考慮應(yīng)力主軸變化下各向異性砂土靜動(dòng)力特性試驗(yàn)研究
發(fā)布時(shí)間：2019-07-03 20:13
【摘要】：在路堤、邊坡等工程中,地基土單元在固結(jié)過(guò)程中不僅主應(yīng)力大小會(huì)發(fā)生改變,大主應(yīng)力軸方向也會(huì)發(fā)生偏轉(zhuǎn),這種涉及應(yīng)力主軸偏轉(zhuǎn)的各向異性“傾斜”固結(jié)一方面使得砂土顆粒重新排列,進(jìn)而產(chǎn)生應(yīng)力誘發(fā)各向異性,另一方面會(huì)導(dǎo)致土體形成不同的初始固結(jié)應(yīng)力狀態(tài),包括初始豎向偏應(yīng)力以及初始扭剪應(yīng)力。在這種復(fù)雜的初始固結(jié)應(yīng)力狀態(tài)條件下,當(dāng)土體進(jìn)一步承受波浪荷載、交通荷載等涉及主應(yīng)力軸旋轉(zhuǎn)的復(fù)雜應(yīng)力路徑時(shí),土體表現(xiàn)出來(lái)的變形和強(qiáng)度特性將變得更加復(fù)雜。因而,在實(shí)驗(yàn)室模擬土體的復(fù)雜初始固結(jié)應(yīng)力條件,并進(jìn)一步開(kāi)展涉及應(yīng)力主軸變化的復(fù)雜應(yīng)力路徑下靜動(dòng)力試驗(yàn)研究,對(duì)于建立涉及應(yīng)力主軸變化這種復(fù)雜應(yīng)力條件下各向異性固結(jié)土體的變形規(guī)律和本構(gòu)模型具有十分重要的試驗(yàn)指導(dǎo)意義。本文利用空心圓柱扭剪儀針對(duì)各向同性固結(jié)和各向異性“傾斜”固結(jié)飽和砂土進(jìn)行了一系列涉及應(yīng)力主軸變化的復(fù)雜應(yīng)力路徑下靜動(dòng)力排水試驗(yàn)研究。主要開(kāi)展了以下工作研究：(1)分別針對(duì)各向同性固結(jié)和各向異性“傾斜”固結(jié)飽和砂土試樣進(jìn)行了一系列排水靜力剪切試驗(yàn),對(duì)比分析了制樣過(guò)程形成的固有各向異性以及“傾斜”固結(jié)誘發(fā)的各向異性對(duì)土體應(yīng)力應(yīng)變關(guān)系、峰值剪切強(qiáng)度、割線模量、剪脹關(guān)系、非共軸等靜力特性的影響,并建立了“傾斜”固結(jié)條件下增量峰值應(yīng)力比和初始割線模量與固結(jié)主應(yīng)力方向角和剪切主應(yīng)力增量角度差值之間關(guān)系。(2)通過(guò)對(duì)不同固結(jié)條件和主應(yīng)力方向下剪切過(guò)程中體應(yīng)變發(fā)展的對(duì)比分析,得到了獨(dú)立于剪切主應(yīng)力方向和固結(jié)條件的統(tǒng)一相位轉(zhuǎn)換應(yīng)力比(q/p)phase；結(jié)合應(yīng)力應(yīng)變非共軸發(fā)展規(guī)律,研究了非共軸對(duì)剪脹關(guān)系的影響,并通過(guò)引入非共軸因子修正了非共軸度造成的剪脹曲線與Rowe直線型剪脹曲線的偏差。(3)針對(duì)各向同性固結(jié)條件下主應(yīng)力軸旋轉(zhuǎn)試驗(yàn),分析了應(yīng)力比對(duì)體應(yīng)變發(fā)展模式的影響,得到了與靜力剪切試驗(yàn)一致的相位轉(zhuǎn)換應(yīng)力比(q/p)phase,當(dāng)應(yīng)力比低于相位轉(zhuǎn)換應(yīng)力比時(shí),主應(yīng)力軸旋轉(zhuǎn)過(guò)程中體應(yīng)變表現(xiàn)為體縮變形,反之為體脹變形。另一方面,通過(guò)引入非共軸因子分析了主應(yīng)力軸旋轉(zhuǎn)過(guò)程中非共軸對(duì)剪脹關(guān)系的影響。(4)針對(duì)各向異性“傾斜”固結(jié)條件下主應(yīng)力軸連續(xù)旋轉(zhuǎn)試驗(yàn),分析了固結(jié)誘發(fā)各向異性對(duì)主應(yīng)力軸連續(xù)旋轉(zhuǎn)過(guò)程中應(yīng)變分量發(fā)展以及應(yīng)變流動(dòng)過(guò)程中表現(xiàn)出的應(yīng)變?cè)隽看笮“l(fā)展和非共軸演變規(guī)律的影響；發(fā)現(xiàn)了主應(yīng)力軸旋轉(zhuǎn)周期內(nèi)最大非共軸角度可以通過(guò)應(yīng)變?cè)隽糠逯祵?duì)應(yīng)的旋轉(zhuǎn)角度與試樣最薄弱方向(70。)之間的滯后角度進(jìn)行度量。研究了旋轉(zhuǎn)圈數(shù)對(duì)體應(yīng)變發(fā)展模式的影響,隨著旋轉(zhuǎn)圈數(shù)增加,試樣相對(duì)密實(shí)度不斷增大,砂土試樣從中密向密實(shí)狀態(tài)轉(zhuǎn)變,從而導(dǎo)致從第5圈開(kāi)始在局部旋轉(zhuǎn)范圍內(nèi)出現(xiàn)體脹變形,而且體脹范圍也隨著旋轉(zhuǎn)圈數(shù)增加而不斷擴(kuò)大。(5)針對(duì)低路堤下地基土單元涉及應(yīng)力主軸偏轉(zhuǎn)的各向異性“傾斜”固結(jié)條件下的動(dòng)力循環(huán)排水試驗(yàn),研究了“傾斜”固結(jié)過(guò)程中形成的不同初始固結(jié)應(yīng)力狀態(tài),包括初始豎向偏應(yīng)力qvo和初始扭剪應(yīng)τ0,對(duì)動(dòng)力循環(huán)過(guò)程中豎向永久變形的影響。試驗(yàn)結(jié)果表明,第一圈永久豎向應(yīng)變與初始豎向偏應(yīng)力大小呈線性增長(zhǎng)的關(guān)系,而與初始扭剪應(yīng)力基本無(wú)關(guān)；在qv075kPa,τ0OkPa條件下,初始豎向偏應(yīng)力和初始扭剪應(yīng)力都會(huì)加速前期豎向永久變形的累積,但當(dāng)qv0≤75kPa,永久豎向應(yīng)變平均增長(zhǎng)率基本保持恒定,幾乎不受初始豎向偏應(yīng)力的影響；在Barksdale提出的對(duì)數(shù)模型的基礎(chǔ)上,建立了考慮初始豎向偏應(yīng)力和初始扭剪應(yīng)力綜合影響的永久豎向累積修正模型。(6)“傾斜”固結(jié)中形成的不同初始固結(jié)應(yīng)力狀態(tài)對(duì)動(dòng)力循環(huán)過(guò)程中體應(yīng)變發(fā)展的影響表明,存在一個(gè)臨界初始豎向偏應(yīng)力qv0=75kPa,將循環(huán)加載過(guò)程中體應(yīng)變發(fā)展分為體脹和體縮兩種模式；初始扭剪應(yīng)力的存在會(huì)使得土體在動(dòng)力循環(huán)中產(chǎn)生體脹趨勢(shì),而且體脹量隨著初始扭剪應(yīng)力的增大而增大。綜合考慮初始豎向偏應(yīng)力和初始扭剪應(yīng)力作用時(shí),在(σz-σθ)-2σzθ建立了以K0固結(jié)點(diǎn)為起點(diǎn)與水平軸夾角為2(α△σc)CCL的臨界固結(jié)線CCL (Critical Consolidated Line),當(dāng)α△σc(α△σc)CCL時(shí)后續(xù)動(dòng)力循環(huán)過(guò)程中表現(xiàn)為體縮變形,反之為體脹變形。(7)針對(duì)K0固結(jié)飽和砂土進(jìn)行了一系列交通荷載“心臟型”動(dòng)力循環(huán)應(yīng)力路徑以及不考慮主應(yīng)力軸旋轉(zhuǎn)效應(yīng)的普通動(dòng)力循環(huán)應(yīng)力路徑試驗(yàn)的對(duì)比研究,揭示了交通荷載引起的主應(yīng)力軸旋轉(zhuǎn)會(huì)加速豎向變形的累積以及減弱豎向回彈模量,并且且隨著循環(huán)應(yīng)力比增大,主應(yīng)力軸旋轉(zhuǎn)對(duì)豎向變形特性影響更加明顯,最后Uzan回彈模量的基礎(chǔ)上通過(guò)引入扭剪循環(huán)應(yīng)力比CSRt,提出了能反映主應(yīng)力軸旋轉(zhuǎn)的豎向回彈模量修正公式。
