發(fā)布時間：2019-03-08 11:25

【摘要】：黃土塬地區(qū)樁基問題研究匱乏,依托隴東首棟超高層建筑,在試驗樁身上布置混凝土應(yīng)變計、鋼筋應(yīng)力計,承臺底板下和樁端布置土壓力盒,對原地基土、單樁基礎(chǔ)和單樁承臺基礎(chǔ)分別進行現(xiàn)場原位載荷試驗;利用ANSYS有限元軟件對全短樁基、全長樁基及長短樁組合樁基在豎向荷載作用下的筏板沉降變形、地基土應(yīng)力場與沉降變化進行分析。結(jié)果發(fā)現(xiàn):(1)黃土塬場地地基土夾層交互分布、濕陷性不連續(xù),存在由非濕陷性黃土變成濕陷性黃土的可能,樁周土層對樁基內(nèi)力傳遞與分布影響顯著,樁身出現(xiàn)多個中性點,濕陷性土層下限深度確定更加復(fù)雜;(2)各級荷載作用下,樁基Q-S曲線呈緩變型發(fā)展,表現(xiàn)為典型的摩擦型樁,樁身內(nèi)力發(fā)揮具有異步性;試驗加載至8 000 k N時,樁頂最大沉降為8.15 mm,單樁和單樁承臺端阻力分別僅占樁頂荷載的4.8%和2.1%;(3)單樁承臺基礎(chǔ)中承臺底部實測反力呈倒"盆"形分布、邊緣應(yīng)力較大,樁 土 承臺體系的承載性能優(yōu)于單樁基礎(chǔ);樁基礎(chǔ)設(shè)計時,可結(jié)合經(jīng)驗以承載力和最大允許變形量進行控制,提高樁身線剛度抵抗自身壓縮變形,減小樁基上部沉降;(4)長短樁組合樁基礎(chǔ)充分利用與發(fā)揮了長樁控制沉降的作用與地基土淺層承載的能力,減少了長樁數(shù)量,節(jié)省了樁基造價,值得進一步深入研究。
[Abstract]:There is a lack of research on pile foundation in Huangtuyuan area. Relying on the first super-high-rise building in East Gansu Province, the concrete strain gauge, reinforced stress gauge, earth pressure box under the bottom plate of the cap and the pile end are arranged on the test pile, and the soil pressure box is arranged under the bottom plate and the pile end of the pile. The in-situ loading tests of single pile foundation and single pile cap foundation are carried out respectively. ANSYS finite element software is used to analyze the settlement deformation of raft, stress field and settlement of soil under vertical load on full-short pile foundation, full-length pile foundation and long-short pile combination pile foundation. The results are as follows: (1) the interaction distribution of soil and interlayer on the loess plateau site, the collapsibility discontinuity, the possibility of changing from non-collapsible loess to collapsible loess, and the influence of soil layer around piles on the internal force transfer and distribution of pile foundation is obvious. There are many neutral points in the pile body, and it is more complicated to determine the lower limit depth of collapsible soil layer. (2) under the action of all kinds of loads, the QS curve of pile foundation develops slowly, which is a typical friction pile, and the internal force of pile body plays an asynchronous role; When the pile top is loaded to 8 000 k N, the maximum settlement of the pile top is 8.15 mm, and the resistance at the end of the pile cap only accounts for 4.8% and 2.1% of the pile top load, respectively. (3) in the single pile cap foundation, the measured reaction force at the bottom of the cap is inverted "basin", and the edge stress is large, and the bearing capacity of the pile-soil cap system is better than that of the single pile foundation. In the design of pile foundation, the bearing capacity and maximum allowable deformation can be controlled according to the experience, so as to improve the linear stiffness of pile body to resist self-compression deformation and reduce the settlement of the upper part of pile foundation. (4) the long-and long-pile composite pile foundation makes full use of the effect of long pile to control settlement and the bearing capacity of shallow soil, reduces the number of long pile and saves the cost of pile foundation, which is worthy of further study.
【作者單位】： 蘭州理工大學(xué)甘肅省土木防災(zāi)減災(zāi)重點實驗室;蘭州理工大學(xué)西部土木工程防災(zāi)減災(zāi)教育部工程研究中心;
【基金】：教育部創(chuàng)新團隊支持計劃項目(2013IRT13068) 甘肅省科技重大專項計劃項目(1302FKDA030)~~
【分類號】：TU473.1

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