A Field Test Study on Instrumented Soil Nail Installed in Cut Slope

Soil nailing is a technique routinely used in Hong Kong whereby closely spaced steel bars are installed into a slope so that its stability conditions can be improved. A full-scale field test has been carried out by The Department of Civil Engineering of The University of Hong Kong to study the development of passive load along the full length of soil nails when subjected to induced rise in groundwater table. The cut slope was formed to a very steep angle of 55° and 10 m high in completely decomposed volcanic material. Grouted curtain was also formed behind, at the bottom and on both ends of the slope in order to form an impermeable barrier that would allow groundwater table to increase artificially by injecting water into slotted PVC pipes. Nine number of soil nails (in regular 2 m c/c spacing of 3 rows and 3 columns) of 6 m long high yield steel bar were installed at 15° from horizontal into the formed cut slope. Instrumentation included strain gauges along the nails, inclinometers, piezometers, and settlement prisms. This paper describes the method of construction and the load developed along the soil nails when the groundwater table was raised to the ground surface. It was found that the measured passive load along the soil nail was smaller than the commonly assumed design parameters, an indication that substantial savings can be achieved if mobilization of shearing resistance along the full length of the soil nail was considered in routine design. Finite element analysis has also been carried out to compare the measured load with the simulated load and the stability factor is compared with the factor of safety at each stage of loading

Stabilization of a 30 m High Riverbank in Canada with Nails, Plates and Roots

The natural river processes along a 30 m high riverbank of one of the largest tributaries to Lake Superior cause periodic landslides. After arresting toe erosion, local authorities needed to protect the infrastructure at the crest from further damage as the slope continued to flatten towards its long-term angle of repose. A long-term hazard management strategy was applied using the cautionary zone approach (CZA). Design criteria included a target safety factor, no construction impacts, no maintenance and a 75-year design life. The solution drew from 3 technologies: soil nails, laterally loaded piles and biotechnical stabilization. Steel nails, 35 mm diameter, were designed in bending perpendicular to slip surfaces and installed on a 1 to 1.5 m grid. Lightweight equipment working on the slope installed the 4 to 12 m long nails very rapidly without drilling or grouting. For shallow flow slides around a rigid nail, plate heads were added. A facing of roots controlled soil movements between nails and provided a natural look with the system completely out of sight. Three years of performance monitoring data are presented, and confirm a successful case history. This paper describes an innovative approach used to stabilize a landslide prone area in an urban environment

Times-History Finite Element Dynamic Analysis - Soil Nail Wall - San Manuel Casino - Highland, California

The site of the proposed Phase II Parking Facility at the San Manuel Resort Casino, Highland, California, is on a sloped terrain where there is a 35 ft. grade differential from the north to the south end of the planned structure. PB&A, Inc. was selected to design a 12,000 square foot Soil-Nailed wall with a maximum height of 37 ft. to protect the Parking Structure from the soil pressures resulting from sloping ground conditions at the site. The project site is located within 100 feet of the San Andreas Fault in the highly seismic Southern California region, characterized by numerous active faults and high level seismic activity. The alignment of the Soil-Nailed wall is located at the edge of the Alquist-Priolo Earthquake Fault Zone. The proximity of the Soil Nail Wall to this major seismic fault necessitated the preparation of a dynamic analysis to better assess the behavior of the wall during a seismic event. The main objective of this analysis was to determine the maximum deformation the Soil-Nailed Wall would undergo during an earthquake so that an adequate separation could be defined between the structure of the parking garage and the Soil-Nailed Wall. In addition, vertical soil nails (V-Nails) were to be installed directly behind the shotcrete facing of the wall to provide localized surface stability during construction. The effect of the V-Nails was to be studied in relationship to the overall performance of the wall. The Geotechnical Engineer of Record, Kleinfelder, provided three sets of spectra-matched outcropping acceleration time histories from three representative earthquakes: Duzce earthquake, Turkey (11/12/1999), Landers earthquake, United States (06/28/1992) and Chi-Chi earthquake, Taiwan China (09/20/1999). Using the information gleaned from these time histories, PB&A constructed a half-space model in PLAXIS, a Finite Element software application widely used in the industry. To construct the model, engineers used the Mohr-Columb soil model applied to layers of soil at the project site. The soil strength and stiffness parameters were based on the recommended values outlined in the Geotechnical Report and the shotcrete wall and soil nails were modeled with the plate (Beam) and ground anchor element, respectively. It was necessary to transform the acceleration time histories to the proper depth at the bottom of the PLAXIS model, as the acceleration time histories were recorded as the outcropping motions,. To accomplish this, the deconvolution process was performed in the SHAKE91 program. In the staged construction calculation, the horizontal and vertical displacement, velocity and acceleration are recorded at the top and the bottom of the wall in each step

