标准编号:	DBJ/T 15-94-2013
中文名称:	静压预制混凝土桩基础技术规程
英文名称:	Specification for static pressing precasted concrete pile foundation
行业分类:	DB    地方标准
发布日期:	2013-05-08
实施日期:	2013-10-1
标准状态:	现行
翻译语言:	英文
文件格式:	PDF
中文字符数:	120000 字
翻译价格(元):	12000.00 元
交付时间:	付款后 1 个工作日

Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative.



For this standard, the project is approved in accordance with the document YUEJIANHAN [1993] No. 265 “Notice on issuing the task of developing Specification for static pressing precasted concrete pile foundation” issued by the former Guangdong Construction Committee. Previously, the static pressing precast concrete piles used in Guangdong were precasted reinforced concrete square-piles with side length less than 400mm; at the end of 1994, the technical difficulties in the construction of prestressed tube-piles by static pressing method were overcome. In the following years, the application of static pressing precast concrete tube-piles has developed rapidly in Guangdong Province and even the whole country, and great progress has also been made in the aspect of manufacturing technology of hold type hydraulic pressing pile machine. In June 1998, the preparation of this Specification was officially started, and the name of the specification was Specification for static pressing precasted concrete pile foundation; the discussion draft was completed in 2001, and the exposure draft was basically completed in 2003. However, in order to coordinate with the revision of the standard of Guangdong DBJ/T 15-22 Specification for driven prestressed concrete tube-pile foundation and the national standard GB 13476 Pretensioned spun concrete piles, the compilation speed was slowed down, during which period modification has been carried out for several times. The edition of this Specification is mainly in charge of the Civil engineering and Architectural Society of Guangdong, participated by 20 units including schools, manufacturers of static pressing precast concrete pile and pressing pile machine, and those for survey, design, construction, supervision, quality inspection, scientific research.



There are 6 clauses and 6 annexes in this Specification, with the main technical contents as follows: general provisions; terms and symbols; geotechnical engineering investigation of static pressing precast concrete pile foundation; design of static pressing precast concrete pile foundation; construction of static pressing precast concrete pile; and engineering quality inspection and acceptance of works.





Specification for static pressing precasted concrete pile foundation



1 General provisions



1.0.1 This specification is developed with a view to implementing the national technical and economic policies, so that the design and construction of static pressing precast concrete pile foundation in Guangdong Province meet the requirements of safety and application, technological advance, economic rationality, quality assurance, and environmental protection.



1.0.2 This Specification is developed in accordance with the current relevant standards of the nation and Guangdong Province, on the basis of summarizing the existing experience in Guangdong and taking into account the particularity of the design and construction of the foundation of static pressing precast concrete pile.



1.0.3 This Specification is applicable to geotechnical engineering investigation, design, construction, quality inspection, testing and project acceptance of static pressing precast concrete pile foundation with low pile caps of buildings (structures) constructed by static pile pressing machine. Other contents not specified in this Specification shall comply with the current relevant standards of the nation and Guangdong Province.



1.0.4 Static pressing precast concrete pile may be pre-tensioned pre-stressed concrete tube-pile (hereinafter referred to as static pressing precast concrete tube-pile) and prefabricated reinforced concrete square-pile (hereinafter referred to as static pressing precast concrete square-pile).



1.0.5 Static pressing precast concrete pile is applicable to non-seismic areas and areas with seismic fortification intensity of 6 and 7 and those with seismic fortification intensity of 8 in which category of building sites is I or II, with the mechanical indexes of the selected pile type meeting the design requirements and relevant standards.



1.0.6 The construction provisions in this Specification are compiled based on the performance and construction technology of the hold type hydraulic pressing pile machine. When using other types of pile pressing machine or pile pressing construction method, attention shall be paid to the particularity of their respective construction technologies.



1.0.7 Static pressing precast concrete pile foundation should be used for rock stratum with covering stratum easy to be pressed through and pile tip bearing stratum intensely or completely weathered; hard plastic~hard cohesive soil layer; medium-dense~dense gravelly (cobbly) soil, sandy soil and silt layers.



Unless effective measures have been taken, the static pressing precast concrete pile foundation should not be adopted for the following geological conditions:



1 Untreated sites with soft topsoil and ground bearing capacity characteristic value ≤120kPa;



2 There are many spherical weathered bodies (boulder) or other obstacles in the covering stratum;



3 The pile tip bearing stratum is medium-dense~dense sand layer and its covering stratum is almost all slightly-dense~medium-dense sand layer.



4 The covering stratum contains a hard included thin layer which is difficult to press through;



5 Karst stratum with large fluctuation of bedrock surface and no suitable bearing stratum on it;



6 Non-karst areas, with covering stratum being soft soil layer such as sludge and moderately weathered or slightly weathered rock layer directly under the covering stratum;



7 The pile tip bearing stratum is weathered rock stratum which is easy to soften after disturbance.



8 Sites with seismic fortification intensity of 8 and construction sites of Category III or IV;



9 Sites with ground water or foundation soil strongly corrosive to pile shaft concrete, steel bars and steel parts.



1.0.8 Static pressing precast concrete pile foundation is a kind of pile foundation project that can be successfully completed only by close cooperation between investigation, design and construction. Especially in the construction stage, investigation, design and construction technicians shall cooperate closely. When the actual pile length is much shorter than the design pile length, they shall study together and make necessary adjustments to the bearing capacity and number of piles in time.

 

2 Terms and symbols



2.1 Terms



2.1.1



method of static pressing of pile



construction method of pressing precast pile into the foundation soil (rock) layer with pile pressing machine by certain depth, which is called static pressing method for short



2.1.2



static pressing precast concrete pile



precast reinforced concrete pile constructed by static pressing method



2.1.3



static pressing precast concrete square-pile



precast reinforced concrete square-pile constructed by static pressing method



2.1.4



static pressing precast concrete tube-pile



pretensioned pre-stressed concrete tube-pile constructed by static pressing method



2.1.5



foundation of static pressing precast concrete pile



foundation of building (structure), which is composed of static pressing precast concrete pile and pile cap connected to the top of pile, which is called foundation of static pressing pile for short



2.1.6



slenderness ratio



ratio of pile length to diameter for static pressing precast concrete tube-pile or that of pile length to side length of static pressing precast concrete square-pile



2.1.7



hydraulic pressing pile machine



static pressing precast concrete pile construction machine which applies pressure to the pile shaft through a hydraulic force transmission mechanism



2.1.8



jack type hydraulic pressing pile machine



hydraulic pressing pile machine with pile pressing force acting on the top face of pile



2.1.9



hold type hydraulic pressing pile machine



hydraulic pressing pile machine applying pressure downward with the clamping device holding the pile shaft



2.1.10



clamping device



hydraulic component of a pile pressing machine which uses a plurality of hydraulic clamping blocks to hold the pile shaft from the side and may move up and down along the guide frame



