ADVANCED SURVEYING (S-II) - WordPress

ADVANCED SURVEYING(S-II)(LAB)KISHANGANJ COLLEGE OF ENGINEERING AND TECHNOLOGY, KISHANGANJDEPARTMENT OF CIVIL ENGINEERING.

ADVANCED SURVEYING (S-II) LABDEPARTMENT OF CIVIL ENGINEERINGExperiment No- 1Aim: Determination of the Multiplying and additive constant of givenTacheometer.Apparatus: A tacheometer with tripod, tape, levelling staff, wooden pegs,ranging rods etc.Figure:Formulae:When the line of sight is horizontal, thenD KS cWhere,D Horizontal distance between instrument station and staff station.K Multiplying constant of a tacheometerS Staff intersect i.e. difference between top and bottom stadia hairreading.When line of sight is inclined and staff vertical then:D KS cos2 q c cosqWhere,D Horizontal distance between instrument station and staff station.K Multiplying constant of a tacheometerS Staff intersect i.e. difference between top and bottom stadia hairreading.q The inclination of the line of collimation to the horizontal.c The additive constant of the tacheometer.Theory:PRINCIPLE OF STADIA METHODThe stadia method is based on the principle that the ratio ofperpendicular to the base is Constant in similar isosceles triangles. In fig lettwo rays OA and OB be equally inclined to the central ray OC. Let A2B2,A1B1 and AB be staff intercepts.Evidently2

ADVANCED SURVEYING (S-II) LABDEPARTMENT OF CIVIL ENGINEERINGDetermination of Constant k and C:Procedure:peg.1) Select an instrument station A on a fairly levelled ground and fix a2) Do the temporary adjustment over A.3) With vertical circle to the left of the observer and reading 00000’00”bisect staff held at 10m, 20m, and 30m from A along straight line.4) Note down the staff reading against top and bottom stadia hair onstaff held at 10m, 20, 30m from A.5) In case of inclined line of sight the same procedure as stated above isfollowed step by step with a vertical angle of 05000’00” in the vertical circleof the theodolite. In this case, the vertical circle is held to the left of theobserver and with the reading 05000’00” in the circle the staff is bisected at10m, 20m, and 30m from A along straight but inclination line of collimation.3

ADVANCED SURVEYING (S-II) LABDEPARTMENT OF CIVIL ENGINEERINGCalculation:D Ks cFor three staff stations,D1 Ks1 c ------- (1)D2 Ks2 c ------- (2)D3 Ks3 c ------- (3)As ; s1, s2, s3 can be known solving (1) &(2), (2) & (3) , (1) & (3) to get 3 values ofm & c ,then average of three values is required answer.D Ks cos2 q c cosqFor, three station the equations are;D1 Ks1 cos2 q1 C cosq1 ------- (1)D2 Ks2 cos2 q2 C cosq2------- (2)D3 Ks3 cos2 q3 C cosq3------- (3)As ; s1, s2, s3 can be known solving (1) &(2), (2) & (3) , (1) & (3) to get 3 values ofK & C ,then average of three values is required answer.Result: a) For horizontal line of collimation;1) The additive constant ‘c’ for a given tacheometer is found out to be --------2) The multiplying constant ‘m’ for a given tacheometer is found to be --------b) For inclination line of collimation;1) The additive constant ‘c’ for a given tacheometer is found out to be ---------2) The multiplying constant ‘k’ for a given tacheometer is found to be ---------4

ADVANCED SURVEYING (S-II) LABDEPARTMENT OF CIVIL ENGINEERINGExperiment No-2Aim: Determination of Elevation of points by Tacheomentric surveying.Apparatus: A tacheometer with tripod, tape, leveling staff, wooden pegs,ranging rods etc.Figure:Formulae:When line of sight is inclined and staff vertical then:D KSCos2ϴ CSin ϴWhere,K Multiplying constant 100C Additive constantS Staff intercept.V Vertical distance measured from horizontal line of straightCentral stadia hair reading on staff.H Central stadia hair reading on staff.ϴ vertical angleTheory:- The Tacheometer is an instrument which is generally used todetermine the horizontal as well as vertical distance . It can also be used todetermine the elevation of various points which cannot be determined byordinary levelling. When one of the sight is horizontal and staff held verticalthen the RLs of staff station can be determined as we determine in ordinarylevelling .But if the staff station is below or above the line of collimation thenthe elevation or depression of such point can be determined by calculatingvertical distances from instrument axis to the central hair reading andtaking the angle of elevation or depression made by line of sight to theinstrument made by line of sight to the instrument axis.5

