Earth Anchors For Retaining Walls

Tieback walls are comparatively much simpler to design than the other types of retaining walls. The whole point of a retaining wall is to keep earth held back. Today, Ancor Loc New Zealand work in this field with an outstanding reputation of product quality and customer service. The anchor tendon is then loaded or tensioned to a pre-determined load and then secured against piles, whalers (steel or concrete), steel plates, concrete or timbers. Bowing or leaning foundation walls are one of the most common signs of a shifting or settling foundation. The main purpose of geotechnical ground anchors is to prevent horizontal movement, while stabilising retaining structures, including sheet pile, bored concrete pile and steel tubular walls. • Retaining walls • Roadways • Land development • Levees / Dams • Revetments • Slope failures • Parking lots LOAd-bEARINg SupERIORITY Of SCREW ANCHORS Bearing plates are spaced along the entire length of screw anchors. Helical tieback anchors provide additional lateral support for soldier piling and lagging as well as driven steel sheet temporary retaining walls. There are quite a few options for that, but now I am looking at doig an approximately 300' curved retaining wall with a max height of about 12'. Different types of retaining walls are used to retain soil in different places. Whether you need a residential retaining wall for functional purposes or you want to bring a new element into your yard’s design, we’ll help you create the perfect stone wall. The cost of a retaining wall depends on the material chosen, the overall height of the wall and the length of the wall. deep cable rods or wires are driven deep sideways into the earth, then the ends are filled with concrete to provide anchor. d or defl ect less. Lagging walls are among the least expensive retention systems. Then, the boxes are filled with crushed stone or other coarse granular materials to create a free draining structure. Read expert tips on how to repair a retaining wall—a landscaping wall that can be used to retain earth after an excavation. The Contech ANCHOR WALL system is the first all-steel approach to construction of shoreline walls.



Penetrator ground screw, arrowhead cabled, bullet guying anchors. A weep hole filter relieves water pressure and prevents retaining wall failure. Plus, if there is any groundwater that is behind the retaining wall, that adds a tremendous amount of hydrostatic pressure. Helical tiebacks are horizontal rods used to support to strengthen and straighten bowed basement or retaining walls. The Prime Retaining Walls is a specialty firm and one of the leaders in making retaining walls Dallas. create an intelligent aid for solving retaining wall problems. These anchors help walls resist pressures that force them forward or cause them to pivot on footing material. We're going to talk about the fundamentals of building a boulder retaining wall and why these simple principles are usually ignored. If the structure of your building or home is bowing or cracking, we offer a variety of wall repair options to stabilize your foundation. We made a retaining wall/shelf below the rapidobe wall. addresses the earth pressures acting on the abutments as well as retaining walls and reinforced slopes. After installation, wall anchors can often be tightened over time to further straighten your foundation walls and pull them back to their original position. Reinforced Soil Retaining Walls-Design and Construction Prof. Bridge Retaining Wall: A retaining wall that meets all of the following conditions: 1. Retaining walls can be constructed with various materials from stone to wood. View Ground anchor LRFD from GEOLOGY 2323 at Bandung Institute of Technology. Sankey, Terre Armee This presentation was prepared to provide an overview of Mechanically Stabilized Earth (MSE) wall technology as an introduction to the presentations that followed in the TC218 Workshop. Cantilever Cantilever walls provide lateral earth support solely by the bending and shear strength of the wall and by passive resistance of the soil in which. The wall mass must be sufficient to counteract sliding and overturning forces from the retained soil.



01 Consideration of an Earth-Retaining System. Schedule Annual Maintenance Serving Greater Calgary, Lethbridge, Medicine Hat, Red Deer, Banff. Rock anchors are used commonly as part of retaining walls, and as part of a system to resist movement of a foundation. Face drainage is virtually always used with permanent walls, and very commonly used with temporary walls. This is accomplished by drilling a small hole for the anchor rod to pass through the basement wall, and then excavating a hole outside to place the bearing plate. Anchored walls are the strongest type of retaining wall, and can be combined with other techniques. Drill Tech has installed over 1,000,000 square feet of soldier pile retaining walls, using both driven and drilled beams, with and without tiebacks. We reduce uncertainty and improve the bottom line on projects for highways, waterfronts, industries, commercial and military projects in all 50 states. The bar or strand ties are called permanent ground anchors or tiebacks. If the walls in your basement are bowing or leaning inward, it is a sure sign that your foundation is failing. Retaining walls Example 3. The stem is a vertical cantilever beam, acted on by the horizontal earth pressure. Typical of deeper excavations, 8 feet or more, or if there is an adjacent structure. Use design-bid-build process for construction of the wall. This document is available to the public from the National Technical Information. We have carried out the design of many earth and water retaining structures and have considerable experience in this field. This wall is unusual in that it doesn't rely on dead weight or deep pilings to keep from caving in or shifting. As the site is excavated, a temporary anchor may be needed to help prevent the excavation wall from collapsing. Anchor Wall™ Shoreline Protection System. Earth Retention Systems is a leader in the segmental and MSE retaining wall industry.



