岩质边坡锚杆—土工网垫喷播植草生态护坡植生层稳定性试验及数值模拟研究
发布时间：2018-08-30 09:09
【摘要】：近年来经济的迅猛发展促进了我国基础设施建设的飞速发展,但是工程建设中对岩土体的开挖、堆填将原有植被覆盖层破坏,直接导致岩质边坡产生大量次生裸地,破坏了工程所在地的生态环境,甚至造成山体滑坡及泥石流等严重次生灾害,危害公共安全。岩质边坡的植被恢复及生态防护技术逐步成为热点关注问题。现有的生态防护技术大多重点关注边坡的深层稳定性,边坡表面护坡植被大多凭借现场施工经验结合现场状况进行铺设,植被生长的植生基质层的稳定性缺乏系统的理论基础指导。本文针对锚杆-土工网垫喷播植生护坡技术这一新型复合型生态护坡技术,从工程角度出发,以生态护坡技术中的植生层土体为研究对象,采用现场试验,室内试验和数值模拟相结合的方法,对锚杆-土工网垫喷播植生护坡技术中植生层土体的稳定性开展研究,对该技术的应用及推广有重要的现实意义和工程价值。本文通过现场试验测定植生层土体的含水量及抗剪强度参数,作为数值模拟中的植生层土体结构单元的取值依据,分析植生层土体中含水量的变化规律和植生层土体沿坡向的位移及变形规律。论文的主要内容与结论如下:(1)选取岩质边坡坡度、三维土工网垫型号、植生密度三项因素开展现场试验,在护坡植被生长最旺盛时期测定带有植物根系的植生层土体的日常生长状态含水量及对应的抗剪强度指标;分析雨水在植生层土体中的入渗过程,并开展降雨模拟试验,测定植生层土体在饱和状态下的含水量及抗剪强度指标,测定降雨后相同时间间隔边坡表面不同位置和植生层土体不同深度的含水量,研究影响植生层土体含水量变化的各种因素。(2)选取岩质边坡坡度、三维土工网垫型号、植生密度、植生层厚度四项因素,应用FLAC3D有限差分软件建立模型。利用室内试验测得的不同含水量状态下植生层土体的抗剪强度参数作为数值模拟时植生层土体单元的取值依据,在大变形模式下分析植生层土体沿坡向位移及植生层土体变形规律。(3)护坡植被可延缓降雨时坡面径流的产生,保护坡面土体,固持水土;降雨后利于植生层土体表面水分的保持。土体中的土工网垫改变了植生层土体的渗透性能,对植生层土体的含水量变化起到抑制作用,有利于岩质边坡表面植生层的深层储水和自身稳定。(4)植生层土体沿坡向位移与植生密度负相关,与植生层厚度、植生层土体含水量、边坡坡度大小正相关。结合现场试验及数值模拟结果,边坡坡度为45°时,植生层厚度可铺设15cm;边坡坡度为60°时植生层厚度最大可铺设10cm;边坡坡度为70°时植生层厚度只能为5cm。
[Abstract]:In recent years, the rapid development of economy has promoted the rapid development of infrastructure construction in China, but the excavation of rock and soil mass in engineering construction, landfill will destroy the original vegetation cover, directly lead to a large number of secondary bare rock slope, destroy the ecological environment of the project site, and even cause landslides and debris flows and other serious secondary. Vegetation restoration and ecological protection techniques for rock slopes have gradually become a hot issue. Most of the existing ecological protection techniques focus on the deep stability of slopes. Most of the vegetation for slope protection relies on site construction experience and site conditions to lay, and the stability of vegetation growth in the vegetation substrate layer. In this paper, the anchor-geonet mat spraying seeding technology is a new composite ecological slope protection technology. From the engineering point of view, the planting layer soil in the ecological slope protection technology is taken as the research object, and the field test, indoor test and numerical simulation are combined to study the anchor-geonet mat. The study on the stability of soil in planting layer of spraying seeding technique for slope protection is of great practical significance and engineering value for its application and popularization. In this paper, the water content and shear strength parameters of soil in planting layer are measured by field test, which can be used as the basis for selecting the soil structure unit in numerical simulation, and the planting layer is analyzed. The main contents and conclusions of this paper are as follows: (1) Three factors, i.e. rock slope gradient, three-dimensional geonet cushion type and plant density, are selected to carry out field tests to determine the vegetation layer soil with plant roots during the peak growth period of slope protection vegetation. Water content in daily growing state and corresponding shear strength index; analyze infiltration process of rainwater in vegetation layer soil, carry out rainfall simulation test, measure water content and shear strength index of vegetation layer soil in saturated state, measure different position of slope surface and different depth of vegetation layer soil at the same time interval after rainfall (2) Four factors, including rock slope, three-dimensional geonet cushion type, planting density and planting layer thickness, were selected to establish the model by FLAC3D finite difference software. The shear strength parameters of planting layer soil under different water content were measured by laboratory tests. In the numerical simulation, the displacement along the slope and the deformation law of the soil in the vegetation layer are analyzed under the large deformation mode. (3) The slope protection vegetation can delay the generation of runoff on the slope, protect the soil on the slope and fix the soil and water; it is beneficial to the maintenance of the surface water of the soil in the vegetation layer after rainfall. The net cushion can change the permeability of the soil, restrain the change of the water content of the soil, and is beneficial to the deep water storage and self-stability of the vegetation layer on the surface of the rock slope. (4) The displacement of the soil along the slope is negatively correlated with the planting density, and is positively correlated with the thickness of the vegetation layer, the water content of the soil in the vegetation layer, and the slope gradient. According to the results of field test and numerical simulation, the thickness of vegetation layer can be laid 15 cm when slope gradient is 45 degrees, 10 cm when slope gradient is 60 degrees, and 5 cm when slope gradient is 70 degrees.
