逆断层错动引起上覆土层破裂的模型试验研究
发布时间：2018-10-19 15:17
【摘要】：我国活断层广泛分布,近年来快速城镇化使得城镇规模不断扩大,工业与民用建筑、地铁与输油管线等城市生命线工程不可避免地邻近或跨越断层。断层错动引起上覆土层破裂,对地表建筑物、地下管线和隧道等结构物造成巨大破坏,使人民生命财产安全受到严重威胁。本文采用常重力模型试验方法研究了逆断层错动作用下上覆砂土层的变形特征和破裂带扩展规律。主要研究工作包括： (1)研制了模拟断层错动引起上覆土层破裂过程的常重力模型试验装置。该装置可实现错动速率0～6mm/s、5个倾角(30/45/60/75/90°)的逆断层和正断层错动,模型土层厚度最大可达600mm。 (2)提出了采用PIV技术量测断层错动过程中上覆土体位移和应变的方法,实现了断层错动过程中地表隆起(沉陷)、上覆土层主剪切区变形及土体破裂过程的精确刻画。 (3)开展了9组逆断层错动模型试验,研究了逆断层错动作用下上覆砂土层破裂过程、地表隆起变形及土层剪切变形,对比分析了断层错动速率、土层厚度、土体密实度、场地倾斜对上覆土层变形特征和破裂带扩展规律的影响。试验结果表明： 1)逆断层错动过程中,上覆土层先后出现主、次2条破裂带。主破裂带起始扩展角与断层倾角一致,在向上发展过程中逐渐偏向下盘。当断层竖向位移达到土层厚度的5%左右时,主破裂带出露地表,此时扩展角β与土体内摩擦角Φ和地表倾角γ(以与断层倾角同向为正)满足β=45°-Φ/2+γ的关系。 2)逆断层错动作用下,上覆土层可划分成三个变形区,即下盘的“静态区”、上盘的“刚性区”和破裂带附近的“主剪切区”。主剪切区总体呈偏向上盘的倒三角形。随着错动位移量增加,主剪切区向上发展,主剪切区地表宽度非线性增长,且增长速率随错动位移量增加而减小。 3)地表隆起随着断层错动量增加而增大,最大地表坡度和坡度大于等于1/150的影响范围也逐渐增加,并最终趋于定值。当断层倾角为60°时,地表受影响范围约为土层厚度的1.0～1.3倍。 4)逆断层错动试验速率(0.05/0.16/0.50mm/s)和土层厚度(200/400/600mm)对上覆土层破裂规律的影响不明显；土体密实度越大,破裂带出露地表所需的竖向错动位移越小,主剪切区和地表受影响区越小,但地表最大坡度和破裂带水平传播距离越大。 5)场地地表倾角γ对土层剪切变形和破裂带扩展有重要影响。随着地表倾角增大,破裂带出露地表所需的竖向错动位移增大,破裂带水平传播距离减小。无论地表倾角γ由0°减小至-5°还是由0°增大至5°,均会导致地表陡坎最大坡角变大,地表受影响区域宽度变大。
[Abstract]:Active faults are widely distributed in China. In recent years rapid urbanization has made the scale of cities and towns expand constantly. Urban lifeline projects such as industrial and civil buildings subway and oil pipelines inevitably close to or cross faults. The fault dislocation causes the rupture of the overlying soil layer, which causes great damage to the structures such as surface buildings, underground pipelines and tunnels, which seriously threatens the safety of people's lives and property. In this paper, the deformation characteristics and fracture zone propagation of the overlying sand layer used in the reverse fault dislocation action are studied by using the method of constant gravity model test. The main research works are as follows: (1) A constant gravity model test device is developed to simulate the rupture process of overlying soil caused by fault dislocation. The device can realize the reverse fault and normal fault dislocation of 0 or 6 mm / s, 5 dip angles (30 / 45 / 60 / 75 / 90 掳), and the maximum thickness of the model soil layer can be up to 600mm. (2) the method of measuring the displacement and strain of the overlying soil in the process of fault dislocation by using PIV technique is put forward. The accurate description of surface uplift (subsidence), deformation of the main shear zone of overlying soil and the process of soil failure in the process of fault dislocation has been realized. (3) Nine sets of reverse fault dislocation model tests have been carried out. In this paper, the fracture process of overlying sand layer, surface uplift deformation and shear deformation of soil layer are studied. The fault dislocation rate, the thickness of soil layer and the compactness of soil are compared and analyzed. Effects of site tilt on deformation characteristics and fracture zone expansion of overlying soil. The experimental results show that: 1) in the process of reverse fault dislocation, there are two main and secondary rupture zones in the overlying soil layer. The initial spreading angle of the main fracture zone is consistent with the fault dip angle, and gradually deviates to the lower side during the upward development. When the vertical displacement of the fault reaches about 5% of the thickness of the soil layer, the main rupture zone is exposed to the surface. At this time, the extension angle 尾 and the internal friction angle 桅 of soil and the surface dip angle 纬 (positive to the dip angle of the fault) satisfy the relation of 尾 = 45 掳- 桅 / 2 纬. 2) the overlying soil can be divided into three deformation zones, that is, the "static zone" of the lower face. The "rigid zone" of the upper disc and the "main shear zone" near the rupture zone. In general, the main shear zone is an inverted triangle with a bias to the upper disc. With the increase of the dislocation displacement, the main shear zone develops upward, the surface width of the main shear zone increases nonlinear, and the growth rate decreases with the increase of the dislocation displacement. 3) the surface uplift increases with the increase of fault momentum. The influence range of the maximum surface slope and slope greater than or equal to 1 / 150 increases gradually and tends to a constant value. When the fault dip angle is 60 掳, the affected area of the surface is about 1.0 ~ 1.3 times of the thickness of the soil layer.) the effect of 0.05/0.16/0.50mm/s and 200/400/600mm on the rupture of the overlying soil layer is not obvious, and the density of the soil is larger. The smaller the vertical dislocation displacement required for the rupture zone out of the exposed surface, the smaller the main shear zone and the surface affected area. However, the maximum slope and horizontal propagation distance of the fracture zone are larger. 5) the slope 纬 of the site has an important effect on the shear deformation of soil layer and the propagation of fracture zone. With the increase of the surface inclination, the vertical displacement required for the rupture zone out of the surface increases, and the horizontal propagation distance of the fracture zone decreases. No matter the surface inclination 纬 decreases from 0 掳to -5 掳or increases from 0 掳to 5 掳, the maximum slope angle of the steep ridge becomes larger and the width of the affected area becomes larger.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU43
