MPPSC SES Civil key terms

The number of unknown reaction or internal force components exceeding those obtainable from static equilibrium alone. It equals unknowns minus available equilibrium equations, and determines whether compatibility methods are needed for analysis.

A diagram showing how a particular response, such as a reaction, shear, or bending moment at a fixed section, varies as a unit load moves across the structure. Used for moving load and bridge design.

A successive-approximation technique for analysing indeterminate frames and continuous beams. Fixed-end moments are released in stages using distribution factors and carry-over factors until unbalanced moments become negligible.

A design philosophy in which a structure is checked against collapse (ultimate limit state) and against serviceability criteria such as deflection and cracking. Partial safety factors are applied separately to loads and material strengths.

A multiplier applied to loads or material strengths to account for uncertainty and variability. In Indian limit state design, load factors typically range from 1.2 to 1.5, while material factors are 1.15 for steel and 1.5 for concrete.

The mass of water divided by the mass of cement in a concrete mix. It governs strength and durability: lower ratios give stronger, less permeable concrete, and codes cap it by exposure condition.

A simple workability test in which fresh concrete in a standard cone is allowed to subside after the mould is lifted. The measured vertical drop indicates consistency, though it is not suitable for very dry mixes.

The intergranular stress carried by the soil skeleton, equal to total stress minus pore water pressure. It controls shear strength, compressibility, and settlement in saturated soils.

The time-dependent reduction in volume of a saturated soil under sustained load, caused by gradual expulsion of pore water. It is analysed using void ratio versus log pressure curves and coefficient of consolidation.

A field test in which a split-spoon sampler is driven into the ground by a standard hammer, counting blows for each penetration interval. The resulting N-value is used for strength and settlement correlations.

Loss of shear strength in loose, saturated sandy soils during earthquake shaking, when cyclic loading raises pore pressure until effective stress becomes nearly zero. The ground then behaves like a fluid.

The maximum pressure a foundation soil can support without shear failure or excessive settlement. It is estimated from shear strength parameters and footing geometry, then divided by a factor of safety for allowable pressure.

An empirical formula relating open-channel velocity to hydraulic radius, bed slope, and a roughness coefficient n. It is widely used for designing canals, drains, and natural channels.

A flow condition at which the Froude number equals one and specific energy is minimum for a given discharge. It marks the boundary between subcritical and supercritical flow and is used in channel transitions and controls.

An abrupt transition from supercritical to subcritical flow, accompanied by turbulence and energy loss. It is deliberately used as an energy dissipator below spillways and weirs.

A plot of river discharge or stage against time at a given section. Its shape reflects rainfall pattern, catchment characteristics, and baseflow, and it forms the basis of flood estimation.

The direct runoff hydrograph produced by one unit of effective rainfall (typically 1 cm) falling uniformly over a catchment in a specified duration. It is scaled and superimposed to estimate larger storm responses.

The mass of dissolved oxygen consumed by microorganisms while oxidising organic matter in a water sample over a standard period, usually five days at 20 degrees Celsius. It indicates organic pollution load.

The oxygen equivalent of organic matter oxidised by a strong chemical oxidant under acidic conditions. It is measured in hours rather than days and includes matter resistant to biological breakdown.

A secondary biological treatment in which sewage is aerated with a dense microbial floc that absorbs and oxidises organic matter. Sludge is settled and partly recycled to maintain the biomass.

Gentle, prolonged stirring that encourages small destabilised particles to collide and clump into larger, settleable flocs after coagulant addition. It follows rapid mixing in a water treatment plant.

The reference speed adopted for geometric design of a road, such that all curves, gradients, and sight distances are consistent with it. It depends on terrain class and road category.

The transverse slope provided on a horizontal curve by raising the outer edge, so that centrifugal force is partly balanced by the weight component. Its value is limited by friction and comfort.

The cross slope given to a road surface, or to a shoulder, to drain rainwater quickly towards the edges. Its magnitude varies with surface type and rainfall intensity.

The California Bearing Ratio, expressing the resistance of a soil or pavement material to penetration by a standard plunger as a percentage of a standard value. It is used in flexible pavement thickness design.

A permanently established point whose reduced level is known with respect to a datum. It serves as the reference from which other levels are transferred during levelling surveys.

The elevation of a point above or below a chosen datum, obtained by adding or subtracting successive staff readings from a known benchmark. It is the standard output of a level survey.

An imaginary line on a map joining points of equal elevation. The spacing and shape of contours reveal slope steepness, ridges, valleys, and catchment boundaries.

A survey in which a series of connected lines is measured in length and direction, forming a framework of control points. Closing errors are adjusted to obtain coordinates of the stations.

Software and procedures for capturing, storing, analysing, and displaying spatially referenced data in layers. It links attribute tables to map features and supports overlay, buffering, and suitability analysis.

Acquisition of information about the Earth's surface without physical contact, using sensors on satellites or aircraft that record reflected or emitted electromagnetic radiation across selected wavelength bands.

A raster representation of ground surface elevation on a regular grid. It is used to derive slope, aspect, flow direction, and catchment boundaries in terrain and hydrological analysis.

A network scheduling technique that identifies the longest duration chain of dependent activities, thereby fixing the project duration. Activities on this chain have zero float and must not be delayed.

The spare time available to an activity without delaying the project or a later activity. Total float is measured along the network, while free float is the slack before the next activity begins.

A project control method comparing budgeted cost of work performed with actual cost and planned value. Derived indices reveal cost and schedule performance before completion.

The process of determining the unit rate of a construction item by summing material, labour, plant, and overhead costs, then adding contractor profit and applicable taxes. It underpins bill preparation.

A document listing measured quantities of each work item with descriptions and units, prepared from drawings. Tendered rates are applied to it to form the contract price.

The maximum resistance of a soil to shear stress, governed by friction between particles and cohesion or cementation. It is expressed through the Mohr-Coulomb parameters and is central to slope and foundation stability.