自平衡試樁法室內(nèi)模型試驗與現(xiàn)場測試對比研究
發(fā)布時間：2018-08-03 20:35
【摘要】：自平衡試樁法作為一種新興的樁基檢測技術(shù)在國內(nèi)外得到了廣泛的應(yīng)用與發(fā)展,與傳統(tǒng)試樁方法相比,該法省時、省力、占地面積小且不受測試場地限制。就該測試方法國內(nèi)外主要研究自平衡上段樁樁側(cè)摩阻力與傳統(tǒng)靜壓樁、抗拔樁樁側(cè)摩阻力的區(qū)別；平衡點位置的確定和自平衡測試后的試樁能否繼續(xù)作為工程樁使用,但巖土性狀復(fù)雜,自平衡法測樁仍有不少理論與實踐問題。采用的方法包括理論分析、數(shù)值計算、現(xiàn)場測試,獲得了許多寶貴的研究成果,本文采用花崗巖殘積土為模型土對自平衡試樁法與傳統(tǒng)試樁的極限承載能力和荷載傳遞方式進(jìn)行了對比模型試驗。在樁身外側(cè)凹槽內(nèi)粘貼電阻應(yīng)變片從而可測得樁身隨埋置深度不同的應(yīng)變,得出相同邊界條件下自平衡試樁與傳統(tǒng)試樁樁側(cè)摩阻力、樁身軸力的傳遞規(guī)律,從而揭示了花崗巖殘積土中自平衡試樁法與傳統(tǒng)靜壓試樁法的荷載傳遞規(guī)律與正負(fù)摩阻力之間的關(guān)系,并且結(jié)合實體工程進(jìn)行了現(xiàn)場測試。取得了如下主要結(jié)論：(1)由于加載方式的不同,上托樁荷載自下而上傳遞,抗拔樁荷載自上而下傳遞,且傳遞的速率有所不同,上托樁荷載傳遞速率較抗拔樁小。(2)上托樁與抗拔樁樁側(cè)摩阻力隨深度分布不同,上托樁樁側(cè)摩阻力在加載點位置承擔(dān)了較大一部分,這是由局部增強效應(yīng)所引起,而抗拔樁樁側(cè)摩阻力分布較均勻,隨著荷載的增加,抗拔樁下部土層比上托樁上部土層發(fā)揮的作用要大。(3)全風(fēng)化花崗巖中樁側(cè)正負(fù)摩阻力的修正系數(shù)γ可取0.5-0.6之間。(4)荷載達(dá)到極限值之前,施加荷載時加載點附近樁體受壓徑向膨脹,同時樁體帶動樁周土位移,在樁端附近形成土拱,在上覆荷載作用下使得土拱效應(yīng)使樁側(cè)徑向應(yīng)力增加,樁側(cè)摩阻力隨之增加。(5)在全風(fēng)化和強風(fēng)化花崗巖土層中,利用砂土和碎石土的相關(guān)參數(shù)進(jìn)行試驗設(shè)計是可行的。
[Abstract]:Self-balanced pile testing technique has been widely used and developed at home and abroad as a new pile foundation testing technology. Compared with the traditional pile testing method, the method saves time and labor, occupies a small area and is not limited by the test site. This test method is mainly concerned with the difference between the lateral friction of the self-balanced pile and the traditional static pressure pile, the determination of the equilibrium point and whether the test pile can be used as the engineering pile after self-balancing test, and the difference between the friction resistance of the pile and the anti-uplift pile, the determination of the equilibrium point and whether the test pile can be used as the engineering pile after self-balancing test. However, the geotechnical properties are complex, and there are still many theoretical and practical problems in self-equilibrium pile measurement. The methods used include theoretical analysis, numerical calculation, field testing, and many valuable research results have been obtained. In this paper, granite residual soil is used as the model soil to compare the ultimate bearing capacity and load transfer mode between the self-balanced pile test method and the traditional pile test method. The strain of pile body with different buried depth can be measured by sticking resistance strain gauge in the outside groove of pile body, and the friction resistance of self-balanced pile and traditional pile under the same boundary condition can be obtained, and the transfer law of axial force of pile body can be obtained. The relationship between load transfer law and positive and negative frictional resistance of self-equilibrium pile test method and traditional static pressure pile test method in granite residual soil is revealed, and field test is carried out in combination with solid engineering. The main conclusions are as follows: (1) because of the different loading modes, the load is transferred from bottom to top, and the load of uplift pile is transferred from top to bottom, and the transfer rate is different. The load transfer rate of the upper pile is smaller than that of the uplift pile. (2) the lateral frictional resistance of the supporting pile is different from that of the uplift pile with the depth distribution, and the lateral friction of the supporting pile bears a large part at the loading point, which is caused by the local enhancement effect. However, the frictional resistance distribution of the anti-drawing pile is more uniform, and with the increase of load, (3) the correction coefficient 緯 of positive and negative frictional resistance of pile side in fully weathered granite can be between 0.5-0.6. (4) before the load reaches the limit value, When the load is applied, the pile body near the loading point expands radially under compression, while the pile body drives the soil displacement around the pile and forms a soil arch near the pile end. Under the overburden load, the soil arch effect increases the radial stress of the pile side. The pile side friction increases with it. (5) in the weathered and strongly weathered granite soil layers, it is feasible to use the relevant parameters of sand and gravel to carry out the experimental design.
