AutoCAD Civil 3D 2008

Transcription

1 AutoCAD Civil 3D 2008 Pump It Up All the Way to the Last Sheet! Dave Young S4-2 Course Summary: Pressure pipes such as water and force mains are simple to design. But when it comes to putting them on paper, the process can be quite tedious. Moreover, most users don t need the level of precision and control that Civil 3D provides for storm and sewer pipes. This session provides an alternative method for creating down-and-dirty force main or water line construction documents. Attendees will also see how the power of the upgraded Plan and Production Tools can generate plan and profile sheets for the entire job in just a few minutes. This session is for any Civil 3D 2008 user who needs to quickly produce a pretty picture of what lies just under the surface. Instructor: Dave got started in the civil world holding the dumb end of the chain, but was soon running survey crews. From there, he switched over to a CAD Manager position and then to IT Manager, but always remained with a civil or engineering company until recently. His computer science degree and IT background have helped him along the way with customizing and implementing unique solutions for more than 12 years. Although his family still doesn t know how to explain what he does, Dave s role at Repro Products is to help companies with their Autodesk training and implementation needs.

2 Pressure Pipes Why they can be considered just a pretty picture Gravity is often good thing. It keeps our feet firmly planted on the ground and makes apples fall from trees. Gravity lines, such as storm and sanitary sewer, follow Sir Isaac Newton s Universal Law of Gravitation, which simply states that stuff flows downhill. From this, one can infer that stuff does not flow uphill on its own and that it does not flow if there is no down. Because of this, gravity lines must be designed with minimum grades to ensure flow, as well as maximum grades to ensure that it does not flow too fast. Additionally, the powers that be have instituted maximum lengths for gravity lines that must be followed. Civil 3D provides wonderful tools for designing gravity flow systems that will check for all of these things, as well as minimum and maximum depths of ground cover. Most of the time, gravity is a friend of a civil engineer and project owner. Gravity lines are relatively cheap to build. Getting stuff to flow uphill is another matter. In this case, gravity is not the friend of the civil engineer, as it requires the use of mechanical pumps to overcome gravity. The design of pump stations and the hydraulic calculations for a pressure system are far beyond the scope of this course and are not necessary for the placement of the pressure pipes. In fact, the vertical displacement (head) of the system often cannot be calculated until after the line has been laid out and the pipe profile created to determine the minimum and maximum elevation along the pressure pipe. These numbers are then entered into the hydraulic calculations to arrive at the final pump and pipe sizes. Because there is a mechanical force driving a pressure system, pipe grade is immaterial in most cases, because stuff can now flow uphill. Additionally, straight segments of pipe are not required, as the pumps will push the stuff through any grade change in the pipe system. Nor are structures required for grade or direction changes in the system. This allows a pressure pipe system to more closely follow the existing surface along the project. In the case of Pressure Pipes, Civil 3D offers little assistance as of yet. However, all is not lost. With a little creative use of the Alignment and Profile objects, a pressure pipe system can be very rapidly designed. Sprinkle in a few structures to serve as Air and Vacuum Release (A&V) valves and you will find that Civil 3D makes drawing pressure pipes child s play. Before getting started with the concept of using alignment and profiles to draw a pressure pipe system and using the Plan Production Tools to generate the corresponding sheets, take a look at the outline of the steps listed below. Each will be expanded on in this handout. Pump it up 1. Create an Alignment representing the horizontal layout of the pressure pipe 2

3 2. Create a Profile representing the vertical layout of the pressure pipe a. Draw the profile at ground level using Tangents with Curves, selecting the PVIs. b. Set the beginning and ending elevations c. Adjust the profile tangents and curves to match existing grade. d. Check for minimum curve radii e. Lower the line to its proper elevation 3. Place structures representing A&V valves a. Locate high points of the profile i. Use high point labels on the Profile ii. Use high point labels on the Alignment (new for 2009) b. Place structures in plan view at the high points c. Draw (and label) structures in profile view All the way to the last sheet! 1. Use Plan Production Tools to lay out sheets a. Create View Frames b. Create Sheets 2. Annotate Sheets 3. Create sheet index drawing Since this class is intended for the intermediate to advanced Civil 3D user, only the concept of drawing pressure pipes using alignments and profiles will be explained, rather than the actual button clicks needed to produce a set of construction documents. 3

