بسم الله الرحمن الرحيم Soil Nailing for slope stability 4/28/2017 King Fahd University of Petroleum & Minerals Civil Engineering Department Term (101), CE553 Soil and site improvement Soil Nailing for slope stability Instructor : Dr. Talat Bader Presented by: Salem Babtain ID No. 200804180 CE 553 CE 553 Friday, April 28, 2017

Outline Introduction Literature review Slope Failure Soil Nailing 4/28/2017 Outline Introduction Literature review Slope Failure Soil Nailing Case Studies Conclusion CE 553 Friday, April 28, 2017

Soil nailing is used mainly to protect soil slope failure 4/28/2017 Introduction Soil nailing is a technique in which soil slopes, excavations or retaining walls are reinforced by the insertion of relatively slender elements - normally steel reinforcing bars. Soil nailing is used mainly to protect soil slope failure CE 553 Friday, April 28, 2017

Literature Review 1960's and earlier in 1961 in the 1970's in 1972 4/28/2017 Literature Review "New Austrian Tunneling Method" (NATM), in which grouted rock bolts and shotcrete were used for supporting tunnels 1960's and earlier in 1961 permanent support of retaining walls in a cut in soft rock in France. The use of grouted "soil nails" and driven soil nails, which consist of solid steel bars and steel angle iron, continued to grow in the 1970's, in France, Germany and north America in the 1970's The first wall built in France using current soil nail techniques was reported to have been built by Soletanche, in Versailles in 1972 CE 553 Friday, April 28, 2017

Guidelines and Manuals 4/28/2017 Guidelines and Manuals One of the first national guideline publications for soil nailing. ( In Japan) In 1987 in France (Clouterre Program) $ 5 million study to develop design methodology for soil nail walls "Recommendations of Clouterre," published in 1991 In the 1991 Federal Highway Administration published its "Manual for Design and Construction of Soil Nail Walls.“ In 1993 (FHA) CE 553 Friday, April 28, 2017

Slope Failure What is slope failure ? 4/28/2017 Slope Failure What is slope failure ? -The slope can not support itself - Gravitational and seepage forces cause disturbing force - Soil friction provide resisting force - If disturbing moment > resisting moment Slope will failure CE 553 Friday, April 28, 2017

4/28/2017 Type of slope failure CE 553 Friday, April 28, 2017

4/28/2017 Type of landslide CE 553 Friday, April 28, 2017

Slope Failure Major landslide in past history 18 person killed 4/28/2017 Slope Failure Major landslide in past history 18 person killed 67 person killed CE 553 Friday, April 28, 2017

Factors affecting slope failure 4/28/2017 Factors affecting slope failure Major landslide in past history Geometrical changes Shocks & vibrations Change in water regime Removal of vegetation Weathering 18 person killed 67 person killed CE 553 Friday, April 28, 2017

Slope stabilization methods 4/28/2017 Slope stabilization methods Natural Masonry Soil Nailing Others Shotcrete CE 553 Friday, April 28, 2017

Soil nailing method Main function of soil nailing is: 4/28/2017 Soil nailing method Main function of soil nailing is: Provide a resisting force against slope failure CE 553 Friday, April 28, 2017

Soil uses Soil nailing is used to reinforce -tunnels wall support 4/28/2017 Soil uses Soil nailing is used to reinforce -tunnels wall support -soil cut slopes -retaining wall support -excavations, -disturbed terrain and -natural hillsides stabilize CE 553 Friday, April 28, 2017

Principle of Soil nailing 4/28/2017 Principle of Soil nailing Active Zone Slip Surface Passive Zone - In slope stability calculations, the result needs to obviously ensure that the resisting forces are greater than the force tending to cause slope failure. CE 553 Friday, April 28, 2017

There are three types of FOS 4/28/2017 Factor of Safety ( FOS ) - FOS is defined as the ratio of total resisting forces to total disturbing forces or total overturning moment. 1- There are three types of FOS 2- 3- CE 553 Friday, April 28, 2017

4/28/2017 Nails Generally small-diameter nails (15-46 mm) Driven nails are the quickest and most economical to install. Driven Nail Steel bars, with diameters ranging from 15 to 46 mm, stronger than driven nails Grouted nails are inserted into boreholes of 10-15 cm and then cement-grouted. Grouted Nail CE 553 Friday, April 28, 2017

4/28/2017 Nails Launched nails Nails are fired directly into the soil with a compressed-air launcher. Used primarily for slope stabilization, this technique involves the least site disturbance. Jet-grouted nails A composite of grouted soil and a central steel rod, up to 40 cm thick. Nails are installed using a high-frequency vibropercussion hammer, and cement grouting is injected during installation. CE 553 Friday, April 28, 2017

Equipments used Drilling Equipments CE 553 4/28/2017 Friday, April 28, 2017

Equipments used Grout Mixing Equipment mortar grouting pump CE 553 4/28/2017 Equipments used Grout Mixing Equipment mortar grouting pump CE 553 Friday, April 28, 2017

Equipments used Shotcreting Equipment The compressor shall have 4/28/2017 Equipments used Shotcreting Equipment The compressor shall have Very high rate capacity. CE 553 Friday, April 28, 2017

Components of soil nail 4/28/2017 Components of soil nail Nails Centralizer Grout Head CE 553 Friday, April 28, 2017

Construction Sequence 4/28/2017 Construction Sequence 1-Initial Excavation 2-Drilling of holes 3-Insertion of nail 4-Grouting 5-Head construction 6-Shotcrete CE 553 Friday, April 28, 2017

