformation during loading, further settlement while excess pore-water pressure dissipates, and continued slow compression after primary consolidation. Which sequence correctly names the three components?

A Primary consolidation, secondary compression, immediate settlement. B Immediate settlement, primary consolidation settlement, secondary compression settlement. C Secondary compression, immediate settlement, primary consolidation. D Elastic rebound, heave, bearing shear failure.

Question 2 ప్రశ్న 2

A proposed building has one footing on dense free-draining sand and another on thick normally consolidated saturated clay. Which statement best describes their expected settlement behaviour under sustained loading?

A Both soils must experience the same consolidation time because the footing loads are equal. B Sand can undergo only secondary settlement, whereas clay can undergo only immediate settlement. C A substantial portion of sand settlement may develop during loading, whereas the clay can undergo prolonged primary consolidation and possibly secondary compression. D A lower permeability in clay guarantees smaller ultimate settlement than in dense sand.

Question 3 ప్రశ్న 3

For a foundation, the estimated immediate settlement is 18 mm, ultimate primary consolidation settlement is 72 mm, and secondary settlement over the stated design period is 15 mm. Assuming these are distinct additive components, what is the estimated total settlement over that period?

A 105 mm. B 90 mm. C 87 mm. D 72 mm.

Question 4 ప్రశ్న 4

Use the given elastic settlement expression Si = q B (1 - nu^2) I / Es for a uniformly loaded flexible shallow footing. If q = 200 kPa, B = 2 m, nu = 0.30, I = 1.10 and Es = 20000 kPa, what is Si approximately?

A 11.0 mm. B 18.2 mm. C 22.0 mm. D 20.0 mm.

Question 5 ప్రశ్న 5

Immediately after rapid loading of saturated clay, the vertical total-stress increment at a point is 80 kPa and the excess pore-pressure increment is 70 kPa. At long-term drained equilibrium, assume the excess pore pressure has dissipated completely and the total-stress increment remains 80 kPa. Which pair of effective-stress increments is correct?

A 80 kPa immediately and 10 kPa finally. B 70 kPa immediately and 80 kPa finally. C 10 kPa immediately and 80 kPa finally. D 10 kPa immediately and 10 kPa finally.

Question 6 ప్రశ్న 6

A shallow footing bears on heterogeneous cohesionless soil, and the design engineer must estimate settlement without relying on high-quality undisturbed sand samples. Which investigation-based approach is most defensible?

A Use only the soil colour as a direct settlement modulus. B Interpret suitable SPT, CPT or plate-load results using a stated, applicable correlation and check the depth and variability of the stressed zone. C Apply a universal fixed settlement value to all sand deposits regardless of density and footing size. D Use the undrained compression index of a nearby clay without investigating the sand.

Question 7 ప్రశ్న 7

A 4 m thick normally consolidated clay layer has initial void ratio e0 = 0.80 and compression index Cc = 0.24. The representative vertical effective stress increases from 100 kPa to 200 kPa. Using Sc = H Cc/(1 + e0) log10(sigma_f'/sigma_0'), calculate the ultimate primary settlement.

A 80.3 mm. B 120.4 mm. C 240.8 mm. D 160.5 mm.

Question 8 ప్రశ్న 8

Two compressible layers beneath a raft have different coefficients of volume compressibility. Layer 1 has H1 = 2 m, mv1 = 3.0 x 10^-4 kPa^-1 and average effective-stress increase 60 kPa; Layer 2 has H2 = 3 m, mv2 = 6.0 x 10^-4 kPa^-1 and increase 40 kPa. Using S = mv DeltaSigma' H for each layer, what is the combined settlement?

A 108 mm. B 72 mm. C 144 mm. D 36 mm.

Question 9 ప్రశ్న 9

An overconsolidated clay layer is 3 m thick, with e0 = 0.75 and recompression index Cr = 0.05. Its initial effective vertical stress is 100 kPa, preconsolidation pressure is 200 kPa, and the final effective stress is 150 kPa. What primary settlement is predicted using the recompression branch alone?