SUMMARY REPORT OF RESEARCH ON PERMANENT GROUND ANCHOR WALLS, VOLUME IV: CONCLUSIONS AND RECOMMENDATIONS. The main purpose of geotechnical ground anchors is to prevent horizontal movement, while stabilising retaining structures, including sheet pile, bored concrete pile and steel tubular walls. Because we use only the best plate anchors made by Earth Contact Products, you can be assured that once they are installed, they will last for years. The success of the helical anchor tieback system dates back to decades of similar use of CHANCE® Anchors in the. Water front structures, for example, in building wharfs, quays, and piers. Bored pile retaining walls Bored pile retaining walls are built by assembling a sequence of bored piles, proceeded by excavating away the excess soil. With one end of the tieback secured to the wall, the other end is anchored into the earth with sufficient resistance. It derives its name from the fact that its individual parts behave. 75m high with a width of 1m or 2m depending on height dimensions. CBS T-type retaining walls are designed for applications where a load will be placed on to both sides of the retaining wall. How to Build a Retaining Wall With Crossties. The pressure against an object is greater at the lower levels of the retaining wall because of all the earth on top pressing down. In general, for every 1m increase in wall height, the bottom row basket depth should be increased by half a metre. Key Words Ground anchors, soldier beam and lagging walls, limit equilibrium, earth pressures, axial capacity, tiedowns, seismic design, contracting, specifications 18. The common theme across all our structures is that they all have a "TOUCH OF GREEN" and they are living. We have built a solid and respected reputation within the industry and with our clients. Tied-back retaining walls were used originally as a substitute for braced retaining walls in deep excavations. The 8-foot wall actually needs to be four times stronger. The maintainable filter uses a removable, cleanable geotextile filter cartridge to help extend the life of your retaining wall. • No de-watering for below water-table.



We needed holes in the tie wall before installing anchors. of Keystone Retaining Wall Systems, Inc. After installation, wall anchors can often be tightened over time to further straighten your foundation walls and pull them back to their original position. Generally there are 4 types of retaining walls. Stream Restoration and Stabilization Projects Purpose This technical supplement provides an introduction to the use of sheet pile, types of walls, sheet pile materi-als, classical method of design for wall stability, struc-tural design, specification, and installation of sheet pile for stream restoration and stabilization projects. We used rebar for the posts, billboard tarp and cheap mesh. Face drainage usually consists of synthetic drainage elements placed between the shot-Crete and the retained soil and may be typically 8 to 12 inches wide synthetic strips or. Earth anchors can be used in either temporary or permanent applications. For product specifications, installation instructions, anchor load capacity and pullout strength, please visit our web site https://americanearthanchors. Today, taller retaining walls are increasingly built as composite gravity walls such as: geosynthetic or with precast facing; gabions (stacked steel wire baskets filled with rocks); crib walls (cells built up log cabin style from precast concrete or timber and filled with soil); or soil-nailed walls (soil reinforced in place with steel and concrete rods). REPAIR SERVICE FOR LEANING & BOWING RETAINING WALLS. MSE Modular Block Wall Systems System Manufacturer Approval Number Licensed Producer CLASS I-Height Limited to 40 Feet KeySystem 1 Keystone Retaining Wall Systems, Inc. There are quite a few options for that, but now I am looking at doig an approximately 300' curved retaining wall with a max height of about 12'. CHANCE® helical tieback anchors are pre-manufactured steel anchor elements consisting of a central steel shaft and one or more helical shaped bearing plates. Steel soldier pile walls taller than approximately 20 feet require horizontal whalers and tie backs, as shown in Figure 5, to limit deflection and stresses. The reason is that although there were joints between the retaining walls, the wave preventing board, which was on top of the retaining wall, was connected together. The Perfect Retaining Wall System VERSA-LOK retaining wall systems are cost-effective, easy-to-install, and give you endless design options. The seismic behaviour of retaining walls depends on the total lateral earth pressures that develop dur-ing earthquake shaking. Heavy-duty, galvanized earth anchors are embedded in stable, undisturbed soil outside your foundation wall. Applications of Sheet Pile Walls Sheet pile walls are retaining walls constructed to retain earth, water or any other fill material.



