泥浆护壁回转钻孔灌注桩工程技术交底.doc

一、 工程概况
广东科学中心主楼工程桩桩径分为φ800和φ1000两种，其中桩径为φ800的桩共404条；桩径为φ1000的桩共685条。工程桩桩端持力层为中风化泥质粉砂岩，桩端进入持力层深度为1.5～5米。采用正循环工艺成孔和清孔，桩垂直度偏差要求不大于1％，桩径偏差要求不得超过－50mm，灌注混凝土前孔底沉渣厚度要求不大于50mm。
桩身采用C35水下混凝土，混凝土保护层厚度为70mm，混凝土的防腐等级为一级防护，采用普通硅酸盐水泥。
二、 质量标准
1、 保证项目
（1） 灌注桩用的原材料和混凝土强度必须符合设计要求和施工规范的规定。
（2） 成孔深度必须符合设计要求，桩端持力层为中风化泥质粉砂岩，桩端进入持力层深度应≥hr（入岩深度）；遇软弱夹层时必须穿越软弱夹层。
（3） 桩身材料：混凝土等级为C35，为水下混凝土；钢筋HPB235级，HRB335级。纵筋的混凝土保护层厚度为70mm。混凝土最大水灰比为0.45（可加减水剂），最小水泥用量为360kg/m3，铝酸三钙含量≤8％，最大氯离子含量为0.06％，最大碱含量为3.0kg/m3。
（4） 分段钢筋笼中的纵筋采用搭接焊接长，单面搭焊10d；纵向钢筋接头应每隔一根错开，同一截面可接长50％的总钢筋面积的钢筋，相邻接头错开1000mm；螺旋箍筋与纵筋点焊，螺旋箍筋采用单面搭接焊10d接长。
First, project survey
Guangdong Science Center main building works is divided into φ800 and φ1000 pile diameter two, which piles the pile diameter φ800 of 404; pile diameter φ1000 total of 685 piles. Engineering pile tip bearing layer of weathered pelitic siltstone, pile into the support layer of depth is 1.5 to 5 meters. Circulation process by being clear hole and the hole, pile verticality deviation requirement is less than 1% deviation required pile diameter shall not exceed-50mm, the pouring of concrete required before the hole bottom sediment thickness is less than 50mm.
C35 underwater pile with concrete, concrete cover thickness to 70mm, grade level concrete corrosion protection, using ordinary portland cement.
Second, quality standards
1, ensure that the project
(1) The pile of raw materials and the strength of concrete used must meet the design requirements and construction norms.
(2) into the hole depth must meet the design requirements, pile tip bearing layer in the weathered pelitic siltstone, pile into the bearing layer depth should be ≥ hr (into the rock depth); case of weak interlayer must be through the soft interlayer.
(3) Pile material: concrete grade C35, the underwater concrete; reinforced HPB235 level, HRB335 grade. Longitudinal reinforcement of the concrete cover thickness to 70mm. Maximum water-cement ratio of concrete was 0.45 (additive water reducing agent), the minimum amount of cement as 360kg/m3, tricalcium aluminate content of ≤ 8%, the maximum chloride ion content of 0.06% and the maximum alkali content of 3.0kg/m3.
(4) above the longitudinal reinforcement steel cage welded by lap length, single lap welding 10d; longitudinal steel joints should be staggered at intervals of 1, the same section can be accessed 50% of the total length of the steel reinforcement area adjacent joints stagger 1000mm; spiral reinforcement and longitudinal reinforcement welding, lap welding of spiral hoop with one side longer then 10d.