Research On The Trenchless Treatment Technology Of Bump At The Bridgehead Of Deep Soft Soil Foundation Operation Highway

Highways in the southeastern coastal areas of China are mostly built on deep soft soil foundations.Due to the lack of reasonable and effective control of soft foundations in early design or construction,and the increasing traffic after operation,a considerable proportion of expressways in the soft soil areas still have large settlement after being put into operation,which leads to the problem of bump at the bridgehead and brings great impact on traffic operation and maintenance.Aiming at the problem of bump at the bridgehead of deep soft foundations operation highway,various universities,scientific research institutes and design institutes have carried out relevant research and treatment,but the effect is not significant.At present,the traditional treatment measures need to occupy the road construction,which is difficult to match with the heavy traffic operation pressure faced by operating highways.This paper take a road bridge transition section in Wenzhou section of Ningbo Taizhou Wenzhou expressway as an example to study the trenchless treatment technology of the operation road bridgehead on deep soft soil foundation.Based on the results of previous geological exploration data collection and field investigation,the settlement theory calculation method and numerical simulation technology are fully used to predict the settlement of the bridgehead subgrade section.This paper puts forward the trenchless treatment technology for the operation road in the deep soft foundation area suitable for the project to evaluates the treatment effect,and studies the stability of the construction process In this paper,the following progress has been achieved through research:(1)This paper analyzed the current domestic and foreign scholars’ research and theory on the treatment of bump at the bridgehead,and summarized the application of trenchless treatment technology on the operating highway,which provide ideas and methods for the treatment technology research.(2)This paper systematically expounds the geological environment of the settlement section of a bridge head in Wenzhou section of Ningbo Taizhou Wenzhou expressway,and on this basis,analyzes the formation factors and current situation of the bump at the bridge head in the project,which lays a foundation for theoretical calculation and numerical simulation.(3)Through the field engineering geological investigation,this paper obtains the relevant field data and soil physical and mechanical parameters of the research object,selects a representative control section,and calculates the subsequent settlement of the untreated foundation using the stratified summation method(4)Using FLAC3D software,a three-dimensional numerical model of the foundation section of the bridgehead was established.On this basis,a fluid-structure coupling analysis was carried out to calculate the subsequent settlement and compare it with the theoretical calculation.It also provides a basis for evaluation and comparison of the treatment effect below(5)A comparative analysis of treatment techniques under different ideas,combined with the geological conditions and operational requirements of the bridgehead embankment section,put forward the technical solutions of "embankment lateral pilot hole replacement of light materials" and "lateral radiation grouting".Using FLAC3 D software simulate the effect of these two treatment measures on the settlement of the settlement under different parameters.On this basis,this paper proposes a combination scheme of dealing with the bump at the bridgehead of the highway operating on the deep soft soil foundation: The radiation grouting on both sides of the embankment strengthens the foundation soil to form a 8m thick artificial hard shell layer.In combination with the lateral plum piles of the embankment from top to bottom,the approach holes are arranged to replace the light materials with an aperture of 1m.After the treatment,the settlement control ratio of the combined treatment scheme reached 32.44%,which confirmed the effectiveness of the treatment scheme.The construction process is divided into different working conditions by simulating the construction of lateral approach hole of embankment.Through the simulation results,the construction stability is evaluated to determine the feasibility of treatment measures in the project.