铁路是国民经济的大动脉，更是关键基础设施和重大民生工程。路基作为铁道线路重要组成部分，其稳定性与耐久性直接关系到列车安全运行的平顺性和服役年限，尤其是高速铁路，对路基变形与轨道沉降都有严格技术要求。桩网复合路基结合了水平加筋垫层与桩基双向增强的优势，本文通过理论分析、室内模型试验与数值计算，研究煤矸石桩-土工格室复合路基的加固机理与承载特性。主要研究内容与结论如下：

(1) 分析桩土间土拱效应的产生机制，探讨煤矸石桩-土工格室复合结构加固路基的作用，土工格室具有网兜效应、筏板基础效应及拉膜效应等，桩体具有置换土体与侧向约束作用。在此基础上，研究加筋垫层-桩-土共同作用下的荷载传递过程，并分析其荷载分配与差异变形的协调关系，揭示桩网复合路基承载变形机理。

(2) 以煤矸石桩作为竖向加筋体、土工格室及格栅作为水平向加筋体，建立复合路基室内缩尺模型，进行静载试验，分析土工格室和格栅拉伸应力、桩体轴向应力以及桩顶与桩间土压力的变化规律。煤矸石桩-土工格室复合路基的沉降量相较于煤矸石桩-土工格栅复合路基沉降量降幅达29.71 %；土工格室拉应力较格栅整体增加了大约67.93 %，削弱桩土间的土拱效应；煤矸石桩中性点出现在约1/2桩长位置处。

(3) 通过有限单元法建立了三种工况下的复合路基数值模型，研究煤矸石桩复合路基中垫层处有无加筋体以及不同加筋体对承载特性的影响。静载作用下，将数值计算与室内模型试验结果进行对比分析，两者的荷载分布规律基本相似，结果验证了采用煤矸石桩-土工格室复合结构加固路基的有效性与合理性。三种工况下的复合结构加固路基效果依次为：煤矸石桩-土工格室/格栅复合路基优于煤矸石桩复合路基，煤矸石桩-土工格室复合路基优于煤矸石桩-土工格栅复合路基。

The railway is the main artery of the national economy, as well as the key infrastructure and a major livelihood project. As an important component of railway lines, the stability and durability of the subgrade are directly related to the smoothness and service life of safe train operation. Especially for high-speed railways, there are strict technical requirements for subgrade deformation and track settlement. The pile-net composite subgrade combines the advantages of bidirectional reinforcement of horizontal reinforced cushion and pile subgrade. Based on theoretical analysis, laboratory model test and numerical calculation, the strengthening mechanism and bearing characteristics of coal gangue pile-geocell composite subgrade were studied. The main research contents and conclusions are as follows：

(1)The mechanism of soil arching effect between pile and soil was analyzed, and the function of coal gangue pile-geocell composite structure in strengthening subgrade was discussed,  Geocell has net pocket effect, raft foundation effect, and tensile membrane effect. Pile has displacement soil and lateral constraint effect. On this basis, the load transfer process of reinforced cushion-pile-soil interaction was studied, the coordination relationship between load distribution and differential deformation was analyzed, and the bearing deformation mechanism of pile-net composite subgrade was revealed.

(2)Taking coal gangue piles as vertical reinforcement, geocells and grids as horizontal reinforcement, a scaled laboratory model of the composite subgrade was established and static load tests were conducted. The variation patterns of tensile stress, axial stress of pile body, and soil pressure between pile top and pile in the geocell and grid was analyzed. The settlement of the coal gangue pile geogrid composite subgrade has decreased by 29.71% compared to the coal gangue pile geogrid composite subgrade; The tensile stress of the geogrid increases by approximately 67.93% compared to the overall grid, weakening the soil arching effect between piles and soil; The neutral point of the coal gangue pile appears at approximately 1/2 of the pile length.