本文编号：2281524
[Abstract]:Active faults are widely distributed in China. In recent years rapid urbanization has made the scale of cities and towns expand constantly. Urban lifeline projects such as industrial and civil buildings subway and oil pipelines inevitably close to or cross faults. The fault dislocation causes the rupture of the overlying soil layer, which causes great damage to the structures such as surface buildings, underground pipelines and tunnels, which seriously threatens the safety of people's lives and property. In this paper, the deformation characteristics and fracture zone propagation of the overlying sand layer used in the reverse fault dislocation action are studied by using the method of constant gravity model test. The main research works are as follows: (1) A constant gravity model test device is developed to simulate the rupture process of overlying soil caused by fault dislocation. The device can realize the reverse fault and normal fault dislocation of 0 or 6 mm / s, 5 dip angles (30 / 45 / 60 / 75 / 90 掳), and the maximum thickness of the model soil layer can be up to 600mm. (2) the method of measuring the displacement and strain of the overlying soil in the process of fault dislocation by using PIV technique is put forward. The accurate description of surface uplift (subsidence), deformation of the main shear zone of overlying soil and the process of soil failure in the process of fault dislocation has been realized. (3) Nine sets of reverse fault dislocation model tests have been carried out. In this paper, the fracture process of overlying sand layer, surface uplift deformation and shear deformation of soil layer are studied. The fault dislocation rate, the thickness of soil layer and the compactness of soil are compared and analyzed. Effects of site tilt on deformation characteristics and fracture zone expansion of overlying soil. The experimental results show that: 1) in the process of reverse fault dislocation, there are two main and secondary rupture zones in the overlying soil layer. The initial spreading angle of the main fracture zone is consistent with the fault dip angle, and gradually deviates to the lower side during the upward development. When the vertical displacement of the fault reaches about 5% of the thickness of the soil layer, the main rupture zone is exposed to the surface. At this time, the extension angle 尾 and the internal friction angle 桅 of soil and the surface dip angle 纬 (positive to the dip angle of the fault) satisfy the relation of 尾 = 45 掳- 桅 / 2 纬. 2) the overlying soil can be divided into three deformation zones, that is, the "static zone" of the lower face. The "rigid zone" of the upper disc and the "main shear zone" near the rupture zone. In general, the main shear zone is an inverted triangle with a bias to the upper disc. With the increase of the dislocation displacement, the main shear zone develops upward, the surface width of the main shear zone increases nonlinear, and the growth rate decreases with the increase of the dislocation displacement. 3) the surface uplift increases with the increase of fault momentum. The influence range of the maximum surface slope and slope greater than or equal to 1 / 150 increases gradually and tends to a constant value. When the fault dip angle is 60 掳, the affected area of the surface is about 1.0 ~ 1.3 times of the thickness of the soil layer.) the effect of 0.05/0.16/0.50mm/s and 200/400/600mm on the rupture of the overlying soil layer is not obvious, and the density of the soil is larger. The smaller the vertical dislocation displacement required for the rupture zone out of the exposed surface, the smaller the main shear zone and the surface affected area. However, the maximum slope and horizontal propagation distance of the fracture zone are larger. 5) the slope 纬 of the site has an important effect on the shear deformation of soil layer and the propagation of fracture zone. With the increase of the surface inclination, the vertical displacement required for the rupture zone out of the surface increases, and the horizontal propagation distance of the fracture zone decreases. No matter the surface inclination 纬 decreases from 0 掳to -5 掳or increases from 0 掳to 5 掳, the maximum slope angle of the steep ridge becomes larger and the width of the affected area becomes larger.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU43
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，本文编号：2281524
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