基坑支护外文文献

1、 Soil nail wall, also known as soil nailing technology, which is of the three common slope or retaining wall side. Soil nail walls butalsoposesasimilargravityinsitureinforcedearthretaining structures. Andsupportingavarietyofmethodshavebeencompared, ithastheconstructioneasy,simpleequipment,requirelit

2、tlespace, excavationandsupportingjobscanbeparallel,theoverallprogress reliable, socialandeconomicgood,and manyotheradvantages, 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 ste

3、p build process, according to the following order: According to design requirements for excavation face, trimmed slope, planted sprayed concrete thickness control signs; grouting,erectionofconnectors;bandingsteelnet,sprayasecond Soil-nailed law-enforcement: keep as much aspossible, significantly hig

4、her maximum use of pit wall side ofinherent mechanical strength of soil, changing soil structure andsystemloadaspartofthebracing.Sprayedconcreteundertheeffectof high pressure gas flow, wherein high-speed soil surface layer and graduallyform acompletelyclosedwiththeexcavationshoringsystems, spray lay

5、er and mounted with a protective layer of andreinforcementoftopsoil,sothattoavoidexposuretowindandrainerosion, shallow collapse, local spalling, as well as the role ofimpermeable impermeable. Soil nailing a special control pressuregrouting can be reinforced medium greatly improved physical andmechan

6、ical properties make it become a new geological body, its conjunction with the network as a whole may be a tendency to its vicinity and to eliminate. Reinforced Mesh sprayed layer canhave abetterintegrityandflexibility,caneffectivelyadjustthespraylayerandthestressdistributionwithinthesoilnail.Active

7、soil nail retaining soil and with soil together with constructionof simple, rapid and timely, flexible applicability, with thedigging with sticks, safe and economic characteristics. Itsduration is generally poorer than the traditional method to save the maximum vertical pit depth has now reached 21.

8、5m, built mud effectively be used for general geotechnical deep excavationshoring, often also used a number of other ancillary supportmeasures, can effectively be used for supporting streaming sand, alsorapid,reliableandeconomicalmethodofusingthetraditionalmethod or improved facilities to be made or

9、 have been carried outrescue excavation instability reinforcement. seems suchas retainingstructures,however,thestructure of soilnailing and reinforced earth construction, etc. There are manydifferent points, and anchor.First of all, soil nailing and reinforced soil construction in different ways. So

10、il-nailed construction of thedistribution ofexpansionfromtoptobottom,sideexcavationwhileretaining full use of undisturbed soil strength. Reinforced earthstructure frombottomtotopfillinglayeredconstruction,fillingchoice, density and intensity can be controlled; reinforced pull ofthesoilnailforcesmall

11、;differentdeformationproperties.SoilNailing the maximum displacement occurred in the supporting slopeatthetopornearthetop,reinforcedearthstructure,themaximumdisplacement at the bottom.Secondly, soil nailing and bolting or retaining and thesamerole.Boltingorretainingwalloftheanchorgenerally provide r

12、esistance outside the anchorage section, set the anchorgenerally prestressed, the free section under uniform tensionstructures, earth retaining structures greater stiffness, mainlythrough the provision of resistance by the moment, is one of themainforcecomponents.Soilnailingsettingsgenerallydonotimp

13、osepre-tension, but occurs in the soil after a small deformation of distribution of soil nail extension, the middle on both sides of to preventcavinganderosion;settingdifferentdensities. Inthe of generally less, for each root anchor construction accuracy andrequirements are very stringent. In the so

14、il-nailing, the surfaceof soil nail retaining a little bit more dense arrangement ofindividual soil nail construction relatively low accuracy andquality requirements; design of different lengths. In the boltsupport,thedesignrequirementsmustmeettherequirementsofeachroot anchor of resistance, so bolt

15、anchorage section require soil nailing, the more dense arrangement of soil nail, the largenumber of interaction with the surrounding soil, to maintainself-reinforced zone of soil stability, and resistance to outsidethe region reinforced the role of soil pressure, design shorterlength. Of course, the

16、re are many types of bolts, there are notpre-stressed, the length than the average soil-nail even shorter,but this bolt is mainly used for the tunnel or underground works of the force supporting technology, which consists of dense soil nail group, has been reinforced in situ soil, sprayed concrete s

17、urface layer and the necessary water system components. Steel: steel types, models and sizes should be consistentwithdesignrequirements,shouldadopttheH-orH-class steel workers, reinforced after the purchase should be properly safeguardedtopreventcorrosion,productionshouldbetransferred straight, rust

