CSA Seminar 2- Piling Work

1、桩基础简介桩基础简介CSA Seminar 2: Piling Work工程桩基础工程桩基础 Piling Work第第1节节 概述概述 Section 1: General Introduction第第2节节 桩的分类桩的分类Section 2 Type of Piles第第3节节 典型施工工艺典型施工工艺Section 3 Typical Piling Construction 第第4节节 各种桩的经济技术比较各种桩的经济技术比较Section 4 Cost Comparison of Different Piles第第5节节 特殊案例特殊案例Section 5 Typical Cases

2、第第1 1节节 概概 述述 Section 1 Brief Introduction 如果建筑场地浅层的土质不能满足建筑物对如果建筑场地浅层的土质不能满足建筑物对地基承地基承载力载力和和变形变形的要求、而又不宜采取的要求、而又不宜采取地基处理措施地基处理措施时，就需时，就需要考虑以下部坚实土层或岩层作为持力层的要考虑以下部坚实土层或岩层作为持力层的深基础深基础方案。方案。桩基础桩基础是应用最为广泛的一类深基础是应用最为广泛的一类深基础。In case that the bearing capacity and settle tolerance cannot be met, and the so

3、il cannot be improved with some measures e.g. injection of cement mortar, etc., the piled foundation will be applied. 桩基础：基桩桩基础：基桩+ +承台。承台。Piled Foundation: Piles +Pile Cap桩基础设计须满足桩基础设计须满足地基承载力地基承载力和和变形变形这两项基本要求。这两项基本要求。 Basic requirements for pile design: Bearing capacity and settlement tolerance 承

4、台 Pile Cap桩 Pile地基变形性验算： 附加应力验算Model for Settlement CalculationAdditional StressCompensation from SoilGround LevelGround LevelAdditional Stress第第2节节 桩的分类桩的分类 Section 2: Type of Pile一、按桩的使用功能分类一、按桩的使用功能分类 Based on load : 1.竖向抗压桩竖向抗压桩 Anti-pressure pile 2.2.竖向抗拔桩竖向抗拔桩 Anti-pull pile God says it is a a

5、nti-pull pile.Cases of Anti-pull PileSoil FrictionPiles to PitU/G Water LevelSoil FrictionWind LoadPile to Column Foundation二、按桩承载性能分类二、按桩承载性能分类 Based on bearing type: 1.摩擦桩摩擦桩 Friction Bearing Pile (a) 2.端承桩端承桩 End bearing Pile (d) 3.摩擦端承桩摩擦端承桩 End bearing Pile with Friction (c) 4.端承摩擦桩端承摩擦桩 Fricti

6、on Bearing Pile with End bearing(d) 四种桩型图示：四种桩型图示：Sketches for the Four Types of Pile:三、三、按桩身材料分类按桩身材料分类 Based on material可分为可分为木桩木桩，混凝土桩混凝土桩，钢桩钢桩，组合桩组合桩等。等。Wood pile, RC pile, Steel pile, etc.四、按设置效应分类四、按设置效应分类 Based on impaction on soil 1.非挤土桩非挤土桩 Non-soil-push pile挖孔桩，钻孔桩挖孔桩，钻孔桩 （包括成孔灌注桩）（包括成孔灌注桩

7、）Bored pile, drilled pile (including CFA),环境影响，渣土，泥浆污染环境影响，渣土，泥浆污染Environment impact, soil and slurry.2.2.挤土桩挤土桩 Soil Push Pile 静压桩静压桩 Hydraulic Piling 锤击桩锤击桩 Diesel Hammer Piling五、按桩径大小分类五、按桩径大小分类 Based on size 1.小桩小桩 Small size 桩径桩径d250mm。小桩多用于基础加固（树根桩或锚杆。小桩多用于基础加固（树根桩或锚杆静压桩静压桩)。 d250mm， use for r