(3)The numerical models of composite subgrade under three working conditions was established by finite element method. The following two cases were studied: whether there is reinforcement at the cushion of the coal gangue pile composite subgrade, and the influence of different reinforcement on the bearing characteristics. Under static load, the numerical results are compared with the laboratory model test results. The load distribution patterns of the two are basically similar, and the results verify the effectiveness and rationality of using coal gangue pile geocell composite structure to reinforce the subgrade. The effect of composite structure reinforcement on subgrade under three working conditions is as follows: The coal gangue pile geogrid/grid composite subgrade is superior to the coal gangue pile composite subgrade, the coal gangue pile geogrid composite subgrade is superior to the coal gangue pile geogrid composite subgrade.

[1]黄奇帆. 伟大复兴的关键阶段-学习《中华人民共和国国民经济和社会发展第十四个五年规划和2035年远景目标纲要》的认识和体会[J]. 人民论坛, 2021, No.706(15): 6-10.

[2]《中华人民共和国国民经济和社会发展第十四个五年规划和2035年远景目标纲要》公布[J]. 都市快轨交通, 2021, 34(02): 122.

[3]2020年我国交通运输行业发展统计公报发布[J]. 隧道建设, 2021, 41(06): 963.

[4]胡一峰, 李怒放. 高速铁路无砟轨道路基设计原理[M]. 北京: 中国铁道出版社, 2010.

[5]刘钢, 罗强, 张良, 等. 基于累积变形演化状态控制的高速铁路基床结构设计计算方法[J]. 中国科学:技术科学, 2014, 44(07): 744-754.

[6]邹才能, 薛华庆, 熊波, 等. “碳中和”的内涵、创新与愿景[J]. 天然气工业, 2021, 1-12.

[7]Jia M. Research progress of comprehensive utilization of coal gangue [J]. Mineral Protection and utilization, 2019, 04: 46-52.

[8]谢和平, 任世华, 谢亚辰, 等. 碳中和目标下煤炭行业发展机遇[J]. 煤炭学报, 2021, 46(07): 2197-2211.

[9]宋晓波, 胡伯. 碳中和背景下煤炭行业低碳发展研究[J]. 中国煤炭, 2021, 47(07): 17-24.

[10]Jabonska B, Kityk A V, Busch M, et al. Thestructural and surface properties of natural and modifiedcoal gangue[J]. Journal of Environmental Management, 2017, 190: 80-90.

[11]Huang G D, Ji Y S, Li J, et al. Improving strength of calcinated coal gangue geopolymer mortars via increasing calcium content[J]. Construction and Building Materials, 2018, 166: 760-768.

[12]Shen L M. Composition of coal gangue and Study on its Reuse Technology [J]. Energy and Energy Conservation, 2020, 05:62-63.

[13]Verian K P, Ashraf W, Cao Y Z. Properties of recycled concrete aggregate and their influence in new concrete production[J]. Resources, Conservation and Recycling, 2018, 133: 30-49.

[14]陈景榜. 土工格室-水泥搅拌桩复合地基沉降特性试验研究[D]. 杭州: 浙江工业大学, 2020.

[15]赵明华, 张玲, 邹新军, 等. 土工格室-碎石桩双向增强复合地基研究进展[J]. 中国公路学报, 2009, 22(01): 1-10.

[16]Giroud J P, Noiray L. Geotextile-reinforced unpaved road design[J]. Journal of the Geotechnical Engineering Division, 1981, 107(9): 1233-1254.

[17]Giroud J P, Ah-Line C, Bonaparte R. Design of unpaved roads and trafficked areas with geogrids[M]. Polymer gird reinforcement. Thomas Telford Publishing, 1984: 116-127.

[18]Jones C, Lawson C R, Ayres D J. Geotextile reinforced piled embankments[J]. Geotextiles, Geomembranes and Related Products, Den Hoedt (ed.), 1990: 155-160.

[19]Schmertmann J H. A new, empirically based, arching theory and method for the design loading of a geogrid supporting overburden and spanning a void[J]. Schmertmann & Crapps, Inc., October, 1991.

[20]Hewlett W J, Randolph M F. Analysis of piled embankments[C]. International Journal of Rock Mechanics and Mining Sciences and Geomechanics Abstracts. Elsevier Science, 1988, 25(d): 297-298.

[21]Standard BS8006. Code of Practice for strengthened/reinforced soil and other fills[M]. British Standards Institute, 1995.