2.1.11



device of pressing border pile



set of special pile-holding and pile-pressing mechanism which is installed on the side of pile pressing machine and is used for pressing border piles



2.1.12



additional weight



detachable weight block attached to the pile frame for adjusting the weight of the pile pressing machine



 

2.1.13



minimum distance for border pile



minimum distance from the center of the pile that can be pressed when the pile pressing machine is adjacent to an existing building (structure) to the edge of such building (structure)



2.1.14



pressure intensity of ground contact



average pressure value per unit area of the grounding part during traveling or construction of the pile pressing machine



2.1.15



method of repeated pressing



operation method of applying pressure again after a period of time after the final pressure of static pressing precast concrete pile construction



2.1.16



allowable pressure of clamping pile shaft



maximum pile pressing force allowed by the pile shaft when the pile shaft is held and pressed by hold type pile pressing machine



2.1.17



control standard of final pressing



control measures and conditions for termination of pile pressing construction determined to meet the design requirements of static pressing precast concrete pile



2.1.18



final pressure value



final pile pressing force applied when the control standard of final pressing is reached and thus the pile pressing is terminated



 

2.1.19



times of continuously repeated pressing with final pressure



number of times that the static pressing precast concrete pile is continuously pressed with final pressure value in an intermittent way when the static pressing precast concrete pile is finally pressed



2.1.20



time of steady pressure



time of applying pressure continuously with the final pressure value at the time of final pressing



2.1.21



ultimate vertical compression bearing capacity of a single pile



maximum load borne by a single pile under the vertical load before it reaches the failure state or when it is deformed and is no longer suitable for bearing



2.1.22



ratio of ultimate vertical bearing capacity and final pressure value



ratio of ultimate vertical compression bearing capacity of a single pile to final pressure value for construction of static pressing precast concrete pile



2.1.23



method of pressing pile with pre-augering



operation method of pre-hole-forming at the pile location with pilot hole equipment, then placing the precasted pile into the hole and applying pressure with a pile pressing machine



2.1.24



pile loading



construction process of lifting static pressing precast concrete pile into the clamping device of pile pressing machine



2.1.25



characteristic value of the vertical bearing capacity of a single pile



bearing capacity value obtained by dividing the maximum load borne by a single pile under the vertical load (pressure or uplift) before it reaches the failure state or when it is deformed and is no longer suitable for bearing by the safety factor



2.1.26



machine floating



state with part of the chassis of the pile pressing machine lifting off the ground and becoming suspended during the pile pressing process



2.2 Symbols



2.2.1 Resistance and material performance



Ec——the elastic modulus of pile shaft concrete of static pressing precast concrete pile;



fc——the design value of the axial compressive strength of concrete;



fnk——the standard value of bond strength between core concrete and inner wall of tube-pile;



Fptk——the standard value of tensile strength of pre-stressed steel bar of tube-pile;



fy——the design tensile strength of steel bar;



qsia——the characteristic value of lateral resistance of the ith layer soil (rock) of single pile;



qpa——the characteristic value of tip resistance of a single pile;



qc——the cone head resistance of static cone penetration;



Ra——the characteristic value of singe pile vertical compression bearing capacity;



Rha——the characteristic value of singe pile horizontal bearing capacity;



Rta——the characteristic value of singe pile vertical uplift bearing capacity;



Rm——the design value of bending bearing capacity of pile shaft;



Rp——the design value of vertical bearing capacity of pile shaft of static pressing precast concrete pile;



σpc——the effective compressive pre-stress value of pre-stressed tube-pile concrete;



Pjmax——the allowable pressure of clamping pile shaft.



2.2.2 Actions and effects



Fk——the vertical forces acting on the top of pile cap in the standard combination of load effects;



Gk——the standard value of dead weight of pile cap and the soil thereon;



Gp——the dead weight of static pressing precast concrete pile;



Hk——the horizontal force acting on the bottom of pile cap in the standard combination of load effects;



Hik——the horizontal force acting on the top of any pile in the standard combination of load effects;



Mxk——the bending moment acting on the bottom of pile cap through the x axis of pile group centroid in the standard combination of load effects;



Myk——the bending moment acting on the bottom of pile cap through the y axis of pile group centroid in the standard combination of load effects;



M——the design value of bending moment of single pile in the basic combination of load effects;



N——the measured standard penetration number;



N′——the corrected standard penetration number;



Nk——the standard value of measured standard penetration number of layer;



Pze——the final pressure value of construction of static pressing precast concrete pile;



Qk——the vertical force of any pile under the axial vertical force in the standard combination of load effects;



Qik——the vertical force of the ith pile under the eccentric vertical force in the standard combination of load effects;



Qt——the design value of single pile vertical uplift force in the basic combination of load effects;



Qtk——the vertical uplift force acting on the top of a single pile in the standard combination of load effects;



Ymax——the maximum pile pressing force of hydraulic pressing pile machine.



2.2.3 Geometric parameters



A——the sectional area of static pressing precast concrete pile;



Aa——the nominal sectional area of a single pre-stressed steel bar of tube-pile;



Ap——the horizontal projection area of static pressing precast concrete pile tip;



b——the side length of static pressing precast concrete square-pile;



d——the outside diameter of static pressing precast concrete tube-pile;



d1——the inside diameter of static pressing precast concrete tube-pile;



h——the buried depth of static pressing precast concrete pile;



hb——the depth of static pressing precast concrete pile tip into the bearing stratum;



L——the length of single section of pile; the buried depth of static pressing precast concrete pile;



I——the cross sectional inertia moment of static pressing precast concrete pile;



La——the depth of core concrete on the top of pile;



li——the thickness by which the static pressing precast concrete pile passes through the ith layer of soil (rock);



Up——the outer perimeter of pile shaft of static pressing precast concrete pile.



2.2.4 Calculation coefficients



α——the length correction coefficient of penetration rod used in standard penetration test; the recovery coefficient of soil; the horizontal deformation coefficient of static pressing precast concrete pile;



β——the ratio of ultimate vertical bearing capacity and final pressure value;



λi——the reduction coefficient of anti-uplift frictional resistance;



ξp——the correction coefficient of resistance at static pressing precast concrete pile tip;



ψc——the pile formation technological coefficient.



3 Geotechnical engineering investigation of static pressing precast concrete pile foundation



3.0.1 For the geotechnical engineering investigation point of foundation of static pressing pile, the plane layout, depth and sampling and testing requirements of each main soil layer within the exploration depth shall meet those specified in the current national standard GB 50021 Code for investigation of geotechnical engineering and JGJ 72 Specification for geotechnical investigation of tall buildings as well as the following:



1 The spacing of exploration points should be 12m~24m, and there should be no less than 5 exploration holes in each unit project, in which the number of control exploration holes shall not be less than 1/2 of the total number of exploration holes and not less than 2. If the geological conditions are complex, the number of exploration holes shall be properly added.