Soldier Pile Walls. However, the most important part of the wall is the part below the ground that anchors it. Read expert tips on how to repair a retaining wall—a landscaping wall that can be used to retain earth after an excavation. Retaining walls are more than just a visual feature. 03-Failure of CBP earth retaining wall Pg. Helical Tiebacks Straighten & Strengthen with Helical Wall Tiebacks. The following text provides a general discussion and design guidelines for these flexible wall. Thus it is also called gravity retaining wall. Hulk Earth Anchors are active mechanical anchors that offer significant economic advantages and represents a major breakthrough in soil anchoring technology. The statistics of the walls include one-third portion above the ground and the rest (two-third) below ground level. Earth Retention systems are utilized to protect adjacent streets, buildings, utilities, etc. 3" & 4" Arrowhead Anchor Anchoring Vineyard Posts 3" & 4" STEEL ANCHORS ARROWHEAD ANCHORS Up To 3,500 pounds of holding power. Distribution Statement No Restrictions. August 2017 4-4-3. The passive resistance at the toe of retaining wall is calculated as Where K p is passive earth pressure coefficient, h is the height from top of soil to bottom of footing at toe. create an intelligent aid for solving retaining wall problems.



If the retaining wall is restrained in the long term, then it should be designed for the At Rest earth pressures. Various types of loads and forces acts on a retaining wall and their calculation is important for its design. Anchors for Retaining Walls. Oscar Orduno, Inc. If swales are designed at the top of the walls, properly line and slope them so water is removed before it can fl ow down behind the walls. 1 of 2 FAILURE OF CONTIGUOUS BORED PILE EARTH RETAINING WALL Type of building work A 4-storey condominium with two basement was to be built on a slope of a hill. But it was truly. Each retaining wall design has its own particular characteristics, making it more suitable for certain applications than others. They are designed to provide resistance against various failure modes, including sliding, overturning, bearing and seismically induced failures. Three main types of retaining walls: 1. It derives its name from the fact that its individual parts behave. Secant pile walls can be successfully installed in a virtually any ground conditions, including grounds that are typically difficult to work with. Tieback anchors are commonly used in earth retention applications such as in repairing failing/tilting retaining walls and seawalls. Board and beam retaining walls can be designed as cantilever walls, alternatively earth anchors or bracing can be utilized to provide additional lateral support. However, the term is most often used to refer to a cantilever retaining wall, which is a freestanding structure without lateral support at its top. Thanks again for checking in and I'll get some regular posts happening throughout the summer. Sting Ray Manta Ray Pitting and Corrosion Report. The position of the gravel piles and the results of inclinometer measurements are shown.



The lateral earth pressure distribution for the design of temporary or permanent anchored walls constructed in cohesionless soils may be determined using equations provided in AASHTO LRFD BDS (2007). However, the most important part of the wall is the part below the ground that anchors it. Retaining Walls in Omaha are Clear Creek Landscapes specialty. The project has started so I thought I would post some pis and comments during the project. Choosing retaining wall materials Just as there are various retaining wall. The Versatility Continue Reading. Permanent Earth Retention. Different types of earth retaining systems can be employed to conduct deep excavation procedure in construction. DiMaggio’s technical areas of specialty include structural foundations, earth retaining structures, ground improvement techniques and engineered earthworks for transportation, building and energy projects, risk management, forensic engineering, dispute resolution and development of technical training programs. Segmental retaining walls can be installed in a wide variety of colors, sizes, and textures. Gravity retaining wall (depends on its weight for resisting lateral earth force because it have a large weigh) 2. Plate Anchors. The selection of earth retaining system depends on the economy, the soil conditions of the site, the safety of adjacent structures, water table conditions and environmental conditions. Retaining walls and reinforced slopes are typically included in projects to minimize construction in wetlands, to widen existing facilities, and to minimize the amount of right of way needed in urban environments. Welcome to ERS Walls. Contact the experts at Southeast Foundation Repair today for a free estimate for foundation repair in Wilmington , NC and nearby locations. Ground-anchored walls are thin concrete retaining walls that are permanently anchored to firm ground by grouted ties. 5 times the overall length of the piling) to existing structures. This is accomplished by drilling a small hole for the anchor rod to pass through the wall.



