樁端后注漿過程中漿土相互作用及其對樁基性狀影響研究
發(fā)布時間：2018-08-08 17:27
【摘要】：樁端后注漿技術(shù)已經(jīng)成為提高樁基承載力,控制樁基沉降的重要措施,已在工程實踐中得到了廣泛的應用。本文在分析土體可注入性的基礎(chǔ)上,對不同的漿土相互作用方式進行了分析,分別分析了漿液從可注入到部分可注入再到不可注入等過程中滲透、濾過、壓密和水泥漿壓濾等一系列問題,在此基礎(chǔ)上分析了后注漿對樁基性狀的影響。本文主要的工作和成果如下： (1)分析了土體的可注入性對漿液擴散及漿土相互作用的影響,研究了濾過效應對漿液滲透擴散的影響,在質(zhì)量守恒的基礎(chǔ)上引入線性濾過定律,建立了考慮濾過效應的漿液球形滲透擴散模型,得到了漿液濃度、土體孔隙率、漿液注入的水力梯度等隨注漿過程的變化情況。分析結(jié)果表明：由于濾過效應的影響,漿液在注入過程中,水泥顆粒逐漸濾出,土體的孔隙率逐漸減小,注漿水力梯度逐漸增加,離注漿孔越近,土體孔隙率降低越大,水泥顆粒的濾出量隨時間、濾過系數(shù)、注入速率、初始半徑的增加而增加,隨水灰比的增加而降低。注漿后通過樁端土層不同位置處動力觸探試驗發(fā)現(xiàn),離樁基越近,動力觸探擊數(shù)越大,土體的加固效果越好。 (2)考慮滲透注漿過程中注漿壓力逐漸轉(zhuǎn)化為滲透力的作用,分別分析了漿液球孔、柱孔擴散條件下滲透作用對土體的影響,得到了漿液滲透力作用下土體中的應力和變形情況,結(jié)果表明：球孔、柱孔條件下滲透產(chǎn)生的徑向應力隨水灰比和土體滲透系數(shù)的減小而增大,徑向變形隨土體模量增大而降低。分別給出了考慮滲流作用的球狀、柱狀壓密注漿模型,將注漿壓力分為直接作用在土體上轉(zhuǎn)換為有效應力的面力αp0和作為體力的滲流力(1-α)p0,分別考慮了兩部分對土體的作用,結(jié)果表明在離孔較近的主要加固區(qū)土體中的徑向應力和徑向位移隨著α值的減小而減小。利用傳統(tǒng)孔擴張壓密注漿理論得到結(jié)果偏不安全。 (3)在分析水泥漿液特性的基礎(chǔ)上,采用漿液泌水分界水灰比將漿液壓濾過程分為自由排水階段和非自由排水階段,在自由排水階段根據(jù)體積守恒得到漿液自由排水模型,在非自由排水階段借鑒固結(jié)排水理論,考慮漿土界面排水連續(xù)性,推導了漿液壓濾固結(jié)模型,通過對影響漿液非自由排水階段參數(shù)的分析表明,在非自由階段,漿體內(nèi)的超孔隙水壓力隨著時間不斷的消散,漿體脫水能力也逐漸降低,壓濾系數(shù)越大,漿土界面排水能力越好,漿體內(nèi)的超孔壓消散越迅速。進行了室內(nèi)單向壓濾試驗,對試驗結(jié)果進行反分析得到了不同注漿壓力和不同水灰比時壓濾系數(shù)的取值范圍。 (4)分析了樁端注漿預壓作用對樁基端阻力、側(cè)阻力的重要影響,考慮漿液上返對樁側(cè)阻力的加固作用,分析了漿液上返的條件,給出了考慮成層地層中漿液上返的計算方法,并通過工程實例說明了該方法的可行性；在分析不同注漿方式加固機理的基礎(chǔ)上,結(jié)合現(xiàn)有的樁側(cè)阻力、樁端阻力經(jīng)驗公式,分別給出了后注漿樁側(cè)阻力和端阻力的分析方法。并通過現(xiàn)場試驗對后注漿的加固作用進行了分析,結(jié)果表明漿液對砂性土的擠密效果較好；距離樁基越近,對土體的加密效果越好。 (5)給出了兩種計算后注漿樁沉降的方法,在荷載傳遞法的基礎(chǔ)上,采用雙曲線的荷載傳遞函數(shù),推導了后注漿樁樁身荷載沉降關(guān)系曲線；通過對后注漿樁承載力提高量的統(tǒng)計分析得出了在不同樁頂位移條件下承載力提高系數(shù)的分布情況,并通過正態(tài)分布函數(shù)進行了擬合,給出了一種基于沉降控制標準的后注漿承載力預測方法。最后通過工程實例證明了本文給出的兩種方法的合理性。
[Abstract]:Post grouting technology has become an important measure to improve the bearing capacity of pile foundation and control the settlement of pile foundation. It has been widely used in engineering practice. Based on the analysis of the injectivity of soil, this paper analyses the different methods of interaction between slurry and soil, and analyzes the inpouring of the slurry from injection to inpouring to non injection. A series of problems such as infiltration, filtration, compaction and cement slurry pressure filtration are used in the process of entry. On this basis, the effects of post grouting on the properties of pile foundation are analyzed. The main work and results of this paper are as follows:
(1) the influence of the injectivity of soil on the diffusion of slurry and the interaction of slurry and soil was analyzed. The effect of filtration effect on the infiltration and diffusion of the slurry was studied. The linear filtration law was introduced on the basis of the conservation of mass, and a spheric permeation diffusion model was established, which considered the filtration effect, and the slurry concentration, the porosity of soil and the injection of slurry were obtained. The analysis results show that the cement particles gradually filter out during the injection process, the porosity of the soil gradually decreases and the grouting hydraulic gradient increases gradually because of the influence of filtration effect. The hydraulic gradient of grouting gradually increases, the porosity of the soil decreases as the grouting Kong Yue is near, the filtration amount of the cement particle is with the time and filtration system. The number, injection rate and initial radius increase and decrease with the increase of water cement ratio. Through the dynamic penetration test at different positions of the pile end, the closer the pile foundation is, the greater the number of dynamic penetration is, the better the soil reinforcement effect is.
