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Correct answer is (a) COFFERDAM

To EXPLAIN I would say: The cofferdam is generally constructed at the SITE of WORK. The cofferdam should be reasonably watertight. It MAY either raised on the impervious soil or may be extended to impervious strata through pervious soils. It should be noted that absolute water tightness is not desired in a cofferdam.

The correct answer is (B) Cellular cofferdam

The best explanation: Cellular cofferdam consists of diaphragm CELLS or circular cells or modified circular cells or cloverleaf cells. In case of circular cofferdams with diaphragm cells, the series of ARCS are CONNECTED to straight cross wall. The radius of arcs is GENERALLY made equal to the distance between the cross-walls.

Correct choice is (a) Chemical GROUTING

To explain I would say: As the chemical grouting has been DEVELOPED recently, the precise information of its long-term after effects is not AVAILABLE. Hence it has yet not become an ESTABLISHED TECHNIQUE as the conventional grouting.

Right option is (b) Raymond STEP taper concrete pile

For explanation: Raymond step taper concrete pile consists of Steel sections of SUITABLE length. The bottom of the first shell to be driven is closed by a flat steel plate. The DIAMETER of pile increases in steps at the rate of 25 mm for each successive shell section.

Right answer is (c) Chemical grouting

To elaborate: In 1925, H.J. Joosten, a Dutch mining ENGINEER, ADOPTED for the first time the chemical grouting. He used concentrated SOLUTION of sodium silicate and calcium chloride as ELECTROLYTE. According to him, the chemical MUST be able to modify the properties of soil as desired or expected.

Right answer is (c) Double wall COFFERDAM

To EXPLAIN I would say: Double wall cofferdam was frequently used on the river Ohio in USA and hence, it derives its name as Ohio river type cofferdam. It is cheap and can be BUILT up rapidly l. It is suitable for hard bed where there is no PROBLEM of erosion. This type of cofferdam is unsuitable for deep water.

Right ANSWER is (a) Pumping

Easiest explanation: In pumping METHOD, the pumps are installed along the foundation trenches at suitable POINTS. The water gaining ACCESS to the trenches is pumped out. These pumps are portable so that it can be EASILY moved as and when required.

Correct ANSWER is (b) Hiley formula

Easy explanation: Above given formula is Hiley formula. This formula is widely used in determining the safe load on pile.

Where, E = EFFICIENCY of hammer.

K = COEFFICIENT of restitution.

Correct answer is (c) Steel

To ELABORATE: Steel is USUALLY in the FORM of a double skin of Steel PLATING and the hollow space in then filled with cement concrete. Due to its strength and DURABILITY it is found to be most suitable material.

The CORRECT answer is (a) Vacuum system

Explanation: The vacuum process is very much USEFUL and EFFECTIVE for inorganic and organic silts and very fine sand. But several weeks may be required to achieve CONSOLIDATION by this method.

Right option is (a) Mac ARTHUR pile

The explanation is: In Mac Arthur pile, a heavy steel CASING with a core is driven into the ground as SHOWN in given figure. When the desired depth is REACHED, the core is withdrawn and a CORRUGATED steel shell is placed in the casing.

Right choice is (d) PNEUMATIC caissons

The explanation is: The pneumatic caissons are adopted when the depth of water is more than 12 metres or so. The MAXIMUM depth of water upto which pneumatic caissons can be USED is limited from the CONSIDERATION of health of the workers.

The correct option is (a) Concrete cofferdam

Explanation: Concrete cofferdams are actually small concrete dams and they have been USED ECONOMICALLY on many Jobs. The FRAMEWORK usually consists of precast RCC PILES and sheets. The main disadvantage of a concrete cofferdam is that it is costly.

Right option is (a) Swage PILE

The explanation: In Swage pile, a precast CONCRETE plug of slight conical shape provided at the bottom of a steel shell. These piles are used for HARD SOIL or at places where it is desired to have a WATERTIGHT shell before concrete is placed in the Shell.

Right option is (d) Multi stage system

Best explanation: When the DEPTH of excavation EXCEEDS 5 M below the WATER table, the PROCESS of PROVIDING well Point is carried out in different stages known as Multi stage system.

The correct option is (a) Deep well pumps

To explain: In case of multistage SYSTEM of well points, the deep well pumps should be used when the INSTABILITY of the side slopes is EXPECTED. As deep well pumps are expensive, they are ADOPTED on important WORKS.

Right answer is (b) Box sheeting

To elaborate: The Box sheeting arrangement is adopted for loose SOIL. In this, the sheets are kept in position by LONGITUDINAL rows of WALES, usually 2 in numbers and then, the STRUTS are provided across the wales.

Correct option is (c) Suspended cofferdam

Best explanation: Suspended cofferdams are also known as the movable cofferdams. The suspended cofferdams may take up any FORMS. In one form, it consists of a hollow steel CYLINDER which can be used to PREPARE a temporary enclosed space for the CONSTRUCTION work.