【學(xué)位授予單位】：長沙理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TU473.1
本文編號：2162924
[Abstract]:Self-balanced pile testing technique has been widely used and developed at home and abroad as a new pile foundation testing technology. Compared with the traditional pile testing method, the method saves time and labor, occupies a small area and is not limited by the test site. This test method is mainly concerned with the difference between the lateral friction of the self-balanced pile and the traditional static pressure pile, the determination of the equilibrium point and whether the test pile can be used as the engineering pile after self-balancing test, and the difference between the friction resistance of the pile and the anti-uplift pile, the determination of the equilibrium point and whether the test pile can be used as the engineering pile after self-balancing test. However, the geotechnical properties are complex, and there are still many theoretical and practical problems in self-equilibrium pile measurement. The methods used include theoretical analysis, numerical calculation, field testing, and many valuable research results have been obtained. In this paper, granite residual soil is used as the model soil to compare the ultimate bearing capacity and load transfer mode between the self-balanced pile test method and the traditional pile test method. The strain of pile body with different buried depth can be measured by sticking resistance strain gauge in the outside groove of pile body, and the friction resistance of self-balanced pile and traditional pile under the same boundary condition can be obtained, and the transfer law of axial force of pile body can be obtained. The relationship between load transfer law and positive and negative frictional resistance of self-equilibrium pile test method and traditional static pressure pile test method in granite residual soil is revealed, and field test is carried out in combination with solid engineering. The main conclusions are as follows: (1) because of the different loading modes, the load is transferred from bottom to top, and the load of uplift pile is transferred from top to bottom, and the transfer rate is different. The load transfer rate of the upper pile is smaller than that of the uplift pile. (2) the lateral frictional resistance of the supporting pile is different from that of the uplift pile with the depth distribution, and the lateral friction of the supporting pile bears a large part at the loading point, which is caused by the local enhancement effect. However, the frictional resistance distribution of the anti-drawing pile is more uniform, and with the increase of load, (3) the correction coefficient 緯 of positive and negative frictional resistance of pile side in fully weathered granite can be between 0.5-0.6. (4) before the load reaches the limit value, When the load is applied, the pile body near the loading point expands radially under compression, while the pile body drives the soil displacement around the pile and forms a soil arch near the pile end. Under the overburden load, the soil arch effect increases the radial stress of the pile side. The pile side friction increases with it. (5) in the weathered and strongly weathered granite soil layers, it is feasible to use the relevant parameters of sand and gravel to carry out the experimental design.
【學(xué)位授予單位】：長沙理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TU473.1
【參考文獻(xiàn)】
相關(guān)期刊論文 前1條
1 馬曄,王陶;超長鉆孔樁自平衡法荷載試驗研究[J];巖土工程學(xué)報;2005年03期
，本文編號：2162924
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