8、einforcing existing foundation 2.中等直径桩中等直径桩 Middle size 250mmd800mm, used for all kinds of common construction 3.3.大直径桩大直径桩 Big size d800mm, for extremely heavy construction e.g. big tanks foundation of LNG, petrol- chemicals.六、按施工工艺分类六、按施工工艺分类 Based on Construction Methodv预制桩：预制桩：根据沉入土中的方法，可分根据沉入土中

9、的方法，可分锤击桩锤击桩、静静力压桩力压桩、振动沉桩振动沉桩和和水冲沉桩水冲沉桩等；等；Precast piling: diesel hammer, hydraulic, etc.v灌注桩：灌注桩：Cast-on-site.Bored, dry drilled, CFA, etc. 预制桩与灌注桩的优劣比较预制桩与灌注桩的优劣比较Comparison between Pre-casted and Cast-on-site. 第第3 3节节 桩典型的施工工艺桩典型的施工工艺Typical Piling Process v预制桩的施工工艺预制桩的施工工艺 Pre-casted pile const

10、ruction 1. 预制桩的种类预制桩的种类 Types of Pilea.钢筋混凝土预制方桩钢筋混凝土预制方桩 RC Square Pile b. Pre-stessTube Pilec.预应力空心方桩Pre-stressed Hollow Square Pile2. 2. 锤击法施工锤击法施工 Diesel Hammer Piling 2.1 Piling RigPicture SketchThe video of diesel hammer piling:The flash of how diesel hammer works:3. 3. 静力压桩静力压桩 Hydraulic Rig

11、Sketch of Rig1. Top beam2. Pressure meter3. Piling cap4. Pile5. Weight cell6. Bottom plate7. Rail 8. Pile connection 9. Pile11. Bottom late12. Windlass13. Sling14. Guide Cage Picture of Rigv灌注桩的施工工艺灌注桩的施工工艺 Cast-on-site Pile1 1 干作业钻孔灌注桩干作业钻孔灌注桩 Dry Drill (a) Drilling (b) Rebar Cage (c) Concrete Pour

12、ing 2 2 泥浆护壁成孔灌注桩泥浆护壁成孔灌注桩 CFACFA Drilling and Slurry TransferrringConcrete Pouring造价：灌注桩预应力方桩预应力管庄实心方桩锤击桩静压桩Cost: CFAPre-stress RC Hollow SquarePre-stress RC TubeRC SquareDiesel Hammer Hydraulic同直径承载能力：灌注桩预应力管桩预应力方桩实心方桩Bearing Capacity:CFAPre-stress RC TubeRC Square Pre-stress RC Hollow Square第第4 4

13、节节 桩经济技术比较桩经济技术比较Section 4 Cost and Bearing Capacity5.1 美丽的楼房为何就倒了呢？How does the nice building collapse?第第5节节 特殊案例特殊案例 Special Cases5.1.1动画演示Flash for the Accident5.1.2 事故分析 Accident Analysis 在基础一侧大开挖不作任何防护，造成两侧土压力不平衡 No sheeting or shoring to the pit.把开挖的土方在另一侧堆放，加剧了土压力的不平衡 Excavated soil piled nex

14、t to the building.雨水使土壤含水率增加，使土体的抗剪能力下降，使土体发生侧移 Rain water made the soil full of water and reduce its anti-shear capacity.土体侧移产生的剪力，和土侧压力产生的弯矩 Moving soil caused the shear affect to the pile. Pressure of the piled soil caused movement affect to the building.预应力管桩本身抗剪抗弯的性能极差 The PC is not supposed to bear shear load.管桩被剪断，建筑产生偏心。在无桩约束的情况下，楼体迅速倾覆。The piles were sheared and broken and the building became eccentric. Without pile reinforced, the building collapse quickly subjected to the eccentric gravity. 5.2 阿克苏项目 Cases in AN ProjectsEA ( Square Hollow VS PHC Tube)PA ( Mis