土工格栅的主要性能及其工程应用

本文介绍了土工格栅的分类及其主要性能,并简要概述了土工格栅在工程中的应用,特别是在道路工程上的应用,对土工格栅今后的发展提出了展望。     

土工格栅加固在高速公路路基中的应用

分析了土工格栅的力学特点及其对路基的加固机理,结合工程经验总结了土工格栅的路基加固主要施工工艺及技术要点,并提出土工格栅加固过程中的施工质量控制措施。相关经验总结可为高速公路路基不均匀沉降的土工格栅加固提供参考。     

土工格栅加筋挡土墙主要结构型式及其破坏型式研究

阐述了土工格栅加筋挡土墙的加筋机理及其填筑的一般过程,简要介绍了土工格栅加筋挡土墙的主要结构型式,总结出了加筋挡土墙常见的破坏方式,并按照内部破坏型式与外部破坏型式两个类别对各种破坏型式进行了归纳和总结,为以后土工格栅加筋挡土墙的设计提供了依据和参考。     

浅谈土工格栅在公路工程中的应用

对塑料土工格栅、玻纤土工格栅和经编土工格栅的性能做了比较,对三种土工格栅的应用进行了总结,并对目前公路工程中的加筋选材问题提出了一些观点,以利于土工合成材料加筋技术在具体工程中的应用.     

土工格栅处理软土路基的有限元分析及应用研究

采用有限元软件PLAXIS,对土工格栅处理软土路基的变形特性及其影响因素进行了研究,分析表明,土工格栅对减小软基侧向位移、降低土体应力水平以及提高路基路堤安全系数有明显效果.通过在江苏某高速公路软土路段中的应用,并对路基侧向位移及沉降的实测研究,掌握了经土工格栅处理后,软土路基的基本变形规律.     

土工格栅在砂砾路基中的应用技术

介绍了西（安）户（县）高速公路土工格栅在砂砾路基中处理软基工的应用技术。并通过西户高速公路土工格栅的应用，从施工角度对土工格栅在砂砾路基中的施工技术进行分析和总结，进一步提出了土工格栅在砂砾路基施工铺设中采用毛砂找平层、保护层的施工工艺，对土格栅进行保护，防止土工格栅褶皱和损坏。     

对土工格栅在铁路工程中应用的几点认识

结合土工格栅在铁路工程中的应用情况,对铁路建设中常用的土工格栅作用机理、分类及特性进行了归纳总结,并对土工格栅在工程应用中存在的一些问题进行了分析,提出了一些改进建议,以供参考借鉴。     

土工格栅在路基不均匀沉降中的应用

土工格栅是近年来发展的一种新型土工合成材料，由于其性能优越而被广泛应用于市政公路、桥梁等工程领域。通过分析土工格栅的各种力学性能和土工格栅的加固原理，并结合工程实例对土工格栅布路基不均匀沉降处治中的应用进行了探讨。实践表明：土工格栅能有效解决路基的不均匀沉降问题。     

土工格栅受力状况的测试新技术

土工格栅在公路和铁路工程中应用广泛,但加筋结构中土工格栅效用的发挥仍不明晰。针对土工格栅受力状况测试的现状,提出采用电感式土工格栅位移计测量加筋结构中土工格栅应变的新技术,并在室内模型试验及现场土工格栅加筋路基试验段进行应用,通过电感式位移计测量的土工格栅应变与传统应变片测试结果及数值计算结果的对比,表明电感式土工格栅位移计测试技术准确可靠,适用于土工格栅加筋结构的现场测试。     

土工格栅在陡坡路堤施工中的应用

从土工格栅加筋土的性能和机理出发,详细介绍了土工格栅加筋土结构的设计要点及其施工工艺和流程,指出将土工格栅应用于陡坡路堤施工,有利于降低土地占用,提高工程效益。     

Interaction between geogrid reinforcement and tire chip–sand lightweight backfill