A 30.2 mm. B 45.3 mm. C 15.1 mm. D 60.4 mm.

Question 10 ప్రశ్న 10

A 4 m thick overconsolidated clay layer has e0 = 1.00, Cr = 0.05 and Cc = 0.25. Initial effective stress is 100 kPa, preconsolidation pressure is 150 kPa, and final effective stress is 300 kPa. Using separate recompression and virgin-compression branches, calculate primary settlement.

A 75.3 mm. B 168.1 mm. C 150.5 mm. D 336.2 mm.

Question 11 ప్రశ్న 11

An embankment over saturated clay is estimated to cause 120 mm of ultimate primary consolidation settlement and 20 mm of immediate settlement. At a particular time the average degree of primary consolidation is U = 65%, and secondary settlement is negligible so far. What total settlement should have occurred by that time?

A 78 mm. B 85 mm. C 140 mm. D 98 mm.

Question 12 ప్రశ్న 12

A saturated clay stratum is 4 m thick with cv = 0.040 m2/day. Use time factor T50 = 0.197 and t50 = T50 Hdr^2/cv. What are the times for 50% average consolidation under single drainage and double drainage, respectively?

A 78.8 days and 19.7 days. B 19.7 days and 78.8 days. C 39.4 days and 19.7 days. D 78.8 days and 39.4 days.

Question 13 ప్రశ్న 13

A 3 m thick clay layer has void ratio e_p = 0.80 at the end of primary consolidation at t1 = 1 year after loading. Its secondary compression index C_alpha = 0.04 is defined as the decrease in void ratio per log10 time cycle. Assuming constant effective stress and C_alpha, what is the secondary settlement from t1 = 1 year to t2 = 10 years? Use Ss = C_alpha H/(1 + e_p) log10(t2/t1).

A 22.2 mm. B 40.0 mm. C 66.7 mm. D 120.0 mm.

Question 14 ప్రశ్న 14

A soft organic deposit continues to compress slowly after the excess pore-water pressure generated by construction has substantially dissipated. Which action best addresses its potential effect on a long-service-life water-treatment structure?

A Assume long-term movements end as soon as primary consolidation is complete. B Use the bearing-capacity factor of safety as a direct substitute for a secondary-settlement calculation. C Assign a universal secondary-settlement limit irrespective of structural sensitivity. D Evaluate secondary compression over the relevant service period and check total as well as differential movements against project-specific tolerances.

Question 15 ప్రశ్న 15

Two columns on a common straight foundation line are 6 m apart. Their calculated vertical settlements are 45 mm and 15 mm, respectively. Assuming a linear differential profile and neglecting pre-existing elevation differences, what is the relative angular distortion between the columns?

A 1/100. B 1/120. C 1/300. D 1/200.

Question 16 ప్రశ్న 16

All monitoring points on a rigid raft record approximately 55 mm downward movement, with negligible differences in settlement across the raft. Which interpretation best describes the measurements?

A The raft has appreciable total settlement but little measured differential settlement or angular distortion. B The raft has zero total settlement because all points move together. C The raft must have failed in general shear because its movement is nearly uniform. D Angular distortion is 55/1 at every location regardless of the distance between observation points.

Question 17 ప్రశ్న 17

A project specifies a maximum allowable angular distortion of 1/500 between two supports spaced 5 m apart. Their measured settlements are 22 mm and 35 mm. What is the maximum allowed differential settlement, and does the observed condition satisfy the criterion?

A 13 mm maximum; the observed condition passes. B 10 mm maximum; the observed 13 mm difference fails. C 5 mm maximum; the observed condition passes. D 25 mm maximum; the observed condition passes.

Question 18 ప్రశ్న 18

A small plate-load test in sand produces a modest settlement, but a proposed large raft would additionally load a deep compressible clay stratum outside the small plate's principal stress-influence zone. Which engineering conclusion is appropriate?