2 The depth of general exploration hole shall be enough to reach 3 m ~ 5 m below the estimated pile tip bearing stratum; the depth of the control exploration hole shall be enough to reach 5 m ~ 10 m below the estimated pile tip bearing stratum;



3 The topsoil of the construction site shall be investigated in detail. For the investigation, portable dynamic sounding, soil sampling, standard penetration test and other means shall be adopted to accurately find out the bearing capacity of 3m thick soil layer on the surface.



3.0.2 If the static pressing precast concrete pile is selected as the foundation in the design, in-situ tests such as standard penetration test, heavy cone dynamic sounding test and double bridge probe static sounding test shall be appropriately added according to the characteristics of geotechnical layer in the geotechnical engineering investigation.



 

3.0.3 The following requirements shall be met if standard penetration test is carried out:



1 Within the depth range of the control exploration hole, each soil layer and completely weathered and strongly weathered rock stratum shall be subject to standard penetration test. The standard penetration test shall be carried out once each layer in sludge and muddy soil layer, once every 2m in thickness in hard plastic~hard clay layer, residual soil layer and completely weathered rock layer, once every 1m in thickness in medium-dense ~ dense sand layer, and once every 1m in thickness in soil (rock) layer to be used as the pile tip bearing stratum;



2 For the general exploration hole in the layer to be used as pile tip bearing stratum, the standard penetration test shall be carried out once every 1m in thickness;



3 If the standard penetration test is conducted in the soil (rock) layer to be used as the pile tip bearing stratum, and the number of blow count has reached 100 and the penetration depth is less than 30cm, the test may be terminated, with the actual penetration depth at 100 blow counts recorded, but the drilling depth shall still meet those specified in 3.0.1.



3.0.4 If double bridge probe static sounding test is adopted, those specified in national standard GB 50021 Code for Investigation of Geotechnical Engineering shall be met, and the hole shall reach the depth about 5m for the rock-soil layer with tip resistance qc≥20MPa or the hole shall be drilled until the static penetration force ≥300kN. 3.0.5 If the empirical values of pile side friction characteristic value and tip resistance characteristic value in completely and strongly weathered rock stratum are selected, the standard penetration number corrected according to the length of drill stem shall be adopted. The corrected standard penetration number N' shall be calculated using the following equation:



N′＝αN (3.0.5)



where,



N′——the corrected standard penetration number;



N——the measured standard penetration number;



α——the correction coefficient of drill stem length, which may be adopted according to Table 3.0.5.



 

Table 3.0.5 Correction coefficient of drill stem length

Stem length (m) ≤3 6 9 12 15 18 21

Correction coefficient α 1.00 0.92 0.86 0.81 0.77 0.73 0.70

Stem length (m) 24 27 30 33 36 39 ≥42

Correction coefficient α 0.67 0.64 0.61 0.58 0.55 0.52 0.49



3.0.6 Completely and strongly weathered granite rocks and residual soils may be classified according to the measured standard penetration number N, N≥50 means the rock is strongly weathered, 50>N≥30 means the rock is completely weathered, and N<30 means the rock is weathered into residual soil. Reference may be made to this for the classification of completely weathered and strongly weathered rocks of other types. When estimating the depth of pile pressing, the corrected standard penetration number N′ shall be adopted.



3.0.7 In geotechnical engineering investigation, the corrosivity of water and soil in the project site to precast piles shall be evaluated; when there is enough experience or sufficient data to determine that the water or soil in the project site is not corrosive to building materials, it is not necessary to take samples to test the corrosivity index; otherwise, water samples or soil samples shall be taken for testing. Sampling methods of water samples and soil samples, testing of corrosivity indexes of water and soil, and evaluation of corrosivity shall be carried out in accordance with those specified in the national standard GB 50021 Code for investigation of geotechnical engineering.



3.0.8 The geotechnical engineering investigation report of foundation of static pressing pile shall meet those specified in the national standard GB 50021 Code for investigation of geotechnical engineering, and should list the following contents:



1 Project overview, site location, topography and geomorphology, names and characteristics of various rock and soil layers, as well as geological age of geomorphic units and main rock and soil layers and analysis and demonstration of the causes thereof;



2 There shall be a clear judgment conclusion on the distribution and origin of bad geological phenomena in the construction site, such as boulder, hard interlayer, karst, soil cave, and structural fracture, and on the influence of rock slope on the stability of pile tip;



3 Ground water type, stable water level and its variation range;



4 The conclusion of evaluating the corrosivity of ground water and foundation soil in the site to the precast concrete piles;



5 Liquefiable stratum distribution and judgment data provided according to seismic intensity in seismic fortification area;



6 Test results of standard penetration test and other in-situ tests;



7 The evaluation of the possibility of sinking machine in static pressing precast concrete pile construction made according to the bearing capacity of soil layer within 3m depth of topsoil;



8 Suggestions proposed for selecting pile tip bearing stratum and for pile sinking feasibility;



9 Put forward the side friction characteristic value and tip resistance characteristic value in accordance with the foundation of static pressing pile; estimate the characteristic value of the vertical bearing capacity of a single pile and its deformation characteristics;



10 Assess the weathered rock layers on the site that are easy to soften after disturbance, and put forward countermeasures;



11 Evaluate the impact of pile pressing on the surrounding environment;



12 The plan layout of exploration points, engineering geological histogram, engineering geological profile, and contour map of rock and soil layers such as strongly weathered rock which are capable of being used as pile tip bearing stratum and color photo of rock core.



4 Design of foundation of static pressing pile



4.1 General requirements



4.1.1 According to the building scale, functional characteristics, adaptability to differential deformation, complexity of site foundation and building (structure) shape, and the degree of damage or influence on normal use of building (structure) caused by pile foundation problems, the design of foundation of static pressing pile shall be classified into three design grades listed in Table 4.1.1. When designing the foundation of static pressing pile, the design grade shall be determined according to Table 4.1.1.



 

Table 4.1.1 Design grade of foundation of static pressing pile

Design grade Building type

Grade A (1) Important industrial and civil buildings;

(2) High-rise buildings with more than 30 storeys or with height more than 100m;

(3) Buildings with complex shapes formed by high building and low building connected to each other with the high one 10 storeys more than the low one;

(4) Buildings (structures) with special requirements for foundation deformation;

(5) General buildings with more than 7 storeys and complex site and foundation conditions, and buildings located at sloped land and shoreside.

(6) Newly built buildings (structures) which have great influence on the existing works;

(7) Large-span (≥60m) structural buildings;

(8) Large-area multi-storey underground buildings (structures).

