均质土坡变形破坏过程及其变形破坏特征的大型离心机模拟研究
发布时间：2018-08-31 17:39
【摘要】：近年来,滑坡地质灾害频发,有必要建立其监测预警体系。而滑坡的变形破坏过程与变形破坏特征的研究对于监测预警该类滑坡具有重要意义。为了研究均质土坡的变形破坏过程与变形破坏特征,本次研究采用大型土工离心模型试验与数值模拟相结合的方式,先通过离心模型试验模拟特定尺寸条件的均质土坡,分析其变形破坏过程、变形破坏特征、变形破坏机理。在完成离心模型试验后,运用FLAC3D软件模拟不同尺寸条件(坡角、坡高的变化)下均质土坡的变形破坏规律,在一系列模拟的基础上对均质土坡的变形破坏过程、变形破坏特征、变形破坏机理进行分析总结。综合论文研究工作,得到以下几点结论:(1)在离心试验过程中,均质土坡的变形破坏过程可总括为:①局部变形破坏阶段;②变形破坏扩展阶段;③变形破坏发展贯通阶段。区别在于不同坡型条件的均质土坡局部变形开始的部位、变形的影响区域、变形的力学性质等的不同。具体的:当坡高较高、坡角较大(H40cm,α40°)时,坡体最先于后缘坡顶出现变形,在此出现的变形由拉性力造成。随着离心加速度的增大,坡顶受拉区域将出现拉裂缝,拉裂缝向Y方向和Z方向同时扩展,与此同时,前缘坡脚出现一定的应力集中现象。加速度进一步增大,变形破坏区域由坡顶沿坡面向坡脚处扩展,坡脚处出现少量剪切破坏。最终,拉裂区域与前缘剪切变形区域贯通;当坡高较低、坡角较小(H40cm,α40°)时,坡体最先于前缘坡脚处发生变形,变形主要由剪性力造成。随着离心加速度,剪切变形加大,拉动后面的土体变形,随着离心加速度的进一步增大,影响的变形区域逐渐增大至坡顶。整体上模型破坏的离心加速度值均在100~150g之间。(2)均质土坡的应力分布特征为:坡表应力值较大,易发生变形破坏;最小主应力的集中几乎都在坡体顶部;最大主应力的集中出现于坡体顶部或坡脚处;坡脚处出现应力集中的情况发生于大坡角或高坡高的坡型条件下。(3)均质土坡的变形破坏特征:前缘坡脚处发生较大的剪出变形(X方向),而在Y方向上几乎没有位移;在坡顶近坡面处,则主要发生Y方向上的位移,X方向发生相对较小由拉性力造成的位移;从坡顶到坡脚,X方向上的位移呈增加趋势,Y方向的位移呈减小趋势;随着坡高增大、坡角变陡,整体的位移量增大,受拉性力而产生的变形区域增大,坡顶可见沿Z方向发育的裂缝,坡脚出出现剪切破坏。坡体内出现剪应变增量带,成为潜在的滑动面(带)。(4)通过监测点的位移变化分析可知:坡表最先出现明显变形,当坡高较低、坡角较小时,变形主要发生在坡体浅表层;随着坡高、坡角的增大,坡表位移继续增大,坡体的变形的深度加大继续向坡体内扩展;随着坡高、坡角的进一步增大,坡体后缘的变形破坏深度加深,坡体内部分区域的变形发生较大调整。(5)通过对均质土坡的变形破坏机理分析,可归类为两类变形破坏模式:①“拉裂—蠕滑—剪断”型,主要发生在坡高较高、坡角较大的坡型中。该类型的变形破坏过程为先在后缘坡顶形成拉裂缝、而后在坡脚处发生蠕滑剪切作用、最后“剪断”中部土体,形成完整滑面,坡体完全失稳。由于坡顶裂缝向坡体内扩展较深,这类坡破坏时规模相对较大,属于中型滑坡,从力学机制上看类似于推移式滑坡。②“蠕滑—拉裂—剪切”型,主要发生在坡高较低、坡角较小的坡型中。即先在前缘坡脚处发生蠕滑剪切作用、而后带动或拉裂后面坡体、最后再发生剪切破坏,形成连续滑面,坡体整体失稳。
[Abstract]:In recent years, geological hazards of landslides occur frequently, so it is necessary to establish a monitoring and early warning system. The study of deformation and failure process and deformation and failure characteristics of landslides is of great significance for monitoring and early warning of such landslides. First, centrifugal model test is used to simulate the deformation and failure process, deformation and failure characteristics, and deformation and failure mechanism of homogeneous soil slope with specific size conditions. Based on a series of simulations, the deformation and failure process, deformation and failure characteristics, deformation and failure mechanism of homogeneous soil slope are analyzed and summarized. The difference lies in the position where the local deformation begins, the area affected by the deformation and the mechanical properties of the deformation of the homogeneous soil slope under different slope types. With the increase of centrifugal acceleration, tensile cracks will appear on the top of the slope, and the tensile cracks will expand in the direction of Y and Z at the same time. At the same time, there is a certain stress concentration phenomenon at the front foot of the slope. When the slope height is low and the slope angle is small (H40cm, alpha40 degrees), the deformation first occurs at the foot of the leading edge slope, which is mainly caused by shear force. (2) The stress distribution characteristics of homogeneous soil slopes are as follows: the surface stress value is large, and it is easy to occur deformation and failure; the minimum principal stress concentration is almost at the top of the slope; the maximum principal stress concentration occurs at the top or foot of the slope; and the stress concentration occurs at the foot of the slope. (3) Deformation and failure characteristics of homogeneous soil slopes: large shear deformation (X direction) occurs at the foot of the leading slope, but almost no displacement in the Y direction; displacement mainly occurs in the Y direction near the top of the slope, and displacement caused by tensile force relatively small in the X direction; From the top to the foot of the slope, the displacement in the X direction tends to increase, while the displacement in the Y direction tends to decrease; with the increase of the slope height, the slope angle becomes steeper, the overall displacement increases, and the deformation area caused by the tensile force increases. The cracks along the Z direction can be seen on the top of the slope, and the shear failure occurs at the foot of the slope. (4) Through the analysis of the displacement variation of monitoring points, it can be seen that the surface of the slope first appears obvious deformation, when the slope height is low and the slope angle is small, the deformation mainly occurs in the superficial layer of the slope; with the increase of the slope height and the slope angle, the displacement of the slope surface continues to increase, and the deformation depth of the slope body continues to expand to the slope body with the slope height and the slope angle further. (5) By analyzing the deformation and failure mechanism of homogeneous soil slope, it can be classified into two types of deformation and failure modes: (1) tensile-creep-shear type, which mainly occurs in the slope with higher slope height and larger slope angle. The process is to form tensile cracks at the top of the leading edge slope, then creep shear at the foot of the slope, and finally "shear" the middle soil, forming a complete sliding surface, and the slope is completely unstable. (2) Creep-slip-tension-shear type occurs mainly in the slope with low slope height and small slope angle, i.e. creep-slip shearing occurs at the foot of the leading slope, then drives or pulls the back slope, and finally shear failure occurs, resulting in continuous sliding surface and overall instability of the slope.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P642.22