ADVANCED SURVEYING (S-II) LABDEPARTMENT OF CIVIL ENGINEERINGProcedure:1) Set up the instrument in such a way that all the point should bevisible from the instrument station.2) Carryout the temporary adjustment and set vernier zero readingmaking line of sight horizontal.3) Take the first staff reading on Benchmark and determine height ofinstrument.4) Then sight the telescope towards the staff station whose R.Ls are tobe calculated. Measure the angle on vernier if line of sight is inclinedupward or downward and also note the three crosshair readings.5) Determine the R.Ls of various points by calculating the verticaldistance.Calculation:D KSCos2ϴ CSin ϴ1) For ground floor:V1 (K1S1sin2ϴ)/2 C sin ϴR.L of ground floor RL of BM h V1-h1Result:The RLs of Various points are found as follows.6

ADVANCED SURVEYING (S-II) LABDEPARTMENT OF CIVIL ENGINEERINGExperiment No- 3Aim: - Setting out of simple circular curve by offsets from chord producedmethod.Problem Two straight intersect at chainage (30 10), the deflectionangle being 44º. Calculate the necessary data for laying out a curve by themethod of offsets from the chord produced. The degree of the curve being 7º.The peg interval being equal to 20meters.Procedure for setting out of curve1) Locate the tangent points T1 and T2 on the straights AB and CB.2) Cut T1D1 equal to the length of the first sub chord (C1) alreadycalculated along the tangent T1B.3) With T1 as centre and T1D1 radius, swing the chain or tape suchthat the arc D1D calculated offset O1, thus fixing the first point D on thecurve.4) Keep the chain along T1D and pull it straight in the forwarddirection of T1D until the length DE1 becomes equal to second C2 (i.e thelength of normal chord).5) With D as centre and DE1 as radius, swing the chain such that thearc E1E calculated offset O2, thus fixing the second point E on the curve.6) continue the process repeating the point (d) and (e) until that endthe curve is reached. The last point so fixed must coincide with thepreviously located points T2 (the last curve tangent point) if not, find out the7

ADVANCED SURVEYING (S-II) LABDEPARTMENT OF CIVIL ENGINEERINGclosing error. If it is small (say within 2m) it should be distributed to all thepoints by moving them sideways by an amount proportional to the square oftheir distances from the point T1, otherwise the whole curve should be set outagain.Solution: - Given degree of curve ,D 7ºDeflection angle, Ø 42ºRadius of curve R245.55mTangent length R Tan Ø/2 245.55 0.4040 99.20mLength of Curve Chainage at the point of intersection (30 10) chains 30 20 10 610mChainage at 1st tangent point 610.00-99.20 510.80m (25 10.80) chainsChainage at end of curve or second tangent point 510.80 188.57 699.37m(34 19.37) chainsNote:-20m chain used.Length of 1st Sub- chord (26 00)-(25 10.80) 9.20mNumber of full chord 34-26 8Length of last sub-chord (34 19.37)-(34 00) 19.37mCheck: Length of Curve 1ST sub chord Full chord last sub chord 9.20 8 20 19.37 188.57mNow from equation length of first offset,Length of second offset,Offsets from O3 to O8 are given by equationLast offset,Results:- By offsets from chord produced method the simple circular curvewas plotted on the ground.8

ADVANCED SURVEYING (S-II) LAB DEPARTMENT OF CIVIL ENGINEERING 3 Determination of Constant k and C: Procedure: 1) Select an instrument station A on a fairly levelled ground and fix a peg. 2) Do the