Grade B Buildings (structures) other than those of Grades A and C

Grade C General buildings with 7 storeys or less and with simple site and foundation conditions and uniform load distribution, and minor light buildings (structures)



4.1.2 For the design of foundation of static pressing pile, the following basic data shall be made available:



1 Geotechnical engineering investigation report meeting those specified in clause 3 of this Specification;



2 Construction site and environmental conditions, including the distribution of high-voltage overhead lines, underground pipelines and underground structures; the safety level, subgrade and foundation conditions of adjacent buildings (structures) that may be affected by pile pressing; and the entry and exit and field operation conditions of pile pressing machine;



3 Types and forms of superstructure of buildings (structures); load size, distribution and nature; requirements of production technology and equipment on foundation settlement and horizontal displacement;



4 The general plan of the construction site, and the plan of the basement or the first floor structure of the buildings (structures);



5 Relevant data on seismic fortification;



6 Specifications and models, length of single section of pile, joint form and supply conditions of optional static pressing precast concrete pile;



7 Pile pressing equipment performance and its adaptability to geological conditions, as well as capability of pressing border pile.



4.1.3 For foundation of static pressing pile, the following calculations and checking shall be carried out according to specific conditions:



1 The vertical bearing capacity and horizontal bearing capacity of pile foundation shall be calculated respectively according to the use function and stress characteristics of foundation of static pressing pile;



2 The bearing capacity of pile shaft and pile cap structure shall be calculated; and the pile shaft bearing capacity shall also be checked according to the stress conditions during hoisting, transport and pile loading operations;



3 If there is a soft substratum below the pile tip plane, the bearing capacity of the substratum shall be checked;



4 For foundations of static pressing pile located at sloped land and shoreside, the overall stability shall be checked; for foundations of static pressing pile located in area with a large area of silt and muddy soil, when the foundation pit is excavated and there is a pile load around the foundation pit, the overall stability shall be checked, and the relevant prevention measures shall be taken;



5 For foundation of anti-uplift static pressing pile, the anti-uplift bearing capacity of single pile and pile group shall be calculated;



6 For foundations of static pressing pile within seismic fortification area, the seismic bearing capacity shall be checked;



7 For foundations of static pressing pile with design grade of Grade A and with Quaternary soil layer or completely weathered rock layer as the pile tip bearing stratum or those with design grade of Grade B, with complex shape and obviously uneven load distribution or soft soil layer below the pile tip plane, settlement calculation shall be carried out;



8 For foundations of static pressing pile bearing large horizontal load or having strict restrictions on horizontal displacement, the horizontal displacement shall be checked;



9 When the service conditions require to limit the concrete cracks, it is necessary to check the crack resistance or crack width of the foundations of static pressing pile.

Foreword ii
1 General provisions
2 Terms and symbols
2.1 Terms
2.2 Symbols
3 Geotechnical engineering investigation of static pressing precast concrete pile foundation
4 Design of foundation of static pressing pile
4.1 General requirements
4.2 Type, connection and selection of piles
4.3 Pile foundation calculation
5 Construction of static pressing precast concrete pile foundation
5.1 General rules
5.2 Pile pressing equipment
5.3 Lifting and stacking of piles
5.4 Pile pressing
6 Engineering quality inspection and acceptance of works
6.1 Inspection and testing of pile shaft and pile tip before pile pressing
6.2 Engineering quality inspection and testing in the course of pile pressing
6.3 Pile quality inspection and testing after pressing pile
6.4 Acceptance of works
Annex A Requirements for structure and quality of static pressing precast concrete piles
Annex B Structure diagram of commonly-used static pressing precast concrete tube-pile tip
Annex C Schematic diagram for structure of hold type hydraulic pressing pile machine
Annex D Basic parameters table for pile pressing machine
Annex E Reference for static pressing pile machine selection
Annex F Construction record sheet of static pressing pile
Explanation of wording in this specification

