深基坑土钉墙支护施工工法关键技术

'深基坑土钉墙支护施工工法关键技术山西太行建设开发有限公司一、概述1、随近年来，着国内建设项目逐年增多，高层建筑项目比重日趋增涨，高层建筑一般情况下均设有地下室、设备层、车库或人防地下室，深基坑开挖作为建筑施工的重要组成部分，随着城市市区内建筑物逐渐密集，新旧建筑物紧挨着的情况出现逐渐增多，往往在基坑施工过程中场地比较狭小，无法按照土质及深度正常放坡，经常需要用到土钉墙支护。2、本工法主要阐述深基坑土钉墙施工工法。二、深基坑土钉墙施工工法关键技术1、以太原市太化六千平项目1#及3#住宅楼深基坑支护工程为例：该工程1#、3#楼基坑深度-7.87m，北面因为临近已有3层住宅楼，基坑在开挖时不能按照土质及规范要求设置安全边坡。首先采用《理正深基坑计算软件》计算基坑开挖过程中土体整体稳定性验算，其中其中第一级开挖到-2.7m；第二级开挖到-4.2m，第三极开挖到-5.7m，第四级开挖到-7.87m。第一级至第四级采用土钉墙支护。第二步采用《Nail5.0土钉墙支护结构设计计算软件》计算边坡土体的受力情况并确定土钉墙的设计方案。2、根据地质条件、工程结构、基坑开挖深度以及周边环境、土钉墙设计方案组织专家论证，优化支护方案。三、工艺流程：Endof2015ICountyfilemadepoor......Million,sometimeago,wefollowprovincialandmunicipalrequirementsforfilingstatecardpoor"lookingback"activities,returndoesnotmeettheconditionsofthepoor......Million,newlyaddedtoeligiblepoorpeople......People,throughaccurateidentification,filingStateremainingcardinourCountypoor......Millionpeople.Thisoriginalworkaccuratelyenough,sometownsStreet,broadstrokes,statisticaldayuemo.Someoftheso-called"poor"areassociates,friendsandfamily.Ifsuchpoorlistannounced,willbringalotofnegativeeffect.Wemustrecognizetheimportanceofaccurateidentification,politicalnatureandseriousness,don"ttakeitlightly,andsloppy.Next,youneedthepreciseidentificationofthepoorfurtherandtofocuson"threeclear":first,wemustclearthenumber.Didtakealookatthemissing,thereisnoreturn,thereisnowrongNano,trulynatryna,fallstooneperson.Second,toclarifystatus.Whetherinpoorvillages,thepoororthepoor,toadetailedregistration,fullyandaccuratelymasterthepoorfamilies,livingconditions,accesstoemployment,sourcesofincome,povertylevel,andsoon.Third,toclearreasons.Wasduetodisasters,disease,duetoobjectivefactorssuchaslearning,oristheirlackofcapacity,lackofenrichmentopportunities,orlazy,andwasnotattending,arefaithfullyreflectedtoensurethathouseholdsdonotleak,amanfalls,第7页共8页 首先进行现场勘测，并根据地质条件、工程结构、基坑开挖深度以及周边环境确定初步方案，经过受力验算、专家论证后，进行开挖第一级土方，第一级土方开挖完后，施工第一级土钉墙。第一级土钉墙施工完后再进行第二级土方开挖，以此类推。施工过程中，每道工序都严格按照施工方案及相关规范进行，在基坑回填完以前每三天要对周围地面、道路、建筑物处监测点沉降、位移变形进行观测。工艺流程如下图：四、控制要点1、施工前应按设计单位提出的设计文件、岩土工程勘察报告及《建筑基坑支护技术规程》等制定实施性的专项施工方案，并组织专家论证，同时根据专家论证结果优化专项方案。2、Endof2015ICountyfilemadepoor......Million,sometimeago,wefollowprovincialandmunicipalrequirementsforfilingstatecardpoor"lookingback"activities,returndoesnotmeettheconditionsofthepoor......Million,newlyaddedtoeligiblepoorpeople......People,throughaccurateidentification,filingStateremainingcardinourCountypoor......Millionpeople.Thisoriginalworkaccuratelyenough,sometownsStreet,broadstrokes,statisticaldayuemo.Someoftheso-called"poor"areassociates,friendsandfamily.Ifsuchpoorlistannounced,willbringalotofnegativeeffect.Wemustrecognizetheimportanceofaccurateidentification,politicalnatureandseriousness,don"ttakeitlightly,andsloppy.Next,youneedthepreciseidentificationofthepoorfurtherandtofocuson"threeclear":first,wemustclearthenumber.Didtakealookatthemissing,thereisnoreturn,thereisnowrongNano,trulynatryna,fallstooneperson.Second,toclarifystatus.Whetherinpoorvillages,thepoororthepoor,toadetailedregistration,fullyandaccuratelymasterthepoorfamilies,livingconditions,accesstoemployment,sourcesofincome,povertylevel,andsoon.Third,toclearreasons.Wasduetodisasters,disease,duetoobjectivefactorssuchaslearning,oristheirlackofcapacity,lackofenrichmentopportunities,orlazy,andwasnotattending,arefaithfullyreflectedtoensurethathouseholdsdonotleak,amanfalls,第7页共8页 土钉墙支护结构是一种原位土体加固技术，利用安设或打入基坑边坡土体内的土钉、网喷射混凝土面层及原状土三者共同受力，增强了土体破坏延性，将土体加固成能自稳的重力式的挡土结构。3、土钉墙的质量要求3.1主控项目3.1.1土钉长度：±30mm。尺量检查。3.1.2土钉锁定力：符合设计要求。现场抽样实测。3.2一般项目：3.2.1土钉位置：±100mm。尺量检查。3.2.2钻孔倾斜度：±1°。测钻机倾角。3.2.3浆体强度：符合设计要求。取样检验，检查试验报告。3.2.4注浆量：>1。实际注浆量大于理论计算量。检查计量数据。3.2.5土钉墙面厚度：±10mm。尺量检查。符合设计要求。3.2.6墙体强度：符合设计要求。取样检验。检查试验报告。4、每层挖土深度与土钉垂直间距相匹配，保证每层土方开挖的超挖量小于0.5m，一则便于土钉施工，二则避免超挖造成边坡塌方，每层土开挖后,应修平基坑壁，并在12小时内完成该层土钉及喷层施工，以防塌孔及边坡失稳。5、上层土钉施工后，养护48小时，同时必须在本层坡面土钉墙施工结束并达到设计强度的50%后，才能进行下一层土方开挖，并在下层土方开挖时注意对上层护坡坡面及土钉的保护，避免碰触已施工完的护坡坡面及土钉。6、土钉与联系钢筋、网片、井形垫块应焊接牢固，单向焊缝长度不小于30mm，且土钉露出岩土面的长度不应大于喷层厚度；Endof2015ICountyfilemadepoor......Million,sometimeago,wefollowprovincialandmunicipalrequirementsforfilingstatecardpoor"lookingback"activities,returndoesnotmeettheconditionsofthepoor......Million,newlyaddedtoeligiblepoorpeople......People,throughaccurateidentification,filingStateremainingcardinourCountypoor......Millionpeople.Thisoriginalworkaccuratelyenough,sometownsStreet,broadstrokes,statisticaldayuemo.Someoftheso-called"poor"areassociates,friendsandfamily.Ifsuchpoorlistannounced,willbringalotofnegativeeffect.Wemustrecognizetheimportanceofaccurateidentification,politicalnatureandseriousness,don"ttakeitlightly,andsloppy.Next,youneedthepreciseidentificationofthepoorfurtherandtofocuson"threeclear":first,wemustclearthenumber.Didtakealookatthemissing,thereisnoreturn,thereisnowrongNano,trulynatryna,fallstooneperson.Second,toclarifystatus.Whetherinpoorvillages,thepoororthepoor,toadetailedregistration,fullyandaccuratelymasterthepoorfamilies,livingconditions,accesstoemployment,sourcesofincome,povertylevel,andsoon.Third,toclearreasons.Wasduetodisasters,disease,duetoobjectivefactorssuchaslearning,oristheirlackofcapacity,lackofenrichmentopportunities,orlazy,andwasnotattending,arefaithfullyreflectedtoensurethathouseholdsdonotleak,amanfalls,第7页共8页 7、土钉注浆采用掺速凝剂的32.5级复合硅酸盐水泥。