《第石灰桩课程学习.pptx》由会员分享，可在线阅读，更多相关《第石灰桩课程学习.pptx（50页珍藏版）》请在taowenge.com淘文阁网|工程机械CAD图纸|机械工程制图|CAD装配图下载|SolidWorks_CaTia_CAD_UG_PROE_设计图分享下载上搜索。
1、会计学1第第 石灰石灰(shhu)桩桩第一页，共50页。工人在用洛阳(lu yn)铲进行石灰桩成孔第1页/共50页第二页，共50页。工人用推土铁钎工人用推土铁钎(ti qin)将洛阳铲带出的土刮除将洛阳铲带出的土刮除第2页/共50页第三页，共50页。工人在室内进行工人在室内进行(jnxng)石灰石灰桩施工桩施工第3页/共50页第四页，共50页。石灰桩孔径石灰桩孔径(kngjng)d=300mm，桩间距，桩间距s800mm第4页/共50页第五页，共50页。人工人工(rngng)洛阳铲洛阳铲第5页/共50页第六页，共50页。三名工人(gng rn)正在夯填石灰桩第6页/共50页第七页，共50页。夯
2、填石灰(shhu)桩所用的夯锤（夯板）第7页/共50页第八页，共50页。夯填石灰(shhu)桩所用的夯锤（夯板）第8页/共50页第九页，共50页。运到施工现场的生石灰块运到施工现场的生石灰块第9页/共50页第十页，共50页。运到施工现场的粉煤灰运到施工现场的粉煤灰第10页/共50页第十一页，共50页。工人工人(gng rn)正在拌合生石灰块正在拌合生石灰块与粉煤灰与粉煤灰第11页/共50页第十二页，共50页。量孔器（测量(cling)石灰桩孔径及孔深）第12页/共50页第十三页，共50页。量孔器（测量(cling)石灰桩孔径及孔深）第13页/共50页第十四页，共50页。n n 石灰桩法适用于处
3、理饱石灰桩法适用于处理饱和黏性土、淤泥、淤泥质土、和黏性土、淤泥、淤泥质土、素填土和杂填土等地基；用素填土和杂填土等地基；用于地下水位以上于地下水位以上(yshng)的的土层时，宜增加掺合料的含土层时，宜增加掺合料的含水量并减少生石灰用量，或水量并减少生石灰用量，或采取土层浸水等措施。采取土层浸水等措施。第14页/共50页第十五页，共50页。10.2 10.2 加固加固(ji)(ji)原理原理10.2 Mechanism of 10.2 Mechanism of ReinforcementReinforcement 一、物理一、物理一、物理一、物理(wl(wl)加固作用加固作用加固作用加固作用
4、 1 1 挤密作用挤密作用挤密作用挤密作用 （1 1）成桩中挤密桩间土）成桩中挤密桩间土）成桩中挤密桩间土）成桩中挤密桩间土 （2 2）生石灰吸水膨胀挤密桩间土）生石灰吸水膨胀挤密桩间土）生石灰吸水膨胀挤密桩间土）生石灰吸水膨胀挤密桩间土 2 2 桩和地基土的高温效应桩和地基土的高温效应桩和地基土的高温效应桩和地基土的高温效应 3 3 置换作用置换作用置换作用置换作用 4 4 排水固结作用排水固结作用排水固结作用排水固结作用 5 5 加固层的减载作用加固层的减载作用加固层的减载作用加固层的减载作用第15页/共50页第十六页，共50页。二、石灰桩的化学加固作用二、石灰桩的化学加固作用 1 桩体材
5、料的胶凝反应桩体材料的胶凝反应 2 石灰与桩周土的化学反应石灰与桩周土的化学反应(huxu fnyng)（1）离子化作用（熟石灰的吸）离子化作用（熟石灰的吸水作用）水作用）（2）离子交换）离子交换 （3）固结反应）固结反应 （4）石灰的碳酸化）石灰的碳酸化第16页/共50页第十七页，共50页。一、设计参数及技术要点一、设计参数及技术要点(yodin)1 桩径桩径 一般为一般为300400mm，当排，当排土成孔时，实际桩径取土成孔时，实际桩径取1.11.2倍设计直径。倍设计直径。2 桩长桩长 洛阳铲成孔不宜超过洛阳铲成孔不宜超过6m，机械成孔管外投料时，不宜超机械成孔管外投料时，不宜超过过8m。
6、10.3 10.3 设计设计(shj)(shj)计计算算10.3 Design 10.3 Design ProcedureProcedure第17页/共50页第十八页，共50页。n n 3 桩距桩距n n 可取可取23倍成孔直径。倍成孔直径。n n 4 桩体抗压强度桩体抗压强度n n 可取可取350500kPa。n n 5 桩间土承载力桩间土承载力n n 与置换与置换(zhhun)率、施率、施工工艺和土质情况有关。可取工工艺和土质情况有关。可取天然地基承载力的天然地基承载力的1.051.20倍。土质软弱或置换倍。土质软弱或置换(zhhun)率大时取高值。率大时取高值。第18页/共50页第十九页
7、，共50页。n n 6 桩土应力比桩土应力比n n 可取可取34，长桩取大值。，长桩取大值。n n 7 复合地基承载力复合地基承载力n n 复合地基承载力特征值不复合地基承载力特征值不宜超过宜超过160kPa。n n 8 布桩布桩n n 可仅布置可仅布置(bzh)在基础底在基础底面下，当基底土的承载力特征面下，当基底土的承载力特征值小于值小于70kPa时，宜在基础以时，宜在基础以外布置外布置(bzh)12排围护桩。排围护桩。第19页/共50页第二十页，共50页。n n 9 垫层垫层n n 当地基需要排水通道时，当地基需要排水通道时，可在桩顶以上设可在桩顶以上设200300mm厚的砂石垫层。厚的
8、砂石垫层。n n 10 桩身材料配合比桩身材料配合比n n 生石灰与掺合料的体积生石灰与掺合料的体积比可选用比可选用(xunyng)1：1或或1：2，对淤泥、淤泥质土、填，对淤泥、淤泥质土、填土可适当增加生石灰用量。土可适当增加生石灰用量。第20页/共50页第二十一页，共50页。二、石灰桩复合地基承载力计二、石灰桩复合地基承载力计算算 面积置换面积置换(zhhun)率率m应应取膨胀后的桩面积计算，即取取膨胀后的桩面积计算，即取1.11.2倍成孔直径。倍成孔直径。第21页/共50页第二十二页，共50页。三、石灰桩复合地基沉降计算三、石灰桩复合地基沉降计算 石灰桩复合土层的压缩模石灰桩复合土层的压
9、缩模量宜通过桩身及桩间土压缩试量宜通过桩身及桩间土压缩试验确定，初步设计时可按下式验确定，初步设计时可按下式估算：估算：式中式中 Es为天然土的压缩模量为天然土的压缩模量（MPa），），系数系数(xsh)可取可取1.11.3，成孔对桩周土挤密效应好或置成孔对桩周土挤密效应好或置换率大时取高值。换率大时取高值。第22页/共50页第二十三页，共50页。10.4 10.4 施工施工(sh gng)(sh gng)10.4 Construction10.4 Construction 一、施工工艺一、施工工艺 1 管外投料法管外投料法 2 管内管内(un ni)投料法投料法 3 挖孔投料法挖孔投料法第2
10、3页/共50页第二十四页，共50页。n n二、施工质量控制二、施工质量控制二、施工质量控制二、施工质量控制n n 1 1 石灰材料应选用新鲜生石灰块，石灰材料应选用新鲜生石灰块，石灰材料应选用新鲜生石灰块，石灰材料应选用新鲜生石灰块，有效氧化钙含量不宜低于有效氧化钙含量不宜低于有效氧化钙含量不宜低于有效氧化钙含量不宜低于7070，粒径，粒径，粒径，粒径不应大于不应大于不应大于不应大于70mm70mm，含粉量不宜超过，含粉量不宜超过，含粉量不宜超过，含粉量不宜超过1515。n n 2 2 掺合料含水量宜控制在掺合料含水量宜控制在掺合料含水量宜控制在掺合料含水量宜控制在3030左右。左右。左右。左