Tiebacks are installed behind retaining walls to provide lateral support. Permanent Earth Retention. aegfoundation. Allan Block, Mesa. Earth Pressures and Design Considerations of Narrow MSE Walls Ken T. We made a retaining wall/shelf below the rapidobe wall. When a foundation wall is damaged by settling or by lateral pressure from swollen soil it places the entire foundation at risk. Use precast concrete panels for vertical facing elements and coarse aggregate in the. Retaining walls are structure used to retain soil, rock or other materials in a vertical condition. It analisis the stability of the wall based on the loads and the resulting base pressure, sliding and excentricities. The average cost of building a retaining wall is $5,373. By the MOTHER EARTH NEWS editors. The anchors generally founded beyond the "active wedge" of material being retained. With one end of the tieback secured to the wall, the other end is anchored into the earth with sufficient resistance. • Retaining walls • Roadways • Levees / Dams • Earth Retention • Revetments • Bulk heads • Sea walls • Site development • No belled and/or long length grouted bond zones required. Then, the boxes are filled with crushed stone or other coarse granular materials to create a free draining structure. Memo to Designers 5-12 July 2012 5-12 Earth Retaining Systems Using Ground Anchors (I) General Information Common.



This will ensure the stability of the wall despite significant stress. Hayward Baker draws on its extensive experience with the full range of techniques to provide optimal earth retention & shorings solutions for each project. WALLAP is suitable for the analysis of both temporary works, such as sheet pile walls, and permanent works such as reinforced concrete diaphragm walls and contiguous bored pile walls. Helical tiebacks are horizontal rods used to support to strengthen and straighten bowed basement or retaining walls. Zinc plated for moderate corrosion resistance. Sting Ray Manta Ray Pitting and Corrosion Report. Reese Shin Tower Wang. The usual number of helices on. Scroll Down We have developed particular expertise in micropiles, soil retaining walls, tie backs, underpinning, anchoring and rock bolting, slope stabilization, and landslide remediation. The retaining walls are Suitable for a variety of applications such; as earth retention, landscaping, aggregate bays, waste & recycling storage, bulk material, to name a few. I asked about Manta-Ray earth anchors a while back and didn't find anybody who had used them. specifications for ground anchors and for anchored walls. Permanent Earth Retention. This is accomplished by drilling a small hole for the anchor rod to pass through the wall. Join LinkedIn today for free.



We are full service earth-retaining (retaining wall and Paver) in Atlanta, Georgia, USA. Hulk Earth Anchors are active mechanical anchors that offer significant economic advantages and represents a major breakthrough in soil anchoring technology. Discontinuous retaining structures, such as drilled piers, H-piles, or crib walls, can be more. Earth anchors can be used in either temporary or permanent applications. •Nicholson designed and installed a semi-continuous reinforced drilled shaft soldier pile retaining wall with tieback anchors, which relieved pressure on the existing wall and stabilized the slope. This document is available to the public from the National Technical Information. If the structure of your building or home is bowing or cracking, we offer a variety of wall repair options to stabilize your foundation. Consider the distance the rock nails will project behind the wall and any potential conflicts with subsurface obstructions or right of way limitations. A retaining wall provides the structural support to hold the lateral pressure of the earth. > CAD Details > Modular Segmental Retaining Wall Systems Allan Block Corp. We specialize in supplying a variety of earth anchors to assist with your construction projects. Scroll Down We have developed particular expertise in micropiles, soil retaining walls, tie backs, underpinning, anchoring and rock bolting, slope stabilization, and landslide remediation. That’s where we come in. Compared to helical anchors used for tieback walls, there is no need to build pile and lag. We have carried out the design of many earth and water retaining structures and have considerable experience in this field. Klapmuts Concrete and Cape Retaining Systems have obtained the various licenses for marketing numerous retaining wall products such as Terraforce, Loffelstein and Infraset range of products like the Water Loffel and Terrace Blok. Passive earth pressure on embedded anchor plates constitutes a viable resisting force for the design of underground structures. The Anchor™ Highland Stone® Freestanding Wall System by Pavestone is crafted with the same earthen colors and rough-hewn texture that made Highland Stone® a top choice for retaining walls.



