波浪循環荷載作用下濱海軟土水平向動力特性試驗研究

郝斌　趙玉成　劉珍巖　李占嶺　盧二巖

摘要：為研究海上風電樁基在波浪荷載作用下，產生水平向循環荷載對樁基周圍土體動力特性的影響，以唐山地區濱海軟土為研究對象，通過室內動三軸試驗，研究不同圍壓、動應力幅值和振動次數條件下對軟土水平向動力特性的影響。結果表明：軟土水平向動強度隨圍壓增加而增加，隨振動次數增加而減小；動應力幅值增大，破壞振次減小；水平向動應變εd隨振動次數增加變大，且動應力幅值越大，增速越明顯，變化規律遵循Monismith模型；動應力幅值改變時，軟土水平向動模量變化明顯，當圍壓減小，動彈性模量減小；曹妃甸軟土水平向間具有明顯的結構性，不同圍壓條件下，隨動應力幅值增加動阻尼比均表現增大趨勢。

關鍵詞：濱海軟土；循環荷載；水平向動力特性；動三軸試驗

中圖分類號：TU411.8

文獻標志碼：A文章編號：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

風電產業迅速發展，受陸地條件制約，地廣人稀的海岸灘涂和海上風電產業得到重視，海上風電場建設步入發展的快車道，但沿海地區廣泛分布著工程性質較差的軟土。風電設施建成后樁基周圍土體受到常見的動力循環荷載——波浪荷載[1]長期作用，在波浪荷載作用下土體產生的累積變形、強度及穩定性問題成為眾多學者關注的重點[2]。波浪荷載作為一種作用時間長、振動較為規則的循環荷載，需考慮循環效應對樁基周圍土體動力特性的影響。應用GDS室內動三軸試驗系統研究波浪荷載作用下軟土水平向的動力特性。……