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Question 1
ప్రశ్న 1
A surveyor records the orientation of an inclined bedding plane exposed in a quarry. What is the geological strike of that plane?
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Explanation:
Strike describes the orientation of a horizontal line contained in a geological plane. It is usually recorded as a compass bearing or azimuth. The dip direction is perpendicular to the strike direction for a planar surface. Strike and dip together specify the attitude of bedding, faults or joints. Engineers use these measurements to examine the orientation of potential sliding surfaces and seepage pathways.
వివరణ:
Question 2
ప్రశ్న 2
A planar bedding surface has an east-west strike and a true dip of 35 degrees toward the north. Which description of its orientation is correct?
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Explanation:
True dip is the maximum inclination of a plane below the horizontal. Its direction is perpendicular to the strike line. An east-west strike permits a true dip toward either north or south, depending on the actual plane orientation. The problem explicitly states that the plane dips toward the north. The correct interpretation is therefore a 35-degree downward inclination toward the north.
వివరణ:
Question 3
ప్రశ్న 3
A road-cut section intersects an inclined bed along a direction oblique to its strike. Which comparison of apparent dip and true dip is valid for a nonvertical plane?
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Explanation:
True dip is the steepest inclination of the plane. An oblique vertical section normally reveals a smaller inclination known as apparent dip. The apparent dip becomes equal to the true dip in a section parallel to the true-dip direction. A vertical section parallel to strike gives zero apparent dip for an ordinary inclined plane. The distinction matters when interpreting beds exposed in obliquely oriented tunnels and cuttings.
వివరణ:
Question 4
ప్రశ్న 4
A rock bed has true dip 45 degrees. A vertical section is taken in a direction making 30 degrees with the STRIKE of the bed. Using tan(apparent dip) = tan(true dip) x sin(30 degrees), with tan(45 degrees) = 1 and sin(30 degrees) = 0.5, what is the apparent dip?
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Explanation:
The section direction makes a specified angle of 30 degrees with the strike. The given formula relates the tangent of apparent dip to true dip and this angle. Thus tan(apparent dip) = 1(0.5) = 0.5. Taking the inverse tangent gives an apparent dip of approximately 26.6 degrees. This value is smaller than the true dip of 45 degrees, as expected for an oblique section.
వివరణ:
Question 5
ప్రశ్న 5
A planned geological cross-section runs exactly parallel to the measured strike of a uniformly inclined bedding plane. What dip would that section show, assuming the plane is not vertical?
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Explanation:
A strike line is horizontal by definition. A vertical section parallel to strike cuts an inclined plane along a horizontal line. The inclination of that intersection line is therefore zero. This is the limiting case of the apparent-dip relationship when the section makes zero angle with strike. A zero apparent dip in such a section does not mean the bedding plane itself is horizontal.
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Question 6
ప్రశ్న 6
A normally ordered sequence of sedimentary strata forms an upward-arching fold, with both limbs generally dipping away from its central region. Which interpretation is correct?
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Explanation:
An anticline is a fold whose limbs commonly dip away from the central axial region. In a normally ordered, nonoverturned sedimentary succession, older strata occur toward its core. The geometry of folds can influence the depths and orientations of different rock layers encountered in excavation. A fold is a bending of strata and does not by itself prove fault displacement. Establishing stratigraphic younging direction is important where folding is complex or beds are overturned.
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Question 7
ప్రశ్న 7
A tunnel investigation finds a downward-curving fold in sedimentary strata whose limbs generally dip toward the centre. In a nonoverturned sequence, which identification and age relationship are expected?
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Explanation:
A syncline is a downward-curving fold with limbs that commonly dip toward its axial region. In a nonoverturned sedimentary sequence, younger beds generally occur toward the core. Fold geometry can control the position of alternating strong and weak strata along the tunnel alignment. Geological mapping should identify both bedding attitude and stratigraphic order. The nature of the fold cannot be established from a single isolated dip measurement alone.
వివరణ:
Question 8
ప్రశ్న 8
In a tightly folded sedimentary sequence, both limbs dip in the same compass direction, but geological younging indicators show that one limb is inverted. Which fold description is most appropriate?
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Explanation:
An overturned fold develops when deformation rotates one limb beyond the vertical attitude. Both limbs can then dip in the same general compass direction. One limb is inverted relative to the original stratigraphic order. Way-up or younging indicators help identify the inverted limb. This distinction is important when predicting the repetition and orientation of rock units beneath an engineering site.
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Question 9
ప్రశ్న 9
A tunnel route is being considered through a strongly folded formation containing competent sandstone and weak shale beds. Which approach best addresses the structural-geology risk?