[22]赵明华, 陈艳平, 陈昌富, 等. 土工格室+碎石垫层结构体的稳定性分析[J]. 湖南大学学报(自然科学版), 2003(02): 68-72.

[23]赵明华, 陈炳初, 黄立葵. 土工格室低路堤-刚性路面结构体系模型试验[J]. 中国公路学报, 2011, 24(04): 1-6.

[24]赵明华, 刘猛, 龙军, 等. 双向增强复合地基土工格室加筋体变形分析[J]. 中国公路学报, 2014, 27(05): 97-104+124.

[25]赵明华, 郑玥, 刘猛, 等. 考虑纵横耦合变形的土工格室加筋体变形分析[J]. 湖南大学学报(自然科学版), 2019, 46(09): 89-99.

[26]顾良军, 杨晓华. 土工格室结构层拉伸性状试验研究[J]. 公路交通科技, 2007(01): 39-42.

[27]Sherin K S, Chandrakaran S, Sankar N. Effect of geocell geometry and multi-layer system on the performance of geocell reinforced sand under a square footing[J]. International Journal of Geosynthetics and Ground Engineering, 2017, 3(3): 1-11.

[28]Vibhoosha M. P., Bhasi Anjana, Nayak Sitaram. A review on the design, applications and numerical modeling of geocell reinforced soil[J]. Geotechnical and Geological Engineering, 2021, 39: 4035-4057.

[29]Barchard J M. Centrifuge modelling of piled embankments on soft soils[D]. Canada: University of New Brunswick, 1999.

[30]Chewh S H, Phoon H L. Geotextile reinforced piled embankment full scale model tests[C]. Proceeding of the 3rd Asian Regional Conference on Geosynthetics, Seoul, Korea June 21-23, 2004: 661-668.

[31]戴治恒, 张孟喜, 侯娟, 等. 高强格室和格栅格室加筋地基的试验对比[J]. 上海大学学报(自然科学版), 2019, 25(05): 796-806.

[32]陈景榜. 土工格室-水泥搅拌桩复合地基沉降特性试验研究[D]. 杭州: 浙江工业大学, 2020.

[33]汪海年, 张然, 周俊, 等. 土工格室加筋碎石基层变形机理的数值模拟[J]. 中南大学学报(自然科学版), 2015, 46(12): 4640-4646.

[34]曹文昭, 郑俊杰, 严勇. 桩承式变刚度加筋垫层复合地基数值模拟[J]. 岩土工程学报, 2017, 39(S2): 83-86.

[35]刘蓓蓓, 张孟喜, 王东. 基于强度折减法的土工格室加筋路堤稳定性分析[J]. 上海大学学报(自然科学版), 2018, 24(02): 287-295.

[36]陈成, 孙建, 芮瑞, 等. 基于有限元的土工格室加固有砟轨道沉降研究[J]. 铁道科学与工程学报, 2019, 16(10): 2427-2433.

[37]Luo X W, Lu Z, Yao H L, et al. Experimental study on soft rock subgrade reinforced with geocell[J]. Road Materials and Pavement Design, 2022, 23(9): 2190-2204.

[38]陈云敏, 贾宁, 陈仁朋. 桩承式路堤土拱效应分析[J]. 中国公路学报, 2004, 17(04): 4-9.

[39]陈仁朋, 贾宁, 陈云敏. 桩承式加筋路堤受力机理及沉降分析[J]. 岩石力学与工程学报, 2005(23): 4358-4367.

[40]刘吉福, 郑刚, 龚晓南. 附加应力法计算刚性桩复合地基路基沉降[J]. 岩土工程学报, 2018, 40(11): 1995-2002.

[41]陈盛原, 叶华洋, 张伟锋, 等. 路堤荷载作用下柔性桩复合地基的沉降分析[J]. 岩土力学, 2020, 41(09): 3077-3086.

[42]何腊平. 刚性桩复合地基沉降计算与模型试验研究[D]. 长沙: 湖南大学, 2009.

[43]薛新华, 魏永幸, 杨兴国, 等. CFG桩复合地基室内模型试验研究[J].中国铁道科学, 2012, 33(02): 7-12.