注浆孔直径8～10mm，注浆孔间距500mm（梅花状布置），水灰比0.5，每延米注浆量0.025立方米。拟采用二次注浆工艺进行注浆：第一次注入水泥浆（注浆压力0.6-0.8MPa），填充饱满，待初凝后第二次压注纯水泥浆（注浆压力小于等于上覆压力的两～三倍）。注浆时应先高速低压孔底注浆，当水泥浆从孔口冒出后再低速高压从孔口注浆，浆液注满后应保持压力约5分钟。8、喷射混凝土采用C20混凝土进行喷射，喷射砼施工应满足《锚杆喷射混凝土支护技术规范》（GB50086-2001）规定，粗骨料粒径5-10mm，加速凝剂，喷层初凝小于10分钟，终凝小于30分钟，100mm厚喷层分二次施工。第一次30mm，第二次70mm。喷射厚度不应低于设计值，喷砼必须覆盖钢筋网。喷射顺序相当讲究，应当采取自上而下分段进行，这样可有效地避免混凝土因自重而产生裂纹和脱落，合理地划分喷射区段，保证喷射质量，减少喷射回弹损失，提高功效。喷射混凝土采取每500m2取一组混凝土试块。9、变形观测9.1施工期间在坡顶设变形观测点，观测点固定铝箔纸。观测点间距大约15m。且每边不少于3点。9.2基准点的设置：基准点设在平行于基坑边线并通过观测点或离观测点距离较近的视线上，根据现场条件，基准点的位置应离开基坑边线一定距离设在稳定或相对稳定的位置，每条观测线上至少1个工作基点。Endof2015ICountyfilemadepoor......Million,sometimeago,wefollowprovincialandmunicipalrequirementsforfilingstatecardpoor"lookingback"activities,returndoesnotmeettheconditionsofthepoor......Million,newlyaddedtoeligiblepoorpeople......People,throughaccurateidentification,filingStateremainingcardinourCountypoor......Millionpeople.Thisoriginalworkaccuratelyenough,sometownsStreet,broadstrokes,statisticaldayuemo.Someoftheso-called"poor"areassociates,friendsandfamily.Ifsuchpoorlistannounced,willbringalotofnegativeeffect.Wemustrecognizetheimportanceofaccurateidentification,politicalnatureandseriousness,don"ttakeitlightly,andsloppy.Next,youneedthepreciseidentificationofthepoorfurtherandtofocuson"threeclear":first,wemustclearthenumber.Didtakealookatthemissing,thereisnoreturn,thereisnowrongNano,trulynatryna,fallstooneperson.Second,toclarifystatus.Whetherinpoorvillages,thepoororthepoor,toadetailedregistration,fullyandaccuratelymasterthepoorfamilies,livingconditions,accesstoemployment,sourcesofincome,povertylevel,andsoon.Third,toclearreasons.Wasduetodisasters,disease,duetoobjectivefactorssuchaslearning,oristheirlackofcapacity,lackofenrichmentopportunities,orlazy,andwasnotattending,arefaithfullyreflectedtoensurethathouseholdsdonotleak,amanfalls,第7页共8页 9.3检核点的设置：检核点应选设在变形影响范围以外便于长期保存的稳定位置。对于每个基准点布设的检核点不得少于2个。9.4定向点的设置：在通过工作基点的视线上、基坑对面的稳定建筑物或围墙上或地面上设置定向点，作为观测视线定向的依据。定向点的设置数量与工作基点对应。监测警戒值表项目预警值备注坑外地表沉降20mm3mm/d(连续2天)临近房屋位移10mm2mm/d(连续2天)刚性压力管线10mm2mm/d(连续2天)刚性非压力管线10mm3mm/d(连续2天)柔性管线15mm3mm/d(连续2天)基坑周边堆载堆载超过规定每天24小时巡查9.5基坑开挖时开始对土钉墙及基坑进行变形观测，观测要保持连续性，在基坑开挖阶段每天至少观测1次，基坑底板浇筑完成后3天观测一次，如遇下雨天气，每天派专人进行兼测。五、深基坑土钉墙支护施工工法优点1、深基坑土钉墙支护是土钉、钢丝网、喷射混凝土相结合的联合支护方式，其具有很大的灵活性，特别是在周边环境复杂的情况下，因所需设备简单、所需场地较小而具有较大的优越性。2、土钉墙的特点是通过原位土体加固，充分利用原位土体的自稳能力，而不是用支护结构来挡土，因而工程造价大幅度降低，比护坡桩支护节约费用30%-50%，比地下连续墙节约费用40%-60%，施工工期短50%以上。