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Explanation:
Folded rock masses may contain sharp changes in bedding orientation over short distances. Deformation near hinges can be associated with fractures or localized damage, although the extent varies by site. Alternating sandstone and shale may also respond differently to excavation and groundwater. Mapping fold geometry and discontinuities helps locate potentially unfavorable zones. Tunnel alignment and support should be chosen from observed geological and geotechnical conditions.
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Question 10
ప్రశ్న 10
Two mapped rock masses contain fractures. Across fracture X, a marker bed is demonstrably displaced; across fracture Y, no measurable displacement is found. Which classification is most appropriate on the supplied evidence?
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Explanation:
A fault is a fracture or zone of fractures showing relative displacement of rock blocks. A joint is a fracture across which significant shear displacement is not observed. The offset marker bed establishes fault displacement at X. The lack of measurable displacement is consistent with a joint at Y, although very small movements may escape detection. Both types of discontinuity can influence stability and groundwater flow.
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Question 11
ప్రశ్న 11
Along an inclined fault plane, the hanging-wall block has moved downward relative to the footwall block. Which fault type is indicated?
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Explanation:
The hanging wall is the rock block lying above an inclined fault plane. The footwall lies below that plane. A normal fault is identified when the hanging wall moves downward relative to the footwall. Normal faulting is commonly associated with crustal extension. The fault zone may contain fractured or altered material that requires separate foundation and excavation assessment.
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Question 12
ప్రశ్న 12
A mapped inclined fault places the hanging-wall block higher relative to the footwall following displacement. Which interpretation is correct?
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Explanation:
A reverse fault involves upward movement of the hanging wall relative to the footwall. It is commonly linked to compressional tectonic deformation. A reverse fault with a comparatively low dip is commonly called a thrust fault. Such structures may duplicate strata and juxtapose contrasting rock units. Engineering investigations should establish fault-zone geometry and condition rather than infer bearing capacity solely from fault classification.
వివరణ:
Question 13
ప్రశ్న 13
A nearly vertical fault shows predominantly horizontal movement parallel to its strike, with little vertical separation. Which designation is most appropriate?
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Explanation:
Strike-slip faulting involves movement predominantly parallel to the strike of the fault. The relative displacement is therefore mainly horizontal along the fault trace. Such faults differ from normal and reverse faults, whose characteristic displacement is predominantly along the dip direction. Some natural faults also combine strike-slip and dip-slip components. The correct classification depends on the measured direction of relative movement.
వివరణ:
Question 14
ప్రశ్న 14
In a simplified vertical cross-section, a block has undergone 10 m of PURE DIP-SLIP displacement along a fault plane dipping at 60 degrees to the horizontal. Take sin(60 degrees) = 0.866 and cos(60 degrees) = 0.500. What are the vertical and horizontal components of this movement, respectively?
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Explanation:
The displacement is stated to lie within the dip direction of the inclined fault plane. Its vertical component is the movement magnitude multiplied by the sine of the dip angle. This gives 10(0.866) = 8.66 m. The horizontal component is 10(0.500) = 5.00 m. These components refer to the specified displacement vector and are not automatically the apparent separation of an inclined marker bed.
వివరణ:
Question 15
ప్రశ్న 15
A proposed dam abutment excavation exposes a broad fault zone containing crushed rock fragments and clay-rich, finely ground material. Which interpretation is most appropriate?
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Explanation:
Fault movement can fracture and crush rock along a localized zone. Coarser broken fragments are commonly described as fault breccia, while fine-grained crushed material may form fault gouge. These materials can differ substantially from the strength and deformability of adjacent intact rock. The fault zone may also have complex permeability due to fractures and fine-grained infilling. Detailed mapping, testing and suitable stabilization or seepage treatment may be needed.
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Question 16
ప్రశ్న 16
A fault crosses a proposed underground water-conveyance tunnel. Which statement about groundwater movement along the fault is most defensible?
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Explanation:
Faulting may create open or connected fractures that promote groundwater flow. Fine-grained gouge or mineralized infilling may instead reduce permeability in parts of a fault zone. The net hydraulic behavior depends on the three-dimensional structure and the contrast with the surrounding rock. Consequently, neither high permeability nor complete sealing should be assumed solely from the presence of a fault. Site-specific hydrogeological investigation is needed for tunnel inflow and water-pressure assessment.
వివరణ:
Question 17
ప్రశ్న 17
A rock mass contains three families of approximately parallel fractures, each family having a different orientation and no demonstrable shear displacement along most surfaces. What is the best structural-geology description?
