旋挖钻桩基础施工方案.doc

旋挖钻桩基础施工方案 旋挖钻桩基施工方案
一、 工程概况
 某分离式立交桥为双向双幅四车道预应力简支梁结构，起止桩号为K12+425.29~K13+090.71，共计665.42m，即从1#桥台至34#桥台共34跨。2002年9月业主对该桥进行了一次重大设计变更，将34#桥台至另一标段1#桥台段原设计的填土路基修改为高架桥，两端之间增加40跨高架桥，桥梁总长变更为74跨。下构墩柱基础为系梁，每半幅系梁基础均为两根直径1500mm的钻孔灌注桩，共计增加路改桥160根桩，桩基为25#砼,桩长为26.8米。
二、 施工前现场处理平面布置图（见附图1）   
路改桥段设计修改前为填土路基，其原地面全为鱼塘和低洼稻田，且正式设计修改前对路基范围内的7个鱼塘已进行了清淤换填砂卵石，换填高度超出地下水位接近施工便道的顶面，后业主方要求将已回填好的砂卵石约3万方全部挖出来运到另一处作为回填材料，这样该段设计路改桥后原地形又恢复为原来的7个鱼塘和低洼地。进行桥梁下构施工前必须对场地进行处理，考虑到旋挖钻机设备自重较重接近80吨，为保证钻孔施工的桩位准确性和设备的安全性，对场地处理的回填料必须慎重选择，考虑到附近没有好的土源，到路基取土场取土考虑其成本又太高
Pile Foundation Construction Rotary drilling program Rotary Drilling Pile Foundation Construction Programme
First, project survey
 Overpass of a separate four-lane two-way dual-rate structure of prestressed beams, beginning and ending Stake for the K12 +425.29 ~ K13 +090.71, a total of 665.42m, from 1 # to 34 # bridge abutment with a total of 34 cross. September 2002 the owners of the bridge was a major design change, the abutment 34 # 1 # Bridge Lot to another section of the original design of the filling station was revised to elevated roadbed, an increase of 40 across the viaduct between the two ends of the bridge length changed to 74 cross. Under the pier base and beam structure, the basis of each Banfu tie beam are two 1500mm diameter bored piles for a total increase of 160 Road Reconstruction and Bridge piles, pile of 25 # concrete, pile length is 26.8 meters.
Second, dealing with pre-construction site layout plan (see photo 1)
Road Reconstruction and plot design changes before filling subgrade, the original low-lying ground whole fish ponds and rice fields, and the formal design changes before the foundation of seven ponds within the scope of the dredging has been carried sand and gravel replacement, replacement high Construction of pavement beyond the water table close to the top surface, after the owner's request to have a good sand and gravel backfill all excavated to about 3 of transport to another as a backfill material, so that the design of road section of the bridge after the change has reverted to the original topography The original seven fish ponds and low-lying land. Conducted under the bridge structure before construction on the venues deal, taking into account rotary drilling rig equipment, heavy weight close to 80 tons, in order to ensure the accuracy of Boring Pile and equipment safety, on site processing of the filler must be carefully chosen , taking into account the absence of good soil near the source, to the subgrade soil obtaining dug into account the cost too high