4 Using Road tools to design a Pressure Pipe (it s not as crazy as it sounds) At first glance, it may seem a little strange to design a pressure pipe using the same tools used to design roads (especially since there is a whole set of tools just for pipes), but why does it sound strange? A road has horizontal curves to take you where you need to go and it follows the existing contours as closely as possible to reduce the amount of cut and fill needed. Isn t a pressure pipe essentially the same thing? Alignments are used for the horizontal placement of the pipe When designing a pressure pipe system, horizontal placement of the pipe often follows pretty simple guidelines, such as 5 feet off the edge of pavement or 10 feet inside the right-of-way. This greatly simplifies the horizontal drafting, because you will already have this information from either design documentation or existing topo surveys. At this point, you can simply offset the appropriate polyline to create your first approximation of the pressure pipe s horizontal layout. A few edits to the proposed layout will be necessary, such as joining lines at road intersections or zigzagging around obstacles, but the concept is simple. Once completed, an alignment can be created in just a few seconds by using the Create Alignment from Polyline command. Alternatively, one could also use the offset line as a guide and Create Alignment by Layout and use the Tangent-Tangent with Curves option. A 230 curve radius will allow for a 5 deflection for every 20 segment of pipe, but you might want to use a 500 radius curve just to be safe. Creating an alignment by layout does offer greater flexibility when making changes to the horizontal layout of the system, especially if the Tangent-Tangent with Curves method is used, but takes more time to create initially. The method of alignment creation really depends on what information is available to you at design time. Create an Existing Ground As with the alignments, Civil 3D users should already be familiar with the profile creation process, so we won t spend a lot of time on it. When creating the profile, go ahead and create a profile view at the same time. Although multiple profile view will be created, only a single view is needed for the design phase. Labels are not necessary, but a data band showing station and profile elevation comes in handy. 4

5 Draw the obstacles in your way, so that you can go around them We ve already gone around as many obstacles as possible when designing the horizontal layout of our system, but there are some things you just can t go around, such as: Water lines Other Utilities (phone, power, CATV) Sanitary Sewer Roads Storm Drains Streams and Rivers All of these you can simply go over or under (sanitary sewer always goes under water lines). It may require a directional bore to go under a road or stream, but you can still go under it. In order to design our line to clear the vertical obstacles, we need to locate them on our profile. Roads, streams and rivers should be pretty easy, as they should stand out on the existing surface profile. Just keep in mind that roads probably have a foot or more of subgrade you need to contend with and that your local environmental protection division might require more vertical clearance when crossing a water hazard. Sanitary sewer and storm drains can be drawn in using conventional pipes in Civil 3D (using both horizontal and vertical data) and will then show up on your profile in the correct location. Other utilities are the hard part. Water lines will most definitely be below the frost line, but it s anyone s guess as to how deep the cable TV line is. Once all the obstacles are located on the profile, we can now determine how deep the pipe needs to be. Parameters to consider when creating a Profile to represent the Pipe As stated earlier, pressure pipes are very similar to roads. If you re having problems with this concept, think of pressure pipes as roads for liquid stuff. Let s consider the design parameters for a pressure pipe and how these relate to a profile. The first parameter we ll look at is depth. A simple concept, right? Because it is a pressure pipe, grade really doesn t matter much. A pressure pipe is usually placed in the ground with at least 4 of cover (or below the frost line). Maximum depth is determined by how much you want to spend to dig the ditch. A depth of 6 is pretty easy to reach and only takes a few more scoops with the backhoe. 8 is the limit of most backhoes and small track hoes and anything deeper than that takes time to dig. 5

6 So, for all practical purposes, let s say that our depth range is 4-6 deep, with occasional short runs of 8 deep. Remember, the deeper the ditch, the more expensive it gets to dig it out. The other parameter to think of is vertical curvature. What s that? Pipes don t bend, so how can a line have a vertical curve? Most bell joints on PVC pipe allow for a 5 deflection, which looks like a curve from a distance. A little math indicates that this will result in a curve with roughly a 230 radius. When laying out the vertical curves, you might want to use a 250 minimum or maybe even 500 radius curve just to be safe. This will be set in the Curve and Spiral Settings on the Alignment Layout Tools toolbar and used when creating the layout. Drawing a Pressure Pipe profile Now for the fun part: creating the profile of the existing pressure pipe. From the Profiles pulldown menu, select Create Profile by Layout. Civil 3D will ask you to select the Profile View in which to create the profile. Select the Profile View you created earlier and complete the Create Profile dialog box. Name the profile, then select the profile style and profile label set. At this time, there is no need to have any labels, so select none. This keeps our drawing simple until we actually need the labels. 6

7 Click OK to bring up the Alignment Layout Tools and then select Curve Settings This is where you will set vertical curve parameters. Make sure that the curve type is set to Circular and set both the crest and sag curve radius to the desired value. In this case, both are set to a 250 radius curve, which is slightly above the calculated allowable radius using a 5 deflection for every 20 length of pipe. Press OK to continue. Once you have the vertical curve parameters set, the next step is to start actually drawing the profile. To begin this operation, simply select the Draw Tangents With Curves command from the Profile Layout Tools toolbar. 7