11、右。n n 3 3 填料时必须分段压（夯）实，人填料时必须分段压（夯）实，人填料时必须分段压（夯）实，人填料时必须分段压（夯）实，人工夯实时，每段填料厚度不应大于工夯实时，每段填料厚度不应大于工夯实时，每段填料厚度不应大于工夯实时，每段填料厚度不应大于400mm400mm。n n 4 4 施工顺序宜由外围或两侧向中间施工顺序宜由外围或两侧向中间施工顺序宜由外围或两侧向中间施工顺序宜由外围或两侧向中间进行。在软土中宜间隔成桩。进行。在软土中宜间隔成桩。进行。在软土中宜间隔成桩。进行。在软土中宜间隔成桩。n n 5 5 桩位偏差桩位偏差桩位偏差桩位偏差(pinch)(pinch)不宜大于不宜大于不
12、宜大于不宜大于0.50.5倍倍倍倍桩身直径。桩身直径。桩身直径。桩身直径。第24页/共50页第二十五页，共50页。1 石灰桩施工检测宜在施工石灰桩施工检测宜在施工后后710d后进行；竣工验收检后进行；竣工验收检测宜在施工后测宜在施工后28d进行。进行。2 施工检测可采用静力触探、施工检测可采用静力触探、动力触探或标准贯入试验动力触探或标准贯入试验(shyn)。检测部位为桩中心及。检测部位为桩中心及桩间土，每两点为一组。检测桩间土，每两点为一组。检测组数不少于总桩数的组数不少于总桩数的1。10.5 10.5 质量检验质量检验10.5 Quality Verification Test第25页/共
13、50页第二十六页，共50页。3 石灰桩地基竣工验收时，石灰桩地基竣工验收时，承载力检验应采用复合地基载承载力检验应采用复合地基载荷试验荷试验(shyn)。数量宜为地。数量宜为地基处理面积每基处理面积每200m2左右布置左右布置一个点，且每一单体工程不应一个点，且每一单体工程不应少于少于3点。点。4 石灰桩复合地基载荷试验石灰桩复合地基载荷试验(shyn)沉降比沉降比s/d取取0.012。第26页/共50页第二十七页，共50页。n n10.1 Introductionn nLime columns,where quicklime is mixed in situ with soft soil,a
14、re common in Sweden and Finland,to stabilize soft clay and silt as well as organic soils.In China,lime column is usually consists of quicklime or mixture of quicklime and flaysh.And flyash can also be replaced by cinder or other materials.第27页/共50页第二十八页，共50页。n nThe method has gradually been improved
15、 and new The method has gradually been improved and new applications have been found.Lime columns have applications have been found.Lime columns have mainly been used to increase the stability and to mainly been used to increase the stability and to reduce the settlements of buildings and road reduc
16、e the settlements of buildings and road embankments and to increase the stability of trenches embankments and to increase the stability of trenches for sewer lines,water mains and heating ducts.The for sewer lines,water mains and heating ducts.The diameter and the length have gradually increased and
17、 diameter and the length have gradually increased and the time required for the installation of the columns the time required for the installation of the columns has been reduced significantly as well as the costs.has been reduced significantly as well as the costs.第28页/共50页第二十九页，共50页。n nLime column
18、s have also been used to stabilize Lime columns have also been used to stabilize organic soils,where unslaked lime alone has not organic soils,where unslaked lime alone has not been effective.Lime columns have the advantage been effective.Lime columns have the advantage that the permeability and the
19、 ductility are normally that the permeability and the ductility are normally high.In addition the ground temperature is high.In addition the ground temperature is increased by the heat generated during the slaking.increased by the heat generated during the slaking.The increase of the shear strength,
20、caused by the The increase of the shear strength,caused by the reduction of the water content,is usually reduction of the water content,is usually significant.significant.第29页/共50页第三十页，共50页。n nSince a large number of factors affect the behavior of lime columns,it is necessary to determine for each s
21、ite the effect of different stabilizers(e.g.lime,cement,gypsum,industrial waste and different ashes)on compressibility,shear strength and permeability of the stabilized soil.Extensive field and laboratory tests are usually required.第30页/共50页第三十一页，共50页。n nThe bearing capacity and the shear resistance
22、 of the columns are to a large extent governed by the axial load and by the confining pressure.第31页/共50页第三十二页，共50页。n n10.2 10.2 PermeabilityPermeabilityn n Since the permeability of the laboratory samples often is different from Since the permeability of the laboratory samples often is different fro
23、m the in situ permeability,where cracks and fissures in the columns affect the the in situ permeability,where cracks and fissures in the columns affect the results,it is desirable to determine the permeability from the measured results,it is desirable to determine the permeability from the measured
24、excess pore water pressures in the columns.The permeability can also be excess pore water pressures in the columns.The permeability can also be determined from the settlement rate of,for example,embankments and determined from the settlement rate of,for example,embankments and fills.fills.第32页/共50页第
25、三十三页，共50页。n nThe difference between the permeability of the The difference between the permeability of the columns and the permeability of laboratory columns and the permeability of laboratory samples has been attributed to cracks and samples has been attributed to cracks and fissures in and around
26、the columns caused by fissures in and around the columns caused by shrinkage.shrinkage.n nThe permeability of lime columns has been The permeability of lime columns has been determined in the laboratory by constant and by determined in the laboratory by constant and by falling head permeability test
27、s as well as by triaxial falling head permeability tests as well as by triaxial and oedometer tests with samples from the columns and oedometer tests with samples from the columns or with small laboratory samples.The permeability or with small laboratory samples.The permeability has been found to de
28、crease with time.has been found to decrease with time.第33页/共50页第三十四页，共50页。n nBaker et al.(1997)report that the in situ Baker et al.(1997)report that the in situ permeability of lime columns can be up to two permeability of lime columns can be up to two orders of magnitude higher than the permeabilit
29、y orders of magnitude higher than the permeability of laboratory-mixed samples.The permeability as of laboratory-mixed samples.The permeability as determined in the field was 5110-9 to 35010-9 m/s determined in the field was 5110-9 to 35010-9 m/s for lime columns.The permeability of the for lime col
30、umns.The permeability of the samples prepared in the laboratory was only 210-9 samples prepared in the laboratory was only 210-9 m/s.The permeability was observed to decrease m/s.The permeability was observed to decrease with increasing curing time and with increasing with increasing curing time and