1 总则
1.0.1 为了贯彻执行国家的技术经济政策，使广东省静压预制混凝土桩(以下简称静压桩)基础设计与施工做到安全适用、技术先进、经济合理、保证质量、保护环境，制定本规程。
1.0.2 本规程是根据国家及广东省现行有关标准，考虑到静压桩基础设计和施工的特殊性，在总结广东地区已有经验的基础上制订的。
1.0.3 本规程适用于用静力压桩机施工的建(构)筑物低承台静压桩基础的岩土工程勘察、设计、施工及质量检查、检测和工程验收。本规程未作规定的其他内容，尚应按国家和广东省现行有关标准执行。
1.0.4 静压桩可采用先张法预应力混凝土管桩(以下简称静压管桩)和预制钢筋混凝土方桩(以下简称静压方桩)。
1.0.5 静压桩适用于非抗震和抗震设防烈度为6度、7度及建筑场地类别为Ⅰ、Ⅱ类的8度地区，其所选桩型的各项力学指标应满足设计要求和有关标准的规定。
1.0.6 本规程中的施工条文是根据抱压式液压压桩机的性能和施工工艺编制的，在使用其他型式的压桩机或压桩施工法时，则应注意各自施工工艺的特殊性。
1.0.7 静压桩基础宜用于：覆盖层易压穿、桩端持力层为强风化、全风化岩层；硬塑～坚硬的黏性土层；中密～密实的碎(卵)石土、砂土、粉土层的地质条件。
下列地质条件不宜采用静压桩基础或应采取有效措施后方可采用：
1 现场地表土层松软且地面承载力特征值≤120kPa又未经处理的场地；
2 覆盖层中含有较多球状风化体(孤石)或其他障碍物；
3 桩端持力层为中密～密实的砂土层且其覆盖层几乎全是稍密～中密的砂土层；
4 覆盖层中含有难以压穿的坚硬夹薄层；
5 基岩面起伏较大且其上没有合适持力层的岩溶地层；
6 非岩溶地区覆盖层为淤泥等松软土层且其下直接为中风化岩层或微风化岩层；
7 桩端持力层为扰动后易软化的风化岩层；
8 抗震设防烈度为8度且建筑场地类别为Ⅲ、Ⅳ类的场地；
9 地下水或地基土对桩身混凝土、钢筋及钢零部件有强腐蚀作用的场地。
1.0.8 静压桩基础是一种勘察、设计和施工必须密切配合才能顺利完成的桩基础工程，特别是在施工阶段，勘察、设计和施工技术人员应紧密合作，当桩的实际桩长短于设计桩长较多时，应共同研究，及时对桩的承载力和桩数作出必要的调整。
2 术语和符号
2.1 术语
2.1.1 静力压桩法 Method of static pressing of pile
利用压桩机把预制桩压入地基土(岩)层一定深度的施工方法，简称静压法。
2.1.2 静压桩 Static pressing precast concrete pile
用静压法施工的预制钢筋混凝土桩。
2.1.3 静压方桩 Static pressing precast concrete square-pile
用静压法施工的预制钢筋混凝土方桩。
2.1.4 静压管桩 Static pressing precast concrete tube-pile
用静压法施工的先张法预应力混凝土管桩。
2.1.5 静压预制混凝土桩基础 Foundation of static pressing pile
由静压预制混凝土桩和连接于桩顶的承台共同组成的建(构)筑物基础，简称静压桩基础。
2.1.6 长径比 Slenderness ratio
静压管桩的桩长与直径之比或静压方桩的桩长与边长之比。
2.1.7 液压式压桩机 Hydraulic pressing pile machine
通过液压传力机构施加压力于桩身上的一种静压桩施工机械。
2.1.8 顶压式液压压桩机 Jack type hydraulic pressing pile machine
压桩力作用在桩顶端面的液压式压桩机。
2.1.9 抱压式液压压桩机 Hold type hydraulic pressing pile machine
通过夹持机构抱住桩身向下施压的液压式压桩机。
2.1.10 夹持机构 Clamping device
利用多个液压夹块从侧面将桩身抱住并可沿导向架上下移动的压桩机液压部件。
2.1.11 压边桩机构 Device of pressing border pile
装置在压桩机侧边的用于施压边桩的一套特殊的能较方便安装拆卸的抱桩和压桩机构。
2.1.12 配重 Additional weight
附加在桩架上可拆卸的用于调节压桩机重量的定型重物块。
2.1.13 最小边桩距 Minimum distance for border pile
压桩机邻近已有建(构)筑物时所能施压的桩中心到该建(构)筑物边缘的最小距离。
2.1.14 接地压强 Pressure intensity of ground contact
压桩机行走或施工时接地部位的平均单位面积压力值。
2.1.15 复压 Method of repeated pressing
静压桩施工终压后，经间隔一段时间再次施压的作业法。
2.1.16 桩身抱压允许压桩力 Allowable pressure of clamping pile shaft
用抱压式压桩机抱住桩身施压时桩身允许的最大压桩力。
2.1.17 终压标准 Control standard of final pressing
为满足静压桩设计要求而确定的终止压桩施工的控制措施和条件。
2.1.18 终压力值 Final pressure value
达到终压标准而终止压桩的最终压桩力。
2.1.19 终压次数 Times of continuously repeated pressing with final pressure
静压桩终压时用终压力值对静压桩连续间断施压的次数。
2.1.20 稳压时间 Time of steady pressure
终压时每次用终压力值持续施压的时间。
2.1.21 单桩竖向抗压极限承载力 Ultimate vertical compression bearing capacity of a single pile
单桩在竖向荷载作用下到达破坏状态前或出现不适于继续承载的变形时所对应的最大荷载。
2.1.22 竖向抗压极限承载力与终压力相关系数 Ratio of ultimate vertical bearing capacity and final pressure value
静压桩的单桩竖向抗压极限承载力与施工终压力值之比。
2.1.23 引孔压桩法 Method of pressing pile with pre-augering
用引孔设备在桩位处预成孔，然后将预制桩放入孔内，再用压桩机施压的作业法。
2.1.24 喂桩 Pile loading
将静压桩吊入压桩机夹持机构的一道施工工序，俗称“喂桩”。
2.1.25 单桩竖向承载力特征值 Characteristic value of the vertical bearing capacity of a single pile
单桩在竖向荷载(压或拔)作用下达到破坏状态前或不适于继续承载的变形时所对应的最大荷载除以安全系数所得的承载力值。
2.1.26 浮机 Machine floating