8 You will begin drawing the profile (which represents the pressure pipe being designed) at Station 0+00 on the profile view and the elevation will be near the existing ground elevation. There is no need to have an exact elevation just yet. This is Civil 3D, after all. In fact, when laying out the profile, you will draw it at or just slightly below existing ground elevation. Believe it or not, this is not in contradiction with our design criteria of 4 of cover. We ll just draw the pressure pipe at ground level (because it s much easier that way), then simply lower it to the proper depth when we re done. When placing the alignment, make sure you stay at or below the existing grade line at all times. If you do not stay below it, then your pipe will have less than the required amount of cover. Drawing exactly on top of the existing ground (reproducing it) is not what we are trying to accomplish. We want to just skim the low points in the immediate vicinity. In the example shown here, the profile is drawn through the three local low points, but it still follows the general slope of the existing ground. It helps to have a view of the profile that shows several hundred feet at a time. This will allow you to look ahead to determine where the next low or high spot will be. Since you are drawing the profile using the Tangents with Curves method, you are essentially picking the points of vertical intersection (PVI s) along this profile. After the initial laying out of the profile, curve radii can quickly be adjusted, which eliminates the need for many PVI s along the pipe. 8

9 Set the beginning and end elevations In order for our pressure pipe system to work, it needs to be connected to something on both ends (or at least the beginning), namely the pumping system. In the case of a water line, this may be a pump house or well head and a force main would most likely begin at a valve pit. In either case, the pump discharge pipe or flange will have a set elevation that we need to match. The same concept applied to the discharge end of the pressure system, whether it is another pipe, storage tank, treatment plant inlet or sanitary sewer manhole. To set these beginning and ending elvations, use the Profile Grid View, found near the right end of the Profile Layout Tools toolbar, which will bring up the Profile Grid. Double click in the PVI Elevation cell for the first item (the beginning of the line) and enter the correct elevation. Do the same thing for the last item (the end of the line). Match existing grade When you are finished with the initial layout of the profile along the entire length of the line, it s time to go back and match it up with the existing ground. Grip editing is the easiest. You can grab the PVI points to change the grade or elevation along the tangents and use the curve endpoint or midpoint grip to change the curve radius to match the top of a hill or bottom of a small valley. Just make sure that you do not make the radius less than what you started with. If you find that you need a small radius bend, simply remove the curve sub-entity. During construction, the contractor would need to use a fitting at the point where you removed the vertical curve. During this ground matching process, you may find it necessary to delete a PVI or add a new one. If you add one, make sure you also add in a vertical curve at that new PVI as well. 9

10 Check the profile for minimum radius on the vertical curves While still in the Profile Grid, scroll over to the right-hand side and check out the values in the Curve Radius column, making sure none of these are below the minimum vertical curve radius. Alternately, you could use the new criteria based design tools, along with design checks, to automatically flag those locations which have a too-small radius. Put the pipe in its place: 4 under Next, we will lower the pipe to its proper elevation. To do this, use the Raise/Lower PVIs button found in the middle of the Profile Layout Tools toolbar. The Raise/Lower PVI Elevation dialog box allows you to set the amount of elevation chance and whether to apply it to the entire line (as we will do) or apply it to only a certain range of the profile. Enter an Elevation change amount of -4, make sure that the All option is selected and then click the OK button. The entire profile we just designed will be lowered to its proper depth of 4 under the surface. We re getting close to being done with the design part of this process. The beginning and ending elevations of the profile have already been set correctly, as the line will be tied to a pump system on one end and a structure, pipe or some sort of discharge/distribution system on the other end. Also, A&V Valves will need to be located at the high points along our line and the entire line checked for correct design criteria. 10

11 Locate the High Points for placing A&V Valves Most governing agencies require the use of Air & Vacuum Release Valves (A&V valves). To do this the hard way, you would look at the entire profile and locate the points where the pipe grade changes from a positive to a negative slope. With Civil 3D, a simple and easy to create label style takes all the guess work out of this process. To place these labels, we simply use the Add/Edit Profile Labels, found under the pull-down menu for Profiles Add Profile View Labels. Do not mistakenly try to use the Add Profile View Labels, because it just won t work. After selecting the profile we want to label, the following dialog box is displayed. To locate the high points along our line, we want to select Crest Curves for the curve type, then select the High Points label style we created. Clicking on the Add>> button adds the crest curve high point labels to the set, then clicking OK puts the labels on the profile. A new feature in Civil 3D 2009 is the ability to place a profile high point label on the alignment as well, which will help you in the placement of A&V valve structures in plan view if so desired. 11