Construction Sequence 4/28/2017 Construction Sequence CE 553 Friday, April 28, 2017

Advantages Economic Construction redundancy 4/28/2017 Advantages Economic Relatively Low Cost. According to Cornforth (2005) mentioned that, soil nailing can result in a cost saving of 10 to 30 percent when compared to tieback walls. Construction techniques are simple and quick. So, rate of construction fast. Construction redundancy If any one of soil nails becomes overstressed, it will not cause failure of the slope. It will redistribute the overstress to the adjoining nails system Ortigao (2004). CE 553 Friday, April 28, 2017

Advantages Adaptability Flexibility 4/28/2017 Advantages Soil nails can be used in heterogeneous ground. Soil nailing generally is more feasible than other techniques. This is because it involves only small-diameter drilling for the installation of the inclusions Adaptability Flexibility Soil nailing retaining structures is more flexible than other slope sterilization technique. It can be integrated with other earth retaining system such as Tie-back wall and retaining wall. CE 553 Friday, April 28, 2017

Advantages Adaptability Flexibility 4/28/2017 Advantages Soil nails can be used in heterogeneous ground. Soil nailing generally is more feasible than other techniques. This is because it involves only small-diameter drilling for the installation of the inclusions Adaptability Flexibility Soil nailing retaining structures is more flexible than other slope sterilization technique. It can be integrated with other earth retaining system such as Tie-back wall and retaining wall. CE 553 Friday, April 28, 2017

Limitations Unsuitable soil Groundwater 4/28/2017 Limitations Unsuitable soil Cohesionless soil slopes are not suitable for soil nails slope stability. This is because during the drilling of the hole or un-grouted hole may collapse Groundwater Soil nailing is not suitable above groundwater level. a drilled hole cannot support itself due to water saturation and the hole will collapse. Furthermore, water cement ratio in grouting will effect. CE 553 Friday, April 28, 2017

Limitations Vibration sensitive prolong downpours Utilities 4/28/2017 Limitations Vibration sensitive drilling may affect the adjacent structures. Some building structures are vibration sensitive such as Historical Buildings. prolong downpours Slope failures can be seen Sometimes especially during raining seasons or after heavy prolong downpours. Ground becomes fully saturation, in this case soil nailing combined with retaining wall is better. Utilities sometimes utilities such as buried water pipes, underground cables and drainage systems cause a problem facing soil nails inside the slope. CE 553 Friday, April 28, 2017

Soil nailing failure Pullout failure 4/28/2017 Soil nailing failure Pullout failure Result of insufficient embedded length into the resistant zone Resistant zone CE 553 Friday, April 28, 2017

Soil nailing failure Nail tendon failure 4/28/2017 Soil nailing failure Nail tendon failure Results from inadequate tensile strength of the nails to provide the resistant force to stabilize the slope CE 553 Friday, April 28, 2017

Soil nailing failure Face failure 4/28/2017 Soil nailing failure Face failure Results if relatively small and nominal shotcrete thickness and reinforcement is adequate. CE 553 Friday, April 28, 2017

Site Investigation Site Investigation -Desk study -Site Reconnaissance 4/28/2017 Site Investigation Site Investigation -Desk study -Site Reconnaissance -Collection of field data including Investigation and laboratory testing. -Follow-up investigation and design review during construction CE 553 Friday, April 28, 2017

-Collapse of drilled-hole 4/28/2017 Major impacts The major impacts to soil nailing works -Loss of grout though the fractured rock mass, open joints and cavities -Collapse of drilled-hole -Poor nail-to-soil interface resistance due to disturbance of drilled-hole CE 553 Friday, April 28, 2017

4/28/2017 Case Study (1) Cowboy Stadium CE 553 Friday, April 28, 2017

Case Study (1) DYWIDAG Company -Cowboy stadium construction CE 553 4/28/2017 Case Study (1) Vertical Slope 18 m below the ground They used: - 8200 nails About 670 tone 16m to 18m bars long DYWIDAG Company -Cowboy stadium construction CE 553 Friday, April 28, 2017

Case Study (1) Advantage of soil nailing wall Fast work 4/28/2017 Case Study (1) Advantage of soil nailing wall Fast work flexibility of soil nail construction with progress of excavation. cost relatively cheaper than other method. CE 553 Friday, April 28, 2017

Case Study (2) Slope failure 4/28/2017 Case Study (2) Slope failure Slope failures not only will cause economic loss to the public but also may result in loss of life Malaysia, 1999 CE 553 Friday, April 28, 2017

Just view days after soil nails constructed, slope failed 4/28/2017 Case Study (2) Cause of failure -Prolong rain fall -Design mistakes -failure was behind the soil nails Just view days after soil nails constructed, slope failed CE 553 Friday, April 28, 2017

Remedial Implementation 4/28/2017 Case Study (2) Remedial Implementation In this case the proper solution was: Build a retaining wall combined with soil nailing. Gentle slope behind the retaining wall Drainage system should be used Reinforced soil nails wall was selected in this case after comparison of construction cost and time with other types of retaining walls CE 553 Friday, April 28, 2017

4/28/2017 Case Study (2) 3 years after the completion of the remedial works CE 553 Friday, April 28, 2017

4/28/2017 Conclusion Soil nail construction has been shown to be a simple technology and does not need complex machines. This method can provide a lower construction, period, and can provide good stabilize for slope failure. Soil nailing has some advantages and some limitation. So, proper investigation and design should be taken. soil nailing should be avoided in some cases CE 553 Friday, April 28, 2017

Thank you Q & A CE 553