Earth Anchors Set (4-Piece)-10075 - The Home Depot. Considerably high retaining wall can be constructed using this type of retaining wall structure system. The retaining wall is located partially or entirely within the Bridge zone (Figure 15. They need to be well designed and built to prevent failure. an arched ceiling (section 71) with identified main sliding surface within the creeping mass. As the excavation progresses, approximately every 3 metres anchors may be used. The possibility of including water pressures has to be considered if sufficient drainage is not provided. Wall anchors are the most versatile wall repair method because they can be used to stabilize walls with a variety of problems, including bowing walls, tipping walls, and walls that are pushing in at the bottom. SupportIT is design and analysis software for modelling the shoring of excavations in stratified soil using sheet pile or soldier pile and lagging walls. Reaction blocks are either precast or cast-in-place around the anchor heads. As with Steel sheet piles, ground anchors can be temporary or permanent, depending on the application – anchors can be ‘passive’ or pre-stressed to 110% of the. Manufactured in an assortment of sizes, Marshalls CPM’s precast concrete L shape retaining walls are ideal for a variety of applications including:. For most retaining walls, the face of the wall should be at least 3 feet in front of the face of the abutment cap. However, they also include an anchorage, which introduce defects specific to the anchor. METHOD OF RETAINING WALL CONSTRUCTION AND ANCHORING Filed Sept. Undermined retaining wall repair with pier and gradebeam system, Helical anchor holddown installation at Marvel Corp. 3 for the backfill. Truline is manufactured only by our parent company, Formtech Enterprises, Inc. Plate Anchors. Earth Retention Systems is a leader in the segmental and MSE retaining wall industry.



Matthews Wall Anchor & Waterproofing Services is your plate anchors experts. It analisis the stability of the wall based on the loads and the resulting base pressure, sliding and excentricities. Bentonite slurry walls and steel sheet pile walls are fairly impervious and can, therefore, experience the build-up of significant hydrostatic pressure, regardless of the groundwater level on the front (open) side of such a wall. VERSA-LOK offers attractive segmental retaining wall systems equally suited for residential, commercial and public works applications: Standard, Accent, Cobble, Harmony, Mosaic, Square Foot, Ultra, Nexus, Brute, Bronco 30H, Bronco 18H and VERSA-Green, a plantable retaining wall system that becomes a living part of your landscape. By submitting this form, you are granting Pavestone permission to Email you. As a general recommendation, the maximum height of a properly built stacked stone retaining wall is 5 feet under ideal conditions—the grade behind the wall is flat and the. ShelterLogic 30 in. “The results are great!. Allan Block Wall. They present significant technical advantages over conventional rigid gravity retaining walls or external bracing systems that result in substantial cost savings and reduced construction period. Design Considerations for MSE Retaining Walls Constructed in Confined Spaces 5. Vertical Tie-Down System with Earth Anchors PDF DWG. Geo-Lock™ Channel Anchors For Extreme Wall Problems Stabilize Extremely Damaged Walls What It Does: The Supportworks Geo-Lock™ Channel Anchor System permanently stabilizes and repairs bowing or tilting foundation walls -- without the cost and disruption of total foundation replacement. The lightweight, easy-to-handle size makes this the perfect solution for small retaining wall and garden planters. Earth anchors can be used in either temporary or permanent applications. Crib Wall Design Basic soil parameters; Unit weight of soil. We specialize in supplying a variety of earth anchors to assist with your construction projects.



