Presentation on theme: "CONSTRUCTION OF SOIL NAILING WALLS"— Presentation transcript:
1 CONSTRUCTION OF SOIL NAILING WALLS Presented by:Student’s Name
2 Contents Subsoil considerations Design consideration Construction considerationsConstruction and installation stepsAdvantagesDisadvantages
3 Subsoil Considerations Favorable ConditionsSoil should be stiff or hard with fine grainsGrains should have low plasticitySoil should have natural cohesion provided by either capillary water of natural cementationSubsoil with weathered rock should be uniformly weathered
4 Subsoil Considerations Unfavorable ConditionsDry and poorly grained soilsSoils lacking natural cohesion or cementationSoil with a lot of ground waterSoil with a lot of cobbles and bouldersSoil that is not uniformly weatheredHighly corrosive soils
5 Design Considerations Drainage considerationsUse of geo-composite drain strips along the excavation walls to allow water to be discharged through weep holes at the bottom of the wallUse of drain pipes to control ground water pressure.Designing ditches behind the walls to prevent surface water from infiltrating behind the walls
6 Design Considerations Other considerationsThey should be designed to resist damage caused by frost action by increasing thickness of soil wall be using porous materialThe wall should be designed in a way that it can withstand both external loads such as highways and the weight of the temporary facing.
7 Construction Considerations The state of the construction material should be in good physical conditions and as per the design specificationCheck to ensure the excavation walls are stable and that the nails are properly installed with the right length size and spacingCheck to ensure the completed soil wall is not tampered with during excavation of the next phase
8 Construction Considerations The contractor should ensure that the soil nail drilling is done as per the specificationsThe amount of time the drill holes remain open to avoid cavingMaterials are properly handled to avoid damagesEnsure nails are properly grouted in the grouted column with no gaps left
9 Construction and Installation Steps Excavation is done to a level the walls can support themselves for 2 days. It is made about 6feet and wide enough for equipmentDrilling the nail holes according to the design specificationsInstalling the nails using centralizers together with pipes filled with grouting cement. Geo-composite walls are also installed in this phase.
10 Construction and Installation Steps 4. Construct temporary facing to support the open cut soil using a reinforced layer of welded wire mesh between the facing thicknessConstruction of subsequent levels by repeating steps 1- 4Finally construct a permanent facing using reinforced concrete and fabricated panels
11 Advantages of Soil Nail Walls Construction advantagesDoesn’t disrupt the flow of traffic as compared to other methodsIt provides a less congested excavation bottomIt has a rapid construction scheduleThe design can be easily adjusted without creating safety issues
12 Advantages of Soil Nail Walls PerformanceResultant wall are very flexibleThe structures have very small deflectionsThe walls can withstand seismic activitiesCostOverall cost is lower than other methodsUses cheaper materials such as shortcrete
13 Disadvantages of Soil Nail Walls Can be implemented by highly trained and experienced contactors only.It is not favorable in areas with a lot of ground waterThe presence of different utilities pose a challenge in terms of inclination and length of the soil nails during construction in the upper rows