12 Place A&V Valve structures in Plan View Now that we know where these high points are in profile, it s time to place a structure in plan view to represent an A&V valve. While doing so, we might also find that some of our high points come out in the middle of a road or some other undesirable location, in which case we would need to modify the profile to account for this. Use of the new Profile Geometry Points labels in Civil 3D 2009 makes locating the high points in plan view quite simple. Once the high point has been located, place an A&V valve structure at the appropriate point. Using the insertion point of the high point label is the fastest way, but you could also place the structure by station/offset method (0 offset). Draw the A&V Structures in the Profile View After placing all the structures in plan view, we can draw and label them in profile view as well. From the Pipes pull-down menu, select the Draw Parts in Profile View. Civil 3D will then prompt for a part on the network to draw and which profile view to draw the parts in. The new A&V valve structures will appear in the profile view in the correct location, already labeled. At this time, the profile shows a single line representation of the pressure pipe. If you wish to show both the top and bottom of the pipe, just use the Copy Profile command, then lower the copy the corresponding diameter of the pressure pipe. 12

13 Putting it all on paper (Using the Plan Production Tools) After the design phase of our model has been completed, we need to produce a set of construction documents. Doing this without the assistance of Civil 3D is a time-consuming process, which could take a day or more to complete (depending on the length of the line). By using the Plan Production Tools within Civil 3D, we can reduce this time to about five minutes or even less depending on the layout of the system. Create the View Frames Plan Production Tools make use of View Frames to match up the Plan view and Profile view with predetermined viewports on your plan and profile sheet template drawing. Overlapping View Frames are created along the length of the alignment and multiple profile views are created to show the corresponding segment of the profile. To create the View Frames, select the Plan Production Tools from the General pulldown menu, then select the Create View Frames option. This will bring up the Create View Frames wizard, which will walk you through the process. 13

14 Select Alignment The only thing to do on this page of the Wizard is to select which alignment you wish to use and which part. Most likely, you will be using the Automatic setting, which will generate view frames along the entire length of the alignment. Sheets On this page of the wizard, you will choose the sheet type you want to generate, as well as the corresponding template file to use. Match Lines On this page, you will set where the match lines will be set. Although it depends on your drafting standards, setting the snap station value to 100 is a good safe bet. If you want to show an overlap between pages, then check the box (and set the value) for allowing additional distance for repositioning. 14

15 Profile Views Now you select which Profile View style to use, as well as the data band style. Create the sheets That s all there is to creating the View Frames. This is the time to review (and adjust) the view frames if necessary. Once the view frames have been created and satisfactorily adjusted, it s time to create the sheets. Without Civil 3D, this involves creating a new sheet with a viewport for the plan section and one for the profile section. Before any of the Plan Production tools are used, the template file must be set up correctly. The template file should contain both of the viewport mentioned, as well as a border. Additional items that could be in the template include notes, symbol legend or any other items that may be common to all sheets. To create the sheets, just select Create Sheets from the General Plan Production Tools pulldown menu. 15

16 View Frame Group and Layouts Here you will select the newly created View Frame Group and where you want the new sheet layouts created (one layout for each new drawing, all layouts in one new drawing or all layouts in the current drawing). You can also specify whether or not you want to place a North arrow on each of the sheets being created. Sheet Sets Choose whether to create a new sheet set or add the new sheets to an existing sheet set. 16

17 Profile Views The profile view and band styles are set at the time of view frame creation, but you can change some of the other settings, as well as selecting how the plan and profile views are aligned. Annotate the sheets When it comes to annotating the sheets, it s back to the basics. You can use the relatively new multileaders to call out the pipe size and material, annotative blocks for erosion control symbols and annotative mtext object for notes, but it s still a manual process. Wrap-Up Civil 3D, while providing precise rule-based pipe design, has no tools intended for pressure pipe layout or design. However, the creative application of tools intended for road design will result in a set of construction documents with a minimal amount of effort. While it is true that the method discussed in this course does not offer the same level of precision as that offered by using Civil 3D pipes and null structures, it is also true that that level of precision is not needed on a pressure pipe system. Pressure pipe design criteria are much more relaxed, often consisting of little more than a minimum depth. If you are still uncertain of this alternative method, then you should also consider the source of your topo data for this type of project. Sometimes this data consists of little more than an aerial survey, in which case the vertical precision is plus-or-minus 10. Even if a ground survey is run, the survey 17

18 won t pick up every little variation in elevation along the proposed route. In fact, the proposed route probably will not be determined until after the survey is completed. After taking all this into consideration, the conclusion can be drawn that a pressure pipe system really is little more than a pretty picture. Why not take advantage of the roadway tools provided in Civil 3D to draw this picture as quickly and painlessly as possible. 18