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Explanation:
Joints commonly occur in sets with similar orientations. Several differently oriented joint sets may intersect one another. Their intersections can subdivide a rock mass into blocks or wedges. The stability of a given block depends on persistence, orientation, shear resistance, confinement and support conditions. Mapping joint sets is therefore central to assessing rock cuts and tunnel roofs.
వివరణ:
Question 18
ప్రశ్న 18
Two otherwise similar rock masses have joint spacings of 0.20 m and 2.0 m within a major joint set. Which conclusion about joint spacing and persistence is most accurate?
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Explanation:
Joint spacing describes the distance between adjacent discontinuities in a set, conventionally measured perpendicular to their planes. Closer spacing tends to subdivide a rock mass into smaller blocks. Persistence describes the continuity or extent of an individual discontinuity. Longer persistent discontinuities can permit larger connected weakness surfaces than short discontinuous joints. These geometric characteristics should be considered along with joint strength, infill and groundwater conditions.
వివరణ:
Question 19
ప్రశ్న 19
A highway cutting exposes thinly bedded sandstone and shale, with open separation along some bedding surfaces. Which engineering assessment is most appropriate?
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Explanation:
Bedding planes are the interfaces between successive sedimentary layers. These surfaces may have lower strength than the intact rock, especially if clay-rich or weathered. Bedding partings can also influence directional groundwater flow. Their orientation relative to a cut slope determines whether they could become daylighting release surfaces. Engineering assessment should therefore examine bedding alongside joints and faults.
వివరణ:
Question 20
ప్రశ్న 20
A rock cut has a slope face dipping 55 degrees toward due east. A persistent planar joint also dips due east at 35 degrees, and its effective friction angle is taken as 28 degrees with negligible cohesion for an initial kinematic check. Which conclusion is justified by the given angles alone?
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Explanation:
The joint and the slope face dip toward the same azimuth. The joint dip of 35 degrees is lower than the slope-face dip of 55 degrees, so the plane can daylight. Its dip is also greater than the stated friction angle of 28 degrees. These are important preliminary conditions for potential sliding on a persistent plane. Actual stability additionally depends on block geometry, release surfaces, groundwater pressure and other resisting forces.
వివరణ:
Question 21
ప్రశ్న 21
A rock slope contains two persistent joint sets whose planes intersect along a line that emerges outward through the slope face. Which potential instability should be specifically investigated?
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Explanation:
Two intersecting discontinuity planes can bound a rock wedge. The line of intersection is a possible direction of wedge movement. If the intersection daylights in the slope and the resisting shear forces are insufficient, sliding may occur. The joint conditions and groundwater pressure can substantially influence stability. A kinematic assessment followed by an appropriate force-based analysis helps determine the actual risk.
వివరణ:
Question 22
ప్రశ్న 22
At a road excavation, steeply tilted and eroded older sedimentary beds are overlain by nearly horizontal younger sedimentary layers. Which geological contact is most likely present?
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Explanation:
An angular unconformity separates younger strata from older strata having a different bedding orientation. The older beds were typically tilted or folded before erosion exposed a truncation surface. Younger sediments were subsequently deposited above that surface. The contact marks a break in the geological record and may coincide with weathered or mechanically variable material. Its geometry can affect foundation excavation and groundwater flow along the contact.
వివరణ:
Question 23
ప్రశ్న 23
An investigation records two different contacts. Contact X is an erosional surface separating older and younger PARALLEL sedimentary beds; contact Y is sedimentary rock resting on eroded crystalline granite. Which matching is correct?
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Explanation:
A disconformity represents a break or erosional surface between sedimentary strata that remain essentially parallel. A nonconformity occurs where sedimentary rocks overlie an eroded igneous or metamorphic basement. Contact X fits the first definition because both adjoining sequences are parallel sedimentary layers. Contact Y fits the second definition because sediments overlie granite. Identifying the contact helps assess possible weathering, variable rock conditions and seepage along the boundary.
వివరణ:
Question 24
ప్రశ్న 24
Mapping beneath a proposed concrete gravity dam reveals persistent, water-bearing joints and a weathered seam near the upstream foundation contact. Which engineering response is most appropriate?
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Explanation:
Water-bearing discontinuities can transmit seepage through or beneath a dam foundation. Pore-water and uplift pressures may influence sliding and overturning stability. A weathered seam may also have reduced shear resistance and deformability different from the host rock. Detailed geological mapping and permeability investigation guide the selection of treatment measures. Any grouting or drainage provisions should be designed and checked for the actual foundation conditions.