This paper deals with the interaction between the geogrid and the tire chip–sand mixture including the determination of the index properties of the backfill materials, the shear strength parameters, the interaction coefficients, and the efficiency of geogrid reinforcements in tire chip–sand backfills. Numerous experiments including index tests, compaction tests, pullout tests, and large-scale direct shear tests were conducted. Saint–Gobain (geogrid A) and Polyfelt (geogrid B) were selected as reinforcing materials. Tire chip–sand mixtures with mixing ratios of 0:100, 30:70, 40:60, and 50:50 by weight were used as fill materials. The test results revealed that the dry unit weight of tire chip–sand mixtures depended more on the sand content, and less on the water content. The mixture at the mixing ratio of 30:70 by weight or 50:50 by volume was found to be the most suitable fill material compared to other mixing ratios. The pullout resistance and the pullout interaction coefficients of geogrid A were slightly higher than those of geogrid B. In contrast, in the direct shear resistance, the direct shear interaction coefficients, and the efficiency values of geogrid B were slightly higher than those of geogrid A. Since geogrid B has the needed uniaxial reinforcement properties and its sufficient interaction characteristics with tire chip–sand mixture, the geogrid B was utilized in this study. The interaction coefficients between the tire chip–sand backfill with 30:70 mixing ratio by weight were found to be 0.71 in pullout mode and 0.92 in direct shear mode for geogrid B.     

土工格栅嵌锁力的理论计算方法探讨

针对土工格栅嵌锁力提出了一套简化的理论计算方法。通过对碎石填料和格栅作用模型的简化处理,给出了一种格栅与填料颗粒的单元嵌锁模式,并通过对该嵌锁模式下的填料颗粒的两种运动趋势—平移和转动进行讨论和分析,推导了不同条件下格栅的极限拉力,得出了最终的单元嵌锁力。     

Rate-Dependent Load-Strain Behaviour of Geogrid Arranged in Sand Under Plane Strain Compression

A number of previous experimental studies showed that polymer geogrid reinforcement as well as sand exhibit significantly rate-dependent behaviour. The viscous properties of polymer geogrids and Toyoura sand were independently evaluated by changing stepwise the strain rate as well as performing sustained loading and load/stress relaxation tests during otherwise monotonic loading in, respectively, tensile loading tests and drained plane strain compression (PSC) tests. The viscous properties of the two types of material were separately formulated in the same framework of non-linear three-component rheology model. The viscous response of geogrid-reinforced sand in PSC is significant, controlled by viscous properties of geogrid and sand. Local strain distributions in the reinforced sand specimen were evaluated by photogrametric analysis and used to determine the time history of the tensile strain in the geogrid. The time history of tensile load activated in the geogrid during sustained loading of reinforced sand specimen was deduced by analysing the measured time history of geogrid strain by the non-linear three-component model. It was found that the tensile load in the geogrid reinforcement arranged in a sand specimen subjected to fixed boundary loads could decrease with time. In that case, the possibility of creep rupture of geogrid is very low.     

地基处理中土工格栅加筋土体的机理研究

随着现代建筑事业对地基处理的要求日益增高,许多新的地基处理技术也得到开发和应用,其中土工格栅加筋土在土木工程中的应用也越来越广泛。该文首先阐述了土工格栅的种类和基本性能,然后从土体和土工格栅结合状态,以及力学性能方面,对其加筋机理进行了分析。研究表明:土工格栅可以依其良好的经济性能和加筋效果,应用于土木工程中。     

Large-scale tests of pile-supported earth platform with and without geogrid

In recent years, concrete piles, such as cast-in-place piles and precast concrete piles, have been increasingly used to support superstructures and embankments when they are constructed on soft soils. On the top of pile head elevation, a certain thick granular cushion including geosynthetic reinforcement is usually installed to transfer more external load onto the piles through soil arching effect and membrane effect. This technique involving the use of rigid piles, gravel cushion and geosynthetics is usually referred to as geosynthetic-reinforced and pile-supported earth platform. This paper presents two well-instrumented large-scale tests of pile-supported earth platform with and without geogrid reinforcement. The performance of the pile-supported platform with geogrid and its load transfer behavior were investigated and compared with those for the test without geogrid. The validation of the EBGEO (2010) calculation was performed based on the test results. The test results indicate that under lower applied load, the loads carried by the piles in the test with geogrid were close to those in the test without goegrid, while with an increase in external load the loads carried by piles in the test with geogrid increased faster than those in the test without geogrid. The negative skin friction for the test with geogrid was smaller than that for the test without geogrid. Based on the contours of earth pressures on foundation base the maximum earth pressures were distributed along the edge of central cap in the test with geogrid. The minimum earth pressures were on midway subsoil between two caps in both tests. Based on the test results, the efficacy for the test with geogrid was 2.5% greater than that for the test without geogrid at the end of loading. The efficacies predicted by the EBGEO (2010) calculation agreed well with the measured efficacies.     

土工格栅在路基路面工程中的应用

概述了土工格栅具有抗拉模量高、强度高、耐高温、耐腐蚀等优点,并对其进行了分类讨论,简单介绍了土工格栅在路基路面工程中的应用,有利于工程技术人员加深对该材料的了解,并更好的运用于实际工作中.     