在压桩过程中，出现压桩机部分底盘脱离地面成悬空的状态，俗称“浮机”。
2.2 符号
2.2.1 抗力和材料性能
Ec——静压桩桩身混凝土的弹性模量；
fc——混凝土轴心抗压强度设计值；
fnk——填芯混凝土与管桩内壁的粘结强度标准值；
Fptk——管桩预应力钢筋的抗拉强度标准值；
fy——钢筋的抗拉强度设计值；
qsia——单桩第i层土(岩)的侧阻力特征值；
qpa——单桩的端阻力特征值；
qc——静力触探锥头阻力；
Ra——单桩竖向抗压承载力特征值；
Rha——单桩水平承载力特征值；
Rta——单桩竖向抗拔承载力特征值；
Rm——桩身的抗弯承载力设计值；
Rp——静压桩桩身竖向承载力设计值；
σpc——预应力管桩混凝土有效预压应力值；
Pjmax——桩身抱压允许压桩力。
2.2.2 作用和效应
Fk——相应于荷载效应标准组合时，作用于桩基承台顶面的竖向力；
Gk——桩基承台和承台上方土自重标准值；
Gp——静压桩自重；
Hk——相应于荷载效应标准组合时，作用于承台底面的水平力；
Hk——相应于荷载效应标准组合时，作用于任一根桩桩顶的水平力；
Mxk——相对于荷载效应标准组合时，作用于承台底面通过群桩形心x轴的弯矩；
Myk——相对于荷载效应标准组合时，作用于承台底面通过群桩形心y轴的弯矩；
M——相应于荷载效应基本组合时的单桩弯矩设计值；
N——实测的标准贯入击数；
N′——校正后的标准贯入击数；
Nk——层标准贯入实测击数的标准值；
Pze——静压桩施工终压力值；
Qk——相应于荷载效应标准组合时的轴心竖向力作用下任一根桩的竖向力；
Qik——相应于荷载效应标准组合时的偏心竖向力作用下第i根桩的竖向力；
Qt——相应于荷载效应基本组合时的单桩竖向拔力设计值；
Qtk——相应于荷载效应标准组合时，作用于单桩顶部的竖向拔力；
Ymax——液压式压桩机最大压桩力。
2.2.3 几何参数
A——静压桩截面面积；
Aa——管桩单根预应力钢筋的公称截面面积；
Ap——静压桩桩端水平投影面积；
b——静压方桩边长；
d——静压管桩外直径；
d1——静压管桩内直径；
h——静压桩的入土深度；
hb——静压桩桩端进入持力层深度；
L——单节桩长；静压桩的入土深度；
I——静压桩截面惯性矩；
La——桩顶填芯混凝土深度；
li——静压桩穿越第i层土(岩)的厚度；
Up——静压桩桩身外周长。
2.2.4 计算系数
α——标准贯入试验的触探杆长度校正系数；土的恢复系数；静压桩的水平变形系数；
β——竖向抗压极限承载力与终压力的相关系数；
λi——抗拔摩阻力折减系数；
ξp——静压桩桩端阻力修正系数；
ψc——成桩工艺系数。
3 静压桩基础的岩土工程勘察
3.0.1 静压桩基础的岩土工程勘察点，其平面布设、深度以及勘探深度范围内每一主要土层的取样和测试要求，除应符合现行国家标准《岩土工程勘察规范》GB 50021和《高层建筑岩土工程勘察规程》JGJ 72的有关规定外，尚应符合下列规定：
1 勘探布点间距宜取12m～24m，且每个单位工程的勘探孔不宜少于5个，其中控制性勘探孔的数量不应少于勘探孔总数的1/2且不得少于2个。当地质条件复杂时，应适当加密勘探孔；
2 一般性勘探孔深度应深入预估桩端持力层以下3m～5m；控制性勘探孔深度应深入预估桩端持力层以下5m～10m；
3 应对施工场地表土层进行详细勘察。勘察时应采用轻便动力触探、取土样、标准贯入试验等手段，准确查明表层3m厚土层的承载能力。
3.0.2 设计拟选用静压桩作基础时，岩土工程勘察应根据岩土层特点适当增加标准贯入或重型圆锥动力触探、双桥探头静力触探等原位试验。
3.0.3 当进行标准贯入试验时，应符合下列规定：
1 控制性勘探孔深度范围内的每一土层和全风化、强风化岩层，均应进行标准贯入试验。其中在淤泥、淤泥质土层中应每层测试一次；在硬塑～坚硬黏土层、残积土层及全风化岩层中，应每2m厚测试一次；遇中密～密实砂层时，应每1m厚测试-一次；拟作桩端持力层的土(岩)层应每1m厚测试一次；
2 一般性勘探孔宜在拟作桩端持力层中每1m厚测试一次；
3 在拟作桩端持力层的土(岩)层中作标准贯入试验时，当锤击数已达100击而贯入深度不足30cm时，可终止试验，并应记录100击时的实际贯入深度，但钻孔深度仍应符合3.0.1条的有关规定。
3.0.4 当采用双桥探头静力触探试验时，除应符合国家标准《岩土工程勘察规范》GB 50021的有关规定外，尚应贯入至锥尖阻力qc≥20MPa的岩土层5m左右或静探力≥300kN才能终孔。3.0.5 当选用全风化、强风化岩层中的桩侧摩阻力特征值和端阻力特征值的经验值时，应采用按钻杆长度校正后的标准贯入击数。校正后的标准贯入击数N′应按下列公式计算：
N′＝αN (3.0.5)
式中：N′——校正后的标准贯入击数；
N——实测的标准贯入击数；
α——钻杆长度校正系数，可按表3.0.5采用。
表3.0.5 钻杆长度校正系数
杆长(m) ≤3 6 9 12 15 18 21
校正系数α 1.00 0.92 0.86 0.81 0.77 0.73 0.70
杆长(m) 24 27 30 33 36 39 ≥42
校正系数α 0.67 0.64 0.61 0.58 0.55 0.52 0.49
3.0.6 花岗岩的强风化、全风化岩及残积土类，可采用实测标准贯入击数N来划分，N≥50为强风化岩；50＞N≥30为全风化岩；N＜30为残积土。其他岩石的强风化、全风化岩类的划分可参照执行。估算压桩深度时则应采用校正后的标准贯入击数N′。
3.0.7 岩土工程勘察中应对工程场地中的水和土对预制桩的腐蚀性进行评价；当有足够经验或充分资料认定工程场地的水或土对建筑材料不具腐蚀性时，可不取样做腐蚀性指标的测试；否则，应取水试样或土试样进行试验。水试样和土试样的取样方法、水和土腐蚀性指标的测试以及腐蚀性评价应按国家标准《岩土工程勘察规范》GB 50021的有关规定执行。
3.0.8 静压桩基础的岩土工程勘察报告应符合国家标准《岩土工程勘察规范》GB 50021的有关规定，并宜详列下列内容：
1 工程概况、场地位置、地形及地貌、各岩土层的名称、特征的叙述，以及所处地貌单元、主要岩土层的地质年代、成因的分析论证；
2 对建筑场地的不良地质现象，如孤石、坚硬夹层、岩溶、土洞、构造断裂的分布及成因、岩面坡度对桩端稳定性的影响等，有明确的判断结论；
3 地下水类型、稳定水位及其变化幅度；
4 场地地下水和地基土对混凝土预制桩腐蚀性评价的结论；
5 抗震设防区按地震烈度提供的可液化地层分布和判定资料；
6 标准贯入试验及其他原位测试试验成果；
7 根据表土3m厚深范围内土层承载力对静压桩施工是否出现陷机的可能性所作出的评估；
8 提出选择桩端持力层、沉桩可行性的建议；
9 提出符合静压桩基础的侧摩阻力特征值和端阻力特征值；预估单桩竖向承载力特征值及其变形特征；
10 对场地存在扰动后易软化的风化岩层作出评估，提出应对措施；
11 评价压桩对周边环境的影响；
12 勘探点平面布置图、工程地质柱状图、工程地质剖面图、强风化岩等可作为桩端持力层的岩土层面的等高线图及岩芯彩色照片等。