六、应用效果Endof2015ICountyfilemadepoor......Million,sometimeago,wefollowprovincialandmunicipalrequirementsforfilingstatecardpoor"lookingback"activities,returndoesnotmeettheconditionsofthepoor......Million,newlyaddedtoeligiblepoorpeople......People,throughaccurateidentification,filingStateremainingcardinourCountypoor......Millionpeople.Thisoriginalworkaccuratelyenough,sometownsStreet,broadstrokes,statisticaldayuemo.Someoftheso-called"poor"areassociates,friendsandfamily.Ifsuchpoorlistannounced,willbringalotofnegativeeffect.Wemustrecognizetheimportanceofaccurateidentification,politicalnatureandseriousness,don"ttakeitlightly,andsloppy.Next,youneedthepreciseidentificationofthepoorfurtherandtofocuson"threeclear":first,wemustclearthenumber.Didtakealookatthemissing,thereisnoreturn,thereisnowrongNano,trulynatryna,fallstooneperson.Second,toclarifystatus.Whetherinpoorvillages,thepoororthepoor,toadetailedregistration,fullyandaccuratelymasterthepoorfamilies,livingconditions,accesstoemployment,sourcesofincome,povertylevel,andsoon.Third,toclearreasons.Wasduetodisasters,disease,duetoobjectivefactorssuchaslearning,oristheirlackofcapacity,lackofenrichmentopportunities,orlazy,andwasnotattending,arefaithfullyreflectedtoensurethathouseholdsdonotleak,amanfalls,第7页共8页 位于太原市晋源区金盛镇新村的太化六千平项目工程位于基坑开挖深度7.87m，主要分三级开挖，其中第一级开挖到-2.7m；第二级开挖到-4.2m，第三极开挖到-5.7m，第四级开挖到-7.87m。四级均采用土钉墙支护，针对该工程的特殊性，经组织专家论证，采用土钉墙分层开挖的施工方案可行，并在施工中得到了验证。从施工过程一直到后期观测，结构均未出现沉降及偏移变形，取得了预期的效果。如图：Endof2015ICountyfilemadepoor......Million,sometimeago,wefollowprovincialandmunicipalrequirementsforfilingstatecardpoor"lookingback"activities,returndoesnotmeettheconditionsofthepoor......Million,newlyaddedtoeligiblepoorpeople......People,throughaccurateidentification,filingStateremainingcardinourCountypoor......Millionpeople.Thisoriginalworkaccuratelyenough,sometownsStreet,broadstrokes,statisticaldayuemo.Someoftheso-called"poor"areassociates,friendsandfamily.Ifsuchpoorlistannounced,willbringalotofnegativeeffect.Wemustrecognizetheimportanceofaccurateidentification,politicalnatureandseriousness,don"ttakeitlightly,andsloppy.Next,youneedthepreciseidentificationofthepoorfurtherandtofocuson"threeclear":first,wemustclearthenumber.Didtakealookatthemissing,thereisnoreturn,thereisnowrongNano,trulynatryna,fallstooneperson.Second,toclarifystatus.Whetherinpoorvillages,thepoororthepoor,toadetailedregistration,fullyandaccuratelymasterthepoorfamilies,livingconditions,accesstoemployment,sourcesofincome,povertylevel,andsoon.Third,toclearreasons.Wasduetodisasters,disease,duetoobjectivefactorssuchaslearning,oristheirlackofcapacity,lackofenrichmentopportunities,orlazy,andwasnotattending,arefaithfullyreflectedtoensurethathouseholdsdonotleak,amanfalls,第7页共8页 