Effectiveness of geogrid reinforcement in improvement of mechanical behavior of sand-contaminated ballast

Vertical stiffness and shear strength of ballasts are significantly degraded when contaminated with sands. There is a lack of solutions/studies related to strengthening ballast against sand contamination. Addressing this limitation, a comprehensive laboratory investigation was made on effectiveness of geogrid reinforcement for improvement of mechanical properties of sand-contaminated ballast. To this end, large-scale direct shear tests as well as plate load tests were conducted on geogrid-reinforced ballast samples prepared with different levels of sand contamination. The obtained results indicate that geogrid reinforcement considerably improves shear strength and vertical stiffness of contaminated ballast. A bandwidth was obtained for contamination levels in which ballast reinforcement is effective. Through examining geogrid with different aperture sizes and locations in the ballast layer, the best performance conditions of geogrid reinforcement were derived. The results were used to propose an effective method of ballast reinforcement and an efficient ballast maintenance approach in sandy areas.     

Effect of particle shape on the response of geogrid-reinforced systems: Insights from 3D discrete element analysis

Understanding soil-geogrid interaction is essential for the analysis and design of reinforced soil systems. Modeling this interaction requires proper consideration for the geogrid geometry and the particulate nature of the backfill soil. This is particularly true when angular soil particles (e.g. crushed limestone) are used as a backfill material. In this study, a three-dimensional (3D) discrete element model that is capable of capturing the response of unconfined and soil-confined geogrid material is developed and used to study the response of crushed limestone reinforced with geogrid and subjected to surface loading. The 3D shape of the crushed limestone is modeled by tracing the surface areas of a typical particle and fitting a number of bonded spheres into the generated surface. Model calibration is performed using triaxial tests to determine the microparameters that allow for the stress-strain behaviour of the backfill material to be replicated. To demonstrate the role of particle shape on the soil-geogrid interaction, the analysis is also performed using spherical particles and the calculated response is compared with that obtained using modeled surfaces. The biaxial geogrid used in this study is also modeled using the discrete element method and the unconfined response is compared with the available index test results. This study suggests that modeling the 3D geogrid geometry is important to accurately capture the geogrid response under both confined and unconfined conditions. Accounting for the particle shape in the analysis can significantly enhance the predicted response of the geogrid-soil system. The modeling approach proposed in this study can be adapted for other reinforced soil applications.     

Mechanical property and deformation behavior of geogrid reinforced calcareous sand

The strength and deformation properties of maritime geotechnical structures made primarily of calcareous sand are critical for project safety, and geogrid reinforcement is a promising new approach. A series of consolidated drained triaxial experiments were conducted to evaluate the mechanical property and deformation behaviors of geogrid reinforced calcareous sand (GRCS), taking into consideration the impacts of the geogrid layer, relative density, particle size, and confining pressure. In comparison to the unreinforced calcareous sand, the strength of the GRCS is greatly enhanced, and the deviatoric stress-strain curves are altered from slightly softening to hardening, as well as the suppressed shearing dilatancy. The geogrid, relative compactness, particle size, and confining pressure are all intimately related to the volume changes and shearing dilatancy of reinforced specimens, but particle crushing is mostly impacted by the confining pressure. The interactions of geogrid ribs and calcareous sand particles are summarized as two types of constraint and friction using scanning electron microscope tests to establish a simplified calculation method of horizontal and vertical equivalent additional stresses that could provide a reference for revealing the mechanical mechanism of GRCS.     

Experimental and numerical analysis of large scale pull out tests conducted on clays reinforced with geogrids encapsulated with coarse material

The pullout test is one of the methods commonly used to study pullout behavior of reinforcements. In the current research, large pullout tests (i.e. 100 × 60 × 60 cm) have been conducted to investigate the possibility of pullout resistance enhancement of clays reinforced with HDPE geogrid embedded in thin layers of sand. Pullout tests on clay–geogrid, sand–geogrid and clay–sand–geogrid samples have been conducted at normal pressures of 25, 50 and 100 kPa. Numerical modeling using finite element method has also been used to assess the adequacy of the box and geogrid sizes to minimize boundary and scale effects. Experimental results show that provision of thin sand layers around the reinforcement substantially enhances pullout resistance of clay soil under monotonic loading conditions and the effectiveness increases with increase in normal pressures. The improvement is more pronounced at higher normal pressures and an optimum sand layer thickness of 8 cm has been determined for maximum enhancement. Results of numerical analysis showed the adequacy of the box and geogrid length adopted as well as a relatively good agreement with experimental results.