Civil Engineering Chapter 22 Homework The Follow The Rough Trench Excavate Level

Document Type
Homework Help
Book Title
Landscape Construction 3rd Edition
Authors
David Sauter
CAUTION
92
Exercise 22
Wall Base Preparation
and Wall First Course
Installation/Stepping
First Course
OBJECTIVE
The objectives of this exercise are to install base material
and properly install the first course of a landscape retain-
ing wall using ties/timbers, segmental concrete wall units
Follow manufacturer’s instructions when using
equipment. Use caution when cutting and
installing wall materials. Obtain assistance when
lifting wall materials.
TEXTBOOK REFERENCE
Information related to this activity can be found in the
INTRODUCTION
The longevity of a landscape retaining wall depends on
several factors, including the quality of the base upon
which the wall rests. Proper preparation of the site and
Base Installation
To prepare a granular base for a landscape retaining wall,
use the following steps:
Lay out the wall alignment and grades.
Excavate sod from 2 feet in front of to 2 feet
behind the wall for the entire wall alignment
(Figure 22–1).
97171_22_ch22_p092-097.indd 92 14/06/10 8:58 PM
Exercise 22 Wall Base Preparation and Wall First Course Installation/Stepping First Course 93
is placed below finish grade. The trench should
follow the elevation of the alignment. Excavate
stepped portions of the wall separately. When
excavating, any loose or unstable materials
encountered should be removed and replaced
with granular backfill.
3/4 inch to 1 inch crushed stone.
Level the base material end to end and front to
back for each level of the wall.
Compact using a vibratory plate compactor.
The addition of a 1/2 inch to 1 inch layer of finer
granular material will accommodate the leveling
of the first course of wall material when placed in
the trench. Crushed stone that passes a 3/8inch
sieve is suitable for this purpose. Relevel and
recompact after granular material is added.
changes. Failure to properly level a wall will create prob-
lems that multiply as wall height increases. Stepping
the first course up a hillside can also create potential
problems if the level and alignment are not maintained
through the steps. When walls encounter embankments,
this stepping may occur rapidly. Walls should never step
Place a tie/timber on the base material, ensuring
the tie/timber’s front is properly aligned. If the
project requires the top of the wall stop at a
particular elevation, use a survey instrument to
verify elevations (Figure 22–2).
Using a carpenter’s level, check for level end to
end. If tie/timber is not level, add or remove base
material under the tie/timber as necessary.
Using a carpenter’s level, check for level front to
back or for the proper leaning batter. If the level is
not correct, tip the tie/timber forward or backward
and remove or add base material as necessary.
Wall material
(any material selected)
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94 Exercise 22 Wall Base Preparation and Wall First Course Installation/Stepping First Course
Stepping First Course
In instances where the wall steps up, complete the
lower course of wall to the point where the step
occurs.
Segmental Unit and Stone Walls
Perform the following checks before placing the first
course for segmental units:
pins and the bottom should have openings to
receive pins. For lipped units the bottom will
have a thickened lip. This lip should be knocked
off with a hammer for all blocks used on the base
base to speed the leveling process.
Place the first unit or stone, ensuring the front of
the block is properly aligned (Figure 22–3).
Check for level side to side. If the block is not
level, adjustments may be made by scratching
away base material or adding base material under
Front of wall
A. Position with proper
alignment
B. Check for level end to end
(add or remove base material)
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Exercise 22 Wall Base Preparation and Wall First Course Installation/Stepping First Course 95
Stepping First Course
If the wall is to step up only one course or slowly,
create a base for the upper course using the
instructions provided earlier in this exercise. The
base material for the upper course should be level
with the top of the blocks in the lower course and
Figure 22–3 Installing segmental unit or stone first course.
Front
of wall
A. Position with proper
alignment
B. Check level side to side,
adjust if necessary
E. Recheck level side to side
and front to back before
placing next unit
F. Set next unit. Use palm of hand
to verify and unit is flush with first
unit. Repeat steps A–E for
second unit. Use long level over several
units to check side to side level
2nd unit
1st unit
© Delmar/Cengage Learning.
Cross-Section
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96 Exercise 22 Wall Base Preparation and Wall First Course Installation/Stepping First Course
PREREQUISITE EXERCISES
Students should have successfully completed Exercise 5,
Tool Operation and Construction Techniques, Exercise 6,
Cutting of Paving and Wall Materials, Exercise 8, Construc-
tion Staking, and Exercise 9, Grade Staking, before begin-
ning this exercise.
EXERCISE 22 PART A
MATERIALS REQUIRED
• Square-nosed shovel
Mason’s level (48 inch preferred)
• Garden rake/screed
Granular base material, 3/4 inch to 1 inch
Granular base material, 3/8 inch
EXERCISE DESCRIPTION
To complete this exercise prepare a 20 foot long base for
a landscape retaining wall (Figure 22–5). This base can be
on a level surface that cuts across the run of a slope or can
parallel the run of a slope, gradually stepping up it.
20'
Flat Slope
Note: This exercise practices installation of a base with
relative grades. When construction plans detail a specific
grading scheme, a survey level must be used to establish
the precise elevation of the base.
EXERCISE 22 PART B
MATERIALS REQUIRED
Proper clothing and safety gear
Mason’s level (48 inch)
Torpedo level (6 inch)
Vibratory plate compactor (prepared for
operation)
Hydraulic block splitter or cutoff saw, or wet
Granular base material
EXERCISE DESCRIPTION
To complete this exercise construct a 20 foot long base
segment of landscape retaining wall two courses high
using both ties/timbers and segmental units or stone
(Figure 22–6). This wall should include a 10 foot long level
section and a 10 foot long section that steps up a gradual
slope. Complete the base as directed in Exercise 22 Part A.
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Exercise 22 Wall Base Preparation and Wall First Course Installation/Stepping First Course 97
Note: This exercise practices installation of a wall with
relative grades. When construction plans require specific
Operate power equipment under supervision.
Serious injury or death could result
97171_22_ch22_p092-097.indd 97 14/06/10 8:59 PM

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