4 静压桩基础设计
4.1 一般规定
4.1.1 根据建筑规模、功能特征、对差异变形的适应性、场地地基和建(构)筑物体型的复杂性以及由于桩基问题可能造成建(构)筑物破坏或影响正常使用的程度，将静压桩基础设计分为表4.1.1所列的三个设计等级。静压桩基础设计时，应根据表4.1.1确定设计等级。
表4.1.1 静压桩基础设计等级
设计等级 建筑类型
甲级 (1)重要的工业与民用建筑；
(2)30层以上或高度超过100m的高层建筑；
(3)体形复杂、层数相差超过10层的高低层连成一体的建筑物；
(4)对地基变形有特殊要求的建(构)筑物；
(5)场地和地基条件复杂的七层以上的一般建筑物及坡地、岸边建(构)筑物；
(6)对原有工程影响较大的新建建(构)筑物；
(7)大跨度(≥60m)结构建筑；
(8)大面积的多层地下建(构)筑物
乙级 除甲级、丙级以外的建(构)筑物
丙级 场地和地基条件简单、荷载分布均匀的7层及7层以下的一般建筑，次要的轻型建(构)筑物
4.1.2 静压桩基础设计应具备下列基本资料：
1 符合本规程第3章规定的岩土工程勘察报告；
2 建筑场地与环境条件，包括高压架空线及地下管线、地下构筑物的分布，可能受压桩影响的临近建(构)筑物的安全等级、地基及基础情况，压桩机进退场及现场运行条件等；
3 建(构)筑物上部结构类型及形式，荷载大小、分布及性质，生产工艺和设备对基础沉降及水平位移的要求；
4 建筑场地的总平面图、建(构)筑物地下室或首层结构平面图；
5 抗震设防的有关资料；
6 可选用的静压桩规格和型号、单节桩长、接头形式及供应条件；
7 压桩设备性能及其对地质条件的适应性以及压边桩的能力。
4.1.3 静压桩基础应根据具体条件分别进行下列计算和验算：
1 应根据静压桩基础的使用功能和受力特性分别进行桩基的竖向承载力计算和水平承载力计算；
2 应对桩身和承台结构承载力进行计算；还应按吊装、运输和喂桩作业时的受力情况进行桩身承载力验算；
3 当桩端平面以下存在软弱下卧层时，应进行下卧层承载力验算；
4 对位于坡地、岸边的静压桩基础，应进行整体稳定性验算；位于大面积淤泥、淤泥质土地区的静压桩基础，当基坑开挖、基坑周边有堆载时，应进行整体稳定性验算，并采取有关防治措施；
5 对于抗拔的静压桩基础，应进行单桩和群桩的抗拔承载力计算；
6 对于抗震设防区的静压桩基础，应进行抗震承载力验算；
7 设计等级为甲级的以第四系土层、全风化岩层作为桩端持力层的静压桩基础或设计等级为乙级的体形复杂、荷载分布明显不均匀或桩端平面以下存在软弱土层的静压桩基础应进行沉降计算；
8 对受水平荷载较大，或对水平位移有严格限制的静压桩基础，应进行水平位移验算；
9 当使用条件要求限制混凝土裂缝时，尚应对静压桩基础进行抗裂或裂缝宽度验算。
4.1.4 静压桩基础设计时，所采用的作用效应组合及相应的抗力与变形限值应符合下列规定：
1 按单桩承载力确定桩数和布桩时，采用传至承台底面的荷载效应的标准组合；相应的抗力采用单桩承载力特征值；
2 计算荷载作用下的桩基沉降和水平位移时，采用荷载效应的准永久组合，不计入风荷载和地震作用，相应的限值为桩基变形允许值。计算水平地震作用、风载作用下的桩基水平位移时，采用水平地震作用、风载效应的标准组合；
3 验算坡地、岸边静压桩基础的整体稳定性时，采用荷载效应的标准组合；
4 在计算静压桩基础承台内力、确定承台尺寸、配筋和验算静压桩桩身强度时，采用传至承台表面的荷载效应的基本组合。相应的抗力采用承载力设计值。当进行承台和桩身裂缝验算时，分别采用荷载效应的标准组合和荷载效应的准永久组合。
4.1.5 在进行静压桩基础结构构件的截面承载力计算或验算时，可按下列规定确定相应的荷载效应基本组合设计值S，取其不利者：
1 永久荷载与竖向可变荷载组合：
计算时已考虑组合值系数(即活荷载折减)，取
S＝1.35Sk (4.1.5-1)
计算时组合值系数取1(即不考虑活荷载折减)，取
S＝1.30Sk (4.1.5-2)
2 永久荷载与可变荷载(包括竖向荷载、风、地震作用等)组合，取
S＝1.25Sk (4.1.5-3)
并应满足 S≤R (4.1.5-4)
式中：R——静压桩基础结构构件抗力的设计值(kN)，按有关建筑结构设计规范的规定确定；
Sk——荷载效应的标准组合值(kN)。
4.1.6 静压桩的平面布置可按下列原则进行：
1 相邻桩的中心距应满足表4.1.6中的要求；
表4.1.6 相邻桩中心距的要求
桩基情况 相邻桩中心距要求
独立承台内桩数超过30根；大面积群桩 不宜小于4.0d(b)
独立承台内桩数超过9根，但不超过30根；条形承台内桩排数超过2排 不宜小于3.5d(b)
其他情况 不得小于3.0d(b)
注：1 相邻桩中心距指两根相邻桩截面中心点之间的距离；
2 d为管桩的外径，b为方桩的边长；
3 当独立承台内桩数超过9根，或条形承台内桩排数超过2排，且桩周土为饱和黏性土时，相应桩的中心距宜比表中值增大0.5d(b)；
4 当采用减少挤土效应的措施时，相邻桩的中心距可比表中值适当减少，但不得小于3.0d(b)。
2 采用多桩或群桩时，宜使桩群承载力合力点与其上构件竖向永久荷载作用的合力中心相重合，并使基桩在承受水平力和弯矩方向有较大的抵抗矩；
3 对于桩箱基础、剪力墙结构桩筏(含平板和梁板式承台)基础，宜将桩布置在墙下；
4 同一结构单元宜避免同时采用摩擦桩和端承桩以及同时采用浅基础和静压桩基础。当受条件限制不得不采用时，则应估计其可能产生的差异沉降对上部结构的影响，必要时应有相应的加强措施。
4.1.7 静压桩用作摩擦型桩时，其长径比不宜大于100；用作端承型桩时，其长径比不宜大于60。当静压桩穿越厚度较大的淤泥等软弱土层或可液化土层时，应考虑桩身的稳定性及对承载力的影响。
4.1.8 桩端持力层应按本规程1.0.7条的规定进行选择。桩端全断面进入持力层的深度，对于黏性土、粉土、全风化岩等，不宜小于2d(b)；砂土不宜小于1.5d(b)；碎(卵)石类土、强风化岩等，不宜小于1.0d(b)。
4.1.9 单桩承台应沿两个主轴方向设置基础连系梁；双桩承台应至少在短轴方向设置基础连系梁。
4.1.10 在满足相邻桩中心距要求的前提下，单个承台下多桩及群桩基础总的承载力特征值可视为各单桩承载力特征值之和。
4.1.11 基础混凝土结构的耐久性设计应符合现行国家标准《混凝土结构设计规范》GB 50010中的有关规定。承台和基础连系梁的混凝土强度等级不得低于C25。
4.1.12 静压桩基础承台设计应符合现行广东省标准《建筑地基基础设计规范》DBJ 15—31中有关承台计算及构造要求的规定。
4.1.13 当施工场地表土层承载力特征值≤120kPa，或勘察报告中提出静压桩施工出现陷机可能性的评估结论时，应对场地进行加固处理并提出具体的处理意见。
4.2 桩的种类、连接及选用
4.2.1 静压桩的种类可分为静压方桩和静压管桩。各类桩应符合下列要求：
