旋挖鉆樁基礎施工方案.doc

旋挖鉆樁基礎施工方案 旋挖鉆樁基施工方案
一、 工程概況
 某分離式立交橋為雙向雙幅四車道預應力簡支梁結構，起止樁號為K12+425.29~K13+090.71，共計665.42m，即從1#橋臺至34#橋臺共34跨。2002年9月業主對該橋進行了一次重大設計變更，將34#橋臺至另一標段1#橋臺段原設計的填土路基修改為高架橋，兩端之間增加40跨高架橋，橋梁總長變更為74跨。下構墩柱基礎為系梁，每半幅系梁基礎均為兩根直徑1500mm的鉆孔灌注樁，共計增加路改橋160根樁，樁基為25#砼,樁長為26.8米。
二、 施工前現場處理平面布置圖（見附圖1）   
路改橋段設計修改前為填土路基，其原地面全為魚塘和低洼稻田，且正式設計修改前對路基范圍內的7個魚塘已進行了清淤換填砂卵石，換填高度超出地下水位接近施工便道的頂面，后業主方要求將已回填好的砂卵石約3萬方全部挖出來運到另一處作為回填材料，這樣該段設計路改橋后原地形又恢復為原來的7個魚塘和低洼地。進行橋梁下構施工前必須對場地進行處理，考慮到旋挖鉆機設備自重較重接近80噸，為保證鉆孔施工的樁位準確性和設備的安全性，對場地處理的回填料必須慎重選擇，考慮到附近沒有好的土源，到路基取土場取土考慮其成本又太高
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
 

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