波浪循環(huán)荷載作用下濱海軟土水平向動(dòng)力特性試驗(yàn)研究

郝斌　趙玉成　劉珍巖　李占嶺　盧二巖

摘要：為研究海上風(fēng)電樁基在波浪荷載作用下，產(chǎn)生水平向循環(huán)荷載對(duì)樁基周圍土體動(dòng)力特性的影響，以唐山地區(qū)濱海軟土為研究對(duì)象，通過(guò)室內(nèi)動(dòng)三軸試驗(yàn)，研究不同圍壓、動(dòng)應(yīng)力幅值和振動(dòng)次數(shù)條件下對(duì)軟土水平向動(dòng)力特性的影響。結(jié)果表明：軟土水平向動(dòng)強(qiáng)度隨圍壓增加而增加，隨振動(dòng)次數(shù)增加而減??；動(dòng)應(yīng)力幅值增大，破壞振次減小；水平向動(dòng)應(yīng)變?chǔ)興隨振動(dòng)次數(shù)增加變大，且動(dòng)應(yīng)力幅值越大，增速越明顯，變化規(guī)律遵循Monismith模型；動(dòng)應(yīng)力幅值改變時(shí)，軟土水平向動(dòng)模量變化明顯，當(dāng)圍壓減小，動(dòng)彈性模量減??；曹妃甸軟土水平向間具有明顯的結(jié)構(gòu)性，不同圍壓條件下，隨動(dòng)應(yīng)力幅值增加動(dòng)阻尼比均表現(xiàn)增大趨勢(shì)。

關(guān)鍵詞：濱海軟土；循環(huán)荷載；水平向動(dòng)力特性；動(dòng)三軸試驗(yàn)

中圖分類號(hào)：TU411.8

文獻(xiàn)標(biāo)志碼：A文章編號(hào)：16744764（2016）01011606

Abstract：

A series of dynamic triaxle test on soft soil in Tangshan Binhai area was carried out to understand the horizontal dynamic characteristics of the soil around the offshore wind power pile foundation under wave load. The influence of confining pressure， dynamic stress amplitude and vibration frequency on horizontal dynamic characteristics of soft soil were studied. The results show that the horizontal dynamic strength of soft soil increases with the increase of confining pressure increases，and decreases with the increase of vibration. When the dynamic stress amplitude increases， the vibration times decreases. The horizontal dynamic strain εd increases with the increase of vibration frequency， and the larger the dynamic stress amplitude is， the more significant the growth is. The change agrees well with that of the Monismith model. The change of the horizontal dynamic modulus of soft soil is significantly influenced by the dynamic stress amplitude. When confining pressure decreases， dynamic modulus decreases. The Caofeidian soft soil has distinct structural horizontal dynamic characteristics. Under different confining pressures， the damping ratio shows an increasing trend when dynamic stress amplitude increases.

Keywords：coastal soft soil； cyclic loading； horizontal dynamic characteristics； dynamic triaxial test

風(fēng)電產(chǎn)業(yè)迅速發(fā)展，受陸地條件制約，地廣人稀的海岸灘涂和海上風(fēng)電產(chǎn)業(yè)得到重視，海上風(fēng)電場(chǎng)建設(shè)步入發(fā)展的快車道，但沿海地區(qū)廣泛分布著工程性質(zhì)較差的軟土。風(fēng)電設(shè)施建成后樁基周圍土體受到常見(jiàn)的動(dòng)力循環(huán)荷載——波浪荷載[1]長(zhǎng)期作用，在波浪荷載作用下土體產(chǎn)生的累積變形、強(qiáng)度及穩(wěn)定性問(wèn)題成為眾多學(xué)者關(guān)注的重點(diǎn)[2]。波浪荷載作為一種作用時(shí)間長(zhǎng)、振動(dòng)較為規(guī)則的循環(huán)荷載，需考慮循環(huán)效應(yīng)對(duì)樁基周圍土體動(dòng)力特性的影響。應(yīng)用GDS室內(nèi)動(dòng)三軸試驗(yàn)系統(tǒng)研究波浪荷載作用下軟土水平向的動(dòng)力特性?！?br>