Basics of Retaining Wall Design 10 Editionth A Design Guide for Earth Retaining Structures Contents at a glance: 1. 01 Consideration of an Earth-Retaining System. > CAD Details > Modular Segmental Retaining Wall Systems Allan Block Corp. When combined with our mass excavation services, we can provide turnkey urban basement excavations. Lightweight and easily stowed under a seat, it’s the only recovery anchor that works around rocks , on trees , and in the ground. This is accomplished by drilling a small hole for the anchor rod to pass through the wall. Allan Block masonry walls are useful on sites where geogrids are not feasible or cost effective because they rely on a reinforced footing and vertical pilasters to counteract lateral earth pressures. If the walls in your basement are bowing or leaning inward, it is a sure sign that your foundation is failing. Reinforced wall design is very similar to conventional retaining wall design, but with the added consideration of internal stability of the reinforced section. Hulk Earth Anchors are active mechanical anchors that offer significant economic advantages and represents a major breakthrough in soil anchoring technology. Wall anchors work by extending from your wall to the stable, hard packed soil beyond your home. That’s where we come in. Platipus Anchors are known as the market-leading designer, manufacturer and supplier of mechanical earth anchoring products and solutions. Figure 4a,b (from Burland et al 1981) compares the ratios (H/h) of the overall wall height H to the retained height h calcu-. Also known as a ground anchor, percussion driven earth anchor or mechanical anchor, it may be impact driven into the ground or run in spirally, depending on its design and intended force-resistance characteristics. Determination of the grouting anchor pullout force is a key step during the design of anchor-pull retaining wall, but it is mostly determined relied on empirical formula at present, and the rationality and the safety cannot be effectively guaranteed. Standard specification Item 423 Retaining Walls and Item 411 Rock Nail Anchors govern construction of this wall type and are supported by the special specification Prefabricated Soil Drainage Mat. The purpose of all retaining walls is to hold soil behind them. Helical tieback anchors are used in conjunction with a variety of earth retaining systems such as sheet piles and soldier piles in order to provide additional lateral resistance beyond what is achievable by a cantilevered wall.



The Truline wall system offers a better way to build and protect steel-reinforced concrete walls for longer service life of seawalls, bulkheads, retaining walls, cutoff walls, and more. Anchored Bulkhead Retaining Wall. Member on here, U. Sticking Windows & Doors; Tilting Chimney; Sagging Floors. The position of the gravel piles and the results of inclinometer measurements are shown. METHOD OF RETAINING WALL CONSTRUCTION AND ANCHORING Filed Sept. Wall anchors are the most versatile wall repair method because they can be used to stabilize walls with a variety of problems, including bowing walls, tipping walls, and walls that are pushing in at the bottom. Marvel at the age-old craftsmanship each and every random-patterned Mosaic® wall exudes. on the anchors. additional wall height is historically added to the top of I-walls to accommodate future subsidence in soft soils. Cantilever Reinforcement Reinforcement Counterfort 4. It analisis the stability of the wall based on the loads and the resulting base pressure, sliding and excentricities. These include…. Retaining walls can be constructed with various materials from stone to wood. Bar ground anchors are most frequently used to anchor retaining walls, stabilise deep excavations or to anchor tower cranes or tie rods. Needed a little dirt too. These anchors help walls resist pressures that force them forward or cause them to pivot on footing material.



A weep hole filter relieves water pressure and prevents retaining wall failure. Retaining walls are more than just a visual feature. Design stem (tstem, Asstem). They are found in situations with weak soil or rock. Our Anchor Drains are a quick, simple and effective means of reducing hydraulic pressure, water puddling within clay slopes and behind retaining walls. Most soil anchors have working loads of 80 to 400 kips (80,000 – 400,000 lbs. This can happen if the footing toe is too small or if the wall wasn't properly reinforced. Ground anchors are typically constructed with a circular shaft of one or more helixes; a head connects at the opposite end of the anchor, which then connects to the. Earth anchors are used in both temporary or permanent applications, including supporting retaining walls, guyed masts, and circus. Anchors are used to support walls against lateral earth and water pressures in earth retaining structures, to secure landslides, tunnels, shafts and deep excavations. Rock anchors are used commonly as part of retaining walls, and as part of a system to resist movement of a foundation. Segmental retaining walls can be installed in a wide variety of colors, sizes, and textures. Sheet pile walls : Used to build continuous walls for waterfront structures and for temporary construction wall; heights > 6 m if used with anchors. The possibility of including water pressures has to be considered if sufficient drainage is not provided. For tied-back and MSE walls, this is especially critical because the tiebacks and wall reinforcements may need to be skewed around the abutment foundations. 1 1 1 6min. Earth Anchors For Retaining Walls.