交通荷载下盐渍化软土地基低路堤动力响应分析
发布时间：2018-12-05 14:18
【摘要】：本文依托工程为通古勒格淖尔至额尔克哈什哈公路,该项目位于腾格里沙漠,沙漠区域内,沙丘、盐沼、山地、湖盆、草滩及平原交错分布,路线穿过湖盆地带,较多分布为盐渍化软土。此外,沙漠地区公路多设计为低路堤,受交通荷载的影响更甚。本文通过现场调查与室内试验对公路沿线盐渍土分布特征进行了研究,得到了沿线盐渍土分区图;建立现场试验路,在施工期与运营期对路基进行沉降观测,结果表明,除去异常数据断面,采用风积沙、砂砾换填处治,沉降速率较小,沉降稳定,满足工程建设要求。根据本项目实际,采用简谐荷载模拟交通荷载,以分布带的方式实现荷载移动,建立了移动简谐荷载下三维路堤模型,对风积沙换填处治、车辆满载和车速40km/h下的路基动力响应进行了数值计算,分析了竖向位移、应力沿深度变化的规律以及动应力的滞后效应,得到了动力时程曲线,结合路基工作区概念,确定了该工况下风积沙路基动力响应影响深度约为1.9m。与上文同位置的地基换填深度对比,进一步验证了试验路段的处治方案是合理的。考虑超载、地基加固区材料及行车速度等因素,单因素变量控制进行数值计算。超载时,动力响应影响深度远大于满载下的1.9m,从竖向塑性应变区域可以看出,超载可能对路基及边坡造成很大的破坏;采用砂砾处治时,砂砾材料改善了上部路基的变形特性;动荷载的作用时间与幅值是动力响应的主要影响因素,竖向动位移、等效塑性应变值主要受作用时间的影响;车速增大引起了更大的动荷载幅值,导致竖向动应力的波动增长剧烈,竖向塑性应变越大。随着车速增大,动力响应愈加剧烈,随后变弱,对应车速下,动力响应有一个峰值,本文中108 km/h时,动力响应最为明显。与已有的试验研究成果进行了对比,结果表明,本文有限元模型数值计算结果在规律上是可靠的,得到的结论与试验段监测结果可以为其他类似地区盐渍化软土地基及低路堤设计施工作参考。
[Abstract]:The project is located in the Tenggri desert, desert area, sand dune, salt marsh, mountain, lake basin, grass beach and plain. The project is located in Tenggri desert, desert area, sand dune, salt marsh, mountain, lake basin, grass beach and plain. Most of them are salinized soft soil. In addition, the highway in desert area is mostly designed as low embankment, which is more affected by traffic load. In this paper, the distribution characteristics of salinized soil along the highway are studied through field investigation and indoor test, and the zoning map of saline soil along the highway is obtained. The site test road was set up and the subgrade settlement was observed during the construction period and the operation period. The results showed that apart from the abnormal data section, the sand and gravel were replaced by wind sand, the settlement rate was small, the settlement was stable, and the engineering construction requirement was satisfied. According to the actual situation of the project, the traffic load is simulated by harmonic load, and the load is moved by distributed belt. A three-dimensional embankment model under moving harmonic load is established, and the sand is replaced and filled. The dynamic response of roadbed under full load and speed 40km/h is numerically calculated. The law of vertical displacement, the variation of stress along depth and the hysteresis effect of dynamic stress are analyzed. The dynamic time history curve is obtained and combined with the concept of subgrade working area. The influence depth of dynamic response of wind-sand roadbed under this condition is about 1.9 m. Compared with the above-mentioned foundation replacement depth, it is further proved that the treatment scheme of the test section is reasonable. The single factor variable control is used to calculate the factors such as overload, material in the foundation reinforcement area and the driving speed. The influence depth of dynamic response under overload is much greater than that of 1.9 m under full load. It can be seen from the vertical plastic strain region that overload may cause great damage to roadbed and slope. When the gravel is treated with sand and gravel, the deformation characteristics of the upper roadbed are improved, the time and amplitude of the dynamic load are the main influencing factors of the dynamic response, the vertical dynamic displacement and the equivalent plastic strain value are mainly affected by the action time. The larger amplitude of dynamic load is caused by the increase of speed, and the fluctuation of vertical dynamic stress increases sharply. The larger the vertical plastic strain is, the larger the vertical plastic strain is. With the increase of the vehicle speed, the dynamic response becomes more intense and then weakens. The dynamic response has a peak value at the corresponding speed, and the dynamic response is the most obvious at 108 km/h in this paper. Compared with the existing experimental results, the results show that the numerical results of the finite element model in this paper are reliable in law. The conclusions obtained and the monitoring results of the test section can be used as reference for the design and construction of salinized soft soil foundation and low embankment in other similar areas.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U416.1
[Abstract]:The project is located in the Tenggri desert, desert area, sand dune, salt marsh, mountain, lake basin, grass beach and plain. The project is located in Tenggri desert, desert area, sand dune, salt marsh, mountain, lake basin, grass beach and plain. Most of them are salinized soft soil. In addition, the highway in desert area is mostly designed as low embankment, which is more affected by traffic load. In this paper, the distribution characteristics of salinized soil along the highway are studied through field investigation and indoor test, and the zoning map of saline soil along the highway is obtained. The site test road was set up and the subgrade settlement was observed during the construction period and the operation period. The results showed that apart from the abnormal data section, the sand and gravel were replaced by wind sand, the settlement rate was small, the settlement was stable, and the engineering construction requirement was satisfied. According to the actual situation of the project, the traffic load is simulated by harmonic load, and the load is moved by distributed belt. A three-dimensional embankment model under moving harmonic load is established, and the sand is replaced and filled. The dynamic response of roadbed under full load and speed 40km/h is numerically calculated. The law of vertical displacement, the variation of stress along depth and the hysteresis effect of dynamic stress are analyzed. The dynamic time history curve is obtained and combined with the concept of subgrade working area. The influence depth of dynamic response of wind-sand roadbed under this condition is about 1.9 m. Compared with the above-mentioned foundation replacement depth, it is further proved that the treatment scheme of the test section is reasonable. The single factor variable control is used to calculate the factors such as overload, material in the foundation reinforcement area and the driving speed. The influence depth of dynamic response under overload is much greater than that of 1.9 m under full load. It can be seen from the vertical plastic strain region that overload may cause great damage to roadbed and slope. When the gravel is treated with sand and gravel, the deformation characteristics of the upper roadbed are improved, the time and amplitude of the dynamic load are the main influencing factors of the dynamic response, the vertical dynamic displacement and the equivalent plastic strain value are mainly affected by the action time. The larger amplitude of dynamic load is caused by the increase of speed, and the fluctuation of vertical dynamic stress increases sharply. The larger the vertical plastic strain is, the larger the vertical plastic strain is. With the increase of the vehicle speed, the dynamic response becomes more intense and then weakens. The dynamic response has a peak value at the corresponding speed, and the dynamic response is the most obvious at 108 km/h in this paper. Compared with the existing experimental results, the results show that the numerical results of the finite element model in this paper are reliable in law. The conclusions obtained and the monitoring results of the test section can be used as reference for the design and construction of salinized soft soil foundation and low embankment in other similar areas.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U416.1
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