【学位授予单位】：青岛理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU457
本文编号：2212630
[Abstract]:In recent years, the rapid development of economy has promoted the rapid development of infrastructure construction in China, but the excavation of rock and soil mass in engineering construction, landfill will destroy the original vegetation cover, directly lead to a large number of secondary bare rock slope, destroy the ecological environment of the project site, and even cause landslides and debris flows and other serious secondary. Vegetation restoration and ecological protection techniques for rock slopes have gradually become a hot issue. Most of the existing ecological protection techniques focus on the deep stability of slopes. Most of the vegetation for slope protection relies on site construction experience and site conditions to lay, and the stability of vegetation growth in the vegetation substrate layer. In this paper, the anchor-geonet mat spraying seeding technology is a new composite ecological slope protection technology. From the engineering point of view, the planting layer soil in the ecological slope protection technology is taken as the research object, and the field test, indoor test and numerical simulation are combined to study the anchor-geonet mat. The study on the stability of soil in planting layer of spraying seeding technique for slope protection is of great practical significance and engineering value for its application and popularization. In this paper, the water content and shear strength parameters of soil in planting layer are measured by field test, which can be used as the basis for selecting the soil structure unit in numerical simulation, and the planting layer is analyzed. The main contents and conclusions of this paper are as follows: (1) Three factors, i.e. rock slope gradient, three-dimensional geonet cushion type and plant density, are selected to carry out field tests to determine the vegetation layer soil with plant roots during the peak growth period of slope protection vegetation. Water content in daily growing state and corresponding shear strength index; analyze infiltration process of rainwater in vegetation layer soil, carry out rainfall simulation test, measure water content and shear strength index of vegetation layer soil in saturated state, measure different position of slope surface and different depth of vegetation layer soil at the same time interval after rainfall (2) Four factors, including rock slope, three-dimensional geonet cushion type, planting density and planting layer thickness, were selected to establish the model by FLAC3D finite difference software. The shear strength parameters of planting layer soil under different water content were measured by laboratory tests. In the numerical simulation, the displacement along the slope and the deformation law of the soil in the vegetation layer are analyzed under the large deformation mode. (3) The slope protection vegetation can delay the generation of runoff on the slope, protect the soil on the slope and fix the soil and water; it is beneficial to the maintenance of the surface water of the soil in the vegetation layer after rainfall. The net cushion can change the permeability of the soil, restrain the change of the water content of the soil, and is beneficial to the deep water storage and self-stability of the vegetation layer on the surface of the rock slope. (4) The displacement of the soil along the slope is negatively correlated with the planting density, and is positively correlated with the thickness of the vegetation layer, the water content of the soil in the vegetation layer, and the slope gradient. According to the results of field test and numerical simulation, the thickness of vegetation layer can be laid 15 cm when slope gradient is 45 degrees, 10 cm when slope gradient is 60 degrees, and 5 cm when slope gradient is 70 degrees.
【学位授予单位】：青岛理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU457
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