COMPILATION OF DESIGN METHODOLOGY FOR SOIL NAILING

Soil nailing is an in-situ technique for reinforcing, stabilizing and retaining excavation and slope. The basic concept of soil nailing is reinforces the existing ground by inserting a passive inclusion into the soil in a closely spaced pattern to increase the overall shear strength of the in-situ soil and restraint its displacement. The nails used in soil-nailing retaining structures are generally steel bars or other metallic elements that can resist tensile, shear stresses and bending moment

The Simplified KZP5 Method for Soil Nail Design in Granular Soils

A lot of soil nail retaining walls in southern California are under construction. Some of them will be used as shoring systems for bridge or other kind of retaining wall constructions. Design and design review process are very time consuming, and the possibility of mistakes encourages us to find a simplified method for designing the soil nail walls. The maximum height of the soil nail walls in that region were about 14m, including 9 rows of 25mm steel rods (nails) in 150mm diameter holes with different lengths. Whole length of the drilled holes will be filled with grout after setting the nails in. A steel mesh along with the rebar will be set at middle of the shotcrete thickness before placing shotcrete. After placing shotcrete, the bearing plate and the nut will be set at each nail location. At this stage, the shotcrete and the nails would be enough to act like as shoring system. To build a soil nail retaining wall another mesh of rebar will be installed between the shotcrete and the LOL (lay out line) of the wall before placing the wall concrete The simplified KZP5 method is based on the soil mechanic concepts for the granular soils and the Boussinesq strip load method for the possible surcharge behind the wall. In this paper besides considering the soil nail wall design and construction procedure, regular dimensions and loading, the simplified method (KZP5) will be presented. An example will be solved based on this and the conventional method to show the accuracy of the simplified method. An example will be considered to show the accuracy of this trail and error method

Þinghald að fornu : fornleifarannsóknir 2003

No abstract available

Test Excavations at the Spanish Governor\u27s Palace, San Antonio, Texas

Test excavations were carried out in October 1996 by the Center for Archaeological Research of The University of Texas at San Antonio in front of the Spanish Governor\u27s Palace in Military Plaza in downtown San Antonio. Planned for the retrieval of information on the depth and present condition of the foundations of the building, the excavations also recovered important information on previous occupation of the site and construction methods used when the palace was built

Structure Analysis of Net Systems from Flexible Nails in Soil Reinforcement

Import 26/02/2015Práce provádí analýzu činnosti síťové soustavy z netuhých zemních hřebíků, která má, podobně jako kořenová soustava vegetačního pokryvu, vyztužovat - stabilizovat zeminy. Jednotlivé kapitoly práce se zabývají: podmínkami vytvoření síťové soustavy; variantami uspořádání síťových soustav s ohledem na vyztužování zemin; statickou činností jednoho hřebíku, síťové soustavy a skupiny uspořádaných síťových soustav; praktickým aplikačním možnostem skupiny uspořádaných síťových soustav při vyztužování – stabilizaci zemního prostředí. Poslední kapitola práce uvádí silovou metodu řešení návrhu parametrů skupiny uspořádaných síťových soustav a jednoduchý příklad její aplikace při vyztužení – stabilizaci svahu zářezu v zemině.The thesis analyses the ability of the net arrangement of flexible soil nails, that like the root system of the vegetation, reinforced - bind the soil in place. Particular chapters deal with: conditions for a net arrangement constitution; design variants of the net arrangement having regard to the reinforcement of soil; static work of a single nail, static work of net arrangement of nails and last combined static work of several nets; practical application of combined nets to reinforce soil - to bind the soil ground in place generally. The last chapter displays a balance force method to design the parameters of the soil nail nets and a simple example of its application for the soil reinforcement of slope cut in the soil ground.224 - Katedra geotechniky a podzemního stavitelstvívýborn