31、 with increasing confining pressure.The permeability has also confining pressure.The permeability has also been observed to decrease with time and even been observed to decrease with time and even when the confining pressure is low.when the confining pressure is low.第34页/共50页第三十五页，共50页。n n10.3 10.3
32、Behavior of single columnsn nTransfer lengthTransfer lengthn nIt is necessary to transfer the load from the It is necessary to transfer the load from the embankment to the columns or past weak sections in embankment to the columns or past weak sections in the columns.The estimated transfer length is
33、 2d,the columns.The estimated transfer length is 2d,when the load transfer depends entirely on the shaft when the load transfer depends entirely on the shaft resistance.When the dry crust is thin or is poorly resistance.When the dry crust is thin or is poorly developed,the transfer length could be u
34、p to 10d.The developed,the transfer length could be up to 10d.The transfer length decreases with time because of the transfer length decreases with time because of the increase of the shear strength of the soil caused by increase of the shear strength of the soil caused by consolidation.The time req
35、uired for the consolidation consolidation.The time required for the consolidation can be large for lime columns due to the low can be large for lime columns due to the low permeability of the stabilized soil.The transfer length permeability of the stabilized soil.The transfer length can also be larg
36、e at the base of a floating column wall,can also be large at the base of a floating column wall,when the point resistance is low.when the point resistance is low.第35页/共50页第三十六页，共50页。n nThe undrained shear strength and the shaft resistance The undrained shear strength and the shaft resistance for a n
37、ormally consolidated clay(OCR=1.0)increase for a normally consolidated clay(OCR=1.0)increase with increasing effective overburden pressure.with increasing effective overburden pressure.n nThe transfer length,which depends mainly on the The transfer length,which depends mainly on the shear strength o
38、f the soil around the columns,is shear strength of the soil around the columns,is 3.2m(4d)for a 0.8m diameter column at an axial 3.2m(4d)for a 0.8m diameter column at an axial load of 200kN(400 kPa)and a shaft resistance of 25 load of 200kN(400 kPa)and a shaft resistance of 25 kPa,when the point res
39、istance is zero and 4.1 m kPa,when the point resistance is zero and 4.1 m when the point resistance is 144 kPa.when the point resistance is 144 kPa.第36页/共50页第三十七页，共50页。n nLateral displacement of single columnsn nThe columns,which are located below an The columns,which are located below an embankment
40、,could be displaced laterally by the embankment,could be displaced laterally by the high lateral earth pressure in the embankment.high lateral earth pressure in the embankment.However,the lateral displacement of the soft soil However,the lateral displacement of the soft soil and of the columns below
