中文3700字
Soil nail wall, also known as soil nailing technology, which is installed in situ soil with a relatively dense soil nails, and soil slope surface of sprayed concrete to build a steel mesh surface layer, through the soil nails, the surface layer and in-situ soil the role of the three common slope or retaining wall side. Soil nail walls but also poses a similar gravity in situ reinforced earth retaining structures. And supporting a variety of methods have been compared, it has the construction easy, simple equipment, require little space, excavation and supporting jobs can be parallel, the overall progress of the fast, low cost, as well as pollution, low noise, stable and reliable, social and economic good, and many other advantages, and therefore at home and abroad with the foundation pit slope reinforcement has been widely applied rapidly. Soil nail wall construction technology is a top-down step by step build process, according to the following order: According to design requirements for excavation face, trimmed slope, planted sprayed concrete thickness control signs; jet first layer of concrete; erection of drilling soil nails, grouting, erection of connectors; banding steel net, spray a second layer of concrete; set top of the hill, slope and the foot of the slope of the drainage system.
Soil-nailed law-enforcement: keep as much as possible, significantly higher maximum use of pit wall side of inherent mechanical strength of soil, changing soil structure and system load as part of the bracing. Sprayed concrete under the effect of high pressure gas flow, wherein high-speed soil surface layer and the soil in the spray created between 'embedded solid-effect', and gradually form a completely closed with the excavation shoring systems, spray layer and mounted with a protective layer of and reinforcement of topsoil, so that to avoid exposure to wind and rain erosion, shallow collapse, local spalling, as well as the role of impermeable impermeable. Soil nailing a special control pressure grouting can be reinforced medium greatly improved physical and mechanical properties make it become a new geological body, its solid-solid in the slip plane the deep section of the soil outside the house, its external fixed terminal Spray the surface layer in conjunction with the network as a
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whole may be a tendency to instability in the side wall transferred to the solid-section and its vicinity and to eliminate. Reinforced Mesh sprayed layer can have a better integrity and flexibility, can effectively adjust the spray layer and the stress distribution within the soil nail. Active soil nail retaining soil and with soil together with construction of simple, rapid and timely, flexible applicability, with the digging with sticks, safe and economic characteristics. Its duration is generally poorer than the traditional method to save more than 30-60d, engineering, low cost and 10% -30%, supporting the maximum vertical pit depth has now reached 21.5m, built mud (local miscellaneous fill) pit depth of 10m. This method not only effectively be used for general geotechnical deep excavation shoring, often also used a number of other ancillary support measures, can effectively be used for supporting streaming sand, silt, complex filling, saturated soil, soft soil, etc. adverse geological conditions of the deep excavation. In addition, it is also rapid, reliable and economical method of using the traditional method or improved facilities to be made or have been carried out rescue excavation instability reinforcement.
Of soil nailing and reinforced soil and anchor it seems such as retaining structures, however, the structure of soil nailing and reinforced earth construction, etc. There are many different points, and anchor.
First of all, soil nailing and reinforced soil slope or retaining wall is not the same, mainly reflected in: the construction in different ways. Soil-nailed construction of the distribution of expansion from top to bottom, side excavation while retaining full use of undisturbed soil strength. Reinforced earth structure from bottom to top filling layered construction, filling choice, density and intensity can be controlled; reinforced pull the biggest changes in body pattern is different. In the reinforced earth structure, the general body at the bottom of the tendon force maximum. In the structure of soil nailing, the general range of the central part of the largest force of soil nail, the upper and bottom of the soil nail force small; different deformation properties. Soil Nailing the maximum displacement occurred in the supporting slope at the top or near the top, reinforced earth structure, the maximum displacement at the bottom.
Secondly, soil nailing and bolting or retaining wall is not the same, mainly due to:
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the various parts of the force and the same role. Bolting or retaining wall of the anchor generally anchorage section and free above, the use of sliding surface to provide resistance outside the anchorage section, set the anchor generally prestressed, the free section under uniform tension effect, through the anchor seat passed to the slope of the retaining structures, earth retaining structures greater stiffness, mainly through the provision of resistance by the moment, is one of the main force components. Soil nailing settings generally do not impose pre-tension, but occurs in the soil after a small deformation of the passive force, the size of the force along the uneven distribution of soil nail extension, the middle on both sides of the small, the role of the force at the surface layer than the small, sprayed concrete surface layer is not a major force components, its role is to stabilize the surface of the partial excavation of soil to prevent caving and erosion; setting different densities. In the bolt support in the unit area on the retaining bolt set the number of generally less, for each root anchor construction accuracy and requirements are very stringent. In the soil-nailing, the surface of soil nail retaining a little bit more dense arrangement of individual soil nail construction relatively low accuracy and quality requirements; design of different lengths. In the bolt support, the design requirements must meet the requirements of each root anchor of resistance, so bolt anchorage section require in-depth into the stable layer, the design of a longer length. In soil nailing, the more dense arrangement of soil nail, the large number of interaction with the surrounding soil, to maintain self-reinforced zone of soil stability, and resistance to outside the region reinforced the role of soil pressure, design shorter length. Of course, there are many types of bolts, there are not pre-stressed, the length than the average soil-nail even shorter, but this bolt is mainly used for the tunnel or underground works of the spray-anchor on the length than the average soil-nail is also is shorter, often only 2-4m.
