University of Washington

Department of Civil and Environmental Engineering

CEE 317

GeoSurveying

First Project

A Piling Construction Site

A high rise building is going to be constructed on the site assigned to you. The site has to be excavated to a suitable level and prepared for piling works. The foundation will consist of reinforced concrete pile caps on "bored piles". The project goals are to:

• Compute the amount of soil to be borrowed or disposed.
• Lay out pile locations.

To meet the above-mentioned goals, you will employ your knowledge of: total Station operation, Borrow-pit leveling, and traversing. Each group will be assigned a certain site with two control points. The project will be done in three phases:

Control Extension

Since it may not be possible to observe the whole site from one or two points, more horizontal and vertical control points are needed. A traverse around the site will be established and adjusted. A benchmark will be established only if needed. Traverse points are supposed to be relatively permanent; a sprinkler head is a good example. If such a point cannot be found, a mark should be carefully placed. Marks could be painted on asphalt or on wood hubs. A traverse of at least four points is required for horizontal control. The traverse is a closed polygon of measured distances and internal angles. After adjusting the traverse, precise coordinates of the three unknown points can be obtained, you will be given the coordinates of one control point. If a benchmark is needed, use the same technique you used in the leveling lab to establish it. There are two control points in each of the sites (1) and (2). When you do the adjustment, only one point is considered control and the other one is adjusted the same way the other points are adjusted. In site (1) point 36 is the one that is not supposed to be adjusted, in site (2), point A is the full control. The reason why you are given two control points is to compute the required azimuth to orient the traverse.

The fieldwork will proceed as follows: first decide where the three new points are needed so that control points surround the whole site, and mark the points. Then, measure the distances and the interior angles of the polygon. If your site is (1) or (2), you will also need to measure the angle between the line (20-36) and any of the traverse lines to obtain the azimuth of one of the sides, in site 3 the azimuth of the line A-B is given. Distances are measured using electronic instruments and do not need to be repeated. Angles will be measured in both phases, direct and reverse, the average is a single observation. Each angle will be measured three times, that is 12 readings per angle. The overall average and standard deviation is to be computed. When all the measurements are done, the traverse is adjusted and the coordinates are computed. That part will be explained in the lectures. For a field notebook example, refer to plate D-5 in the textbook.

What to report: The adjusted coordinates of the three points, the total misclosure, measured angles, and the length of the traverse sides.

Equipment needed for this part: total station, Prism, two tripods, and plumb line.

Earthwork

The final working elevation is not the existing elevation. There will be a need to backfill some areas and to cut some others. Before the construction of piles, the site must be leveled at a suitable elevation to allow safe operation of heavy equipment. In order to compute the volumes, the borrow-pit method will be used. Imagine that you will cover the site with a grid of 30 ft spacing. Place marks along two or three of the edges at 30 ft intervals, and measure the elevation at the corners of the grid. It may be a good idea if more than one level or more than a rod is used. After all the elevations are computed, calculate the final amount of cut or fill.

Equipment needed for this part: Level, leveling rod(s), a tape measure, pins, and a tripod(s).

Pile Locations

A number of pile shafts need to be located before the machine can start drilling. The radial method will be used to locate pile shafts, knowing the angle and the distance to the point, a total station can be used to locate the point. Before you get out to locate the piles, you should compute the required distances and angles. That can be done in the week before that task is scheduled. After all pile locations are marked with steel pins, use the tape to compare the distance between the pile shafts and compare them to the theoretical value. There will be no Field notebook recording for this section. Use a table, which includes the computed angles and distances to the piles.

A fatal mistake that you should avoid is locating the centers of the pile caps. You are asked to locate the centers of the piles not the pile caps.

Equipment needed for this part: a total station, tripod, plumb line, a prism pole, marking pins, and a prism

Job Assignment

 Group Site Control points Final Site Elevation 1st week 2nd week 3rd week 1 1 36&20 98 ft Pile locations Traverse Earthwork 2 2 36&20 98 ft Pile locations Earthwork Traverse 3 3 A&B 75 ft Pile locations Traverse Earthwork 4 1 36&20 98 ft Earthwork Pile locations Traverse 5 2 36&20 98 ft Earthwork Pile locations Traverse

Site Description

Site (1): the grass area between the fountain and Stevens Way.

Site (2): The area in Sylvan Theater Bounded by the points A, B, C, and D.

Site (3): The grass area around Rainer Vesta, south of point 20. The site extends for 400 ft south of point 20 along Rainer Vesta.

Control Point Coordinates (ft)

 Point X Y Z 36 636,980 241,895 112.05 20 637,206 241,387 83.27 A 1000 1000 100 B not given 1000 not given

Pile Layout Information

1- Pile cap design

Each pile cap consists of four piles. Pile diameter is 3 ft. Pile spacing is 6 ft, which is the distance from each pile axes to the other along the edges of the cap. You will be given the location of the center of the cap, and the orientation of the axis A, and B

2- Cap Locations

Area (1): Three pile caps, a total of 12 piles. Axis (A) is Parallel to the line 36-20. Axis B is Perpendicular to the line 36-20

 Cap Number Axis B Axis A 1 200 ft from 36 On the line 20-36 2 150 ft from 36 10 ft from the line 20-36, east. 3 300 ft from 36 10ft from the line 20-36, west.

Area (2): Five pile caps, a total of 20 piles. Axis (B) is parallel to the line AB, which is parallel to the (X) axis. The coordinates of the cap centers are as follows:

 Cap Number X Y 1 1060 1070 2 1040 1040 3 1080 1050 4 1040 1100 5 1080 1100

Area (3): Three pile caps, a total of 12 piles. Axis (A) is parallel to the line 20-36. Axis (B) is perpendicular to 36-20

 Cap Number Axis B Axis A 1 50 ft south of 20 30 ft from the line 20-36 west. 2 50 ft south of 20 30 ft from the line 20-36, east. 3 100 ft south of 20 30 ft from the line 20-36, west.

Data Preparation and Field Work

To locate the piles in the field you need to know: an angle from a line, and a distance from a point. In other words, you need to know the polar coordinates of the pile axis from the point of observation. For example, If you are occupying point (36), then you need to know the angle from line 36-20 and the distance from 36 to the pile axis. In the field, you aim at 20 from 36, measure the angle you computed, and let somebody hold a prism and move along your line of sight until you read the required distance. For that task, you will not use a tripod for the prism, but you will use a mobile prism holder.

Since you are given the distance along the reference line, 36-20 for example, and a perpendicular distance to the pile axis, you should be able to compute the angle and distance you need for each pile. To save time, compute the angles and distances you need before the lab. There is no field notebook work required for that part.

What to Report

As a check, use a tape to measure the distances between all the pile axes in each pile cap. Compare the distances to the theoretical values.

What to Submit

A lab report per group, which describes in details the project objectives, the survey, plan, data acquisition, adjustments, problems, and results. A conclusion is an optional section.