18、, 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 ce

19、ment used, label P032.5, if necessary, sulfuric acid resistant cement, alumina cementshouldnotbeused.Cementshouldcomplywiththeprovisions oftheexistingcementstandardrequirements,theremustbeasingle factory test reports, quality inspection orders, factory card documents, in accordance with its varietie

20、s, label, test numbersetc., and inspection and acceptance sampling inspection, by theexamination results are reasonableUse. Bags of cement should beproperly kept in storage and transportation, rain, moisture,prohibited and damage throwing throwing bags, prohibited the useof damp or different varieti

21、es of mixed cement label. medium-fine sand)shouldcheckreportcards,thestonetestmethodsand quality standards by JGJ53-92, sand material testing methodsand quality standards by JGJ52-92. Particle size of less than 2mm by weight not more than 3%.Mixing of water: the water without affecting thenormal con

22、densationofcementhardeningofharmfulimpurities,may weightofwaterwereshallnotbeused;theuseoftapwaterorcleanwater formixingnaturalwatercouldbedispensedwithfortesting.Quick-setting agent: quick-setting agent is used control, add the weight of 3% of the weight of cement, the machineautomatically added by

23、 the jet.Electrodes: The THJ422.Concretemix:Inadditiontosprayingtheconcrete mix designstandardstobeattainedstrength,wemustalsomeetthetechnicalrequirementsofconstruction,withtheratioof1:0.4:2:2 (cement: water: sand: melon pieces), melon seeds piece maximum Grouting mixture ratio: one-grouting with ce

24、mentmortar 1:1, the second grouting using water-cement ratio of 0.5 water slurry,cementmortarandcementslurrymustbestirredevenly pure, a mixing of the slurry must be initial setting before Earlystrengthandwater-reducingagent:According to the nature of projects, using different types of early strength

25、 agent, commonly used red star on the 4th, 3F, NC, NNOF, NS2-1 and Size allowable deviation of soil nail making: the length of ?100mm, curved reposted elsewhere in the paper for free download Soil Nailing appropriate to remove ground waterunder the conditions of construction, the drainage should tak

26、eappropriate measures, including surface drainage, internal on the surface pressure.Excavation around the bracing should be addedwithinthesurfacefinishing,andbuildingdrainsandcementmortaror concrete surface to the underground water surface infiltrationof precipitation. Pit top of the hill near the 2

27、-4m wide and theground should be properly boosted, and the inside of high external plot after the surface layer of concrete water discharge. To ruleout the accumulated water seepage inside the pit and rain should appropriate tobrickandmortarPlasteringusedtopreventleakage, Mechanism of composite soil

28、 nail force. In soil-cement pile on the water, soil pressure, soil nail and soilthroughthemillpassedtothestabilityoftheresistanceFormation nails will be a short retaining body deformation Houtu bound dam. This role is similar to reinforced earth retaining pit; nomatterwhatformofconstructionofsoilnai

29、l (hole-drillingmethod, channels are grouting holes, which not only formed a soil groutingnailretainingwallandtheformationoffrictionbetweenthebelt, groutingintheformofreinforcedretainingHoutubody,sucharolesimilar to the mechanism of compaction grouting.TheprocessofsoilnailforceMeasurementsshowed the

30、 completionofgroutinggroutingofthebondingbetweenthebody unaffected by power.Phase II: grouting body of the soil nail bondingintheformation,withtheexcavationdepthincreases,soilnailing similar to non - Free-form deformation of the soil anchor segmentnearthesurfacelayeratthebiggestrally,thesubsequentde

31、creasegradually.The third phase: excavation of sufficient depth, distribution is similar to reinforced earth retaining wall in thestretch.土钉墙又称为土钉支护技术，它是在原位土中敷设较为密集土钉，并 在土边坡表面构筑钢丝网喷射混凝土面层，通过土钉、面层和原位土体三 者共同作用而支护边坡或边壁。土钉墙体同时也构成了一个就地加固类似 需要场地小，开挖及支护作业可以并行、总体进度快、成本低，以及无污 染、噪声小、稳定可靠、社会效益及经济效益好等许多优点，因而在国内

32、 外边坡加固及基坑支护中得到了广泛迅速应用。土钉墙施工技术是一种由上而下分步修建过程，可按下列顺序进行: 按设计要求开挖工作面，修整边坡，埋设喷射混凝土厚度控制标志;喷射 第一层混凝土;钻孔安设土钉、注浆、安设连接件;绑扎钢筋网，喷射第二 层混凝土;设置坡顶、坡面和坡脚排水系统。土钉支护法:以尽可能保持、显著提高、最大限度地利用基坑边壁土 体固有力学强度，变土体荷载为支护结构体系一部分。喷射混凝土在高压 气流作用下高速喷向土层表面，在喷层及土层间产生“嵌固效应”，并随 开挖逐步形成全封闭支护系统，喷层及嵌固层同具有保护和加固表层土， 使之避免风化和雨水冲刷、浅层坍塌、局部剥落，以及隔水防渗作用