A The raft's settlement must equal the measured plate settlement. B The plate result proves that long-term settlement of the clay is impossible. C The plate data should be supplemented by a stress-distribution and compressibility assessment of the deeper clay under the larger raft. D The raft's ultimate shear resistance determines the exact settlement without any soil stiffness information.

Question 19 ప్రశ్న 19

An irregular raft applies a uniform net pressure of 180 kPa. The estimated average vertical-stress influence factor within a 4 m thick compressible layer is 0.20, and the layer has mv = 4.0 x 10^-4 kPa^-1. Assuming one-dimensional compression with constant mv, what is the eventual settlement contribution from this layer?

A 28.8 mm. B 36.0 mm. C 72.0 mm. D 57.6 mm.

Question 20 ప్రశ్న 20

A clay deposit has initial vertical effective stress of 100 kPa and laboratory preconsolidation pressure of 250 kPa. A new foundation raises the representative effective stress to 200 kPa. Which conclusion is appropriate for an ideal one-dimensional compression analysis using a separate recompression index Cr and virgin-compression index Cc?

A The loading remains below preconsolidation pressure, so settlement is calculated on the recompression branch using Cr. B The soil must be treated as normally consolidated from the initial loading stage because total pressure increased. C The entire increment must use the virgin compression index Cc because the final stress exceeds the initial stress. D Settlement is exactly zero whenever the final stress remains below the preconsolidation pressure.

Question 21 ప్రశ్న 21

Groundwater lowering beneath a foundation increases effective stress within a saturated compressible clay layer, even though the building load remains unchanged. Which interpretation is most appropriate?

A Settlement is impossible unless the superstructure load also increases. B Reducing pore-water pressure always reduces the effective stress on the soil skeleton. C The effective-stress increase can initiate additional consolidation settlement, so the groundwater change must be considered in the foundation assessment. D The change can affect only sand and cannot influence a clay layer.

Question 22 ప్రశ్న 22

A footing applies gross contact pressure of 250 kPa at a founding depth where excavation removed soil exerting 40 kPa of overburden. Under the stated net-load approximation, the stress influence factor averaged across a 3 m thick clay layer is 0.25, and mv = 4.0 x 10^-4 kPa^-1. What primary settlement is predicted using S = mv DeltaSigma H?

A 52.5 mm. B 63.0 mm. C 75.0 mm. D 120.0 mm.

Question 23 ప్రశ్న 23

Monitoring shows that a foundation on organic clay has completed essentially all primary consolidation by the end of year 1, when total settlement is 60 mm. Under unchanged loading, it records 75 mm at the end of year 10; assume subsequent secondary settlement increases linearly with log10(time) from the same time origin. What total settlement is predicted at the end of year 100?

A 75 mm. B 105 mm. C 120 mm. D 90 mm.

Question 24 ప్రశ్న 24

A saturated clay specimen represents a soil layer of initial thickness H0 = 2.70 m and initial void ratio e0 = 0.90. Under one-dimensional compression, the final void ratio becomes ef = 0.72 without loss of soil solids or change in plan area. What settlement follows from the void-ratio change?

A 255.8 mm. B 180.0 mm. C 486.0 mm. D 324.0 mm.

Question 25 ప్రశ్న 25

Two adjacent foundation supports 10 m apart have predicted settlement components as follows: Support A has 20 mm immediate, 40 mm primary and 10 mm secondary; Support B has 15 mm immediate, 20 mm primary and 5 mm secondary. The project permits maximum angular distortion of 1/400. Assuming the relative settlement profile between supports is linear, what is the correct assessment?

A Both settle 70 mm, so there is no differential settlement. B A settles 70 mm and B settles 40 mm; angular distortion is 1/333 approximately, which fails the specified limit. C A settles 70 mm and B settles 40 mm; angular distortion is 1/500, which passes the specified limit. D The settlement difference is 10 mm and the condition necessarily passes.

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