[44]闫澍旺, 郎瑞卿, 孙立强, 等. 基于薄板理论的刚性桩网复合地基桩土应力比计算[J]. 岩石力学与工程学报, 2017, 36(08): 2051-2060.

[45]杨涛, 陆振荣, 闫业强. 桩承式加筋路堤中土拱形态及荷载传递机理的数值分析[J]. 工业建筑, 2016, 46(08): 104-108.

[46]余闯, 刘松玉, 杜广印, 等. 桩承式路堤土拱效应的三维数值模拟[J]. 东南大学学报(自然科学版), 2009, 39(01): 58-62.

[47]周琛. CFG桩-网复合地基在山区高速公路中的优化设计与有限元分析[D]. 重庆: 重庆交通大学, 2011.

[48]Lai J X, Liu H Q, Qiu J L, et al. Settlement analysis of saturated tailings dam treated by cfg pile composite foundation[J]. Advances in Materials Science and Engineering, Volume, 2016: 7383762.

[49]Cheng X S, Gong L J, Liu G N. Bearing capacity characteristics and differential settlement of composite foundation with column-hammered and thrusted-expanded piles[J]. International Journal of Geomechanics, 2021, 21(9): 1943-5622.

[50]Yang C Z, Ni K, Wang S F. Analysis of the stress characteristics of cfg pile composite foundation under irregularity condition[J]. Civil Engineering Journal, 2017, 26(2).

[51]Radhika M. Patel, B. R. Jayalekshmi, R. Shivashankar. stress distribution in basal geogrid reinforced pile-supported embankments under seismic loads[J]. Transportation Infrastructure Geotechnology, 2021, 8(4): 516-541.

[52]俞建霖, 杨晓萌, 周佳锦,等. 桩-网复合地基支承路堤填土荷载传递规律[J]. 中南大学学报(自然科学版), 2022, 53(06): 2199-2210.

[53]Li S Y, Ye L M, Jiang H, et al. Analysis of load transfer law of short pile-net composite foundation for high-speed railway[J]. Shock and Vibration, 2022: 6120609.

[54]邓友生, 李令涛, 彭程谱等. 静动荷载下桩网结构路基模型试验研究[J]. 岩土力学, 2022, 43(08): 2149-2156.

[55]Wang X, Wang X Z, Yang G Q, et al. Field test on deformation characteristics of pile-supported reinforced embankment in soft soil foundation[J]. Sustainability, 2022, 14(13).

[56]马缤辉. 土工格室+碎石桩双向增强复合地基承载特性及沉降计算研究[D]. 长沙: 湖南大学, 2012.

[57]徐超, 宋世彤. 桩承式加筋路堤土拱效应的缩尺模型试验研究[J]. 岩石力学与工程学报, 2015, 34(S2): 4343-4350.

[58]徐超, 林潇, 沈盼盼. 桩承式加筋路堤张力膜效应模型试验研究[J]. 岩土力学, 2016, 37(07): 1825-1831.

[59]曹文昭. 桩承式加筋垫层技术作用机理研究[D]. 武汉：华中科技大学, 2016.

[60]Wang X, Wang X Z, Yang G Q, et al. Study on load transfer mechanism of pile-supported embankment based on response surface method[J]. Applied Sciences, 2022, 12(10): 4905.

[61]Dong J, Wu Z H, Li X, et al．Dynamic response and pile-soilinteraction of a heavy-haul railway embankment slope reinforced by micro-piles[J]. Computers and Geotechnics, 2018, 100: 144-157.

[62]Pham H V, Dias D, Dudchenko A. 3D modeling ofgeosynthetic-reinforced pile-supported embankment under cyclicloading[J]. Geosynthetics International, 2020, 27(2): 157-169．

[63]崔晓艳, 庄妍, 张希栋, 等. 循环荷载下桩承式路堤中土拱效应动力折减系数离散元研究[J].湖南大学学报(自然科学版), 2022, 49(09): 164-172.