[Abstract]:in that construction of the embankment, side slope and the like, the foundation soil unit not only changes the principal stress in the consolidation process, but also the direction of the large principal stress axis is deflected, The stress-induced anisotropy, on the other hand, can lead to the formation of different initial consolidation stress states, including initial vertical bias and initial torsional shear stress. In this complex initial consolidation stress state, when the soil body is further subjected to the complex stress path of wave load, traffic load and the like related to the rotation of the principal stress axis, the deformation and strength characteristics of the soil body will become more complex. Therefore, in the laboratory, the complex initial consolidation stress condition of the soil body is simulated, and the static dynamic test research is further carried out under the complex stress path which relates to the change of the stress principal axis, It is of great significance to establish the deformation law and the constitutive model of the anisotropic consolidation soil under the complex stress condition involving the change of the stress principal axis. In this paper, a series of static and dynamic water drainage tests are carried out for isotropic consolidation and anisotropic "tilt" consolidation saturated sand by a hollow cylindrical torsion shear. The following work is mainly carried out: (1) a series of drainage static shear tests are carried out for the isotropic consolidation and the anisotropic "tilt"-consolidated saturated sand sample, The influence of the intrinsic anisotropy of the sample preparation process and the anisotropy on the stress and strain of the soil, the peak shear strength, the secant modulus, the shear expansion relation, the non-coaxial and other static characteristics is compared and analyzed. The relationship between the increment peak stress ratio and the initial secant modulus and the angle of the consolidation principal stress direction and the increment angle of the shear principal stress is established. (2) The unified phase transition stress ratio (q/ p) phase independent of the direction of the shear principal stress and the consolidation condition is obtained by the contrast analysis of the body strain development in the shear process under the different consolidation conditions and the principal stress direction, and the stress-strain non-coaxial development law is combined, The influence of the non-coaxial factor on the shear expansion is studied, and the deviation of the shear expansion curve and the Rowe linear shear expansion curve caused by the non-coaxial factor is corrected by introducing the non-coaxial factor. (3) The influence of the stress ratio on the body strain development mode is analyzed for the stress axis rotation test under the condition of isotropic consolidation, and the phase transition stress ratio (q/ p) phase which is consistent with the static shear test is obtained, and when the stress ratio is lower than the phase conversion stress ratio, The body strain during the rotation of the principal stress axis shows the deformation of the body, and vice versa. On the other hand, by introducing the non-coaxial factor analysis, the influence of the non-coaxial alignment on the shear-expansion relationship during the rotation of the principal stress axis is analyzed. (4) According to the continuous rotation test of principal stress axis under the condition of anisotropic "tilt" consolidation, the influence of consolidation-induced anisotropy on the development of the strain component and the development of the strain increment and the non-coaxial evolution of the strain during the continuous rotation of the principal stress axis is analyzed. It is found that the maximum non-coaxial angle in the rotation period of the principal stress axis can correspond to the weakest direction (70) of the sample by the rotation angle corresponding to the peak value of the strain increment. ) The lag angle between them is measured. The influence of the number of turns on the development mode of the body strain is