本文编号：2215698
[Abstract]:In recent years, geological hazards of landslides occur frequently, so it is necessary to establish a monitoring and early warning system. The study of deformation and failure process and deformation and failure characteristics of landslides is of great significance for monitoring and early warning of such landslides. First, centrifugal model test is used to simulate the deformation and failure process, deformation and failure characteristics, and deformation and failure mechanism of homogeneous soil slope with specific size conditions. Based on a series of simulations, the deformation and failure process, deformation and failure characteristics, deformation and failure mechanism of homogeneous soil slope are analyzed and summarized. The difference lies in the position where the local deformation begins, the area affected by the deformation and the mechanical properties of the deformation of the homogeneous soil slope under different slope types. With the increase of centrifugal acceleration, tensile cracks will appear on the top of the slope, and the tensile cracks will expand in the direction of Y and Z at the same time. At the same time, there is a certain stress concentration phenomenon at the front foot of the slope. When the slope height is low and the slope angle is small (H40cm, alpha40 degrees), the deformation first occurs at the foot of the leading edge slope, which is mainly caused by shear force. (2) The stress distribution characteristics of homogeneous soil slopes are as follows: the surface stress value is large, and it is easy to occur deformation and failure; the minimum principal stress concentration is almost at the top of the slope; the maximum principal stress concentration occurs at the top or foot of the slope; and the stress concentration occurs at the foot of the slope. (3) Deformation and failure characteristics of homogeneous soil slopes: large shear deformation (X direction) occurs at the foot of the leading slope, but almost no displacement in the Y direction; displacement mainly occurs in the Y direction near the top of the slope, and displacement caused by tensile force relatively small in the X direction; From the top to the foot of the slope, the displacement in the X direction tends to increase, while the displacement in the Y direction tends to decrease; with the increase of the slope height, the slope angle becomes steeper, the overall displacement increases, and the deformation area caused by the tensile force increases. The cracks along the Z direction can be seen on the top of the slope, and the shear failure occurs at the foot of the slope. (4) Through the analysis of the displacement variation of monitoring points, it can be seen that the surface of the slope first appears obvious deformation, when the slope height is low and the slope angle is small, the deformation mainly occurs in the superficial layer of the slope; with the increase of the slope height and the slope angle, the displacement of the slope surface continues to increase, and the deformation depth of the slope body continues to expand to the slope body with the slope height and the slope angle further. (5) By analyzing the deformation and failure mechanism of homogeneous soil slope, it can be classified into two types of deformation and failure modes: (1) tensile-creep-shear type, which mainly occurs in the slope with higher slope height and larger slope angle. The process is to form tensile cracks at the top of the leading edge slope, then creep shear at the foot of the slope, and finally "shear" the middle soil, forming a complete sliding surface, and the slope is completely unstable. (2) Creep-slip-tension-shear type occurs mainly in the slope with low slope height and small slope angle, i.e. creep-slip shearing occurs at the foot of the leading slope, then drives or pulls the back slope, and finally shear failure occurs, resulting in continuous sliding surface and overall instability of the slope.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P642.22
【参考文献】
相关期刊论文 前4条
1 马迁 ,何英杰;光弹模型离心加载技术的新发展[J];长江科学院院报;1992年01期
2 黄润秋;裴向军;李天斌;;汶川地震触发大光包巨型滑坡基本特征及形成机理分析[J];工程地质学报;2008年06期
3 包承纲;我国离心模拟试验技术的现状和展望[J];岩土工程学报;1991年06期
4 张嘎;牟太平;张建民;;基于图像分析的土坡离心模型试验变形场测量[J];岩土工程学报;2007年01期
相关硕士学位论文 前1条
1 俞刚;基于FLAC~(3D)的滑坡稳定性分析及抗滑桩支挡研究[D];重庆交通大学;2012年
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