Correct ANSWER is (b) Major Sander FORMULA

Explanation: Major Sander formula is the simplest form of pile driving formula using a factor of safety of 8. Where, R1 = safe LOAD on a pile in kg.

S = final SETTLEMENT of pile in cm.

The correct option is (a) Freezing process

The explanation: The freezing is a powerful versatile tool for foundation engineering for temporary ground support, groundwater control and structural underpinning. A PORTION of the slope is FROZEN and this POSITION act as a temporary Dam to support the SOIL and it prevents the earth slides.

Right CHOICE is (a) Riser

For explanation I WOULD say: A Riser is a vertical PIPE driven in the ground. The well point is provided at the bottom end of the riser. The diameter of the Riser is about 40 mm to 50 mm.

The correct choice is (b) Earth-fill cofferdam

Easy explanation: Earth dikes or Earth-fill cofferdams are limited to Shallow depth of WATER, say about 1200 MM to 1500 mm, with a low velocity of flow. It consists of an Earth BANK which is placed around the SITE to be enclosed.

Right ANSWER is (d) PRESSURE pile

Explanation: In Pressure pile, the compressed air is then admitted through the air Pipe and which is applied to RAISE the TUBE. Thus, the tube is lifted slightly and at the same time, the concrete is forced into the surrounding GROUND by compressed air.

The CORRECT OPTION is (d) FREEZING process

The explanation: In the freezing process method, the area surrounding the EXCAVATION is frozen and THUS a solid wall of frozen Earth is formed. The principle of ground freezing is the use of refrigeration to convert in-situ pore water to Ice.

Correct answer is (a) Wale

Explanation: RANGER or Wale is the NAME given to the piece of timber which transfers the load from the SHEETING to the Strut. This piece of timber also acts as a supporting member for BRACING.

Right CHOICE is (a) Well

Easy explanation: Well is provided with a cutting edge at the bottom so as to facilitate sinking. The shape of a well is GENERALLY decided by the requirements of the superstructure, vertical and horizontal forces on well, base of the pier or abutment, cost of sinking, CHANCES of tilting and SHIFTING during execution, ETC.

The correct answer is (C) Dike

To explain I would SAY: The materials commonly employed for the construction of dike are earth, ROCK and sand bags. The dike are generally employed for a short duration, PARTICULARLY to ENABLE the construction of a more durable cofferdam behind them.

The correct option is (c) Chemical GROUTING

For explanation I would say: In 1925, H.J. Joosten, a DUTCH mining engineer, adopted for the first time the chemical grouting. He used CONCENTRATED solution of sodium silicate and CALCIUM chloride as electrolyte.

The correct choice is (c) STATIC formulas

The best explanation: To determine Static formulas, the SAMPLES of soils through which piles are to be DRIVEN are tested in the laboratory and properties of different soils are studied in detail. These results from the laboratory TESTS are then used to determine the bearing capacity of a pile of a given length, shape and size.

Correct choice is (b) Simplex Alligator pile

Easy explanation: In Simplex Alligator jaw pile, the cast iron SHOE is PROVIDED by alligator jaw point. When CONCRETE is poured, the jaw opens and ALLOWS concrete to flow. In this TYPE of pile, the shoe does not remain in the ground.

The correct answer is (a) Sheeting

Explanation: The TERM SHEATHING is used to indicate vertical MEMBERS of timber in which directly resist PRESSURE from the side of a Trench.

Right choice is (d) Box caissons

For explanation: Box CAISSON is merely a variation of the Suspended type cofferdam. The box caissons MAY be built of reinforced concrete, steel or TIMBER. Condition for box caisson is that the depth of water is about 6 METERS to 8 meters.

Right ANSWER is (d) Rock-filled crib COFFERDAM

To explain: A crib is a box or a CELL open at the bottom and it essentially consists of a framework of horizontal timbers laid in alternate courses. The Rock-filled crib cofferdam have been employed with success on many IMPORTANT Jobs. The IDEAL set of conditions favourable for this type of cofferdam is the depth of water is about 10 meters to 20 m.

Correct answer is (b) Ritter formula

For EXPLANATION: Above given formula is Ritter formula. It is an important PILE driving dynamic formula. Where, R = ultimate load carrying capacity of pile in kg.

H = height of FREE fall of ram in case of drop hammer in CM.

S = final settlement of pile in cm.

Correct answer is (a) Load bearing pile

Explanation: Load bearing piles penetrate through the soft SOIL and their bottom rest on a hard bed. Thus, they are end bearing piles and ACT as a column or piers. The soft GROUND through which the piles pass also give some lateral support and thus increases the load CARRYING capacity of the bearing piles.

The correct choice is (a) VACUUM system

The explanation is: The vacuum PROCESS is very much useful and effective for inorganic and ORGANIC silts and very fine sand. But several weeks may be required to achieve CONSOLIDATION by this method.