(2) considering the effect of grouting pressure gradually transformed into osmotic force in the process of infiltration grouting, the effect of infiltration on soil under the condition of slurry hole and column hole diffusion is analyzed, and the stress and deformation of soil under the effect of slurry permeability are obtained. The results show that the radial stress produced by the permeation under the condition of the hole and column hole is with the ratio of water to cement. With the decrease of soil permeability coefficient, the radial deformation decreases with the increase of soil modulus. The spherical and columnar compaction grouting model is given in consideration of the seepage effect, and the grouting pressure is divided into two parts, namely, the surface force alpha P0 converted to the effective stress in the soil and the physical force (1- alpha) P0, respectively. The results show that the radial stress and radial displacement of the soil in the main reinforcement area near the hole are reduced with the decrease of the value of the alpha.
(3) on the basis of the analysis of the characteristics of cement slurry, the slurry pressure filtration process is divided into free drainage stage and non free drainage stage by using the slurry flow boundary water cement ratio. In the free drainage stage, the free drainage model of the slurry is obtained according to the conservation of volume. The drainage continuity is considered by the consolidation and drainage theory in the non free drainage stage. The consolidation model of slurry pressure filtration is derived. Through the analysis of the parameters affecting the non free drainage phase of the slurry, it is shown that the excess pore water pressure in the slurry is gradually reduced with time in the non free stage, and the dehydration capacity of the slurry is gradually reduced. The greater the pressure filtration coefficient is, the better the water discharge capacity of the slurry interface is, the faster the excess pore pressure in the slurry is dissipated. The unidirectional pressure filtration test was carried out in laboratory, and the range of pressure filtration coefficient under different grouting pressure and water cement ratio was obtained by back analysis.
(4) the important effect of pile tip grouting on pile end resistance and side resistance is analyzed. The reinforcement effect of back resistance on the pile side is considered, the conditions of the return of the slurry are analyzed, the calculation method of the return of slurry in the stratified stratum is given, and the feasibility of the method is illustrated by an engineering example and the different grouting methods are analyzed. On the basis of the strengthening mechanism, combined with the existing pile side resistance and the empirical formula of pile end resistance, the analysis method of side resistance and end resistance of post grouting pile is given. The reinforcement effect of post grouting is analyzed by field test. The results show that the compaction effect of slurry to sand soil is better; the closer to the distance pile foundation, the encrypt to the soil The better the effect.
(5) two methods for calculating the settlement of post grouting piles are given. On the basis of load transfer method, the load transfer function of hyperbolic load is adopted to deduce the relationship curve of the load settlement of post grouting pile, and the distribution of the bearing capacity of the post grouting pile is obtained by the statistical analysis of the increase of the bearing capacity of the post grouting pile. By fitting the normal distribution function, a prediction method for the bearing capacity of the post grouting based on the settlement control standard is given. Finally, the rationality of the two methods presented in this paper is proved by an engineering example.