33、。土 钉特殊控压注浆可使被加固介质物理力学性能大为改善并使之成为一种 新地质体，其内固段深固于滑移面之外土体内部，其外固端同喷网面层联 为一体，可把边壁不稳定倾向转移到内固段及其附近并消除。钢筋网可使 喷层具有更好整体性和柔性，能有效地调整喷层及土钉内应力分布。土钉 主动支护土体并及土体共同作用，具有施工简便、快速及时，机动灵活、 适用性强、随挖随支、安全经济等特点。其工期一般比传统法节省30-60d以上，工程造价低10%-30%，支护最大垂直坑深目前已达到21.5m，建成 淤泥(局部杂填土)基坑深达10m。该方法不仅能有效地用于一般岩土深基 坑工程支护，而且通常还采用一些其他辅助支护措施，能

34、有效地用于支护 流砂、淤泥、复杂填土、饱和土、软土等不良地质条件下深基坑。此外， 它还能快速、可靠、经济地对采用传统法或改良法施作将要或已经失稳基 坑进行抢险加固处理。土钉支护似乎及加筋土和锚杆等挡土结构一样，然而土钉支护在结构 施工等方面及加筋土和锚杆有许多不同点。首先，土钉支护及加筋土边坡或挡墙不相同，主要表现在:施工方法 不同。土钉支扩从上到下分布进行修建，边开挖边支护，充分利用原状土 强度。加筋土结构由下到上分层填土构筑，填料可以选择，密实度和强度 可以控制;加筋体最大拉力变化规律不同。在加筋土结构中，一般处于下 部筋体受力最大。在土钉支护结构中，一般介于中部土钉受力最大，上部 和底部

35、土钉受力较小;变形性能不同。土钉支护最大位移发生在支护边坡 顶部或接近顶部，加筋土结构最大位移在底部。其次，土钉支护及锚杆支护或挡墙也不相同，主要在于:各部分受力 和作用不同。锚杆支护或挡墙中锚杆一般都有锚固段和自由段，利用滑动 面以外锚固段提供抗力，设置锚杆一般要施加预应力，自由段受到均匀拉 力作用，通过锚座传递到坡面挡土构件上，挡土构件刚度较大，主要通过 受弯矩提供抗力，是主要受力部件之一。土钉设置后一般不施加预拉力， 只是在土体发生微小变形后才被动受力，受力大小沿土钉延长分布不均 匀，中间大两边小，所作用在面层上力较小，喷射混凝土面层不是主要受力部件，其作用是稳定开挖面上局部土体，防止崩

36、落和受到侵蚀;设置密 度不同。在锚杆支护中，单位支护面积上设置锚杆数量通常较少，对每根 锚杆施工精度和要求都十分严格。在土钉支护中，支护面上土钉排列得较 密，对单个土钉施工精度和质量要求相对较低;设计长度不同。在锚杆支 护中，设计要求每根锚杆都要达到要求抗力，所以锚杆锚固段需要深入到 稳定土层中，设计长度较长。在土钉支护中，土钉排列较密，数量众多， 及周围土层共同作用，能够保持加固区土体自身稳定，并抵抗加固区以外 土压力作用，设计长度较短。当然，锚杆有许多种类，也有不加预应力、 长度比一般土钉还要短，但这种锚杆主要用于隧道或地下工程喷锚支护 上，长度比一般土钉还要短，常用只有2-4m。（1）土钉墙结构组成土钉支护是以土钉作为主要受力构件边坡支护技术，它由密集土钉 群、被加固原位土体、喷射混凝土面层和必要防水系统组成。（2）土钉墙结构材料 级钢筋，钢筋购进后应妥善保管，防止锈蚀，制作时应调直、除锈、除油， 应进行物理力学性能或化学成份分析试验，焊接用钢材，应作可焊性和焊 接质量试验检测其焊接强度应大于材料整体强度;水泥:采用普通硅酸盐水泥，标号P032.5，必要时采用抗硫酸水泥， 不得使用高铝水泥。水泥应符合现行水泥标准规定要求，必须有制造厂试 验报告单、质量检验单、出厂证等证明文件，并按其品种、标号、试验编 号等进行检查验收并取样检验，按检验结果合理使用。袋