（1）Construction of Soil Nail
Soil nailing is a soil-nail as a major component of the slope of the force supporting technology, which consists of dense soil nail group, has been reinforced in situ soil, sprayed concrete surface layer and the necessary water system components.
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（2）Structural Materials
Steel: steel types, models and sizes should be consistent with design requirements, should adopt the H-or H-class steel workers, reinforced after the purchase should be properly safeguarded to prevent corrosion, production should be transferred straight, rust, oil removal, should be carried out physical and mechanical properties or chemical composition analysis of test welding of steel, should be weldability and welding quality of the test for detection of welding material strength should be greater than the overall strength;
Cement: ordinary portland cement used, label P032.5, if necessary, sulfuric acid resistant cement, alumina cement should not be used. Cement should comply with the provisions of the existing cement standard requirements, there must be a single factory test reports, quality inspection orders, factory card documents, in accordance with its varieties, label, test numbers etc., and inspection and acceptance sampling inspection, by the examination results are reasonableUse. Bags of cement should be properly kept in storage and transportation, rain, moisture, stacked in a certain height from the ground heap shelves, is strictly prohibited and damage throwing throwing bags, prohibited the use of damp or different varieties of mixed cement label. Aggregate: stone and sand material (seeds film, medium-fine sand) should check report cards, the stone test methods and quality standards by JGJ53-92, sand material testing methods and quality standards by JGJ52-92. Particle size of less than 2mm in the sand, sand, clay content by weight not more than 3%, the particle size of less than 12mm gravel or melon tablets, clay content by weight not more than 3%.
Mixing of water: the water without affecting the normal condensation of cement hardening of harmful impurities, may not contain fat, sugar and free acid, etc.; water, PH value is less than four of acidic water and sulfur ion of more than 1% of the water weight of water were shall not be used; the use of tap water or clean water for mixing natural water could be dispensed with for testing.
Quick-setting agent: quick-setting agent is used in J85, 711, or Red Star 1, should be specifically responsible for control, add the weight of 3% of the weight of cement, the machine automatically added by the jet.
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Electrodes: The THJ422.
Concrete mix: In addition to spraying the concrete mix design standards to be attained strength, we must also meet the technical requirements of construction, with the ratio of 1:0.4:2:2 (cement: water: sand: melon pieces), melon seeds piece maximum diameter of not more than 12mm.
Grouting mixture ratio: one-grouting with cement mortar 1:1, the second grouting using water-cement ratio of 0.5 water slurry, cement mortar and cement slurry must be stirred evenly pure, a mixing of the slurry must be initial setting before ( generally 2h) run out.
Early strength and water-reducing agent: According to the nature of projects, using different types of early strength agent, commonly used red star on the 4th, 3F, NC, NNOF, NS2-1 and so on.
（3）Net production of soil nailing and reinforced
Size allowable deviation of soil nail making: the length of ??100mm, curved reposted elsewhere in the paper for free download （4）Drainage System
Soil Nailing appropriate to remove ground water under the conditions of construction, the drainage should take appropriate measures, including surface drainage, internal drainage, as well as supporting the drainage pit in order to avoid saturation of the soil and reduce the role of the hydrostatic layer on the surface pressure.
Excavation around the bracing should be added within the surface finishing, and building drains and cement mortar or concrete surface to the underground water surface infiltration of precipitation. Pit top of the hill near the 2-4m wide and the ground should be properly boosted, and the inside of high external low, easy to run-off away from the slope. In supporting the back surface layer should be inserted in a length of 400-600mm, diameter of not less than the standard 40mm drain out its external side supporting surface layer spacing for 1.5-2m, in order to spray the plot after the surface layer of concrete water discharge. To rule out the accumulated water seepage inside the pit and rain should be set 300mm * 300mm Bottom drains, leads to
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