studied. With the increase of the number of turns, the relative compactness of the sample is increasing, and the sand sample is changed from the dense state to the dense state, resulting in the occurrence of the deformation of the body in the local rotation range from the fifth turn, And the expansion range of the body is also expanded with the increase of the number of turns of the rotation. (5) The initial consolidation stress state formed during the "tilt" consolidation is studied for the dynamic cyclic drainage test under the condition of the anisotropic "tilt" consolidation under the deflection of the stress principal axis for the foundation soil unit under the low embankment, including the initial vertical deflection stress qvo and the initial torsion shear stress q0, The effect of the vertical permanent deformation in the power cycle. The experimental results show that the relationship between the permanent vertical strain of the first ring and the initial vertical partial stress is linearly increased, and is not related to the initial torsional shear stress; at the condition of qv075kPa and 2000OkPa, the initial vertical deflection stress and the initial torsional shear stress can accelerate the accumulation of the vertical permanent deformation in the early stage, However, when qv0 to 75kPa, the average growth rate of the permanent vertical strain is basically kept constant and is almost not affected by the initial vertical bias stress; on the basis of the logarithmic model proposed by Barksdale, a permanent vertical cumulative correction model considering the comprehensive effects of initial vertical partial stress and initial torsional shear stress is established. (6) The influence of different initial consolidation stress state formed in the "tilt" consolidation on the body strain development during the dynamic cycle shows that there is a critical initial vertical partial stress, qv0 = 75kPa, and the body strain development in the cyclic loading process is divided into two modes: The presence of the initial torsional shear stress will cause the body to expand in the power cycle, and the volume of the body will increase with the increase of the initial torsional shear stress. The critical consolidation line CCL (Critical Consolidated Line) with a K0 consolidation point as the starting point and a horizontal axis included angle is set up at a K0 consolidation point when considering the initial vertical partial stress and the initial torsional shear stress. In that follow-up power cycle, the body-contraction deformation is shown in the process of follow-up power cycle, on the contrary, the body is expanded and deformed. (7) A series of traffic load "heart type" dynamic cyclic stress paths are carried out for the K0 consolidated saturated sand, and the comparison study of the normal dynamic cyclic stress path test which does not take into account the rotation effect of the principal stress axis is carried out, It is revealed that the rotation of principal stress axis caused by traffic load can accelerate the accumulation of vertical deformation and decrease the modulus of vertical resilience, and as the ratio of cyclic stress increases, the influence of principal stress axis rotation on the characteristic of vertical deformation is more obvious. On the basis of the last Uzan elastic modulus, the vertical resilience modulus correction formula that can reflect the rotation of the principal stress axis is put forward by introducing the torsional shear circulation stress ratio (CSRt).
【學(xué)位授予單位】：浙江大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2015
【分類號(hào)】：TU441
本文編號(hào)：2509634