下面是一组施工图片：Endof2015ICountyfilemadepoor......Million,sometimeago,wefollowprovincialandmunicipalrequirementsforfilingstatecardpoor"lookingback"activities,returndoesnotmeettheconditionsofthepoor......Million,newlyaddedtoeligiblepoorpeople......People,throughaccurateidentification,filingStateremainingcardinourCountypoor......Millionpeople.Thisoriginalworkaccuratelyenough,sometownsStreet,broadstrokes,statisticaldayuemo.Someoftheso-called"poor"areassociates,friendsandfamily.Ifsuchpoorlistannounced,willbringalotofnegativeeffect.Wemustrecognizetheimportanceofaccurateidentification,politicalnatureandseriousness,don"ttakeitlightly,andsloppy.Next,youneedthepreciseidentificationofthepoorfurtherandtofocuson"threeclear":first,wemustclearthenumber.Didtakealookatthemissing,thereisnoreturn,thereisnowrongNano,trulynatryna,fallstooneperson.Second,toclarifystatus.Whetherinpoorvillages,thepoororthepoor,toadetailedregistration,fullyandaccuratelymasterthepoorfamilies,livingconditions,accesstoemployment,sourcesofincome,povertylevel,andsoon.Third,toclearreasons.Wasduetodisasters,disease,duetoobjectivefactorssuchaslearning,oristheirlackofcapacity,lackofenrichmentopportunities,orlazy,andwasnotattending,arefaithfullyreflectedtoensurethathouseholdsdonotleak,amanfalls,第7页共8页 七、推广应用1、本工法适用于施工过程中场地比较狭小，无法按照土质及深度正常放坡，基坑开挖深度大的工程。2、本工法适用于工程造价控制严格、工期紧张、质量要求高的工程。Endof2015ICountyfilemadepoor......Million,sometimeago,wefollowprovincialandmunicipalrequirementsforfilingstatecardpoor"lookingback"activities,returndoesnotmeettheconditionsofthepoor......Million,newlyaddedtoeligiblepoorpeople......People,throughaccurateidentification,filingStateremainingcardinourCountypoor......Millionpeople.Thisoriginalworkaccuratelyenough,sometownsStreet,broadstrokes,statisticaldayuemo.Someoftheso-called"poor"areassociates,friendsandfamily.Ifsuchpoorlistannounced,willbringalotofnegativeeffect.Wemustrecognizetheimportanceofaccurateidentification,politicalnatureandseriousness,don"ttakeitlightly,andsloppy.Next,youneedthepreciseidentificationofthepoorfurtherandtofocuson"threeclear":first,wemustclearthenumber.Didtakealookatthemissing,thereisnoreturn,thereisnowrongNano,trulynatryna,fallstooneperson.Second,toclarifystatus.Whetherinpoorvillages,thepoororthepoor,toadetailedregistration,fullyandaccuratelymasterthepoorfamilies,livingconditions,accesstoemployment,sourcesofincome,povertylevel,andsoon.Third,toclearreasons.Wasduetodisasters,disease,duetoobjectivefactorssuchaslearning,oristheirlackofcapacity,lackofenrichmentopportunities,orlazy,andwasnotattending,arefaithfullyreflectedtoensurethathouseholdsdonotleak,amanfalls,第7页共8页'