41、 an embankment is and of the columns below an embankment is usually small.A large lateral displacement can usually small.A large lateral displacement can be expected,when the stability of the be expected,when the stability of the embankment is low and the global factor of embankment is low and the g
42、lobal factor of safety is less than about 1.5.The lateral safety is less than about 1.5.The lateral displacement of the columns has been up to 0.5 displacement of the columns has been up to 0.5 m next to a slope or a deep excavation.m next to a slope or a deep excavation.第37页/共50页第三十八页，共50页。n n10.4
43、10.4 Settlement of buildings and of other structuresSettlement of buildings and of other structuresn nSettlement of single columns and of column groupsSettlement of single columns and of column groupsn nThe main purpose of soil stabilization in the 1960s and The main purpose of soil stabilization in
44、 the 1960s and 1970s was to reduce the settlements and the angular 1970s was to reduce the settlements and the angular rotation of relatively light buildings.The bearing rotation of relatively light buildings.The bearing capacity of the unstabilized soil without the columns capacity of the unstabili
45、zed soil without the columns was often sufficient to support up to two-storey was often sufficient to support up to two-storey buildings without basement when the clay is normally buildings without basement when the clay is normally consolidated or is slightly overconsolidated.consolidated or is sli
46、ghtly overconsolidated.第38页/共50页第三十九页，共50页。n nMost buildings can accommodate relatively large settlements,0.2 to 0.3 m or more,without structural damage provided the differential settlements are not excessive.Embankments can in general accommodate a much larger settlement than buildings,provided the
47、 settlements are uniform.n nThe length and the spacing of the columns can be varied to take advantage of the increase of the compression modulus and of the undrained shear strength with depth.第39页/共50页第四十页，共50页。n nThe settlement of embankments and structures,which are The settlement of embankments a
48、nd structures,which are supported by single columns or by column groups,is supported by single columns or by column groups,is usually checked by assuming that the axial deformations of usually checked by assuming that the axial deformations of the columns are the same as the deformations of the the
49、columns are the same as the deformations of the unstabilized soil between the columns.The settlement of a unstabilized soil between the columns.The settlement of a column group is governed by the weighted average column group is governed by the weighted average compression modulus of the columns and
50、 of the compression modulus of the columns and of the unstabilized soil between the columns when the shear unstabilized soil between the columns when the shear strength of the column is low.Test results indicate that the strength of the column is low.Test results indicate that the behaviour of the s