వివరణ:
Question 25
ప్రశ్న 25
A planned tunnel crosses an inclined sedimentary formation, a mapped fault zone and several joint sets. Which investigation and construction-planning approach makes best use of structural-geology information?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
A tunnel intersects discontinuities whose orientations vary with the geological structure and tunnel alignment. Persistent joints and bedding surfaces may form unstable blocks or wedges around the excavation. Fault zones can contain crushed material and locally unusual groundwater pressures or inflow. Structural mapping and subsurface investigation support prediction of these changes along the route. Excavation sequence and support measures should respond to the identified ground conditions rather than a single average rock property.
వివరణ:
Answer Key సమాధానాల పట్టిక
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Question 1 ప్రశ్న 1Answer: B. The compass direction of a horizontal line lying within the inclined plane. సమాధానం: B.
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Question 2 ప్రశ్న 2Answer: A. The steepest downward direction on the plane is north, at right angles to its strike. సమాధానం: A.
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Question 3 ప్రశ్న 3Answer: D. Apparent dip is no greater than true dip; it equals true dip when the vertical section is parallel to the true-dip direction. సమాధానం: D.
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Question 4 ప్రశ్న 4Answer: C. Approximately 26.6 degrees. సమాధానం: C.
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Question 5 ప్రశ్న 5Answer: B. Zero apparent dip, because the line of intersection is horizontal. సమాధానం: B.
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Question 6 ప్రశ్న 6Answer: A. It is an anticline, typically exposing older strata near the core. సమాధానం: A.
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Question 7 ప్రశ్న 7Answer: C. A syncline with younger strata generally toward the core. సమాధానం: C.
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Question 8 ప్రశ్న 8Answer: D. An overturned fold with one limb inverted relative to its normal stratigraphic order. సమాధానం: D.
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Question 9 ప్రశ్న 9Answer: B. Map bedding, fold hinges and any associated fracturing to predict changes in rock quality, seepage and excavation support needs. సమాధానం: B.
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Question 10 ప్రశ్న 10Answer: A. X is a fault and Y may be a joint. సమాధానం: A.
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Question 11 ప్రశ్న 11Answer: C. Normal fault. సమాధానం: C.
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Question 12 ప్రశ్న 12Answer: D. It is a reverse fault; a low-angle example is commonly termed a thrust fault. సమాధానం: D.
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Question 13 ప్రశ్న 13Answer: B. Strike-slip fault. సమాధానం: B.
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Question 14 ప్రశ్న 14Answer: C. 8.66 m and 5.00 m. సమాధానం: C.
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Question 15 ప్రశ్న 15Answer: A. Fault breccia and gouge may have properties markedly different from intact host rock and require focused investigation and possible treatment. సమాధానం: A.
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Question 16 ప్రశ్న 16Answer: D. A fault zone can act as a conduit, a barrier or a combination, depending on its fractures, infill and connectivity. సమాధానం: D.
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Question 17 ప్రశ్న 17Answer: B. Three joint sets whose intersections may define removable rock blocks or wedges. సమాధానం: B.
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Question 18 ప్రశ్న 18Answer: C. Closer joint spacing generally produces smaller blocks, while persistence governs the extent of individual discontinuity surfaces. సమాధానం: C.
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Question 19 ప్రశ్న 19Answer: A. Bedding planes can act as structural discontinuities, and their orientation, condition and continuity may influence sliding and groundwater movement. సమాధానం: A.
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Question 20 ప్రశ్న 20Answer: D. The joint can daylight and satisfies basic orientation and friction-angle conditions for potential planar sliding, but complete stability assessment still needs further data. సమాధానం: D.
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Question 21 ప్రశ్న 21Answer: B. Wedge sliding along the line of intersection, subject to the intersection orientation, strength and groundwater conditions. సమాధానం: B.
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Question 22 ప్రశ్న 22Answer: C. An angular unconformity recording deformation and erosion before younger deposition. సమాధానం: C.
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Question 23 ప్రశ్న 23Answer: A. X is a disconformity; Y is a nonconformity. సమాధానం: A.
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Question 24 ప్రశ్న 24Answer: D. Investigate the geometry and hydraulic connectivity of discontinuities, then assess suitable foundation treatment, cutoff or grouting, drainage and uplift control. సమాధానం: D.
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Question 25 ప్రశ్న 25Answer: B. Map the strike, dip, spacing, persistence and condition of discontinuities; investigate the fault and groundwater; and adapt alignment and support to the predicted zones. సమాధానం: B.