[Abstract]:in that construction of the embankment, side slope and the like, the foundation soil unit not only changes the principal stress in the consolidation process, but also the direction of the large principal stress axis is deflected, The stress-induced anisotropy, on the other hand, can lead to the formation of different initial consolidation stress states, including initial vertical bias and initial torsional shear stress. In this complex initial consolidation stress state, when the soil body is further subjected to the complex stress path of wave load, traffic load and the like related to the rotation of the principal stress axis, the deformation and strength characteristics of the soil body will become more complex. Therefore, in the laboratory, the complex initial consolidation stress condition of the soil body is simulated, and the static dynamic test research is further carried out under the complex stress path which relates to the change of the stress principal axis, It is of great significance to establish the deformation law and the constitutive model of the anisotropic consolidation soil under the complex stress condition involving the change of the stress principal axis. In this paper, a series of static and dynamic water drainage tests are carried out for isotropic consolidation and anisotropic "tilt" consolidation saturated sand by a hollow cylindrical torsion shear. The following work is mainly carried out: (1) a series of drainage static shear tests are carried out for the isotropic consolidation and the anisotropic "tilt"-consolidated saturated sand sample, The influence of the intrinsic anisotropy of the sample preparation process and the anisotropy on the stress and strain of the soil, the peak shear strength, the secant modulus, the shear expansion relation, the non-coaxial and other static characteristics is compared and analyzed. The relationship between the increment peak stress ratio and the initial secant modulus and the angle of the consolidation principal stress direction and the increment angle of the shear principal stress is established. (2) The unified phase transition stress ratio (q/ p) phase independent of the direction of the shear principal stress and the consolidation condition is obtained by the contrast analysis of the body strain development in the shear process under the different consolidation conditions and the principal stress direction, and the stress-strain non-coaxial development law is combined, The influence of the non-coaxial factor on the shear expansion is studied, and the deviation of the shear expansion curve and the Rowe linear shear expansion curve caused by the non-coaxial factor is corrected by introducing the non-coaxial factor. (3) The influence of the stress ratio on the body strain development mode is analyzed for the stress axis rotation test under the condition of isotropic consolidation, and the phase transition stress ratio (q/ p) phase which is consistent with the static shear test is obtained, and when the stress ratio is lower than the phase conversion stress ratio, The body strain during the rotation of the principal stress axis shows the deformation of the body, and vice versa. On the other hand, by introducing the non-coaxial factor analysis, the influence of the non-coaxial alignment on the shear-expansion relationship during the rotation of the principal stress axis is analyzed. (4) According to the continuous rotation test of principal stress axis under the condition of anisotropic "tilt" consolidation, the influence of consolidation-induced anisotropy on the development of the strain component and the development of the strain increment and the non-coaxial evolution of the strain during the continuous rotation of the principal stress axis is analyzed. It is found that the maximum non-coaxial angle in the rotation period of the principal stress axis can correspond to the weakest direction (70) of the sample by the rotation angle corresponding to the peak value of the strain increment. ) The lag angle between them is measured. The influence of the number of turns