1 静压方桩应符合行业标准《预制钢筋混凝土方桩》JC934的有关规定。其构造设计可参照国家建筑标准设计图集《预制钢筋混凝土方桩》04G361中的有关内容，但静压方桩的配筋率、保护层厚度、混凝土强度等级以及接头的抗弯性能均应符合附录A的要求。建筑工程中常用静压方桩的边长为300mm、350mm、400mm和450mm。
2 静压管桩应符合国家标准《先张法预应力混凝土管桩》GB 13476的有关规定。静压管桩的结构构造和桩身质量要求尚应符合附录A的要求。管桩按混凝土强度等级分为预应力混凝土管桩(代号：PC)和预应力高强混凝土管桩(代号：PHC)。PC桩的混凝土强度等级不得低于C60，PHC桩的混凝土强度等级不得低于C80。建筑工程中常用静压管桩的外径为300mm、400mm、500mm和600mm。
4.2.2 静压方桩的接头应符合下列规定：
1 每根桩的接头数量不宜超过3个；
2 接头宜采用焊接法，不得采用硫磺胶泥锚接法；
3 焊接接头宜采用水平焊缝的构造形式，也可参照国家建筑标准设计图集《预制钢筋混凝土方桩》04G361中的相关形式进行设计；采用其他的新型接头，必须通过广东省有关建设行政主管部门组织的技术鉴定；
4 接头处的极限弯矩应大于桩身的极限弯矩。
4.2.3 静压管桩的接头应符合下列规定：
1 每根桩的接头数量不宜超过3个；
2 接头处的极限弯矩应大于桩身的极限弯矩；
3 当采用焊接接头时，应符合5.4.10条的规定；当采用机械啮合接头时，应符合5.4.11条的规定。采用其他的新型接头，必须通过广东省有关建设行政主管部门组织的技术鉴定。
4.2.4 机械啮合接头适用于φ300、φ400、φ500和φ600的A型和AB型管桩。其中连接销、连接板、弹簧和连接盒的材料、尺寸及制作要求应符合广东省标准《预应力混凝土管桩机械啮合接头技术规程》DBJ 15—63的规定。
4.2.5 下列条件之一的静压管桩宜采用机械啮合接头：
1 地下水或地基土对管桩有弱腐蚀或中腐蚀作用时；
2 基桩为抗拔桩时；
3 当桩数较多较密集、挤土效应较大时；
4 在环境温度低于0℃或长期风雨天作业时。
4.2.6 采用电焊焊接接头的抗拔管桩，焊缝坡口应严格按附录A表A.0.11中规定的坡口尺寸(w×la)进行制作；焊缝应连续饱满。必要时，应根据具体要求设置桩端锚固筋，或适当加大端板厚度。
4.2.7 静压桩应根据工程地质等条件选择合适的桩尖。静压管桩基础必须设置桩尖。桩尖的构造应符合下列规定：
1 桩尖宜用钢板制作，钢板性能应符合国家标准《优质碳素结构钢技术条件》GB 699或《碳素结构钢》GB/T 700的有关规定，材质应采用Q235B；桩尖制作应符合国家标准《钢结构焊接规范》GB 50661的有关规定；
2 静压方桩的桩尖可将主筋合拢焊在桩尖中心的辅助钢筋上；在密实砂层和碎(卵)石类土中及强风化岩层中，可在桩尖处外包钢板桩靴；带桩靴的桩尖构造可参照国家建筑标准设计图集《预制钢筋混凝土方桩》04G361中的有关内容；
3 常用静压管桩宜选用封口型桩尖。常用静压管桩的桩尖构造图可参见附录B。
4.2.8 静压方桩与承台连接时，桩顶嵌入承台深度宜取50mm～100mm，伸入承台内的纵向受力钢筋应符合下列规定：
1 对于抗压桩，应将桩本身的纵向受力钢筋全部锚入承台内，锚固长度不宜小于35倍纵向受力钢筋直径；
2 对于抗拔桩，应将桩本身的纵向受力钢筋全部锚入承台内，锚固长度不得小于45倍纵向受力钢筋直径。
4.2.9 静压管桩与承台连接时，应采用桩顶填芯混凝土中埋设连接钢筋的连接方式，桩顶嵌入承台内的长度宜取50mm～100mm，并应符合下列规定：
1 填芯混凝土应是补偿收缩混凝土，其强度等级不得低于C30；填芯混凝土深度：承压桩不得小于2d且不得小于1.2m；抗拔桩应按4.2.10条规定计算确定，且不得小于2.0m；
2 连接钢筋数量不宜少于4根，埋入填芯混凝土部分的箍筋应为φ6@200(4根连接钢筋)或φ8@200((多于4根连接钢筋)；
3 埋入桩顶填芯混凝土中的连接钢筋长度应与桩顶填芯混凝土深度相同；
4 承压桩的连接钢筋数量和规格，可按下列要求采用：4Ф14(φ300桩)、4Ф16(φ400桩)、4Ф20(φ500桩)和4Ф25(φ600桩)；
5 连接钢筋锚入承台内的长度：承压桩不宜小于35倍连接钢筋直径；抗拔桩不得小于45倍连接钢筋直径。
4.2.10 抗拔管桩的桩顶填芯混凝土深度和连接钢筋公称截面总面积应按下列公式计算：
(4.2.10-1)
(4.2.10-2)
式中：La——桩顶填芯混凝土深度(mm)，不应少于2.0m；
As——连接钢筋公称截面总面积(mm2)；
Qt——相应于荷载效应基本组合时的单桩竖向拔力设计值(N)；
fnk——填芯混凝土与管桩内壁的粘结强度标准值，宜由现场试验确定。当缺乏试验资料时，C30的补偿收缩混凝土fnk可取0.60～0.70N/mm2；
Upn——管桩内孔圆周长(mm)；
fy——钢筋的抗拉强度设计值(N/mm2)。
4.2.11 静压方桩的选用应考虑工程的具体情况：抗震设防烈度小于7度地区可选用A、B、C型方桩，7度或建筑场地类别为Ⅰ、Ⅱ类的8度地区应选用B、C型方桩，且所选桩型的各项力学指标应满足桩基的设计要求和有关标准的规定；非预应力的静压方桩不宜用作抗拔桩。
4.2.12 静压管桩的选用应遵照下列原则：
1 用于抗震设防烈度为建筑场地类别Ⅰ、Ⅱ类的8度地区的管桩基础工程，或设计等级为甲级的以及工程地质条件较复杂的设计等级为乙级的管桩基础工程，宜选用AB型或B型、C型管桩，且所选桩型的各项力学指标应满足桩基的设计要求和有关标准的规定；设计等级为甲级的管桩基础工程，不得选用φ300管桩；
2 在地下水或地基土对混凝土、钢筋和钢零部件有弱腐蚀或中腐蚀环境下应用的管桩基础工程，应选用AB型或B型、C型且桩身合缝和端头处不得有修补痕迹的管桩，不得选用φ300管桩，同时应按4.2.13条规定根据不同的腐蚀性等级采用相应的防腐蚀措施；
3 抗拔桩宜选用AB型或B型、C型管桩，同时应按4.2.3条～4.2.6条的规定选择合适的管桩接头形式；φ300管桩不宜选作抗拔桩。
4.2.13 在地下水或地基土对静压桩的混凝土、钢筋和钢零部件有腐蚀作用的环境下应用静压桩时，其防腐蚀措施可按下列规定执行：
1 用于弱腐蚀或中腐蚀环境下的静压桩，其钢筋的保护层厚度不应小于40mm，静压管桩的桩尖应采用封口型；
2 在强腐蚀的环境下，不宜采用静压桩。当必须选用静压桩时，应经试验论证，并采取可靠措施，确能满足防腐蚀要求时方可使用；
3 桩身应减少接头数量，宜采用单节桩。若需要接桩时，接头宜设置在微腐蚀土层中，不得设置在干湿交替的环境中；
4 在中腐蚀的环境下，静压管桩的接头宜采用机械啮合接头，连接销、连接盒内应涂上或注入沥青涂料；焊缝坡口应焊满封闭；桩孔底部应灌注高度为1.5m～2.0m的C30细石混凝土，必要时可将管桩内孔全部灌满；
5 在硫酸盐的中腐蚀环境下应用的静压桩，桩身混凝土应采用抗硫酸盐水泥，或应掺加矿物掺合料。在氯离子的中腐蚀环境下应用的静压桩，应掺加钢筋阻锈剂(但不得采用亚盐酸类的阻锈剂)和矿物掺合料。当有多类介质同时作用时，应分别满足各自的防护要求，但相同的防护措施不迭加。