泡沫轻质土回填管道沟槽路面表层动力响应研究

Evaluating dynamic responses of pavement structures with pipeline trench backfilled with foamed lightweight soil

市政道路下伏管道沟槽常采用土、砂子、碎石等传统散体材料回填,由于沟槽空间受限,压实度难以满足设计要求,管道破损渗漏或交通荷载作用下,容易造成路面开裂,甚至塌陷。泡沫轻质土具有轻质、高强、自密实、抗渗漏等特性,可以将其应用于管道沟槽回填工程。为了研究泡沫轻质土回填管道沟槽的路面动力响应特性,以振动加速度和动位移为动力响应指标,开展泡沫轻质土回填段和中砂回填段的路面动力响应现场试验。试验车速分别为20,40和60 km/h,车重分别为空载、半载、满载,共9种试验工况。研究结果表明,泡沫轻质土回填区段测点振动加速度最大值、动位移最大值分别为31.93 mm/s^(2)、6.23μm,而中砂回填区段分别为35.79 mm/s^(2)、6.90μm。振动加速度峰值、动位移峰值均随车重、车速的增加而增大。车重由空载变为满载时,泡沫轻质土回填区段测点动位移峰值变化幅度仅为中砂回填区段测点的15.2%~51.0%;车速由20 km/h增加至60 km/h时,动位移峰值变化幅度为中砂回填区段测点的16.8%~66.8%。泡沫轻质土回填区段振动加速度峰值衰减率、动位移峰值衰减率分别为中砂回填区段的1.16~1.38倍及1.15~1.33倍,削减了沟槽回填区段路面测点振动的高频和低频成分,泡沫轻质土回填区段整体刚度较好,减振效果良好。研究成果可为泡沫轻质土回填管道沟槽的设计施工提供参考。

Traditional granular materials such as soil,sand,and gravel are often used to backfill the pipeline trenches under municipal roads.Due to the limited space of the trench,compaction degree is difficult to meet design requirements.It is thus susceptible to pavement cracking or collapse under traffic load or pipeline damage.Foamed lightweight soil(FLS)is adopted to backfill the pipeline trench for its advantages of light weight,compressive strength,self-compaction,and anti-leakage.The vibration acceleration and dynamic displacement were taken as dynamic response indices,and the field tests of the FLS backfilling test section and the medium sand backfilling test section were conducted to investigate the dynamic response characteristics,respectively.The vehicle loads of the field tests were divided into three types:no load,half load,and full load.Each loading stage was tested at three driving speeds:20 km/h,40 km/h,and 60 km/h,with a total of 9 testing schemes.The field tests results show that the maximum vibration acceleration and dynamic displacement of the FLS backfilling section are 31.93 mm/s^(2) and 6.23m,respectively,while those of the medium sand backfilling section are 35.79 mm/s^(2) and 6.90m,respectively.The peak vibration acceleration and peak dynamic displacement rise with increasing vehicle weight and speed.It is observed that the peak dynamic displacement range of measuring points in the FLS backfilling section only varies between 15.2%~51.0%of that in the medium sand backfilling section when the vehicle weight shifts from no load to full load.Similarly,when the vehicle speed increases from 20 km/h to 60 km/h,the range of peak dynamic displacement of measuring points in the FLS backfilling section is only 16.8%~66.8%of that in the medium sand backfilling section.The attenuation rates of peak vibration acceleration and peak dynamic displacement in the FLS backfilling section are 1.16~1.38 times and 1.15~1.33 times of that in the medium sand backfilling section,respectively.Backfilling with FLS reduces the high frequency and low frequency components of vibration.The FLS backfilling section has a consistent and sturdy overall stiffness and a good vibration reduction effect.The research findings have practical implications for the design and construction of the FLS backfilling pipeline trenches under municipal roads.