Design Flexibility - The SRW System is composed of units whose size and weight makes it possible to construct walls in the most difficult of locations. curves and other unique layouts can be easily accommodated. Segmental retaining walls have the ability to function equally well in large-scale applications (highway walls, bridge abutments, erosion control, parking area supports, etc.) as well as smaller residential landscape projects.
Performance - Unlike rigid retraining wall structures, which may display cracks when subjected to movement, the flexible nature of segmental retaining walls allows the units to move and adjust relative to one another without visible signs of distress.
Site Design Consideration - Typical designs and specifications for segmental retaining walls should be prepared by a designer who has technical knowledge of soil and structural mechanics. Each SRW unit manufacturer can provide design information tailored to that product, which will indicate the wall heights and design conditions when an SRW should be designed by a qualified engineer. In addition, SRW systems should be designed by a qualified engineer when:
Geosynthetic Length and Spacing - For soil-reinforced segmental retaining walls, geosynthetic reinforcement increases the mass of the composite SRW structure, and therefore controlled by external stability calculations. Increasing the length of the geosynthetic layers increases the SRW's resistance to overturning, base sliding, and bearing failures. In some instances, the length of the uppermost layer(s) is locally extended in order to provide adequate anchorage (pullout capacity) for the geosynthetic layers. The strength of the geosynthetic and the frictional interaction with the surrounding soil may also affect geosynthetic length.
A sufficient number and strength of geosynthetic layers must be used to satisfy horizontal equilibrium with soil forces behind the wall and to maintain internal stability. In addition, the tension forces in the geosynthetic layers must be less than the design strength of the geosynthetic and within the allowable connection strength between the geosynthetic and the SRW unit.
Drainage System - Drainage is an essential part of a properly designed SRW. Drainage materials are generally well-graded aggregates. A properly designed drainage system relieves hydrestatic pressure in the soil, prevents retained soils from washing through the face of the wall, provides a stiff leveling pad to support a column of stacked facing units, and provides a working surface during construction. Surface water drainage should be designed to minimize erosion of the topsoil in front of the walltoe and to direct surface water away from the structure.
Batter - Segmental retaining walls are generally installed with a small horizontal setback between units, creating a wall batter into the retained soil. The wall batter compensitates for any slight lateral movement of the SRW face due to earth pressure, ensuring that the finished wall does not appear to rotate.
Unit Size and Shear - In conventional (gravity) SRWs, where the stability of the system depends primarily on the mass and shear capacity of the SRW units, increasing the SRW unit width or weight provides greater stability, larger frictional resistance, and larger resisting moments. in soil-reinforced SRWs, heavier and wider units may permit a greater vertical spacing between layers of geosynthetic.
All SRW units provide a means of transferring lateral forces from one course to the next. Shear capacity provides lateral stability for this mortarless wall system. This is accomplished by shear keys, leading lips, trailing lips, clips, pins, or compacted columns of aggrigate in open cores.
Embedment - The primary benefit of wall embedment is to ensure the SRW is not undermined by erosion of the soil in front of the wall. Increasing the depth of embedment also provides greater stabiliyt when site conditions include weak bearing capacity of underlying soils, steep slopes near the toe of the wall, potential scour at the toe (particularly in waterfront or submerged applications), seasonal soil volumn changes, or seismic loads.
Elements - The basic elements of each segmental retaining wall system are the foundation soil, leveling pads, segmental retaining wall units, retained soil, drainage fill, and, for soil-reinforced SRWs, the soil reinforcement.
Construction - The success of any segmental retaining wall installation depends on complete and accurate field information, careful planning and scheduling, the use of specified materials, proper construction procedures and inspection.
It is good practice to have the retaining wall location verified by the owner's representative. Existing and proposed finish grades shown on the drawings should be verified to ensure the planned design heights are in agreement with the topographic information from the project grading plan.
The contractor should coordinate the delivery and storage of materials at the site to ensure unobstructed access to the work area and availability of materials. materials delivered to the site should be accompanied by the manufacturer's certification that the materials meet or exceed the specified minimum requirements.
Construction occurs in the following sequence:
As with any structure used to retain soil, careful attention should be paid to the compaction equipment and procedures used during construction. When compacting soil within 3 ft. (0.9 m) of the face of a wall, compaction tools should be limited to hand operated equipment, preferably a vibrating plate compactor. Reinforced soil can be compacted with walk-behind or self-propelled riding compaction equipment.
Decorative Wall Systems - Where form meets function.. A retaining wall should serve a dual purpose of pleasing the eye and blending the levels of earth into your outdoor living space. Ideal Wall Systems makes this project easier by offering a product that is superior to other interlocking wall systems. towne Tree & Landscaping, Inc. carefully chooses stones, pavers, and other elements to enhance your landscape area.
This retaining wall was installed to create a safe and attrative play area. This multifunctional wall is a decorative addition to the play area and also serves to hold in place the play mulch.
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