on the development mode of the body strain is studied. With the increase of the number of turns, the relative compactness of the sample is increasing, and the sand sample is changed from the dense state to the dense state, resulting in the occurrence of the deformation of the body in the local rotation range from the fifth turn, And the expansion range of the body is also expanded with the increase of the number of turns of the rotation. (5) The initial consolidation stress state formed during the "tilt" consolidation is studied for the dynamic cyclic drainage test under the condition of the anisotropic "tilt" consolidation under the deflection of the stress principal axis for the foundation soil unit under the low embankment, including the initial vertical deflection stress qvo and the initial torsion shear stress q0, The effect of the vertical permanent deformation in the power cycle. The experimental results show that the relationship between the permanent vertical strain of the first ring and the initial vertical partial stress is linearly increased, and is not related to the initial torsional shear stress; at the condition of qv075kPa and 2000OkPa, the initial vertical deflection stress and the initial torsional shear stress can accelerate the accumulation of the vertical permanent deformation in the early stage, However, when qv0 to 75kPa, the average growth rate of the permanent vertical strain is basically kept constant and is almost not affected by the initial vertical bias stress; on the basis of the logarithmic model proposed by Barksdale, a permanent vertical cumulative correction model considering the comprehensive effects of initial vertical partial stress and initial torsional shear stress is established. (6) The influence of different initial consolidation stress state formed in the "tilt" consolidation on the body strain development during the dynamic cycle shows that there is a critical initial vertical partial stress, qv0 = 75kPa, and the body strain development in the cyclic loading process is divided into two modes: The presence of the initial torsional shear stress will cause the body to expand in the power cycle, and the volume of the body will increase with the increase of the initial torsional shear stress. The critical consolidation line CCL (Critical Consolidated Line) with a K0 consolidation point as the starting point and a horizontal axis included angle is set up at a K0 consolidation point when considering the initial vertical partial stress and the initial torsional shear stress. In that follow-up power cycle, the body-contraction deformation is shown in the process of follow-up power cycle, on the contrary, the body is expanded and deformed. (7) A series of traffic load "heart type" dynamic cyclic stress paths are carried out for the K0 consolidated saturated sand, and the comparison study of the normal dynamic cyclic stress path test which does not take into account the rotation effect of the principal stress axis is carried out, It is revealed that the rotation of principal stress axis caused by traffic load can accelerate the accumulation of vertical deformation and decrease the modulus of vertical resilience, and as the ratio of cyclic stress increases, the influence of principal stress axis rotation on the characteristic of vertical deformation is more obvious. On the basis of the last Uzan elastic modulus, the vertical resilience modulus correction formula that can reflect the rotation of the principal stress axis is put forward by introducing the torsional shear circulation stress ratio (CSRt).
【學(xué)位授予單位】：浙江大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2015
【分類號(hào)】：TU441
【參考文獻(xiàn)】
相關(guān)期刊論文 前1條
1 范留明,李寧,丁衛(wèi)華;數(shù)字圖像偽彩色增強(qiáng)方法在巖土CT圖像分析中的應(yīng)用[J];巖石力學(xué)與工程學(xué)報(bào);2004年13期
，本文編號(hào)：2509634
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