關(guān)鍵詞:稻雞 板樹(shù)碼頭 降水 位移

The impact on sheet-pile wharf in sandy foundation due to foundation pit dewatering

MA Yong-ping HUANG Hai-yun

(China Shipbuilding NDRI Engineering Co.,Lid.,)

Abstract:During dry dock construction in sandy site,the dewatering of dock foundation pit affects the displacemen of sheet-pile wharf nearby. It can even appear the phenomenon that the sheet pile wall moves to the shore side. Based on a new shipyard project in Singaporethis paper presents the analysis and rescarch for the results of the sheet pile wall displacement monitoring during the dewatering work, and also presents numerical simulation by the application of finite element program PLAXIS.The result of numerical simulation further verified the correctness of the results of displacement monitoring.

Key words: Dry dock, sheet-pile wharf, dewatering, displacement 

2 PLAXIS 模擬計(jì)算

2.1計(jì)算模型及模型參數(shù)

本文分別計(jì)算考慮基坑降水和不考慮基坑降水2個(gè)模型進(jìn)行比較?？紤]基坑降水的計(jì)算模型如圖3所示,采用PLAXIS程序進(jìn)行數(shù)值模擬計(jì)算,計(jì)算模型中材料模型采用排水條件下的摩爾-庫(kù)倫模型。將基坑開(kāi)挖、板樁碼頭施工及開(kāi)挖等各工況進(jìn)行模擬計(jì)算。土層參數(shù)及地下水位選擇見(jiàn)表2及表3。不考慮基坑降水模型也采用排水條件下的摩爾-庫(kù)倫模型,土層參數(shù)同表2,板樁碼頭的剩余水位,按英標(biāo) BS6349M中的規(guī)定取 1.3m,計(jì)算模型見(jiàn)圖4。表2

2.2 計(jì)算結(jié)果

分析 PLAXIS 有限元計(jì)算結(jié)果可知，考慮基坑降水的模型，當(dāng)計(jì)算工況為碼頭及基坑均開(kāi)挖至設(shè)計(jì)標(biāo)高,水位為表3中各標(biāo)高時(shí),計(jì)算的板樁墻的最大位移位于板樁墻頂,并且位移為向岸側(cè)移動(dòng),向海側(cè)的位移僅發(fā)生在開(kāi)挖面以上一段區(qū)域，此模型的位移結(jié)果圖見(jiàn)圖 5。而不考慮基坑降水的模型,計(jì)算工況為碼頭開(kāi)挖至設(shè)計(jì)標(biāo)高，剩余水位為 1.3m，此工況計(jì)算的位移結(jié)果為正常情況下的位移趨勢(shì)，最大位移發(fā)生在開(kāi)挖面與拉桿中間部位，模型的位移結(jié)果圖見(jiàn)圖 6。

在考慮基坑降水的模型計(jì)算時(shí)，增加計(jì)算了碼頭開(kāi)挖至設(shè)計(jì)標(biāo)高、塢墻回填、地下水位恢復(fù)為正常地下水位(剩余水位為 1.3m)時(shí)的工況，此工況的計(jì)算板樁墻位移與不考慮基坑降水模型計(jì)算的板樁墻位移基本相同。此工況的計(jì)算位移結(jié)果圖見(jiàn)圖7。各計(jì)算模型的位移結(jié)果匯總見(jiàn)表4。