本文選題：黑棉土 + 膨脹土��； 參考：《巖土工程學(xué)報(bào)》2017年10期

【摘要】：通過離心機(jī)試驗(yàn)研究高液限強(qiáng)膨脹性黑棉土地基中4根模型基樁在浸水條件下樁頭位移和樁身軸力的變化規(guī)律,考慮的影響因素包括樁長、樁頭荷載以及是否采用隔脹措施。通過自主設(shè)計(jì)制作的離心機(jī)內(nèi)降雨裝置和模型土層中的滲流通道實(shí)現(xiàn)黑棉土地基浸水條件。試驗(yàn)發(fā)現(xiàn),黑棉土浸水后對(duì)樁身軸力的影響分為兩階段:前期土體剛度降低階段,黑棉土遇水剛度降低后能提供的摩阻力明顯降低,使得樁身軸力增大;后期脹拔階段:黑棉土遇水膨脹隆起,對(duì)樁基產(chǎn)生向上的脹拔力,樁身軸力減小。此外,浸水引起的樁頭位移變化與樁頂受荷情況密切相關(guān):未受荷樁發(fā)生上拔位移,而荷載為625 k N的樁發(fā)生沉降位移。在樁周采取隔脹措施可以削弱甚至消除黑棉土變形對(duì)樁基的不利影響。
[Abstract]:Through centrifuge test, the variation law of pile head displacement and pile axial force of four model piles in high liquid limit and strong expansion black cotton soil foundation are studied under the condition of water immersion. The influencing factors considered include pile length, pile head load and whether to adopt expansion isolation measures. The soaking conditions of black cotton soil foundation are realized by the self-designed rainfall device in centrifuge and the seepage passage in the model soil layer. It is found that the influence of black cotton soil immersion on the axial force of pile body is divided into two stages: in the early stage of soil stiffness reduction, the frictional resistance of black cotton soil can be reduced obviously when the soil stiffness decreases, which increases the axial force of pile body; In the later stage of swelling and drawing, when the black cotton soil is swelled by water, the upward swelling force is produced and the axial force of the pile body decreases. In addition, the change of pile head displacement caused by water immersion is closely related to the load on the top of the pile: the uplift displacement occurs in the unloaded pile and the settlement displacement occurs in the pile with load of 625 KN. The negative effect of black cotton soil deformation on pile foundation can be weakened or even eliminated by taking bulging measures around the pile.
【作者單位】： 清華大學(xué)土木工程安全與耐久教育部重點(diǎn)實(shí)驗(yàn)室;中國路橋工程有限責(zé)任公司;
【基金】：國家重點(diǎn)基礎(chǔ)研究發(fā)展計(jì)劃項(xiàng)目(2014CB047003)
【分類號(hào)】：TU443;TU473.1

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本文編號(hào)：1945900