Theoretical Investigation, Numerical Simulation And Experimental Research Of Manhole Settlement Under Traffic Load

Manhole is an important accessory structure of municipal pipeline engineering. More and more municipal manholes appear in urban roads with the development of economic society and urbanization, many of which are located in urban main roads, secondary roads and branch roads. The common existence of severe settlement of urban road manholes under the traffic cyclic load seriously affects the driving safety and city appearance, and brings unnecessary loss to our country. Engineers, from the point of construction, have summarized that it is the poor quality of backfill which results in the quick and severe sinking of manholes just after road traffic opening.Firstly, drawing on the longitudinal vibration theory of pile, the longitudinal vibration equation of the manhole under traffic load in viscoelastic soil was established, The semi-analytical solution of manhole settlement in time-domain and the theoretical curve of manhole settlement were obtained with Laplace transform and inverse Fourier transform, the effect of manhole side soil parameters and manhole depth on manhole settlement was analyzed.Secondly, the two-dimensional plane strain model of manhole settlement under traffic load was established using the software of ANSYS, the effect of pavement, backfill, manhole material and reinforced concrete slab of manhole top on manhole settlement was analyzed. The indicator of backfill elastic modulus was proposed to make manhole settlement meet the requirement of specification.Finally, in considering both the economic cost and convenience of construction, two kinds of backfill materials and corresponding construction methods are recommended to conduct construction based on the laboratory tests.