[64]李永靖, 闫宣澎, 张旭, 等. 煤矸石集料钢筋混凝土柱的抗震性能试验研究[J]. 煤炭学报, 2013, 38(06): 1006-1011.

[65]李永靖, 邢洋, 张旭, 等. 煤矸石集料混凝土的耐久性试验研究[J]. 煤炭学报, 2013, 38(07): 1215-1219.

[66]董作超. 煤矸石集料混凝土的力学性能与抗碳化试验研究[D]. 北京: 中国矿业大学, 2016.

[67]张向东, 李庆文, 李桂秀, 等. 冻融-碳化耦合环境下自燃煤矸石混凝土耐久性试验研究[J]. 环境工程学报, 2016, 10(05): 2595-2600.

[68]严冰, 宋战平, 王艳, 等. 煤矸石混凝土抗冻性能试验研究[J]. 混凝土, 2017，No.329(03): 109-111+128.

[69]Zhang Y Z, Wang Q H, Zhou M, et al, Mechanical properties of concrete with coarse spontaneous combustion gangue aggregate (SCGA): experimental investigation and prediction methodology[J]. Construction and Building Materials, 2020, 255: 119337.

[70]白国良, 刘瀚卿, 刘辉, 等. 煤矸石理化特性及其对混凝土强度的影响[J]. 建筑结构学报: DOI: 10.14006/j.jzjgxb.2021.0573.

[71]白国良, 刘瀚卿, 朱可凡, 等. 陕北矿区不同矿源煤矸石混凝土抗压强度试验研究[J]. 土木工程学报: DOI: 10.15951/j.tmgcxb. 21121197.

[72]朱红光, 霍青杰, 倪亚东, 等. 煤矸石细集料-矿渣混凝土抗压强度与抗冻性能研究[J]. 材料导报, 2021, 35(22): 22085-22091.

[73]周梅, 李志国, 吴英强, 等. 石灰-粉煤灰-水泥稳定煤矸石混合料的研究[J]. 建筑材料学报, 2010, 13(02): 213-217.

[74]刘晓明, 唐彬文, 尹海峰, 等. 赤泥-煤矸石基公路路面基层材料的耐久与环境性能[J]. 工程科学学报, 2018, 40(04): 438-445.

[75]周梅, 张院强, 杨尚谕等. 自燃煤矸石砂轻混凝土单向叠合板的受弯性能[J]. 建筑材料学报, 2021, 24(05): 1066-1072.

[76]闫广宇, 周明凯, 陈潇, 等. 煤矸石集料路面基层材料应用研究[J]. 武汉理工大学学报(交通科学与工程版), 2021, 45(03): 568-573.

[77]李晓丹. 煤矸石型CFG桩复合地基材料试验研究[D]. 邯郸: 河北工程大学, 2011.

[78]詹鹏. 煤矸石型CFG模型桩的竖向极限承载力试验研究[D]. 延吉: 延边大学, 2015.

[79]方光秀, 詹鹏. 煤矸石型CFG桩承载性能与破坏形态试验研究[J]. 建筑技术, 2019, 50(02): 154-156.

[80]Liu H Q, Bai G L, Gu Yu,et al. The influence of coal gangue coarse aggregate on the mechanical properties of concrete columns[J]. Case Studies in Construction Materials, 2022, 17: e01315.

[81]Terzaghi, K. Theoretical soil mechanics[M]. New York: John Wiley & Sons, 1943, 182-215.

[82]谭可源. 刚性桩复合地基土拱效应的研究[C]. 中国公路学会, 第七届中国公路科技创新高层论坛. 北京: 人民交通出版社, 2015.

[83]郑玥. 基于弹性地基梁板理论的土工格室加筋体受力变形分析[D]. 长沙: 湖南大学, 2018.

[84]国家铁路局. 铁路路基设计规范: TB 10001-2016[S]. 北京: 中国铁道出版社, 2017.

[85]中华人民共和国水利部. 土工试验方法标准: GB/T 50123-2019, [S]. 北京: 中国计划出版社, 2021.

[86]中华人民共和国住房和城乡建设部. 建筑桩基技术规范: JGJ94-2008 [S]. 北京: 中国建筑工业出版社, 2008.