【學位授予單位】：浙江大學
【學位級別】：博士
【學位授予年份】：2013
【分類號】：TU473.1
本文編號：2172496
[Abstract]:Post grouting technology has become an important measure to improve the bearing capacity of pile foundation and control the settlement of pile foundation. It has been widely used in engineering practice. Based on the analysis of the injectivity of soil, this paper analyses the different methods of interaction between slurry and soil, and analyzes the inpouring of the slurry from injection to inpouring to non injection. A series of problems such as infiltration, filtration, compaction and cement slurry pressure filtration are used in the process of entry. On this basis, the effects of post grouting on the properties of pile foundation are analyzed. The main work and results of this paper are as follows:
(1) the influence of the injectivity of soil on the diffusion of slurry and the interaction of slurry and soil was analyzed. The effect of filtration effect on the infiltration and diffusion of the slurry was studied. The linear filtration law was introduced on the basis of the conservation of mass, and a spheric permeation diffusion model was established, which considered the filtration effect, and the slurry concentration, the porosity of soil and the injection of slurry were obtained. The analysis results show that the cement particles gradually filter out during the injection process, the porosity of the soil gradually decreases and the grouting hydraulic gradient increases gradually because of the influence of filtration effect. The hydraulic gradient of grouting gradually increases, the porosity of the soil decreases as the grouting Kong Yue is near, the filtration amount of the cement particle is with the time and filtration system. The number, injection rate and initial radius increase and decrease with the increase of water cement ratio. Through the dynamic penetration test at different positions of the pile end, the closer the pile foundation is, the greater the number of dynamic penetration is, the better the soil reinforcement effect is.
(2) considering the effect of grouting pressure gradually transformed into osmotic force in the process of infiltration grouting, the effect of infiltration on soil under the condition of slurry hole and column hole diffusion is analyzed, and the stress and deformation of soil under the effect of slurry permeability are obtained. The results show that the radial stress produced by the permeation under the condition of the hole and column hole is with the ratio of water to cement. With the decrease of soil permeability coefficient, the radial deformation decreases with the increase of soil modulus. The spherical and columnar compaction grouting model is given in consideration of the seepage effect, and the grouting pressure is divided into two parts, namely, the surface force alpha P0 converted to the effective stress in the soil and the physical force (1- alpha) P0, respectively. The results show that the radial stress and radial displacement of the soil in the main reinforcement area near the hole are reduced with the decrease of the value of the alpha.
(3) on the basis of the analysis of the characteristics of cement slurry, the slurry pressure filtration process is divided into free drainage stage and non free drainage stage by using the slurry flow boundary water cement ratio. In the free drainage stage, the free drainage model of the slurry is obtained according to the conservation of volume. The drainage continuity is considered by the consolidation and drainage theory in the non free drainage stage. The consolidation model of slurry pressure filtration is derived. Through the analysis of the parameters affecting the non free drainage phase of the slurry, it is shown that the excess pore water pressure in the slurry is gradually reduced with time in the non free stage, and the dehydration capacity of the slurry is gradually reduced. The greater the pressure filtration coefficient is, the better the water discharge capacity of the slurry interface is, the faster the excess pore pressure in the slurry is dissipated. The unidirectional pressure filtration test was carried out in laboratory, and the range of pressure filtration coefficient under different grouting pressure and water cement ratio was obtained by back analysis.
(4) the important effect of pile tip grouting on pile end resistance and side resistance is analyzed. The reinforcement effect of back resistance on the pile side is considered, the conditions of the return of the slurry are analyzed, the calculation method of the return of slurry in the stratified stratum is given, and the feasibility of the method is illustrated by an engineering example and the different grouting methods are analyzed. On the basis of the strengthening mechanism, combined with the existing pile side resistance and the empirical formula of pile end resistance, the analysis method of side resistance and end resistance of post grouting pile is given. The reinforcement effect of post grouting is analyzed by field test. The results show that the compaction effect of slurry to sand soil is better; the closer to the distance pile foundation, the encrypt to the soil The better the effect.
(5) two methods for calculating the settlement of post grouting piles are given. On the basis of load transfer method, the load transfer function of hyperbolic load is adopted to deduce the relationship curve of the load settlement of post grouting pile, and the distribution of the bearing capacity of the post grouting pile is obtained by the statistical analysis of the increase of the bearing capacity of the post grouting pile. By fitting the normal distribution function, a prediction method for the bearing capacity of the post grouting based on the settlement control standard is given. Finally, the rationality of the two methods presented in this paper is proved by an engineering example.
【學位授予單位】：浙江大學
【學位級別】：博士
【學位授予年份】：2013
【分類號】：TU473.1
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