地中壁之地表加載液化防制效果 之離心模型試驗

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Title:	地中壁之地表加載液化防制效果之離心模型試驗
Authors:	鄭皓謙;cheng,hao-chien
Contributors:	土木工程學系
Keywords:	液化防制;殘餘應力;地中壁;土壤液化;超額孔隙水壓;地工離心機;加速度放大效應;沉陷量;centrifuge shaking table test;soil liquefaction;shaking table test;underground wall
Date:	2015-08-21
Issue Date:	2015-09-23 10:13:13 (UTC+8)
Publisher:	國立中央大學
Abstract:	摘要台灣位於地震帶，液化是伴隨地震而來的災害，而地中壁是非常有效的防治方法，原理是以剛性壁體限制土體在地震時之變形量，使超額孔隙水壓比(Ru)小於1.0，就可達到防治效果，即使地震太大產生液化，也可束制地基土壤不使產生側向流動破壞，控制其沉陷量。本研究以50g之離心試驗和振動台，進行八組組地中壁液化防制效果之離心模型試驗，沿用許漢維之地中壁模型，並加上5t/m²和10t/m²載重塊和蓋板使用，試驗進行中擷取加速度計、孔隙水壓計、土壓計、線性差動可變變壓器(LVDT)所量測到的動態數據探討(1)加速度放大倍率隨深度變化；(2)不同深度超額孔隙水壓激發與消散行為；(3)地表沉陷量歷時；(4)壁體所受側向總應力歷時等課題。研究結果顯示:(1)土壤在未達到液化狀態時，振動加速度由基盤至地表有放大趨勢；(2)在自由場加上載重塊在小振動時，可以抑制土壤液化；(3)在地中壁插入承載層時，如果加上剛接頂板，可以有效減少沉陷(4)加上載重塊時，可以加速超額孔隙水壓之消散。關鍵字：液化防制、地中壁、土壤液化、地工離心機、加速度放大效應、沉陷量、超額孔隙水壓、殘餘應力 ;Abstract A series of centrifuge shaking table tests was conducted to investigate the mitigating effect on soil liquefaction by the lattice-shaped underground wall. During the test, accelerometers, pore pressure transducers, linear variable differential transformers and micro earth pressure transducers were embedded in the soil layer to monitor the seismic response of soil deposit. The mitigating effect was evaluated by the measurements, including (1) maximum peak ground acceleration along the depth; (2) excess pore pressure histories at different depths; (3) ground settlement and (4) lateral total pressure applied on the underground wall. From the test result, it can be conclude that (1) the acceleration amplitude was amplified from the base to the surface ground before soil liquefaction. The shear wave can not propagate through the liquefied soil layer to the ground surface and leading to that the acceleration amplification was smaller than 1. (2) The upload is bigger and the mitigating effect is better. (3)The total lateral pressure acted cyclically on the underground wall and increased with increasing depth during shaking. (4) When lattice-shaped underground wall on bearing layer and it has the cap on top, it will reduce the ground settlement effective. Keywords: centrifuge shaking table test, underground wall, soil liquefaction
Appears in Collections:	[Graduate Institute of Civil Engineering] Electronic Thesis & Dissertation

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